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Sample records for fluidity determines sensitivity

  1. In Situ Determination of Clostridium Endospore Membrane Fluidity during Pressure-Assisted Thermal Processing in Combination with Nisin or Reutericyclin

    Science.gov (United States)

    Hofstetter, S.; Winter, R.; McMullen, L. M.

    2013-01-01

    This study determined the membrane fluidity of clostridial endospores during treatment with heat and pressure with nisin or reutericyclin. Heating (90°C) reduced laurdan (6-dodecanoyl-2-dimethylaminonaphthalene) general polarization, corresponding to membrane fluidization. Pressure (200 MPa) stabilized membrane order. Reutericyclin and nisin exhibit divergent effects on heat- and pressure-induced spore inactivation and membrane fluidity. PMID:23335780

  2. Determinants of HDL Cholesterol Efflux Capacity after Virgin Olive Oil Ingestion: Interrelationships With Fluidity of HDL Monolayer.

    Science.gov (United States)

    Fernández-Castillejo, Sara; Rubió, Laura; Hernáez, Álvaro; Catalán, Úrsula; Pedret, Anna; Valls, Rosa-M; Mosele, Juana I; Covas, Maria-Isabel; Remaley, Alan T; Castañer, Olga; Motilva, Maria-José; Solá, Rosa

    2017-09-08

    Cholesterol efflux capacity of HDL (CEC) is inversely associated with cardiovascular risk. HDL composition, fluidity, oxidation, and size are related with CEC. We aimed to assess which HDL parameters were CEC determinants after virgin olive oil (VOO) ingestion. Post-hoc analyses from the VOHF study, a crossover intervention with three types of VOO. We assessed the relationship of 3-week changes in HDL-related variables after intervention periods with independence of the type of VOO. After univariate analyses, mixed linear models were fitted with variables related with CEC and fluidity. Fluidity and Apolipoprotein (Apo)A-I content in HDL was directly associated, and HDL oxidative status inversely, with CEC. A reduction in free cholesterol, an increase in triglycerides in HDL, and a decrease in small HDL particle number or an increase in HDL mean size, were associated to HDL fluidity. HDL fluidity, ApoA-I concentration, and oxidative status are major determinants for CEC after VOO. The impact on CEC of changes in free cholesterol and triglycerides in HDL, and those of small HDL or HDL mean size, could be mechanistically linked through HDL fluidity. Our work points out novel therapeutic targets to improve HDL functionality in humans through nutritional or pharmacological interventions. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  3. Steric factors moderate conformational fluidity and contribute to the high proton sensitivity of Root effect hemoglobins.

    Science.gov (United States)

    Bonaventura, Celia; Henkens, Robert; Friedman, Joel; Siburt, Claire J Parker; Kraiter, Daniel; Crumbliss, Alvin L

    2011-10-01

    The structural basis of the extreme pH dependence of oxygen binding to Root effect Hbs is a long-standing puzzle in the field of protein chemistry. A previously unappreciated role of steric factors in the Root effect was revealed by a comparison of pH effects on oxygenation and oxidation processes in human Hb relative to Spot (Leiostomus xanthurus) and Carp (Cyprinodon carpio) Hbs. The Root effect confers five-fold increased pH sensitivity to oxygenation of Spot and Carp Hbs relative to Hb A(0) in the absence of anionic effectors, and even larger relative elevations of pH sensitivity of oxygenation in the presence of 0.2M phosphate. Remarkably, the Root effect was not evident in the oxidation of the Root effect Hbs. This finding rules out pH-dependent alterations in the thermodynamic properties of the heme iron, measured in the anaerobic oxidation reaction, as the basis of the Root effect. The alternative explanation supported by these results is that the elevated pH sensitivity of oxygenation of Root effect Hbs is attributable to globin-dependent steric effects that alter oxygen affinity by constraining conformational fluidity, but which have little influence on electron exchange via the heme edge. This elegant mode of allosteric control can regulate oxygen affinity within a given quaternary state, in addition to modifying the T-R equilibrium. Evolution of Hb sequences that result in proton-linked steric barriers to heme oxygenation could provide a general mechanism to account for the appearance of the Root effect in the structurally diverse Hbs of many species. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Determination of composition and fluidity of an alloy for impregnating hard alloys on the basis of titanium carbide

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    A. Z. Issagulov

    2016-07-01

    Full Text Available In this paper optimum compositions of a metal bond of Cr – Ni - Co system are determined by mathematical planning methods. As a response function, value of bending strength at a temperature of 800 °C was used. On the basis of the developed planning matrix samples of required composition were made, bending strength and long-term strength are measured. A certain composition of alloy-bond and its quantity is found. Spiral tests were conducted to determine fluidity.

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

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    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.

  6. D-myo-inositol derivatives alter liposomal membrane fluidity

    NARCIS (Netherlands)

    Brailoiu, E; Margineanu, A; Toma, CP; Filipeanu, CM; Rusu, [No Value; Branisteanu, DD

    We investigated the effect on membrane fluidity induced by D-myo-inositol derivatives (IP3, IP4, IP5, IP6). Fluidity was determined as the anisotropy of fluorescence polarisation fi om liposome model membranes labelled with DPH (1,6-diphenyl-1,3,5 hexatriene). IP3 (10(-10) to 10(-5) M) increased the

  7. D-myo-inositol derivatives alter liposomal membrane fluidity

    NARCIS (Netherlands)

    Brailoiu, E; Margineanu, A; Toma, CP; Filipeanu, CM; Rusu, [No Value; Branisteanu, DD

    1998-01-01

    We investigated the effect on membrane fluidity induced by D-myo-inositol derivatives (IP3, IP4, IP5, IP6). Fluidity was determined as the anisotropy of fluorescence polarisation fi om liposome model membranes labelled with DPH (1,6-diphenyl-1,3,5 hexatriene). IP3 (10(-10) to 10(-5) M) increased the

  8. 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.

  9. Improvement in blood fluidity by Kaempferia parviflora rhizome.

    Science.gov (United States)

    Murata, Kazuya; Deguchi, Takahiro; Fujita, Takanori; Matsuda, Hideaki

    2013-10-01

    Improvement in blood fluidity leads to the prevention of various lifestyle-related diseases. A raw material for improving blood fluidity has been long desired in the research area of functional and supplemental foods. We successfully showed an improvement in blood fluidity by the Zingiberaceae plant, Kaempferia parviflora. The rhizome of the plant reduced the blood passage time through a micro slit using a disseminated intravascular coagulation model. The mechanism was attributed to the activation of fibrinolysis, as demonstrated by elongation of the euglobulin lysis time and an in-vitro fibrinolysis assay. The active principles were determined to be methoxyflavones. The results show that the rhizome of K. parviflora is a promising candidate preventive agent for treating lifestyle-related diseases.

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

    KAUST Repository

    Noutsi, Pakiza

    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.

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

    Directory of Open Access Journals (Sweden)

    Pakiza Noutsi

    Full Text Available 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.

  12. Highly sensitive catalytic spectrophotometric determination of ruthenium

    Science.gov (United States)

    Naik, Radhey M.; Srivastava, Abhishek; Prasad, Surendra

    2008-01-01

    A new and highly sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III) has been established based on its catalytic effect on the oxidation of L-phenylalanine ( L-Pheala) by KMnO 4 in highly alkaline medium. The reaction has been followed spectrophotometrically by measuring the decrease in the absorbance at 526 nm. The proposed CKM is based on the fixed time procedure under optimum reaction conditions. It relies on the linear relationship where the change in the absorbance (Δ At) versus added Ru(III) amounts in the range of 0.101-2.526 ng ml -1 is plotted. Under the optimum conditions, the sensitivity of the proposed method, i.e. the limit of detection corresponding to 5 min is 0.08 ng ml -1, and decreases with increased time of analysis. The method is featured with good accuracy and reproducibility for ruthenium(III) determination. The ruthenium(III) has also been determined in presence of several interfering and non-interfering cations, anions and polyaminocarboxylates. No foreign ions interfered in the determination ruthenium(III) up to 20-fold higher concentration of foreign ions. In addition to standard solutions analysis, this method was successfully applied for the quantitative determination of ruthenium(III) in drinking water samples. The method is highly sensitive, selective and very stable. A review of recently published catalytic spectrophotometric methods for the determination of ruthenium(III) has also been presented for comparison.

  13. Effect of oxidative stress on plasma membrane fluidity of THP-1 induced macrophages.

    Science.gov (United States)

    de la Haba, Carlos; Palacio, José R; Martínez, Paz; Morros, Antoni

    2013-02-01

    Plasma membrane is one of the preferential targets of reactive oxygen species which cause lipid peroxidation. This process modifies membrane properties such as membrane fluidity, a very important physical feature known to modulate membrane protein localization and function. The aim of this study is to evaluate the effect of oxidative stress on plasma membrane fluidity regionalization of single living THP-1 macrophages. These cells were oxidized with H(2)O(2) at different concentrations, and plasma membrane fluidity was analyzed by two-photon microscopy in combination with the environment-sensitive probe Laurdan. Results show a significant H(2)O(2) concentration dependent increase in the frequency of rigid lipid regions, mainly attributable to lipid rafts, at the expense of the intermediate fluidity regions. A novel statistical analysis evaluated changes in size and number of lipid raft domains under oxidative stress conditions, as lipid rafts are platforms aiding cell signaling and are thought to have relevant roles in macrophage functions. It is shown that H(2)O(2) causes an increase in the number, but not the size, of raft domains. As macrophages are highly resistant to H(2)O(2), these new raft domains might be involved in cell survival pathways.

  14. Evidence that some membrane ligands modulate the plasmalemma fluidity of endothelial cells in culture.

    Science.gov (United States)

    Jinga, V V; Badea, M G; Hörer, O

    1986-01-01

    The effect of some membrane ligands on the plasmalemmal fluidity of endothelial cells from bovine aorta in culture was investigated. The ligands used were: cationic ferritin (pI 8.5), soybean agglutinin, concanavalin A, wheat germ agglutinin, as well as glutaraldehyde at different concentrations. The fluidity probe employed was 1,6-diphenyl-1, 3, 5-hexatriene (DPH) and the parameter determined to quantify the fluidity was fluorescence steady-state anisotropy. The optimum time interval required by the insertion of the fluorescent probe in plasmalemma and the appropriate density of cells in the sample were determined. Rigidisation of plasmalemma was detected following its interaction with glutaraldehyde at concentrations ranging from 0.5% to 2% (+8% to +14% relative to the controls). After exposing endothelial cells to wheat germ agglutinin, concanavalin A and cationic ferritin pI 8.5, no modifications in the steady-state DPH fluorescence anisotropy were noticed. However, plasmalemmal rigidisation of +10% to +14% relative to the controls was obtained when endothelial cells were treated with 1 mg/ml and 2 mg/ml of soybean agglutinin, respectively. The possible mechanism of membrane fluidity modulation by membrane ligands and the usefulness of such investigations are discussed.

  15. Explaination of nonlocal granular fluidity in terms of microscopic fluctuations

    Science.gov (United States)

    Zhang, Qiong; Kamrin, Ken

    A recently proposed granular constitutive law has shown capability to predict nonlocal granular rheology using a variable denoted ``granular fluidity''. This work is aimed at finding the microscopic physical meaning of fluidity in terms of fluctuations such as fluctuation of normalized shear stress and fluctuation of velocity. We try to predict the fluidity as a function of the fluctuation of normalized shear stress, and also test Eyring equation and kinetic theory based on the theoretical prediction proposed in other work. We find a consistent definition for the fluidity to be proportional to the product of the velocity fluctuations and some function of packing fraction divided by the average diameter of the grains. This definition shows predictive ability in multiple geometries for which flow behavior is nonlocal. It is notable that the fluidity is well-defined as a function of kinematic state variables, as one would hope for a quantity of this nature.

  16. Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes.

    Science.gov (United States)

    Santhosh, Poornima Budime; Drašler, Barbara; Drobne, Damjana; Kreft, Mateja Erdani; Kralj, Slavko; Makovec, Darko; Ulrih, Nataša Poklar

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) with multifunctional properties have shown great promise in theranostics. The aim of our work was to compare the effects of SPIONs on the fluidity and phase transition of the liposomal membranes prepared with zwitterionic phosphatidylcholine lipids. In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to bê11 nm), silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm). Small unilamellar vesicles prepared with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids and multilamellar vesicles prepared with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine lipids were encapsulated or incubated with the plain and surface-modified SPIONs to determine the fluidity and phase transition temperature of the bilayer lipids, respectively. Fluorescent anisotropy and differential scanning calorimetric measurements of the liposomes that were either encapsulated or incubated with the suspension of SPIONs did not show a significant difference in the lipid ordering and fluidity; though the encapsulated SPIONs showed a slightly increased effect on the fluidity of the model membranes in comparison with the incubated SPIONs. This indicates the low potential of the SPIONs to interact with the nontargeted cell membranes, which is a desirable factor for in vivo applications.

  17. Determination of soil organic phosphorus exchange sensitivity

    Science.gov (United States)

    Shand, Charles; Wendler, Renate; Lumsdon, David; Cooper, Pat; George, Timothy; Brown, Lawrie; Giles, Courtney; Stutter, Marc; Menezes-Blackburn, Daniel; Zhang, Hao; Wearing, Catherine; Haygarth, Philip; Blackwell, Martin; Darch, Tegan

    2015-04-01

    Soils contain both organic and inorganic phosphorus (P) species in varying proportions. Studies have shown that many soils contain substantial amounts of inositol hexaphosphate (IHP) and there is much interest worldwide in developing strategies to make some use of this recalcitrant resource for plant growth to reduce P fertilizer inputs. Little is known about the preference of ion exchange processes in the solubilisation of organic vs inorganic P forms in soils, an important first step in making P forms bioavailable. Although they do not possess biotic functions, resins provides a simple means to deplete P forms in soil allowing investigation of exchange selectivity between inorganic and organic P forms. The aim of our work was to determine new understanding of exchange selectivity in soils and provide insight into potential depletion and plant uptake of soil phosphorus, with emphasis on organic forms such as IHP. For our study we used a Cambisol sampled from an agricultural area (Tayport) near Dundee in Scotland. The soil had a high Olsen (0.5 M sodium bicarbonate at pH 8.5) extractable P status (84 mg P/kg) and P-31 nuclear magnetic resonance analysis of its NaOH/EDTA extract showed it contained a substantial proportion of IHP (21 % of total extractable P). For resin extraction we used anion exchange resin sheets (4.17 cm each side) in bicarbonate form to minimise pH related solubilisation effects. We used 3.5 g of soil in 75 ml of water and added 1, 2 or 3 resin squares. After equilibration the resin squares were removed and replaced with fresh resin squares a further 3 times. Phosphorus was recovered from the resin sheets by elution with 0.25 M sulphuric acid and analysed by inductively coupled plasma spectroscopy to determine total P, and colorimetrically with malachite green to determine inorganic P with the remainder assigned to organic P. The data showed that the resin preferentially removed inorganic P and even after four sequential extractions little or

  18. [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.

  19. 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.

  20. Detection of Membrane Fluidity in Submitochondrial Particles of Platelets and Erythrocyte Membranes from Mexican Patients with Alzheimer Disease by Intramolecular Excimer Formation of 1,3 Dipyrenylpropane

    Directory of Open Access Journals (Sweden)

    G.G. Ortiz

    2008-01-01

    Full Text Available It has been suggested that mitochondrial dysfunction and defects in membrane structure could be implied in AD pathogenesis. The aim of the present work was the study of membrane fluidity in submitochondrial platelet particles and erythrocyte membranes from Mexican patients. Blood samples were obtained from 30 patients with Alzheimer disease and 30 aged-matched control subjects. Membrane fluidity determinations were done using a very low concentration of the fluorescent dipyrenylpropane probe incorporated in both types of membranes. This probe is able to give excimer and monomer fluorescence, therefore it can be used to monitor fluidity changes in biological membranes.

  1. Influence of fine sediment on the fluidity of debris flows

    OpenAIRE

    HOTTA, Norifumi; Kaneko, Takahiro; Iwata, Tomoyuki; Nishimoto, Haruo

    2013-01-01

    Debris flows include a great diversity of grain sizes with inherent features such as inverse grading, particle size segregation, and liquefaction of fine sediment. The liquefaction of fine sediment affects the fluidity of debris flows, although the behavior and influence of fine sediment in debris flows have not been examined sufficiently. This study used flume tests to detect the effect of fine sediment on the fluidity of laboratory debris flows consisting of particles with various diameters...

  2. 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.

  3. Possible evolutionary origins of human female sexual fluidity.

    Science.gov (United States)

    Kanazawa, Satoshi

    2016-05-16

    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.

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

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    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.

  5. APOBEC3F determinants of HIV-1 Vif sensitivity.

    Science.gov (United States)

    Land, Allison M; Shaban, Nadine M; Evans, Leah; Hultquist, Judd F; Albin, John S; Harris, Reuben S

    2014-11-01

    HIV-1 Vif counteracts restrictive APOBEC3 proteins by targeting them for proteasomal degradation. To determine the regions mediating sensitivity to Vif, we compared human APOBEC3F, which is HIV-1 Vif sensitive, with rhesus APOBEC3F, which is HIV-1 Vif resistant. Rhesus-human APOBEC3F chimeras and amino acid substitution mutants were tested for sensitivity to HIV-1 Vif. This approach identified the α3 and α4 helices of human APOBEC3F as important determinants of the interaction with HIV-1 Vif.

  6. 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.

  7. Effect of Sodium Ferulate on Fluidity and Morphology of Cell Membrane in Ozone Induced Lung Injury

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective: To study the effect of sodium ferulate (SF), an active component of Radix Angelica, on lung damage induced by ozone (O3). Methods: Mice model of lung injury was induced by ozone inhalation and treated with SF. The level of lipid peroxide and microviscosity in alveolar epithelial cell membrane of the mice was determined, and the structural change of lung cells was observed by microscopy. Results: Ozone could increase the level of malondialdehyde (MDA) and the microviscosity in alveolar epithelial cell membrane, and induce inflammatory changes in morphologic structure. These abnormal changes were improved after SF administration, which was manifested as alleviation of heightened microviscosity, increase of membrane fluidity, as well as the basically normalized pulmonary cellular structure under microscope. Conclusion: SF has a preventive effect against oxidized pulmonary injury induced by ozone, the action of which could be through scavenging oxygen free radicals, reducing lipid peroxide production, increasing membranous fluidity and mitigating inflammatory changes in cell structure.

  8. Elucidating how bamboo salt interacts with supported lipid membranes: influence of alkalinity on membrane fluidity.

    Science.gov (United States)

    Jeong, Jong Hee; Choi, Jae-Hyeok; Kim, Min Chul; Park, Jae Hyeon; Herrin, Jason Scott; Kim, Seung Hyun; Lee, Haiwon; Cho, Nam-Joon

    2015-07-01

    Bamboo salt is a traditional medicine produced from sea salt. It is widely used in Oriental medicine and is an alkalizing agent with reported antiinflammatory, antimicrobial and chemotherapeutic properties. Notwithstanding, linking specific molecular mechanisms with these properties has been challenging to establish in biological systems. In part, this issue may be related to bamboo salt eliciting nonspecific effects on components found within these systems. Herein, we investigated the effects of bamboo salt solution on supported lipid bilayers as a model system to characterize the interaction between lipid membranes and bamboo salt. The atomic composition of unprocessed and processed bamboo salts was first analyzed by mass spectrometry, and we identified several elements that have not been previously reported in other bamboo salt preparations. The alkalinity of hydrated samples was also measured and determined to be between pH 10 and 11 for bamboo salts. The effect of processed bamboo salt solutions on the fluidic properties of a supported lipid bilayer on glass was next investigated by fluorescence recovery after photobleaching (FRAP) analysis. It was demonstrated that, with increasing ionic strength of the bamboo salt solution, the fluidity of a lipid bilayer increased. On the contrary, increasing the ionic strength of near-neutral buffer solutions with sodium chloride salt diminished fluidity. To reconcile these two observations, we identified that solution alkalinity is critical for the effects of bamboo salt on membrane fluidity, as confirmed using three additional commercial bamboo salt preparations. Extended-DLVO model calculations support that the effects of bamboo salt on lipid membranes are due to the alkalinity imparting a stronger hydration force. Collectively, the results of this work demonstrate that processing of bamboo salt strongly affects its atomic composition and that the alkalinity of bamboo salt solutions contributes to its effect on membrane

  9. Preliminary study on plasma membrane fluidity of Psychrophilic Yeast Rhodotorula sp. NJ298 in low temperature

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The ability of cell to modulate the fluidity of plasma membrane was crucial to the survival of microorganism at low temperature. Plasma membrane proteins, fatty acids and carotenoids profiles of Antarctic psychrophilc yeast Rhodotorula sp. NJ298 were investigated at -3 ℃, 0 ℃ and 8 ℃. The results showed that plasma membrane protein content was greater at -3 ℃ than that at 8 ℃, and a unique membrane polypeptide composition with an apparent molecular mass of 94.7 kDa was newly synthesized with SDS-PAGE analysis; GC analysis showed that the main changes of fatty acids were the percentage of unsaturated fatty acids (C18∶ 1 and C18∶ 2) and shorter chain saturated fatty acid (C10∶ 0) increased along with the decrease of the culture temperature from 8 ℃ to -3 ℃; HPLC analysis indicated that astaxanthin was the major functional carotenoids of the plasma membrane, percentage of which increased from 54.6±1.5% at 8 ℃ to 81.9±2.1% at -3 ℃. However the fluidity of plasma membrane which was determined by measuring fluorescence anisotropy was similar at -3 ℃, 0 ℃ and 8 ℃. Hence these changes in plasma membrane's characteristics were involved in the cellular cold-adaptation by which NJ298 could maintain normal plasma membrane fluidity at near-freezing temperature.

  10. Data Acquisition Protocol for Determining Embedded Sensitivity Functions.

    Science.gov (United States)

    Meyer, Janette J; Adams, Douglas E; Silvers, Janene

    2016-04-20

    The effectiveness of many structural health monitoring techniques depends on the placement of sensors and the location of input forces. Algorithms for determining optimal sensor and forcing locations typically require data, either simulated or measured, from the damaged structure. Embedded sensitivity functions provide an approach for determining the best available sensor location to detect damage with only data from the healthy structure. In this video and manuscript, the data acquisition procedure and best practices for determining the embedded sensitivity functions of a structure is presented. The frequency response functions used in the calculation of the embedded sensitivity functions are acquired using modal impact testing. Data is acquired and representative results are shown for a residential scale wind turbine blade. Strategies for evaluating the quality of the data being acquired are provided during the demonstration of the data acquisition process.

  11. Additional water use influencing strength and fluidity of recycled concrete

    Institute of Scientific and Technical Information of China (English)

    张学兵; 方志; 邓寿昌; 成珂; 覃银辉

    2008-01-01

    Through adding different additional water use,the compressive strength,splitting tensile strength and fluidity of recycled concrete of three aggregate combination forms were studied by experiment respectively.The experimental results show that with the increase of adding additional water use,the compressive strength and splitting tensile strength of recycled coarse aggregate concrete decrease,but that of recycled fine aggregate concrete and recycled all aggregate concrete increase firstly then decrease.When additional water use is added more 15% or 20% than that of basic ordinary concrete,the recycled coarse aggregate concrete and fine one can get pretty good fluidity.When it is added more 30%,the recycled all aggregate concrete has fluidity that is just satisfied.

  12. Determination of temperature of moving surface by sensitivity analysis

    CERN Document Server

    Farhanieh, B

    2002-01-01

    In this paper sensitivity analysis in inverse problem solutions is employed to estimate the temperature of a moving surface. Moving finite element method is used for spatial discretization. Time derivatives are approximated using Crank-Nicklson method. The accuracy of the solution is assessed by simulation method. The convergence domain is investigated for the determination of the temperature of a solid fuel.

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

    African Journals Online (AJOL)

    user

    process when used to produce turbine blades, impellers and impulse blades for ..... Figure 7 (a ) Mould design for fluidity test strip thickness 0.75mm metal .... mould and the casting to be estimated by the size of the air gap (assumed to be ...

  14. Epigallocatechin-3-gallate affects the growth of LNCaP cells via membrane fluidity and distribution of cellular zinc

    Institute of Scientific and Technical Information of China (English)

    Jun-guo YANG; Hai-ning YU; Shi-li SUN; Lan-cui ZHANG; Guo-qing HE; Undurti N. DAS; Hui RUAN; Sheng-rong SHEN

    2009-01-01

    Objective: To evaluate effects of epigallocatechin-3-gallate (EGCG) on the viability, membrane properties, and zinc distribution, with and without the presence of Zn2+, in human prostate carcinoma LNCaP cells. Methods: We examined changes in cellular morphology and membrane fluidity of LNCaP cells, distribution of cellular zinc, and the incorporated portion of EGCG after treatments with EGCG, Zn2+, and EGCG+Zn2+. Results: We observed an alteration in cellular morphology and a decrease in membrane fluidity of LNCaP cells after treatment with EGCG or Zn2+. The proportion of EGCG incorporated into liposomes treated with the mixture of EGCG and Zn2+ at the ratio of 1:l was 90.57%, which was significantly higher than that treated with EGCG alone (30.33%). Electron spin resonance (ESR) studies and determination of fatty acids showed that the effects of EGCG on the membrane fluidity of LNCaP were decreased by Zn2+. EGCG accelerated the accumulation of zinc in the mitochondria and cytosol as observed by atomic absorption spectrometer. Conclusion: These results show that EGCG interacted with cell membrane,decreased the membrane fluidity of LNCaP cells, and accelerated zinc accumulation in the mitochondria and cytosol, which could be the mechanism by which EGCG inhibits proliferation of LNCaP cells. In addition, high concentrations of Zn2+ could attenuate the actions elicited by EGCG.

  15. [Procedure for determination of individual sensitivity to antitumor drugs].

    Science.gov (United States)

    Abduvaliev, A A; Gil'dieva, M S; Tatarskiĭ, V P

    2006-05-01

    The present paper proposes to employ the cultured tumor cells of the breast and chick fibroblasts after long-term cultivation (for above 24 days) to determine their individual drug sensitivity and, as a criterion of cell damage, to use the percent of destruction of the cell layer formed in the wells 24 hours after drug insertion. It also presents the comparative results of tests of 2 cellular models that have been used to determine the in vitro sensitivity of the cells of breast cancer and chick fibroblasts to melfalan and its complex compound with copper acetylacetonate - MOK*M. At the same time, the cytotoxic activity of MOK*M and melfalan against tumor cells has been not shown to differ greatly (16.02+/-1.85 and 15.71+/-0.65% cell layer destruction, respectively), but the same activity of MOK*M against the model of intact cells (chick fibroblasts) was much less (15.23+/-1.97%) than that of melfalan (95.39+/-1.11%). The test system proposed by the authors is of certain informative value and it may be used for the determination of the individual sensitivity of tumor cells to antitumor drugs.

  16. The validity of an accelerometer-based method for estimating fluidity in the sit-to-walk task in a community setting.

    Science.gov (United States)

    Asakura, Tomoyuki; Miyazawa, Yoshiyuki; Usuda, Shigeru

    2017-01-01

    [Purpose] Fluidity in the sit-to-walk task has been quantitatively measured with three-dimensional motion analysis system. The purpose of this study was to determine the validity of an accelerometer-based method for estimating fluidity in community-dwelling elderly individuals. [Subjects and Methods] Seventeen community-dwelling elderly females performed a sit-to-walk task. The motion was recorded by an accelerometer, a three-dimensional motion analysis system and a foot pressure sensor simultaneously. The timings of events determined from the acceleration waveform were compared to the timings determined from the three-dimensional motion analysis data (task onset, maximum trunk inclination) or foot pressure sensor data (first heel strike). Regression analysis was used to estimate the fluidity index from the duration between events. [Results] The characteristics of the acceleration waveform were similar to those previously reported in younger adults. Comparisons of event timings from accelerometer and motion analysis system data indicated no systematic bias. Regression analysis showed that the duration from maximum trunk inclination to the first heel strike was the best predictor of fluidity index. [Conclusion] An accelerometer-based method using the duration between characteristic events may be used to precisely and conveniently assess fluidity in a sit-to-walk task in a community setting.

  17. The fluidity and molding ability of glass-forming Zr-based alloy melt

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The fluidity and filling ability of glass-forming Zr-based alloy melt in copper mould were investigated both theoretically and experimentally. The major factors which affected the flowing behavior of the metallic melt in the mold were determined,which provides the foundation for overcoming the contradiction between the filling and formation of amorphous alloy during the rapid cooling process of the metallic melts. The casting factors to prepare a metallic ring were discussed and selected. As a result,a Zr-based bulk metallic glass ring was prepared successfully.

  18. Sensitive Determination of Epinephrine Using Kinetic Spectrophotometric Method

    Directory of Open Access Journals (Sweden)

    Atefah Ekhtesasi

    2016-03-01

    Full Text Available In this study, thionine – bromate as a sensitive reaction system using kinetic spectrophotometric method for the determination of epinephrine is proposed. The method is based on the catalytic effect of epinephrine on the selected reaction system. The change in absorbance was followed spectrophotometrically as a criterion of the oxidation reaction progress. The effective reaction variables were optimized. Under optimized experimental conditions, calibration curve was linear over the range 0.4 – 12.8 mg/l and the detection limit was 0.13 mg/l for five replicate determinations of blank signal. The interfering effect of various species was also investigated. The developed procedure was successfully applied for the determination of diclofenac in pharmaceutical and biological samples satisfactorily.

  19. Physical determinants of radiation sensitivity in bacterial spores

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Shear rheology of lipid monolayers and insights on membrane fluidity

    Science.gov (United States)

    Espinosa, Gabriel; López-Montero, Iván; Monroy, Francisco; Langevin, Dominique

    2011-01-01

    The concept of membrane fluidity usually refers to a high molecular mobility inside the lipid bilayer which enables lateral diffusion of embedded proteins. Fluids have the ability to flow under an applied shear stress whereas solids resist shear deformations. Biological membranes require both properties for their function: high lateral fluidity and structural rigidity. Consequently, an adequate account must include, in addition to viscosity, the possibility for a nonzero shear modulus. This knowledge is still lacking as measurements of membrane shear properties have remained incomplete so far. In the present contribution we report a surface shear rheology study of different lipid monolayers that model distinct biologically relevant situations. The results evidence a large variety of mechanical behavior under lateral shear flow. PMID:21444777

  1. Fragmentation, fluidity, and transformation: nonlinear development in middle childhood.

    Science.gov (United States)

    Knight, Rona

    2011-01-01

    The results of a small group of children studied through ages six through eleven suggest that latency is no longer an accurate term to describe middle childhood and preadolescence. This longitudinal research suggests a more nonlinear process than has previously been documented in psychoanalytic research and supports a dynamic systems approach to development. Self structures break down and remain in an ongoing state of non-linear development. Without stable structural organization, sexual and aggressive thoughts and feelings are less contained and less differentiated throughout this period of development. Gender role identity is in a continuous state of fluidity during middle childhood. While both boys and girls experience gender role fluidity, the meaning of male and female gender identifications and the expression of sexual and aggressive feelings differ for boys and girls.

  2. 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.

  3. Association of resistin with impaired membrane fluidity of red blood cells in hypertensive and normotensive men: an electron paramagnetic resonance study.

    Science.gov (United States)

    Tsuda, Kazushi

    2016-10-01

    Abnormalities in physical properties of the cell membranes may strongly be linked to hypertension. Recent evidence indicates that resistin may actively participate in the pathophysiology of insulin resistance, diabetes mellitus, hypertension and other circulatory disorders. The present study was undertaken to investigate the possible relationships among plasma resistin, oxidative stress and membrane fluidity (a reciprocal value of membrane microviscosity) in hypertension. We measured the membrane fluidity of red blood cells (RBCs) in hypertensive and normotensive men using an electron paramagnetic resonance (EPR) and spin-labeling method. The order parameter (S) for the spin-label agents (5-nitroxide stearate) in EPR spectra of red blood cell (RBC) membranes was significantly higher in hypertensive men than in normotensive men, indicating that membrane fluidity was decreased in hypertension. Plasma resistin levels were correlated with systolic blood pressure and 8-iso-prostaglandin F2α levels (an index of oxidative stress). Furthermore, the order parameter (S) of RBCs significantly correlated with plasma resistin and plasma 8-isoPG F2α, suggesting that reduced membrane fluidity of RBCs might be associated with hyperresistinemia and increased oxidative stress. Multivariate regression analysis showed that, after adjustment for confounding factors, plasma resistin might be an independent determinant of membrane fluidity of RBCs. The EPR study suggests that resistin might have a close correlation with impaired rheologic behavior of RBCs and microcirculatory dysfunction in hypertension, at least in part, via an oxidative stress-dependent mechanism.

  4. Highly sensitive flow-injection chemiluminescence determination of pyrogallol compounds

    Science.gov (United States)

    Kanwal, Shamsa; Fu, Xiaohong; Su, Xingguang

    2009-12-01

    A highly sensitive flow-injection chemiluminescent method for the direct determination of pyrogallol compounds has been developed. Proposed method is based on the enhanced effect of pyrogallol compounds on the chemiluminescence signals of KMnO 4-H 2O 2 system in slightly alkaline medium. Three important pyrogallol compounds, pyrogallic acid, gallic acid and tannic acid, have been detected by this method, and the possible mechanism of the CL reaction is also discussed. The proposed method is simple, convenient, rapid (60 samples h -1), and sensitive, has a linear range of 8 × 10 -10 mol L -1 to 1 × 10 -5 mol L -1, for pyrogallic acid, with a detection limit of 6 × 10 -11 mol L -1, 4 × 10 -8 mol L -1 to 5 × 10 -3 mol L -1 for gallic acid with a detection limit of 9 × 10 -10 mol L -1, and 8 × 10 -8 mol L -1 to 5 × 10 -2 mol L -1 for tannic acid, with a detection limit of 2 × 10 -9 mol L -1, respectively. The relative standard deviation (RSD, n = 15) was 0.8, 1.1 and 1.3% for 5 × 10 -6 mol L -1 pyrogallic acid, gallic acid and tannic acid, respectively. The proposed method was successfully applied to the determination of pyrogallol compounds in tea and coffee samples.

  5. Determination of Vagal Baroreflex sensitivity in Normal Subjects

    Science.gov (United States)

    Wada, Naoki; Singer, Wolfgang; Gehrking, Tonette L.; Sletten, David M.; Schmelzer, James D.; Kihara, Mikihiro; Low, Phillip A.

    2014-01-01

    Introduction The Valsalva maneuver (VM) is used widely to quantify the sensitivity of the vagal baroreflex loop (vagal baroreflex sensitivity, BRS_v), but most studies have focused on the heart rate (HR) response to blood pressure (BP) decrement (BRS_v↓), even though the subsequent response to an increment in BP following the VM (BRS_v↑) is important and different. Methods We evaluated recordings of HR and BP in 187 normal subjects during the VM and determined both BRS_v↑ determined by relating HR to the BP increase following phase III and BRS_v↓. Results BRS_v↑ was related inversely to age. In addition, BRS_v↓, age, and magnitude of phase IV were independent predictors of BRS_v↑ in a multivariate model, accounting for 47% of the variance of BRS_v↑. Discussion The results indicate that both BRS_v↑ and BRS_v↓ become blunted with increasing age and that these indices relate to each other. PMID:24477673

  6. Salt sensitivity in chickpea is determined by sodium toxicity.

    Science.gov (United States)

    Khan, Hammad A; Siddique, Kadambot H M; Colmer, Timothy D

    2016-09-01

    Salt sensitivity in chickpea is determined by Na(+) toxicity, whereas relatively high leaf tissue concentrations of Cl(-) were tolerated, and the osmotic component of 60-mM NaCl was not detrimental. Chickpea (Cicer arietinum L.) is sensitive to salinity. This study dissected the responses of chickpea to osmotic and ionic components (Na(+) and/or Cl(-)) of salt stress. Two genotypes with contrasting salt tolerances were exposed to osmotic treatments (-0.16 and -0.29 MPa), Na(+)-salts, Cl(-)-salts, or NaCl at 0, 30, or 60 mM for 42 days and growth, tissue ion concentrations and leaf gas-exchange were assessed. The osmotic treatments and Cl(-)-salts did not affect growth, whereas Na(+)-salts and NaCl treatments equally impaired growth in either genotype. Shoot Na(+) and Cl(-) concentrations had markedly increased, whereas shoot K(+) had declined in the NaCl treatments, but both genotypes had similar shoot concentrations of each of these individual ions after 14 and 28 days of treatments. Genesis836 achieved higher net photosynthetic rate (64-84 % of control) compared with Rupali (35-56 % of control) at equivalent leaf Na(+) concentrations. We conclude that (1) salt sensitivity in chickpea is determined by Na(+) toxicity, and (2) the two contrasting genotypes appear to differ in 'tissue tolerance' of high Na(+). This study provides a basis for focus on Na(+) tolerance traits for future varietal improvement programs for salinity tolerance in chickpea.

  7. Financial Literacy of Youth. A Sensitivity Analysis of the Determinants

    Directory of Open Access Journals (Sweden)

    Nagar A. Κ.

    2008-04-01

    Full Text Available This paper reports on the potential use of Neural Network as a sensitivity modeling tool for the determinants of financial literacy. The financial literacy modeling in this research has been attempted to measure the literacy of youth in the Australian society with respect to their financial knowledge of Credit Cards, Loans and Superannuation (Pensions scheme in Australia that allows for choice of funds and investment decisions by the member. Based on the financial literacy related parameters, Neural Networks results showed good promise and capability for efficient financial literacy determinants, and represent a potentially robust and fault tolerant approach. The findings indicate that the determinants of credit card are significantly dependent on a student’s year of study, credit card status and daily routine, which has a strong relevance to respondents’ knowledge of credit cards. (n=1070; 9.0070 and 10.5898 respectively. This study did not have the intention to explore the skills of youth in order to measure the level of financial literacy but the objective was to test the basic financial knowledge of key products that is common to youth in Australian society. In so doing, the researchers were keen to identify the determinants of financial knowledge.

  8. 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

  9. Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes

    Directory of Open Access Journals (Sweden)

    Santhosh PB

    2015-09-01

    Full Text Available Poornima Budime Santhosh,1,* Barbara Drašler,2,* Damjana Drobne,2 Mateja Erdani Kreft,3 Slavko Kralj,4 Darko Makovec,4 Nataša Poklar Ulrih1,5 1Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, 2Department of Biology, Biotechnical Faculty, University of Ljubljana, 3Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, 4Department for Materials Synthesis, Jožef Stefan Institute, 5Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Ljubljana, Slovenia *These authors share equal first authorship Abstract: Superparamagnetic iron oxide nanoparticles (SPIONs with multifunctional properties have shown great promise in theranostics. The aim of our work was to compare the effects of SPIONs on the fluidity and phase transition of the liposomal membranes prepared with zwitterionic phosphatidylcholine lipids. In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to be ~11 nm, silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm. Small unilamellar vesicles prepared with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids and multilamellar vesicles prepared with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine lipids were encapsulated or incubated with the plain and surface-modified SPIONs to determine the fluidity and phase transition temperature of the bilayer lipids, respectively. Fluorescent anisotropy and differential scanning calorimetric measurements of the liposomes that were either encapsulated or incubated with the suspension of SPIONs did not show a significant difference in the lipid ordering and fluidity; though the encapsulated SPIONs showed a

  10. The fluidity of blood in African elephants (Loxodonta africana).

    Science.gov (United States)

    Windberger, U; Plasenzotti, R; Voracek, Th

    2005-01-01

    The large cellular volume of erythrocytes and the increased plasma concentration of proteins in elephants are factors which potentially affect blood rheology adversely. To verify blood rheology, routine hemorheologic variables were analyzed in four African elephants (Loxodonta africana), housed in the zoo of Vienna. Whole blood viscosity at three different shear rates (WBV at low shear rate: WBV 0.7 s(-1) and WBV 2.4 s(-1); WBV at high shear rate: WBV 94 s(-1) done by LS30, Contraves) and erythrocyte aggregation (aggregation indices AI by LS30; aggregation indices M0, M1 by Myrenne aggregometer) were high (WBV 94 s(-1): 5.368 (5.246/5.648); WBV 2.4 s(-1): 16.291 (15.605/17.629); WBV 0.7 s(-1): 28.28 (25.537/32.173) mPa s; AI 2.4 s(-1): 0.25 (0.23/0.30); AI 0.7 s(-1): 0.24 (0.23/0.28); M0: 7.8 (6.4/8.4); M1: 30.2 (25/31)). Plasma viscosity (PV) was increased as well (1.865 (1.857/1.912) mPa s) compared to other mammalian species. These parameters would indicate a decrease in blood fluidity in elephants. However, erythrocyte rigidity (LORCA, Mechatronics) was decreased, which in contrast, has a promotive effect on peripheral perfusion. Blood rheology of the elephants was determined by a high whole blood and plasma viscosity as the result of pronounced erythrocyte aggregation and high plasma protein concentration. Thus, in the terminal vessels the resistance to flow will be increased. The large erythrocytes, which might impede blood flow further due to geometrical reasons, however, had a pronounced flexibility. We conclude that the effect of the increased inner resistance to peripheral blood flow was counteracted by the decreased rigidity of the erythrocytes to enable an adequate blood flow in African elephants.

  11. Relationship Between Liquid Fluidity of Iron Ore and Generated Liquid Content During Sintering

    Science.gov (United States)

    Peng, Jun; Zhang, Lei; Liu, Li-xia; An, Sheng-li

    2017-02-01

    The fluidity of sintering liquid phase reflects the effective bonding range of the binder phase in the sintering process of iron ores. In this study, the liquid composition and quantity during sintering was calculated using FactSage 7.0 thermodynamic calculation software. The results show that two liquid phases are formed during sintering. One phase is generated at about 1373 K (1100 °C) and the other is generated at about 1523 K (1250 °C). The liquid fluidity index and the low-temperature liquid phase are closely related. The higher-temperature liquid phase has little influence on the liquid fluidity index. The larger the amount of low-temperature liquid phase generated, the higher the liquid fluidity index is. The alkalinity of the low-temperature liquid phase has insignificant influence on the liquid fluidity index. The content of SiO2 in the iron ore is the main factor that affects the liquid fluidity index during sintering. The liquid fluidity index increases greatly with increasing SiO2 content. In contrast, Al2O3 content has little influence on the liquid fluidity index, with an increase in the Al2O3 content only slightly increasing the liquid fluidity index. An increase in the MgO content of the iron ore can reduce liquid generation, promote the spinel generation, and decrease the liquid fluidity index during sintering.

  12. Genetic determinants of sensitivity to beryllium in mice.

    Science.gov (United States)

    Tarantino-Hutchison, Lauren M; Sorrentino, Claudio; Nadas, Arthur; Zhu, Yiwen; Rubin, Edward M; Tinkle, Sally S; Weston, Ainsley; Gordon, Terry

    2009-06-01

    Chronic beryllium disease (CBD), an irreversible, debilitating granulomatous lung disease is caused by exposure to beryllium. This occupational hazard occurs in primary production and machining of Be-metal, BeO, beryllium - containing alloys, and other beryllium products. CBD begins as an MHC Class II-restricted, T(H)1 hypersensitivity, and the Human Leukocyte Antigen, HLA-DPB1E(69), is associated with risk of developing CBD. Because inbred strains of mice have not provided good models of CBD to date, three strains of HLA-DPB1 transgenic mice in an FVB/N background were developed; each contains a single allele of HLA-DPB1 that confers a different magnitude of risk for chronic beryllium disease: HLA-DPB1*0401 (OR approximately 0.2), HLA-DPB1*0201 (OR approximately 3), and HLA-DPB1*1701 (OR approximately 46). The mouse ear swelling test (MEST) was employed to determine if these different alleles would support a hypersensitivity response to beryllium. Mice were first sensitized on the back and subsequently challenged on the ear. In separate experiments, mice were placed into one of three groups (sensitization/challenge): C/C, C/Be, and Be/Be. In the HLA-DPB1*1701 mice, the strain with the highest risk transgene, the Be/Be group was the only group that displayed significant maximum increased ear thickness of 19.6% +/- 3.0% over the baseline measurement (p beryllium in seven inbred strains were investigated through use of the MEST, these included: FVB/N, AKR, Balb/c, C3H/HeJ, C57/BL6, DBA/2, and SJL/J. The FVB/N strain was least responsive, while the SJL/J and C57/BL6 strains were the highest responders. Our results suggest that the HLA-DPB1*1701 transgene product is an important risk factor for induction of the beryllium-sensitive phenotype. This model should be a useful tool for investigating beryllium sensitization.

  13. Quantitative determination of fucoidan using polyion-sensitive membrane electrodes.

    Science.gov (United States)

    Kim, Ji Min; Nguyen, Loc; Barr, Mary Frances; Morabito, Michael; Stringer, Damien; Fitton, J Helen; Mowery, Kelly A

    2015-06-02

    The use of polyanion and polycation-sensitive membrane electrodes to detect five different preparations of fucoidan is described. Unlike linear polyanionic molecules previously measured with polymer membrane-based electrochemical sensors, fucoidans from marine brown algae are all highly branched, sulfated polysaccharides with varying charge densities and structures, depending on the species of seaweed, method of extraction used and extent of purification. When tridodecylmethylammonium (TDMA) was used as the ion-exchanger, a large, non-equilibrium EMF response was observed over a concentration range of 0.5-50 μg mL(-1) fucoidan. Fucoidan was also measured by titration with polycationic protamine, using a dinonylnaphthalene sulfonate (DNNS)-doped membrane electrode as the potentiometric endpoint detector. Potentiometric titration was used to determine the binding ratio between protamine and fucoidan at the neutralization endpoint for each fucoidan preparation. This binding ratio was then used to successfully determine the fucoidan content of commercially available nutritional supplements. Fucoidan was also measured in undiluted blood serum, demonstrating that this method may be applicable for measuring fucoidan for clinical applications.

  14. Determination of amantadine and rimantadine using a sensitive fluorescent probe

    Science.gov (United States)

    Wang, Guang-Quan; Qin, Yan-Fang; Du, Li-Ming; Li, Jun-Fei; Jing, Xu; Chang, Yin-Xia; Wu, Hao

    2012-12-01

    Amantadine hydrochloride (AMA) and rimantadine hydrochloride (RIM) are non-fluorescent in aqueous solutions. This property makes their determination through direct fluorescent method difficult. The competing reactions and the supramolecular interaction mechanisms between the two drugs and coptisine (COP) as they fight for occupancy of the cucurbit[7]uril (CB[7]) cavity, were studied using spectrofluorimetry, 1H NMR, and molecular modeling calculations. Based on the significant quenching of the supramolecular complex fluorescence intensity, a fluorescent probe method of high sensitivity and selectivity was developed to determine AMA or RIM in their pharmaceutical dosage forms and in urine samples with good precision and accuracy. The linear range of the method was from 0.0040 to 1.0 μg mL-1 with a detection limit ranging from 0.0012 to 0.0013 μg mL-1. This shows that the proposed method has promising potential for therapeutic monitoring and pharmacokinetics and for clinical application.

  15. REQUIREMENT OF FLUIDITY OF HIGH WATER CONTENT MATERIALS FORTHE GETWAY-SIDE BACKFILLING TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    QiTaiyue; MaNianjie

    1996-01-01

    Through analyzing the effects of water consumption, diameter of solid particle, and flow velocity on the fluidity of high water content material slurry, the relationship among the fluidity, the isotropy of the slurry, and the pumping facilities applied in getway-side backfilling has been found. And the requirment of fluidity of high water content material for the design of getway-side backfilling technique is put forward in the paper.

  16. Microscopic Description of the Granular Fluidity Field in Nonlocal Flow Modeling

    Science.gov (United States)

    Zhang, Qiong; Kamrin, Ken

    2017-02-01

    A recent granular rheology based on an implicit "granular fluidity" field has been shown to quantitatively predict many nonlocal phenomena. However, the physical nature of the field has not been identified. Here, the granular fluidity is found to be a kinematic variable given by the velocity fluctuation and packing fraction. This is verified with many discrete element simulations, which show that the operational fluidity definition, solutions of the fluidity model, and the proposed microscopic formula all agree. Kinetic theoretical and Eyring-like explanations shed insight into the obtained form.

  17. Assessment of fluidity of different invasomes by electron spin resonance and differential scanning calorimetry.

    Science.gov (United States)

    Dragicevic-Curic, Nina; Friedrich, Manfred; Petersen, Silvia; Scheglmann, Dietrich; Douroumis, Dennis; Plass, Winfried; Fahr, Alfred

    2011-06-30

    The aim of this study was to investigate the influence of membrane-softening components (terpenes/terpene mixtures, ethanol) on fluidity of phospholipid membranes in invasomes, which contain besides phosphatidylcholine and water, also ethanol and terpenes. Also mTHPC was incorporated into invasomes in order to study its molecular interaction with phospholipids in vesicular membranes. Fluidity of bilayers was investigated by electron spin resonance (ESR) using spin labels 5- and 16-doxyl stearic acid and by differential scanning calorimetry (DSC). Addition of 1% of a single terpene/terpene mixture led to significant fluidity increase around the C16 atom of phospholipid acyl chains comprising the vesicles. However, it was not possible to differentiate between the influences of single terpenes or terpene mixtures. Incorporation of mTHPC into the bilayer of vesicles decreased fluidity near the C16 atom of acyl chains, indicating its localization in the inner hydrophobic zone of bilayers. These results are in agreement with DSC measurements, which showed that terpenes increased fluidity of bilayers, while mTHPC decreased fluidity. Thus, invasomes represent vesicles with very high membrane fluidity. However, no direct correlation between fluidity of invasomes and their penetration enhancing ability was found, indicating that besides fluidity also other phenomena might be responsible for improved skin delivery of mTHPC.

  18. Microscopic Description of the Granular Fluidity Field in Nonlocal Flow Modeling.

    Science.gov (United States)

    Zhang, Qiong; Kamrin, Ken

    2017-02-03

    A recent granular rheology based on an implicit "granular fluidity" field has been shown to quantitatively predict many nonlocal phenomena. However, the physical nature of the field has not been identified. Here, the granular fluidity is found to be a kinematic variable given by the velocity fluctuation and packing fraction. This is verified with many discrete element simulations, which show that the operational fluidity definition, solutions of the fluidity model, and the proposed microscopic formula all agree. Kinetic theoretical and Eyring-like explanations shed insight into the obtained form.

  19. 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...

  20. 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.

  1. 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

  2. Effect of Heating at Oven-Dry State on Steam Treated Bamboo Powder Thermal Fluidity

    Directory of Open Access Journals (Sweden)

    S. Kajikawa

    2015-01-01

    Full Text Available In hot molding processes of woody material, it is important to understand the effect of oven-dry heating on the property of woody biomass material, such as thermal fluidity. In this study, thermal flow tests of untreated and steam treated bamboo powder were conducted to investigate the effects of heating at an oven-dry state on thermal fluidity. The test temperature was set to 200°C. Before the thermal flow test, powder was dry-heated in a capillary rheometer at 200°C with a variable heating time. Thermogravimetry was conducted to understand the thermal changes of the powder during an increasing temperature and constant temperature. Fluidity of untreated powder was improved with a short dry-heating but decreased with a long dry-heating. In contrast, steam treated powder fluidity was high compared to untreated one, but its fluidity did not improve from dry-heating. From these thermogravimetry results, the chemical changes associated with component volatilization relate with the thermal fluidity. Therefore, the decrease in fluidity from dry-heating occurred because fluidity related components escape from the powder through volatilization.

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

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Jea Myoung; Cho, Myung Sug [KEPCO Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    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

  4. 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.

  5. Fluidity and microstructure formation during flow of Al- SiC particle composites

    Science.gov (United States)

    Yarandi, F. M.; Rohatgi, P. K.; Ray, S.

    1993-06-01

    This article presents the results of casting and spiral fluidity in a Al-7 wt% Si alloy reinforced with 10,15, and 20 vol% SiC particles in permanent molds. The fluidity of the Al-SiC slurry increases linearly with temperature up to about 760 °C. Above this temperature, the casting fluidity of the Al-SiC particle slurry does not change significantly with an increase in temperature. In several cases, the fluidity decreased at temperatures above 760 °C. The fluidity of Al-SiC melts containing 9-μm SiC particles decreased with an increase in volume percentage of SiC up to 15 vol% (the range studied), presumably due to an increase in the viscosity of the melt with increasing volume percentage of dispersoid and changes in thermophysical properties of the composite. However, the fluidity of Al-20 vol% SiC of 14-μm particle size is higher than the fluidity of Al-15 vol% SiC 9-μm particles, indicating the role of particle size and surface area in de-creasing fluidity. Composite slurries travel farther in a channel of larger cross sections compared to channels of smaller cross sections under similar conditions. Casting fluidity increases linearly with an in-crease in cross section of the channel. A model has been proposed to calculate the values of fluidity of the composite as a function of particle volume percent, superheat, flow velocity of the melt, and the cross sec-tion of the flow channel. Experimental observations have been compared with the predictions of the model, and some deviations have been attributed to settling and segregation of SiC particles observed through microstructural examination.

  6. To deal with fluidity in the networked society

    DEFF Research Database (Denmark)

    Levinsen, Karin Tweddell

    2010-01-01

    designs for teaching and learning for that purpose. We need research that aims to describe the phenomenology of acquiring digital literacy and self-programming in order to be able to identify relevant learning objectives and scaffolding. Findings from such studies are expected to be relevant for e......, 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...... about how we may get there. In the educational system ICT and e-learning are becoming an everyday condition and the basic challenge for the educational system is twofold: 1) The actually making of digital literate and self-programming social actors – students and teachers; and 2) How to develop adequate...

  7. 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 i

  8. Carbon dots based fluorescent sensor for sensitive determination of hydroquinone.

    Science.gov (United States)

    Ni, Pengjuan; Dai, Haichao; Li, Zhen; Sun, Yujing; Hu, Jingting; Jiang, Shu; Wang, Yilin; Li, Zhuang

    2015-11-01

    In this paper, a novel biosensor based on Carbon dots (C-dots) for sensitive detection of hydroquinone (H2Q) is reported. It is interesting to find that the fluorescence of the C-dots could be quenched by H2Q directly. The possible quenching mechanism is proposed, which shows that the quenching effect may be caused by the electron transfer from C-dots to oxidized H2Q-quinone. Based on the above principle, a novel C-dots based fluorescent probe has been successfully applied to detect H2Q. Under the optimal condition, detection limit down to 0.1 μM is obtained, which is far below U.S. Environmental Protection Agency estimated wastewater discharge limit of 0.5 mg/L. Moreover, the proposed method shows high selectivity for H2Q over a number of potential interfering species. Finally, several water samples spiked with H2Q are analyzed utilizing the sensing method with satisfactory recovery. The proposed method is simple with high sensitivity and excellent selectivity, which provides a new approach for the detection of various analytes that can be transformed into quinone.

  9. Implementing hybrid MPI/OpenMP parallelism in Fluidity

    Science.gov (United States)

    Gorman, Gerard; Lange, Michael; Avdis, Alexandros; Guo, Xiaohu; Mitchell, Lawrence; Weiland, Michele

    2014-05-01

    Parallelising finite element codes using domain decomposition methods and MPI has nearly become routine at the application code level. This has been helped in no small part by the development of an eco-system of open source libraries to provide key functionality, for example SCOTCH for graph partitioning or PETSc for sparse iterative solvers. As we move to an era where pure MPI no longer suffices, application developers cannot only focus on the application code, but must consider the full software stack. In the case of Fluidity (an open source control volume/finite element general purpose fluid dynamics code) the decision to improve parallel efficiency by moving to a hybrid MPI/OpenMP programming model it became necessary to get involved in extending 3rd party open source libraries, specifically PETSc, in addition to the application code itself. The effort involved in re-engineering a large application code highlights the fact that as computing platforms continue their advance towards low power many core processors, the software stack must also develop at a similar pace or application codes will suffer. In this presentation we will illustrate the steps required to re-engineer Fluidity to achieve good parallel efficiency when using MPI/OpenMP. We identify performance pitfalls when using Fortran features such as automatic arrays in a multi-threaded context, as well as poor data locality on NUMA platforms. A significant proportion of the computational cost is in the sparse iterative solvers. For this we collaborated with the development team at Argonne National Laboratory to add OpenMP support to PETSc. We will present performance results for both the application as a whole, as well as for key individual components such as matrix assembly and the solvers. We also show that while we did not explicitly target I/O for optimisation here, its performance is nonetheless greatly improved because of fewer processes accessing the file system. One of the main remaining

  10. Sensitive Determination of DNA by RLS Enhancement of Metal Ions

    Institute of Scientific and Technical Information of China (English)

    Huang Jian-ping; Chen Fang; Ai Xin-ping; He Zhi-ke

    2004-01-01

    The interactions between metal ions and DNA have been studied by the resonance light scattering (RLS) spectra. In the acidic condition, the RLS signals of metal ions, especially the transition metal ions in group ⅠB and ⅡB, were increased by DNA. And it is found that the enhancement of RLS signals is linear to the concentration of DNA, so the RLS method for DNA determination was proposed in the presence of Cu2+. On the optimum conditions, the linear range and the detect limit of ctDNA is 4×10-8-4×10-6 g·5mL-1 and 1.13×10-8 g·5mL-1, respectively. The proposed method is successfully applied to determine the extracted plasmid DNA of Bacillus subtilis DB104.

  11. 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 skin sensitisation above and below the LogKow = 1 threshold. Reaction chemistry considerations could explain the skin sensitisation observed for the 38 sensitisers with a LogKow 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

  12. 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...

  13. Sensitive spectrophotometric determination of aluminium using thermal lens spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, R.D.; Snook, R.D. (Manchester Univ. (United Kingdom). Inst. of Science and Technology)

    1991-10-01

    The determination of Al{sup 3=} in solution using a continuous-wave mode mismatched thermal lens spectrometer is reported and two spectro-photometric procedures are compared. The reagent systems investigated were bromopyrogallol red-tetradecyltrimethylammonium bromide (BPR-TDTA) and chrome azurol S-cetylpyridinium chloride (CAS-CPC). The CAS-CPC system gave a superior detection limit (0.17 {mu}g l{sup -1}) to the BPR-TDTA system (1.15 mg l{sup -1}) owing to the higher reagent blanks and concomitant laser noise in the latter system. (author). 24 refs.; 6 figs.; 2 tabs.

  14. Lipophilic Contaminants Influence Cold Tolerance of Invertebrates through Changes in Cell Membrane Fluidity

    DEFF Research Database (Denmark)

    Holmstrup, Martin; Bouvrais, Hélène; Westh, Peter

    2014-01-01

    temperatures of organisms that cannot regulate their body temperature (ectotherms) depends on their ability to increase the fluidity of their cellular membranes at low temperatures. Our study shows that contaminants accumulating in lipids of organisms alter the physical state of their membranes simply by being...... present. Contaminants of varying chemical structures can alter the membrane fluidity in either direction and correspondingly modulate the cold tolerance of intact animals....

  15. Sexual Fluidity and Related Attitudes and Beliefs Among Young Adults with a Same-Gender Orientation.

    Science.gov (United States)

    Katz-Wise, Sabra L; Hyde, Janet S

    2015-07-01

    Little research has examined whether experiencing sexual fluidity--changes over time in attractions and sexual orientation identity--is related to specific cognitions. This study explored attitudes and beliefs among sexually fluid and non-sexually fluid individuals and developed two new measures of sexuality beliefs based on Diamond's sexual fluidity research and Dweck's psychological theory of intelligence beliefs. Participants were 188 female and male young adults in the United States with a same-gender orientation, ages 18-26 years. Participants completed an online questionnaire which assessed sexual fluidity in attractions and sexual orientation identity, attitudes toward bisexuality, sexuality beliefs, and demographics. Sexual fluidity in attractions was reported by 63 % of females and 50 % of males, with 48 % of those females and 34 % of those males reporting fluidity in sexual orientation identity. No significant gender differences in frequency of sexual fluidity were observed. Sexually fluid females had more positive attitudes toward bisexuality than non-sexually fluid females; however, no significant difference was observed for males. Females were more likely than males to endorse sexual fluidity beliefs and to believe that sexuality is changeable; and sexually fluid persons were more likely than non-sexually fluid persons to hold those two beliefs. Among males, non-sexually fluid individuals were more likely than sexually fluid individuals to believe that sexuality is something an individual is born with. Females were more likely than males to endorse the belief that sexuality is influenced by the environment. Findings from this research link sexual fluidity with specific cognitions.

  16. Determining confounding sensitivities in eddy current thin film measurements

    Science.gov (United States)

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

    2017-02-01

    Eddy current (EC) techniques are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done by 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 was 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 was 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 was 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-loaded eddy probe was at measuring film thickness under varying experimental conditions. This research studied the effects of a number of factors such as i) conductivity, ii) edge effect, iii) surface finish of base material and iv) cable condition.

  17. Cytoskeletal stiffness, friction, and fluidity of cancer cell lines with different metastatic potential.

    Science.gov (United States)

    Coughlin, Mark F; Bielenberg, Diane R; Lenormand, Guillaume; Marinkovic, Marina; Waghorne, Carol G; Zetter, Bruce R; Fredberg, Jeffrey J

    2013-03-01

    We quantified mechanical properties of cancer cells differing in metastatic potential. These cells included normal and H-ras-transformed NIH3T3 fibroblast cells, normal and oncoprotein-overexpressing MCF10A breast cancer cells, and weakly and strongly metastatic cancer cell line pairs originating from human cancers of the skin (A375P and A375SM cells), kidney (SN12C and SN12PM6 cells), prostate (PC3M and PC3MLN4 cells), and bladder (253J and 253JB5 cells). Using magnetic twisting cytometry, cytoskeletal stiffness (g') and internal friction (g″) were measured over a wide frequency range. The dependencies of g' and g″ upon frequency were used to determine the power law exponent x which is a direct measure of cytoskeletal fluidity and quantifies where the cytoskeleton resides along the spectrum of solid-like (x = 1) to fluid-like (x = 2) states. Cytoskeletal fluidity x increased following transformation by H-ras oncogene expression in NIH3T3 cells, overexpression of ErbB2 and 14-3-3-ζ in MCF10A cells, and implantation and growth of PC3M and 253J cells in the prostate and bladder, respectively. Each of these perturbations that had previously been shown to enhance cancer cell motility and invasion are shown here to shift the cytoskeleton towards a more fluid-like state. In contrast, strongly metastatic A375SM and SN12PM6 cells that disseminate by lodging in the microcirculation of peripheral organs had smaller x than did their weakly metastatic cell line pairs A375P and SN12C, respectively. Thus, enhanced hematological dissemination was associated with decreased x and a shift towards a more solid-like cytoskeleton. Taken together, these results are consistent with the notion that adaptations known to enhance metastatic ability in cancer cell lines define a spectrum of fluid-like versus solid-like states, and the position of the cancer cell within this spectrum may be a determinant of cancer progression.

  18. Effect of biodiesels blending on their low-temperature fluidity%生物柴油调合对其低温流动性能的改善

    Institute of Scientific and Technical Information of China (English)

    吕涯; 李骏; 欧阳福生

    2011-01-01

    为了了解生物柴油中脂肪酸甲酯组成对其低温流动性能的影响,探索改善其流动性能的方法,以大豆油、花生油和牛油为原料合成了大豆油甲酯、花生油甲酯和牛油甲酯,测定了它们的脂肪酸甲酯组成和低温流动性能.结果表明,长碳链饱和脂肪酸甲酯的含量是影响生物柴油低温流动性能的主要因素.通过对混合生物柴油流动性能的测定,发现可以通过不同来源生物柴油的调合改善其流动性能.对于一些高倾点生物柴油,通过油品调合改善低温流动性能的效果比添加石化柴油降凝剂的效果明显.此外,通过偏振光显微镜观察生物柴油的结晶形态,分析了脂肪酸甲酯的结晶机理.%In order to know the influence of the composition of fatty acid methyl ester (FAME) on the lowtemperature fluidity of biodiesel, and to find the way to improve it, the soybean oil methyl ester, peanut oil methyl ester and tallow oil methyl ester were synthesized from soybean oil, peanut oil and tallow oil.Their FAME composition and low-temperature fluidity have been determined.The results show that saturated long chain FAMEs are the main reason to influence the fluidity of biodiesel.The fluidity of biodiesel blends suggests that mixing FAMEs from different sources would decrease its pour point (PP) and cold filter plugging point (CFPP).The improvement of fluidity by blending is greater than that of adding fluidity improver into high-PP biodiesels.Furthermore, the mechanism of crystallization of FAME was analyzed by observation from polarized light microscope.

  19. 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.

  20. Portable High Sensitivity and High Resolution Sensor to Determine Oxygen Purity Levels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I STTR project is to develop a highly sensitive oxygen (O2) sensor, with high accuracy and precision, to determine purity levels of high...

  1. 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

  2. VLDL lipolysis products increase VLDL fluidity and convert apolipoprotein E4 into a more expanded conformation.

    Science.gov (United States)

    Tetali, Sarada D; Budamagunta, Madhu S; Simion, Catalina; den Hartigh, Laura J; Kálai, Tamás; Hideg, Kálmán; Hatters, Danny M; Weisgraber, Karl H; Voss, John C; Rutledge, John C

    2010-06-01

    Our previous work indicated that apolipoprotein (apo) E4 assumes a more expanded conformation in the postprandial period. The postprandial state is characterized by increased VLDL lipolysis. In this article, we tested the hypothesis that VLDL lipolysis products increase VLDL particle fluidity, which mediates expansion of apoE4 on the VLDL particle. Plasma from healthy subjects was collected before and after a moderately high-fat meal and incubated with nitroxyl-spin labeled apoE. ApoE conformation was examined by electron paramagnetic resonance spectroscopy using targeted spin probes on cysteines introduced in the N-terminal (S76C) and C-terminal (A241C) domains. Further, we synthesized a novel nitroxyl spin-labeled cholesterol analog, which gave insight into lipoprotein particle fluidity. Our data revealed that the order of lipoprotein fluidity was HDL approximately LDLfluidity, VLDL lipolysis products significantly altered apoE4 into a more expanded conformation. Our studies indicate that after every meal, VLDL fluidity is increased causing apoE4 associated with VLDL to assume a more expanded conformation, potentially enhancing the pathogenicity of apoE4 in vascular tissue.

  3. 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.

  4. Thyroid hormone determines the start of the sensitive period of imprinting and primes later learning.

    Science.gov (United States)

    Yamaguchi, Shinji; Aoki, Naoya; Kitajima, Takaaki; Iikubo, Eiji; Katagiri, Sachiko; Matsushima, Toshiya; Homma, Koichi J

    2012-01-01

    Filial imprinting in precocial birds is the process of forming a social attachment during a sensitive or critical period, restricted to the first few days after hatching. Imprinting is considered to be part of early learning to aid the survival of juveniles by securing maternal care. Here we show that the thyroid hormone 3,5,3'-triiodothyronine (T(3)) determines the start of the sensitive period. Imprinting training in chicks causes rapid inflow of T(3), converted from circulating plasma thyroxine by Dio2, type 2 iodothyronine deiodinase, in brain vascular endothelial cells. The T(3) thus initiates and extends the sensitive period to last more than 1 week via non-genomic mechanisms and primes subsequent learning. Even in non-imprinted chicks whose sensitive period has ended, exogenous T(3) enables imprinting. Our findings indicate that T(3) determines the start of the sensitive period for imprinting and has a critical role in later learning.

  5. Buyang Huanwu decoction enhances cell membrane fluidity in rats with cerebral ischemia/reperfusion

    Institute of Scientific and Technical Information of China (English)

    Chenxu Li

    2012-01-01

    After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct patho-logical changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membrane fluidity significantly decreased in ischemia/reperfusion rats as detected by spin-labeling electron spin resonance, consistent with order parameter S and rotational correlation time TC measurements. Brain nerve cells from rats with ischemia/reperfusion injury were cultured with 1-100 mg/mL Buyang Huanwu decoction. Results showed that Buyang Huanwu decoction gradually increased membrane fluidity dose-dependently to normal levels, and eliminated hydroxide (OH·) and superoxide (O2·) free radicals dose-dependently. These findings suggest that Buyang Huanwu decoction can protect against cell membrane fluidity changes in rats with ischemia/ reper-fusion injury by scavenging free radicals.

  6. 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....

  7. Determining importance weighting functions for Contributon theory eigenvalue sensitivity coefficient methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Perfetti, C.; Martin, W. [Univ. of Michigan, Dept. of Nuclear Engineering and Radiological Sciences, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109-2104 (United States); Rearden, B.; Williams, M. [Oak Ridge National Laboratory, Reactor and Nuclear Systems Div., Bldg. 5700, P.O. Box 2008, Oak Ridge, TN 37831-6170 (United States)

    2012-07-01

    This study introduced two new approaches for calculating the F*(r) importance weighting function for Contributon and CLUTCH eigenvalue sensitivity coefficient calculations, and compared them in terms of accuracy and applicability. The necessary levels of F*(r) mesh refinement and mesh convergence for obtaining accurate eigenvalue sensitivity coefficients were determined for two preliminary problems through two parametric studies, and the results of these studies suggest that a sufficiently accurate F*(r) mesh for calculating eigenvalue sensitivity coefficients can be obtained for these problems with only a small increase in problem runtime. (authors)

  8. Determining Importance Weighting Functions for Contributon Theory Eigenvalue Sensitivity Coefficient Methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Perfetti, Christopher M [ORNL; Martin, William R [University of Michigan; Rearden, Bradley T [ORNL; Williams, Mark L [ORNL

    2012-01-01

    This study introduced three approaches for calculating the importance weighting function for Contributon and CLUTCH eigenvalue sensitivity coefficient calculations, and compared them in terms of accuracy and applicability. The necessary levels of mesh refinement and mesh convergence for obtaining accurate eigenvalue sensitivity coefficients were determined through two parametric studies, and the results of these studies suggest that a sufficiently-accurate mesh for calculating eigenvalue sensitivity coefficients can be obtained for the Contributon and CLUTCH methods with only a small increase in problem runtime.

  9. The Effect of Copper Addition on the Fluidity and Viscosity of an Al-Mg-Si Alloy

    Science.gov (United States)

    Heidarzadeh, A.; Emamy, M.; Rahimzadeh, A.; Soufi, R.; Sohrabi Baba Heidary, D.; Nasibi, Sh.

    2013-12-01

    This study was undertaken to investigate the effect of Cu addition on the fluidity and viscosity of Al-%15Mg2Si in-situ metal matrix composite. The flowability of the composites was studied by measuring strip fluidity, cast in a permanent mold. The effect of casting parameters such as casting and mold temperatures on fluidity was studied. After obtaining an optimum condition for casting and mold temperatures, the effect of Cu addition on the fluidity and viscosity was studied. DSC thermal analysis was applied for studying the effect of Cu on solidification characteristics. Also, composites were characterized by optical and scanning electron microscopy (SEM). The results showed that casting fluidity of composites increases with the increase of mold and melt temperatures, but decreases with increase of Cu addition. Similarly, the viscosity of composites was increased by adding Cu content. The main effect of Cu was on the solidification mode.

  10. 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.

  11. Effect of butanol on lipid composition and fluidity of Clostridium acetobutylicum ATCC 824.

    OpenAIRE

    Vollherbst-Schneck, K; Sands, J A; Montenecourt, B S

    1984-01-01

    Butanol, at sub-growth-inhibitory levels, caused a ca. 20 to 30% increase in fluidity of lipid dispersions from Clostridium acetobutylicum. When grown in the presence of butanol or into stationary phase, C. acetobutylicum synthesized increased levels of saturated acyl chains at the expense of unsaturated chains.

  12. 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.

  13. 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.

  14. Application of the compensated Arrhenius formalism to fluidity data of polar organic liquids.

    Science.gov (United States)

    Petrowsky, Matt; Fleshman, Allison M; Frech, Roger

    2013-03-14

    The temperature dependence of viscosity (the reciprocal of fluidity) in polar liquids has been studied for over a century, but the available theoretical models have serious limitations. Consequently, the viscosity is often described with empirical equations using adjustable fitting parameters that offer no insight into the molecular mechanism of transport. We have previously reported a novel approach called the compensated Arrhenius formalism (CAF) to describe ionic conductivity, self-diffusion, and dielectric relaxation in terms of molecular and system properties. Here the CAF is applied to fluidity data of pure n-acetates, 2-ketones, n-nitriles, and n-alcohols over the temperature range 5-85 °C. The fluidity is represented as an Arrhenius-like expression that includes a static dielectric constant dependence in the exponential prefactor. The dielectric constant dependence results from the dependence of mass and charge transport on the molecular dipole moment and the solvent dipole density. The CAF is the only self-consistent description of fluid transport in polar liquids written solely in terms of molecular and system parameters. A scaling procedure is used to calculate the activation energy for transport. We find that the activation energies for fluidity of the aprotic liquids are comparable in value, whereas a higher average E(a) value is observed for the n-alcohol data. Finally, we contrast the molecular description of transport presented here with the conventional hydrodynamic model.

  15. Rigidity and Fluidity in Living and Nonliving Matter

    Science.gov (United States)

    Lopez, Jorge H.

    complicated problem of jamming, we will gain insight into which constraints affect the nature of the jamming transition and which do not. We find that k = 3-core percolation on the hyperbolic lattice remains a continuous phase transition despite the fact that the loop structure of hyperbolic lattices is different from Euclidean lattices. We also contribute towards numerical techniques for analyzing percolation on hyperbolic lattices. In Chapters 4 and 5 we turn to living matter, which is also nonequilibrium in a very local way in that each constituent has its own internal energy supply. In Chapter 4 we study the fluidity of a cell moving through a confluent tissue, i.e. a group of cells with no gaps between them, via T1 transitions. A T1 transition allows for an edge swap so that a cell can come into contact with new neighbors. Cell migration is then generated by a sequence of such swaps. In a simple four cell system we compute the energy barriers associated with this transition. We then find that the energy barriers in a larger system are rather similar to the four cell case. The many cell case, however, more easily allows for the collection of statistics of these energy barriers given the disordered packings of cell observed in experiments. We find that the energy barriers are exponentially distributed. Such a finding implies that glassy dynamics is possible in a confluent tissue. Finally, in chapter 5 we turn to single cell migration in the extracellular matrix, another native environment of a cell. Experiments suggest that the migration of some cells in the three-dimensional extra cellular matrix bears strong resemblance to one-dimensional cell migration. Motivated by this observation, we construct and study a minimal one-dimensional model cell made of two beads and an active spring moving along a rigid track. The active spring models the stress fibers with their myosin-driven contractility and alpha-actinin-driven extendability, while the friction coefficients of the two

  16. The interaction between human low density lipoproteins and bovine aortic endothelial cells. Measurements of membrane fluidity.

    Science.gov (United States)

    Badea, M G; Sima, A; Jinga, V V; Hörer, O

    1989-01-01

    Bovine aortic endothelial cells in culture have been incubated with human low density lipoproteins (LDL) characterized in their cholesterol content. The incubation was done at different time intervals up to 72 h and various LDL concentrations. It began after endothelial cells had been starved for 24 h in lipoprotein deficient serum. The transfer of some LDL-components to endothelial cells plasmalemma was monitored by measurements of membrane fluidity. Namely, the fluorescent probe trimethylamonio-diphenyl hexatriene was inserted in the cell membrane and fluorescence anisotropy was determined; a higher fluorescence anisotropy means a higher rigidity of the plasmalemma. The results show that the rigidity of the endothelial cell plasmalemma increased progressively with the time of incubation (+11% to +19.5% after 24 h and 72 h, respectively for the concentration of 200 micrograms. LDL-cholesterol/dish) and with the greater amount of cholesterol in LDL (+10.9%) for 200 micrograms LDL-cholesterol/dish to +15% for 800 micrograms LDL-cholesterol/dish after 24 h incubation). In order to see if the LDL material transfer proceeded by receptor-mediated endocytosis of LDL and/or directly through aqueous solution a lysosomal inhibitor, chloroquine, was used at the concentration of 20 microM for preventing the lysosomal hydrolase activity. In the presence of this inhibitor the fluorescence anisotropy in treated endothelial cells increased by a lesser amount, suggesting an approx. 30% participation of intracellular route. Therefore, the transfer of material (probably cholesterol) from LDL to endothelial plasmalemma could take place both by receptor-mediated endocytosis and directly through the aqueous solution.

  17. 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

  18. Effect of changes in the composition of cellular fatty acids on membrane fluidity of Rhodobacter sphaeroides.

    Science.gov (United States)

    Kim, Eui-Jin; Lee, Jeong K

    2015-02-01

    The cellular fatty acid composition is important for metabolic plasticity in Rhodobacter sphaeroides. We explored the effects of changing the cellular ratio of unsaturated fatty acids (UFAs) to saturated fatty acids (SFAs) in R. sphaeroides by overexpressing several key fatty acid biosynthetic enzymes through the use of expression plasmid pRK415. Bacteria containing the plasmid pRKfabI1 with the fabI1 gene that encodes enoyl-acyl carrier protein (ACP) reductase showed a reduction in the cellular UFA to SFA ratio from 4 (80% UFA) to 2 (65% UFA) and had decreased membrane fluidity and reduced cell growth. Additionally, the ratio of UFA to SFA of the chromatophore vesicles from pRKfabI1 -containing cells was similarly lowered, and the cell had decreased levels of light-harvesting complexes, but no change in intracytoplasmic membrane (ICM) content or photosynthetic (PS) gene expression. Both inhibition of enoyl- ACP reductase with diazaborine and addition of exogenous UFA restored membrane fluidity, cell growth, and the UFA to SFA ratio to wild-type levels in this strain. R. sphaeroides containing the pRKfabB plasmid with the fabB gene that encodes the enzyme β-ketoacyl-ACP synthase I exhibited an increased UFA to SFA ratio from 4 (80% UFA) to 9 (90% UFA), but showed no change in membrane fluidity or growth rate relative to control cells. Thus, membrane fluidity in R. sphaeroides remains fairly unchanged when membrane UFA levels are between 80% and 90%, whereas membrane fluidity, cell growth, and cellular composition are affected when UFA levels are below 80%.

  19. Determination of Mass Sensitivity of Crystal Quartz Resonators at Students' Laboratory

    Science.gov (United States)

    Greczylo, Tomasz; Mazur, Piotr; Debowska, Ewa; Wieczorek, Piotr

    2010-01-01

    This paper presents an experiment in which students determine the mass sensitivity of three crystal quartz resonators, designed to be carried out in "Physics Laboratory II" at the Institute of Experimental Physics, University of Wroclaw. The authors discuss the process of setting up the experiment and the results of the measurements. They clearly…

  20. Determination of Mass Sensitivity of Crystal Quartz Resonators at Students' Laboratory

    Science.gov (United States)

    Greczylo, Tomasz; Mazur, Piotr; Debowska, Ewa; Wieczorek, Piotr

    2010-01-01

    This paper presents an experiment in which students determine the mass sensitivity of three crystal quartz resonators, designed to be carried out in "Physics Laboratory II" at the Institute of Experimental Physics, University of Wroclaw. The authors discuss the process of setting up the experiment and the results of the measurements.…

  1. A rapid method for determining salinomycin and monensin sensitivity in Eimeria tenella

    Science.gov (United States)

    Standard methods of determining the ionophore sensitivity of Eimeria rely on infecting chickens with an isolate or a mixture of Eimeria spp. oocysts in the presence of different anti-coccidial drugs. The purpose of this study was to develop a rapid in vitro method for assessing salinomycin and mone...

  2. 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...

  3. 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...

  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. SENSE shimming (SSH): A fast approach for determining B(0) field inhomogeneities using sensitivity coding.

    Science.gov (United States)

    Splitthoff, D N; Zaitsev, M

    2009-11-01

    The pursuit of ever higher field strengths and faster data acquisitions has led to the construction of coil arrays with high numbers of elements. With the sensitivity encoding (SENSE) technique, it has been shown that the sensitivity of those elements can be used for spatial image encoding. Here, a proof-of-principle is presented of a method that can be considered an extreme case of the SENSE approach, completely abstaining from using encoding gradients. The resulting sensitivity encoded free-induction decay (FID) data are then not used for imaging, but for determining B(0) field inhomogeneity distribution. The method has therefore been termed "SENSE shimming" (SSH). In phantom experiments the method's ability to detect inhomogeneities of up to the second order is demonstrated.

  8. Simultaneous determination of 4-nitroanisole, 4-nitrophenol, and 4-nitrocatechol by phase-sensitive ac polarography.

    Science.gov (United States)

    Burgschat, H; Netter, K J

    1977-01-01

    Phase-sensitive ac polarography was applied to the simultaneous quantitative determination of 4-nitroanisole, 4-nitrophenol, and 4-nitrocatechol in alkaline solutions. Certain experimental precautions are necessary to determine each compound in the presence of the other two. Thus, 4-nitrocatechol is determined indirectly by forming a yellow ratio chelate with cupric ions, wheras 4-nitroansole is determined directly by the reduction waves of the nitro group. For the determination of 4-nitrophenol, the interferency by the simultaneously present 4-nitrocatechol must be eliminated by masking it by the addition of magnesium ions. The method described permits a qualitative and quantitative analysis of all three compounds in one solution since linear calibration curves are obtained.

  9. An assay to determine the sensitive window of embryos to chemical exposure using Xenopus tropicalis.

    Science.gov (United States)

    Hu, Lingling; Wu, Lijiao; Xue, Yingang; Zhu, Jingmin; Shi, Huahong

    2016-05-01

    The frog embryo teratogenesis assay-Xenopus (FETAX) is an established method to evaluate the developmental toxicity of chemicals. In FETAX, a 48 h continuous exposure is usually conducted when the X. tropicalis embryo is used as the test model. In the present study, we exposed X. tropicalis embryos to nine known teratogens for four separate 12-h periods. The embryos showed great variations in response to nine tested compounds during different exposure periods. Based on the value of the score of malformations, the most sensitive 12 h exposure periods of embryos were significantly distinguished for all the compounds with the exception of NiCl2 . The embryos were the most sensitive to retinols (e.g. all-trans-retinoic acid and 9-cis-retinoic acid) during 0-12 h and to metal compounds (e.g. triphenlytin and CdCl2) during a 24 to 36 h exposure period. In the further 3 h exposure experiment, the most sensitive period could only be determined for one of three tested compounds. Based on the present results, we proposed an assay to determine a 12 h sensitive window of embryos to chemical exposure using Xenopus tropicalis.

  10. Determination of Mass Spectrometric Sensitivity of Different Metalloporphyrin Esters Relative to Porphyrin Ester

    DEFF Research Database (Denmark)

    Larsen, Elfinn; Egsgaard, Helge; Møller, J.

    1977-01-01

    Quantitative determination of metalloporphyrin contamination in preparations of biologically important porphyrins was achieved mass spectrometrically by application of the integrated ion current technique. For this purpose, the relative molecular ion sensitivities of the contaminating metal compl...... complexes were determined from the ratios of the integrated molecular ion currents of a series of calibration samples containing a porphyrin ester and one of its metal complexes in known molar ratio. Complexes formed with divalent ions of Cu, Zn, Fe, Co and Ni of copro- as well as uro......-prophyrin permethylester were all found to have the same molecular ion sensitivities as their metal-free porphyrin ester. The relative metalloporphyrin ester content in a sample of porphyrin ester was thus obtained directly as the integrated ion current ratios of the normalized molecular ions. The preparation...

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

    Science.gov (United States)

    Liang, Xing-xin; Li, Fan; Gao, Feng; Li, Chun-xiao; Qiao, Xiao-hui; Zhang, Jia-jie; Du, Lian-fang

    2016-01-01

    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 elastic modulus 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.

  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.

  13. Methyl-β-Cyclodextrin /Cetyltrimethyl Ammonium Bromide Synergistic Sensitized Fluorescence Method for the Determination of Levofloxacin.

    Science.gov (United States)

    Ren, Qiuyi; Zhu, Xiashi

    2016-03-01

    A novel method of methyl-β-cyclodextrin (methyl-β-CD) and cetyltrimethyl ammonium bromide (CTAB) synergistic sensitized fluorescence analysis to determine levofloxacin (LVFX) was developed. The results were shown that the fluorescence intensity of LVFX was increased a lot in the system of methyl-β-cyclodextrin-CTAB medium. Under the conditions of λ(ex/em )= 330/507 nm and pH 4.5, the linear range and the detection limit for LVFX were found to be 0.040 ~ 4.0 μg/mL and 0.3 ng/mL, respectively. The mechanism of sensitized fluorescence method was discussed by the solubilization capacity and the microenvironment of medium. The proposed method has been applied for the determination of LVFX in eye drops real samples and human serum with satisfactory recovery.

  14. 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.

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

    OpenAIRE

    Xing-xin Liang; Fan Li; Feng Gao; Chun-xiao Li; Xiao-hui Qiao; Jia-jie Zhang; Lian-fang Du

    2016-01-01

    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 parathyr...

  16. Numerical modelling of the thermal and fluid flow phenomena of the fluidity test

    Directory of Open Access Journals (Sweden)

    A. Bokota

    2010-01-01

    Full Text Available In the paper, two mathematical models of the solidification of a cylindrical shaped casting, which take into account the process of filling the mould cavity with molten metal during the vertical fluidity test, has been proposed. In the general model, velocity and pressure fields were obtained by solving the momentum equations and the continuity equation, whereas the thermal fields were obtained by solving the heat conduction equation containing the convection term. In the simplified model, making assumptions relating to both the material and the geometry of the region, the general equations for continuity and momentum have been reduced to single equation for pressure. This approach leads as to accelerate significantly of the fluid flow calculations. In this model, coupling of the thermal 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 problem has been solved by the finite element method.

  17. Phenothiazines Inhibit Hepatitis C Virus Entry, Likely by Increasing the Fluidity of Cholesterol-Rich Membranes

    Science.gov (United States)

    Chamoun-Emanuelli, Ana M.; Pecheur, Eve-Isabelle; Simeon, Rudo L.; Huang, Da; Cremer, Paul S.

    2013-01-01

    Despite recent progress in the development of direct-acting antiviral agents against hepatitis C virus (HCV), more effective therapies are still urgently needed. We and others previously identified three phenothiazine compounds as potent HCV entry inhibitors. In this study, we show that phenothiazines inhibit HCV entry at the step of virus-host cell fusion, by intercalating into cholesterol-rich domains of the target membrane and increasing membrane fluidity. Perturbation of the alignment/packing of cholesterol in lipid membranes likely increases the energy barrier needed for virus-host fusion. A screening assay based on the ability of molecules to selectively increase the fluidity of cholesterol-rich membranes was subsequently developed. One compound that emerged from the library screen, topotecan, is able to very potently inhibit the fusion of liposomes with cell culture-derived HCV (HCVcc). These results yield new insights into HCV infection and provide a platform for the identification of new HCV inhibitors. PMID:23529728

  18. Effect of gold nanoparticle on structure and fluidity of lipid membrane.

    Directory of Open Access Journals (Sweden)

    Anil R Mhashal

    Full Text Available This paper deals with the effect of different size gold nanoparticles on the fluidity of lipid membrane at different regions of the bilayer. To investigate this, we have considered significantly large bilayer leaflets and incorporated only one nanoparticle each time, which was subjected to all atomistic molecular dynamics simulations. We have observed that, lipid molecules located near to the gold nanoparticle interact directly with it, which results in deformation of lipid structure and slower dynamics of lipid molecules. However, lipid molecules far away from the interaction site of the nanoparticle get perturbed, which gives rise to increase in local ordering of the lipid domains and decrease in fluidity. The bilayer thickness and area per head group in this region also get altered. Similar trend, but with different magnitude is also observed when different size nanoparticle interact with the bilayer.

  19. Effect of Gold Nanoparticle on Structure and Fluidity of Lipid Membrane

    Science.gov (United States)

    Mhashal, Anil R.; Roy, Sudip

    2014-01-01

    This paper deals with the effect of different size gold nanoparticles on the fluidity of lipid membrane at different regions of the bilayer. To investigate this, we have considered significantly large bilayer leaflets and incorporated only one nanoparticle each time, which was subjected to all atomistic molecular dynamics simulations. We have observed that, lipid molecules located near to the gold nanoparticle interact directly with it, which results in deformation of lipid structure and slower dynamics of lipid molecules. However, lipid molecules far away from the interaction site of the nanoparticle get perturbed, which gives rise to increase in local ordering of the lipid domains and decrease in fluidity. The bilayer thickness and area per head group in this region also get altered. Similar trend, but with different magnitude is also observed when different size nanoparticle interact with the bilayer. PMID:25469786

  20. Sensitized effect of β-cyclodextrin on the fluorescence in the determination of carbaryl

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-li; TANG Bo

    2004-01-01

    Based on the significant enhancement of fluorescence intensity of carbaryl in inclusion complex, a spetrofluorimetric method with high sensitivity was developed for the determination of carbaryl in aqueous solution. Under the optimum conditions, the complex had excitation and emission maxima at 278 nm and 332 nm, respectively. The linear range of the method was 7.0 ng/ml-1500 ng/ml with a detection limit of 1.2 ng/ml. The proposed method was successfully used to determine quantitatively of carbaryl in cottonseeds.

  1. 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

  2. The Effect of Lidocaine · HCl on the Fluidity of Native and Model Membrane Lipid Bilayers

    OpenAIRE

    Park, Jun-Seop; Jung, Tae-Sang; Noh, Yang-Ho; Kim, Woo-Sung; Park, Won-Ick; Kim, Young-Soo; Chung, In-Kyo; Sohn, Uy Dong; Bae, Soo-Kyung; Bae, Moon-Kyoung; Jang, Hye-Ock; Yun, Il

    2012-01-01

    The purpose of this study is to investigated the mechanism of pharmacological action of local anesthetic and provide the basic information about the development of new effective local anesthetics. Fluorescent probe techniques were used to evaluate the effect of lidocaine·HCl on the physical properties (transbilayer asymmetric lateral and rotational mobility, annular lipid fluidity and protein distribution) of synaptosomal plasma membrane vesicles (SPMV) isolated from bovine cerebral cortex, a...

  3. Do the interfacial fluidities of cationic reverse micelles enhance with an increase in the water content?

    Science.gov (United States)

    Mali, K. S.; Dutt, G. B.

    2009-11-01

    The role of cosurfactant and water on the interfacial fluidities of reverse micelles formed with the cationic surfactant, cetyltrimethylammonium bromide (CTAB) has been examined by measuring the fluorescence anisotropies of two structurally similar ionic solutes, rhodamine 110 and fluorescein. For this purpose, reverse micellar systems with (CTAB/1-pentanol/cyclohexane/water) and without a cosurfactant (CTAB/chloroform-isooctane/water) have been chosen. In this study, the mole ratio of water to surfactant W has been varied in the region of 4-25. Experimental results indicate that the average reorientation time of the probe, which is a measure of the fluidity near the interfacial region, decreases by a factor of 1.5 and 1.4 for rhodamine 110 and fluorescein, respectively, as W goes up from 5 to 25 in CTAB/1-pentanol/cyclohexane/water reverse micellar system. In contrast, the average reorientation time, remains invariant for both the probe molecules in CTAB/chloroform-isooctane/water reverse micellar system despite an increase in W from 4 to 24. In case of CTAB/1-pentanol/cyclohexane/water reverse micellar system, the added water binds to bromide counter ions and also the hydroxyl groups of the cosurfactant, 1-pentanol, which results in an increase in the effective head group area. Such an increase in the effective head group area leads to a decrease in the packing parameter, and hence an increase in the interfacial fluidity. On the other hand, in CTAB/chloroform-isooctane/water system, the added water merely hydrates the bromide ions, thereby leaving the effective head group area unchanged. Thus, the interfacial fluidities remain invariant upon the addition of water in the absence of a cosurfactant.

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    María del Consuelo Figueroa-García

    Full Text Available 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.

  6. Working group report on simulation and in-situ observation of cement paste fluidity

    OpenAIRE

    Asakura, Etsuro; Tanaka, Hisanobu; Shimosaka, Kenichi; Tsukamoto, Katsuo; Komatsu, Ryuichi; Yoshizaki, Izumi; 朝倉 悦郎; 田中 久順; 下坂 建一; 塚本 勝男; 小松 隆一; 吉崎 泉

    2007-01-01

    We are studying the use of cement on the moon as a building material and the control of its properties, especially fluidity. The viscosity of cement paste in the space may be predicted by the general viscosity equation of Hattori and Izumi based on the DLVO (Derjaguin, Landau, Verway, Overbeek) theory that requires some parameters such as the particle friction coefficient, etc. In situ observation of dispersed particles in cement paste will be a key technology to clarify the mechanisms of the...

  7. Increased oxidative stress and decreased membrane fluidity in erythrocytes of CAD patients.

    Science.gov (United States)

    Pytel, Edyta; Olszewska-Banaszczyk, Małgorzata; Koter-Michalak, Maria; Broncel, Marlena

    2013-10-01

    One of many risk factors for cardiovascular disease appears to be oxidative stress. To estimate possible changes in redox balance, membrane fluidity, and cholesterol level in erythrocytes was collected erythrocytes from patients diagnosed with coronary artery disease (CAD). The study included 20 patients with previous myocardial infarction occurring more than 6 months prior to the time of screening with low-density lipoprotein cholesterol (LDL-C) > 70 mg/dL and 21 healthy controls. The following parameters were studied: catalase, glutathione peroxidase (GPx), superoxide dismutase (SOD), thiobarbituric acid reactive substrates (TBARS), sulfhydryl (SH) groups in membrane protein, total cholesterol level, and erythrocyte membrane fluidity. Our study showed an increase in the level of lipid peroxidation (13%) and total cholesterol (19%), and a decrease in membrane fluidity (14%) in the subsurface layers and in the deeper layers of erythrocyte membrane (7%) isolated from patients with CAD in comparison to healthy controls. A significant decrease in catalase (10%) and SOD (17%) activities were also observed. No changes in GPx activity or the level of SH groups were observed. Our study indicates that there are disorders in the antioxidant system as well as changes in the membrane structure of erythrocytes obtained from CAD patients.

  8. 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.

  9. Membrane fluidity of halophilic ectoine-secreting bacteria related to osmotic and thermal treatment.

    Science.gov (United States)

    Bergmann, Sven; David, Florian; Clark, Wiebke; Wittmann, Christoph; Krull, Rainer

    2013-12-01

    In response to sudden decrease in osmotic pressure, halophilic microorganisms secrete their accumulated osmolytes. This specific stress response, combined with physiochemical responses to the altered environment, influence the membrane properties and integrity of cells, with consequent effects on growth and yields in bioprocesses, such as bacterial milking. The aim of this study was to investigate changes in membrane fluidity and integrity induced by environmental stress in ectoine-secreting organisms. The halophilic ectoine-producing strains Alkalibacillus haloalkaliphilus and Chromohalobacter salexigens were treated hypo- and hyper-osmotically at several temperatures. The steady-state anisotropy of fluorescently labeled cells was measured, and membrane integrity assessed by flow cytometry and ectoine distribution. Strong osmotic downshocks slightly increased the fluidity of the bacterial membranes. As the temperature increased, the increasing membrane fluidity encouraged more ectoine release under the same osmotic shock conditions. On the other hand, combined shock treatments increased the number of disintegrated cells. From the ectoine release and membrane integrity measurements under coupled thermal and osmotic shock conditions, we could optimize the secretion conditions for both bacteria.

  10. 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.......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...... sensitizers from non-sensitizers. This study describes two of these assays, which when used in a tiered strategy, may be able to identify contact sensitizers and also to quantify sensitizer potency. Tier 1 is the human keratinocyte NCTC2544 IL-18 assay and tier 2 is the Epidermal Equivalent potency assay...

  11. Determining Regional Sensitivity to Energy-Related Water Withdrawals in Minnesota

    Science.gov (United States)

    McCulloch, A.; Brauman, K. A.

    2015-12-01

    Minnesota has abundant freshwater resources, yet concerns about water-impacts of energy and mining development are increasing. Statewide, total annual water withdrawals have increased, and, in some watersheds, withdrawals make up a large fraction of available water. The energy and mining sectors play a critical role in determining water availability, as water is used to irrigate biofuel feedstock crops, cool thermoelectric plants, and process and transport fuels and iron ore. We evaluated the Minnesota Department of Natural Resources (DNR) Water and Reporting System (MPARS) dataset (1988-2014) to identify regions where energy and mining-related water withdrawals are high or where they are increasing. The energy and mining sectors account for over 65 percent of total water extractions in Minnesota, but this percentage is greater in some regions. In certain southern and northeastern Minnesota watersheds, these extractions account for 90 percent of total water demand. Sensitivity to these demands is not dependent on total water demand alone, and is also not uniform among watersheds. We identified and evaluated factors influencing sensitivity, including population, extraction type (surface water or groundwater), percentage of increased demand, and whether withdrawals are consumptive or not. We determined that southern Minnesota is particularly sensitive to increased water demands, because of growing biofuel and sand extraction industries (the products of which are used in hydraulic fracturing). In the last ten years, ethanol production in Minnesota has increased by 440 percent, and over fifteen refineries (each with a capacity over 1.1 billion gallons), have been built. These users primarily extract from surface water bodies within a few watersheds, compromising local supplies. As these energy-related industries continue to grow, so will the demand for freshwater resources. Determining regional sensitivity to increased demands will allow policy-makers to manage the

  12. Electro chemical Aptasensor Based on Prussian Blue-Chitosan-Glutaraldehyde for the Sensitive Determination of Tetracycline

    Institute of Scientific and Technical Information of China (English)

    Guanghui Shen; Yemin Guo; Xia Sun∗; Xiangyou Wang

    2014-01-01

    In this paper, a novel and sensitive electrochemical aptasensor for detecting tetracycline (TET) with prussian blue (PB) as the label-free signal was fabricated. A PB-chitosan-glutaraldehyde (PB-CS-GA) system acting as the signal indicator was developed to improve the sensitivity of the electrochemical aptasensor. Firstly, the PB-CS-GA was fixed onto the glass carbon electrode surface. Then, colloidal gold nanoparticles (AuNPs) were droped onto the electrode to immobilize the anti-TET aptamer for preparation of the aptasensor. The stepwise assembly process of the aptasensor was characterized by cyclic voltammetry (C-V) and scanning electron microscope (SEM). The target TET captured onto the electrode induced the current response of the electrode due to the non-conducting biomoleculars. Under the optimum operating conditions, the response of differential pulse voltammetry (DPV) was used for detecting the concentration of TET. The proposed aptasensor showed a high sensitivity and a wide linear range of 10−9 ∼ 10−5 M and 10−5 ∼ 10−2 M with the correlation coefficients of 0.994 and 0.992, respectively. The detection limit was 3.2×10−10 M (RSD 4.12%). Due to its rapidity, sensitivity and low cost, the proposed aptasensor could be used as a pre-scanning method in TET determination for the analysis of livestock products.

  13. 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.

  14. 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.

  15. Highly sensitive electromembrane extraction for the determination of volatile organic compound metabolites in dried urine spot.

    Science.gov (United States)

    Suh, Joon Hyuk; Eom, Han Young; Kim, Unyong; Kim, Junghyun; Cho, Hyun-Deok; Kang, Wonjae; Kim, Da Som; Han, Sang Beom

    2015-10-16

    Electromembrane extraction coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for determination of ten volatile organic compound metabolites in dried urine spot samples. The dried urine spot approach is a convenient and economical sampling method, wherein urine is spotted onto a filter paper and dried. This method requires only a small amount of sample, but the analysis sometimes suffers from low sensitivity, which can lead to analytical problems in the detection of minor components in samples. The newly developed dried urine spot analysis using electromembrane extraction exhibited improved sensitivity and extraction, and enrichment of the sample was rapidly achieved in one step by applying an electric field. Aliquots of urine were spotted onto Bond Elut DMS cards and dried at room temperature. After drying, the punched out dried urine spot was eluted with water. Volatile organic compound metabolites were extracted from the sample through a supported liquid membrane into an alkaline acceptor solution inside the lumen of a hollow fiber with the help of an electric potential. The optimum extraction conditions were determined by using design of experiments (fractional factorial design and response surface methodology). Satisfactory sensitivity was achieved and the limits of quantification (LOQ) obtained were lower than the regulatory threshold limits. The method was validated by assessing the linearity, precision, accuracy, recovery, reproducibility, stability, and matrix effects. The results were acceptable, and the developed method was successfully applied to biological exposure monitoring of volatile organic compound metabolites in fifty human urine samples.

  16. Test of the notch technique for determining the radial sensitivity of the optical model potential

    CERN Document Server

    Yang, Lei; Jia, Hui-ming; Xu, Xin-Xing; Ma, Nan-Ru; Sun, Li-Jie; Yang, Feng; Zhang, Huan-Qiao; Li, Zu-Hua; Wang, Dong-Xi

    2015-01-01

    Detailed investigations on the notch technique are performed on the ideal data generated by the optical model potential parameters extracted from the 16O+208Pb system at the laboratory energy of 129.5 MeV, to study the sensitivities of this technique on the model parameters as well as the experimental data. It is found that, for the perturbation parameters, a sufficient large reduced fraction and an appropriate small perturbation width are necessary to determine the accurate radial sensitivity; while for the potential parameters, almost no dependence was observed. For the experimental measurements, the number of data points has little influence for the heavy target system, and the relative inner information of the nuclear potential can be derived when the measurement extended to a lower cross section.

  17. Determinants for patient satisfaction regarding aesthetic outcome and skin sensitivity after breast-conserving surgery.

    Science.gov (United States)

    Dahlbäck, Cecilia; Manjer, Jonas; Rehn, Martin; Ringberg, Anita

    2016-12-07

    With the development of new surgical techniques in breast cancer, such as oncoplastic breast surgery, increased knowledge of risk factors for poor satisfaction with conventional breast-conserving surgery (BCS) is needed in order to determine which patients to offer these techniques to. The aim of this study was to investigate patient satisfaction regarding aesthetic result and skin sensitivity in relation to patient, tumour, and treatment factors, in a consecutive sample of patients undergoing conventional BCS. Women eligible for BCS were recruited between February 1, 2008 and January 31, 2012 in a prospective setup. In all, 297 women completed a study-specific questionnaire 1 year after conventional BCS and radiotherapy. Potential risk factors for poor satisfaction were investigated using logistic regression analysis. The great majority of the women, 84%, were satisfied or very satisfied with the overall aesthetic result. The rate of satisfaction regarding symmetry between the breasts was 68% and for skin sensitivity in the operated breast it was 67%. Excision of more than 20% of the preoperative breast volume was associated with poor satisfaction regarding overall aesthetic outcome, as was axillary clearance. A high BMI (≥30 kg/m(2)) seemed to affect satisfaction with symmetry negatively. Factors associated with less satisfied patients regarding skin sensitivity in the operated breast were an excision of ≥20% of preoperative breast volume, a BMI of 25-30 kg/m(2), axillary clearance, and radiotherapy. Re-excision and postoperative infection were associated with lower rates of satisfaction regarding both overall aesthetic outcome and symmetry, as well as with skin sensitivity. Several factors affect patient satisfaction after BCS. A major determinant of poor satisfaction in this study was a large excision of breast volume. If the percentage of breast volume excised is estimated to exceed 20%, other techniques, such as oncoplastic breast surgery, with or

  18. A sensitive fluorimetric method for determination of trace amounts of nitrite based on luminescence energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lun, E-mail: wanglun@mail.ahnu.edu.c [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Chen Jingguo; Chen Hongqi; Zhou Cailing; Ling Bo; Fu Jie [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China)

    2011-01-15

    An efficient luminescence energy transfer (LET) system based on terbium(III)-sodium hexametaphosphate (Tb/SHMP) chelates as donor and 4-((4-(2-aminoethylamino)naphthalen-1-yl)diazenyl)benzenesulfonic acid dihydrochloride (ANDBS) as acceptor was developed for sensitive determination of trace nitrite. Stable and strong fluorescence Tb/SHMP chelates were prepared in aqueous solution. Based on Griess Reaction, ANDBS was generated by the quantitative reaction of nitrite, sulfanilamide and N-(1-naphtyl)-ethylenediamine dihydrochloride (N1NED). The degree of the overlap was effective for LET between the emission spectrum of Tb/SHMP chelates and the absorption spectrum of ANDBS. Based on the luminescence intensity quenching of Tb/SHMP chelates in proportion to the trace amounts of nitrite, a new assay for the selective and sensitive determination of nitrite was developed. Under the optimum conditions, the linear calibration graph was obtained with a linear range of 0.00040-0.20 {mu}g mL{sup -1} (R=0.99657). The detection limit of NO{sub 2}{sup -} was 0.00010 {mu}g mL{sup -1} (R=0.99657). The method was applied successfully to the determination of nitrite for synthetic samples.

  19. 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 accor

  20. 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

  1. New Spectrofluorimetric Method with Enhanced Sensitivity for Determination of Paroxetine in Dosage Forms and Plasma

    Directory of Open Access Journals (Sweden)

    Ibrahim A. Darwish

    2008-01-01

    Full Text Available New simple spectrofluorimetric method with enhanced sensitivity has been developed and validated for the determination of the antidepressant paroxetine (PXT in its dosage forms and plasma. The method was based on nucleophilic substitution reaction of PXT with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in an alkaline medium (pH 8 to form a highly fluorescent derivative that was measured at 545 nm after excitation at 490 nm. The factors affecting the reaction was carefully studied and optimized. The kinetics of the reaction was investigated, and the reaction mechanism was presented. Under the optimized conditions, linear relationship with good correlation coefficient (0.9993 was found between the fluorescence intensity and PXT concentration in the range of 80–800 ng ml−1. The limits of detection and quantitation for the method were 25 and 77 ng ml−1, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 3%. The proposed method was successfully applied to the determination of PXT in its pharmaceutical tablets with good accuracy; the recovery values were 100.2 ± 1.61%. The results obtained by the proposed method were comparable with those obtained by the official method. The proposed method is superior to the previously reported spectrofluorimetric method for determination of PXT in terms of its higher sensitivity and wider linear range. The high sensitivity of the method allowed its successful application to the analysis of PXT in spiked human plasma. The proposed method is practical and valuable for its routine application in quality control and clinical laboratories for analysis of PXT.

  2. 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.

  3. Studies on the fluidity of milk lipids of mothers from three socioeconomic groups of West Bengal, India.

    Science.gov (United States)

    Roy, Susmita; Ghosh, Santinath; Dhar, Pubali; Ghosh, Mahua

    2013-10-01

    This study evaluated the fluid character of human milk by determining the mean melting points (MMP) of fatty acids of milk lipid of Bengali mothers. Fatty acid methyl esters were analyzed by gas liquid chromatography. MMPs were calculated from the fatty acid concentration (% w/w) and their molar mass. Phospholipid content of samples was also determined. The MMPs of milk lipid of higher income group (n = 48), medium income group (n = 57) and lower income group (n = 112) mothers were found to be 31.33°C ± 0.61, 36.86°C ± 0.64 and 35.11°C ± 0.65, respectively, which showed a significant correlation with the fatty acid composition, with P milk lipid (34.43°C ± 0.63) of these three groups was below the core body temperature (37.4°C) of human beings, which perhaps helps in maintaining the milk fluidity as well as lipid digestion in breastfed infants.

  4. 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.)

  5. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stampfli, Nathalie C., E-mail: nathalie.stampfli@ufz.de [Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Quantitative Landscape Ecology, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau (Germany); Knillmann, Saskia; Liess, Matthias; Beketov, Mikhail A. [Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany)

    2011-07-15

    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 {mu}g/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 {mu}g/L. In contrast, in the series with relatively higher food availability and weak competition such effects were detected at 3 {mu}g/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.

  7. A sensitive spectrofluorimetric method for the determination of ranitidine hydrochloride in pharmaceutical preparation

    Science.gov (United States)

    Ulu, Sevgi Tatar; Çakar, Mahmut Bülent

    2012-08-01

    A simple, precise and sensitive spectrofluorimetric method was developed and validated for the determination of ranitidine in pharmaceutical preparations. The method is based on derivatization of ranitidine with 4-fluoro-7-nitrobenzofurazan (NBD-F). The method was successfully validated in accordance to ICH guidelines. The validation characteristics included linearity, limit of detection, limit of quantification, accuracy, precision, specificity and robustness. The method is linear over the range of 40-1200 ng/mL. The recoveries were ranged from 98.97 to 99.43%. The proposed method was applied for the determination of ranitidine in commercially available tablets. The results were compared with those obtained by reference method using t and F-tests.

  8. Cadmium telluride quantum dots as pH-sensitive probes for tiopronin determination

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yunqing; Ye Chao; Zhu Zhenghui [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China); Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Hu Yuzhu [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China) and Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China)], E-mail: njhuyuzu@126.com

    2008-03-03

    The pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) were used as proton probes for tiopronin determination. Based on the fluorescence quenching of CdTe QDs caused by tiopronin, a simple, rapid and specific quantitative method was proposed. Under the optimal conditions, the calibration plot of ln(F{sub 0}/F) with concentration of tiopronin was linear in the range of 0.15-20 {mu}g mL{sup -1}(0.92-122.5 {mu}mol L{sup -1}) with correlation coefficient of 0.998. The limit of detection (LOD) (3{sigma}/k) was 0.15 {mu}g mL{sup -1}(0.92 {mu}mol mL{sup -1}). The content of tiopronin in pharmaceutical tablet was determined by the proposed method and the result agreed with that obtained from the oxidation-reduction titration method and the claimed value.

  9. Terbium-sensitized luminescence optosensor for the determination of norfloxacin in biological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, E.J. Llorent [Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaen, Paraje Las Lagunillas, E-23071 Jaen (Spain); Reyes, J.F. Garcia [Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaen, Paraje Las Lagunillas, E-23071 Jaen (Spain); Barrales, P. Ortega [Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaen, Paraje Las Lagunillas, E-23071 Jaen (Spain); Diaz, A. Molina [Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaen, Paraje Las Lagunillas, E-23071 Jaen (Spain)]. E-mail: amolina@ujaen.es

    2005-03-14

    The use of a flow through solid phase terbium-sensitized luminescence system is described for the determination of the widely used fluoroquinolone norfloxacin. A chelate between the terbium ion and the analyte is formed online previously to the sample injection into the carrier stream. Then the chelate is transported towards the flow-through cell, where it is retained on a cationic Sephadex resin packed in the cell, developing the corresponding luminescence signal. Afterwards, an ethylenediaminetetraacetic acid solution was used as eluting agent, in order to regenerate the sensing zone. The system has been satisfactorily applied to the determination of norfloxacin in human urine and serum, without the need of a pre-treatment. The response was linear in the range 10-150 ng ml{sup -1}. The detection and quantification limits were 1.5 and 5 ng ml{sup -1}, respectively and the R.S.D. 1.82%.

  10. 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.

  11. Sensitive determination of bromazepam in human tissues using capillary gas chromatography-mass spectrometry.

    Science.gov (United States)

    Zhang, X X; Kudo, K; Imamura, T; Jitsufuchi, N; Nagata, T

    1996-02-23

    A reliable and sensitive gas chromatographic-mass spectrometric method was devised to determine the levels of bromazepam in human tissues. Bromazepam was extracted from body tissues using a three-step solvent extraction procedure. N-Desmethyldiazepam served as the internal standard. Selected ion monitoring with m/z 317 for bromazepam and m/z 270 for internal standard was used for quantitation. Calibration curves in all body tissues were linear over the concentration range from 50-500 ng/g. The lower detection limit in body tissues was 2-5 ng/g and the absolute recovery in body tissues was 27.8-68.0%. This method was used to determine the levels of bromazepam in tissues of an autopsied individual who had been prescribed psychotropic drugs and who was found dead in a car.

  12. Sensitive method of determination of gold (III using diacetyl monoxime isonicotinoyl hydrazone (DMIH

    Directory of Open Access Journals (Sweden)

    Gadikota Chandrasekhar Reddy

    2011-12-01

    Full Text Available Gold (III forms a yellow coloured water soluble complex with diacetyl monoxime isonicotinoyl hydrazone (DMIH reagent in acidic buffer pH 4.5 with ?max at 361 nm. The molar absorptivity and Sandell’s sensitivity are 1.50X10 4 L .mol -1.cm-1 and 0.00333 µg/cm2, respectively .The Beer’s law validity range is 0.985–11.82 µg/mL. The optimum concentration range is 1.97-9.85 µg/mL. Gold (III forms (M:L 1:1 complex with DMIH and stability constant of the complex is 3.263X106. The derivative spectrophotometric determination of Au (III was carried out by measuring peak height method. The developed derivative spectrophotometric method was employed for the determination of gold (III in synthetic alloy samples. The effect of various diverse ions was also studied.

  13. Protein amino acid composition of plasma membranes affects membrane fluidity and thereby ethanol tolerance in a self-flocculating fusant of Schizosaccharomyces pombe and Saccharomyces cerevisiae.

    Science.gov (United States)

    Hu, Chun-Keng; Bai, Feng-Wu; An, Li-Jia

    2005-09-01

    A combination of three amino acids including 1.0 g/L isoleucine, 0.5 g/L methionine and 2.0 g/L phenylalanine was found to enhance ethanol tolerance of a self-flocculating fusant of Schizosaccharomyces pombe and Saccharomyces cerevisiae. When subjected to 20% (V/V) ethanol for 9 h at 30 degrees C, all cells died whereas 57% remained viable for the cells grown in the presence of the three amino acids. Based on the analysis of protein amino acid composition of plasma membranes and the determination of plasma membrane fluidity by measuring fluorescence anisotropy using diphenylhexatriene as a probe, it was found that the significantly increased ethanol tolerance of cells grown with the three amino acids was due to the incorporation of the supplementary amino acids into the plasma membranes, thus resulting in enhanced ability of the plasma membranes to efficiently counteract the fluidizing effect of ethanol when subjected to ethanol stress. This is the first time to report that plasma membrane fluidity can be influenced by protein amino acid composition of plasma membranes.

  14. The effect of β-sitosterol on the properties of cholesterol/phosphatidylcholine/ganglioside monolayers--the impact of monolayer fluidity.

    Science.gov (United States)

    Hąc-Wydro, Katarzyna

    2013-10-01

    In this paper the influence of one of phytosterols, namely β-sitosterol on cholesterol (Chol)/phosphatidylcholine (PC)/ganglioside (GM3) monolayers was examined to find the correlation between the properties of model system and the effect of phytocompound. The studied monolayers differed in condensation and fluidity, which were modified by the structure of phosphatidylcholine. It was found that the incorporation of β-sitosterol into cholesterol/phosphatidylcholine/ganglioside films changes their morphology, condensation and interactions between the lipids. The substitution of cholesterol more strongly decreased the condensation and stability of the film containing PC molecules having monounsaturated chains than more densely packed monolayer composed of saturated phosphatidylcholine. However, thorough analysis of data obtained so far suggests that the magnitude of β-sitosterol effect is determined by the composition of the system rather than its fluidity itself. Moreover, the results collected herein correlate well with the findings that phytosterol more strongly inhibits the growth of cancer cells, which at a given proportion of cholesterol to phospholipids in membranes, have more unsaturated fatty acids within phospholipids molecules.

  15. Determination of atropine using Mn-doped ZnS quantum dots as novel luminescent sensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Azizi, Seyed Naser [Analytical Division, Faculty of Chemistry, University of Mazandaran, Babolsar 4741695447 (Iran, Islamic Republic of); Chaichi, Mohammad Javad, E-mail: jchaichi@yahoo.com [Analytical Division, Faculty of Chemistry, University of Mazandaran, Babolsar 4741695447 (Iran, Islamic Republic of); Shakeri, Parmis [Analytical Division, Faculty of Chemistry, University of Mazandaran, Babolsar 4741695447 (Iran, Islamic Republic of); Bekhradnia, Ahmadreza [Pharmaceutical Sciences Research Center, Department of Medicinal Chemistry, Mazandaran University of Medical Sciences, Sari (Iran, Islamic Republic of)

    2013-12-15

    A novel chemiluminescence (CL) method using water-soluble Mn-doped ZnS quantum dots (QDs) as sensitizers is proposed for the chemiluminometric determination of atropine in pharmaceutical formulation. Water-soluble Mn-doped ZnS QDs were synthesized by using L-cysteine 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 and photoluminescence (PL) emission spectroscopy. It was found that ZnS quantum dots acted as enhancers of the weak CL emission produced upon oxidation of sulfite by Ce(IV) in acidic medium. Trace amounts of atropine improved the sensitize effect of ZnS quantum dots yielding a significant chemiluminescence enhancement of the Ce(IV)–SO{sub 3}{sup 2−}–ZnS QD system. Therefore, a new CL analysis system was developed for the determination of atropine. Under the optimum conditions, there is a good linear relationship between the relative chemiluminescence intensity and the concentration of atropine in the range of 1×10{sup −9}–1×10{sup −6} M of atropine with a correlation coefficient (R{sup 2}) of 0.9992. The limit of detection of this system was found to be 2.54×10{sup −10} M. This method is not only simple, sensitive and low cost, but also reliable for practical applications. -- Highlights: • Mn-doped ZnS quantum dots could enhance the chemiluminescence (CL) of cerium(IV)–sodium sulfite system. • ZnS quantum dots were used as the nanocatalyst. • Trace amounts of atropine improved the sensitize effect of ZnS quantum dots. • This work is introduced as a new method for the determination of atropine commercial drugs. • Detection limit of atropine was obtained 2.54×10{sup −10} mol L{sup −1}.

  16. Eu(III)-Sensitized Luminescence Probe for Determination of Tolnaftate in Pharmaceuticals and Biological Fluids.

    Science.gov (United States)

    Alarfaj, Nawal A; El-Tohamy, Maha F

    2016-01-01

    A highly selective, sensitive, accurate, and reproducible luminescence procedure for determination of antifungal drug tolnaftate was developed. The introduced method was based on the formation of Europa Universalis III (Eu(III))-tolnaftate complex using sodium sulfite as a deoxygenated agent in the presence of acetate buffer (pH = 6) and micellar solution of anionic surfactant sodium dodecyl sulfate. The optimum conditions (effect of pH, buffer, surfactant, Eu(III), and sodium sulfite concentrations) for the luminescence signal were investigated and optimized. The luminescence signals were recorded at λex = 270 nm and λem = 460 nm. The method has a good linear response (0.2-130 μg/mL(-1)) between the luminescence intensity and the concentrations of the drug (r = 0.999), with a LOD 0.07 μg/mL(-1) and LOQ 0.2 μg/mL(-1). The luminescence signals of Eu (III)-tolnaftate-sodium dodecyl sulfate were found to be 200-fold more sensitive without the presence of micelle solution. The interferences of some additives, metals, amino acids, sugars, and other related pharmacological action drugs were examined and no interference was recorded. The proposed method was used for quick and simple determination of tolnaftate in its pharmaceuticals and biological fluids.

  17. Highly sensitive spectrofluorimetric method for determination of certain aminoglycosides in pharmaceutical formulations and human plasma.

    Science.gov (United States)

    Omar, Mahmoud A; Nagy, Dalia M; Hammad, Mohamed A; Aly, Alshymaa A

    2013-06-01

    A simple, reliable, highly sensitive and selective spectrofluorimetric method has been developed for determination of certain aminoglycosides namely amikacin sulfate, tobramycin, neomycin sulfate, gentamicin sulfate, kanamycin sulfate and streptomycin sulfate. The method is based on the formation of a charge transfer complexes between these drugs and safranin in buffer solution of pH 8. The formed complexes were quantitatively extracted with chloroform under the optimized experimental conditions. These complexes showed an excitation maxima at 519-524 nm and emission maxima at 545-570 nm. The calibration plots were constructed over the range of 4-60 pg mL(-1) for amikacin, 4-50 pg mL(-1) for gentamicin, neomycin and kanamycin, 4-40 pg mL(-1) for streptomycin and 5-50 pg mL(-1) for tobramycin. The proposed method was successfully applied to the analysis of the cited drugs in dosage forms. The proposed method was validated according to ICH and USP guidelines with respect to specificity, linearity, accuracy, precision and robustness. The high sensitivity of the proposed method allowed determination of amikacin and gentamicin in spiked and real human plasma.

  18. Determination of CO₂ sensitivity of micro-organisms in shaken bioreactors. II. Novel online monitoring method.

    Science.gov (United States)

    Amoabediny, Ghassem; Abbas, Mahdi Pesaran Haji; Büchs, Jochen

    2010-12-01

    In the present study, a new online monitoring method for the determination of the CO₂ sensitivity of micro-organisms, based on the values of the respiration factors [OTR (oxygen transfer rate) and CTR (carbon dioxide transfer rate)], obtained by using the RAMOS (respiratory activity monitoring system) device considering a variety of aeration rates in the measuring flask, is investigated. Based on the data of the OTR, obtained by RAMOS under a variety of specific aeration rates, the proposed new method was developed as an online monitoring method for CO₂ sensitivity of micro-organisms in shaken bioreactors. A maximum accumulated CO₂ concentration of 12% was derived in applied methods, provided that the cultivation system is carried out under optimal conditions. Additionally, to predict these conditions, an unsteady-state gas transfer model in shaken bioreactors would be very advantageous. The data of OTR obtained using the RAMOS device were analysed and recalculated by a programme considering the calibration factor (Cf). The major advantage of the new method is the possibility to determine the metabolic activity, regardless of manual sampling.

  19. Sensitive determination of carbendazim in orange juice by electrode modified with hybrid material.

    Science.gov (United States)

    Razzino, Claudia A; Sgobbi, Lívia F; Canevari, Thiago C; Cancino, Juliana; Machado, Sergio A S

    2015-03-01

    This paper describes the application of a glassy carbon electrode modified with a thin film of mesoporous silica/multiwalled carbon nanotubes for voltammetric determination of the fungicide carbendazim (CBZ). The hybrid material, (SiO2/MWCNT), was obtained by a sol-gel process using HF as the catalyst. The amperometric response to CBZ was measured at +0.73 V vs. Ag/AgCl by square wave voltammetry at pH 8.0. SiO2/MWCNT/GCE responded to CBZ in the linear range from 0.2 to 4.0 μmol L(-1). The calculated detection limit was 0.056 μmol L(-1), obtained using statistical methods. The SiO2/MWCNT/GCE sensor presented as the main characteristics high sensitivity, low detection limit and robustness, allowing CBZ determination in untreated real samples. In addition, this strategy afforded remarkable selectivity for CBZ against ascorbic and citric acid which are the main compounds of the orange juice. The excellent sensitivity and selectivity yielded feasible application for CBZ detection in orange juice sample.

  20. 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.

  1. Sensitive Determination of Sertraline in Commercial Drugs and Its Stability Check in Simulated Gastric Juice.

    Science.gov (United States)

    Koçoğlu, Elif Seda; Bakırdere, Sezgin; Keyf, Seyfullah

    2016-11-01

    A sensitive analytical method was developed for the determination of sertraline in commercial drug samples by using GC-MS. The selected-ion monitoring mode was used at the most sensitive m/z 274 to obtain a lower detection limit. LOD/LOQ values were obtained as 1.6/5.4 ng/mL for sertraline under the optimum conditions. The calibration plot was linear between 5.0 and 2000 ng/mL with the correlation coefficient of 0.9999. The validated method was successfully applied to three different brands of drug samples for both qualitative and quantitative measurement of sertraline. In this experiment, four replicate extractions were performed for each brand, and the results were compared to the values written on the labels of the drug brands. Spiking experiments were also performed to check the effect of the matrixes on the determination, and it was observed that there was no shift in the retention time of the analyte. In addition, simulated gastric juice experiments were performed to check the stability of sertraline in the stomach for 240 min, and it was observed that there was no change in the structure of the analyte.

  2. 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

    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......At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it should be very important, both from ethical and economic point of view, to discriminate allergy and irritation events, and to classify sensitizers according to their potency, without...... 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...

  3. 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

  4. The Effect of Lidocaine · HCl on the Fluidity of Native and Model Membrane Lipid Bilayers.

    Science.gov (United States)

    Park, Jun-Seop; Jung, Tae-Sang; Noh, Yang-Ho; Kim, Woo-Sung; Park, Won-Ick; Kim, Young-Soo; Chung, In-Kyo; Sohn, Uy Dong; Bae, Soo-Kyung; Bae, Moon-Kyoung; Jang, Hye-Ock; Yun, Il

    2012-12-01

    The purpose of this study is to investigated the mechanism of pharmacological action of local anesthetic and provide the basic information about the development of new effective local anesthetics. Fluorescent probe techniques were used to evaluate the effect of lidocaine·HCl on the physical properties (transbilayer asymmetric lateral and rotational mobility, annular lipid fluidity and protein distribution) of synaptosomal plasma membrane vesicles (SPMV) isolated from bovine cerebral cortex, and liposomes of total lipids (SPMVTL) and phospholipids (SPMVPL) extracted from the SPMV. An experimental procedure was used based on selective quenching of 1,3-di(1-pyrenyl)propane (Py-3-Py) and 1,6-diphenyl-1,3,5-hexatriene (DPH) by trinitrophenyl groups, and radiationless energy transfer from the tryptophans of membrane proteins to Py-3-Py. Lidocaine·HCl increased the bulk lateral and rotational mobility of neuronal and model membrane lipid bilayes, and had a greater fluidizing effect on the inner monolayer than the outer monolayer. Lidocaine·HCl increased annular lipid fluidity in SPMV lipid bilayers. It also caused membrane proteins to cluster. The most important finding of this study is that there is far greater increase in annular lipid fluidity than that in lateral and rotational mobilities by lidocaine·HCl. Lidocaine·HCl alters the stereo or dynamics of the proteins in the lipid bilayers by combining with lipids, especially with the annular lipids. In conclusion, the present data suggest that lidocaine, in addition to its direct interaction with proteins, concurrently interacts with membrane lipids, fluidizing the membrane, and thus inducing conformational changes of proteins known to be intimately associated with membrane lipid.

  5. A sensitive post-column photochemical derivatization/fluorimetric detection system for HPLC determination of bisphosphonates.

    Science.gov (United States)

    Pérez-Ruiz, Tomás; Martínez-Lozano, Carmen; García-Martínez, María Dolores

    2009-02-27

    A new reversed-phase ion-pair high-performance liquid chromatographic (HPLC) method has been developed for the determination of the following bisphosphonic acids: alendronic acid (ALEN), etidronic acid (ETID), ibandronic acid (IBAN) and risedronic acid (RISE). Separation was achieved on a C(18) column using a mixture of 50 mmol L(-1) borate buffer pH 9.0 containing 0.25 mmol L(-1) tetrabutylammonium chloride and 0.5 mmol L(-1) EDTA and acetonitrile (97:3) as the mobile phase. The sensitive detection of the above bisphosphonic acids was based on their oxidation to orthophosphate by the on-line peroxydisulfate-assisted photolysis followed by post-column reaction with molybdate to yield phosphomolybdate. This subsequently reacted with thiamine to generate thiochrome and, finally, the fluorescence of thiochrome was measured at 440 nm with excitation at 375 nm. The developed method is precise with a mean relative standard deviation of 1.3%, sensitive (with a detection limit at the nmol L(-1) level), accurate, specific, rapid (analysis time approximately 13 min) and inexpensive because to the low cost of the reagents. The assay was applied to the analysis of the four bisphosphonic acids in commercial dosage formulations, in which the excipients did not interfere with the determination. The method was also applied to the determination of etidronate, risedronate and ibandronate in human urine. Sample preparation involves precipitation of the analytes from urine along with endogenous phosphates such as calcium salts by addition of calcium chloride at alkaline pH and dissolution of the precipitate in 0.05 mol L(-1) ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid.

  6. Determination of flavonoids in pharmaceutical preparations using Terbium sensitized fluorescence method

    Directory of Open Access Journals (Sweden)

    M Shaghaghi

    2009-12-01

    Full Text Available "nBackground and the Purpose of the Study: The aim of this study was development and validation of a simple, rapid and sensitive spectrofluorimetric method for determination of total flavonoids in two topical formulations of Calendula officinalis, Ziziphus Spina-christi and an oral drop of Hypiran perforatum L. The proposed method is based on the formation of terbium (Tb3+ "n-flavonoids (quercetin as a reference standard complex at pH 7.0, which has fluorescence intensely with maximum emission at 545 nm when excited at 310 nm. "nMethod "n: For ointments masses of topical formulations were weighed and added to ethanol-aqueous buffer (pH 10.0 and the resulting mixtures were shaken and then two phases were separated by centrifugation. Aqueous phases were filtered and then diluted with water. For Hypiran drops an appropriate portion was diluted with ethanol and then aliquots of sample or standard solutions were determined according to the experimental procedure. "nResults "n: Under the optimum conditions, total concentrations of flavonoids (as quercetin equivalent in three tested formulations were found to be 0.204 mg/g (for Dermatin cream, 0.476 mg/g (for Calendula ointment and 13.50 μg/ml (for Hypiran drops. Analytical recoveries from samples spiked with different amounts of quercetin were 96.1-104.0 % with RSD % of less than 3.5. Conclusion : The proposed method which requires a simple dissolution step without any matrix interferences provided high sensitivity and selectivity and was easily applied to determine total flavonoids in real samples of three investigated formulations with excellent reproducibility.

  7. On the fluidity of consonance and dissonance: The influence of musical context

    OpenAIRE

    Arthurs, Y.; Timmers, R.

    2016-01-01

    The consonance/dissonance (C/D) level of a triadic chord is not a fixed or absolute value. Rather, it is fluid, since C/D depends both on a chord’s sonic characteristics and on the musical context in which it appears. To test the fluidity of C/D—the extent to which C/D perception is dependent on musical context—4 types of chords (major, minor, augmented, and diminished triads) were presented in isolation (“without musical context”) and as part of a short cadence (IV-V-I, “with musical context...

  8. Effect of Morinda citrifolia fruit extract and its iridoid glycosides on blood fluidity.

    Science.gov (United States)

    Murata, Kazuya; Abe, Yumi; Futamura-Masuda, Megumi; Uwaya, Akemi; Isami, Fumiyuki; Deng, Shixin; Matsuda, Hideaki

    2014-07-01

    The aim of this study was to investigate the effect of Morinda citrifolia fruit on blood fluidity. M. citrifolia fruit extract (MCF-ext) was investigated for its influence on blood aggregation and fibrinolysis. MCF-ext inhibited polybrene-induced erythrocyte aggregation and thrombin activity. The fibrinolytic activity of MCF-ext, in the euglobulin lysis time test and fibrin plate assay, is reported here for the first time. One of the active compounds was an iridoid glycoside, asperulosidic acid. The results indicated that MCF-ext is a potentially useful health food which is capable of improving blood flow and preventing lifestyle-related diseases.

  9. EFFECTS OF QUERCETIN ON MEMBRANE FLUIDITY OF INJURED VASCULAR ENDOTHELIAL CELLS WITH HYPOXIA AND THE LACK OF GLUCOSE

    Institute of Scientific and Technical Information of China (English)

    林蓉; 刘俊田; 甘伟杰

    2003-01-01

    Objective To study the effects of different concentrations of Quercetin on nitric oxide (NO) production and membrane fluidity of the injured human umbilical vein vascular endothelial cell line(ECV-304) with hypoxia and the lack of glucose. Methods The experiments were performed in the culture of ECV-304 injured with hypoxia and the lack of glucose in vitro. The releases of intracellular lactate dehydrogenase(LDH) of ECV-304 was measured with automatic biochemistry analysis. NO level of ECV-304 was monitored with colorimetry. The membrane fluidity of ECV-304 was measured with the fluorescence polarization method. Results After ECV-304 was cultured in hypoxia and the the lack of glucose for 24 hours, the release of LDH and the membrane fluidity were increased significantly; NO level was decreased. Preincubation of ECV-304 with 20, 80,160μmol*L-1 of Quercetin for 24 hours reduced LDH activity, membrane fluidity and increased the level of NO in hypoxia and the lack of glucose induced ECV-304. Conclusion These results demonstrate that Quercetin can produce the protective effect on hypoxia and the lack of glucose induced injury of ECV-304 by increasing release of NO and changing membrane fluidity.

  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. A kinetic clutch governs religation by type IB topoisomerases and determines camptothecin sensitivity.

    Science.gov (United States)

    Seol, Yeonee; Zhang, Hongliang; Pommier, Yves; Neuman, Keir C

    2012-10-02

    Type IB topoisomerases (Top1Bs) relax excessive DNA supercoiling associated with replication and transcription by catalyzing a transient nick in one strand to permit controlled rotation of the DNA about the intact strand. The natural compound camptothecin (CPT) and the cancer chemotherapeutics derived from it, irinotecan and topotecan, are highly specific inhibitors of human nuclear Top1B (nTop1). Previous work on vaccinia Top1B led to an elegant model that describes a straightforward dependence of rotation and religation on the torque caused by supercoiling. Here, we used a single-molecule DNA supercoil relaxation assay to measure the torque dependence of nTop1 and its inhibition by CPT. For comparison, we also examined mitochondrial Top1B and an N-terminal deletion mutant of nTop1. Despite substantial sequence homology in their core domains, nTop1 and mitochondrial Top1B exhibit dramatic differences in sensitivity to torque and CPT, with the N-terminal deletion mutant of nTop1 showing intermediate characteristics. In particular, nTop1 displays nearly torque-independent religation probability, distinguishing it from other Top1B enzymes studied to date. Kinetic modeling reveals a hitherto unobserved torque-independent transition linking the DNA rotation and religation phases of the enzymatic cycle. The parameters of this transition determine the torque sensitivity of religation and the efficiency of CPT binding. This "kinetic clutch" mechanism explains the molecular basis of CPT sensitivity and more generally provides a framework with which to interpret Top1B activity and inhibition.

  12. Progression of glomerular filtration rate reduction determined in conscious Dahl salt-sensitive hypertensive rats.

    Science.gov (United States)

    Cowley, Allen W; Ryan, Robert P; Kurth, Terry; Skelton, Meredith M; Schock-Kusch, Daniel; Gretz, Norbert

    2013-07-01

    Sequential changes in glomerular filtration rate during development of hypertension in the conscious Dahl salt-sensitive rats were determined using a new method for measurement. Using a miniaturized device, disappearance curves of fluorescein isothiocyanate-sinistrin were measured by transcutaneous excitation and real-time detection of the emitted light through the skin. Rats with implanted femoral venous catheters (dye injection and sampling) and carotid catheters (mean arterial pressure by telemetry) were studied, while maintained on a 0.4% NaCl diet and on days 2, 5, 7, 14, and 21 after switching to 4.0% (high-salt [HS]) diet. A separate group of rats were maintained on 0.4% for 21 days as a time control. Mean arterial pressure rose progressively from the last day of 0.4% (130±2 mm Hg) reaching significance by day 5 of HS and averaged 162±7 mm Hg by day 21. Urine albumin excretion was significantly elevated (×3) by day 7 of HS in Dahl salt-sensitive rats. Glomerular filtration rate reduced on day 14 of HS falling from 1.53±0.06 mL/min per 100 g body weight to 1.27±0.04. By day 21, glomerular filtration rate had fallen 28% to 1.1±0.04 mL/min per 100 g (t(1/2) 28.4±1.1 minute.) No significant reductions of creatinine clearance were observed throughout the study in response to HS demonstrating the insensitivity of creatinine clearance measurements even with creatinine measured using mass spectrometry. We conclude that the observed reduction of glomerular filtration rate was a consequence and not a cause of the hypertension and that this noninvasive approach could be used in these conscious Dahl salt-sensitive rats for a longitudinal assessment of renal function.

  13. A Sensitive Competitive ELISA for Determination of Biotin in Transformed Yeast Culture Media

    Institute of Scientific and Technical Information of China (English)

    YANGHong

    2003-01-01

    Aim To develop a sensitive competitive ELISA for the determination of biotin in transformed yeast culture media.Methods The ELISA plate was firstly coated with Mycoplasma hyopneumoniae, and then successively incubated with rabbit ami-Mycoplasma hyopneumoniae serum and goat anti-rabbit IgG-biotin to form the solid biotin, which competed with the biotin in the solution (standard or sample) for the limited streptavidin-horse radish peroxidase conjugate. The standard calibration curve for biotin analysis was constructed in the range of 50-2000ng·L-1. Results The detection limit for biotin was found to be 83 ng·L-1 , which waa about 1000 times lower than the lowest determination concenlration in the reported ELISA for biotin analysis. The relative standard deviations for the spiked samples at biotin concerarations of 200 ng·L-1, 500 ng·L-1 , and 1000 ng·L-1 were 24.87%, 6.15%, and 7.86%, respectively, with the average recovery of 101.13%. The wild yeast and its sixty-three transformed yeast culture media were applied to the developed ELISA for the determination of biotin. It was found that the biotin concentrations in more than 85 % of the tested samples were enhanced with different increase factors after transformation. Conclusion Utilization of Mycoplasma hyopnetunoniae as the coating protein improves the precision and accmacy oftbe ELISA assay, which might be used for the biotin assay in other media.

  14. Determination of ranitidine, nizatidine, and cimetidine by a sensitive fluorescent probe.

    Science.gov (United States)

    Chang, Yin-Xia; Qiu, Yue-Qin; Du, Li-Ming; Li, Chang-Feng; Guo, Min

    2011-10-21

    A validated, simple, and sensitive fluorescence quenching method for the determination of ranitidine, nizatidine, and cimetidine in tablets and biological fluids is presented. This is the first single fluorescence method reported for the analysis of all three H(2) antagonists. The competitive reaction between the investigated drug and the palmatine probe for the occupancy of the cucurbit[7]uril (CB[7]) cavity was studied using spectrofluorometry. CB[7] was found to react with the probe to form a stable complex. The fluorescence intensity of the complex was also enhanced greatly. However, the addition of the drug dramatically quenched the fluorescence intensity of the complex. Accordingly, a new fluorescence quenching method for the determination of the studied drugs was established. The different experimental parameters affecting the fluorescence quenching intensity were studied carefully. At optimum reaction conditions, the rectilinear calibration graphs between the fluorescence quenching values (ΔF) and the medicament concentration were obtained in the concentration range of 0.04-1.9 μg mL(-1) for the investigated drugs. The limits of detection ranged from 0.013 to 0.030 μg mL(-1) at 495 nm using an excitation wavelength of 343 nm. The proposed method can be used for the determination of the three H(2) antagonists in raw materials, dosage forms and biological fluids.

  15. Baroreflex sensitivity as a determinant of responses to hydralazine in dogs.

    Science.gov (United States)

    Vidrio, H

    1983-01-01

    In order to evaluate the relation between hypotension induced by hydralazine and the resultant reflex tachycardia, as well as the role of baroreflex sensitivity in determining the magnitude of these responses, the drug was administered orally at a dose of 1 mg/kg to a group of trained conscious normotensive and renal hypertensive dogs. Responses were assessed by measuring blood pressure and heart rate for 8 hr after dosing and integrating the changes observed over time in order to obtain a mean value. Baroreflex gain was calculated as the ratio of heart rate to blood pressure responses. Hypotension was greater in hypertensives, whereas tachycardia was not different between groups. Gain was therefore smaller in hypertensives, but not uniformly so, a portion of these animals having values within the normotensive range. This high gain group responded with less hypotension and more tachycardia than did the low gain group. Differences in pressure and rate responses to repeated administration of hydralazine between the two groups were minimal. It is suggested that baroreflex gain, an innate individual characteristic, is an important determinant of acute pressure responses to hydralazine in dogs, hypertensive animals having less gain than normotensives and showing increased hypotensive responses. Gain appears not to be as important in determining the chronic effects of the drug.

  16. Determination of the biotin content of select foods using accurate and sensitive HPLC/avidin binding.

    Science.gov (United States)

    Staggs, C G; Sealey, W M; McCabe, B J; Teague, A M; Mock, D M

    2004-12-01

    Assessing dietary biotin content, biotin bioavailability, and resulting biotin status are crucial in determining whether biotin deficiency is teratogenic in humans. Accuracy in estimating dietary biotin is limited both by data gaps in food composition tables and by inaccuracies in published data. The present study applied sensitive and specific analytical techniques to determine values for biotin content in a select group of foods. Total biotin content of 87 foods was determined using acid hydrolysis and the HPLC/avidin-binding assay. These values are consistent with published values in that meat, fish, poultry, egg, dairy, and some vegetables are relatively rich sources of biotin. However, these biotin values disagreed substantially with published values for many foods. Assay values varied between 247 times greater than published values for a given food to as much as 36% less than the published biotin value. Among 51 foods assayed for which published values were available, only seven agreed within analytical variability (720%). We conclude that published values for biotin content of foods are likely to be inaccurate.

  17. A novel polymer inclusion membranes based optode for sensitive determination of Al3+ ions

    Science.gov (United States)

    Suah, Faiz Bukhari Mohd; Ahmad, Musa; Heng, Lee Yook

    2015-06-01

    A novel approach for the determination of Al3+ from aqueous samples was developed using an optode membrane produced by physical inclusion of Al3+ selective reagent, which is morin into a plasticized poly(vinyl chloride). The inclusion of Triton X-100 was found to be valuable and useful for enhancing the sorption of Al3+ ions from liquid phase into the membrane phase, thus increasing the intensity of optode's absorption. The optode showed a linear increase in the absorbance at λmax = 425 nm over the concentration range of 1.85 × 10-6-1.1 × 10-4 mol L-1 (0.05-3 μg mL-1) of Al3+ ions in aqueous solution after 5 min. The limit of detection was determined to be 1.04 × 10-6 mol L-1 (0.028 μg mL-1). The optode developed in the present work was easily prepared and found to be stable, has good mechanical strength, sensitive and reusable. In addition, the optode was tested for Al3+ determination in lake water, river water and pharmaceutical samples, which the result was satisfactory.

  18. 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.

  19. 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.

  20. Spectrophotometric and high performance liquid chromatographic methods for sensitive determination of bisphenol A.

    Science.gov (United States)

    Zhuang, Yafeng; Zhou, Meng; Gu, Jia; Li, Xiangmei

    2014-03-25

    A new spectrophotometric method for the determination of trace amounts of bisphenol A based on a diazotization-coupling reaction was developed. In acidic solution, clenbuterol was first diazotized with sodium nitrite, then coupled with bisphenol A to from an azo-compound [I] in NH3-NH4Cl buffer, which shows a maximum absorption at 410 nm. The effects of the amount of sodium nitrite, diazo reaction time, the amount of clenbuterol, coupling reaction time and coupling reaction temperature have been examined. Under the optional conditions, the determination of the linear range of bisphenol A is 0.24-8.4 μg/mL, correlation coefficient is 0.9905 and detection limit of this method is 0.15 μg/mL. The spectrophotometric method is simple, rapid, high sensitivity with better accuracy. High performance liquid chromatography (HPLC) technique combined with this new spectrophotometric method has been also developed for the measurement of bisphenol A. The analysis was achieved on a C18 column using water and methanol as a mobile phase and the detection was done spectrophotometrically at 410 nm. These reported methods were applied to the determination of bisphenol A in hot water in contact with commercially available table-water bottle samples.

  1. 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).

  2. 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.

  3. Registered report: androgen receptor splice variants determine taxane sensitivity in prostate cancer

    Directory of Open Access Journals (Sweden)

    Xiaochuan Shan

    2015-09-01

    Full Text Available The Prostate Cancer Foundation-Movember Foundation Reproducibility Initiative seeks to address growing concerns about reproducibility in scientific research by conducting replications of recent papers in the field of prostate cancer. This Registered Report describes the proposed replication plan of key experiments from “Androgen Receptor Splice Variants Determine Taxane Sensitivity in Prostate Cancer” by Thadani-Mulero and colleagues (2014 published in Cancer Research in 2014. The experiment that will be replicated is reported in Fig. 6A. Thadani-Mulero and colleagues generated xenografts from two prostate cancer cell lines; LuCaP 86.2, which expresses predominantly the ARv567 splice variant of the androgen receptor (AR, and LuCaP 23.1, which expresses the full length AR as well as the ARv7 variant. Treatment of the tumors with the taxane docetaxel showed that the drug inhibited tumor growth of the LuCaP 86.2 cells but not of the LuCaP 23.1 cells, indicating that expression of splice variants of the AR can affect sensitivity to docetaxel. The Prostate Cancer Foundation-Movember Foundation Reproducibility Initiative is a collaboration between the Prostate Cancer Foundation, the Movember Foundation and Science Exchange, and the results of the replications will be published by PeerJ.

  4. Selective and sensitive determination of dopamine by composites of polypyrrole and graphene modified electrodes.

    Science.gov (United States)

    Si, Peng; Chen, Hailan; Kannan, Palanisamy; Kim, Dong-Hwan

    2011-12-21

    A novel method is developed to fabricate the polypyrrole (PPy) and graphene thin films on electrodes by electrochemical polymerization of pyrrole with graphene oxide (GO) as a dopant, followed by electrochemical reduction of GO in the composite film. The composite of PPy and electrochemically reduced graphene oxide (eRGO)-modified electrode is highly sensitive and selective toward the detection of dopamine (DA) in the presence of high concentrations of ascorbic acid (AA) and uric acid (UA). The sensing performance of the PPy/eRGO-modified electrode is investigated by differential pulse voltammetry (DPV), revealing a linear range of 0.1-150 μM with a detection limit of 23 nM (S/N = 3). The practical application of the PPy/eRGO-modified electrode is successfully demonstrated for DA determination in human blood serum.

  5. Determination of the actuator sensitivity of electromechanical polypropylene films by atomic force microscopy

    Science.gov (United States)

    Peltonen, Jouko; Paajanen, Mika; Lekkala, Jukka

    2000-10-01

    The actuator functionality of electromechanical polypropylene films was studied using atomic force microscopy. The film carries a permanent electric charge and includes microbubbles as a result of two-dimensional stretching of the film. The thickness change of various film structures covered with electrodes was measured as a function of external voltage. The dependence was found to be nonlinear, the thickness change in the range 0.001%-0.1% of the total film thickness and affected by the internal charge density of the film. Applying a capacitor model including an air gap within the polymer layer enabled the determination of the Young's modulus, the interfacial charge density and the actuator sensitivity of the studied structures.

  6. Determination and sensitivity analysis of the seismic velocity of a shallow layer from refraction traveltimes measures

    Directory of Open Access Journals (Sweden)

    S Zein

    2016-03-01

    Full Text Available In this paper, we are interested in determining the seismic velocity of ashallow under-ground layer from refraction traveltimes measures. Wepresent a study case taken from an experimental seismic survey. The studycase is a wide-angle seismic inversion using experimental traveltimesmeasures and based on ray tracing technique and genetic algorithms. Thehypothesis on the velocity distribution, coming from the seismicexperiment, makes the computation of some seismic rays expensive intime. We propose to reduce the computations time by introducing aformulation of the inverse problem that avoids such costly rays, hence theinversion becomes feasible.Also we present a sensitivity analysis based on a singular valuedecomposition of the jacobian of the traveltimes with respect to velocity.We give the relationship between the traveltimes measure errors and thevelocity estimation error. We discuss the advantages of this method overthe classical one based on the resolution matrix.

  7. Magnetoresistive polyaniline-silicon carbide metacomposites: plasma frequency determination and high magnetic field sensitivity.

    Science.gov (United States)

    Gu, Hongbo; Guo, Jiang; Khan, Mojammel Alam; Young, David P; Shen, T D; Wei, Suying; Guo, Zhanhu

    2016-07-20

    The Drude model modified by Debye relaxation time was introduced to determine the plasma frequency (ωp) in the surface initiated polymerization (SIP) synthesized β-silicon carbide (β-SiC)/polyaniline (PANI) metacomposites. The calculated plasma frequency for these metacomposites with different loadings of β-SiC nanoparticles was ranging from 6.11 × 10(4) to 1.53 × 10(5) rad s(-1). The relationship between the negative permittivity and plasma frequency indicates the existence of switching frequency, at which the permittivity was changed from negative to positive. More interestingly, the synthesized non-magnetic metacomposites, observed to follow the 3-dimensional (3-D) Mott variable range hopping (VRH) electrical conduction mechanism, demonstrated high positive magnetoresistance (MR) values of up to 57.48% and high MR sensitivity at low magnetic field regimes.

  8. 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.

  9. High-performance liquid chromatographic determination of vertilmicin in rat plasma using sensitive fluorometric derivatization.

    Science.gov (United States)

    Liu, Zhen; Sha, Yunfei; Huang, Taomin; Yang, Bei; Duan, Geng-Li

    2005-12-15

    A sensitive and reliable high-performance liquid chromatographic method was developed for the determination of vertilmicin in rat plasma. Derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by C(18) reversed-phase chromatography allowed the fluorimetric detection of vertilmicin. Optimal conditions for the derivatization of vertilmicin are described. The limit of quantification was 0.02 mg/L. The pharmacokinetics of vertilmicin was studied in 24 rats following intramuscular injection (i.m.) of different doses (4, 8, 16, 32 mg/kg of body weight). The pharmacokinetic parameter values were estimated by use of 3P97 program. In this study, we assessed the dose proportionality of vertilmicin after single intramuscular injection doses and obtained new information on the pharmacokinetics of the compound.

  10. Highly sensitive and selective spectrophotometric and spectrofluorimetric methods for the determination of ropinirole hydrochloride in tablets

    Science.gov (United States)

    Aydoğmuş, Zeynep

    2008-06-01

    Three sensitive, selective, accurate spectrophotometric and spectrofluorimetric methods have been developed for the determination of ropinirole hydrochloride in tablets. The first method was based on measuring the absorbance of drug solution in methanol at 250 nm. The Beer's law was obeyed in the concentration range 2.5-24 μg ml -1. The second method was based on the charge transfer reaction of drug, as n-electron donor with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as π-acceptor in acetonitrile to give radical anions that are measured at 842 nm. The Beer's law was obeyed in the concentration range 0.6-8 μg ml -1. The third method was based on derivatization reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 8.5 followed by measuring the fluorescence intensity at 525 nm with excitation at 464 nm in chloroform. Beer's law was obeyed in the concentration range 0.01-1.3 μg ml -1. The derivatization reaction product of drug with NBD-Cl was characterized by IR, 1H NMR and mass spectroscopy. The developed methods were validated. The following analytical parameters were investigated: the molar absorptivity ( ɛ), limit of detection (LOD, μg ml -1) and limit of quantitation (LOQ, μg ml -1), precision, accuracy, recovery, and Sandell's sensitivity. Selectivity was validated by subjecting stock solution of ropinirole to acidic, basic, oxidative, and thermal degradation. No interference was observed from common excipients present in formulations. The proposed methods were successfully applied for determination of drug in tablets. The results of these proposed methods were compared with each other statistically.

  11. A rapid method for determining salinomycin and monensin sensitivity in Eimeria tenella.

    Science.gov (United States)

    Jenkins, M C; O'Brien, C N; Fuller, L; Mathis, G F; Fetterer, R

    2014-12-15

    Standard methods of determining the ionophore sensitivity of Eimeria rely on infecting chickens with an isolate or a mixture of Eimeria spp. oocysts in the presence of different anti-coccidial drugs. The purpose of this study was to develop a rapid in vitro method for assessing salinomycin and monensin sensitivity in Eimeria tenella. Cultures of MDBK cells were grown to 85% confluency, and then inoculated with excysted E. tenella laboratory strain (APU-1) sporozoites in the presence of different concentrations of salinomycin or monensin. At various timepoints, the monolayers were fixed for counting intraceullar sporozoites, or were subjected to DNA extraction, followed by molecular analysis using quantitative (qPCR) or semi-quantitative PCR (sqPCR). Preliminary experiments showed that 24h was the optimum time for harvesting the E. tenella-infected cell cultures. The average number of E. tenella sporozoites relative to untreated controls displayed a linear decrease between 0.3 and 33.0 μg/ml salinomycin and between 0.3 and 3.3 μg/ml monensin. A similar pattern was observed in the relative amount of E. tenella DNA as measured by sqPCR. A linear decrease in the relative amount of E. tenella DNA was observed over the entire range of salinomycin and monensin concentrations as measured by qPCR possibly reflecting the greater sensitivity of this assay. Comparison of sporozoite counting, sqPCR, and qPCR signals using a criterion of 50% inhibition in sporozoite numbers or level of PCR amplification product showed good agreement between the three assays. E. tenella field isolates (FS-1 and FS-2) displaying resistance to salinomycin and monensin were evaluated in the in vitro assay using qPCR and sqPCR. Compared to E. tenella APU-1, the E. tenella FS-1 and FS-2 isolates showed higher levels of E. tenella DNA at 24h by both qPCR and sqPCR. This in vitro assay represents a significant advance in developing rapid, cost-effective methods for assessing ionophore sensitivity in E

  12. The powers of water-user associations: on multiplicity, fluidity, and durability in the Peruvian Andes

    Directory of Open Access Journals (Sweden)

    Andres Verzijl

    2015-03-01

    Full Text Available In this article we use insights from institutional bricolage and actor network theory to make sense of an Andean water user association (WUA and its bricoleurs in the Region of Ayacucho, Peru. Rather than being designed and clearly defined, we see natural resource institutions as continuously performed and patched together, through heterogeneous elements and practices, by those that live, experience and enact these institutions every day and by those who make sense of them. We present three cases, three supra-community efforts to secure water livelihoods, in which the Ayacucho water user association is enacted differently. Similar actors and practices like, water law, local customs, water bodies, and ecological services are performed in alternate ways for diverse purposes. It is this range of co-existing performances or enactments and the fluidity of actors and bricoleurs which enables an institution to adapt and adjust. We hold that an Andean WUA can be a bureaucratic imposition, but in many ways the WUA is something else too: a strategic ally; a prerequisite for subsidy consideration, a marketplace for exchanging goods and services and more. In the setting of the contemporary Peruvian Andes, the durability of natural resource institutions can be understood through the fluidity and multiplicity of performances and purposes. This has normative and political implications for researchers and policymakers as to what enactment they consider and target.

  13. Highly sensitive ion pair liquid chromatographic determination of albendazole marker residue in animal tissues.

    Science.gov (United States)

    Fletouris, Dimitrios J; Papapanagiotou, Elias P; Nakos, Dimitrios S; Psomas, Ioannis E

    2005-02-23

    A simple, rapid, and highly sensitive ion pair liquid chromatographic method for the determination of albendazole sulfoxide, albendazole 2-aminosulfone, and albendazole sulfone, which constitute the marker residue of albendazole in animal tissues (muscle, fat, liver, and kidney), is described. Tissue samples were extracted with acetonitrile, and the extracts were partitioned, as ion pairs, into dichloromethane. The organic layer was evaporated to dryness, and the residue was reconstituted in phosphate buffer and extracted with ethyl acetate. Separation was carried out isocratically with a mobile phase containing both positively and negatively charged pairing ions. Detection was performed fluorometrically, with excitation and emission wavelengths set at 290 and 320 nm, respectively. Overall recoveries were better than 76%, and the overall relative standard deviation was better than 7.3% in all tissues examined. The limits of quantification were 20, 1, and 0.5 ng/g for sulfoxide, 2-aminosulfone, and sulfone metabolites, respectively. The method was successfully applied to determine residues in tissues of two sheep orally administered an albendazole formulation.

  14. 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.

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

    Science.gov (United States)

    Thapliyal, Neeta Bachheti; Chiwunze, Tirivashe Elton; Karpoormath, Rajshekhar; 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 0.01-1μM and 0.001-1μM with a detection limit of 3.5nM and 0.9nM 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. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Ultra-sensitive Flow Injection Analysis (FIA) determination of calcium in ice cores at ppt level.

    Science.gov (United States)

    Traversi, R; Becagli, S; Castellano, E; Maggi, V; Morganti, A; Severi, M; Udisti, R

    2007-07-02

    A Flow Injection Analysis (FIA) spectrofluorimetric method for calcium determination in ice cores was optimised in order to achieve better analytical performances which would make it suitable for reliable calcium measurements at ppt level. The method here optimised is based on the formation of a fluorescent compound between Ca and Quin-2 in buffered environment. A careful evaluation of operative parameters (reagent concentration, buffer composition and concentration, pH), influence of interfering species possibly present in real samples and potential favourable effect of surfactant addition was carried out. The obtained detection limit is around 15 ppt, which is one order of magnitude lower than the most sensitive Flow Analysis method for Ca determination currently available in literature and reproducibility is better than 4% for Ca concentrations of 0.2 ppb. The method was validated through measurements performed in parallel with Ion Chromatography on 200 samples from an alpine ice core (Lys Glacier) revealing an excellent fit between the two chemical series. Calcium stratigraphy in Lys ice core was discussed in terms of seasonal pattern and occurrence of Saharan dust events.

  17. Sensitive Bromatometric Methods for the Determination of Sumatriptan Succinate in Pharmaceutical Formulations

    Directory of Open Access Journals (Sweden)

    K. V. V. Satyanarayana

    2011-01-01

    Full Text Available Two simple and sensitive spectrophotometric methods are described for the determination of sumatriptan succinate (STS in pure and tablets using bromate-bromide as the bromination reagent in acid medium and two dyes as subsidiary reagents. The two methods are based on the bromination of STS by a known excess of in situ generated bromine followed by determination of unreacted bromine by reacting with a fixed amount of methyl orange (Method A or indigo carmine (Method B and measuring the absorbance at 508 or 610 nm. In both methods, the amount of bromine reacted corresponds to the amount of STS. The experimental conditions for the assay have been optimized. In two methods, the absorbance was found to increase linearly with the concentration of STS at the respective wavelengths. Beer’s law was obeyed over the ranges 0.2-1.6 and 2.0-12.0 μg mL-1 for method A and method B respectively and the respective molar absorptivity values were 1.898×105 and 2.71×104 L mol-1 cm-1. The statistical analysis of the methods was validated according to the present ICH guidelines. The proposed methods were applied to the analysis of tablet form of STS and the results tallied well with the label claim.

  18. A new sensitive flow-injection chemiluminescence method for the determination of H(2)-receptor antagonists.

    Science.gov (United States)

    Tang, Yu-Hai; Wang, Nan-Nan; Xiong, Xun-Yu; Xiong, Feng-Mei; Sun, Si-Juan

    2007-01-01

    Based on the chemiluminescence (CL) intensity generated from the potassium ferricyanide [K(3)Fe(CN)(6)]-rhodamine 6G system in sodium hydroxide (NaOH) medium, a new sensitive flow-injection chemiluminescence (FI-CL) method has been developed, validated and applied for the determination of three kinds of H(2)-receptor antagonists: cimetidine (CIMT), ranitidine (RANT) hydrochloride and famotidine (FAMT). Under the optimum conditions, the linear range for the determination was 1.0 x 10(-9)-7.0 x 10(-5) g/ml for CIMT, 1.0 x 10(-9)-5.0 x 10(-5) g/mL for RANT hydrochloride and 5.0 x 10(-9)-7.0 x 10(-5) g/mL for FAMT. During 11 repeated measurements of 1.0 x 10(-6) g/mL sample solutions, the relative standard deviations (RSDs) were all <5%. The detection limit was 8.56 x 10(-10) g/mL for CIMT, 8.69 x 10(-10) g/mL for RANT hydrochloride and 2.35 x 10(-9) g/mL for FAMT (S:N = 3). This method has been successfully implemented for the analysis of H(2)-receptor antagonists in pharmaceuticals.

  19. Selective and Sensitive Chemiluminescence Determination of MCPB: Flow Injection and Liquid Chromatography.

    Science.gov (United States)

    Meseguer-Lloret, Susana; Torres-Cartas, Sagrario; Catalá-Icardo, Mónica; Gómez-Benito, Carmen

    2016-02-01

    Two new chemiluminescence (CL) methods are described for the determination of the herbicide 4-(4-chloro-o-tolyloxy) butyric acid (MCPB). First, a flow injection chemiluminescence (FI-CL) method is proposed. In this method, MCPB is photodegraded with an ultraviolet (UV) lamp and the photoproducts formed provide a great CL signal when they react with ferricyanide in basic medium. Second, a high-performance liquid chromatography chemiluminescence (HPLC-CL) method is proposed. In this method, before the photodegradation and CL reaction, the MCPB and other phenoxyacid herbicides are separated in a C18 column. The experimental conditions for the FI-CL and HPLC-CL methods are optimized. Both methods present good sensitivity, the detection limits being 0.12 µg L(-1) and 0.1 µg L(-1) (for FI-CL and HPLC-CL, respectively) when solid phase extraction (SPE) is applied. Intra- and interday relative standard deviations are below 9.9%. The methods have been satisfactorily applied to the analysis of natural water samples. FI-CL method can be employed for the determination of MCPB in simple water samples and for the screening of complex water samples in a fast, economic, and simple way. The HPLC-CL method is more selective, and allows samples that have not been resolved with the FI-CL method to be solved.

  20. A rapid and sensitive spectrophotometric method for the determination of benzoyl peroxide in wheat flour samples

    Directory of Open Access Journals (Sweden)

    Kraingkrai Ponhong

    2015-12-01

    Full Text Available A simple, rapid, and sensitive spectrophotometric method for the determination of benzoyl peroxide (BPO in wheat flour samples was developed. The detection principle is based on BPO reacted with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS to obtain a blue-green colored product that was detected at 415 nm by spectrophotometry. The effect of factors influencing the color reaction was investigated. Under the selected conditions, the linear range for quantification of BPO was observed between 0.2–1.0 mg L−1 with r2 = 0.998. The limit of detection (LOD was 0.025 mg L−1. The developed method obtained superior precision (relative standard deviation < 2% using 11 repeatability at 0.2 mg L−1, 0.6 mg L−1, and 0.8 mg L−1. The proposed methodology was successfully applied to determine BPO in wheat flour samples.

  1. Inhibition of HIV-1 entry by the tricyclic coumarin GUT-70 through the modification of membrane fluidity

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Kouki; Hattori, Shinichiro; Kariya, Ryusho [Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811 (Japan); Komizu, Yuji [Division of Applied Life Science, Graduate School of Engineering, Sojo University, 4-22-1 Ikeda, Nishi-ku, Kumamoto 860-0082 (Japan); Kudo, Eriko; Goto, Hiroki; Taura, Manabu [Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811 (Japan); Ueoka, Ryuichi [Division of Applied Life Science, Graduate School of Engineering, Sojo University, 4-22-1 Ikeda, Nishi-ku, Kumamoto 860-0082 (Japan); Kimura, Shinya [Division of Hematology, Respiratory Medicine and Oncology, Department of Internal Medicine, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Okada, Seiji, E-mail: okadas@kumamoto-u.ac.jp [Division of Hematopoiesis, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811 (Japan)

    2015-02-13

    Membrane fusion between host cells and HIV-1 is the initial step in HIV-1 infection, and plasma membrane fluidity strongly influences infectivity. In the present study, we demonstrated that GUT-70, a natural product derived from Calophyllum brasiliense, stabilized plasma membrane fluidity, inhibited HIV-1 entry, and down-regulated the expression of CD4, CCR5, and CXCR4. Since GUT-70 also had an inhibitory effect on viral replication through the inhibition of NF-κB, it is expected to be used as a dual functional and viral mutation resistant reagent. Thus, these unique properties of GUT-70 enable the development of novel therapeutic agents against HIV-1 infection.

  2. Polymorphism of CYP11B2 determines salt sensitivity in Japanese.

    Science.gov (United States)

    Iwai, Naoharu; Kajimoto, Kazuaki; Tomoike, Hitonobu; Takashima, Naoyuki

    2007-04-01

    Aldosterone plays essential roles in body fluid and electrolyte homeostasis and blood pressure. However, the association between polymorphisms in the CYP11B2 gene and hypertension is controversial. We resequenced CYP11B1 and CYP11B2 and identified 35 polymorphisms in this region. We performed association studies between the plasma aldosterone concentration and 13 polymorphisms in this region in 1443 subjects. The subjects were all obtained from the Suita Cohort Study. Multiple regression analysis indicated that aldosterone levels were determined by renin activity, age, total cholesterol, and hematocrit. Residuals of the aldosterone levels after adjusting for these confounding factors were nominally associated with the T(-344)C (P=0.0026), C(595)T (P=0.0180), -(4837)C (P=0.0310), and G(4936)A (P=0.0498) polymorphisms. Only the T(-344)C polymorphism was significantly associated with the aldosterone level after a correction for multiple testing (Bonferroni). A significant interaction was observed between the T(-344)C polymorphism and renin activity in determining aldosterone levels. Moreover, a significant interaction was observed in 2063 subjects between urinary sodium excretion, which reflects sodium intake, and the T(-344)C polymorphism in determining systolic blood pressure. Only subjects with the TT genotype showed a positive correlation between urinary sodium excretion and systolic blood pressure. In vitro experiments confirmed the functional significance of this T(-344)C polymorphism in terms of angiotensin II reactivity. Thus, the T(-344)C polymorphism in CYP11B2 appears to affect salt sensitivity in Japanese and to have clinical significance.

  3. Assessment of the Role of Metabolic Determinants on the Relationship between Insulin Sensitivity and Secretion

    Science.gov (United States)

    Galgani, Jose E.; Gómez, Carmen; Mizgier, Maria L.; Gutierrez, Juan; Santos, Jose L.; Olmos, Pablo; Mari, Andrea

    2016-01-01

    Background Insulin secretion correlates inversely with insulin sensitivity, which may suggest the existence of a crosstalk between peripheral organs and pancreas. Such interaction might be mediated through glucose oxidation that may drive the release of circulating factors with action on insulin secretion. Aim To evaluate the association between whole-body carbohydrate oxidation and circulating factors with insulin secretion to consecutive oral glucose loading in non-diabetic individuals. Methods Carbohydrate oxidation was measured after an overnight fast and for 6 hours after two 3-h apart 75-g oral glucose tolerance tests (OGTT) in 53 participants (24/29 males/females; 34±9 y; 27±4 kg/m2). Insulin secretion was estimated by deconvolution of serum C-peptide concentration, β cell function by mathematical modelling and insulin sensitivity from an OGTT. Circulating lactate, free-fatty acids (FFA) and candidate chemokines were assessed before and after OGTT. The effect of recombinant RANTES (regulated on activation, normal T cell expressed and secreted) and IL8 (interleukin 8) on insulin secretion from isolated mice islets was also measured. Results Carbohydrate oxidation assessed over the 6-h period did not relate with insulin secretion (r = -0.11; p = 0.45) or β cell function indexes. Circulating lactate and FFA showed no association with 6-h insulin secretion. Circulating chemokines concentration increased upon oral glucose stimulation. Insulin secretion associated with plasma IL6 (r = 0.35; p<0.05), RANTES (r = 0.30; p<0.05) and IL8 (r = 0.41; p<0.05) determined at 60 min OGTT. IL8 was independently associated with in vivo insulin secretion; however, it did not affect in vitro insulin secretion. Conclusion Whole-body carbohydrate oxidation appears to have no influence on insulin secretion or putative circulating mediators. IL8 may be a potential factor influencing insulin secretion. PMID:28002466

  4. 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

  5. Crop kites: Determining crop-water production functions using crop coefficients and sensitivity indices

    Science.gov (United States)

    Smilovic, Mikhail; Gleeson, Tom; Adamowski, Jan

    2016-11-01

    The crop-water production function quantitatively evaluates the relationship between seasonal water use and crop yield and is used to evaluate optimal irrigation depth and assess the potential of deficit and supplemental irrigation. A simple and easily applicable methodology to develop crop- and region-specific crop-water production functions using crop coefficients and sensitivity-indices is presented. Previous efforts to describe the crop-water production function have not accounted for the effects of the temporal distribution of water use and trivialize the associated variability in yields by assuming an optimized or arbitrary temporal distribution. The temporal distribution of water use throughout the growing season can significantly influence crop yield, and the ability of farmers to manage both the timing and amount of irrigation water may result in higher yields. We propose crop kites, a tool that explicitly acknowledges crop yield as a function of the temporal distribution of water use to both evaluate the complete space of water use and crop yield relationships, and extract from this space specific crop-water production functions. An example for winter wheat is presented using previously validated crop-specific sensitivity indices. Crop-water production functions are extracted from the crop kite related to specific irrigation schedules and temporal distributions of water use. Crop-water production functions associated with maximizing agricultural production agree with previous efforts characterizing the shape as a diminishing curvilinear function. Crop kites provide the tools for water managers and policy makers to evaluate crop- and region-specific agricultural production as it relates to water management and the associated economics, and to determine appropriate policies for developing and supporting the infrastructure to increase water productivity.

  6. 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

  7. Determination of Water Sensitivity Index in EstakoWest and Esan Central, Nigeria

    Directory of Open Access Journals (Sweden)

    Philipa O. Idogho

    2014-07-01

    Full Text Available As world population and industrial-agricultural outputs have increased, the use of water has accelerated. This development leads to extreme difficulty to provide sufficient safe drinking water in Etasko-West and Esan Central. Water sensitivity was measured in six major towns in Etasko-West and Esan Central. Water Measuring Indicators such as Water Poverty Index-Real Time (WPIr, Water Factor Value (WFV and Access-Demand Factor (γ were applied to generate water sensitivity iterations. The outputs of these iterations show that Irrua has the fairest water supply and distribution with WPIr, WFA and γ index value of 0.22; 0.77 and 0.76, while Auchi and Ewu experience acute water shortage with the following index values: WPIr-0.43, 0.39; WFV-0.06, 0.16; and γ-0.64, 0.6 respectively. Results of One-Sample Test and Paired Sample Statistics show that the proportion of monthly income spent on portable water is significant at 0.95 confidence interval in all towns, except Auchi. Comparative analysis indicates strong relationship (R 2=0.667 between the resources spent in procuring clean water and accessibility-demand ratio in the region. Private sector participation recorded highest investment value of 62% on water sector; government and corporate organization recorded 23% and 15% respectively. Since private sector determines the progresses of water sector, this accounts for the exorbitant tariff of 1, 500 N per m 3 in this region. It is deduced that the most significant problems faced with water accessibility-affordability are transportation, finance and power supply with computed constraint index value of 47%, 40% and 13% respectively. Finally, Etasko-West and Esan Central are highly waterstressed. Government, corporate organization and private investors need to establish technically-based measures to ensure perfect accessibility and affordability of this scarce utility.

  8. 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.

  9. Free to Be You and Me: Normal Gender-Role Fluidity--Commentary on Diane Ehrensaft's "Listening and Learning from Gender-Nonconforming Children".

    Science.gov (United States)

    Knight, Rona

    2014-01-01

    This paper suggests that gender role fluidity is a normal self state throughout development. It discusses the nonlinear progression of gender role identity that is constantly fluid and reactive to biological, environmental, and psychological changes. Given the normal fluidity of gender role identity, it argues that giving puberty blockers to young children is against the best interests of the child's development.

  10. Sensitivity and specificity of serology in determining recent acute Campylobacter infection.

    Science.gov (United States)

    Taylor, B V; Williamson, J; Luck, J; Coleman, D; Jones, D; McGregor, A

    2004-05-01

    The measurement of serum antibodies to Campylobacter spp. has been used to investigate links between prior Campylobacter infections and the development of Guillain-Barre syndrome and its variants. Little is known of the serum antibody response to acute infections in the short- or long-term. The aims of the present study were to investigate the normal serum response to an acute Campylobacter infection and the sensitivity and specificity of anti-Campylobacter antibodies in determining recent Campylobacter infection. An enzyme-linked immunosorbent assay (ELISA) method was used to measure serum anti-Campylobacter immunoglobulin G (IgG), IgA and IgM antibodies. Controls consisted of 420 blood donors without recent gastroenteritis, 25 patients with other gastrointestinal infections, 24 patients with neurological conditions not affecting the peripheral nerves and 19 patients with autoimmune disorders. Three patient groups were assessed: 99 patients with acute Campylobacter infections, all of whom were tested 3 weeks post-infection; 69 of these patients tested 3-6 months later; and 74 additional patients tested >20 months post-infection. Western blot analysis was performed on controls and patients with high titre anti-Campylobacter antibodies to assess for cross-reactivity and specificity. Following acute infections, all antibody classes rose in the majority of but not in all patients, followed by decreasing titres that did not return to baseline levels. Sixteen per cent of enteritis cases did not demonstrate a rise in titres and 9% of cases had significant levels of antibodies >20 months post-infection. The ELISA used was shown to be highly specific for the detection of Campylobacter antibodies. The use of Campylobacter-specific antibody levels as the sole marker of prior infection is an unreliable method of determining the association between Campylobacter infection and neurological disease.

  11. 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.

  12. Sensitive immunochemical approaches for quantitative (FPIA) and qualitative (lateral flow tests) determination of gentamicin in milk.

    Science.gov (United States)

    Beloglazova, N V; Shmelin, P S; Eremin, S A

    2016-01-01

    Three kinds of immunoassays for the determination of gentamicin in milk samples were developed and validated. First, a fast and easily-performed fluorescence polarization immunoassay was used for characterization of the employed polyclonal antibody. The calculated Kaff were (1.9±0.4)×10(9)М(-1) and (6.0±0.2)×10(6)М(-1) for the high- and low-affinity fractions respectively. The assay was characterized with a good sensitivity, the limit of detection being 5μgkg(-1). Two different kinds of detection labels, i.e. colloidal gold (CG) and quantum dots (QDs), were evaluated for use in lateral-flow format with respect to rapid visual on-site testing. The cut-off levels for both qualitative formats were selected based on the maximum level for gentamicin in milk established by the European Commission, 100μgkg(-1), resulting in a 10μgkg(-1) cut-off considering sample dilution. The intra-laboratory validation was performed with sterilized milk samples artificially spiked with gentamicin at concentrations less than, equal to, and greater than the cut-off level. It was shown that milk products could be analyzed without any sample preparation, except for dilution with the buffer solution. The rates of false-positive and false-negative results were below 5% for both labels. The different developed immunoassays were tested towards gentamicin determination in artificially-spiked and naturally contaminated milk samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. High-performance liquid chromatographic determination of memantine hydrochloride in rat plasma using sensitive fluorometric derivatization.

    Science.gov (United States)

    Xie, Mei-Fen; Zhou, Wei; Tong, Xin-Yi; Chen, Yi-Le; Cai, Yi; Li, Yan; Duan, Geng-Li

    2011-02-01

    In this study, we investigated a simple, sensitive and reliable liquid chromatography-fluorescence detection method for the determination of memantine hydrochloride in rat plasma which was based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). For the first time, FMOC-Cl was introduced into derivatization of memantine hydrochloride in rat plasma. The amino groups of memantine hydrochloride and amantadine hydrochloride (internal standard) were trapped with FMOC-Cl to form memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions, which can be very compatible for LC-FLD. Precipitation of plasma proteins by acetonitrile was followed by vortex mixing and centrifugation. Chromatographic separation was performed on a C(18) column (DIAMONSIL 150 × 4.6 mm, id 5 μm) with a mobile phase consisting of acetonitrile and water at a flow rate of 1.0 mL/min. The retention times of memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions were 23.69 and 40.27 min, respectively. Optimal conditions for the derivatization of memantine hydrochloride were also described. The limit of quantification (LOQ) was 25 ng/mL for memantine hydrochloride in plasma, the linear range was 0.025-5.0 μg/mL in plasma with a correlation coefficient (r) of 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day assays were 4.46-12.19 and 5.23-11.50%, respectively. The validated method was successfully applied to the determination of memantine hydrochloride in rat plasma samples.

  14. Factors determining sensitivity and resistance of tumor cells to arsenic trioxide.

    Directory of Open Access Journals (Sweden)

    Serkan Sertel

    Full Text Available Previously, arsenic trioxide showed impressive regression rates of acute promyelocytic leukemia. Here, we investigated molecular determinants of sensitivity and resistance of cell lines of different tumor types towards arsenic trioxide. Arsenic trioxide was the most cytotoxic compound among 8 arsenicals investigated in the NCI cell line panel. We correlated transcriptome-wide microarray-based mRNA expression to the IC(50 values for arsenic trioxide by bioinformatic approaches (COMPARE and hierarchical cluster analyses, Ingenuity signaling pathway analysis. Among the identified pathways were signaling routes for p53, integrin-linked kinase, and actin cytoskeleton. Genes from these pathways significantly predicted cellular response to arsenic trioxide. Then, we analyzed whether classical drug resistance factors may also play a role for arsenic trioxide. Cell lines transfected with cDNAs for catalase, thioredoxin, or the anti-apoptotic bcl-2 gene were more resistant to arsenic trioxide than mock vector transfected cells. Multidrug-resistant cells overexpressing the MDR1, MRP1 or BCRP genes were not cross-resistant to arsenic trioxide. Our approach revealed that response of tumor cells towards arsenic trioxide is multi-factorial.

  15. A system for determining the pharmacology of indirect radiation sensitizer drugs on multicellular spheroids

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, N.; Bicher, H.I.; Hetzel, F.W.; Brown, M.

    1981-01-01

    We have characterized some of the physiology of multicellular spheroids of different sizes grown from Chinese hamster lung fibroblast (V79) cells. Among the parameters studied were oxygen tension distributions within the spheroid. This was achieved using ultramicroelectrodes with tip diameters of 1-5 mu and a perfusion system whereby environmental conditions such as flow, temperature, and chemical makeup of the milieu could be measured and controlled. Plateau pO/sup 2/ values of less than 10 mm Hg were consistently obtained from spheroids under various conditions. We were able to modify these distributions by use of indirect radiation sensitizer drugs such as mechlorethamine HCl (mustargen) at nontoxic doses. We have also made determinations of the inhibitory capacities of several other drugs on the respiration rate of constituent cells of multicellular spheroids in single-cell suspensions. We have concluded that there are indeed hypoxic cells in spheroids whose radioresistance may be modified by essentially nontoxic levels of indirect radiosensitizer drugs and that the system described shows great promise for screening agents which may modify radiation response.

  16. A more sensitive radioimmunoassay for neuron-specific enolase suitable for cerebrospinal fluid determinations.

    Science.gov (United States)

    Parma, A M; Marangos, P J; Goodwin, F K

    1981-03-01

    Neuron-specific enolase (NSE) and non-neuronal enolase (NNE) have been shown to be highly specific neuronal and glial products respectively and are therefore useful as biochemical markers of the two major cell types in the vertebrate central nervous system. An iodinated radioimmunoassay (RIA) procedure for human NSE (NSE-H) with approximately 50-fold greater sensitivity than the previously available tritiated assay is described. This assay is capable of detecting 100 pg of NSE-H per assay. NSE levels in human cerebrospinal fluid (CSF) which were previously undetectable with the tritiated RIA are now easily measured and have been shown to be approximately 2 ng/ml of CSF. Furthermore, results obtained with the newly described assay procedure on more concentrated brain tissue extracts are comparable to the tritiated RIA. The iodinated NSE RIA is also shown to be capable of accurately detecting added amounts of NSE in human CSF, indicating the potential clinical usefulness of this assay in determining elevated levels of NSE in CSF.

  17. Proteinase K activity determination with β-galactosidase as sensitive macromolecular substrate.

    Science.gov (United States)

    Ghéczy, Nicolas; Küchler, Andreas; Walde, Peter

    2016-11-15

    Proteinase K from Engyodontium album (proK) is a relatively unspecific serine endopeptidase which is known to attack proteins yet in their native states. If the attacked protein is an enzyme, even a partial hydrolysis by proK may lead to an inactivation of the enzyme, which can be monitored by measuring the loss of catalytic activity of the attacked enzyme. E. coli β-galactosidase (β-Gal) was used in this work as such enzyme. It was found to be a convenient and sensitive macromolecular model substrate for comparing the "native protein-attacking ability" of free and immobilized proK at pH = 7.0 and 23 °C. The β-Gal activity was measured spectrophotometrically with o-nitrophenyl-β-galactopyranoside. Reproducible proK determinations were possible for as little as 4.3 ng proK by using a proK analyte solution of 10 nM. Compared to free proK, immobilized proK was much less efficient in inactivating β-Gal, most likely due to a decreased mobility of immobilized proK and a restricted accessibility of β-Gal to the active site of proK. Worth noting is, that under conditions at which β-Gal was completely inactivated by proK, the activity of hen egg lysozyme, horseradish peroxidase, or Aspergillus sp. glucose oxidase remained unaltered.

  18. 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.

  19. Sensitive determination of ranitidine in rabbit plasma by HPLC with fluorescence detection.

    Science.gov (United States)

    Khedr, Alaa

    2008-02-01

    A sensitive high-performance liquid chromatographic method for determination of ranitidine (RAN) in rabbit plasma is described. The method is based on liquid-liquid extraction, labeling with dansyl chloride and monitoring with fluorescence detector at 338nm (ex)/523nm (em). Plasma samples were extracted with diethyl ether alkalinized with 1M sodium hydroxide. Ephedrine HCl (EPH-HCl) was used as internal standard. Both, RAN and EPH were completely derivatized after heating at 60 degrees C for 10min in sodium bicarbonate solution (pH 9.5). The derivatized samples were analyzed by HPLC using Agilent Zorbax Extended C18 column (150mmx4.6mm i.d.) and mobile phase consists of 48% acetonitrile and 52% sodium acetate solution (0.02M, pH 4.6). The linearity of the method was in the range of 0.025-10microg/ml. The limits of detection (LOD) and quantification (LOQ) were 7.5+/-0.18 and 22.5+/-0.12ng/ml, respectively. Ranitidine recovery was 97.5+/-1.1% (n=6; R.S.D.=1.8%). The method was applied on plasma collected from rabbits at different time intervals after oral administration of 5mg/kg ranitidine HCl.

  20. Aging process on spectrally determined spontaneous baroreflex sensitivity: a 5-year prospective study.

    Science.gov (United States)

    Fauvel, Jean-Pierre; Cerutti, Catherine; Mpio, Ignace; Ducher, Michel

    2007-09-01

    The interindividual age-related decrease in baroreflex sensitivity (BRS) was reported in many cross-sectional studies. However, the long-term intraindividual decrease in BRS has never been confirmed by longitudinal studies. Data obtained from a 5-year prospective study designed to assess the 5-year stress effects on blood pressure (BP) provided the opportunity to assess longitudinal aging process on spectrally determined BRS (S-BRS) using the cross spectral analysis. This analysis was carried out in 205 men aged between 18 and 50 years who had 2 valid beat to beat BP recordings (Finapress) at a mean 5-year interval. At inclusion and at end of follow-up, S-BRS was significantly correlated with age (r=-0.50, P<0.001, r=-0.33, P<0.001 respectively). Interestingly, the slopes and the intercepts were not significantly different at a 5-year interval. This result is in favor of the good reproducibility of S-BRS. The attenuation with age of S-BRS was calculated at 3.6% a year. This decrease was slightly higher than the one obtained with the baseline data (2.3% per year). This longitudinal study provided, for the first time, an estimate of the slope of the age-related physiological S-BRS decrease in a mid-aged healthy male population. Our findings reinforce the interest of evaluating spontaneous BRS reported to predict hypertension and cardiovascular events in various populations.

  1. Quantum dots and p-phenylenediamine based method for the sensitive determination of glucose.

    Science.gov (United States)

    Lv, Xiaoxiao; Wang, Xiaoyu; Huang, Dawei; Niu, Chenggang; Zeng, Guangming; Niu, Qiuya

    2014-11-01

    By introducing p-phenylenediamine (PPD) to the hybrid system of Mn-doped CdS/ZnS quantum dots (QDs) and glucose oxidase (GOD), a sensitive label-free method was proposed for direct detection of glucose. With glucose and PPD as substrates, 2,5-diamino-N,N'-di-(4-aminophenyl)-2,5-cyclohexadiene-1,4-diimine (DDACD) that intensively quenches the fluorescence of QDs can be produced by the catalysis of GOD. A detection limit as low as 3.2 μM was obtained with the high-efficient fluorescence quencher. Two linear ranges, from 5.0 μM to 1000 μM and from 1.0 mM to 10.0 mM, were identified between time-gated fluorescence intensity and the concentration of glucose. It is shown that the newly proposed methods have high selectivity for glucose over other saccharides and coexisting biological species in serum. The method can be used directly to determine glucose in normal adult human serum without any complicated sample pretreatments. The recovery rate and repeatability of the method were also shown to be satisfactory.

  2. 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.

  3. A Highly Sensitive Resonance Rayleigh Scattering Method for the Determination of Penicillin Antibiotics with Potassium Ferricyanide

    Institute of Scientific and Technical Information of China (English)

    DUAN Hui; LIU Zhong-Fang; LIU Shao-Pu; KONG Ling

    2008-01-01

    Heated in a boiling water bath, penicillin antibiotics such as amoxicillin, ampicillin, sodium cloxacillin, sodium carbenicillin and sodium benzylpenicillin could react with K3[Fe(CN)6] to form combined products in a dilute HCl medium.As a result, resonance Rayleigh scattering (RRS) intensity was enhanced greatly and new RRS spectra appeared.The maximum scattering wavelengths of the five combined products are all located at 330 nm.The scattered intensity increments (△I) of the combined products are directly proportional to the concentrations of the antibiotics in a certain range.The methods exhibit high sensitivity, and the detection limits for the five penicillin antibiotics are between 4.61 and 5.62 ng·mL-1.The spectral characteristics of RRS and the optimum reaction conditions were investigated.The mechanism of reaction and the reasons for the enhancement of resonance light scattering were discussed.The effects of coexisting substances have been examined, and the results indicated that the method had a good selectivity.It can be applied to the determination of penicillin antibiotics in capsule, tablet, human serum and urine samples.

  4. Based on magnetic graphene oxide highly sensitive and selective imprinted sensor for determination of sunset yellow.

    Science.gov (United States)

    Li, Jianbo; Wang, Xiaojiao; Duan, Huimin; Wang, Yanhui; Bu, Yanan; Luo, Chuannan

    2016-01-15

    A new imprinted material based on β-cyclodextrin/ionic liquid/gold nanoparticles functionalized magnetic graphene oxide has been successfully synthesized and modified to the glassy carbon electrode surface to constructed imprinted electrochemical sensor to detect sunset yellow. The sensitivity and electrochemical response of the electrode can be improved by nanomaterials. The surface morphology and crystal structure of the hybrid nanomaterial has been characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy. The electrochemical behaviors of the hybrid nanomaterials based sensor were evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. Under the optimized conditions, the proposed electrochemical sensor showed a fast rebinding dynamics, which was successfully applied to sunset yellow detection with a wide linear range from 5.0×10(-9) to 2.0×10(-6)mol L(-1) and a detection limit of 2.0×10(-9)mol L(-1). The electrochemical sensor has been successfully applied in the determination of SY in spiked water samples, mirinda drink and minute maid, and the recoveries for the standards added are 97-105%.

  5. Multiwalled carbon nanotubes/gold nanocomposites-based electrochemiluminescent sensor for sensitive determination of bisphenol A.

    Science.gov (United States)

    Guo, Weiwei; Zhang, Amin; Zhang, Xin; Huang, Chusen; Yang, Dapeng; Jia, Nengqin

    2016-10-01

    An electrochemiluminescence (ECL) sensor for bisphenol A was proposed by using L-cysteine-functionalized multiwalled carbon nanotubes/gold nanocomposites-modified glassy carbon electrode (MWCNTs-Au/GCE) based on ECL of peroxydisulfate solution. The ECL behaviors of peroxydisulfate solution had been investigated at the chitosan/MWCNTs-Au/GCE, and bisphenol A was found to have quenching effects on the ECL of peroxydisulfate solution. Both Au nanoparticles (AuNPs) and multiwalled CNTs could promote the electron transfer and synergetically amplify the ECL signal of peroxydisulfate solution. Under the optimized conditions, the ECL signal intensity was linear with the concentration of bisphenol A in the concentration range between 0.25 and 100 μM (R = 0.9931) with a detection limit (S/N = 3) of 0.083 μM. The constructed ECL sensor has the advantages of simplicity, sensitivity, good selectivity, and reproducibility, exhibiting a great potential application in the determination of bisphenol A.

  6. Thermal sensitivity does not determine acclimation capacity for a tropical reef fish.

    Science.gov (United States)

    Donelson, Jennifer M; Munday, Philip L

    2012-09-01

    1. Short-term measures of metabolic responses to warmer environments are expected to indicate the sensitivity of species to regional warming. However, given time, species may be able to acclimate to increasing temperature. Thus, it is useful to determine if short-term responses provide a good predictor for long-term acclimation ability. 2. The tropical reef fish Acanthochromis polyacanthus was used to test whether the ability for developmental thermal acclimation of two populations was indicated by their short-term metabolic response to temperature. 3. While both populations exhibited similar short-term responses of resting metabolic rate (RMR) to temperature, fish from the higher-latitude population were able to fully acclimate RMR, while the lower-latitude population could only partially compensate RMR at the warmest temperature. These differences in acclimation ability are most likely due to genetic differences between the populations rather than differences in thermal regimes. 4. This research indicates that acclimation ability may vary greatly between populations and that understanding such variation will be critical for predicting the impacts of warming environmental temperatures. Moreover, the thermal metabolic reaction norm does not appear to be a good predictor of long-term acclimation ability.

  7. Sensitive method for determination of DON in cocoa by means of HPLC-techniques.

    Science.gov (United States)

    Raters, M; Matissek, R

    2007-12-01

    The mycotoxin deoxynivalenol (DON) is one of a group of mycotoxins known as type B trichothecenes and is particularly formed by the mould speciesFusarium graminearum andFusarium culmorum. The frequency of the occurrence of DON in certain raw materials and the concentrations found make it one of the world's most significant mycotoxin contaminants. Positive findings of the toxin especially have been established in cereal-based foods, as well as in oilseeds.The main objective of this study was to set up a current situation assessment of the possible occurrence of deoxynivalenol in cocoa and cocoa products. As there was no analytical method for determining DON in cocoa and cocoa products, a special method was developed. The applicability and consistency of the method was confirmed by performing recovery assays on various cocoa products. A special post-column derivatisation procedure was developed to increase selectivity and raise sensitivity by a factor of 80.The method was used to test 230 samples for possible DON content, ranging from cocoa beans to cocoa bean shells, nibs, cocoa liquor and cocoa powders through to finished cocoa-based products. The results suggest that DON may occasionally occur in cocoa beans in very low concentrations.

  8. BODIPY-Coumarin Conjugate as an Endoplasmic Reticulum Membrane Fluidity Sensor and Its Application to ER Stress Models.

    Science.gov (United States)

    Lee, Hoyeon; Yang, Zhigang; Wi, Youngjin; Kim, Tae Woo; Verwilst, Peter; Lee, Yun Hak; Han, Ga-In; Kang, Chulhun; Kim, Jong Seung

    2015-12-16

    An endoplasmic reticulum (ER) membrane-selective chemosensor composed of BODIPY and coumarin moieties and a long alkyl chain (n-C18) was synthesized. The emission ratio of BODIPY to coumarin depends on the solution viscosity. The probe is localized to the ER membrane and was applied to reveal the reduced ER membrane fluidity under ER stress conditions.

  9. Influence of Basicity and MgO on Fluidity and Desulfurization Ability of High Aluminum Slag

    Science.gov (United States)

    Wang, Ping; Meng, Qing-min; Long, Hong-ming; Li, Jia-xin

    2016-08-01

    The viscosity of experimental slag, which was mixed based on the composition of a practical blast furnace slag, was measured in this paper. The influence of Al2O3 and MgO content, basicity R2 = w(CaO)/w(SiO2) on the fluidity of slag was studied. The stepwise regression analysis in SPSS was used to reveal the relationship between sulfur distribution coefficient LS and slag composition as well as furnace temperature. The results show that increasing of MgO up to 12% can decrease the slag viscosity. The w(MgO) should be controlled below 8% when there is 20% Al2O3 in the slag. Temperature of hot metal and content of CaO in slag are the two dominant factors on the desulfurization capacity of slag.

  10. The membrane-induced structure of melittin is correlated with the fluidity of the lipids.

    Science.gov (United States)

    Andersson, August; Biverståhl, Henrik; Nordin, Jon; Danielsson, Jens; Lindahl, Emma; Mäler, Lena

    2007-01-01

    The effect of the bee toxin melittin on DMPC dynamics in fast-tumbling bicelles has been investigated. The (13)C R(1) and (13)C-(1)H NOE relaxation parameters for DMPC were used to monitor the effect of melittin and cholesterol on lipid dynamics. It was found that melittin has the largest effect on the DMPC mobility in DMPC/DHPC bicelles, while less effect was observed in cholesterol-doped bicelles, or in bicelles made with CHAPS, indicating that the rigidity of the membrane affects the melittin-membrane interaction. CD spectra were analysed in terms of cooperativity of the alpha-helix to random coil transition in melittin, and these results also indicated similar differences between the bicelles. The study shows that bicelles can be used to investigate lipid dynamics by spin relaxation, and in particular of peptide-induced changes in membrane fluidity.

  11. Increased Lipiodol uptake in hepatocellular carcinoma possibly due to increased membrane fluidity by dexamethasone and tamoxifen

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Stephanie, E-mail: stephanie.becker@rouen.fnclcc.f [Department of Nuclear Medicine, Centre E. Marquis, F-35042 Rennes (France); INSERM U 991, Rennes, F-35033 France (France); European University of Brittany, F-35000 Rennes (France); Department of Nuclear Medicine, Centre H. Becquerel, F-76038 Rouen (France); Ardisson, Valerie; Lepareur, Nicolas [Department of Nuclear Medicine, Centre E. Marquis, F-35042 Rennes (France); INSERM U 991, Rennes, F-35033 France (France); European University of Brittany, F-35000 Rennes (France); Sergent, Odile [European University of Brittany, F-35000 Rennes (France); UPRES EA SeRAIC, IFR 140, University of Rennes 1, F-35043 Rennes (France); Bayat, Sahar [INSERM U936 Department of Biostatistics, CHRU Pontchaillou, F-35033 Rennes (France); Noiret, Nicolas [European University of Brittany, F-35000 Rennes (France); Ecole Nationale Superieure de Chimie de Rennes, UMR CNRS 6226, F-35708 Rennes (France); Gaboriau, Francois; Clement, Bruno [INSERM U 991, Rennes, F-35033 France (France); Boucher, Evelyne [INSERM U 991, Rennes, F-35033 France (France); Department of Medical Oncology, Centre E. Marquis, F-35042 Rennes (France); Raoul, Jean-Luc [INSERM U 991, Rennes, F-35033 France (France); European University of Brittany, F-35000 Rennes (France); Department of Medical Oncology, Centre E. Marquis, F-35042 Rennes (France); Garin, Etienne [Department of Nuclear Medicine, Centre E. Marquis, F-35042 Rennes (France); INSERM U 991, Rennes, F-35033 France (France); European University of Brittany, F-35000 Rennes (France)

    2010-10-15

    Introduction: Lipiodol is used as a vector for chemoembolization or internal radiotherapy in unresectable hepatocellular carcinomas (HCCs). The aim of this study is to improve the tumoral uptake of Lipiodol by modulating membrane fluidizing agents to optimize the effectiveness of Lipiodol vectorized therapy. Methods: The effect of dexamethasone and tamoxifen on membrane fluidity was studied in vitro by electron paramagnetic resonance applied to rat hepatocarcinoma cell line N1S1. The tumoral uptake of Lipiodol was studied in vivo on rats with HCC, which had been previously treated by dexamethasone and/or tamoxifen, after intra-arterial administration of {sup 99m}Tc-SSS-Lipiodol. Results: The two molecules studied here exhibit a fluidizing effect in vitro which appears dependent on time and dose, with a maximum fluidity obtained after 1 hr at concentrations of 20 {mu}M for dexamethasone and 200 nM for tamoxifen. In vivo, while the use of dexamethasone or tamoxifen alone tends to lead to increased tumoral uptake of Lipiodol, this effect does not reach levels of significance. On the other hand, there is a significant increase in the tumoral uptake of {sup 99m}Tc-SSS-Lipiodol in rats pretreated by both dexamethasone and tamoxifen, with a tumoral uptake (expressed in % of injected activity per g of tumor) of 13.57{+-}3.65% after treatment, as against 9.45{+-}4.44% without treatment (P<.05). Conclusions: Dexamethasone and tamoxifen fluidify the N1S1 cells membrane, leading to an increase in the tumoral uptake of Lipiodol. These drugs could be combined with chemo-Lipiodol-embolization or radiolabeled Lipiodol, with a view to improving the effectiveness of HCCs therapy.

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

    Science.gov (United States)

    Kohn, Florian; Hauslage, Jens; Hanke, Wolfgang

    2017-06-01

    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.

  13. A sensitive diffusion sampler for the determination of volatile organic compounds in ambient air

    Science.gov (United States)

    Uchiyama, Shigehisa; Asai, Masae; Hasegawa, Shuji

    We developed a diffusive sampling device (DSD-voc) for volatile organic compounds (VOCs) which is suitable for collection of low level VOCs and analysis with thermal desorption. This sampling device is composed of two parts, an exposure part made of a porous polytetrafluoroethylene (PTFE) filter, and an analysis part made of stainless-steel tubing. The DSD-voc collects VOCs through the mechanism of molecular diffusion. Collection is controlled by moving the adsorbent from the exposure part to the analysis part by changing the posture of the DSD-voc. Adsorbates in the DSD-voc were analyzed by GC/MS with a thermal desorption cold trap injector (TCT). The TCT has the advantage of being able to accept the entire quantity of VOCs. We connected a condenser between the DSD-voc and the trap tube to prevent moisture from freezing in the trap tube when the sampler was packed with strong adsorbent. We also examined the desorption efficiency for VOCs from several types of adsorbents (Carboxen TM 1000, Carbosieve TM G, Carbosieve S III, Carbotrap TM B, and activated carbon) over a wide range of temperatures. Carboxen 1000 was suitable for the determination of VOCs with a low boiling point range, from CFC12 to hexane, while Carbotrap B was suitable for VOCs from hexane to 1,4-dichlorobenzene. The limits of detection with Carboxen 1000 and Carbotrap B were 0.036-0.046 and 0.0035-0.014 ppb, respectively, for a sampling duration of 24 h. Coefficients of variation for concentrations of major VOCs ranged from 3.8 to 14%. It is possible to estimate atmospheric VOCs at sub-parts per billion (sub-ppb), with high sensitivity, by using both adsorbents in combination.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Semie; Kim, Il Han [College of Medicine, Seoul National Univ., Seoul (Korea, Republic of)

    2001-06-01

    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{sup 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{sup 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

  15. Diagnostic Utility of Chest X-rays in Neonatal Respiratory Distress: Determining the Sensitivity and Specificity

    Directory of Open Access Journals (Sweden)

    Hassan Mottaghi Moghadam shahri

    2014-11-01

    Full Text Available Background: Chest radiography is one of the most usual diagnostic tools for respiratory distress. Objective: The purpose of this study is to assess the specificity, sensitivity and clinical value of chest radiography of neonates with respiratory distress.Patients and Methods: A descriptive- analytical study was conducted on 102 neonates that were in neonatal intensive care unit of Imam Reza and 22 Bahman Hospitals because of respiratory distress. After confirming the neonate's respiratory distress and taking chest radiography, the radiography was described by a radiologist and final diagnosis was confirmed. Results: Most of the neonates (64.7% were born with caesarian section and were premature (78.4%. Respiratory distress syndrome (RDS was the most common reason for respiratory distress (38.2%. Chest radiography had the most sensitivity and specificity in pneumothorax and hernia (100%. For pneumosepsis, radiography had 73% sensitivity and 87% specificity, for RDS the sensitivity and specificity were 35% and 82% respectively, for congenital heart disease sensitivity of zero and specificity of 98% and for Transient tachypnea of neonates (TTN sensitivity of zero and specificity of 100%. The conformity of clinical and radiography was also calculated as 79.4% in respiratory distress Discussion and Conclusion: Although chest radiography is used as one of the most usual and accessible diagnostic tools in respiratory distress syndrome, but inaccurate specificity and sensitivity in some disease must be considered, especially in neonates.

  16. Bioluminometric assay of ATP in mouse brain: Determinant factors for enhanced test sensitivity

    Indian Academy of Sciences (India)

    Haseeb Ahmad Khan

    2003-06-01

    Firefly luciferase bioluminescence (FLB) is a highly sensitive and specific method for the analysis of adenosine-5-triphosphate (ATP) in biological samples. Earlier attempts to modify the FLB test for enhanced sensitivity have been typically based on in vitro cell systems. This study reports an optimized FLB procedure for the analysis of ATP in small tissue samples. The results showed that the sensitivity of the FLB test can be enhanced several fold by using ultraturax homogenizer, perchloric acid extraction, neutralization of acid extract and its optimal dilution, before performing the assay reaction.

  17. Fatness rather than leptin sensitivity determines the timing of puberty in female mice.

    Science.gov (United States)

    Bohlen, Tabata M; Silveira, Marina A; Zampieri, Thais T; Frazão, Renata; Donato, Jose

    2016-03-05

    Leptin is a permissive factor for the onset of puberty. However, changes in adiposity frequently influence leptin sensitivity. Thus, the objective of the present study was to investigate how changes in body weight, fatness, leptin levels and leptin sensitivity interact to control the timing of puberty in female mice. Pre-pubertal obesity, induced by raising C57BL/6 mice in small litters, led to an early puberty onset. Inactivation of Socs3 gene in the brain or exclusively in leptin receptor-expressing cells reduced the body weight and leptin levels at pubertal onset, and increased leptin sensitivity. Notably, these female mice exhibited significant delays in vaginal opening, first estrus and onset of estrus cyclicity. In conclusion, our findings suggest that increased leptin sensitivity did not play an important role in favoring pubertal onset in female mice. Rather, changes in pubertal body weight, fatness and/or leptin levels were more important in influencing the timing of puberty.

  18. Ag Nanoparticles-enhanced Fluorescence of Terbium-Deferasirox Complexes for the Highly Sensitive Determination of Deferasirox.

    Science.gov (United States)

    Abolhasani, Jafar; Naderali, Roza; Hassanzadeh, Javad

    2016-01-01

    We describe the effect of different sized gold and silver nanoparticles on the terbium sensitized fluorescence of deferasirox. It is indicated that silver nanostructures, especially 18 nm Ag nanoparticles (AgNPs), have a remarkable amplifying effect compared to Au nanoparticles. Based on this observation, a highly sensitive and selective method was developed for the determination of deferasirox. Effects of various parameters like AgNPs and Tb(3+) concentration and pH of media were investigated. Under the optimal conditions, a calibration curve was plotted as the fluorescence intensities versus the concentration of deferasirox in the range of 0.1 to 200 nmol L(-1), and detection limit of 0.03 nmol L(-1) was obtained. The method has good linearity, recovery, reproducibility and sensitivity, and was satisfactorily applied for the determination of deferasirox in urine and pharmaceutical samples.

  19. 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.

  20. [Enzyme biosensors for penicillin determination based on conductometric planar electrodes and pH-sensitive field effect transistor].

    Science.gov (United States)

    Arkhipova, V N; Dziadevich, S V; Soldatkin, A P; El'skaia, A V

    1996-01-01

    The enzyme biosensors for penicillin determination based on conductometric planar electrodes and pH-sensitive field effect transistors have been described and their working parameters have been compared. The influence of pH, buffer capacity and ionic strength of the samples on the biosensors response has been studied. Short response time and high operational stability are characteristics of the developed biosensors.

  1. A simple and sensitive flow cytometric assay for determination of the cytotoxic activity of human natural killer cells

    NARCIS (Netherlands)

    Radosevic, Katarina; Radosevic, K.; Garritsen, Henk S.P.; Garritsen, H.S.P.; van Graft, M.; van Graft, Marja; de Grooth, B.G.; Greve, Jan

    1990-01-01

    A new, simple and sensitive flow cytometric assay for the determination of the cytotoxic activity of human natural killer cells is described. The assay is based on the use of two fluorochromes. The target cell population is stained with one fluorochrome (octadecylamine-fluorescein isothiocyanate,

  2. 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.

  3. Common genetic variation in the human CTF1 locus, encoding cardiotrophin-1, determines insulin sensitivity.

    Directory of Open Access Journals (Sweden)

    Stefan Z Lutz

    Full Text Available AIMS/HYPOTHESIS: Recently, cardiotrophin-1, a member of the interleukin-6 family of cytokines was described to protect beta-cells from apoptosis, to improve glucose-stimulated insulin secretion and insulin resistance, and to prevent streptozotocin-induced diabetes in mice. Here, we studied whether common single nucleotide polymorphisms (SNPs in the CTF1 locus, encoding cardiotrophin-1, influence insulin secretion and insulin sensitivity in humans. METHODS: We genotyped 1,771 German subjects for three CTF1 tagging SNPs (rs1046276, rs1458201, and rs8046707. The subjects were metabolically characterized by an oral glucose tolerance test. Subgroups underwent magnetic resonance (MR imaging/spectroscopy and hyperinsulinaemic-euglycaemic clamps. RESULTS: After appropriate adjustment, the minor allele of CTF1 SNP rs8046707 was significantly associated with decreased in vivo measures of insulin sensitivity. The other tested SNPs were not associated with OGTT-derived sensitivity parameters, nor did the three tested SNPs show any association with OGTT-derived parameters of insulin release. In the MR subgroup, SNP rs8046707 was nominally associated with lower visceral adipose tissue. Furthermore, the SNP rs1458201 showed a nominal association with increased VLDL levels. CONCLUSIONS: In conclusion, this study, even though preliminary and awaiting further confirmation by independent replication, provides first evidence that common genetic variation in CTF1 could contribute to insulin sensitivity in humans. Our SNP data indicate an insulin-desensitizing effect of cardiotrophin-1 and underline that cardiotrophin-1 represents an interesting target to influence insulin sensitivity.

  4. 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.

  5. Development of two highly sensitive forensic sex determination assays based on human DYZ1 and Alu repetitive DNA elements.

    Science.gov (United States)

    Fazi, Amanda; Gobeski, Brianne; Foran, David

    2014-11-01

    Sex determination is a critical component of forensic identification, the standard genetic method for which is detection of the single copy amelogenin gene that has differing homologues on the X and Y chromosomes. However, this assay may not be sensitive enough when DNA samples are minute or highly compromised, thus other strategies for sex determination are needed. In the current research, two ultrasensitive sexing assays, based on real-time PCR and pyrosequencing, were developed targeting the highly repetitive elements DYZ1 on the Y chromosome and Alu on the autosomes. The DYZ1/Alu strategy was compared to amelogenin for overall sensitivity based on high molecular weight and degraded DNA, followed by assaying the sex of 34 touch DNA samples and DNA from 30 hair shafts. The real-time DYZ1/Alu assay proved to be approximately 1500 times more sensitive than its amelogenin counterpart based on high molecular weight DNA, and even more sensitive when sexing degraded DNA. The pyrosequencing DYZ1/Alu assay correctly sexed 26 of the touch DNAs, compared to six using amelogenin. Hair shaft DNAs showed equally improved sexing results using the DYZ1/Alu assays. Overall, both DYZ1/Alu assays were far more sensitive and accurate than was the amelogenin assay, and thus show great utility for sexing poor quality and low quantity DNA evidence.

  6. State-of-Science Approaches to Determine Sensitive Taxa for Water Quality Criteria Derivation

    Science.gov (United States)

    Current Ambient Water Quality Criteria (AWQC) guidelines specify pre-defined taxa diversity requirements, which has limited chemical-specific criteria development in the U.S. to less than 100 chemicals. A priori knowledge of sensitive taxa to toxicologically similar groups of che...

  7. Determining the Anxiety Sensitivity Bases of Anxiety: A Study with Undergraduate Students

    Science.gov (United States)

    Erozkan, Atilgan

    2017-01-01

    This study aims to examine the relationships between subdimensions of anxiety sensitivity and anxiety. The participants in the study were 841 undergraduate students (411 females; 430 males) randomly selected from three different faculties--Faculties of Technical Education, Education, and Sport Sciences--at Mugla Sitki Kocman University. Data…

  8. 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 health...

  9. Size determines antennal sensitivity and behavioral threshold to odors in bumblebee workers

    Science.gov (United States)

    Spaethe, Johannes; Brockmann, Axel; Halbig, Christine; Tautz, Jürgen

    2007-09-01

    The eusocial bumblebees exhibit pronounced size variation among workers of the same colony. Differently sized workers engage in different tasks (alloethism); large individuals are found to have a higher probability to leave the colony and search for food, whereas small workers tend to stay inside the nest and attend to nest duties. We investigated the effect of size variation on morphology and physiology of the peripheral olfactory system and the behavioral response thresholds to odors in workers of Bombus terrestris. Number and density of olfactory sensilla on the antennae correlate significantly with worker size. Consistent with these morphological changes, we found that antennal sensitivity to odors increases with body size. Antennae of large individuals show higher electroantennogram responses to a given odor concentration than those of smaller nestmates. This finding indicates that large antennae exhibit an increased capability to catch odor molecules and thus are more sensitive to odors than small antennae. We confirmed this prediction in a dual choice behavioral experiment showing that large workers indeed are able to respond correctly to much lower odor concentrations than small workers. Learning performance in these experiments did not differ between small and large bumblebees. Our results clearly show that, in the social bumblebees, variation in olfactory sensilla number due to size differences among workers strongly affects individual odor sensitivity. We speculate that superior odor sensitivity of large workers has favored size-related division of labor in bumblebee colonies.

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

    OpenAIRE

    Felisberto G. Santos; Boaventura F. Reis

    2017-01-01

    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 sensit...

  11. Stabilizing effects of coenzyme Q10 on potassium ion release, membrane potential and fluidity of rabbit red blood cells.

    Directory of Open Access Journals (Sweden)

    Shinozawa,Shinya

    1980-09-01

    Full Text Available The effects of coenzyme Q10 (Co Q10 on potassium ion release, membrane potential and fluidity of rabbit red blood cells were studied. Co Q10 inhibited the increased potassium ion release induced by cetylamine or lysolecithin from the cells. Co Q10 slightly decreased the membrane potential monitored by changes in fluorescence intensity of cyanine dye, 3,3'-dipropyl-2,2'-thiodicarbocyanine iodide [diS-C3-(5], and also slightly decreased the membrane fluidity measured by using 1,6-diphenyl-1,3,5-hexatriene (DPH. These effects of Co Q10 on the membrane are considered to be due to its membrane stabilizing activity by interaction with lipid bilayers of the membrane.

  12. "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.

  13. Comparative effects of technical toxaphene, 2,5-dichloro-3-biphenylol and octabromodiphenylether on cell viability, [Ca2+]i levels and membrane fluidity in mouse thymocytes.

    Science.gov (United States)

    Sandal, Suleyman; Yilmaz, Bayram; Chen, Chang-Hwei; Carpenter, David O

    2004-08-01

    Flow cytometric studies of mouse thymocytes show that technical toxaphene (10-20 ppm) and 2,5-dichloro-3-biphenylol (PCB 9-OH) (5-10 ppm) kill cells and cause an increase in intracellular calcium concentration, [Ca2+]i, whereas commercial octabromodiphenylether (OBDE) has no effect. The cell death is not a result of the rise of [Ca2+]i, since the divalent cation ionophore, ionomycin, causes a large elevation in [Ca2+]i without cell death. We have studied effects of these compounds on membrane fluorescence polarization, a measure of membrane fluidity, using 1,6-diphenyl-1,3,5-hexatriene (DPH). We find that toxaphene causes a decrease in membrane fluidity in the concentration range associated with cell death, whereas PCB 9-OH causes an increase in fluidity and OBDE has no effect. These observations suggest that alterations of membrane fluidity of thymocytes, whether it be an increase or decrease, can cause cytotoxicity.

  14. 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...... that differences in the acute transcriptional response to insulin are primarily driven by obesity per se, challenging the notion of healthy obese adipose tissue, at least in severe obesity....

  15. 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.

  16. 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.

  17. Notch Sensitivity Factor Determination With Artificial Neural Network For Shafts Under The Bending Stress

    Directory of Open Access Journals (Sweden)

    Murat Tolga Özkan

    2013-01-01

    Full Text Available Notch, hole, tap and a variety of geometric shapes such as curves or discontinuities can be found with various reasons in the design of Machine Element. Stress is caused by sudden changes in section aggregating. Stress concentration can occur with the reason of material features of size or direction of forces application. This type of stress concentration in the material brings out the effect of notch. Notch impact can lead to distortions and breakage of materials. In this study, the notch sensitivity factor values have been modelled Artificial Neural Networks (ANN for shafts that is under the influence of bending stress, and the accuracy of the model has been verified by using Statistica software. The model has been developed using Pythia. With this software, the user can be obtained the accurate value by inputing shaft dimension and the applied force without the need for notch sensitivity factor tables and any calculations.

  18. Determination of flumioxazin residue in food samples through a sensitive fluorescent sensor based on click chemistry.

    Science.gov (United States)

    Lu, Lijun; Yang, Linlin; Cai, Huijian; Zhang, Lan; Lin, Zhenyu; Guo, Longhua; Qiu, Bin; Chen, Guonan

    2014-11-01

    A sensitive and selective fluorescent sensor for flumioxazin was designed based on the formation of strong fluorescence compound (1,2,3-triazole compounds) via the reaction of the alkynyl group in flumioxazin with 3-azido-7-hydroxycoumarin, a weak-fluorescent compound, through the Cu(+)-catalysed azide-alkyne cycloaddition (CuAAC) reaction. The fluorescence increase factor (represented by F/F0) of the system exhibited a good linear relationship with the concentrations of flumioxazin in the range of 0.25-6.0 μg/L with a detection limit of 0.18 μg/L (S/N=3). Also, the proposed fluorescent sensor demonstrated good selectivity for flumioxazin assay even in the presence of high concentration of other pesticides. Based on such high sensitivity and selectivity, the proposed fluorescent sensor has been applied to test the flumioxazin residue in some vegetable and water samples with satisfied results.

  19. Membrane fluidity profiles as deduced by saturation-recovery EPR measurements of spin-lattice relaxation times of spin labels.

    Science.gov (United States)

    Mainali, Laxman; Feix, Jimmy B; Hyde, James S; Subczynski, Witold K

    2011-10-01

    There are no easily obtainable EPR spectral parameters for lipid spin labels that describe profiles of membrane fluidity. The order parameter, which is most often used as a measure of membrane fluidity, describes the amplitude of wobbling motion of alkyl chains relative to the membrane normal and does not contain explicitly time or velocity. Thus, this parameter can be considered as nondynamic. The spin-lattice relaxation rate (T(1)(-1)) obtained from saturation-recovery EPR measurements of lipid spin labels in deoxygenated samples depends primarily on the rotational correlation time of the nitroxide moiety within the lipid bilayer. Thus, T(1)(-1) can be used as a convenient quantitative measure of membrane fluidity that reflects local membrane dynamics. T(1)(-1) profiles obtained for 1-palmitoyl-2-(n-doxylstearoyl)phosphatidylcholine (n-PC) spin labels in dimyristoylphosphatidylcholine (DMPC) membranes with and without 50 mol% cholesterol are presented in parallel with profiles of the rotational diffusion coefficient, R(⊥), obtained from simulation of EPR spectra using Freed's model. These profiles are compared with profiles of the order parameter obtained directly from EPR spectra and with profiles of the order parameter obtained from simulation of EPR spectra. It is shown that T(1)(-1) and R(⊥) profiles reveal changes in membrane fluidity that depend on the motional properties of the lipid alkyl chain. We find that cholesterol has a rigidifying effect only to the depth occupied by the rigid steroid ring structure and a fluidizing effect at deeper locations. These effects cannot be differentiated by profiles of the order parameter. All profiles in this study were obtained at X-band (9.5 GHz).

  20. Formation and fluidity measurement of supported lipid bilayer on polyvinyl chloride membrane

    Science.gov (United States)

    Kobayashi, Takuji; Kono, Akiteru; Futagawa, Masato; Sawada, Kazuaki; Tero, Ryugo

    2014-02-01

    We prepared an artificial lipid bilayer on a plasticized poly(vinyl chloride) (PVC) membrane on a Si3N4 layer deposited on a Si wafer. We optimized the experimental condition for the fabrication of the PVC membrane, and obtained a PVC membrane with a flat and uniform surface on the scale of several hundreds of micrometer suitable for a substrate for supported lipid bilayers (SLBs). The SLB of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) was formed on the PVC membrane by the vesicle fusion method. The observation with a conventional epi-fluorescence microscope and a confocal laser scanning microscope gave geometrically uniform images of the SLB on the PVC membrane. The fluidity and the mobile fraction of the SLB was evaluated by the fluorescence recovery after photobleaching method, and compared with that on a thermally oxidized SiO2/Si substrate. The SLB on the PVC membrane contained immobile fraction ˜30%, but the diffusion in the mobile fraction was two times faster than that in the SLB on SiO2/Si, which had little immobile fraction.

  1. Effect of Holding Time on Thixotropic Fluidity of Semi-solid AZ91D Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    Zesheng JI; Maoliang HU; Xiaoping ZHENG

    2007-01-01

    To investigate the thixotropic fluidities, microstructures and mechanical properties of semi-solid AZ91D magnesium alloy during reheating, a self-made die set with channels of different sizes were used. The results show that critical forming forces and maximal forming forces could be obtained and related to the holding times in the semi-solid forming process. In the holding time of 0-2700 s, with increasing the holding time, maximal forming force decreased sharply and critical forming force decreased slowly. In the whole thixotropic flowing process, the filling-in was steady and the surface fineness was good. The forming force increased when the slurry changed the flowing direction or flowed from the big-diameter chamber to the small-diameter one. The tensile strength and elongation to failure of the sample after holding time for 2700 s, compared to as-cast sample, are increased by approximately 42.7% and 180%, respectively, and the fractured surfaces presented dimple-like pattern.

  2. Formation and fluidity measurement of supported lipid bilayer on polyvinyl chloride membrane

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Takuji, E-mail: kobayashi-t@int.ee.tut.ac.jp; Kono, Akiteru, E-mail: kobayashi-t@int.ee.tut.ac.jp; Sawada, Kazuaki [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka Tempaku-cho, Toyohashi, 441-8580 (Japan); Futagawa, Masato [Department of Electrical and Electronic Information Engineering and Head Office for the Tailor-Made and Baton-Zone Graduate Course, Toyohashi University of Technology, 1-1 Hibarigaoka Tempaku-cho, Toyohashi, 441-8580 (Japan); Tero, Ryugo, E-mail: tero@tut.jp [Electronics-Inspired Interdisciplinary Research Institute and Department of Environmental and Life Sciences, Toyohashi University of Technology, 1-1 Hibarigaoka Tempaku-cho, Toyohashi, 441-8580 (Japan)

    2014-02-20

    We prepared an artificial lipid bilayer on a plasticized poly(vinyl chloride) (PVC) membrane on a Si3N4 layer deposited on a Si wafer. We optimized the experimental condition for the fabrication of the PVC membrane, and obtained a PVC membrane with a flat and uniform surface on the scale of several hundreds of micrometer suitable for a substrate for supported lipid bilayers (SLBs). The SLB of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) was formed on the PVC membrane by the vesicle fusion method. The observation with a conventional epi-fluorescence microscope and a confocal laser scanning microscope gave geometrically uniform images of the SLB on the PVC membrane. The fluidity and the mobile fraction of the SLB was evaluated by the fluorescence recovery after photobleaching method, and compared with that on a thermally oxidized SiO{sub 2}/Si substrate. The SLB on the PVC membrane contained immobile fraction ∼30%, but the diffusion in the mobile fraction was two times faster than that in the SLB on SiO{sub 2}/Si, which had little immobile fraction.

  3. Energy metabolism determines the sensitivity of human hepatocellular carcinoma cells to mitochondrial inhibitors and biguanide drugs.

    Science.gov (United States)

    Hsu, Chia-Chi; Wu, Ling-Chia; Hsia, Cheng-Yuan; Yin, Pen-Hui; Chi, Chin-Wen; Yeh, Tien-Shun; Lee, Hsin-Chen

    2015-09-01

    Human hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide particularly in Asia. Deregulation of cellular energetics was recently included as one of the cancer hallmarks. Compounds that target the mitochondria in cancer cells were proposed to have therapeutic potential. Biguanide drugs which inhibit mitochondrial complex I and repress mTOR signaling are clinically used to treat type 2 diabetes mellitus patients (T2DM) and were recently found to reduce the risk of HCC in T2DM patients. However, whether alteration of energy metabolism is involved in regulating the sensitivity of HCC to biguanide drugs is still unclear. In the present study, we treated four HCC cell lines with mitochondrial inhibitors (rotenone and oligomycin) and biguanide drugs (metformin and phenformin), and found that the HCC cells which had a higher mitochondrial respiration rate were more sensitive to these treatments; whereas the HCC cells which exhibited higher glycolysis were more resistant. When glucose was replaced by galactose in the medium, the altered energy metabolism from glycolysis to mitochondrial respiration in the HCC cells enhanced the cellular sensitivity to mitochondrial inhibitors and biguanides. The energy metabolism change enhanced AMP-activated protein kinase (AMPK) activation, mTOR repression and downregulation of cyclin D1 and Mcl-1 in response to the mitochondrial inhibitors and biguanides. In conclusion, our results suggest that increased mitochondrial oxidative metabolism upregulates the sensitivity of HCC to biguanide drugs. Enhancing the mitochondrial oxidative metabolism in combination with biguanide drugs may be a therapeutic strategy for HCC.

  4. Giardia lamblia allergenic extract as diagnosis procedures for determining sensitization to this protozoa.

    Science.gov (United States)

    Crespo Guerrero, V; Alfonso Fernández, L A; Gómez Echevarría, A H

    1991-12-01

    We studied 200 patients assisting at the Allergy Department and the Gastroenterology Department in "Hermanos Ameijeiras" Clinical-Surgical Hospital. They were clinically and immunologically tested for giardiasis through duodenal fortis or gall bladder drainage and total IgE serum levels. All patients underwent intradermal and skin prick tests with Giardine allergenic extract. These skin tests showed high sensitivity and increased specificity. Thus, our procedure in diagnosis is accurate, accessible and economical.

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

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Jea Myoung; Cho, Myung Sug [KEPCO Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    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

  6. Toxicity of terpenes on fibroblast cells compared to their hemolytic potential and increase in erythrocyte membrane fluidity.

    Science.gov (United States)

    Mendanha, Sebastião A; Moura, Soraia S; Anjos, Jorge L V; Valadares, Marize C; Alonso, Antonio

    2013-02-01

    Terpenes are considered potent skin permeation enhancers with low toxicity. Electron paramagnetic resonance (EPR) spectroscopy of the spin label 5-doxyl stearic acid (5-DSA) was used to monitor the effect of sesquiterpene nerolidol and various monoterpenes on membrane fluidity in erythrocyte and fibroblast cells. In addition, the hemolytic levels and cytotoxic effects on cultured fibroblast cells were also measured to investigate possible relationships between the cellular irritation potentials of terpenes and the ability to modify membrane fluidity. All terpenes increased cell membrane fluidity with no significant differences between the monoterpenes, but the effect of sesquiterpene was significantly greater than that of the monoterpenes. The IC(50) values for the terpenes in the cytotoxicity assay indicated that 1,8-cineole showed lower cytotoxicity and α-terpineol and nerolidol showed higher cytotoxicity. The correlation between the hemolytic effect and the IC(50) values for fibroblast viability was low (R=0.61); however, in both tests, nerolidol was among the most aggressive of terpenes and 1,8-cineole was among the least aggressive. Obtaining information concerning the toxicity and potency of terpenes could aid in the design of topical formulations optimized to facilitate drug absorption for the treatment of many skin diseases.

  7. Sensitive determination of sertraline by capillary electrophoresis with dispersive liquid-liquid microextraction and field-amplified sample stacking.

    Science.gov (United States)

    Huang, Shiou-Wen; Hsieh, Ming-Mu; Chang, Sarah Y

    2012-11-15

    A novel method for the determination of sertraline using dispersive liquid-liquid microextraction (DLLME) coupled with capillary electrophoresis (CE) was developed. Acetone and dichloromethane were used as the disperser solvent and extraction solvent, respectively. A mixture of the extraction and disperser solvents was rapidly injected into a 1.0 mL aqueous sample to form a cloudy solution. After the extraction, sertraline was analyzed using CE that was equipped with UV detection. A 74-fold improvement in the sensitivity was observed when DLLME was used to extract sertraline. Since the DLLME extract residue was redissolved with 5 μL of water that contained 20% methanol, the detection sensitivity was further enhanced through the use of field-amplified sample stacking (FASS). A 11-fold improvement in the sensitivity was obtained when FASS was used to on-line concentrate sertraline. Under optimal extraction and stacking conditions, the calibration curve, which ranged from 0.01 to 1 μM was observed to be linear. The limit of detection (LOD) at a signal-to-noise ratio of 3 was 2.5 nM for sertraline. An approximately 814-fold improvement in the sensitivity was observed for sertraline compare with injection of standard solution without the DLLME and FASS procedures. This developed method was successfully applied to the determination of sertraline in human urine samples.

  8. Identification of the determinants of 2-deoxyglucose sensitivity in cancer cells by shRNA library screening.

    Science.gov (United States)

    Kobayashi, Hiroki; Nishimura, Haruna; Matsumoto, Ken; Yoshida, Minoru

    2015-11-06

    Combining glycolytic inhibition with other anti-cancer therapies is a potential approach to treating cancer. In this context, we attempted to identify genes that determine sensitivity to 2-deoxyglucose (2DG), a glycolytic inhibitor, in cancer cells using pooled shRNA libraries targeting ∼15,000 genes. The screen revealed that COPB1 and ARCN1, which are essential in retrograde transport, as determinants of sensitivity to 2DG: silencing of COPB1 or ARCN1 expression sensitized cells to 2DG toxicity. To address the mechanism of potentiation of 2DG toxicity by inhibition of COPI-mediated transport, we focused on the role of lipolysis as an alternate source of energy upon inhibition of glycolysis. In the process of lipolysis, COPI-mediated transport is required for localization to lipid droplets of adipose triglyceride lipase (ATGL), a key enzyme that produces fatty acids from triacylglycerol as a substrate for β-oxidation. The ATGL inhibitor atglistatin potentiated 2DG toxicity, consistent with a model in which a defect in COPI-mediated transport of ATGL to lipid droplets inhibits energy supply, thereby sensitizing cells to glycolytic inhibition. Collectively, our data demonstrated that a defect in COPI-mediated transport or pharmacological inhibition of ATGL potentiates 2DG toxicity in cancer cells, possibly due to a reduction in the energy supply.

  9. Sensitive determination of specific radioactivity of positron emission tomography radiopharmaceuticals by radio high-performance liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Ryuji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)], E-mail: nakaor@nirs.go.jp; Furutsuka, Kenji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Sumitomo Accelerator Service, Tokyo 141-8686 (Japan); Yamaguchi, Masatoshi [Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka 814-0180 (Japan); Suzuki, Kazutoshi [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)

    2008-10-15

    A sensitive quality control method is often required in positron emission tomography (PET) radiopharmaceutical analysis due to the high specific radioactivity of synthetic products. The applicability of a radio high-performance liquid chromatography (HPLC) method with fluorescence detection was evaluated for a wide variety of PET radiopharmaceuticals. In 29 different radiopharmaceuticals studied, 20 compounds exhibited native fluorescence. These properties enabled sensitive determination of their chemical masses by direct fluorimetric detection after separation by HPLC. For some substances, detection limits were below nanograms per milliliter level, at least 40 times better than current UV absorbance detection. Sufficient reproducibility and linearity were obtained for the analysis of pharmaceutical fluid. Post-column fluorimetric derivatization was also established for the quantitative determination of FDG and ClDG in [{sup 18}F]FDG samples. These methods could be applied successfully to the analysis of PET radiopharmaceuticals with ultra-high specific radioactivity.

  10. Kinetic flow-injection-spectrofluorimetric determination of aluminium(III) using Eriochrome Red B, sensitized by traces of fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo, F. [Universidad Complutense de Madrid (Spain). Dept. de Quimica Analitica; Perez-Conde, C. [Universidad Complutense de Madrid (Spain). Dept. de Quimica Analitica; Camara, C. [Universidad Complutense de Madrid (Spain). Dept. de Quimica Analitica

    1996-01-01

    A flow injection-spectrofluorimetric method is reported for the determination of Al(III) based on the use of Eriochrome Red B and hexamethylenetetramine buffer, sensitized by the presence of fluoride at 80 C. Various chemical and physical variables affecting the reaction in the flow system were evaluated. The method is very sensitive with a detection limit of 0.1 {mu}g 1{sup -1} and a precision at the 5 {mu}g 1{sup -1} level of 2.6%. The calibration range is linear up to 1000 {mu}g 1{sup -1}. The method has been successfully applied to the determination of Al (III) in tap and mineral waters and urine samples. (orig.)

  11. A Simulation Model to Determine Sensitivity and Timeliness of Surveillance Strategies

    DEFF Research Database (Denmark)

    Schulz, Jana; Staubach, C.; Conraths, F. J.

    2016-01-01

    Animal surveillance systems need regular evaluation. We developed an easily applicable simulation model of the German wild boar population to investigate two evaluation attributes: the sensitivity and timeliness (i.e. the ability to detect a disease outbreak rapidly) of a surveillance system...... is therefore vital. Our non-epidemic simulation model is based on real data and evaluates the currently implemented German surveillance system for CSF in wild boar. The results show that active surveillance for CSF fulfils the requirements of detecting an outbreak with 95% confidence within one year after...

  12. Study on New Sensitive Method of Determination of Phosphorus by Solid Phase Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The use of solid phase spectrophotometry for the determination of trace phosphorus in the system of phosphomolybdate-fructose is described. The adsorption of the system on anion-exchange resin is reported.

  13. The quantitative determination of the spectral distribution of phototactic sensitivity in the purple bacterium Rhodospirillum rubrum

    NARCIS (Netherlands)

    Milatz, J.M.W.; Manten, A.

    1953-01-01

    By using a compensation method, the action spectrum (spectral distribution of stimulating efficiency in a quantitative measure) of phototaxis in the purple bacterium Rhodospirillum rubrum (Esmarch) Molisch Strain 4 was determined. Two differently coloured adjacent small light fields were projected

  14. Sensitivity of seismic hazard evaluations to uncertainties determined from seismic source characterization

    Science.gov (United States)

    Tavakoli, Behrooz

    The sensitivity and overall uncertainty in peak ground acceleration (PGA)estimates have been calculated for the city of Tabriz, northwestern Iran byusing a specific randomized blocks design. Eight seismic hazard models andparameters with randomly selected uncertainties at two levels have beenconsidered and then a linear model between predicted PGA at a givenprobability level and the uncertainties has been performed. The inputmodels and parameters are those related to the attenuation, magnituderupture-length and recurrence relationships with their uncertainties.Application of this procedure to the studied area indicates that effects ofthe simultaneous variation of all eight input models and parameters on thesensitivity of the seismic hazard can be investigated with a decreasingnumber of computations for all possible combinations at a fixed annualprobability. The results show that the choice of a mathematical model ofthe source mechanism, attenuation relationships and the definition ofseismic parameters are most critical in estimating the sensitivity of seismichazard evaluation, in particular at low levels of probability of exceedance.The overall uncertainty in the expected PGA for an annual probability of0.0021 (10% exceedence in 50 yr) is expressed by a coefficient ofvariation (CV) of about 34% at 68% confidence level for a distance ofabout 5km from the field of the major faults. The CV will decrease withincreasing site-source distance and remains constant, CV = 15%, fordistances larger than 15 km. Finally, treating alternative models on theoverall uncertainty are investigated by additional outliers in input decision.

  15. 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.

  16. 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.

  17. Complex polarization ratio to determine polarization properties of anisotropic tissue using polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Park, Jesung; Kemp, Nate J; Rylander, H Grady; Milner, Thomas E

    2009-08-03

    Complex polarization ratio (CPR) in materials with birefringence and biattenuance is shown as a logarithmic spiral in the complex plane. A multi-state Levenberg-Marquardt nonlinear fitting algorithm using the CPR trajectory collected by polarization sensitive optical coherence tomography (PS-OCT) was developed to determine polarization properties of an anisotropic scattering medium. The Levenberg-Marquardt nonlinear fitting algorithm using the CPR trajectory is verified using simulated PS-OCT data with speckle noise. Birefringence and biattenuance of a birefringent film, ex-vivo rodent tail tendon and in-vivo primate retinal nerve fiber layer were determined using measured CPR trajectories and the Levenberg-Marquardt nonlinear fitting algorithm.

  18. Critical System Cascading Collapse Assessment for Determining the Sensitive Transmission Lines and Severity of Total Loading Conditions

    Directory of Open Access Journals (Sweden)

    Nur Ashida Salim

    2013-01-01

    Full Text Available This paper presents a computationally accurate technique used to determine the estimated average probability of a system cascading collapse considering the effect of hidden failure on a protection system. This includes an accurate calculation of the probability of hidden failure as it will give significant effect on the results of the estimated average probability of system cascading collapse. The estimated average probability of a system cascading collapse is then used to determine the severe loading condition contributing to a higher risk of a system cascading collapse. This information is important because it will assist the utility to determine the maximum level of increase in the system loading condition before the occurrence of critical power system cascading collapse. Furthermore, the initial tripping of sensitive transmission line contributing to a critical system cascading collapse can also be determined by using the proposed method. Based on the results obtained from this study, it was found that selecting the accurate probability of hidden failure is very important as it will affect the estimated average probability of a system cascading collapse. Comparative study has been done with other techniques to verify the effectiveness of the proposed method used in the determination of sensitive transmission lines.

  19. Novel Analytic Method for Determining Micro-Doppler Measurement Sensitivity in Life-detection Radar

    Directory of Open Access Journals (Sweden)

    Hu Cheng

    2016-10-01

    Full Text Available In recent years, a new non-contact life detecting device has been developed, known as life-detection radar, which can measure bodily movement and locate human subjects. Typically, the amplitude of the vibration being measured is quite small, so the measurement is easily contaminated by noise in the radar system. To date, there is no effective index for judging the influence of noise on the vibration measurements in this radar system. To solve this problem, in this paper, we define the micro-Doppler measurement sensitivity to analyze the influence of noise on the measurement. We then perform a simulation to generate a performance curve for the radar system.

  20. Assessment of the use of temperature-sensitive microchips to determine core body temperature in goats.

    Science.gov (United States)

    Torrao, N A; Hetem, R S; Meyer, L C R; Fick, L G

    2011-03-26

    Body temperature was measured at five different body sites (retroperitoneum, groin, semimembranosus muscle, flank and shoulder) using temperature-sensitive microchips implanted in five female goats, and compared with the core body and rectal temperatures. Body temperature was measured while the goats were kept in different ambient temperatures, with and without radiant heat, as well as during a fever induced experimentally by injection of bacterial lipopolysaccharide. Bland-Altman limit of agreement analysis was used to compare the temperature measurements at the different body sites during the different interventions. Temperatures measured by the microchip implanted in the retroperitoneum showed the closest agreement (mean 0.2 °C lower) with core and rectal temperatures during all interventions, whereas temperatures measured by the microchips implanted in the groin, muscle, flank and shoulder differed from core body temperature by up to 3.5 °C during the various interventions.

  1. Determinants of Obesity in Italian Adults: The Role of Taste Sensitivity, Food Liking, and Food Neophobia.

    Science.gov (United States)

    Proserpio, Cristina; Laureati, Monica; Bertoli, Simona; Battezzati, Alberto; Pagliarini, Ella

    2016-02-01

    Recent evidence has suggested that factors related to sensory perception may explain excess weight. The objective of this study was to consider multiple aspects while investigating the phenomenon of obesity. One goal was to compare taste acuity (taste threshold and density of fungiform papillae) in both normal weight and obese subjects. Thresholds for 4 basic tastes and the fat stimulus were investigated. A second research goal was to study the relationship between food neophobia and food liking according to the body mass index and taste sensitivity. The results showed that obese subjects seem to have higher threshold values and a reduced number of fungiform papillae than do normal weight subjects. Food neophobia did not vary with nutritional status, whereas differences were found for food liking, with obese subjects showing significantly higher liking ratings for high energy dense products compared with normal weight subjects.

  2. Mass-Sensitive Biosensor Systems to Determine the Membrane Interaction of Analytes.

    Science.gov (United States)

    Hoß, Sebastian G; Bendas, Gerd

    2017-01-01

    Biosensors are devices that transform a biological interaction into a readout signal, which is evaluable for analytical purposes. The general strength of biosensor approaches is the avoidance of time-consuming and cost-intensive labeling procedures of the analytes. In this chapter, we give insight into a mass-sensitive surface-acoustic wave (SAW) biosensor, which represents an elegant and highly sensitive method to investigate binding events at a molecular level. The principle of SAW technology is based on the piezoelectric properties of the sensors, so as to binding events and their accompanied mass increase at the sensor surface are detectable by a change in the oscillation of the surface acoustic wave. In combination with model membranes, transferred to the sensor surface, the analytical value of SAW biosensors has strongly been increased and extended to different topics of biomedical investigations, including antibiotic research. The interaction with the bacterial membrane or certain target structures therein is the essential mode of action for various antibacterial compounds. Beside targeted interaction, an unspecific membrane binding or membrane insertion of drugs can contribute to the antibacterial activity by changing the lateral order of membrane constituents or by interfering with the membrane barrier function. Those pleiotropic effects are hardly to illustrate in the bacterial systems and need a detailed view at the in vitro level. Here, we illustrate the usefulness of a SAW biosensor in combination with model membranes to investigate the mode of membrane interaction of antibiotic active peptides. Using two different peptides we exemplary describe the interaction analysis in a two-step gain of information: (1) a binding intensity or affinity by analyzing the phase changes of oscillation, and (2) mode of membrane interaction, i.e., surface binding or internalization of the peptide by following the amplitude of oscillation.

  3. TOPBP1 regulates RAD51 phosphorylation and chromatin loading and determines PARP inhibitor sensitivity

    DEFF Research Database (Denmark)

    Moudry, Pavel; Watanabe, Kenji; Wolanin, Kamila M.

    2016-01-01

    Topoisomerase IIβ-binding protein 1 (TOPBP1) participates in DNA replication and DNA damage response; however, its role in DNA repair and relevance for human cancer remain unclear. Here, through an unbiased small interfering RNA screen, we identified and validated TOPBP1 as a novel determinant wh...

  4. 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...

  5. TOPBP1 regulates RAD51 phosphorylation and chromatin loading and determines PARP inhibitor sensitivity

    DEFF Research Database (Denmark)

    Moudry, Pavel; Watanabe, Kenji; Wolanin, Kamila M.;

    2016-01-01

    Topoisomerase IIβ-binding protein 1 (TOPBP1) participates in DNA replication and DNA damage response; however, its role in DNA repair and relevance for human cancer remain unclear. Here, through an unbiased small interfering RNA screen, we identified and validated TOPBP1 as a novel determinant wh...

  6. A new sensitive tracer for the determination of zooplankton grazing activity

    NARCIS (Netherlands)

    Kwint, R.L J; Kramer, K.J M

    1996-01-01

    A new tracer compound is presented for determining zooplankton grazing activity. The gut content in zooplankton is measured as beta-dimethylsulphoniopropionate (DMSP), which can be measured even in individual copepods. Species specific DMSP/Chl-a ratios allow applications in, for example, prey selec

  7. Noxa determines localization and stability of MCL-1 and consequently ABT-737 sensitivity in small cell lung cancer.

    Science.gov (United States)

    Nakajima, W; Hicks, M A; Tanaka, N; Krystal, G W; Harada, H

    2014-02-13

    The sensitivity to ABT-737, a prototype BH3 mimetic drug, varies in a broad range in small cell lung cancer (SCLC) cells. We have previously shown that the expression of Noxa, a BH3-only pro-apoptotic BCL-2 family protein, is the critical determinant of ABT-737 sensitivity. We show here that Noxa regulates the localization and stability of MCL-1, an anti-apoptotic member, which results in modulating ABT-737 sensitivity. Mutations in Noxa within the BH3 domain, the carboxyl terminus mitochondrial targeting domain, or of ubiquitinated lysines not only change the localization and stability of Noxa itself but also affect the mitochondrial localization and phosphorylation/ubiquitination status of MCL-1 and consequently modulate sensitivity to ABT-737. Results of studies utilizing these mutant proteins indicate that Noxa recruits MCL-1 from the cytosol to the mitochondria. Translocation of MCL-1 initiates its phosphorylation and subsequent ubiquitination, which triggers proteasome-mediated degradation. The precise regulatory mechanisms of Noxa/MCL-1 expression and stability could provide alternative targets to modulate apoptosis induced by BH3 mimetic drugs or other chemotherapeutic reagents.

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

    Science.gov (United States)

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

    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 mgl(-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.

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

    Science.gov (United States)

    Santos, Felisberto G; Reis, Boaventura F

    2017-01-01

    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.

  10. 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.

  11. Determination of Cloud Thermodynamic Phase with Ground Based, Polarimetrically Sensitive, Passive Sky Radiometers

    Science.gov (United States)

    Knobelspiesse, K. D.; van Diedenhoven, B.; Marshak, A.; Dunagan, S. E.; Holben, B. N.; Slutsker, I.

    2015-12-01

    When observed from the ground, optically thick clouds minimally polarize light, while the linear polarization direction (angle) of optically thin clouds contains information about thermodynamic phase. For instruments such at the Cimel radiometers that comprise the AErosol RObotic NEtwork (AERONET), these properties can also be exploited to aid cloud optical property retrievals. Using vector radiative transfer simulations, we explore the conditions most favorable to cloud thermodynamic phase determination, then test with actual AERONET data. Results indicate that this technique may be appropriate for some, but not all, conditions, and motivate a deeper investigation about the polarization direction measurement capability of Cimel instruments, which to date have been primarily used to determine degree of polarization. Recent work explores these measurement issues using a newly installed instrument at the NASA Ames Research Center in Moffett Field, California.

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

    Institute of Scientific and Technical Information of China (English)

    Gui-Ying Jin; Hui Li; Wan-Bang Xu

    2012-01-01

    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.

  13. Determination of diclofenac concentrations in human plasma using a sensitive gas chromatography mass spectrometry method

    OpenAIRE

    2016-01-01

    Background A gas chromatography mass spectrometry (GCMS) method for the determination of diclofenac in human plasma has been developed and validated. Results This method utilizes hexane which is a relatively less toxic extraction solvent compared to heptane and benzene. In addition, phosphoric acid and acetone were added to the samples as deproteination agents, which increased the recovery of diclofenac. These revised processes allow clean extraction and near-quantitative recovery of analyte ...

  14. Determination of diclofenac concentrations in human plasma using a sensitive gas chromatography mass spectrometry method

    OpenAIRE

    Shah, Iltaf; Barker, James; Naughton, Declan P; Barton, Stephen J.; Ashraf, Syed Salman

    2016-01-01

    Background\\ud A gas chromatography mass spectrometry (GCMS) method for the determination of diclofenac in human plasma has been developed and validated.\\ud \\ud Results\\ud This method utilizes hexane which is a relatively less toxic extraction solvent compared to heptane and benzene. In addition, phosphoric acid and acetone were added to the samples as deproteination agents, which increased the recovery of diclofenac. These revised processes allow clean extraction and near-quantitative recover...

  15. Determining contrast sensitivity functions for monochromatic light emitted by high-brightness LEDs

    Science.gov (United States)

    Ramamurthy, Vasudha; Narendran, Nadarajah; Freyssinier, Jean Paul; Raghavan, Ramesh; Boyce, Peter

    2004-01-01

    Light-emitting diode (LED) technology is becoming the choice for many lighting applications that require monochromatic light. However, one potential problem with LED-based lighting systems is uneven luminance patterns. Having a uniform luminance distribution is more important in some applications. One example where LEDs are becoming a viable alternative and luminance uniformity is an important criterion is backlighted monochromatic signage. The question is how much uniformity is required for these applications. Presently, there is no accepted metric that quantifies luminance uniformity. A recent publication proposed a method based on digital image analysis to quantify beam quality of reflectorized halogen lamps. To be able to employ such a technique to analyze colored beams generated by LED systems, it is necessary to have contrast sensitivity functions (CSFs) for monochromatic light produced by LEDs. Several factors including the luminance, visual field size, and spectral power distribution of the light affect the CSFs. Although CSFs exist for a variety of light sources at visual fields ranging from 2 degrees to 20 degrees, CSFs do not exist for red, green, and blue light produced by high-brightness LEDs at 2-degree and 10-degree visual fields and at luminances typical for backlighted signage. Therefore, the goal of the study was to develop a family of CSFs for 2-degree and 10-degree visual fields illuminated by narrow-band LEDs at typical luminances seen in backlighted signs. The details of the experiment and the results are presented in this manuscript.

  16. Electrodeposited apatite coating for solid-phase microextraction and sensitive indirect voltammetric determination of fluoride ions.

    Science.gov (United States)

    Mao, Yuehong; Chen, Yufei; Chu, Lin; Zhang, Xiaoli

    2013-10-15

    Electrodeposition was used to prepare a new solid phase microextraction (SPME) coatings. Two apatite SPME coatings, dicalcium phosphate dihydrate (DCPD or brushite) and hydroxyapatite (HAP) were validly and homogeneously one-step electrodeposited on glassy carbon electrode (GCE) under different conditions. The coatings were characterized by XRD, FTIR, SEM, CV and EIS. The apatite SPME coatings showed excellent and selective adsorbability to fluoride ions. A novel indirect voltammetric strategy for sensitive detection of fluoride was proposed using K3Fe(CN)6 as indicating probe. The detection principle of fluoride ions was based on the increment of steric hindrance after fluoride adsorption, which resulting in the decrease of the amperometric signal to Fe(CN)6(3-). The liner ranges were 0.5-20.0 μmol/L for n-DCPD/GCE with the limit of detection of 0.14 μmol/L and 0.1-50.0 μmol/L for n-HAP/GCE with the limit of detection of 0.069 μmol/L, respectively. The developed method was applied to the analysis of water samples (lake, spring and tap water) and the recovery values were found to be in the range of 90-106%.

  17. 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; Fonseca, Rafael

    2017-02-23

    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.

  18. Sensitive extraction spectrophotometric methods for the determination of trazodone hydrochloride in pure and pharmaceutical formulations

    Directory of Open Access Journals (Sweden)

    K. HARIKRISHNA

    2006-07-01

    Full Text Available Two simple, rapid and sensitive extraction spectrophotometric methods have been developed for the assay of trazodone hydrochloride (TRH in pure and pharmaceutical formulations. These methods are based on the formation of chloroform soluble ion-association complexes of TRH with bromocresol green (BCG and with methyl orange (MO in a KCl–HCl buffer of pH 1.5 (for BCG and in a NaOAc–HCl buffer of pH 3.29 (forMO with absorptionmaximum at 415 nm and at 422 nm for BCG and MO, respectively. The reaction conditions were optimized to obtain the maximum colour intensity. The absorbance was found to increase linearly with increasing concentration of TRH, which was corroborated by the calculated correlation coefficient values (0.9992 and 0.9994. The systems obeyed the Beer law in the range of 0.9–17 and 1–20 mg/ml for BCG and MO, respectively. Various analytical parameters were evaluated and the results were validated by statistical data. No interference was observed from common excipients present in pharmaceutical formulations. The proposed methods are simple, accurate and suitable for quality control applications.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jin; Yang, Beibei; Wang, Huiwen; Yang, Ping; Du, Yukou, E-mail: duyk@suda.edu.cn

    2015-09-17

    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.

  20. The fabrication of CNTs/TiO(2) photoanodes for sensitive determination of organic compounds.

    Science.gov (United States)

    Li, Lihong; Yang, Min; Zhang, Shanqing; Liu, Porun; Li, Guiying; Wen, William; Zhang, Haimin; Zhao, Huijun

    2010-12-03

    Titanium dioxide (TiO(2)) and carbon nanotubes (CNTs) are the two most popular functional materials in recent years. In this study, CNTs/TiO(2) composite and TiO(2) photoanodes were fabricated by a dip-coating technique, followed by subsequent calcination. The resultant photoanodes were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and UV-visible spectroscopy (UV-vis). The results suggest that the carbon nanotubes were successfully incorporated with the TiO(2) nanoparticulates without damage and that the resultant TiO(2) nanoparticles consisted of anatase and rutile. The CNTs/TiO(2) photoanodes were capable of oxidizing various types of organic compounds (e.g. glucose, potassium hydrogen phthalate, and phenol) in aqueous solutions in a photoelectrochemical bulk cell. In comparison with the pure TiO(2) photoanode, the sensitivity of the photoanode for the detection of organic compounds has been improved by 64%, while the background current was reduced by 80% due to the introduction of the CNTs. These advantages can be ascribed to the improved adsorptivity to organic compounds, increased absorption of UV light and enhanced electron transport at the CNTs/TiO(2) photoanode due to the introduction of the CNTs.

  1. Determining water sensitive urban design project benefits using a multi-criteria assessment tool.

    Science.gov (United States)

    Urrutiaguer, M; Lloyd, S; Lamshed, S

    2010-01-01

    The integration of urban water cycle management with urban planning and design is referred to as 'Water Sensitive Urban Design' or 'WSUD' in Australia; one of the key elements of WSUD is the management of urban stormwater. In early 2006, the Victorian Government released the Yarra River Action Plan, which allocated $20 million towards tackling urban stormwater pollution. To help ensure this money is allocated in an equitable and transparent manner across all metropolitan local governments a multi-criteria assessment tool has been developed. This paper presents an overview of the multi-criteria assessment tool developed and adopted for selecting WSUD projects that are eligible for funding through Melbourne Water's Stormwater Program. This tool considers three types of indicators: environmental, engagement (engagement with stakeholders and local government capacity building) and financial. Within each category, a series of indicators of different weightings are applied to score a project. Where initial concept designs do not meet the Program criteria, additional work is undertaken to refine and improve the project. The tool and its use are illustrated with a case study.

  2. Zwitterionic Surfactant Modified Acetylene Black Paste Electrode for Highly Facile and Sensitive Determination of Tetrabromobisphenol A

    Directory of Open Access Journals (Sweden)

    Xiaoyun Wei

    2016-09-01

    Full Text Available A electrochemical sensor for the highly sensitive detection of tetrabromobisphenol A (TBBPA was fabricated based on acetylene black paste electrode (ABPE modified with 3-(N,N-Dimethylpalmitylammonio propanesulfonate (SB3-16 in this study. The peak current of TBBPA was significantly enhanced at SB3-16/ABPE compared with unmodified electrodes. To further improve the electrochemical performance of the modified electrode, corresponding experimental parameters such as the length of hydrophobic chains of zwitterionic surfactant, the concentration of SB3-16, pH value, and accumulation time were examined. The peak currents of TBBPA were found to be linearly correlated with its concentrations in the range of 1 nM to 1 µM, with a detection limit of 0.4 nM. Besides, a possible mechanism was also discussed, and the hydrophobic interaction between TBBPA and the surfactants was suggested to take a leading role in enhancing the responses. Finally, this sensor was successfully employed to detect TBBPA in water samples.

  3. MIC versus MBEC to determine the antibiotic sensitivity of Staphylococcus aureus in peritoneal dialysis peritonitis.

    Science.gov (United States)

    Girard, Louis P; Ceri, Howard; Gibb, Allan P; Olson, Merle; Sepandj, Farshad

    2010-01-01

    Peritoneal dialysis (PD)-related peritonitis is a common and morbid complication of PD. Bacteria are able to create a biofilm on the PD catheter, which can be a source of recurrent infection. Biofilms undergo a phenotypic change resulting in increased antibiotic resistance. ♢ 21 clinical isolates of different patients with PD peritonitis secondary to Staphylococcus aureus were collected. They were analyzed for their antibiotic susceptibility in the planktonic form using the standard minimum inhibitory concentration (MIC) and in a biofilm using minimum biofilm eradication concentration (MBEC). Chi-square was used to compare the sensitivity results. ♢ The isolates were susceptible to all the antibiotics tested using MIC. Every antibiotic except gentamicin lost its efficacy when the bacteria were grown in a biofilm (p > 0.05). The change in susceptibility was statistically significant to a level of p < 0.001 for all antibiotics tested. ♢ In PD peritonitis that is long standing, recurrent, or not responsive to therapy, MBEC testing should be considered as a biofilm may be present. Gentamicin should be strongly considered over other agents for empiric gram-negative coverage as it may be providing synergy in the setting of Staphylococcus aureus. Also, the newer anti-staphylococcal drugs should be tested for their performance in a biofilm using the MBEC method.

  4. Zwitterionic Surfactant Modified Acetylene Black Paste Electrode for Highly Facile and Sensitive Determination of Tetrabromobisphenol A

    Science.gov (United States)

    Wei, Xiaoyun; Zhao, Qiang; Wu, Weixiang; Zhou, Tong; Jiang, Shunli; Tong, Yeqing; Lu, Qing

    2016-01-01

    A electrochemical sensor for the highly sensitive detection of tetrabromobisphenol A (TBBPA) was fabricated based on acetylene black paste electrode (ABPE) modified with 3-(N,N-Dimethylpalmitylammonio) propanesulfonate (SB3-16) in this study. The peak current of TBBPA was significantly enhanced at SB3-16/ABPE compared with unmodified electrodes. To further improve the electrochemical performance of the modified electrode, corresponding experimental parameters such as the length of hydrophobic chains of zwitterionic surfactant, the concentration of SB3-16, pH value, and accumulation time were examined. The peak currents of TBBPA were found to be linearly correlated with its concentrations in the range of 1 nM to 1 µM, with a detection limit of 0.4 nM. Besides, a possible mechanism was also discussed, and the hydrophobic interaction between TBBPA and the surfactants was suggested to take a leading role in enhancing the responses. Finally, this sensor was successfully employed to detect TBBPA in water samples. PMID:27657078

  5. 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.

  6. Highly sensitive determination of copper in HeLa cell using capillary electrophoresis combined with a simple cell extraction treatment.

    Science.gov (United States)

    Meng, Lingchen; Fang, Ziyuan; Lin, Jian; Li, Meixian; Zhu, Zhiwei

    2014-04-01

    A new separation system of capillary electrophoresis (CE1) for the highly sensitive determination of copper was established by using ethylenediaminetetraacetic acid (EDTA) as a complexing agent and employing cetyltrimethylammonium chloride (CTAC) as a capillary inner wall modifier. Benefitted from the combination of field-enhanced sample injection (FESI) method, a limit of detection (LOD) of 2.7 nM was obtained, which was much lower than that of the conventional methods. This made it possible to determine trace copper in HeLa cell only by a simple cell extraction (CE2) treatment. Two copper-extraction methods-acid-hydrolysis and freeze-thaw-were compared. Limited by the requirement of low ion strength in FESI, only the extract using freeze-thaw could be successfully applied in the determination. The effectiveness assessment of this CE(2)-FESI method was adopted by inductively coupled plasma-atomic emission spectrometry (ICP-AES) as a gold standard.

  7. Boronic acid functionalized N-doped carbon quantum dots as fluorescent probe for selective and sensitive glucose determination

    Science.gov (United States)

    Jiang, Guohua; Jiang, Tengteng; Li, Xia; Wei, Zheng; Du, Xiangxiang; Wang, Xiaohong

    2014-04-01

    Nitrogen doped carbon quantum dots (NCQDs) of about 10 nm in diameter have been obtained by hydrothermal reaction from collagen. Because of the superiority of water dispersion, low toxicity and ease of functionlization, the NCQDs were designed as a glucose sensor after covalent grafting by 3-aminophenylboronic (APBA) (APBA-NCQDs). The as-prepared APBA-NCQDs were imparted with glucose sensitivity and selectivity from other saccharides via fluorescence (FL) quenching effect at physiological pH and at room temperature, which show high sensitivity and specificity for glucose determination with a wide range from 1 mM to 14 mM. FL quenching mechanism of APBA-NCQDs was also investigated by adding an external quencher. The APBA-NCQDs-based platform is an environmentally friendly way to substitute inorganic quantum dots containing heavy metals which offer a facile and low cost detection method.

  8. A highly sensitive quantitative real-time pcr assay for determination of mutant jak2 exon 12 allele burden

    DEFF Research Database (Denmark)

    Kjær, L.; Riley, C.H.; Westman, M.

    2012-01-01

    present a highly sensitive real-time quantitative PCR assay for determination of the mutant allele burden of JAK2 exon 12 mutations. In combination with high resolution melting analysis and sequencing the assay identified six patients carrying previously described JAK2 exon 12 mutations and one novel...... mutation. Two patients were homozygous with a high mutant allele burden, whereas one of the heterozygous patients had a very low mutant allele burden. The allele burden in the peripheral blood resembled that of the bone marrow, except for the patient with low allele burden. Myeloid and lymphoid cell...... populations were isolated by cell sorting and quantitative PCR revealed similar mutant allele burdens in CD16+ granulocytes and peripheral blood. The mutations were also detected in B-lymphocytes in half of the patients at a low allele burden. In conclusion, our highly sensitive assay provides an important...

  9. 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......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 preference shifts, technological relative price trends and errors in sectoral data. We find that the elasticity of the input of the distribution sector in transforming imports from domestic consumption reliably indicates complementarity, implying that rigidities in this sector matter in determining...

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

    Science.gov (United States)

    Yaman, Yesim Tugce; Abaci, Serdar

    2016-05-25

    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.

  11. A sensitive LC-MS/MS method for simultaneous determination of amygdalin and paeoniflorin in human plasma and its application.

    Science.gov (United States)

    Li, Xiaobing; Shi, Fuguo; Gu, Pan; Liu, Lingye; He, Hua; Ding, Li

    2014-04-01

    A simple and sensitive HPLC-MS/MS method was developed and fully validated for the simultaneous determination of amygdalin (AD) and paeoniflorin (PF) in human plasma. For both analytes, the method exhibited high sensitivity (LLOQs of 0.6ng/mL) by selecting the ammonium adduct ions ([M+NH4](+)) as the precursor ions and good linearity over the concentration range of 0.6-2000ng/mL with the correlation coefficients>0.9972. The intra- and inter-day precision was lower than 10% in relation to relative standard deviation, while accuracy was within ±2.3% in terms of relative error for both analytes. The developed method was successfully applied to a pilot pharmacokinetic study of AD and PF in healthy volunteers after intravenous infusion administration of Huoxue-Tongluo lyophilized powder for injection. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Sensitive determination of xylenes in whole blood by capillary gas chromatography with cryogenic trapping.

    Science.gov (United States)

    Hattori, H; Iwai, M; Kurono, S; Yamada, T; Watanabe-Suzuki, K; Ishii, A; Seno, H; Suzuki, O

    1998-11-06

    A new and sensitive method for measurement of o-, m- and p-xylenes in human whole blood by capillary gas chromatography (GC) with cryogenic trapping is presented. After heating 0.5 ml of whole blood and 0.5 ml of distilled water containing the xylenes and aniline (internal standard, I.S.) in a 4.0-ml vial at 100 degrees C for 30 min, 2 ml of the headspace vapor was drawn into a glass syringe. All vapor was introduced through the GC port into an AT-Wax middle-bore capillary column in the splitless mode at an oven temperature of 5 degrees C to trap the entire analytes, and the oven temperature was then programmed up to 180 degrees C. The present conditions gave sharp peaks for xylenes and aniline (I.S.), and low background noises for whole blood samples; the peaks of p- and m-xylenes showed about 90% separation with the AT-Wax column. As much as 41.0-46.3% of xylenes, which had been spiked to whole blood could be recovered. The calibration curves showed linearity in the range of 0.1-0.5 microg/0.5 ml of whole blood. The detection limit was estimated to be about 10 ng/0.5 ml. The coefficients of intra-day and inter-day variations for xylenes were not greater than 9.38%. The data for actual detection of xylenes in post-mortem blood of self-ignition suicide cases by the present method were also presented.

  13. 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

    2017-01-01

    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.

  14. Amplified impedimetric immunosensor based on instant catalyst for sensitive determination of ochratoxin A.

    Science.gov (United States)

    Tang, Juan; Huang, Yapei; Zhang, Cengceng; Liu, Huiqiong; Tang, Dianping

    2016-12-15

    A new impedimetric immunosensor for the fast determination of ochratoxin A (OTA) in food samples was developed based on the instant catalyst as enhancer. Initially, the signal tags were prepared via co-immobilization of anti-OTA antibody and amine-terminated dendrimer (PAMAM) on the graphene oxide nanosheets through the covalent interaction, which were utilized as a good platform for combining manganese ion (anti-OTA-GO-PAMAM-Mn(2+)). Upon target OTA introduction, a competitive-type immunoreaction was implemented between the analyte and the immobilized OTA-BSA on the electrode for the anti-OTA antibody on the graphene oxide nanosheets labels. After a competitive immunoassay format, the anti-OTA-GO-PAMAM-Mn(2+) were captured onto the electrode surface, which could induce the in situ formation of MnO2via classical redox reaction between Mn(2+) and KMnO4 on the immunesensing platform. Moreover, the generated MnO2 nanoparticles act as efficient catalyst could catalyze the 4-chloro-1-naphthol (4-CN) oxidation without H2O2 to generate an insoluble precipitation on the platform. Under the optimal conditions, the instant catalyst based impedimetric immunosensor displayed a wide dynamic working range between 0.1pgmL(-1) and 30ngmL(-1). The detection limit (LOD) of the assay was 0.055pgmL(-1). The developed method exhibited high selectivity and can be used for the determination of OTA in real red wine samples.

  15. Highly sensitive fluorescence optode based on polymer inclusion membranes for determination of Al(III) ions.

    Science.gov (United States)

    Suah, F B M; Ahmad, M; Heng, L Y

    2014-07-01

    This paper reports the use of a polymer inclusion membranes (PIMs) for direct determination of Al(III) ions in natural water by using a fluorescence based optode. The best composition of the PIMs consisted of 60 wt.% (m/m) poly (vinyl chloride) (PVC) as the base polymer, 20 wt.% (m/m) triton X-100 as an extractant, 20 wt.% (m/m) dioctyl phthalate (DOP) as plasticizer and morin as the reagent, was used in this study. The inclusion of triton X-100 was used for enhancing the sorption of Al(III) ions from liquid phase into the membrane phase, thus increasing the optode fluorescence intensity. The optimized optode was characterized by a linear calibration curve in the range from 7.41 × 10(-7) to 1.00 × 10(-4) molL(-1) of Al(III), with a detection limit of 5.19 × 10(-7) molL(-1). The response of the optode was 4 min and reproducible results were obtained for eight different membranes demonstrated good membrane stability. The optode was applied to the determination of Al(III) in natural water samples. The result obtained is comparable to atomic absorption spectrometry method.

  16. 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.

  17. 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.

  18. A Validated High-Throughput Fluorometric Method for Determination of Omeprazole in Quality Control Laboratory via Charge Transfer Sensitized Fluorescence.

    Science.gov (United States)

    Mahmoud, Ashraf M; Ahmed, Sameh A

    2016-03-01

    A high-throughput 96-microwell plate fluorometric method was developed and validated to determine omeprazole (OMZ) in its dosage forms. The method was based on the charge-transfer (CT) sensitized fluorescence reaction of OMZ with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ). This fluorescence reaction provided a new approach for simple, sensitive and selective determinations of OMZ in pharmaceutical preparations. In the present method, the fluorescence reaction was carried out in 96-microwell plates as reaction vessels in order to increase the automation of the methodology and the efficiency of its use in quality control laboratories. All factors affecting the fluorescence reaction were carefully studied and the conditions were optimized. The stoichiometry of the fluorescence reaction between OMZ and DDQ was determined and the reaction mechanism was suggested. Under the optimum conditions, the linear range was 100-6000 ng/ml with the lowest LOD of 33 ng/ml. Analytical performance of the proposed assay, in terms of accuracy and precision, was statistically validated and the results were satisfactory; RSD was <2.6 % and the accuracy was 98.6-101.6 %. The method was successfully applied to the analysis of OMZ in its dosage forms; the recovery values were 98.26-99.60 ± 0.95-2.22 %. The developed methodology may provide a safer, automated and economic tool for the analysis of OMZ in quality control laboratories.

  19. A rapid electrochemical monitoring platform for sensitive determination of thiamethoxam based on β-cyclodextrin-graphene composite.

    Science.gov (United States)

    Zhai, XingChen; Zhang, Hua; Zhang, Min; Yang, Xin; Gu, Cheng; Zhou, GuoPeng; Zhao, HaiTian; Wang, ZhenYu; Dong, AiJun; Wang, Jing

    2017-01-20

    A rapid monitoring platform for sensitive voltammetric detection of thiamethoxam residues is reported in the present study. A β-cyclodextrin-reduced graphene oxide composite was used as a reinforcing material in electrochemical determination of thiamethoxam. Compared with bare glassy carbon electrodes, the reduction peak currents of thiamethoxam at reduced graphene oxide/glassy carbon electrode and β-cyclodextrin-reduced graphene oxide/glassy carbon electrode were increased by 70- and 124-fold, respectively. The experimental conditions influencing voltammetric determination of thiamethoxam, such as the amount of β-cyclodextrin-reduced graphene oxide, solution pH, temperature, and accumulation time, were optimized. The reduction mechanism and binding affinity of this material is also discussed. Under optimal conditions, the reduction peak currents increased linearly between 0.5 µM and 16 µM concentration of thiamethoxam. The limit of detection was 0.27 µM on the basis of a signal-to-noise ratio of 3. When the proposed method was applied to brown rice in a recovery test, the recoveries were between 92.20% and 113.75%. The results were in good concordance with the high-performance liquid chromatography method. The proposed method therefore provides a promising and effective platform for sensitive and rapid determination of thiamethoxam. Environ Toxicol Chem 2017;9999:1-7. © 2017 SETAC.

  20. 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.

  1. A reactive and sensitive diffusion sampler for the determination of aldehydes and ketones in ambient air

    Science.gov (United States)

    Uchiyama, Shigehisa; Hasegawa, Shuji

    We developed a diffusive sampling device (DSD-carbonyl) for organic carbonyl compounds (aldehydes and ketones) which is suitable for collection and analysis of low concentration levels. This sampling device is composed of three parts, an exposure part made of a porous polytetrafluoroethylene (PPTFE) tube, an analysis part made of polypropylene (PP) tubing and an absorbent part made of 2,4-dinitrophenylhydrazine (DNPH) coated silica gel (DNPH-silica). Aldehydes and ketones diffuse to the DSD-carbonyl through PPTFE-tube by the mechanism of molecular diffusion and react specifically with DNPH to form a stable DNPH-derivatives. Collection is controlled by moving the absorbent from the exposure part to the analysis part by changing the posture of the DSD-carbonyl. DNPH-derivatives were eluted from an analysis part of DSD-carbonyl with acetonitrile directly and analyzed by high performance liquid chromatography (HPLC). The advantages of the DSD-carbonyl are the following: (1) The DSD-carbonyl can be used in a wide range of concentration of aldehydes and ketones in atmosphere, as the DSD-carbonyl exposure part has a variable diffusion area, (2) DNPH-derivatives are eluted from DNPH-silica without contamination of air. (3) The sampler can be applied to active sampling by connecting it with a pump. The limit of detection (LOD) for concentrations of major aldehydes and ketones ranged from 0.072 to 0.13 ppb, and the limit of quantitation (LOQ) ranged from 0.24 to 0.42 ppb. The coefficient variation (CV) for concentrations of major aldehydes and ketones ranged from 2.5 to 3.0% in laboratory air. The DSD-carbonyl method and active sampling method (US EPA method IP-6A) showed a good correlation (formaldehyde, r2=0.995). The uptake rates for formaldehyde, acetaldehyde, and acetone were estimated as 0.078, 0.062 and 0.079 nmol ppb -1 h -1, respectively. It is possible to estimate atmospheric aldehydes and ketones at parts per billion (ppb), with high sensitivity and precision, by

  2. Direction sensitive laser velocimeter. [determining the direction of particles using a helium-neon laser

    Science.gov (United States)

    Franke, J. M. (Inventor)

    1981-01-01

    A laser velocimeter is described which determines the direction of movement of particles. A laser produces a transmitted beam that illuminates the volume under investigation. The backscattered light is divided into two equal intensity beams. A first part of a sample of the transmitted beam is mixed with one of the two equal intensity beams and applied to a first photodetector. A second part of the sample is phase shifted by 90 deg, mixed with the other of the two equal intensity beams and applied to a second photodetector. The output of the first photodetector is phase shifted by 90 deg and then multiplied with the output of the second photodetector to produce a signal indicative of direction of movement.

  3. Mutational landscape determines sensitivity to PD-1 blockade in non–small cell lung cancer

    Science.gov (United States)

    Rizvi, Naiyer A.; Hellmann, Matthew D.; Snyder, Alexandra; Kvistborg, Pia; Makarov, Vladimir; Havel, Jonathan J.; Lee, William; Yuan, Jianda; Wong, Phillip; Ho, Teresa S.; Miller, Martin L.; Rekhtman, Natasha; Moreira, Andre L.; Ibrahim, Fawzia; Bruggeman, Cameron; Gasmi, Billel; Zappasodi, Roberta; Maeda, Yuka; Sander, Chris; Garon, Edward B.; Merghoub, Taha; Wolchok, Jedd D.; Schumacher, Ton N.; Chan, Timothy A.

    2016-01-01

    Immune checkpoint inhibitors, which unleash a patient’s own T cells to kill tumors, are revolutionizing cancer treatment. To unravel the genomic determinants of response to this therapy, we used whole-exome sequencing of non–small cell lung cancers treated with pembrolizumab, an antibody targeting programmed cell death-1 (PD-1). In two independent cohorts, higher nonsynonymous mutation burden in tumors was associated with improved objective response, durable clinical benefit, and progression-free survival. Efficacy also correlated with the molecular smoking signature, higher neoantigen burden, and DNA repair pathway mutations; each factor was also associated with mutation burden. In one responder, neoantigen-specific CD8+ T cell responses paralleled tumor regression, suggesting that anti–PD-1 therapy enhances neoantigen-specific T cell reactivity. Our results suggest that the genomic landscape of lung cancers shapes response to anti–PD-1 therapy. PMID:25765070

  4. Determination of L-phenylalanine by cucurbit[7]uril sensitized fluorescence quenching method

    Institute of Scientific and Technical Information of China (English)

    Chang Feng Li; Li Ming Du; Hao Wu; Ying Xia Chang

    2011-01-01

    The determination method of L-phenylalanine (LPA) by fluorescence quenching was developed. The assay was based on the combination of the cucurbit[7]uril (CB[7]) with palmatine hydrochloride (PAL) reaction. In the presence of CB[7], the fluorescence of PAL was quenched by LPA which can be employed to detect LPA. Under the optimal conditions, a linear range 3.63 × 10-8-9.68 × 10-6 mol/L and a detection limit 1.27 × 10-8 mol/L of LPA were obtained. The relative standard deviation (R.S.D) was 1.8% obtained from a series of11 standards each containing 6.05 × 10-6 mol/L oLPA. This paper also discusses the mechanism of fluorescence indicator probe.

  5. Determination of vis and NIR quantum yields of Nd{sup 3+}-activated garnets sensitized by Ce{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Möller, S.; Hoffmann, A.; Knaut, D.; Flottmann, J.; Jüstel, T., E-mail: tj@fh-muenster.de

    2015-02-15

    One of the most important quantities to describe the efficiency of luminescent materials is the external photoluminescence quantum yield (ePLQY) which is defined as the ratio of emitted to absorbed photons and thus describes the conversion efficiency of a given phosphor. In optical spectroscopy two methods of determination are applied: The absolute measurement conducted in an integrating sphere and a relative measurement based on a reference material with a known quantum yield. So far both methods are only described for phosphors in the UV and visible range of the electromagnetic spectrum. By using Nd{sup 3+} sensitized and Ce{sup 3+} activated garnets with the general formula (Y,Lu){sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+},Nd{sup 3+} ((Y,Lu)AG:Ce,Nd) we developed a method for the determination of the quantum yield in the near-infrared region. Therefore samples of different compositions have been synthesized and spectroscopically characterized. Starting point of the determination of the overall quantum yield is the determination of the quantum yield of the Ce{sup 3+} emission in the visible range by well-established methods. For using the proportionality of emission integral to the quantum yield it is necessary to scale and combine the measured spectra (460–1000 nm on the vis detector, and 900–1500 nm on the NIR detector). Furthermore, the accuracy of the method was evaluated not only by statistic calculations comprising the propagation of uncertainty but also by using branching ratio data of Nd{sup 3+} given in literature to check the generated overall emission spectra. - Highlights: • Method for determining the external quantum efficiency in the NIR range. • Sensitization and dopant ratio optimization of (Y,Lu)AG:Nd{sup 3+} by Ce{sup 3+}. • Application of branching ratios for evaluation of experimental ePLQY.

  6. Boron-doped diamond film electrode as a sensitive and selective electrochemical sensor for the determination of paracetamol

    OpenAIRE

    Švorc, Ľubomír; Sochr, Jozef; Rievaj, Miroslav; Bustin, Dušan

    2012-01-01

    A simple, sensitive and selective differential pulse voltammetry method for determination of paracetamol on a bare (unmodified) boron-doped diamond film electrode has been developed. It was found by cyclic voltammetry that paracetamol provided the quasireversible wave with oxidation peak on the forward scan about +0.90 V and smaller reduction peak on the reverse scan at +0.68 V vs. Ag/AgCl. The effect of supporting electrolyte, pH and scan rate on voltammetric response of paracetamol was stud...

  7. 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

    of preference shifts, technological relative price trends and errors in sectoral data. We find that the elasticity of the input of the distribution sector in transforming imports from domestic consumption reliably indicates complementarity, implying that rigidities in this sector matter in determining......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...

  8. 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

  9. 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

  10. Eicosapentaenoic acid reduces membrane fluidity, inhibits cholesterol domain formation, and normalizes bilayer width in atherosclerotic-like model membranes.

    Science.gov (United States)

    Mason, R Preston; Jacob, Robert F; Shrivastava, Sandeep; Sherratt, Samuel C R; Chattopadhyay, Amitabha

    2016-12-01

    Cholesterol crystalline domains characterize atherosclerotic membranes, altering vascular signaling and function. Omega-3 fatty acids reduce membrane lipid peroxidation and subsequent cholesterol domain formation. We evaluated non-peroxidation-mediated effects of eicosapentaenoic acid (EPA), other TG-lowering agents, docosahexaenoic acid (DHA), and other long-chain fatty acids on membrane fluidity, bilayer width, and cholesterol domain formation in model membranes. In membranes prepared at 1.5:1 cholesterol-to-phospholipid (C/P) mole ratio (creating pre-existing domains), EPA, glycyrrhizin, arachidonic acid, and alpha linolenic acid promoted the greatest reductions in cholesterol domains (by 65.5%, 54.9%, 46.8%, and 45.2%, respectively) compared to controls; other treatments had modest effects. EPA effects on cholesterol domain formation were dose-dependent. In membranes with 1:1 C/P (predisposing domain formation), DHA, but not EPA, dose-dependently increased membrane fluidity. DHA also induced cholesterol domain formation without affecting temperature-induced changes in-bilayer unit cell periodicity relative to controls (d-space; 57Å-55Å over 15-30°C). Together, these data suggest simultaneous formation of distinct cholesterol-rich ordered domains and cholesterol-poor disordered domains in the presence of DHA. By contrast, EPA had no effect on cholesterol domain formation and produced larger d-space values relative to controls (60Å-57Å; pmembrane bilayer width, membrane fluidity, and cholesterol crystalline domain formation; suggesting omega-3 fatty acids with differing chain length or unsaturation may differentially influence membrane lipid dynamics and structural organization as a result of distinct phospholipid/sterol interactions.

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

    Science.gov (United States)

    Liang, Jintao; Guan, Mingyuan; Huang, Guoyin; Qiu, Hengming; Chen, Zhengcheng; Li, Guiyin; Huang, Yong

    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)=0.00714ChIgG (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.

  12. Improved sensitivity gas chromatography-mass spectrometry determination of parabens in waters using ionic liquids.

    Science.gov (United States)

    Cacho, Juan Ignacio; Campillo, Natalia; Viñas, Pilar; Hernández-Córdoba, Manuel

    2016-01-01

    A new procedure for the introduction of ionic liquid samples in gas chromatography (GC) is proposed. This procedure, based on microvial insert thermal desorption, allows the direct analysis of the compounds preconcentrated by ionic liquid based liquid-liquid microextraction (IL-LLME) using the combination of a thermal desorption unit (TDU) and a programmed temperature vaporization injector (PTV). Two different IL-LLME methodologies, one based on the formation of a microdroplet emulsion by dispersive liquid-liquid microextraction (DLLME) and other through ultrasound-assisted emulsification microextraction (USAEME) were studied and evaluated. IL-DLLME proved advantageous and consequently, it was adopted for preconcentration purposes. This easy to apply approach was used for the determination of five parabens (methyl-, ethyl-, propyl-, butyl- and isobutyl paraben) in swimming pool waters, after in situ acetylation. The optimized conditions of TDU/PTV allowed the analytes contained in 20 µL of the enriched IL to be transferred to the capillary column. Quantification of the samples was carried out against aqueous standards, and quantification limits of between 4.3 and 8.1 ng L(-1) were obtained, depending on the compound. Concentrations of between 9 and 47 ng L(-1) for some analytes were obtained in the analysis of ten samples.

  13. Improving sensitivity in simultaneous determination of copper carboxylates by nonaqueous capillary electrophoresis.

    Science.gov (United States)

    Laamanen, Pirkko-Leena; Blanco, Eva; Cela, Rafael; Matilainen, Rose

    2006-03-31

    A new method of nonaqueous capillary electrophoresis (NACE) with UV spectrophotometric detection was developed and optimized for the simultaneous determination of seven carboxylates (trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), nitrilotriacetic acid (NTA), 1,3-diaminopropane-N,N,N',N'-tetraacetic acid (PDTA) and triethylenetetraaminehexaacetic acid (TTHA)) as copper complexes. The method development was carried out by using a fused silica capillary. Background electrolyte (BGE) was optimized and the best separation achieved by using 30mmolL(-1) potassium bromide in N-methylformamide (NMF) at apparent pH (pH(app)) 10.2. A voltage of +30kV and direct UV detection at 280nm were used in all measurements. Large-volume sample stacking using the electroosmotic flow pump (LVSEP) was tested in addition to basic capillary electrophoresis (CE) and observed to improve the separation of the analyte zones in the capillary. All the peaks in the electropherograms were properly separated, the calibration plots gave excellent correlation coefficients (R(2)>or=0.994) and all seven copper carboxylate complexes were detected in less than 20min using both the basic measurements and the large-volume sample stacking method. The new NACE method was tested with lake water and proved to be reliable.

  14. 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.

  15. Ion imprinted polymeric nanoparticles for selective separation and sensitive determination of zinc ions in different matrices.

    Science.gov (United States)

    Shamsipur, Mojtaba; Rajabi, Hamid Reza; Pourmortazavi, Seied Mahdi; Roushani, Mahmoud

    2014-01-01

    Preparation of Zn(2+) ion-imprinted polymer (Zn-IIP) nanoparticles is presented in this report. The Zn-IIP nanoparticles are prepared by dissolving stoichiometric amounts of zinc nitrate and selected chelating ligand, 3,5,7,20,40-pentahydroxyflavone, in 15 mL ethanol-acetonitrile (2:1; v/v) mixture as a porogen solvent in the presence of ethylene glycol-dimethacrylate (EGDMA) as cross-linking, methacrylic acid (MAA) as functional monomer, and 2,2-azobisisobutyronitrile (AIBN) as initiator. After polymerization, Cavities in the polymer particles corresponding to the Zn(2+) ions were created by leaching the polymer in HCl aqueous solution. The synthesized IIPs were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermal analysis techniques. Also, the pH range for rebinding of Zn(2+) ion on the IIP and equilibrium binding time were optimized, using flame atomic absorption spectrometry. In selectivity study, it was found that imprinting results increased affinity of the material toward Zn(2+) ion over other competitor metal ions with the same charge and close ionic radius. The prepared IIPs were repeatedly used and regenerated for six times without any significant decrease in polymer binding affinities. Finally, the prepared sorbent was successfully applied to the selective recognition and determination of zinc ion in different real samples.

  16. SIMPLE AND SENSITIVE METHOD FOR DETERMINATION OF POLYHEXANIDE IN MULTIPURPOSE SOLUTION

    Directory of Open Access Journals (Sweden)

    M. T. Zzaman

    2009-01-01

    Full Text Available A simple reversed phase HPLC method has been developed for the determination of polyhexamethylene biguanide hydrochloride in multipurpose solution for hydrophilic contact lenses. The mobile phase was acetonitrile 1% (v/v ammonium acetate 20 mM in water as 16: 84 (v/v at a flow rate of 1 ml / min. Polyhexamethylene biguanide hydrochloride was detected by UV absorption at 235 nm. The pH was kept at 4.0 using glacial acetic acid. The method of Yiping et al has been slightly modified as needed. The quantity detected was 2 µg/ml so it was carried out using a preconcentration method under vaccum. From the chromatogram, it was observed that a distinct peak appeared at retention time 5.883 min for polyhexamethylene biguanide hydrochloride. The recovery of drug was found to be 99.38% and the method was simple, rapid and suitable for the assay of drug in multipurpose solution for hydrophilic contact lenses and for carrying out stability as per ICH guidelines to assess the stability of polyhexamethylene biguanide hydrochloride in multipurpose solution.

  17. Human bone marrow cell culture: a sensitive method for determination of the biocompatibility of implant materials.

    Science.gov (United States)

    Wilke, A; Landgraff, M; Orth, J; Poenitz, H; Kienapfel, H; Boelte, K; Griss, P; Franke, R P

    1999-01-01

    The objective of this study was to develop a test method for determining the cytotoxicity and biocompatibility of various biomaterials that are used in orthopaedic surgery. This method is based on the use of a human bone marrow cell culture and was developed as an alternative to animal experiments. Human bone marrow cell culture has certain advantages over other cell culture models, as its results show a greater conformity with animal experimental results and clinical studies. Primary cell adherence, cell number, cell proliferation, production of extracellular matrix, cell viability and cell differentiation were used as indicative parameters of biocompatibility. After 2 weeks in culture, differences could be observed between the biomaterials with respect to these parameters. Cell numbers were greatest on the hydroxyapatite ceramic specimens, but were decreased on the titanium alloy specimens. Extracellular matrix hydroxyapatite production was high for ceramics, but reduced for titanium specimens. The polymers allowed only a few cells to adhere, and there were no signs of extracellular matrix production. The influence of biomaterials on differentiation of large numbers of cells was analysed by using flow cytophotometry. There were similar populations of T cells and monocytes on all specimens. However, extended B cell and granulocyte populations were observed with titanium and polyethylene.

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

    Energy Technology Data Exchange (ETDEWEB)

    Umezawa, Sachiko; Yano, Hisako; Tanaka, Toshiaki; Hibi, Itsuo (National Children' s Medical Research Center, Tokyo (Japan)); Tsukimoto, Ichiro; Ishikawa, Eiji; Mouri, Yoshikazu; Murakami, Yoshiaki

    1989-07-01

    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.).

  19. Semiempirical Rules To Determine Drug Sensitivity and Ionization Efficiency in Secondary Ion Mass Spectrometry Using a Model Tissue Sample.

    Science.gov (United States)

    Vorng, Jean-Luc; Kotowska, Anna M; Passarelli, Melissa K; West, Andrew; Marshall, Peter S; Havelund, Rasmus; Seah, Martin P; Dollery, Colin T; Rakowska, Paulina D; Gilmore, Ian S

    2016-11-15

    There is an increasing need in the pharmaceutical industry to reduce drug failure at late stage and thus reduce the cost of developing a new medicine. Since most drug targets are intracellular, this requires a better understanding of the drug disposition within a cell. Secondary ion mass spectrometry has been identified as a potentially important technique to do this, as it is label-free and allows imaging in 3D with subcellular resolution and recent studies have shown promise for amiodarone. An important analytical parameter is sensitivity, and we measure this in a bovine liver homogenate reference sample for 20 drugs representing important class types relevant to the pharmaceutical industry. We also measure the sensitivity for pure drug and show, for the first time, that the secondary ion mass spectrometry (SIMS) positive ionization efficiency for small molecules is a simple power-law relationship to the log P value. This discovery will be important for advancing the understanding of the SIMS ionization process in small molecules that has, until now, been elusive. This simple relationship is found to hold true for drug doped in the bovine liver homogenate reference sample, except for fluticasone, nicardipine, and sorafenib which suffer from severe matrix suppression. This relationship provides a simple semiempirical method to determine drug sensitivity for positive secondary ions. Furthermore, we show, on chosen models, how the use of different solvents during sample preparation can affect the ionization of analytes.

  20. Environment Dictates Dependence on Mitochondrial Complex I for NAD+ and Aspartate Production and Determines Cancer Cell Sensitivity to Metformin.

    Science.gov (United States)

    Gui, Dan Y; Sullivan, Lucas B; Luengo, Alba; Hosios, Aaron M; Bush, Lauren N; Gitego, Nadege; Davidson, Shawn M; Freinkman, Elizaveta; Thomas, Craig J; Vander Heiden, Matthew G

    2016-11-08

    Metformin use is associated with reduced cancer mortality, but how metformin impacts cancer outcomes is controversial. Although metformin can act on cells autonomously to inhibit tumor growth, the doses of metformin that inhibit proliferation in tissue culture are much higher than what has been described in vivo. Here, we show that the environment drastically alters sensitivity to metformin and other complex I inhibitors. We find that complex I supports proliferation by regenerating nicotinamide adenine dinucleotide (NAD)+, and metformin's anti-proliferative effect is due to loss of NAD+/NADH homeostasis and inhibition of aspartate biosynthesis. However, complex I is only one of many inputs that determines the cellular NAD+/NADH ratio, and dependency on complex I is dictated by the activity of other pathways that affect NAD+ regeneration and aspartate levels. This suggests that cancer drug sensitivity and resistance are not intrinsic properties of cancer cells, and demonstrates that the environment can dictate sensitivity to therapies that impact cell metabolism.

  1. A sensitive method for determination of allergenic fragrance terpene hydroperoxides using liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Rudbäck, Johanna; Islam, Nurul; Nilsson, Ulrika; Karlberg, Ann-Therese

    2013-04-01

    Different compositions of monoterpenes are utilized for their pleasant scent in cosmetics and perfumes. However, the most commonly used fragrance terpenes easily oxidize upon contact with air, forming strongly skin-sensitizing hydroperoxides. Due to their thermolability and low UV absorbance, detection methods for hydroperoxides are scarce. For the first time, a simple and sensitive method using LC/ESI-MS/MS was developed to quantitatively determine hydroperoxides from the common fragrance compounds linalool, linalyl acetate, and limonene. The method was applied to autoxidized petitgrain oil and sweet orange oil. A separation was accomplished using a C3 column. The method LOD for the investigated hydroperoxides in the essential oils was below 0.3 μg/mL, corresponding to 0.3 ppm. For prevention purposes and according to EU regulations, concentrations in cosmetics exceeding 100 ppm in "rinse-off" and 10 ppm in "stay-on" products of linalool and limonene must be labeled. However, the products may still contain allergens, such as hydroperoxides, formed by oxidative degradation of their parent terpenes. The sensitivity and selectivity of the presented LC/MS/MS method enables detection of hydroperoxides from the fragrance terpenes linalool, linalyl acetate, and limonene. However, for routine measurements, the method requires further validation.

  2. The fluidity of boulder debris flows is affected by fine sediment in the pore water

    Science.gov (United States)

    Hotta, Norifumi; Kaneko, Takahiro; Iwata, Tomoyuki; Nishimoto, Haruo

    2013-04-01

    Basic equations for debris flows are frequently derived using the simple assumption of monogranular particles. However, actual debris flows include a great diversity of grain sizes, resulting in inherent features such as inverse grading, particle size segregation, and liquefaction of fine sediment. The liquefaction of fine sediment affects the fluidity of debris flows, although the behavior and influence of fine sediment in debris flows have not been examined sufficiently. This study used flume tests to detect the effect of fine sediment on the characteristics of laboratory debris flows consisting of particles with two diameters: one diameter was fixed at a large particle size, while the small diameters were varied with the experimental conditions. From the experiments, the greatest sediment concentration and flow depth were observed in the debris flows mixed with finer sediment, indicating increased flow resistance. Then, the experimental friction coefficient was compared with the theoretical friction coefficient derived by substituting the experimental values into the constitutive equations for debris flow. The theoretical friction coefficient was obtained from two models with different fine-sediment treatments: one assuming that all of the fine sediments were solid particles and the other that the particles consisted of a fluid phase involving pore water liquefaction. A discriminant index was introduced to clarify which contribution from the two models could better explain the experimental results. The comparison of the friction coefficients detected a fully liquefied state for the finest particle mixture with sediment. However, even with the same particle size, the debris flows could be regarded as a liquefied state, a solid state, or a partially liquefied transition state depending on the experimental conditions other than the sediment particle size. These results infer that the liquefaction of fine sediment in debris flows was induced not only by the

  3. 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.

  4. Micelle enhanced and native spectrofluorimetric methods for determination of sertindole using sodium dodecyl sulfate as sensitizing agent.

    Science.gov (United States)

    El-Kosasy, Amira M; Hussein, Lobna A; Sedki, Nehal G; Salama, Nahla N

    2016-01-15

    Two stability indicating spectrofluorimetric methods were developed and validated for the determination of sertindole (SER) in the presence of its acid and oxidative degradates at λ(ex) 257 nm and λ(em) 335 nm. Method A was based on measuring the native fluorescence of SER using isopropanol as solvent. Method B was based on the enhancement of native fluorescence of SER quenched in aqueous media by using micellar microenvironment created by sodium dodecyl sulfate (SDS) anionic micelles using Britton Robinson Buffer (BRB) pH3.29 as solvent. Different factors affecting fluorescence intensity; both native and enhanced, were carefully studied to reach the optimum conditions of measurements. The proposed spectrofluorimetric methods were validated in accordance with ICH guidelines and were successfully applied for the determination of SER in bulk powder and pharmaceutical preparation with high sensitivity and stability indicating power. They were also statistically compared to the manufacturer methods with no significant difference in performance.

  5. A Sensitive Voltammetric Sensor for Determination of Glutathione Based on Multiwall Carbon Nanotubes Paste Electrode Incorporating Pyrogallol Red

    Directory of Open Access Journals (Sweden)

    Mohsen Keyvanfard

    2014-06-01

    Full Text Available A new sensitive and selective electrochemical sensor was developed for determination of glutathione (GSH at the surface of carbon paste electrode (CPE modified with multi-wall carbon nanotubes (MWCNTs as a sensor and pyrogallol red (PGR as a mediator. The mechanism of GSH electrochemical behavior at the modified electrode surface was investigated by various electrochemical techniques including chronoamperometry, cyclic voltammetry (CV and square wave voltammetry (SWV. A linear calibration curve was obtained in the concentration range of GSH of 0.3–500 μmol L–1, with a limit of detection of 0.19 μmol L–1. The method was applied to the determination of GSH in urine samples with satisfactory results.

  6. Transport proteins determine drug sensitivity and resistance in a protozoan parasite, Trypanosoma brucei

    Science.gov (United States)

    Munday, Jane C.; Settimo, Luca; de Koning, Harry P.

    2015-01-01

    Drug resistance in pathogenic protozoa is very often caused by changes to the ‘transportome’ of the parasites. In Trypanosoma brucei, several transporters have been implicated in uptake of the main classes of drugs, diamidines and melaminophenyl arsenicals. The resistance mechanism had been thought to be due to loss of a transporter known to carry both types of agents: the aminopurine transporter P2, encoded by the gene TbAT1. However, although loss of P2 activity is well-documented as the cause of resistance to the veterinary diamidine diminazene aceturate (DA; Berenil®), cross-resistance between the human-use arsenical melarsoprol and the diamidine pentamidine (melarsoprol/pentamidine cross resistance, MPXR) is the result of loss of a separate high affinity pentamidine transporter (HAPT1). A genome-wide RNAi library screen for resistance to pentamidine, published in 2012, gave the key to the genetic identity of HAPT1 by linking the phenomenon to a locus that contains the closely related T. brucei aquaglyceroporin genes TbAQP2 and TbAQP3. Further analysis determined that knockdown of only one pore, TbAQP2, produced the MPXR phenotype. TbAQP2 is an unconventional aquaglyceroporin with unique residues in the “selectivity region” of the pore, and it was found that in several MPXR lab strains the WT gene was either absent or replaced by a chimeric protein, recombined with parts of TbAQP3. Importantly, wild-type AQP2 was also absent in field isolates of T. b. gambiense, correlating with the outcome of melarsoprol treatment. Expression of a wild-type copy of TbAQP2 in even the most resistant strain completely reversed MPXR and re-introduced HAPT1 function and transport kinetics. Expression of TbAQP2 in Leishmania mexicana introduced a pentamidine transport activity indistinguishable from HAPT1. Although TbAQP2 has been shown to function as a classical aquaglyceroporin it is now clear that it is also a high affinity drug transporter, HAPT1. We discuss here a

  7. Transport proteins determine drug sensitivity and resistance in a protozoan parasite, Trypanosoma brucei

    Directory of Open Access Journals (Sweden)

    Jane Claire Munday

    2015-03-01

    Full Text Available Drug resistance in pathogenic protozoa is very often caused by changes to the ‘transportome’ of the parasites. In Trypanosoma brucei, several transporters have been implicated in uptake of the main classes of drugs, diamidines and melaminophenyl arsenicals. The resistance mechanism had been thought to be due to loss of a transporter known to carry both types of agents: the aminopurine transporter P2, encoded by the gene TbAT1. However, although loss of P2 activity is well-documented as the cause of resistance to the veterinary diamidine diminazene aceturate (Berenil®, cross-resistance between the human-use arsenical melarsoprol and the diamidine pentamidine (MPXR is the result of loss of a separate High Affinity Pentamidine Transporter (HAPT1. A genome-wide RNAi library screen for resistance to pentamidine, published in 2012, gave the key to the genetic identity of HAPT1 by linking the phenomenon to a locus that contains the closely related T. brucei aquaglyceroporin genes TbAQP2 and TbAQP3. Further analysis determined that knockdown of only one pore, TbAQP2, produced the MPXR phenotype. TbAQP2 is an unconventional aquaglyceroporin with unique residues in the selectivity region of the pore, and it was found that in several MPXR lab strains the WT gene was either absent or replaced by a chimeric protein, recombined with parts of TbAQP3. Importantly, wild-type AQP2 was also absent in field isolates of T. b. gambiense, correlating with the outcome of melarsoprol treatment. Expression of a wild-type copy of TbAQP2 in even the most resistant strain completely reversed MPXR and re-introduced HAPT1 function and transport kinetics. Expression of TbAQP2 in Leishmania mexicana introduced a pentamidine transport activity indistinguishable from HAPT1. Although TbAQP2 has been shown to function as a classical aquaglyceroporin it is now clear that it is also a high affinity drug transporter, HAPT1. We discuss here a possible structural rationale for this

  8. Properties of recombinant human N1-acetylpolyamine oxidase (hPAO): potential role in determining drug sensitivity.

    Science.gov (United States)

    Wang, Yanlin; Hacker, Amy; Murray-Stewart, Tracy; Frydman, Benjamin; Valasinas, Aldonia; Fraser, Alison V; Woster, Patrick M; Casero, Robert A

    2005-07-01

    The recent cloning of the mammalian gene coding for N(1)-acetylpolyamine oxidase (PAO) provides the opportunity to directly examine the role of human PAO (hPAO) in polyamine homeostasis as well as its potential role in determining cellular response to antitumor polyamine analogues. To facilitate the study of this enzyme, the production, purification, and characterization of the recombinant hPAO is reported. hPAO oxidizes N(1)-acetylspermidine (K(m)=2.1 microM, K(cat)=15.0 s(-1)) and has very high affinity for N(1)-acetylspermine (K(m)=0.85 microM, K(cat)=31.7 s(-1)). The recombinant hPAO does not efficiently oxidize spermine, thereby demonstrating a significant difference in substrate specificity from the previously described human spermine oxidase PAOh1/SMO. Importantly, hPAO demonstrates the ability to oxidize a subset of antitumor polyamine analogues, suggesting that this oxidase activity could have a significant effect on determining tumor sensitivity to these or similar agents. Transfection of A549 human lung cancer cells with an hPAO-expressing plasmid leads to a profound decrease in sensitivity to those analogues which act as substrates, confirming its potential to alter drug response. One similarity that hPAO shares with human PAOh1/SMO, is that certain oligoamine analogues are potent inhibitors of its oxidase activity. The results of these studies demonstrate how changes in polyamine catabolism may affect drug response.

  9. Molecularly imprinted solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of safranine T in wolfberry.

    Science.gov (United States)

    Su, Zihao; Zhai, Haiyun; Chen, Zuanguang; Zhou, Qing; Li, Jiangmei; Liu, Zhenping

    2014-02-01

    A method was developed to sensitively determine safranine T in wolfberry by molecularly imprinted solid-phase extraction (MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC-LIF). The MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using safranine T, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions and the morphologies of inner polymers were characterized by scanning electron microscopy (SEM). The mean recoveries of safranine T in wolfberry ranged from 91.2 % to 92.9 % and the intraday and interday relative standard deviation (RSD) values all ranged from 3.4 % to 4.2 %. Good linearity was obtained over 0.001-1.0 μg mL(-1) (r = 0.9999) with a detection limit (S/N = 3) of 0.4 ng g(-1). Under the selected conditions, enrichment factors of over 90-fold were obtained and the extraction on the monolithic column effectively cleaned up the wolfberry matrix. The results demonstrated that the proposed MISPE-HPLC-LIF method could be applied to sensitively determine safranine T in wolfberry.

  10. 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.

  11. Sensitive and selective determination of NO(2)(-) ion in aqueous samples using modified gold nanoparticle as a colorimetric probe.

    Science.gov (United States)

    Nam, Yun-Sik; Noh, Kown-Chul; Kim, Nak-Kyoon; Lee, Yeonhee; Park, Hee-Kyung; Lee, Kang-Bong

    2014-07-01

    A sensitive and selective colorimetric method for determination of nitrite ion in aqueous samples was developed using 1-(2-mercaptoethyl)-1, 3, 5-triazinane-2, 4, 6-trione-functionalized gold nanoparticles (MTT-GNPs). The nitrite ion seems to be used as a "molecular bridge", which can form NH---N and NH---O hydrogen bonds with the MTT-GNPs, shorten the interparticle distance, and induce the aggregation of the MTT-GNPs. This aggregation results in a dramatic change from wine-red to purple-gray color. Therefore, the concentration of nitrite ion in environmental samples can be quantitatively detected using the MTT-GNPs sensor by the naked eyes or UV-vis spectrometer. Moreover, investigations have revealed the sensitivity of the detection could be clearly improved by modulating pH of the solution, which led to a more rapid color change in the optimized GNPs system. The absorption ratios (A790/A535) of the modified GNPs solution exhibited a linear correlation with nitrite ion concentrations and the limit of detection was 1 ppm. This cost effective sensing system allows for the rapid and facile determination of the concentration of [Formula: see text] ions in aqueous samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. 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.

  13. A highly sensitive quantitative real-time PCR assay for determination of mutant JAK2 exon 12 allele burden.

    Directory of Open Access Journals (Sweden)

    Lasse Kjær

    Full Text Available Mutations in the Janus kinase 2 (JAK2 gene have become an important identifier for the Philadelphia-chromosome negative chronic myeloproliferative neoplasms. In contrast to the JAK2V617F mutation, the large number of JAK2 exon 12 mutations has challenged the development of quantitative assays. We present a highly sensitive real-time quantitative PCR assay for determination of the mutant allele burden of JAK2 exon 12 mutations. In combination with high resolution melting analysis and sequencing the assay identified six patients carrying previously described JAK2 exon 12 mutations and one novel mutation. Two patients were homozygous with a high mutant allele burden, whereas one of the heterozygous patients had a very low mutant allele burden. The allele burden in the peripheral blood resembled that of the bone marrow, except for the patient with low allele burden. Myeloid and lymphoid cell populations were isolated by cell sorting and quantitative PCR revealed similar mutant allele burdens in CD16+ granulocytes and peripheral blood. The mutations were also detected in B-lymphocytes in half of the patients at a low allele burden. In conclusion, our highly sensitive assay provides an important tool for quantitative monitoring of the mutant allele burden and accordingly also for determining the impact of treatment with interferon-α-2, shown to induce molecular remission in JAK2V617F-positive patients, which may be a future treatment option for JAK2 exon 12-positive patients as well.

  14. 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.

  15. Sensitive spectrofluorimetric methods for determination of ethopabate and amprolium hydrochloride in chicken plasma and their residues in food samples.

    Science.gov (United States)

    El-Kosasy, Amira M; Hussein, Lobna A; Magdy, N; Abbas, Mahmoud M

    2015-01-01

    Two sensitive and selective spectrofluorimetric methods are proposed to determine ethopabate (ETH) and amprolium hydrochloride (AMP). First derivative synchronous spectrofluorimetry determines the natively fluorescent ethopabate at 288 nm in presence of amprolium hydrochloride which is a non fluorescent quaternary compound with average recovery 100.54±0.721 over a concentration range of 0.01-0.8 μg/mL. Limits of detection (LOD) and quantification (LOQ) are 0.002 and 0.007 μg/mL, respectively. The second method is direct synchronous spectrofluorimetry for determining amprolium hydrochloride at 362 nm after a reaction with 5% NaOH and 0.08% potassium ferricyanide that is optimized by a two-level factorial design. This method is linear over a concentration range of 0.01-0.65 μg/mL with average recovery 99.4±1.28. Limits of detection (LOD) and quantification (LOQ) are 0.002 and 0.006 μg/mL, respectively. The proposed methods are found to be valid and applicable for the analysis of ETH and AMP in their veterinary formulation. They are successfully applied to determine the studied drugs in chicken plasma and their residues in chicken muscle, liver, egg and chicken-based baby food product with recoveries in the ranges of 95.71-108.73% and 97.36-111.89% and for ETH and AMP, respectively.

  16. 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) ...

  17. Simultaneous determination of dissolved inorganic chromium species in wastewater/natural waters by surfactant sensitized catalytic kinetic spectrophotometry

    Directory of Open Access Journals (Sweden)

    Ramazan Gürkan

    2017-02-01

    Full Text Available A simple, rapid, highly accurate and sensitive kinetic method is proposed for determining chromium(VI. The method is based on its catalytic effect on the oxidation of Celestine blue (CB+ by H2O2 in the presence of 2,2′-bipyridyl (Bipyr and cetylpyridinium chloride (CPC at pH 6.50. The reaction was monitored spectrophotometrically by measuring the absorbance of indicator dye at 645 nm. The analytical variables, which have influences on the sensitivity, were investigated and the optimum conditions were established. The optimized conditions made it possible to determine and speciate chromium in a linear range of 5–200 μg L−1 with a detection limit of 0.65 μg L−1. The recoveries and relative standard deviations (RSDs for the determination of 10, 25, 75 and 150 μg L−1 Cr(VI (n: 5 were in the range of 99.0–99.8% and 0.2–3.5%, respectively. The selectivity was also studied and greatly enhanced by adding a suitable masking mixture. The method was successfully applied to the simultaneous analysis of Cr(III and Cr(VI in natural water and waste water samples with a recovery changing in the range of 95–103% for Cr(III and 100–104% for Cr(VI. Its accuracy was validated by the analysis of certified reference materials with good agreement between certified and found values.

  18. Sensitive amperometric determination of hydrazine using a carbon paste electrode modified with silver-doped zeolite L nanoparticles

    Indian Academy of Sciences (India)

    NEDA SALEK GILANI; SEYED NASER AZIZI; SHAHRAM GHASEMI

    2017-02-01

    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 diffraction (XRD), Fourier transform infrared (FTIR), scanning electronic microscopy (SEM) and Brunauer–Emmett–Teller (BET). Silver-exchanged nanozeolite L (Ag/L) was prepared and mixed with carbon paste to prepare the modified electrode. Cyclic voltammetry studies revealed the high performance of Ag/L–CPE for electrocatalytic oxidation of hydrazine. Two linear ranges were detected in the amperometric detection of hydrazine. The first range was from10 $\\mu$M to 0.4 mM with sensitivity of 103.13 $\\mu$A mM$^{−1}$ and the second one was from 0.4 to 4mM with sensitivity of 58.131 $\\mu$A mM$^{−1}$. The response time and detection limit ($S/N = 3$) of this sensor were determined to be 2 s and 1.5 $\\mu$M, respectively. The unique porous structure of nanozeolite L offers a promising catalyst support candidate for efficient electrochemical sensing of hydrazine. The sensor exhibited appreciable repeatability, reproducibility and stability, and was able to detect hydrazine in the presence of even 500-fold excess concentrations of interfering species. Also, the sensor was used to determine hydrazine concentration in water samples with satisfactory results.

  19. Sensitive and selective methods for the determination of rizatriptan benzoate in pharmaceuticals using N-bromosuccinimide and two dyes

    Directory of Open Access Journals (Sweden)

    Kudige Nagaraj Prashanth

    2015-05-01

    Full Text Available One titrimetric and two spectrophotometric methods are described for the determination of rizatriptan benzoate (RTB in bulk drugs and in tablets. The methods use N-bromosuccinimide (NBS as an analytical reagent, janus green (JG and calmagite (CMG as auxiliary reagents. All the three methods are indirect in which the unreacted NBS is determined after the reaction between RTB and NBS is judged complete by iodometric back titration (method A or by reacting with a fixed amount of either janus green (method B or calmagite (method C followed by the measurement of absorbance at 620 nm (method B or 540 nm (method C. Titrimetry allows the determination of 1–10 mg of RTB and follows a reaction stoichiometry of 1:3 (RTB:NBS, whereas spectrophotometric methods are applicable over the concentration ranges of 0.5–8.0 μg ml−1 in method B and 1.5–30.0 μg ml−1 in method C. Method B with a calculated molar absorptivity of 3.03 × 104 L mol−1 cm−1 is the second most sensitive spectrophotometric method ever developed for RTB. The quality control/assurance parameters such as limits of detection (LOD, quantification (LOQ and Sandelle’s sensitivity values are also reported for the spectrophotometric method. The accuracy and precision of the methods were studied on intra-day and inter-day basis. No interference was observed from common pharmaceutical adjuvants. Statistical comparison of the results with a reference method showed excellent agreement, and indicates no significant difference in accuracy and precision. The reliability of the methods was further ascertained by recovery studies via standard addition procedures.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jomrit, Juntratip [Department of Biotechnology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400 (Thailand); Center of Excellence for Agricultural Biotechnology: (AG-BIO/PERDO-CHE), Bangkok (Thailand); Summpunn, Pijug [Department of Biotechnology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400 (Thailand); Meevootisom, Vithaya [Department of Microbiology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400 (Thailand); Center of Excellence for Agricultural Biotechnology: (AG-BIO/PERDO-CHE), Bangkok (Thailand); Wiyakrutta, Suthep, E-mail: scsvy@mahidol.ac.th [Department of Microbiology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400 (Thailand); Center of Excellence for Agricultural Biotechnology: (AG-BIO/PERDO-CHE), Bangkok (Thailand)

    2011-02-25

    Research highlights: {yields} Stereochemical mechanism of PLP enzymes is important but difficult to determine. {yields} This new method is significantly less complicated than the previous ones. {yields} This assay is as sensitive as the radioactive based method. {yields} LC-MS/MS positively identify the analyte coenzyme. {yields} The method can be used with enzyme whose apo form is unstable. -- Abstract: 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 {sup 2}H{sub 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'-{sup 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 {sup 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 {sup 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 {sup 2}H. The method was highly sensitive that for the aminotransferase with ca. 50 kDa subunit molecular weight, only 2 mg 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.

  1. The effects of taurine, hypotaurine, and taurine homologs on erythrocyte morphology, membrane fluidity and cytoskeletal spectrin alterations due to diabetes, alcoholism and diabetes-alcoholism in the rat.

    Science.gov (United States)

    Gossai, Davekanand; Lau-Cam, Cesar A

    2009-01-01

    Taurine (TAU) and compounds representing a TAU analog (hypotaurine = HYTAU) or homolog (aminomethanesulfonic acid = AMSA, homotaurine = HMTAU) were tested for their counteracting effects against alterations in erythrocyte (RBC) morphology, membrane fluidity and cytoskeletal spectrin distribution due to diabetes, alcoholism and diabetes-alcoholism in male Goto-Kakizaki rats (made diabetic with a high fat diet and alcoholic upon feeding on a flavored alcohol solution) and Wistar-Kyoto rats (serving as controls). Both diabetes and alcoholism changed the RBC discoidal biconcave shape to a spiculated one, lowered membrane fluidity, and caused spectrin to become marginalized. While AMSA and HYTAU returned the RBC shape to normal, HMTAU made it only discoidal, and TAU was without effect. All test compounds, but TAU, maintained the membrane fluidity normal; and HYTAU and AMSA, but not TAU or HMTAU, kept spectrin uniformly distributed. The noted effects were correlated with compound structure and RBC values for malondialdehyde and cholesterol/phospholipid ratio.

  2. 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.

  3. Diminished Lipid Raft SNAP23 Increases Blood Pressure by Inhibiting the Membrane Fluidity of Vascular Smooth-Muscle Cells.

    Science.gov (United States)

    Yoon, Mi So; Won, Kyung-Jong; Kim, Do-Yoon; Hwang, Dae Il; Yoon, Seok Won; Jung, Seung Hyo; Lee, Kang Pa; Jung, Dongju; Choi, Wahn Soo; Kim, Bokyung; Lee, Hwan Myung

    2015-01-01

    Synaptosomal-associated protein 23 (SNAP23) is involved in microvesicle trafficking and exocytosis in various cell types, but its functional role in blood pressure (BP) regulation has not yet been defined. Here, we found that lipid raft SNAP23 expression was much lower in vascular smooth-muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) than in those from normotensive Wistar-Kyoto (WKY) rats. This led us to investigate the hypothesis that this lower expression may be linked to the spontaneous hypertension found in SHR. The expression level of lipid raft SNAP23 and the fluidity in the plasma membrane of VSMCs were lower in SHR than in WKY rats. Cholesterol content in the VSMC membrane was higher, but the secreted cholesterols found in VSMC-conditioned medium and in the blood serum were lower in SHR than in WKY rats. SNAP23 knockdown in WKY rat VSMCs reduced the membrane fluidity and increased the membrane cholesterol level. Systemic overexpression of SNAP23 in SHR resulted in an increase of cholesterol content in their serum, a decrease in cholesterol in their aorta and the reduction of their BP. Our findings suggest that the low expression of the lipid raft SNAP23 in VSMCs might be a potential cause for the characteristic hypertension of SHR.

  4. Construction of five-piece segment using high-fluidity concrete; Koryudo togo bunkatsu segment no seko jisseki

    Energy Technology Data Exchange (ETDEWEB)

    Suda, Y.; Fukuzawa, I.; Matsunaga, H. [Tokyo Electric Power Co. Inc., Tokyo (Japan)

    1998-09-05

    After reviewing RC segment materials and the number of joints required, a segment of five equal pieces using high-fluidity concrete is employed in conduit construction work (for 500kV transmission lines) near Hommoku Wharf, Kanagawa Prefecture, which is for reduction in the shield tunnel construction cost (segment cost rate approximately 1/3). The use of high-fluidity concrete raises the materials cost a little but the factory overhead, expenditures for fabrication and formwork construction are lowered because some working processes may be dispensed with, such as the processes of compaction by vibration, surface finish, and formwork movement, and because the formwork main body may be simplified in structure. Although the standard tunnel specifications mention a segment consisting of 6 pieces, the 5-piece segment adopted in this construction work lowers the cost approximately 20% thanks to reduction in the numbers of joints between segment pieces and between rings. In the shield tunnelling process, assembly is easier and the construction work is executed without hitches deserving special mention. The new technique is comparable to the conventional ones in terms of quality and process management. Since the number of joints per piece between rings is reduced from the 3 in the conventional method to the 2 in this new method, two core-sensing pins are provided per piece between rings for assuring accuracy and shortening time in assembling. 2 refs., 8 figs., 11 tabs.

  5. Estradiol Modulates Membrane-Linked ATPases, Antioxidant Enzymes, Membrane Fluidity, Lipid Peroxidation, and Lipofuscin in Aged Rat Liver

    Directory of Open Access Journals (Sweden)

    Pardeep Kumar

    2011-01-01

    Full Text Available Free radical production and oxidative stress are known to increase in liver during aging, and may contribute to the oxidative damage. These changes increase during menopausal condition in females when the level of estradiol is decreased. The objective of this study was to observe the changes in activities of membrane linked ATPases (Na+K+ ATPase, Ca2+ ATPase, antioxidant enzymes (superoxide dismutase, glutathione-S-transferase, lipid peroxidation levels, lipofuscin content and membrane fluidity occurring in livers of female rats of 3, 12 and 24 months age groups, and to see whether these changes are restored to 3 months control levels rats after exogenous administration of 17-β-estradiol (E2. The aged rats (12 and 24 months were given subcutaneous injection of E2 (0.1 μg/g body weight daily for one month. The results obtained in the present work revealed that normal aging was associated with significant decrease in the activities of membrane linked ATPases, antioxidant enzymes, membrane fluidity and an increase in lipid peroxidation and lipofuscin content in livers of aging female rats. The present study showed that E2 treatment reversed the changes to normal levels. E2 treatment may be beneficial in preventing some of the age related changes in the liver by increasing antioxidant defenses.

  6. Describing Temperature-Dependent Self-Diffusion Coefficients and Fluidity of 1- and 3-Alcohols with the Compensated Arrhenius Formalism.

    Science.gov (United States)

    Fleshman, Allison M; Forsythe, Grant E; Petrowsky, Matt; Frech, Roger

    2016-09-22

    The location of the hydroxyl group in monohydroxy alcohols greatly affects the temperature dependence of the liquid structure due to hydrogen bonding. Temperature-dependent self-diffusion coefficients, fluidity (the inverse of viscosity), dielectric constant, and density have been measured for several 1-alcohols and 3-alcohols with varying alkyl chain lengths. The data are modeled using the compensated Arrhenius formalism (CAF). The CAF follows a modified transition state theory using an Arrhenius-like expression to describe the transport property, which consists of a Boltzmann factor containing an energy of activation, Ea, and an exponential prefactor containing the temperature-dependent solution dielectric constant, εs(T). Both 1- and 3-alcohols show the Ea of diffusion coefficients (approximately 43 kJ mol(-1)) is higher than the Ea of fluidity (approximately 35 kJ mol(-1)). The temperature dependence of the exponential prefactor in these associated liquids is explained using the dielectric constant and the Kirkwood-Frölich correlation factor, gk. It is argued that the dielectric constant must be used to account for the additional temperature dependence due to variations in the liquid structure (e.g., hydrogen bonding) for the CAF to accurately model the transport property.

  7. Gradient enhanced-fluidity liquid hydrophilic interaction chromatography of ribonucleic acid nucleosides and nucleotides: A "green" technique.

    Science.gov (United States)

    Beilke, Michael C; Beres, Martin J; Olesik, Susan V

    2016-03-04

    A "green" hydrophilic interaction liquid chromatography (HILIC) technique for separating the components of mixtures with a broad range of polarities is illustrated using enhanced-fluidity liquid mobile phases. Enhanced-fluidity liquid chromatography (EFLC) involves the addition of liquid CO2 to conventional liquid mobile phases. Decreased mobile phase viscosity and increased analyte diffusivity results when a liquefied gas is dissolved in common liquid mobile phases. The impact of CO2 addition to a methanol:water (MeOH:H2O) mobile phase was studied to optimize HILIC gradient conditions. For the first time a fast separation of 16 ribonucleic acid (RNA) nucleosides/nucleotides was achieved (16min) with greater than 1.3 resolution for all analyte pairs. By using a gradient, the analysis time was reduced by over 100% compared to similar separations conducted under isocratic conditions. The optimal separation using MeOH:H2O:CO2 mobile phases was compared to MeOH:H2O and acetonitrile:water (ACN:H2O) mobile phases. Based on chromatographic performance parameters (efficiency, resolution and speed of analysis) and an assessment of the environmental impact of the mobile phase mixtures, MeOH:H2O:CO2 mixtures are preferred over ACN:H2O or MeOH:H2O mobile phases for the separation of mixtures of RNA nucleosides and nucleotides.

  8. A new method for determining the sensitivity of X-ray imaging observations and the X-ray number counts

    CERN Document Server

    Georgakakis, A; Laird, E S; Aird, J; Trichas, M

    2008-01-01

    We present a new method for determining the sensitivity of X-ray imaging observations, which correctly accounts for the observational biases that affect the probability of detecting a source of a given X-ray flux, without the need to perform a large number of time consuming simulations. We use this new technique to estimate the X-ray source counts in different spectral bands (0.5-2, 0.5-10, 2-10 and 5-10keV) by combining deep pencil-beam and shallow wide-area Chandra observations. The sample has a total of 6295 unique sources over an area of $\\rm 11.8deg^2$ and is the largest used to date to determine the X-ray number counts. We determine, for the first time, the break flux in the 5-10 keV band, in the case of a double power-law source count distribution. We also find an upturn in the 0.5-2keV counts at fluxes below about 6e-17erg/s/cm2. We show that this can be explained by the emergence of normal star-forming galaxies which dominate the X-ray population at faint fluxes. The fraction of the diffuse X-ray bac...

  9. 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).

  10. A rapid and sensitive method for the determination of hypusine in proteins and its distribution and developmental changes.

    Science.gov (United States)

    Sano, A; Miyake, M; Kakimoto, Y

    1984-07-30

    A simple and sensitive method for determining hypusine in proteins was developed. A greater part of amino acids in the acid hydrolysate of proteins was separated from hypusine by treatment with an ion-exchange resin. The sample containing partially purified hypusine was then analyzed by high-performance liquid chromatography using the post-column derivatization method with o-phthalaldehyde. The recovery rate of hypusine through the overall procedure was more than 95%. Using this method, the distribution and developmental changes of hypusine in proteins were determined. The amino acid was found in proteins of all examined organs of rat. Its concentration was 5-40 nmol/g protein. The subcellular distribution in rat liver was also determined. About 60% of total amount of hypusine was present in the proteins of cytoplasmic and microsomal fractions and its relative concentration was high in the proteins of microsome and lysosome and low in mitochondria. In developing rat, the concentration of hypusine in the brain proteins was relatively high during the first 2 or 3 weeks of postnatal life and then decreased until adulthood. Its concentration in the liver proteins was highest at birth and then decreased continuously to the adult level.

  11. A novel polymer inclusion membranes based optode for sensitive determination of Al³⁺ ions.

    Science.gov (United States)

    Suah, Faiz Bukhari Mohd; Ahmad, Musa; Heng, Lee Yook

    2015-06-05

    A novel approach for the determination of Al(3+) from aqueous samples was developed using an optode membrane produced by physical inclusion of Al(3+) selective reagent, which is morin into a plasticized poly(vinyl chloride). The inclusion of Triton X-100 was found to be valuable and useful for enhancing the sorption of Al(3+) ions from liquid phase into the membrane phase, thus increasing the intensity of optode's absorption. The optode showed a linear increase in the absorbance at λ(max)=425 nm over the concentration range of 1.85×10(-6)-1.1×10(-4) mol L(-1) (0.05-3 μg mL(-1)) of Al(3+) ions in aqueous solution after 5 min. The limit of detection was determined to be 1.04×10(-6) mol L(-1) (0.028 μg mL(-1)). The optode developed in the present work was easily prepared and found to be stable, has good mechanical strength, sensitive and reusable. In addition, the optode was tested for Al(3+) determination in lake water, river water and pharmaceutical samples, which the result was satisfactory.

  12. Sensitive determination of cadmium in water samples by room temperature ionic liquid-based preconcentration and electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Martinis, Estefania M. [Laboratory of Environmental Research and Services of Mendoza (LISAMEN), (CCT - CONICET - Mendoza), Av. Ruiz Leal S/N Parque General San Martin, C.C. 131, M 5502 IRA Mendoza (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Olsina, Roberto A. [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Departamento de Quimica Analitica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis (Argentina); Altamirano, Jorgelina C. [Laboratory of Environmental Research and Services of Mendoza (LISAMEN), (CCT - CONICET - Mendoza), Av. Ruiz Leal S/N Parque General San Martin, C.C. 131, M 5502 IRA Mendoza (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza (Argentina); Wuilloud, Rodolfo G. [Laboratory of Environmental Research and Services of Mendoza (LISAMEN), (CCT - CONICET - Mendoza), Av. Ruiz Leal S/N Parque General San Martin, C.C. 131, M 5502 IRA Mendoza (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza (Argentina)], E-mail: rwuilloud@mendoza-conicet.gov.ar

    2008-10-17

    A sensitive preconcentration methodology for Cd determination at trace levels in water samples was developed in this work. 1-Butyl-3-methylimidazolium hexafluorophosphate ([C{sub 4}MIM][PF{sub 6}]) room temperature ionic liquid (RTIL) was successfully used for Cd preconcentration, as cadmium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex [Cd-5-Br-PADAP]. Subsequently, Cd was back-extracted from the RTIL phase with 500 {mu}L of 0.5 mol L{sup -1} nitric acid and determined by electrothermal atomic absorption spectrometry (ETAAS). A preconcentration factor of 40 was achieved with 20 mL of sample. The limit of detection (LOD) obtained under optimum conditions was 3 ng L{sup -1} and the relative standard deviation (R.S.D.) for 10 replicates at 1 {mu}g L{sup -1} Cd{sup 2+} concentration level was 3.5%, calculated at peak heights. The calibration graph was linear from concentration levels near the detection limits up to at least 5 {mu}g L{sup -1}. A correlation coefficient of 0.9997 was achieved. Validation of the methodology was performed by standard addition method and analysis of certified reference material (CRM). The method was successfully applied to the determination of Cd in river and tap water samples.

  13. A sensitive flow analysis system for the fluorimetric determination of low levels of formaldehyde in alcoholic beverages.

    Science.gov (United States)

    de Oliveira, Fabio Santos; Sousa, Eliane Teixeira; de Andrade, Jailson B

    2007-09-30

    A sensitive FIA method was developed for the selective determination of formaldehyde in alcoholic beverages. This method is based on the reaction of Fluoral-P (4-amine-3-pentene-2-one) with formaldehyde, leading to the formation of 3,5-diacetyl-1,4-dihydrolutidine (DDL), which fluoresces at lambda(ex)=410nm and lambda(em)=510nm. The analytical parameters were optimized by the response surface method using the Box-Behnken design. The proposed flow injection system allowed for the determination of up to 3.33x10(-5)molL(-1) of formaldehyde with R.S.D.<2.5% and a detection limit of 3.1ngmL(-1). The method was successfully applied to determine formaldehyde in alcoholic beverages, without requiring any sample pretreatment, and the results agreed with the reference at a 95% confidence level by paired t-test. In the optimized condition, the FIA system proved able to analyze up to 60 samples/h.

  14. Highly sensitive and selective electrochemical determination of dopamine and ascorbic acid at Ag/Ag{sub 2}S modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chen-Yan [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Cai, Ying-Jie [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Yang, Chien-Hsin [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan (China); Wu, Chen-Hao [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Wei, Yen [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Department of Chemistry, Drexel University, Philadelphia, PA 19104 (United States); Wen, Ten-Chin, E-mail: tcwen@mail.ncku.edu.t [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Wang, Tzong-Liu; Shieh, Yeong-Tarng [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan (China); Lin, Wen-Churng [Department of Environmental Engineering, Kun Shan University, Tainan 71016, Taiwan (China); Chen, Wen-Janq [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan (China)

    2011-02-01

    A biosensor electrode possessing highly sensitive and selective determination of dopamine (DA) is fabricated. This electrode, a silver (Ag) thin film on indium-tin-oxide glass, is treated with a silver sulfide (Ag{sub 2}S) film using electrochemical deposition. Active Ag ion is easier to form on Ag{sub 2}S than on pristine Ag, which prefers to attract ascorbic acid (AA). The Ag{sub 2}S layer reduces the oxidation potential of AA due to the electrostatic interaction, which results in well-separation of mixed oxidation responses to both of DA and AA. Besides, the Ag{sub 2}S-modified electrode exhibits dramatic electrocatalytic effect on the oxidation of DA in the presence of AA. In 0.1 M phosphate buffer solution at pH {approx} 7.0, the differential pulse voltammetric peak intensity linearly correlates with DA concentration in two regions, viz. 1.0-10, and 10-100 {mu}M, with correlation coefficient of 0.998 and 0.995, respectively. The lowest concentration limit of 1.0 {mu}M DA can be detected. The interference of AA effectively diminishes in the mixed solution. These features make the Ag{sub 2}S significant for selective and sensitive measurement of DA in the presence of excess AA.

  15. The Rapid and Sensitive Quantitative Determination of Galactose by Combined Enzymatic and Colorimetric Method: Application in Neonatal Screening.

    Science.gov (United States)

    Kianmehr, Anvarsadat; Mahrooz, Abdolkarim; Ansari, Javad; Oladnabi, Morteza; Shahbazmohammadi, Hamid

    2016-05-01

    The quantitative measurement of galactose in blood is essential for the early diagnosis, treatment, and dietary monitoring of galactosemia patients. In this communication, we aimed to develop a rapid, sensitive, and cost-effective combined method for galactose determination in dry blood spots. This procedure was based on the combination of enzymatic reactions of galactose dehydrogenase (GalDH), dihydrolipoyl dehydrogenase (DLD), and alkaline phosphates with a colorimetric system. The incubation time and the concentration of enzymes used in new method were also optimized. The analytical performance was studied by the precision, recovery, linearity, and sensitivity parameters. Statistical analysis was applied to method comparison experiment. The regression equation and correlation coefficient (R (2)) were Y = 0.0085x + 0.032 and R (2) = 0.998, respectively. This assay exhibited a recovery in the range of 91.7-114.3 % and had the limit detection of 0.5 mg/dl for galactose. The between-run coefficient of variation (CV) was between 2.6 and 11.1 %. The within-run CV was between 4.9 and 9.2 %. Our results indicated that the new and reference methods were in agreement because no significant biases exist between them. Briefly, a quick and reliable combined enzymatic and colorimetric assay was presented for application in newborn mass screening and monitoring of galactosemia patients.

  16. 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.

  17. 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.

  18. 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.

  19. Electrospun Pd nanoparticles loaded on Vulcan carbon/ conductive polymeric ionic liquid nanofibers for selective and sensitive determination of tramadol.

    Science.gov (United States)

    Fathirad, Fariba; Mostafavi, Ali; Afzali, Daryoush

    2016-10-12

    In the present work a sensitive and selective electrochemical sensor was fabricated based on a glassy carbon electrode which has been modified with Pd nanoparticles loaded on Vulcan carbon/conductive polymeric ionic liquid composite nanofibers. The nanostructures were characterized by UV-Vis, FT-IR, FESEM, EDX and XRD techniques. The electrochemical study of the modified electrode, as well as its efficiency for the electrooxidation of tramadol was described in 0.1 M phosphate buffered solution (PBS) (pH 7.0) using cyclic voltammetry, linear sweep voltammetry, chronoamperometry and square wave voltammetry as diagnostic techniques. It has been found that application of the composite nanofibers result in a sensitivity enhancement and a considerable decrease in the anodic overpotential, leading to negative shifts about 200 mV in peak potential. The results exhibit a linear dynamic range from 0.05 μM to 200 μM and a detection limit of 0.015 μM for tramadol. Finally, the modified electrode was used for the determination of tramadol in pharmaceutical and biological samples.

  20. Rapid and sensitive high performance liquid chromatographic determination of zonisamide in human serum application to a pharmacokinetic study

    Directory of Open Access Journals (Sweden)

    M B Majnooni

    2012-01-01

    Full Text Available An accurate and very rapid method for determination of zonisamide an antiepileptic drug, in human serum is described. The analytical procedure involves liquid-liquid extraction of the analyte and an internal standard (vanillin from human serum by ethyl acetate as extracting solvent. Chromatographic separation was achieved using a monolithic C18 analytical column and a mixture of 0.05 M phosphate buffer containing triethylamine (1 ml/l; pH 2.7 and methanol (83:17 v/v was used as the mobile phase. The detection wavelength was set at 240 nm. The calibration curve was linear over a concentration range of 0.015-6.4 μg/ml of zonisamide in human serum. The total run time of analysis was 3.5 min and the lower limits of detection and quantification were 0.005 and 0.015 μg/ml, respectively. The method validation was carried out in terms of specificity, sensitivity, linearity, precision, accuracy and stability. The validated method was applied in a randomised crossover bioequivalence study of two different zonisamide preparations in 24 healthy volunteers, and the assay was sensitive enough to measure drug levels up to 8 days following a single dose administration of zonisamide.

  1. A miniature photoelectrochemical sensor based on organic electrochemical transistor for sensitive determination of chemical oxygen demand in wastewaters.

    Science.gov (United States)

    Liao, Jianjun; Lin, Shiwei; Zeng, Min; Yang, Yue

    2016-05-01

    A three-electrode configuration is often required in the conventional photoelectrochemical measurements. Nevertheless, one common drawback is the reference electrode and the counter electrode used in the measurements, which has been proved to be an impediment for the miniaturization. In this study, a simple, cost-effective and miniature photoelectrochemical sensor based on high sensitive organic electrochemical transistor (OECT) is developed and used for the determination of chemical oxygen demand (COD) in wastewaters. The devices show detection limit down to 0.01 mg/L COD, which is two orders of magnitude better than that of the conventional photoelectrochemical method. The excellent sensing performance can be contributed to the novel sensing mechanism of OECT devices. That is, the devices are sensitive to the potential changes induced by the photoelectrochemical reaction on TiO2 nanotube arrays gate electrodes. Real sample analyses are also carried out. The results demonstrate that the measured COD values using the OECT devices and the standard dichromate methods are in a good agreement. Since the proposed sensor is constructed on a miniature transistor, it is expected that the device shows a promising application on the integrated COD monitoring platform.

  2. A sensitive and specific method for isoniazid determination based on selective adsorption using an isoniazid ion-selective piezoelectric sensor.

    Science.gov (United States)

    Yao, S; Li, W; Su, X; Zuo, X; Wei, W

    1999-10-01

    A selective, sensitive and simple ion-selective piezoelectric (ISP) sensor was developed for the direct determination of isoniazid (INH) in body fluids. Based on sensitive mass response of piezoelectric quartz crystal and selective adsorption/desorption across the modified film, the ISP sensor was fabricated by coating a PVC film containing activant on one electrode of a thickness-shear mode piezoelectric quartz crystal. The observed frequencies of ISP sensor were found to decrease with the increase of the INH concentration in a 0.1 M NaNO(3) solution. In this paper, three activants, INH-phosphotungstate (I), INH-silicotungstate (II), and INH-[BiI(4)](-) (III), were synthesized and investigated. Calibration graphs were linear from 6x10(-8) to 2x10(-3) M for I, 2x10(-7) to 2x10(-3) M for II and 2x10(-7) to 2x10(-3) M for III, with detection limits 6x10(-8) M for I, 2x10(-7) M for II and 2x10(-7) M for III, in a 0.1 M NaNO(3) solution at pH 7.0 and 37 degrees C. Recoveries were from 98% to 102% with R.S.D. up to 2%. Results for real samples obtained by the proposed method agreed well with those obtained by the conventional pharmacopeia method.

  3. Progress in the development of ATHAM-Fluidity: A new high-resolution atmospheric model for simulating localised extreme weather events

    Science.gov (United States)

    Savre, Julien; Herzog, Michael; Percival, James; Pain, Chris

    2016-04-01

    Within the framework of the EU FP7-PEARL (Preparing for Extreme And Rare events in coastaL regions) project, a new high-resolution non hydrostatic atmospheric model is currently developed: ATHAM-Fluidity. Unlike many existing atmospheric models, ATHAM-Fluidity's dynamical core is based on a mixed finite-element discretisation designed to operate on unstructured and adaptive meshes, for an optimized use of computational power. The model is designed to simulate extreme weather conditions at local scales (on the order of 50x50 km2) and will ultimately help better understand and assess the impacts of heavy precipitation events in coastal areas. As such, ATHAM-Fluidity will constitute an important component of a suite of multi-physics models, including for example storm surge and flood modelling systems, whose role will particularly consist in producing high-resolution precipitation maps in areas of interest. A series of case studies identified within PEARL (for example Greve, Denmark, an area particularly vulnerable to floods and storm surges) will be further investigated using ATHAM-Fluidity and this integrated modelling framework. In order to successfully achieve its tasks, ATHAM-Fluidity must be equipped with a series of physical parameterisations to capture the formation and evolution of clouds and heavy precipitation. After a careful evaluation of ATHAM-Fluidity under dry atmospheric conditions [Savre et al., submitted to MWR 2015] for which the performances of the dynamical core and mesh adaptivity algorithm have been assessed, the model has recently been extended to handle moist atmospheric conditions and clouds. These new developments include the implementation of ATHAM's active tracer concept to account for atmospheric moisture and hydrometeors, as well as a warm two-moment bulk microphysics scheme to parameterise the formation and evolution of liquid clouds and precipitation. In addition, a turbulence diffusion closure, specifically designed for Large Eddy

  4. Rapid and Sensitive Method for Quantitative Determination of Lopinavir and Ritonavir in Human Plasma by Liquid Chromatography- Tandem Mass Specrtometry

    Directory of Open Access Journals (Sweden)

    G. A. Temghare

    2009-01-01

    Full Text Available A rapid and sensitive liquid chromatography-mass spectrometric (LC-MS-MS method for the simultaneous determination of lopinavir and ritonavir in human plasma using abacavir as internal standard has been developed and validated. Sample preparation of plasma involved solid phase extraction. Detection was performed using an Applied Biosystems Sciex API 2000 Mass spectrometer. The assay of lopinavir and ritonavir was linear over the range of 50 ng mL-1 to 20000 ng mL -1 and 20 ng mL -1 to 3000 ng mL-1 respectively with a precision of <15% and accuracy in the range of 85-115%. The limit of quantification in plasma for lopinavir and ritonavir was 50 ng mL -1 and 20 ng mL -1 respectively. The described method has the advantage of being rapid and easy and it could be applied in therapeutic monitoring of these drugs in human plasma

  5. Determination of heat transfer into a wedge model in a hypersonic flow using temperature-sensitive paint

    Science.gov (United States)

    Risius, Steffen; Beck, Walter H.; Klein, Christian; Henne, Ulrich; Wagner, Alexander

    2017-09-01

    Heat loads on spacecraft traveling at hypersonic speed are of major interest for their designers. Several tests using temperature-sensitive paints (TSP) have been carried out in long duration shock tunnels to determine these heat loads; generally paint layers were thin, so that certain assumptions could be invoked to enable a good estimate of the thermal parameter ρck (a material property) to be obtained—the value of this parameter is needed to determine heat loads from the TSP. Very few measurements have been carried out in impulse facilities [viz. shock tunnels such as the High Enthalpy Shock Tunnel Göttingen (HEG)], where test times are much shorter. Presented here are TSP temperature measurements and subsequently derived heat loads on a ramp model placed in a hypersonic flow in HEG (specific enthalpy h 0 = 3.3 MJ kg-1, Mach number M = 7.4, temperature T ∞ = 277 K, density ρ ∞ = 11 g m-3). A number of fluorescence intensity images were acquired, from which, with the help of calibration data, temperature field data on the model surface were determined. From these the heat load into the surface was calculated, using an assumption of a 1D, semi-infinite heat transfer model. ρck for the paint was determined using an insitu calibration with a Medtherm coaxial thermocouple mounted on the model; Medtherm ρck is known. Finally presented are sources of various measurement uncertainties, arising from: (1) estimation of ρck; (2) intensity measurement in the chosen interrogation area; (3) paint time response.

  6. A highly sensitive fluorimetric method for determination of lenalidomide in its bulk form and capsules via derivatization with fluorescamine

    Directory of Open Access Journals (Sweden)

    Darwish Ibrahim A

    2012-10-01

    Full Text Available Abstract Background Lenalidomide (LND is a potent novel thalidomide analog which demonstrated remarkable clinical activity in treatment of multiple myeloma disease via a multiple-pathways mechanism. The strong evidences-based clinical success of LND in patients has led to its recent approval by US-FDA under the trade name of Revlimid® capsules by Celgene Corporation. Fluorimetry is a convenient technique for pharmaceutical quality control, however there was a fluorimetric method for determination of LND in its bulk and capsules. Results A novel highly sensitive and simple fluorimetric method has been developed and validated for the determination of lenalidmide (LND in its bulk and dosage forms (capsules. The method was based on nucleophilic substitution reaction of LND with fluorescamine (FLC in aqueous medium to form a highly fluorescent derivative that was measured at 494 nm after excitation at 381 nm. The factors affecting the reaction were carefully studied and optimized. The kinetics of the reaction was investigated, and the reaction mechanism was postulated. Under the optimized conditions, linear relationship with good correlation coefficient (0.9999 was found between the fluorescence intensity and LND concentration in the range of 25–300 ng/mL. The limits of detection and quantitation for the method were 2.9 and 8.7 ng/mL, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 1.4%. The proposed method was successfully applied to the determination of LND in its bulk form and pharmaceutical capsules with good accuracy; the recovery values were 97.8–101.4 ± 1.08–2.75%. Conclusions The proposed method is selective and involved simple procedures. In conclusion, the method is practical and valuable for routine application in quality control laboratories for determination of LND.

  7. Retardation signal for fluorescent determination of total protein content via rapid and sensitive chip moving reaction boundary electrophoretic titration.

    Science.gov (United States)

    Wang, Houyu; Shi, Yongting; Yan, Jian; Dong, Jingyu; Li, Si; Xiao, Hua; Xie, Haiyang; Fan, Liu-Yin; Cao, Cheng-Xi

    2014-03-18

    A novel concept and theory of moving reaction boundary (MRB) retardation signal (RMRB) was advanced for determination of total protein content via MRB electrophoretic titration (MRBET). The theoretical results revealed that the retardation extent of boundary displacment, viz., the RMRB value, was as a function of protein content. Thus, the RMRB value of a sample could be used to determine its total protein content according to the relevant calibration curve. To demonstrate the concept and theoretical results, a novel microdevice was designed for the relevant experiments of MRBET. The microdevice has 30 identical work cells, each of which is composed of five ultrashort single microchannels (5 mm). In the microdevice, fluorescein isothiocyanate (FITC) was used to denote MRB motion and RMRB value for the first time, the polyacrylamide gel (PAG) containing protein sample was photopolymerized in microchannels, and the MRB was created with acid or alkali and target protein sample. As compared to the classic Kjeldahl method and conventional MRBET performed in glass tube, the developed titration chip has the following merits: good sensitivity (0.3-0.4 μg/mL vs 150-200 μg/mL of protein concentration, 0.6-0.8 ng vs 30-2000 μg of absolute protein content), rapid analysis (20-60 s vs 15-200 min), and portable low-power (15 V vs 200 V).

  8. Sensitive liquid chromatography-tandem mass spectrometry method for the simultaneous determination of paracetamol and guaifenesin in human plasma.

    Science.gov (United States)

    Chen, Xiaoyan; Huang, Jia; Kong, Zhang; Zhong, Dafang

    2005-03-25

    A rapid and sensitive method for the simultaneous determination of paracetamol and guaifenesin in human plasma was developed and validated, using high-performance liquid chromatographic separation with tandem mass spectrometric detection. After extracted from plasma samples by diethyl ether-dichloromethane (3:2, v/v), the analytes and internal standard osalmide were chromatographed on a C18 column. Detection was performed on a triple quadrupole tandem mass spectrometer by selected reaction monitoring (SRM) mode via atmospheric pressure chemical ionization (APCI). The method was linear in the concentration range of 0.05-20.0 microg/ml for paracetamol and 5.0-2000.0 ng/ml for guaifenesin. The intra- and inter-day precision was within 14% for both paracetamol and guaifenesin. The assay accuracy was within +/-2.4% for the analytes. This is the first assay method described for the simultaneous determination of paracetamol and guaifenesin in plasma using one chromatographic run. The method was successfully employed in a pharmacokinetic study after an oral administration of a multicomponent formulation, containing 650 mg paracetamol, 200 mg guaifenesin, 60 mg pseudoephedrine and 20 mg dextrorphan.

  9. Label-free and sensitive aptasensor based on dendritic gold nanostructures on functionalized SBA-15 for determination of chloramphenicol.

    Science.gov (United States)

    Bagheri Hashkavayi, Ayemeh; Raoof, Jahan Bakhsh; Azimi, Razieh; Ojani, Reza

    2016-04-01

    A highly sensitive and low-cost electrochemical aptasensor was developed for the determination of chloramphenicol (CAP). The system was based on a CAP-binding aptamer, a molecular recognition element, and 1,4-diazabicyclo[2.2.2]octane (DABCO)-supported mesoporous silica SBA-15 on the surface of a screen-printed graphite electrode for formation of dendritic gold nanostructures and improving the performance and conductivity of the biosensor. Hemin has been applied as an electrochemical indicator which interacted with the guanine bases of the aptamer. In the absence of CAP, hemin binds to the aptamer and produces a weak differential pulse voltammetric (DPV) signal. The presence of CAP led to stabilization of the folded aptamer, which generated an amplified DPV signal. The peak current of hemin increased linearly with the concentration of CAP. Under optimal conditions, two linear ranges were obtained from 0.03 to 0.15 μM and 0.15 to 7.0 μM, respectively, and the detection limit was 4.0 nM. The prepared biosensor has good selectivity against other non-target drugs. Thus, the sensor could provide a promising platform for the fabrication of aptasensors. The feasibility of using this aptasensor was demonstrated by determination of CAP in a human blood serum sample.

  10. A rapid and sensitive resonance Rayleigh scattering spectra method for the determination of quinolones in human urine and pharmaceutical preparation.

    Science.gov (United States)

    Qiao, Man; Wang, Yaqiong; Liu, Shaopu; Liu, Zhongfang; Yang, Jidong; Zhu, Jinghui; Hu, Xiaoli

    2015-03-01

    A new method based on resonance Rayleigh scattering (RRS) was proposed for the determination of quinolones (QNS) at the nanogram level. In pH 3.3-4.4 Britton-Robinson buffer medium, quinolones such as ciprofloxacin, pipemidic acid (PIP), lomefloxacin (LOM), norfloxacin (NOR) and sarafloxacin (SAR) were protonated and reacted with methyl orange (MO) to form an ion-pair complex, which then further formed a six-membered ring chelate with Pd(II). As a result, new RRS spectra appeared and the RRS intensities were enhanced greatly. RRS spectral characteristics of the MO-QNS-Pd(II) systems, the optimum conditions for the reaction, and the influencing factors were investigated. Under optimum conditions, the scattering intensity (∆I) increments were directly proportional to the concentration of QNS with in certain ranges. The method had high sensitivity, and the detection limits (3σ) ranged from 6.8 to 12.6 ng/mL. The proposed method had been successfully applied for the determination of QNS in pharmaceutical formulations and human urine samples. In addition, the mechanism of the reaction system was discussed based on IR, absorption and fluorescence spectral studies. The reasons for the enhancement of scattering spectra were discussed in terms of fluorescence-scattering resonance energy transfer, hydrophobicity and molecular size.

  11. Sensitive electrochemical determination of miRNAs based on a sandwich assay onto magnetic microcarriers and hybridization chain reaction amplification.

    Science.gov (United States)

    Torrente-Rodríguez, R M; Campuzano, S; Montiel, V Ruiz-Valdepeñas; Montoya, J J; Pingarrón, J M

    2016-12-15

    A novel electrochemical approach for determination of miRNAs involving a sandwich hybridization assay onto streptavidin-magnetic beads (Strep-MBs), hybridization chain reaction (HCR) amplification and amperometric detection at disposable screen-printed carbon electrodes is reported. Using miRNA-21 as the target analyte, a dynamic linear range from 0.2 to 5.0nM with a 60pM (1.5fmol in 25μL) detection limit was obtained. The achieved sensitivity is 24-fold higher than a non-HCR amplification approach involving conventional sandwich type assay onto MBs. Moreover, the whole assay time lasted 1h 45min which is remarkably shorter than other reported methodologies. The methodology exhibited full selectivity against other non-complementary miRNAs as well as an acceptable discrimination between homologous miRNA family members. The applicability of this novel approach was demonstrated by determining mature miRNA-21 in total RNA (RNAt) extracted from tumor cells and human tissues.

  12. Sensitive voltammetric determination of lead released from ceramic dishes by using of bismuth nanostructures anchored on biochar.

    Science.gov (United States)

    Agustini, Deonir; Mangrich, Antonio Salvio; Bergamini, Márcio F; Marcolino-Junior, Luiz Humberto

    2015-09-01

    A simple and sensitive electroanalytical method was developed for determination of nanomolar levels of Pb(II) based on the voltammetric stripping response at a carbon paste electrode modified with biochar (a special charcoal) and bismuth nanostructures (nBi-BchCPE). The proposed methodology was based on spontaneous interactions between the highly functionalized biochar surface and Pb(II) ions followed by reduction of these ions into bismuth nanodots which promote an improvement on the stripping anodic current. The experimental procedure could be summarized in three steps: including an open circuit pre-concentration, reduction of accumulated lead ions at the electrode surface and stripping step under differential pulse voltammetric conditions (DPAdSV). SEM images revealed dimensions of bismuth nanodots ranging from 20 nm to 70 nm. The effects of main parameters related to biochar, bismuth and operational parameters were examined in detail. Under the optimal conditions, the proposed sensor has exhibited linear range from 5.0 to 1000 nmol L(-1) and detection limit of 1.41 nmol L(-1) for Pb(II). The optimized method was successfully applied for determination of Pb(II) released from overglaze-decorated ceramic dishes. Results obtained were compared with those given by inductively coupled plasma optical emission spectroscopy (ICP-OES) and they are in agreement at 99% of confidence level. Copyright © 2015. Published by Elsevier B.V.

  13. Simple and sensitive spectrofluorimetric method for the determination of oseltamivir phosphate in capsules through derivatization with fluorescamine.

    Science.gov (United States)

    Aydoğmuş, Zeynep

    2009-07-01

    A new, simple and sensitive spectrofluorimetric method has been developed for the determination of oseltamivir phosphate (OSP) in capsules. The method is based on the reaction between oseltamivir and fluorescamine in borate buffer solution of pH 8.50 to give highly fluorescent derivatives that are measured at 483 nm using an excitation wavelength of 381. The different experimental parameters effecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence intensity concentration plot is rectilinear over the range 50-450 ng mL(-1) with a lower detection limit (LOD) of 1.219 ng mL(-1) and limit of quantitation (LOQ) of 4.064 ng mL(-1). Selectivity was validated by subjecting stock solution of OSP to acidic, basic, oxidative, and thermal degradation. No interference was observed from excipients present in formulations. The developed method was successfully applied to determination of the drug in capsules. The mean % recovery (n = 6) was 100.08. The results obtained were in good agreement with those obtained using a reported spectrophotometric method.

  14. A sensitive and selective molecularly imprinted sensor combined with magnetic molecularly imprinted solid phase extraction for determination of dibutyl phthalate.

    Science.gov (United States)

    Zhang, Zhaohui; Luo, Lijuan; Cai, Rong; Chen, Hongjun

    2013-11-15

    A highly sensitive and selective molecularly imprinted (MIP) sensor combined with magnetic molecularly imprinted solid phase extraction (MMISPE) was developed for the determination of dibutyl phthalate (DBP) in complex matrixes. The magnetic molecularly imprinted polymer (MMIP) was synthesized as solid phase extraction (SPE) sorbet to extract DBP from complex matrixes and as sensing element to improve the selectivity of the imprinted sensor. The morphologies of MMIP and MIP-sensor were characterized by using scanning electron microscope (SEM) and transmission electron microscopy (TEM). The electrochemical performances of MIP-sensor were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The conditions of preconcentration, elution and electrochemical determination were studied in detail. Under the optimized experimental conditions, the response currents of the MIP-sensor exhibited a linear relationship towards DBP concentrations ranging from 1.0 × 10(-8)g/L to 1.0 × 10(-3)g/L. The limit of detection of the MMIP-sensor coupled with the MMISPE was calculated as 0.052 ng/L. The MMIP-sensor coupled with the MMISPE was applied to detect DBP in complex samples successfully.

  15. A SIMPLE AND-SENSITIVE STABILITY-INDICATING UHPLC-DAD METHOD FOR THE DETERMINATION OF CEFETAMET PIVOXIL HYDROCHLORIDE.

    Science.gov (United States)

    Garbacki, Piotr; Cielecka-Piontek, Judyta; Zalewski, Przemysław; Oszczapowicz, Irena; Jelińska, Anna

    2016-01-01

    A fast and sensitive UHPLC-DAD method was developed and subsequently validated for determination of cefetamet pivoxil hydrochloride in the presence of its degradation products. The chromatographic separation was carried out on a Waters Acquity BEH C18, (2.1 x 100 mm, 1.7 µm) column. The mobile phase was composed of 0.1% formic acid and acetonitrile (40 : 60, v/v) at the flow rate 0.7 mL/min. The detection wavelength was 265 nm and the temperature was 30 °C. Cefetamet pivoxil hydrochloride was susceptible to degradation under the influence of sodium hydroxide, hydrochloric acid and in the conditions of increased temperature and relative humidity. However, it was stable after irradiation, in increased temperature in dry air and in the presence of oxidizing agent. The developed UHPLC-DAD method was linear over the concentration range of 10-240 µg/mL (r2 = 0.9999; n = 12). The obtained RSD values were less than 2%, demonstrating that the described procedure is precise. The accuracy was also confirmed (mean recoveries were 97.79-102.08%). Under applied chromatographic conditions LOD and LOQ values were 2.08 mg/mL and 6.29 mg/mL, respectively. The proposed method was successfully applied in determination of cefetamet pivoxil hydrochloride in aqueous solutions as well as in the solid state.

  16. High sensitive and selective HPTLC method assisted by digital image processing for simultaneous determination of catecholamines and related drugs.

    Science.gov (United States)

    Sima Tuhuţiu, Ioana Anamaria; Casoni, Dorina; Sârbu, Costel

    2013-09-30

    A highly sensitive and selective thin layer chromatographic (TLC) method was developed for simultaneous determination of catecholamines and their related drugs using a new detection method and digital image processing of chromatographic plates. For the quantitative evaluation of the investigated compounds, the chromatographic separation was followed by spraying the plate with 0.02% solution of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) in ethanol. The BioDit Thin Layer Chromatography (TLC) Scanner device and advanced specific software (ImageDecipher-TLC, Sorbfil TLC Videodensitometer and JustTLC) were used for the detection and quantification of chromatographic spots. For an accurate determination, the RGB colored images of the bright-white spots detected against a purple background were inverted and processed after their conversion into green scale. The results showed a strongly linear correlation between area (R(2)>0.99) and volume (R(2)>0.99) of spots and concentration of investigated compounds in all cases. The limit of detection (LOD) and the limit of quantification (LOQ) were below 49.3 ng/spot and 69.6 ng/spot respectively in all cases. The evaluation of the method was performed using different pharmaceutical samples spiked with the investigated amines and validated with respect to accuracy and precision.

  17. Epithelial-stromal interactions in human breast cancer: effects on adhesion, plasma membrane fluidity and migration speed and directness.

    Directory of Open Access Journals (Sweden)

    Cristiana Angelucci

    Full Text Available Interactions occurring between malignant cells and the stromal microenvironment heavily influence tumor progression. We investigated whether this cross-talk affects some molecular and functional aspects specifically correlated with the invasive phenotype of breast tumor cells (i.e. adhesion molecule expression, membrane fluidity, migration by co-culturing mammary cancer cells exhibiting different degrees of metastatic potential (MDA-MB-231>MCF-7 with fibroblasts isolated from breast healthy skin (normal fibroblasts, NFs or from breast tumor stroma (cancer-associated fibroblasts, CAFs in 2D or 3D (nodules cultures. Confocal immunofluorescence analysis of the epithelial adhesion molecule E-cadherin on frozen nodule sections demonstrated that NFs and CAFs, respectively, induced or inhibited its expression in MCF-7 cells. An increase in the mesenchymal adhesion protein N-cadherin was observed in CAFs, but not in NFs, as a result of the interaction with both kinds of cancer cells. CAFs, in turn, promoted N-cadherin up-regulation in MDA-MB-231 cells and its de novo expression in MCF-7 cells. Beyond promotion of "cadherin switching", another sign of the CAF-triggered epithelial-mesenchymal transition (EMT was the induction of vimentin expression in MCF-7 cells. Plasma membrane labeling of monolayer cultures with the fluorescent probe Laurdan showed an enhancement of the membrane fluidity in cancer cells co-cultured with NFs or CAFs. An increase in lipid packing density of fibroblast membranes was promoted by MCF-7 cells. Time-lapsed cell tracking analysis of mammary cancer cells co-cultured with NFs or CAFs revealed an enhancement of tumor cell migration velocity, even with a marked increase in the directness induced by CAFs.Our results demonstrate a reciprocal influence of mammary cancer and fibroblasts on various adhesiveness/invasiveness features. Notably, CAFs' ability to promote EMT, reduction of cell adhesion, increase in membrane fluidity, and

  18. Assessing manganese nanostructures based carbon nanotubes composite for the highly sensitive determination of vitamin C in pharmaceutical formulation.

    Science.gov (United States)

    Hameed, Sadaf; Munawar, Anam; Khan, Waheed S; Mujahid, Adnan; Ihsan, Ayesha; Rehman, Asma; Ahmed, Ishaq; Bajwa, Sadia Z

    2017-03-15

    This work is the first report describing the development of a novel three dimensional manganese nanostructures based carbon nanotubes (CNTs-Mn NPs) composite, for the determination of ascorbic acid (vitamin C) in pharmaceutical formulation. Carbon nanotubes (CNTs) were used as a conductive skeleton to anchor highly electrolytic manganese nanoparticles (Mn NPs), which were prepared by a hydrothermal method. Scanning electron microscopy and atomic force microscopy revealed the presence of Mn Nps of 20-25nm, anchored along the whole length of CNTs, in the form of patches having a diameter of 50-500nm. Fourier transform infrared spectroscopy confirmed the surface modification of CNTs by amine groups, whereas dynamic light scattering established the presence of positive charge on the prepared nanocomposite. The binding events were studied by monitoring cyclic voltammetry signals and the developed nanosensor exhibited highly sensitive response, demonstrating improved electrochemical activity towards ascorbic acid. Linear dependence of the peak current on the square root of scan rates (R(2)=0.9785), demonstrated that the oxidation of ascorbic acid by the designed nanostructures is a diffusion control mechanism. Furthermore, linear range was found to be 0.06-4.0×10(-3)M, and nanosensor displayed an excellent detection limit of 0.1µM (S/N=3). This developed nanosensor was successfully applied for the determination of vitamin C in pharmaceutical formulation. Besides, the results of the present study indicate that such a sensing platform may offer a different pathway to utilize manganese nanoparticles based CNTs composite for the determination of other bio-molecules as well.

  19. 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.

  20. The lignan, (-)-sesamin reveals cytotoxicity toward cancer cells: pharmacogenomic determination of genes associated with sensitivity or resistance.

    Science.gov (United States)

    Saeed, Mohamed; Khalid, Hassan; Sugimoto, Yoshikazu; Efferth, Thomas

    2014-04-15

    (-)-Sesamin is a lignan present in sesam oil and a number of medicinal plants. It exerts various pharmacological effects, such as prevention of hyperlipidemia, hypertension, and carcinogenesis. Moreover, (-)-sesamin has chemopreventive and anticancer activity in vitro and in vivo. Multidrug resistance (MDR) of tumors leads to fatal treatment outcome in many patients and novel drugs able to kill multidrug-resistant cells are urgently needed. P-glycoprotein (MDR1/ABCB1) is the best known ATP-binding cassette (ABC) drug transporter mediating MDR. ABCB5 is a close relative to ABCB1, which also mediates MDR. We found that the mRNA expressions of ABCB1 and ABCB5 were not related to the 50% inhibition concentrations (IC50) for (-)-sesamin in a panel of 55 cell lines of the National Cancer Institute, USA. Furthermore, (-)-sesamin inhibited ABCB1- or ABCB5-overexpressing cells with similar efficacy than their drug-sensitive parental counterparts. In addition to ABC transporter-mediated MDR, we attempted to identify other molecular determinants of (-)-sesamin resistance. For this reason, we performed COMPARE and hierarchical cluster analyses of the transcriptome-wide microarray-based mRNA expression of the NCI cell panel. Twenty-three genes were identified, whose mRNA expression correlated with the IC50 values for (-)-sesamin. These genes code for proteins of different biological functions, i.e. ribosomal proteins, components of the mitochondrial respiratory chain, proteins involved in RNA metabolism, protein biosynthesis, or glucose and fatty acid metabolism. Subjecting this set of genes to cluster analysis showed that the cell lines were assembled in the resulting dendrogram according to their responsiveness to (-)-sesamin. In conclusion, (-)-sesamin is not involved in MDR mediated by ABCB1 or ABCB5 and may be valuable to bypass chemoresistance of refractory tumors. The microarray expression profile, which predicted sensitivity or resistance of tumor cells to (-)-sesamin

  1. A fast and sensitive method for the determination of nitrite in human plasma by capillary electrophoresis with fluorescence detection.

    Science.gov (United States)

    Wang, Xu; Adams, Erwin; Van Schepdael, Ann

    2012-08-15

    Analysis of nitrite, the indicator of nitric oxide (NO) generation in vivo, provides a useful tool to study NO synthesis in vivo. A fast and sensitive fluorometric CE method was developed for determination of nitrite in human plasma through its derivatization with 2,3-diaminonaphthalene (DAN). Nitrite in human plasma was easily reacted with DAN under acid conditions to yield the highly fluorescent 2,3-naphthotriazole (NAT). Fluorescence detection was optimized to achieve subnanomolar detection which allows a direct analysis of plasma samples unlike most CE-UV methods using sample stacking. Acetonitrile was used to remove the protein. Short-end injection and a high voltage (-30 kV) were used to shorten the analysis time. The good separation was achieved with 20 mM borate buffer at pH 9.23. The separation of NAT was obtained within 1.4 min. The deproteinized plasma sample was injected hydrodynamically for 5s at -50 mbar into a 60 cm × 75 μm internal diameter uncoated fused-silica capillary. Excitation wavelength was selected with a broad-band filter (240-400 nm), and the emitted light was measured at 418 nm by the use of a cutoff filter. A good linearity (R(2)=0.9975) was obtained in the range from 2 to 500 nM. The detection limit of nitrite was 0.6 nM in original plasma samples, which is 750 times lower than our previous CE-UV method. The developed fluorometric CE method offers the advantages of more simple system and lower cost compared with the current fluorometric HPLC methods without losing sensitivity. The detected mean nitrite concentration in human plasma by this method was consistent with the most frequently reported values.

  2. Highly sensitive determination of fatty acid esters of hydroxyl fatty acids by liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Zhu, Quan-Fei; Yan, Jing-Wen; Gao, Yang; Zhang, Jing-Wei; Yuan, Bi-Feng; Feng, Yu-Qi

    2017-09-01

    Recently, a new class of endogenous lipids, branched fatty acid esters of hydroxy fatty acids (FAHFAs), was discovered with anti-diabetic and anti-inflammatory effects in mammals. FAHFAs attracted increasing attention because of their critical physiological function. However, accurate quantitation of FAHFAs is still a challenge due to their high structure similarity and low abundance in biological samples. Herein, we developed a highly sensitive method for the determination of 16 FAHFAs (PAHSAs, OAHSAs, SAHSAs and POHSAs) in biological samples by coupling strong anion exchange solid phase extraction (SAX-SPE) with chemical labeling assisted ultra-high performance liquid chromatography/mass spectrometry (SAX-SPE-CL-UHPLC/MS). In the developed method, SAX-SPE was employed to selectively enrich and purify FAHFAs from biological samples. And then a pair of isotope labeling reagents, 2-dimethylaminoethylamine (DMED) and d4-DMED were used to label the purified samples and standard FAHFAs, respectively. The labeled samples were mixed and further subjected to UHPLC/MS analysis. Our results demonstrated that the detection sensitivities of FAHFAs increased by 7-72 folds upon DMED labeling and the limits of detections (LODs) of labeled FAHFAs ranged from 0.01 to 0.14pg. Moreover, a good separation of FAHFAs isomers was achieved on C18 column in a UHPLC system and all FAHFAs could be analyzed in 20min with sharp peak shape. The established method provided substantial sensitivity, high specificity, and broad linear dynamic range (3 orders of magnitude). Using this method, we successfully measured the contents and distribution of FAHFAs in rat white adipose, lung, kidney, thymus, liver and heart tissues. The results showed that 7 FAHFAs (13-, 12-, 9-, 5-PAHSA, 13-, 12- and 9-SAHSA) were observed in different tissues of rat. In addition, we successfully detected the above 7 FAHFAs in human serum samples; and among the 7 FAHFAs, 13-, 9-PAHSA, 13- and 12-SAHSA were found remarkably

  3. 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.

  4. Supplementation of iron alone and combined with vitamins improves haematological status, erythrocyte membrane fluidity and oxidative stress in anaemic pregnant women

    NARCIS (Netherlands)

    Aiguo, M.; Schouten, E.G.; Ye Sun, Yong; Yang, Fang; Xia Han, Xiu; Zhi Zhang, Feng; Chen Jiang, D.; Kok, F.J.

    2010-01-01

    Pregnancy is a condition exhibiting increased susceptibility to oxidative stress, and Fe plays a central role in generating harmful oxygen species. The objective of the present study is to investigate the changes in haematological status, oxidative stress and erythrocyte membrane fluidity in anaemic

  5. Fluidity evaluation of cell membrane model formed on graphene oxide with single particle tracking using quantum dot

    Science.gov (United States)

    Okamoto, Yoshiaki; Motegi, Toshinori; Iwasa, Seiji; Sandhu, Adarsh; Tero, Ryugo

    2015-04-01

    The lipid bilayer is the fundamental structure of plasma membranes, and artificial lipid bilayer membranes are used as model systems of cell membranes. Recently we reported the formation of a supported lipid bilayer (SLB) on graphene oxide (GO) by the vesicle fusion method. In this study, we conjugated a quantum dot (Qdot) on the SLB surface as a fluorescence probe brighter than dye-labeled lipid molecules, to qualitatively evaluate the fluidity of the SLB on GO by the single particle tracking method. We obtained the diffusion coefficient of the Qdot-conjugated lipids in the SLB on GO. We also performed the Qdot conjugation on the SLB containing a lipid conjugated with polyethylene glycol, to prevent the nonspecific adsorption of Qdots. The difference in the diffusion coefficients between the SLBs on the GO and the bare SiO2 regions was evaluated from the trajectory of single Qdot-conjugated lipid diffusing between the two regions.

  6. Correlation between ionic conductivity and fluidity of polymer gel electrolytes containing NH4CF3SO3

    Indian Academy of Sciences (India)

    Harinder Pal Singh; Rajiv Kumar; S S Sekhon

    2005-08-01

    Nonaqueous polymer gel electrolytes containing ammonium triflate (NH4CF3SO3) and dimethylacetamide (DMA) with polymethylmethacrylate (PMMA) as the gelling polymer have been synthesized which show high value of conductivity (∼ 10-2 S/cm) at 25°C. The conductivity of polymer gel electrolytes containing different concentrations of NH4CF3SO3 shows a small decrease with the addition of PMMA and this has been correlated with the variation of fluidity of these gel electrolytes. The small decrease in conductivity with PMMA addition shows that polymer plays the role of stiffener and this is supported by FTIR results which also indicates the absence of any active interaction between polymer and NH4CF3SO3 in these gel electrolytes.

  7. Intestinal D-glucose transport and membrane fluidity along crypt-villus axis of streptozocin-induced diabetic rats.

    Science.gov (United States)

    Dudeja, P K; Wali, R K; Klitzke, A; Brasitus, T A

    1990-10-01

    Diabetes was induced in male Lewis rats by a single injection of streptozocin (50 mg/kg body wt ip). After 10-14 days, diabetic and age- and sex-matched control animals were killed, and their proximal small intestines were removed. Villus-tip, mid-villus, and lower-villus enterocytes were harvested from each group with a method that combined divalent cation chelation with mild mechanical dissociation. These fractions were used as starting material to prepare brush-border membrane vesicles. Preparations from each of these fractions were then analyzed and compared with respect to their Na(+)-gradient-dependent and Na(+)-independent D-glucose transport, lipid fluidity, and lipid composition. The results of these experiments demonstrated that 1) maximum rates of Na(+)-gradient-dependent D-glucose transport (Vmax) were greatest in membrane vesicles prepared from mature cells (villus tip and mid villus) of control rats; 2) the glucose concentration producing half-maximal rates of transport (Km), however, was significantly lower in lower-villus membrane vesicles of control rats, suggesting that a distinct glucose transporter existed in the membranes of these relatively immature enterocytes; 3) Na(+)-gradient-dependent, but not Na(+)-independent, D-glucose uptake was greater in diabetic membrane vesicles prepared from mid-villus and lower-villus fractions but not in vesicles prepared from villus-tip cells; and 4) no obvious relationship between alterations in membrane lipid fluidity and enhanced uptake of Na(+)-gradient-dependent D-glucose by these transporter(s) could be established in this experimental model of acute diabetes mellitus.

  8. Sex hormones alter sex ratios in the Indian skipper frog, Euphlyctis cyanophlyctis: Determining sensitive stages for gonadal sex reversal.

    Science.gov (United States)

    Phuge, S K; Gramapurohit, N P

    2015-09-01

    In amphibians, although genetic factors are involved in sex determination, gonadal sex differentiation can be modified by exogenous steroid hormones suggesting a possible role of sex steroids in regulating the process. We studied the effect of testosterone propionate (TP) and estradiol-17β (E2) on gonadal differentiation and sex ratio at metamorphosis in the Indian skipper frog, Euphlyctis cyanophlyctis with undifferentiated type of gonadal differentiation. A series of experiments were carried out to determine the optimum dose and sensitive stages for gonadal sex reversal. Our results clearly indicate the importance of sex hormones in controlling gonadal differentiation of E. cyanophlyctis. Treatment of tadpoles with 10, 20, 40, and 80μg/L TP throughout larval period resulted in the development of 100% males at metamorphosis at all concentrations. Similarly, treatment of tadpoles with 40μg/L TP during ovarian and testicular differentiation resulted in the development of 90% males, 10% intersexes and 100% males respectively. Treatment of tadpoles with 10, 20, 40, and 80μg/L E2 throughout larval period likewise produced 100% females at all concentrations. Furthermore, exposure to 40μg/L E2 during ovarian and testicular differentiation produced 95% females, 5% intersexes and 91% females, 9% intersexes respectively. Both TP and E2 were also effective in advancing the stages of gonadal development. Present study shows the effectiveness of both T and E2 in inducing complete sex reversal in E. cyanophlyctis. Generally, exposure to E2 increased the larval period resulting in significantly larger females than control group while the larval period of control and TP treated groups was comparable. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. 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 (HRshighest-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.

  10. Development of a Method for a Sensitive Simultaneous Determination of Dopamine and Paracetamol in Biological Samples and Pharmaceutical Preparations

    Directory of Open Access Journals (Sweden)

    Ali Babaei

    2011-01-01

    Full Text Available A chemically modified electrode is constructed based on multiwalled carbon nanotube—modified glassy carbon electrode (MWCNTs/GCE. The measurements were carried out by application of differential pulse voltammetry (DPV, cyclic voltammetry (CV, and chronoamperometry (CA methods. Application of DPV method showed wide linear range of DA from 1 μM to 540 μM and a detection limit of 0.098 μM (S/N=3. The linear range of PAR of 3 μM to 300 μM and a detection limit of 0.15 μM, were obtained. The modified electrode showed electrochemical responses with high sensitivity, high selectivity, and excellent stability for DA and PAR determination at optimal conditions, which makes it a suitable sensor for simultaneous submicromolar detection of DA and PAR in solutions. The analytical performance of this sensor has been evaluated for detection of DA and PAR in human serum, human urine, and pharmaceutical preparation with satisfactory results.

  11. Rapid and Sensitive Determination of Timosaponin AIII in Rat Plasma by LC-MS/MS and Its Pharmacokinetic Application

    Science.gov (United States)

    Liu, Yanping; Pu, Yiqiong; Zhang, Tong; Ding, Yue; Wang, Bing; Cai, Zhenzhen

    2013-01-01

    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. PMID:23434663

  12. 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.

  13. An additional S-shaped structure for sensitivity improvement of coaxial probe for permittivity determination of low loss materials

    Science.gov (United States)

    Jiao, Xingmin; Jin, Wei; Yang, Xiaoqing

    2015-05-01

    Permittivity measurement of materials is important in microwave chemistry, microwave material processing and microwave heating. The open-ended coaxial line method is one of the most popular and effective means for permittivity measurement. However, the conventional coaxial probe has difficulty in distinguishing small permittivity variations for low loss media. In this paper an additional S-shaped structure is proposed for sensitivity improvement of a coaxial probe for permittivity determination of low loss materials at 2.45 GHz. The small permittivity variation can be distinguished due to field enhancement generated by the additional S-shaped structure. We studied the variation of reflection coefficient amplitude for three kinds of samples with different moisture content, within the probe at different insertion depths. We find that the conventional coaxial probe cannot distinguish small permittivity variations until the moisture content of materials reaches 3%. Meanwhile, the probe with the S-shaped structure can detect such small permittivity variations when the moisture content of samples changes by only 1%. The experimental results demonstrate that the new probe proposed in this paper is reliable and feasible.

  14. Comparison of specificity and sensitivity of immunochemical and molecular techniques for determination of Clavibacter michiganensis subsp. michiganensis.

    Science.gov (United States)

    Kokosková, B; Mráz, I; Fousek, J

    2010-05-01

    Detection of Clavibacter michiganensis subsp. michiganensis (Cmm), causing bacterial canker of tomato, was verified using PTA-ELISA and IFAS with PAbs of Neogen Europe Ltd. (UK), and with published and also laboratory-generated PCR primers from the Cmm tomatinase gene. The specificity of this technique was determined with 15 plant-pathogenic and 4 common, saprophytic bacteria. With IFAS, crossreactions were found for Pantoea dispersa, P. agglomerans and Rahnella aquatilis, and with PTA-ELISA for Curtobacterium flaccumfaciens, Pectobacterium atrosepticum and Dickeya sp. Cross-reactions with subspecies other than michiganensis were also found using both methods. Molecular methods were optimized by verification of annealing temperatures and times for both primers. Conditions were finally adjusted to 30 s at 65 degrees C for Dreier's and 10 s at 69 degrees C for our primer set. After this optimization, both primer pairs produced positive reaction only with Cmm. By means of PTA-ELISA and IFAS, Cmm strains were detected at a concentration up to 10(5) CFU/mL and 10(3) CFU/mL, respectively. The PCR test with bacterial cell suspensions reached a sensitivity of 10(3) CFU/mL with our designed primers and 104 CFU/mL with Dreier's primer pair.

  15. 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.

  16. Determining sensitive stages for learning to detect predators in larval bronzed frogs: Importance of alarm cues in learning

    Indian Academy of Sciences (India)

    Anuradha Batabyal; Sachin M Gosavi; Narahari P Gramapurohit

    2014-09-01

    Successful survival and reproduction of prey organisms depend on their ability to detect their potential predators accurately and respond effectively with suitable defences. Predator detection can be innate or can be acquired through learning.We studied prey–predator interactions in the larval bronzed frogs (Sylvirana temporalis), which have the innate ability to detect certain predators. We conducted a series of experiments to determine if the larval S. temporalis rely solely on innate predator detection mechanisms or can also learn to use more specific cues such as conspecific alarm cues for the purpose. The results of our study clearly indicate that larval S. temporalis use both innate and learned mechanisms for predator detection. Predator-naïve tadpoles could detect kairomones alone as a potential threat and responded by reducing activity, suggesting an innate predator detection mechanism. Surprisingly, predator-naïve tadpoles failed to detect conspecific alarm cues as a potential threat, but learned to do so through experience. After acquiring the ability to detect conspecific alarm cues, they could associate novel predator cues with conspecific alarm cues. Further, post feeding stages of larval S. temporalis are sensitive for learning to detect conspecific alarm cues to label novel predators.

  17. Application of a Cu-chitosan/multiwalled carbon nanotube film-modified electrode for the sensitive determination of rutin.

    Science.gov (United States)

    Gholivand, Mohammad Bagher; Mohammadi-Behzad, Leila; Hosseinkhani, Hossein

    2016-01-15

    A new sensitive electrochemical sensor, a glassy carbon electrode modified with chemically cross-linked copper-complexed chitosan/multiwalled carbon nanotubes (Cu-CS/MWCNT/GCE), for rutin analysis was constructed. Experimental investigations of the influence of several parameters showed that the rutin can effectively accumulate on the surface of the Cu-CS/MWCNT/GCE, which accumulation caused a pair of well-defined redox peaks in the electrochemical signal when measurements were carried out in Britton-Robinson buffer solution (pH 3, 0.04 M). The surface of the Cu-CS/MWCNT/GCE was characterized by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry analysis. In a rutin concentration range of 0.05-100 μM and under optimized conditions, a linear relationship between the oxidation peak current of rutin and its concentration was obtained with a detection limit of 0.01 μM. The Cu-CS/MWCNT/GCE showed good selectivity, stability, and reproducibility. Moreover, the sensor was used to determine the presence of rutin in fruits with satisfactory results.

  18. Visual sensitivity is a stronger determinant of illusory processes than auditory cue parameters in the sound-induced flash illusion.

    Science.gov (United States)

    Kumpik, Daniel P; Roberts, Helen E; King, Andrew J; Bizley, Jennifer K

    2014-06-24

    The sound-induced flash illusion (SIFI) is a multisensory perceptual phenomenon in which the number of brief visual stimuli perceived by an observer is influenced by the number of concurrently presented sounds. While the strength of this illusion has been shown to be modulated by the temporal congruence of the stimuli from each modality, there is conflicting evidence regarding its dependence upon their spatial congruence. We addressed this question by examining SIFIs under conditions in which the spatial reliability of the visual stimuli was degraded and different sound localization cues were presented using either free-field or closed-field stimulation. The likelihood of reporting a SIFI varied with the spatial cue composition of the auditory stimulus and was highest when binaural cues were presented over headphones. SIFIs were more common for small flashes than for large flashes, and for small flashes at peripheral locations, subjects experienced a greater number of illusory fusion events than fission events. However, the SIFI was not dependent on the spatial proximity of the audiovisual stimuli, but was instead determined primarily by differences in subjects' underlying sensitivity across the visual field to the number of flashes presented. Our findings indicate that the influence of auditory stimulation on visual numerosity judgments can occur independently of the spatial relationship between the stimuli. © 2014 ARVO.

  19. Influence of blood collection systems on the prothrombin time and international sensitivity index determined with human and rabbit thromboplastin reagents.

    Science.gov (United States)

    van den Besselaar, Anton M H P; Hoekstra, Martha M C L; Witteveen, Evelina; Didden, Jan H; van der Meer, Felix J M

    2007-05-01

    Three brands of blood collection tubes were studied for their influence on the prothrombin time (PT) and international sensitivity index (ISI) for 5 commercial thromboplastin reagents. With all reagents, PTs were shorter in Vacutainer (Becton Dickinson Vacutainer Systems, Plymouth, England) samples than in S-Monovette (Sarstedt, Nümbrecht, Germany) or Venosafe (Terumo Europe, Leuven, Belgium) samples. ISI values were higher with Vacutainer samples than with S-Monovette or Venosafe samples. The ISI differences between the tubes were small for Thromborel-S (2.1%; Dade Behring, Marburg, Germany) and Hepato Quick (1.1%; Diagnostica Stago, Asnières, France; Roche Diagnostics Nederland, Almere, the Netherlands) but greater for Neoplastin Plus (5.5%; Diagnostica Stago; Roche Diagnostics Nederland), Simplastin HTF (8.3%; bioMérieux, Durham, NC), and Innovin (8.8%; Dade Behring). The PT and ISI differences between the tubes could be explained mostly by the effect of magnesium ion contamination in the sodium citrate solutions. When PT ratios were transformed into international normalized ratios (INRs) using crossover ISI (ie, samples collected with one type of tube and ISI determined with another collection system for the PT reagent), the differences in mean INRs could be approximately 10%. For ISI calibration of reference thromboplastins, blood collection tubes should be used with minimal divalent metal ion contamination of the citrate solution.

  20. 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.

  1. A temperature-sensitive phenotype of avian myeloblastosis virus: determinants that influence the production of viral mRNAs.

    Science.gov (United States)

    Schirm, S; Moscovici, G; Bishop, J M

    1990-01-01

    The oncogene v-myb of avian myeloblastosis virus is expressed from an mRNA that arises by splicing of the viral genome. In previous work, we described a mutant strain of avian myeloblastosis virus (tsAMV) that elicits temperature-sensitive transformation and suggested that the mutation affects production of the mRNA for v-myb. We now report that the principal determinant of the biochemical phenotype of tsAMV is a point mutation located in a crucial region of the splice acceptor site for v-myb mRNA. The mutation reduces v-myb mRNA production but could account for the conditional phenotype only in combination with an independent effect of temperature on the splicing of both wild-type and mutant viral RNAs, which we also describe here. Our findings dramatize the manner in which retroviruses normally control the splicing of their RNAs and implicate the sequence of the splice acceptor site in the control. Images PMID:2153241

  2. Determination of secondary ion mass spectrometry relative sensitivity factors for polar and non-polar ZnO

    Science.gov (United States)

    Laufer, Andreas; Volbers, Niklas; Eisermann, Sebastian; Potzger, Kay; Geburt, Sebastian; Ronning, Carsten; Meyer, Bruno K.

    2011-11-01

    Zinc oxide (ZnO) is regarded as a promising material for optoelectronic devices, due to its electronic properties. Solely, the difficulty in obtaining p-type ZnO impedes further progress. In this connection, the identification and quantification of impurities is a major demand. For quantitative information using secondary ion mass spectrometry (SIMS), so-called relative sensitivity factors (RSF) are mandatory. Such conversion factors did not yet exist for ZnO. In this work, we present the determined RSF values for ZnO using primary (ion implanted) as well as secondary (bulk doped) standards. These RSFs have been applied to commercially available ZnO substrates of different surface termination (a-plane, Zn-face, and O-face) to quantify the contained impurities. Although these ZnO substrates originate from the same single-crystal, we observe discrepancies in the impurity concentrations. These results cannot be attributed to surface termination dependent RSF values for ZnO.

  3. A sensitive determination of terbutaline in pharmaceuticals and urine samples using a composite electrode based on zirconium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet, E-mail: maslanoglu@harran.edu.tr

    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 (ZrO{sub 2}NPs). 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{sub 2}. The ZrO{sub 2}NPs/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{sub 2}NPs/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{sub 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{sub 2}NPs/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{sub 2} and MWCNTs. • The ZrO{sub 2}NPs/MWCNTs/GCE has greatly improved the voltammetry of terbutaline • The proposed electrode enabled a detection limit of 2.25 nM. • The proposed electrode

  4. 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

  5. Filter paper blood spot enzyme linked immunoassay for adiponectin and application in the evaluation of determinants of child insulin sensitivity.

    Directory of Open Access Journals (Sweden)

    Richard M Martin

    Full Text Available BACKGROUND: Adiponectin is an adipocyte-derived hormone that acts as a marker of insulin sensitivity. Bloodspot sampling by fingerstick onto filter paper may increase the feasibility of large-scale studies of the determinants of insulin sensitivity. We first describe the validation of an enzyme-linked immunoassay (ELISA for quantifying adiponectin from dried blood spots and then demonstrate its application in a large trial (PROBIT. METHODS: We quantified adiponectin from 3-mm diameter discs (≈3 µL of blood punched from dried blood spots obtained from: i whole blood standards (validation; and ii PROBIT trial samples (application in which paediatricians collected blood spots from 13,879 children aged 11.5 years from 31 sites across Belarus. We examined the distribution of bloodspot adiponectin by demographic and anthropometric factors, fasting insulin and glucose. RESULTS: In the validation study, mean intra-assay coefficients of variation (n=162 were 15%, 13% and 10% for 'low' (6.78 µg/ml, 'medium' (18.18 µg/ml and 'high' (33.13 µg/ml internal quality control (IQC samples, respectively; the respective inter-assay values (n=40 were 23%, 21% and 14%. The correlation coefficient between 50 paired whole bloodspot versus plasma samples, collected simultaneously, was 0.87 (95% CI: 0.78 to 0.93. Recovery of known quantities of adiponectin (between 4.5 to 36 µg/ml was 100.3-133%. Bloodspot adiponectin was stable for at least 30 months at -80°C. In PROBIT, we successfully quantified fasting adiponectin from dried blood spots in 13,329 of 13,879 (96% children. Mean adiponectin (standard deviation concentrations were 17.34 µg/ml (7.54 in boys and 18.41 µg/ml (7.92 in girls and were inversely associated with body mass index, fat mass, triceps and subscapular skin-fold thickness, waist circumference, height and fasting glucose. CONCLUSIONS: Bloodspot ELISA is suitable for measuring adiponectin in very small volumes of blood collected on filter paper

  6. New insights into shear-sensitivity in dinoflagellate microalgae.

    Science.gov (United States)

    Gallardo-Rodríguez, J J; López-Rosales, L; Sánchez-Mirón, A; García-Camacho, F; Molina-Grima, E; Chalmers, J J

    2016-01-01

    A modification of a flow contraction device was used to subject shear-sensitive microalgae to well-defined hydrodynamic forces. The aim of the study was to elucidate if the inhibition of shear-induced growth commonly observed in dinoflagellate microalgae is in effect due to cell fragility that results in cell breakage even at low levels of turbulence. The microalgae assayed did not show any cell breakage even at energy dissipation rates (EDR) around 10(12)Wm(-3), implausible in culture devices. Conversely, animal cells, tested for comparison purposes, showed high physical cell damage at average EDR levels of 10(7)Wm(-3). Besides, very short exposures to high levels of EDR promoted variations in the membrane fluidity of the microalgae assayed, which might trigger mechanosensory cellular mechanisms. Average EDR values of only about 4·10(5)Wm(-3) increased cell membrane fluidity in microalgae whereas, in animal cells, they did not.

  7. A rapid and sensitive method for determination of dimethyl benzoylphenyl urea in human plasma by using LC/MS/MS.

    Science.gov (United States)

    Zhao, Ming; Zabelina, Yelena; Rudek, Michelle A; Wolff, Antonio C; Baker, Sharyn D

    2003-11-24

    Dimethyl benzoylphenyl urea (BPU), a poorly water-soluble benzoylphenyl urea derivative, inhibits tubulin polymerization and causes microtubule depolymerization in vitro with activity against solid tumors. BPU is currently being tested in Phase I clinical trials. A rapid, sensitive and specific method using LC/MS/MS has been developed for the quantitation of BPU in human plasma to perform pharmacokinetic (PK) and pharmacodynamic (PD) studies of BPU administered orally once a week. BPU is extracted from plasma into acetonitrile-n-butylchloride and separated on a Waters X-Terra MS C18 (50 x 2.1 mm, 3.5 microm) column with acetonitrile/water mobile phase (80:20, v/v) containing 0.1% formic acid using isocratic flow at 0.15 ml/min for 5 min. The analyte of interest was monitored by tandem-mass spectrometry with electrospray positive ionization with a cone voltage 15 V for BPU and 30 V for the internal standard, paclitaxel. The detector settings allowed the monitoring of the [MH](+) ion of BPU (m/z 470.3) and the [MH](+) of internal standard paclitaxel (m/z 854.5), with subsequent monitoring of the product ions of BPU (m/z 148.0) and paclitaxel (m/z 286.1). Calibration curves were generated over the range of 0.05-10 ng/ml with values for coefficient of determination of >0.99. The values for precision and accuracy were BPU 5 mg as a weekly oral dose to a patient with advanced solid tumor malignancies, the maximum plasma concentration was 6.5 ng/ml and concentrations were quantifiable up to 173 h after administration. The lower limit of quantitation (LLOQ) of 0.05 ng/ml allows for successful measurement of plasma concentrations in patients receiving therapy with BPU as a once weekly oral dose.

  8. Rapid and sensitive determination of strychnine and brucine in human urine by capillary electrophoresis with field-amplified sample stacking.

    Science.gov (United States)

    Li, Junmei; Jiang, Ye

    2010-02-01

    A simple, rapid, sensitive and low-cost method using capillary electrophoresis (CE) coupled with field-amplified sample stacking (FASS) has been developed and validated for the simultaneous determination of strychnine and brucine residues in human urine. Before sample loading, a water plug (3.5 kPa, 3 s) was injected to contain sample cations and to permit FASS. Electrokinetic injection at a voltage (20 kV, 25 s) was then used to introduce cations. Separation was performed using 20 mM acetate buffer (pH 3.8) with an applied voltage of 20 kV. The calibration curves were linear over a range of 8.00-2.56 infinity 10(2) ng/mL (r = 0.9995) for strychnine and 10.0-3.20 x 10(2) ng/mL (r = 0.9999) for brucine. Extraction recoveries in urine were greater than 79.6 and 82.8% for strychnine and brucine, respectively, with an RSD of less than 4.9%. The detection limits (signal-to-noise ratio 3) for strychnine and brucine were 2.00 and 2.50 ng/mL, respectively. A urine sample from one healthy female volunteer (26 years old, 50 kg) was pretreated and analyzed. Strychnine and brucine levels in urine could be detected 24 h after administration. On these grounds, this method was feasible for application to preliminary screening of trace levels of abused drugs for both doping control and forensic analysis. (c) 2009 John Wiley & Sons, Ltd.

  9. Sensitive method for the determination of roxarsone using solid-phase microextraction with multi-detector gas chromatography.

    Science.gov (United States)

    Roerdink, Aaron R; Aldstadt, Joseph H

    2004-11-19

    We describe the development, optimization, and application of a novel method for the unequivocal identification and quantification of roxarsone (3-nitro-4-hydroxyphenylarsonic acid, 3-NHPAA) at low microg L(-1) levels. The method is based on capillary gas-liquid chromatography with parallel quadrupole ion-trap mass spectrometric (QIT-MS) and pulsed flame photometric detection (PFPD). The sensitive method couples the arsenic specificity of PFPD with the high selectivity of molecular MS for the determination of roxarsone, dimethylarsenic acid (DMAA), and monomethylarsonic acid (MMAA) in complex matrices. Analytes were derivatized based on the approach we previously reported [B. Szostek, J.H. Aldstadt, J. Chromatogr. A 807 (1998) 253 and D.R. Killelea, J.H. Aldstadt, J. Chromatogr. A 918 (2001) 169] for the reaction of organoarsenicals with 1,3-propanedithiol (PDT). The cyclic dithiaarsenolines formed were extracted from the sample matrix in the liquid phase by solid-phase microextraction (SPME). The optimized SPME conditions employed a 65 microm polydimethlysiloxane-divinylbenzene (PDMS-DVB) fiber, extraction temperature of 70 degrees C and fiber equilibration time of 15.0 min. The mass spectrum of the dithiaarsenoline of roxarsone showed a base peak that corresponded to the predicted structure at m/z 319 and the tell-tale peak of an arsenic compound derivatized with PDT at m/z 181. Further peaks at m/z 149 and 228 were observed and found to be unique to roxarsone, formed by an interesting internal rearrangement of the ONOH functionality. A linear calibration model was prepared for roxarsone over an environmentally relevant range (0.0-100 microg L(-1)) and a detection limit of 2.69 microg L(-1) (3sigma) was observed. The method was applied to several fortified environmental surface water samples (50 microg L(-1)) where the average recovery for roxarsone was 103+/-10.9%.

  10. A sensitive electrochemical impedance immunosensor for determination of malachite green and leucomalachite green in the aqueous environment.

    Science.gov (United States)

    Zhu, Dan; Li, Qiangqiang; Pang, Xiumei; Liu, Yue; Wang, Xue; Chen, Gang

    2016-08-01

    Application of malachite green (MG) and leucomalachite green (LMG) in fish farm water causes an environmental problem. This study proposes for the first time a sensitive and convenient electrochemical impedance spectroscopy (EIS) method for determining MG and LMG by a bovine serum albumin-decorated gold nanocluster (BSA-AuNC)/antibody composite film-based immunosensor. In order to improve the analytical performance, the glassy carbon electrode (GCE) was modified with 1, 4-phenylenediamine to form a stable layer, and then, BSA-AuNCs were covalently bound to the GCE. An adequate quantity of the polyclonal antibody of LMG was immobilized onto the surface of the BSA-AuNCs by the chemical reaction of EDC/NHS. The sensors can respond to the specific target based on specific covalent bonding. The experimental parameters, such as the pH, incubating concentration, and time, have been investigated and optimized. The calibration curve for LMG was linear in the range of 0.1~10.0 ng/mL with the limit of detection (LOD) 0.03 ng/mL. Furthermore, the sum of MG and LMG was detected in fish farm water by MG reduction. The recovery was between 89.7 % and 99.2 % in spiked samples. The EC sensor method was also compared with the ELISA method and validated by the LC-MS/MS method, which proves its great promise as a field instrument for the rapid monitoring of MG and LMG pollution. Graphical abstract 1, 4-Phenylenediamine and BSA-AuNC/antibody-decorated glassy carbon electrodes have been used for the impedimetric detection of the sum of malachite green and leucomalachite green via specific immuno-binding.

  11. 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.

  12. An analytical inversion method for determining regional and global emissions of greenhouse gases: Sensitivity studies and application to halocarbons

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2009-03-01

    Full Text Available A new analytical inversion method has been developed to determine the regional and global emissions of long-lived atmospheric trace gases. It exploits in situ measurement data from three global networks and builds on backward simulations with a Lagrangian particle dispersion model. The emission information is extracted from the observed concentration increases over a baseline that is itself objectively determined by the inversion algorithm. The method was applied to two hydrofluorocarbons (HFC-134a, HFC-152a and a hydrochlorofluorocarbon (HCFC-22 for the period January 2005 until March 2007. Detailed sensitivity studies with synthetic as well as with real measurement data were done to quantify the influence on the results of the a priori emissions and their uncertainties as well as of the observation and model errors. It was found that the global a posteriori emissions of HFC-134a, HFC-152a and HCFC-22 all increased from 2005 to 2006. Large increases (21%, 16%, 18%, respectively from 2005 to 2006 were found for China, whereas the emission changes in North America (−9%, 23%, 17%, respectively and Europe (11%, 11%, −4%, respectively were mostly smaller and less systematic. For Europe, the a posteriori emissions of HFC-134a and HFC-152a were slightly higher than the a priori emissions reported to the United Nations Framework Convention on Climate Change (UNFCCC. For HCFC-22, the a posteriori emissions for Europe were substantially (by almost a factor 2 higher than the a priori emissions used, which were based on HCFC consumption data reported to the United Nations Environment Programme (UNEP. Combined with the reported strongly decreasing HCFC consumption in Europe, this suggests a substantial time lag between the reported time of the HCFC-22 consumption and the actual time of the HCFC-22 emission. Conversely, in China where HCFC consumption is increasing rapidly according to the UNEP data, the a posteriori emissions are only about 40% of the a

  13. 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

  14. Hyperthermic potentiation of cisplatin by magnetic nanoparticle heaters is correlated with an increase in cell membrane fluidity

    Directory of Open Access Journals (Sweden)

    Alvarez-Berrios MP

    2013-03-01

    Full Text Available Merlis P Alvarez-Berríos, Amalchi Castillo, Janet Mendéz, Orlando Soto, Carlos Rinaldi, Madeline Torres-LugoDepartment of Chemical Engineering, University of Puerto Rico, Mayagüez, Puerto RicoAbstract: Magnetic fluid hyperthermia as a cancer treatment method is an attractive alternative to other forms of hyperthermia. It is based on the heat released by magnetic nanoparticles subjected to an alternating magnetic field. Recent studies have shown that magnetic fluid hyperthermia-treated cells respond significantly better to chemotherapeutic treatment compared with cells treated with hot water hyperthermia under the same temperature conditions. We hypothesized that this synergistic effect is due to an additional stress on the cellular membrane, independent of the thermal heat dose effect that is induced by nanoparticles exposed to an alternating magnetic field. This would result in an increase in Cis-diammine-dichloroplatinum (II (cDDP, cisplatin uptake via passive transport. To test this hypothesis, we exposed cDDP-treated cells to extracellular copper in order to hinder the human cell copper transporter (hCTR1-mediated active transport of cDDP. This, in turn, can increase the passive transport of the drug through the cell membrane. Our results did not show statistically significant differences in surviving fractions for cells treated concomitantly with magnetic fluid hyperthermia and cDDP, in the presence or absence of copper. Nonetheless, significant copper-dependent variations in cell survival were observed for samples treated with combined cDDP and hot water hyperthermia. These results correlated with platinum uptake studies, which showed that cells treated with magnetic fluid hyperthermia had higher platinum uptake than cells treated with hot water hyperthermia. Changes in membrane fluidity were tested through fluorescence anisotropy measurements using trimethylamine-diphenylhexatriene. Additional uptake studies were conducted with

  15. On-line Sweeping Sample Concentration in Micellar Electrokinetic Chromatography with Enhanced Sensitivity for the Determination of Carbamazepine in Human Serum

    Institute of Scientific and Technical Information of China (English)

    Dan Dan HAN; Chun WANG; Zhi WANG; Qiu Hua WU; Xiao Huan ZANG

    2006-01-01

    A sensitive and simple micellar electrokinetic chromatography (MEKC) method was developed for the determination of antiepileptic drug, carbamazepine (CBZ), using sweeping on-line concentration method with photodiode array detection. Under the optimal conditions, the method has been successfully applied to the analysis of CBZ in human serum.

  16. A simple and sensitive fully validated HPLC-UV method for the determination of 5-fluorouracil and its metabolite 5.6-dihydrofluorouracil in plasma

    NARCIS (Netherlands)

    Maring, JG; Greijdanus, B; de Vries, EGE; Uges, DRA

    2005-01-01

    The authors developed a simple and sensitive, fully validated HPLC-UV method for the determination of both 5-FU and its metabolite DHFU in small-volume plasma samples. The analytes were separated on a 4.6 X 250 mm ID Atlantis dC18 5-mum column with isocratic elution at room temperature. Chlorouracil

  17. 稳定剂对COM燃料流动性的影响%EFFECTS OF STABILIZING AGENT ON FLUIDITY IN COAL-OIL MIXTURE

    Institute of Scientific and Technical Information of China (English)

    刘德荣; 毛逢银; 张利

    2000-01-01

    Synthesis of stabilizing agents-methanol-epoxy propane(PO)-ethylene oxide(EO), glycerine-PO-EO, diglycerol-PO-EO,sorbierite-PO-EO,hexahydroxymethylmelamine-PO-EO additives was described and effects of number and molecular weight of branched chains, molar ratio of PO and EO, crosslink density of stabilizing agents on fluidity in coal-oil mixture (COM) were discussed in this article. When PO:EO is equal to 2, molecular weight above 5000, the stabilizing agent having suitable crosslink density with more branched chains gives better fluidity in COM. For hexahydroxymethyl melamine-PO-EO additive, when condensation of hexahydroxymethyl melamine in performed at pH=4.5 for 10min, copolymerization with PO and EO, and cross linking of copolymer by TDI to get polymer with MW 2 times higher than the copolymer, the maximum coal loading of 66% in COM can be reached.

  18. Paclitaxel/Taxol sensitivity in human renal cell carcinoma is not determined by the p53 status.

    Science.gov (United States)

    Reinecke, Petra; Kalinski, Thomas; Mahotka, Csaba; Schmitz, Michael; Déjosez, Marion; Gabbert, Helmut Erich; Gerharz, Claus Dieter

    2005-05-26

    In this study, we analyzed the role of the p53 status for paclitaxel/Taxol sensitivity in renal cell carcinomas (RCCs) of the clear cell type. Using immunohistochemistry, nuclear p53 accumulation could not be correlated to the paclitaxel/Taxol sensitivity. DNA sequencing detected a p53 gene mutation in two out of eight RCC cell lines, i.e. in exon 8 (cell line clearCa-6), and in exon 9 (cell line clearCa-5). No correlation, however, was found between the p53 status of our RCC cell lines and their paclitaxel/Taxol sensitivity as indicated by the IC50 values. However, paclitaxel-induced growth inhibition in paclitaxel-sensitive RCC cell lines was accompanied by an increase in apoptosis, irrespective of their p53 status. Although CD95 up-regulation was observed in renal cell carcinoma with wild-type p53 upon paclitaxel treatment, paclitaxel-induced apoptosis itself is triggered independently from the CD95 system. In conclusion, the p53 status cannot predict paclitaxel/Taxol sensitivity in RCC cell lines of the clear cell type.

  19. 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

  20. Unsaturated Fatty Acids Drive Disintegrin and Metalloproteinase (ADAM)-dependent Cell Adhesion, Proliferation, and Migration by Modulating Membrane Fluidity*

    Science.gov (United States)

    Reiss, Karina; Cornelsen, Isabell; Husmann, Matthias; Gimpl, Gerald; Bhakdi, Sucharit

    2011-01-01

    The disintegrin-metalloproteinases ADAM10 and ADAM17 mediate the release of several cell signaling molecules and cell adhesion molecules such as vascular endothelial cadherin or L-selectin affecting endothelial permeability and leukocyte transmigration. Dysregulation of ADAM activity may contribute to the pathogenesis of vascular diseases, but the mechanisms underlying the control of ADAM functions are still incompletely understood. Atherosclerosis is characterized by lipid plaque formation and local accumulation of unsaturated free fatty acids (FFA). Here, we show that unsaturated FFA increase ADAM-mediated substrate cleavage. We demonstrate that these alterations are not due to genuine changes in enzyme activity, but correlate with changes in membrane fluidity as revealed by measurement of 1,6-diphenyl-1,3,5-hexatriene fluorescence anisotropy and fluorescence recovery after photobleaching analyses. ELISA and immunoblot experiments conducted with granulocytes, endothelial cells, and keratinocytes revealed rapid increase of ectodomain shedding of ADAM10 and ADAM17 substrates upon membrane fluidization. Large amounts of unsaturated FFA may be liberated from cholesteryl esters in LDL that is entrapped in atherosclerotic lesions. Incubation of cells with thus modified LDL resulted in rapid cleavage of ADAM substrates with corresponding functional consequences on cell proliferation, cell migration, and endothelial permeability, events of high significance in atherogenesis. We propose that FFA represent critical regulators of ADAM function that may assume relevance in many biological settings through their influence on mobility of enzyme and substrate in lipid bilayers. PMID:21642425

  1. Unsaturated fatty acids drive disintegrin and metalloproteinase (ADAM)-dependent cell adhesion, proliferation, and migration by modulating membrane fluidity.

    Science.gov (United States)

    Reiss, Karina; Cornelsen, Isabell; Husmann, Matthias; Gimpl, Gerald; Bhakdi, Sucharit

    2011-07-29

    The disintegrin-metalloproteinases ADAM10 and ADAM17 mediate the release of several cell signaling molecules and cell adhesion molecules such as vascular endothelial cadherin or L-selectin affecting endothelial permeability and leukocyte transmigration. Dysregulation of ADAM activity may contribute to the pathogenesis of vascular diseases, but the mechanisms underlying the control of ADAM functions are still incompletely understood. Atherosclerosis is characterized by lipid plaque formation and local accumulation of unsaturated free fatty acids (FFA). Here, we show that unsaturated FFA increase ADAM-mediated substrate cleavage. We demonstrate that these alterations are not due to genuine changes in enzyme activity, but correlate with changes in membrane fluidity as revealed by measurement of 1,6-diphenyl-1,3,5-hexatriene fluorescence anisotropy and fluorescence recovery after photobleaching analyses. ELISA and immunoblot experiments conducted with granulocytes, endothelial cells, and keratinocytes revealed rapid increase of ectodomain shedding of ADAM10 and ADAM17 substrates upon membrane fluidization. Large amounts of unsaturated FFA may be liberated from cholesteryl esters in LDL that is entrapped in atherosclerotic lesions. Incubation of cells with thus modified LDL resulted in rapid cleavage of ADAM substrates with corresponding functional consequences on cell proliferation, cell migration, and endothelial permeability, events of high significance in atherogenesis. We propose that FFA represent critical regulators of ADAM function that may assume relevance in many biological settings through their influence on mobility of enzyme and substrate in lipid bilayers.

  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. Extraction of lignite coal fly ash for polynuclear aromatic hydrocarbons: modified and unmodified supercritical fluid extraction, enhanced-fluidity solvents, and accelerated solvent extraction.

    Science.gov (United States)

    Kenny, D V; Olesik, S V

    1998-02-01

    A comparison among modified and unmodified supercritical fluid extraction (SFE), enhanced-fluidity liquid extraction, and accelerated solvent extraction (ASE) techniques was made for the extraction of polynuclear aromatic hydrocarbons (PAHs) from an aged, spiked lignite coal fly ash. All of the attempted extraction conditions allowed the extraction of the PAHs to some degree, but no single extraction technique proved to be superior for all of the PAHs used. Three groups of PAHs with similar extraction efficiencies were identified. The group with the lowest molecular weights was best recovered using a 90% CO2-10% methanol mixture at 70 degrees C and 238 atm. The group of medium-molecular-weight PAHs was recovered equally well using any of three extraction conditions: SFE (100% CO2, 90 degrees C, and 238 atm), enhanced-fluidity liquid mixture (60% CO2-40% methanol, 70 degrees C, and 238 atm), and a methanol ASE mixture. The group of high-molecular-weight PAHs seemed to be equally well recovered with all of the attempted extraction conditions, but the enhanced-fluidity conditions (60% CO2-40% methanol, 70 degrees C, and 238 atm) had extraction recoveries (> 85%) with the lowest standard deviations (approximately 5%).

  4. 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.

  5. 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.

  6. Variable Hepatic Insulin Clearance with Attendant Insulinemia is the Primary Determinant of Insulin Sensitivity in the Normal Dog

    Science.gov (United States)

    Ader, Marilyn; Stefanovski, Darko; Kim, Stella P.; Richey, Joyce M.; Ionut, Viorica; Catalano, Karyn J.; Hucking, Katrin; Ellmerer, Martin; Van Citters, Gregg; Hsu, Isabel R.; Chiu, Jenny D.; Woolcott, Orison O.; Harrison, Lisa N.; Zheng, Dan; Lottati, Maya; Kolka, Cathryn M.; Mooradian, Vahe; Dittmann, Justin; Yae, Sophia; Liu, Huiwen; Castro, Ana Valeria B.; Kabir, Morvarid; Bergman, Richard N.

    2013-01-01

    OBJECTIVE Insulin resistance is a powerful risk factor for Type 2 diabetes and a constellation of chronic diseases, and is most commonly associated with obesity. We examined if factors other than obesity are more substantial predictors of insulin sensitivity under baseline, non-stimulated conditions. DESIGN AND METHODS Metabolic assessment was performed in healthy dogs (n=90). Whole-body sensitivity from euglycemic clamps (SICLAMP) was the primary outcome variable, and was measured independently by IVGTT (n=36). Adiposity was measured by MRI (n=90), and glucose-stimulated insulin response was measured from hyperglycemic clamp or IVGTT (n=86 and 36, respectively). RESULTS SICLAMP was highly variable (5.9 to 75.9 dl/min per kg per μU/ml). Despite narrow range of body weight (mean, 28.7±0.3 kg), adiposity varied ∼8-fold and was inversely correlated with SICLAMP (pinsulin, but most strongly associated with insulin clearance. Clearance was the dominant factor associated with sensitivity (r=0.53, pinsulin clearance contributes substantially to insulin sensitivity, and may be pivotal in understanding the pathogenesis of insulin resistance. We propose that hyperinsulinemia due to reduction in insulin clearance is responsible for insulin resistance secondary to changes in body weight. PMID:24123967

  7. A New Sensitive Sensor for Simultaneous Differential Pulse Voltammetric Determination of Codeine and Acetaminophen Using a Hydroquinone Derivative and Multiwall Carbon Nanotubes Carbon Paste Electrode

    Directory of Open Access Journals (Sweden)

    Elahe Garazhian

    2015-01-01

    Full Text Available A new sensitive sensor was fabricated for simultaneous determination of codeine and acetaminophen based on 4-hydroxy-2-(triphenylphosphoniophenolate (HTP and multiwall carbon nanotubes paste electrode at trace levels. The sensitivity of codeine determination was deeply affected by spiking multiwall carbon nanotubes and a modifier in carbon paste. Electron transfer coefficient, α, catalytic electron rate constant, k, and the exchange current density, j0, for oxidation of codeine at the HTP-MWCNT-CPE were calculated using cyclic voltammetry. The calibration curve was linear over the range 0.2–844.7 μM with two linear segments, and the detection limit of 0.063 μM of codeine was obtained using differential pulse voltammetry. The modified electrode was separated codeine and acetaminophen signals by differential pulse voltammetry. The modified electrode was applied for the determination of codeine and acetaminophen in biological and pharmaceutical samples with satisfactory results.

  8. Exploring the contextual sensitivity of factors that determine cell-to-cell variability in receptor-mediated apoptosis.

    Directory of Open Access Journals (Sweden)

    Suzanne Gaudet

    Full Text Available Stochastic fluctuations in gene expression give rise to cell-to-cell variability in protein levels which can potentially cause variability in cellular phenotype. For TRAIL (TNF-related apoptosis-inducing ligand variability manifests itself as dramatic differences in the time between ligand exposure and the sudden activation of the effector caspases that kill cells. However, the contribution of individual proteins to phenotypic variability has not been explored in detail. In this paper we use feature-based sensitivity analysis as a means to estimate the impact of variation in key apoptosis regulators on variability in the dynamics of cell death. We use Monte Carlo sampling from measured protein concentration distributions in combination with a previously validated ordinary differential equation model of apoptosis to simulate the dynamics of receptor-mediated apoptosis. We find that variation in the concentrations of some proteins matters much more than variation in others and that precisely which proteins matter depends both on the concentrations of other proteins and on whether correlations in protein levels are taken into account. A prediction from simulation that we confirm experimentally is that variability in fate is sensitive to even small increases in the levels of Bcl-2. We also show that sensitivity to Bcl-2 levels is itself sensitive to the levels of interacting proteins. The contextual dependency is implicit in the mathematical formulation of sensitivity, but our data show that it is also important for biologically relevant parameter values. Our work provides a conceptual and practical means to study and understand the impact of cell-to-cell variability in protein expression levels on cell fate using deterministic models and sampling from parameter distributions.

  9. A proposed experimental method to determine $\\alpha$-sensitivity of splitting between ground and 7.6 eV isomeric states in Th-229

    OpenAIRE

    Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V.; Porsev, S. G.

    2009-01-01

    The 7.6 eV electromagnetic transition between the nearly degenerate ground state and first excited state in the Th-229 nucleus may be very sensitive to potential changes in the fine-structure constant, $\\alpha = e^2/\\hbar c$. However, the sensitivity is not known, and nuclear calculations are currently unable to determine it. We propose measurements of the differences of atomic transition frequencies between thorium atoms (or ions) with the nucleus in the ground state and in the first excited...

  10. Perfect Fluidity of the Quark Gluon Plasma Core as Seen through its Dissipative Hadronic Corona

    CERN Document Server

    Hirano, T; Hirano, Tetsufumi; Gyulassy, Miklos

    2006-01-01

    The agreement of hydrodynamic predictions of differential elliptic flow and radial flow patterns with Au+Au data is one of the main lines of evidence suggesting the nearly perfect fluid properties of the strongly coupled Quark Gluon Plasma, sQGP, produced at RHIC. We study the sensitivity of this conclusion to different hydrodynamic assumptions on chemical and thermal freezeout after the sQGP hadronizes. We show that if chemical freezeout occurs at the hadronization time, the differential elliptic flow for pions increase with proper time in the late hadronic phase until thermal freezeout and leads to a discrepancy with the data. In contrast, if both chemical and thermal equilibrium are maintained past the hadronization, then the mean pT per pion increases in a way that accidentally preserves v2(pT) from the sQGP phase in agreement with the data, but at the cost of the agreement with the hadronic yields. In order that all the data on hadronic ratios, radial flow, and differential elliptic flow be reproduced, t...

  11. Application of a sensitive and specific reagent for the determination of serum iron to the Bayer DAX48.

    Science.gov (United States)

    Artiss, J D; Yang, W C; Harake, B; Capellari, E; Kretch, C; Eisenbrey, A B; Zak, B

    1997-09-01

    We describe a modification of a previously described serum iron procedure applied to the Bayer DAX48 (Bayer Diagnostics, Tarrytown, NY) automated chemistry analyzer. The iron-ligand used in this assay, 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamine) phenol (nitro-PAPS), has a molar absorptivity of 94,000 L mol(-1) cm(-1), which is three to four times more sensitive than the more commonly used ligands. The increased sensitivity of the iron-ligand complex facilitates modification of a Ferene S method that requires a smaller sample volume while it maintains the precision of the assay. Because the reagent does not contain ascorbate, the "onboard" stability has been increased to more than 4 weeks. The reagent seems to be quite insensitive to icterus and hemolysis. Furthermore, the interference of turbidity caused by triglycerides, abnormal proteins, or fibrinogen, present in samples from patients undergoing anticoagulant therapy, seems to have been eliminated.

  12. A novel technique for response function determination of shear sensitive cholesteric liquid crystals for boundary layer investigations

    Science.gov (United States)

    Parmar, D. S.

    1991-01-01

    A description of the design and setup of an experimental technique for measurement of the response function in shear sensitive liquid crystals has been reported. Utilizing the selective reflection characteristics of cholesteric liquid crystals, the method is capable of measuring the delay, rise, and relaxation times in response to a given dynamic shear stress as a function of the wavelength of the incident light. Application of a step input shear stress results in a liquid crystal time response that can be described as consisting of an initial delay, a shear induced helix deformation, and a relaxation to the initial state through diffusion processes. The method has been used for quantitative calibration of a shear sensitive liquid crystal by observing the peak in reflected light intensity, at a given wavelength, as a function of the shear stress.

  13. 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

  14. Liquid-phase exfoliated graphene as highly-sensitive sensor for simultaneous determination of endocrine disruptors: diethylstilbestrol and estradiol.

    Science.gov (United States)

    Hu, Lintong; Cheng, Qin; Chen, Danchao; Ma, Ming; Wu, Kangbing

    2015-01-01

    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 0.28V and 0.49V 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.

  15. Sensitivity analysis and determination of free relaxation parameters for the weakly-compressible MRT-LBM schemes

    CERN Document Server

    Xu, Hui; Sagaut, Pierre

    2011-01-01

    It is well-known that there exist several free relaxation parameters in the MRT-LBM. Although these parameters have been tuned via linear analysis, the sensitivity analysis of these parameters and other related parameters are still not sufficient for detecting the behaviors of the dispersion and dissipation relations of the MRT-LBM. Previous researches have shown that the bulk dissipation in the MRT-LBM induces a significant over-damping of acoustic disturbances. This indicates that MRT-LBM cannot be used to obtain the correct behavior of pressure fluctuations because of the fixed bulk relaxation parameter. In order to cure this problem, an effective algorithm has been proposed for recovering the linearized Navier-Stokes equations from the linearized MRT-LBM. The recovered L-NSE appear as in matrix form with arbitrary order of the truncation errors with respect to ${\\delta}t$. Then, in wave-number space, the first/second-order sensitivity analyses of matrix eigenvalues are used to address the sensitivity of t...

  16. 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.

  17. High-sensitivity microchip electrophoresis determination of inorganic anions and oxalate in atmospheric aerosols with adjustable selectivity and conductivity detection.

    Science.gov (United States)

    Noblitt, Scott D; Schwandner, Florian M; Hering, Susanne V; Collett, Jeffrey L; Henry, Charles S

    2009-02-27

    A sensitive and selective separation of common anionic constituents of atmospheric aerosols, sulfate, nitrate, chloride, and oxalate, is presented using microchip electrophoresis. The optimized separation is achieved in under 1 min and at low background electrolyte ionic strength (2.9 mM) by combining a metal-binding electrolyte anion (17 mM picolinic acid), a sulfate-binding electrolyte cation (19 mM HEPBS), a zwitterionic surfactant with affinity towards weakly solvated anions (19 mM N-tetradecyl,N,N-dimethyl-3-ammonio-1-propansulfonate), and operation in counter-electroosmotic flow (EOF) mode. The separation is performed at pH 4.7, permitting pH manipulation of oxalate's mobility. The majority of low-concentration organic acids are not observed at these conditions, allowing for rapid subsequent injections without the presence of interfering peaks. Because the mobilities of sulfate, nitrate, and oxalate are independently controlled, other minor constituents of aerosols can be analyzed, including nitrite, fluoride, and formate if desired using similar separation conditions. Contact conductivity detection is utilized, and the limit of detection for oxalate (S/N=3) is 180 nM without stacking. Sensitivity can be increased with field-amplified sample stacking by injecting from dilute electrolyte with a detection limit of 19 nM achieved. The high-sensitivity, counter-EOF operation, and short analysis time make this separation well-suited to continuous online monitoring of aerosol composition.

  18. Investigation of stress-induced birefringence of tissue determined with polarisation sensitive optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Karnowski, Karol; Li, Qingyun; Villiger, Martin; Sampson, David D.

    2017-02-01

    Polarisation sensitive optical coherence tomography (PS-OCT) offers additional intrinsic contrast to probe differences between healthy tissue and cancer that are often barely visible due to limited scattering contrast in an OCT image. PS-OCT reconstructs tissue birefringence from phase-sensitive measurements of orthogonal polarisation components of backscattering. In material science, polarisation has been used to study stress distribution, including the birefringence induced by stress in an otherwise isotropic material. Similar effects in biological tissues have not been well studied yet; however, may have application to tissues subjected to stress, e.g., tendons, muscles, lens, cornea or airway smooth muscle (ASM). The objective of this work is to explore stress-induced birefringence in tissue. We employ an advanced swept source-based PS-OCT system capable of measurement of tissue local polarisation properties. The sample in both cases is illuminated with orthogonal, passively depth-encoded polarisation states. Light returning from the tissue is detected via a polarisation-diversity detection module and a Mueller formalism is used to reconstruct polarisation properties (including retardation, diattenuation, and depolarisation) of the tissue. In this study, we demonstrate the measurement of stress-induced birefringence in phantoms and in soft tissues with polarisation sensitive optical coherence tomography.

  19. Simultaneous determination of soy isoflavone glycosides, daidzin and genistin by monoclonal antibody-based highly sensitive indirect competitive enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Sakamoto, Seiichi; Yusakul, Gorawit; Pongkitwitoon, Benyakan; Paudel, Madan Kumar; Tanaka, Hiroyuki; Morimoto, Satoshi

    2015-02-15

    Soy isoflavones are known as major bioactive compounds in soybean (Glycine max), which is an indispensable food. Despite their utility, the consumption of isoflavones has recently been limited because they exhibit oestrogenic and topoisomerase II inhibitory effects. To assess their intake limitation, accurate, sensitive, and effective quantitative analyses are necessary. In this study, we produced the monoclonal antibody (MAb) against daidzin (DZ) and applied it to an indirect competitive enzyme-linked immunosorbent assay (icELISA) for the simultaneous determination of DZ and genistin (GEN), which are known as two major soy isoflavone glycosides in soy products. Using the DZ-MAb, we developed a sensitive icELISA method, where the limit of detection for DZ and GEN was 1.95ng/ml. Several validation analyses revealed that the icELISA is sufficiently accurate and sensitive to be used to assess the overconsumption of soy isoflavones, which would lead to the safe dietary intake of soy products.

  20. An ultra-sensitive LC-MS/MS method to determine midazolam levels in human plasma: development, validation and application to a clinical study.

    Science.gov (United States)

    Chen, Mu; Lu, Wenzhe; Lu, Yang; Kang, Lijuan; Zhao, Harry; Lin, Zhongping John; Wang, Weimin; Fraier, Daniela; Ottaviani, Giorgio

    2017-02-01

    Midazolam is a commonly used marker substrate for the in vivo assessment of CYP3A activity. Reliable pharmacokinetic assessment at sub-pharmacological doses of midazolam requires an ultra-sensitive analytical method. A new, ultra-sensitive LC-MS/MS method for the determination of midazolam in human plasma using SPE was developed and fully validated. The lowest limit of quantitation is 0.1 pg/ml with a sample volume of 500 μl. The following parameters were validated: sensitivity, assay accuracy and precision, linearity, selectivity, and stability of midazolam at pertinent analytical and storage conditions. The validated method was utilized successfully for the sample assay during a midazolam microdosing study for the evaluation of CYP3A4 activity of a clinical candidate.

  1. Effects of Chuanxiongqin hydrochloride on increasing the fluidity of brain cell membrane and scavenging free radicals in model rats with ischemia/reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Chenxu Li

    2006-01-01

    BACKGROUND: The fluidity of cell membrane can be affected by various factors. Many experiments have confirmed that the ischemia/reperfusion of organic tissue can increase the contents of free radicals, which lead to high rigidity and Iow fluidity of cell membrane, and the conditions can be changed by Chuanxiongqin.OBJECTIVE: To observe the effect and mechanism of Chuanxiongqin hydrochloride on the fluidity of brain cell membrane in rat models of ischemia/reperfusion.DESIGN: A completely randomized controlled animal trial.SETTINGS: Institute of Brain Sciences; Department of Physiology, Medical College, Datong University.MATERIALS: Twenty male grade I Wistar rats of 170-220 g were randomly divided into model group (n =10)and control group (n =10). Chuanxiongqin hydrochloride (molecular mass was 172.2) was purchased from the National Institute for the Control of Pharmaceutical and Biological Products (batch number; 0817-9803); Spin labelers: 5-cfoxyl-stearlic acid methylester (5DS), 16-doxyl-stearlic acid methylester (16DS), xanthine, xanthine oxidase (XOD) and 5,5-dimeth-1-pyrroline- N-oxide (DMPO) from Sigma Company; Bruker ESP 300 electron paramagnetic resonance (EPR) spectrometer by Bruker Company (Germany).METHODS: The experiments were carried out in the State Key Laboratory of Natural and Biomimetic Drugs,Peking University from June 2001 to July 2002. In the model group, rats were made into models of cerebral ischemia by 30-minute ligation and 2-hour reperfusion of common carotid arteries; The rats in the control group were not made into models. The order parameter (S) and rotational correlation time (тc) were detected with the ESR spectrometer by means of spin labeling. The greater the S and тc, the smaller the fluidity. Meanwhile, the clearance rate of free radicals was detected with ESR spin trapping. The measurement data were compared using the ttest.MAIN OUTCOME MEASURES: The S, тc and clearance rates of O2 and OH free radicals were compared between the

  2. Alterations in the Noxa/Mcl-1 axis determine sensitivity of small cell lung cancer to the BH3 mimetic ABT-737.

    Science.gov (United States)

    Hauck, Paula; Chao, Bo H; Litz, Julie; Krystal, Geoffrey W

    2009-04-01

    To understand the molecular basis for variable sensitivity to the BH3 mimetic drug ABT-737, the abundance of Bcl-2 family members was assayed in a panel of small cell lung cancer cell lines whose sensitivity varied over a 2-log range. Elevated Noxa and Bcl-2 levels directly correlated with sensitivity to ABT-737, whereas Mcl-1 levels were similar in all cell lines tested regardless of sensitivity. Transgenically enforced expression of Noxa but not Bcl-2 resulted in increased sensitivity to ABT-737 in multiple cell lines. This increase was especially pronounced in the H209 cell line in which expression of Noxa resulted in a proportionate decline in Mcl-1 expression. Although overexpression of Noxa enhanced sensitivity of the H526 and H82 cell lines to ABT-737, it did not result in altered Mcl-1 levels. Similarly, small interfering RNA-mediated knockdown of Noxa expression in the H146 cell line, which increased resistance to ABT-737, did not result in altered Mcl-1 levels. Therefore, three of four cell lines studied failed to show Noxa-mediated regulation of Mcl-1 expression. However, despite failure to regulate Mcl-1 levels, Noxa blocked binding of Bim to Mcl-1 following its release from Bcl-2 by ABT-737. Finally, we observed that a 24-hour incubation of the H526 and WBA cell lines with ABT-737 resulted in increased Noxa expression, suggesting that Noxa may play a direct role in ABT-737-mediated apoptosis. These results indicate that Noxa expression is the critical determinant of ABT-737 sensitivity and loss of Noxa-mediated regulation of Mcl-1 expression may be an important feature of small cell lung cancer biology.

  3. Continuous flow atomic force microscopy imaging reveals fluidity and time-dependent interactions of antimicrobial dendrimer with model lipid membranes.

    Science.gov (United States)

    Lind, Tania Kjellerup; Zielińska, Paulina; Wacklin, Hanna Pauliina; Urbańczyk-Lipkowska, Zofia; Cárdenas, Marité

    2014-01-28

    In this paper, an amphiphilic peptide dendrimer with potential applications against multi-resistant bacteria such as Staphylococcus aureus was synthesized and studied on model cell membranes. The combination of quartz crystal microbalance and atomic force microscopy imaging during continuous flow allowed for in situ monitoring of the very initial interaction processes and membrane transformations on longer time scales. We used three different membrane compositions of low and high melting temperature phospholipids to vary the membrane properties from a single fluid phase to a pure gel phase, while crossing the phase coexistence boundaries at room temperature. The interaction mechanism of the dendrimer was found to be time-dependent and to vary remarkably with the fluidity and coexistence of liquid-solid phases in the membrane. Spherical micelle-like dendrimer-lipid aggregates were formed in the fluid-phase bilayer and led to partial solubilization of the membrane, while in gel-phase membranes, the dendrimers caused areas of local depressions followed by redeposition of flexible lipid patches. Domain coexistence led to a sequence of events initiated by the formation of a ribbon-like network and followed by membrane solubilization via spherical aggregates from the edges of bilayer patches. Our results show that the dendrimer molecules were able to destroy the membrane integrity through different mechanisms depending on the lipid phase and morphology and shed light on their antimicrobial activity. These findings could have an impact on the efficacy of the dendrimers since lipid membranes in certain bacteria have transition temperatures very close to the host body temperature.

  4. Influence of lysophospholipid hydrolysis by the catalytic domain of neuropathy target esterase on the fluidity of bilayer lipid membranes.

    Science.gov (United States)

    Greiner, Aaron J; Richardson, Rudy J; Worden, R Mark; Ofoli, Robert Y

    2010-08-01

    Neuropathy target esterase (NTE) is an integral membrane protein localized in the endoplasmic reticulum in neurons. Irreversible inhibition of NTE by certain organophosphorus compounds produces a paralysis known as organophosphorus compound-induced delayed neuropathy. In vitro, NTE has phospholipase/lysophospholipase activity that hydrolyses exogenously added single-chain lysophospholipids in preference to dual-chain phospholipids, and NTE mutations have been associated with motor neuron disease. NTE's physiological role is not well understood, although recent studies suggest that it may control the cytotoxic accumulation of lysophospholipids in membranes. We used the NTE catalytic domain (NEST) to hydrolyze palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (p-lysoPC) to palmitic acid in bilayer membranes comprising 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and the fluorophore 1-oleoyl-2-[12-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]dodecanoyl]-sn-glycero-3-phosphocholine (NBD-PC). Translational diffusion coefficients (D(L)) in supported bilayer membranes were measured by fluorescence recovery after pattern photobleaching (FRAPP). The average D(L) for DOPC/p-lysoPC membranes without NEST was 2.44 microm(2)s(-1)+/-0.09; the D(L) for DOPC/p-lysoPC membranes containing NEST and diisopropylphosphorofluoridate, an inhibitor, was nearly identical at 2.45+/-0.08. By contrast, the D(L) for membranes comprising NEST, DOPC, and p-lysoPC was 2.28+/-0.07, significantly different from the system with inhibited NEST, due to NEST hydrolysis. Likewise, a system without NEST containing the amount of palmitic acid that would have been produced by NEST hydrolysis of p-lysoPC was identical at 2.26+/-0.06. These results indicate that NTE's catalytic activity can alter membrane fluidity. Copyright 2010 Elsevier B.V. All rights reserved.

  5. Liquid chromatography-mass spectrometric method for the sensitive determination of niflumic acid in human plasma and its application to pharmacokinetic study of talniflumate tablet.

    Science.gov (United States)

    Park, Eun Ji; Na, Dong Hee; Shin, Young-Hee; Lee, Kang Choon

    2008-12-15

    A sensitive LC-MS method was developed and validated for the determination of niflumic acid (NFA), the active metabolite of the talniflumate formulation, in human plasma. The analyses were performed on C(18) column using acetonitrile-ammonium acetate buffer (pH 5.7, 40:60) as a mobile phase with quadrupole MS detection of NFA at m/z 281 in a negative ion-monitoring mode. Calibration curve was linear in the concentration range of 1-1000ng/mL in human plasma. The higher sensitivity of LC-MS allowed low concentrations of NFA to be determined at initial drug absorption and terminal elimination phases following oral administration of talniflumate tablet.

  6. Sensitive determination of Amaranth in drinks by highly dispersed CNT in graphene oxide "water" with the aid of small amounts of ionic liquid.

    Science.gov (United States)

    Wang, Meiling; Sun, Yinlu; Yang, Xiongbo; Zhao, Jianwei

    2015-07-15

    Graphene oxide (GO) is a pH-dependent amphiphile. In this paper, it was found that carbon nanotubes (CNTs) can be highly dispersed in graphene oxide "water" with the aid of prototype ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). The introduction of [BMIM][PF6] not only can minimize the defects of poor electrical conductivity of GO, but also can improve the dispersibility of CNT in water. Hence, a new composite of CNT/GO-[BMIM][PF6] with high dispersibility and strong conductivity was presented for the first time and employed in the sensitive determination of Amaranth in soft drinks. The detection limit achieved (0.1 nM) is much lower than the guideline values in soft drinks. The ease of preparation, low background current, high sensitivity and stability can create novel avenues and applications for fabricating robust sensors for determination of other azo dyes in foods.

  7. Sensitive determination of the spin polarization of optically pumped alkali-metal atoms using near-resonant light

    Science.gov (United States)

    Ding, Zhichao; Long, Xingwu; Yuan, Jie; Fan, Zhenfang; Luo, Hui

    2016-09-01

    A new method to measure the spin polarization of optically pumped alkali-metal atoms is demonstrated. Unlike the conventional method using far-detuned probe light, the near-resonant light with two specific frequencies was chosen. Because the Faraday rotation angle of this approach can be two orders of magnitude greater than that with the conventional method, this approach is more sensitive to the spin polarization. Based on the results of the experimental scheme, the spin polarization measurements are found to be in good agreement with the theoretical predictions, thereby demonstrating the feasibility of this approach.

  8. Long wavelength perfect fluidity from short distance jet transport in quark-gluon plasmas

    CERN Document Server

    Xu, Jiechen; Gyulassy, Miklos

    2015-01-01

    We build a new phenomenological framework that bridges the long wavelength bulk viscous transport properties of the strongly-coupled quark-gluon plasma (sQGP) and short distance hard jet transport properties in the QGP. The full nonperturbative chromo-electric (E) and chromo-magnetic (M) structure of the near "perfect fluid" like sQGP in the critical transition region are integrated into a semi-Quark-Gluon-Monopole Plasma (sQGMP) model lattice-compatibly and implemented into the new CUJET3.0 jet quenching framework. All observables computed from CUJET3.0 are found to be consistent with available data at RHIC and LHC simultaneously. A quantitative connection between the shear viscosity and jet transport parameter is rigorously established within this framework. We deduce the $T=160-600$ MeV dependence of the QGP's $\\eta/s$: its near vanishing value in the near $T_c$ regime is determined by the composition of E and M charges, it increases as $T$ rises, and its high $T$ limit is fixed by color screening scales.

  9. Long wavelength perfect fluidity from short distance jet transport in quark-gluon plasmas

    Science.gov (United States)

    Xu, Jiechen; Liao, Jinfeng; Gyulassy, Miklos

    2016-12-01

    We build a new phenomenological framework that bridges the long wavelength bulk viscous transport properties of the strongly-coupled quark-gluon plasma (sQGP) and short distance hard jet transport properties in the QGP. The full nonperturbative chromo-electric (E) and chromo-magnetic (M) structure of the near "perfect fluid" like sQGP in the critical transition region are integrated into a semi-Quark-Gluon-Monopole Plasma (sQGMP) model lattice-compatibly and implemented into the new CUJET3.0 jet quenching framework. All observables computed from CUJET3.0 are found to be consistent with available data at RHIC and LHC simultaneously. A quantitative connection between the shear viscosity and jet transport parameter is rigorously established within this framework. We deduce the T = 160 - 600 MeV dependence of the QGP's η / s: its near vanishing value in the near Tc regime is determined by the composition of E and M charges, it increases as T rises, and its high T limit is fixed by color screening scales.

  10. Sensitive determination of 4-O-methylhonokiol in rabbit plasma by high performance liquid chromatography and application

    Institute of Scientific and Technical Information of China (English)

    Ming-Yue Li; Yu-Hai Tang; Xia Liu; Hai-Yan Lu; Xi-Yan Shi

    2011-01-01

    A novel high performance liquid chromatographic method was developed for the determination of 4-O- methylhonokiol in rabbit plasma and was applied to its pharmacokinetic investigation. Plasma samples were treated by one-fold volume of methanol and acetoni

  11. Membrane fluidity and the surface properties of the lipid bilayer: ESR experiment and computer simulation.

    Science.gov (United States)

    Man, Dariusz; Olchawa, Ryszard; Kubica, Krystian

    2010-09-01

    Penetration of the liposome membranes formed in the gel phase from DPPC (DPPC liposomes) and in the liquid-crystalline phase from egg yolk lecithin (EYL liposomes) by the TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) and 16 DOXYL (2-ethyl-2-(15-methoxy-oxopentadecyl)-4,4-dimethyl-3-oxazolidinyloxy) spin probes has been investigated. The penetration process was followed by 120 hours at 24(0)C, using the electron spin resonance (ESR) method. The investigation of the kinetics of the TEMPO probe building into the membranes of both types of liposomes revealed differences appearing 30 minutes after the start of the experiment. The number of TEMPO particles built into the EYL liposome membranes began to clearly rise, aiming asymptotically to a constant value after about 100 minutes, whereas the number of the TEMPO particles built into the DPPC liposome membranes was almost constant in time. The interpretation of the obtained experimental results was enriched with those of computer simulation, following the behavior of the polar heads (dipoles) of the lipid particles forming a lipid layer due to the change in the value of the model parameter, k, determining the mobility of the dipoles. The possibility of the formation of an irregular ordering of the polar part of lipid membranes was proved, which leads to the appearance of spaces filled with of water for k > 0.4. The appearance of these defects enables the penetration of the bilayer by the TEMPO particles. The limited mobility of lipid polar heads (k < 0.2) prevents the appearance of such areas facilitating the penetration of the lipid membrane by alien particles in the gel phase.

  12. Electropolymerized poly(Toluidine Blue)-modified carbon felt for highly sensitive amperometric determination of NADH in flow injection analysis

    Institute of Scientific and Technical Information of China (English)

    Yasushi Hasebe; Yue Wang; Kazuya Fukuoka

    2011-01-01

    Poly(pheniothiazine) films were prepared on a porous carbon felt (CF) electrode surface by an electrooxidative polymerization of three phenothiazine derivatives (i.e.,Tthionine (TN), Toluidine Blue (TB) and Methylene Blue (MB)) from 0.1 mol/L phosphate buffer solution (pH 7.0).Among the three phenothiazies, the poly(TB) film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form (NADH) at +0.2 V vs.Ag/AgCl.The poly(TB) film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH.The peak currents (peak heights) were almost unchanged, irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min, resulting in the measurement of NADH (ca.30 samples/hr) at 4.1 mL/min.The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 μmol/L (sensitivity: 0.318 μA/(μmol/L); correlation coefficient: 0.997).The lower detection limit was found to be 0.3 μmol/L (S/N = 3).

  13. Oxytocin determination by radioimmunoassay. III. Improvement to subpicogram sensitivity and application to blood levels in cyclic cattle

    Energy Technology Data Exchange (ETDEWEB)

    Schams, D. (Insitut fuer Physiologie der Sueddeutschen Versuchs- und Forschungsanstalt der Technischen Universitaet Muenchen, FRG)

    1983-01-01

    An improved RIA for measurement of oxytocin in blood is described by using an extraction method with SEP-PAK C/sub 18/ cartridges, which allows also concentration of the sample, a new antiserum with a higher sensitivity to standard oxytocin and preparation of the standard curve in buffer. The lower limit of assay sensitivity was 0.25 pg/tube, corresponding to 0.25-1.0 pg/ml plasma depending on the amount of plasma extracted. Hence, it was no problem to measure oxytocin basal concentrations in peripheral blood in the range of 0.6-4 pg/ml plasma depending on the stage of the oestrous cycle. The highest oxytocin concentrations occurred during the early and mid-luteal phase. The method has been applied also for samples from women, sheep, pigs and horses. Mean (+-SD) recovery of oxytocin added to plasma or only buffer after extraction was 71.3+-8,1%, and the coefficient of variation (CV) = 11.4% (n = 27 assays). The intra-assay CV of two control samples was 7.9+-2.8 and 7.8+-2.4% (n = 17 assays). The inter-assay CV of 5 control samples with low and high oxytocin concentrations varied between 10.8+-17.3% (n = 25 assays). The 50% intercept was 2.5+-0.3 pg, CV = 11.3% (n = 29 assays).

  14. Ascorbic Acid Assisted Synthesis of Cobalt Oxide Nanostructures, Their Electrochemical Sensing Application for the Sensitive Determination of Hydrazine

    Science.gov (United States)

    Tahira, Aneela; Nafady, Ayman; Baloach, Quarratulain; Sirajuddin; Sherazi, Syed Tufail Hussain; Shaikh, Tayyaba; Arain, Munazza; Willander, Magnus; Ibupoto, Zafar Hussain

    2016-07-01

    This study describes, the synthesis of cobalt oxide nanostructures using ascorbic acid as a growth directing agent by the hydrothermal method. Ascorbic acid is used for the first time for the synthesis of cobalt oxide nanostructures and a unique morphology is prepared in the present study. The cobalt oxide nanostructures were characterized by scanning electron microcopy, x-ray diffraction, and x-ray photoelectron spectroscopy techniques. These analytical techniques demonstrated well defined morphology, good crystalline quality, and high purity of as prepared cobalt oxide nanostructures. The glassy carbon electrode was modified with cobalt oxide nanostructures for the development of a sensitive and selective electrochemical hydrazine sensor. The developed hydrazine sensor exhibits a linear range of 2-24 μM. The sensitivity and limit of detection of presented hydrazine sensors are 12,734 μA/mM/cm2 and 0.1 μM respectively. The developed hydrazine sensor is highly selective, stable, and reproducible. The proposed sensor is successfully applied for the detection of hydrazine from different water samples. The present study provides the development of an alternative tool for the reliable monitoring of hydrazine from environmental and biological samples.

  15. Simple and sensitive determination of papain by resonance light-scattering with CdSe quantum dots.

    Science.gov (United States)

    Huang, Shan; Xiao, Qi; Su, Wei; Li, Peiyuan; Ma, Jianqiang; He, Zhike

    2013-02-01

    In this contribution, a simple and sensitive method for papain detection was established based on the increment of the resonance light-scattering (RLS) intensity of mercaptoacetic acid-capped CdSe quantum dots (MAA-QDs) in aqueous solution. Meanwhile, the RLS characteristics and the optimal conditions were investigated in detail. Under the optimized conditions, the linear range of MAA-QDs RLS intensity versus the concentration of papain was 1.0×10(-8) M to 6.0×10(-7) M, with a correlation coefficient (R(2)) of 0.9977 and a limit of detection (3σ black) of 5.1×10(-9) M. The relative standard deviation (R.S.D.) for 1.6×10(-7) M papain was 1.0% (n=5). There was almost no interference to coexisting foreign substances including common ions, proteins and 20 amino acids. The proposed method possessed the advantages of simplicity, rapidity and sensitivity. Three synthetic samples were analyzed by the methodology and the results were satisfying. The interaction between MAA-QDs and papain was also investigated systematically by using visual method, transmission electron microscopy and time-resolved fluorescence spectra, and the results indicated that the main force between MAA-QDs and papain was electrostatic interaction.

  16. Nature of the charged headgroup determines the fusogenic potential and membrane properties of lithocholic acid phospholipids.

    Science.gov (United States)

    Bhargava, Priyanshu; Singh, Manish; Sreekanth, Vedagopuram; Bajaj, Avinash

    2014-08-07

    Phospholipids play a crucial role in many cellular processes ranging from selective membrane permeability, to membrane fission and fusion, to cellular signaling. Headgroups of phospholipids determine the membrane properties and fusogenicity of these lipids with target cell membranes. We studied the fusogenic and membrane properties of phospholipids possessing unnatural charged headgroups with model membranes using laurdan based membrane hydration studies, DPH based membrane fluidity, and differential scanning calorimetry. We unravel that fusogenicity, membrane hydration, and fluidity of membranes are strongly contingent on the nature of the phospholipid charged headgroup. Our studies unraveled that introduction of bulky headgroups like dimethylamino pyridine induces maximum membrane hydration and perturbations with high fusogenicity as compared to small headgroup based phospholipids. These phospholipids also have the capability of high retention in DPPC membranes. Hydration and fluidity of these phospholipid-doped DPPC membranes are contingent on the nature of the charged headgroup. This study would help in future design of phospholipid based nanomaterials for effective drug delivery.

  17. Determination of (3)J((1)H3'-(31)P) couplings in a DNA oligomer with enhanced sensitivity employing a constant-time TOCSY difference experiment.

    Science.gov (United States)

    Reith, Lorenz M; Schlagnitweit, Judith; Smrecki, Vilko; Knör, Günther; Müller, Norbert; Schoefberger, Wolfgang

    2011-03-01

    A constant-time TOCSY difference experiment for the determination of (3)J((1)H3'-(31)P) coupling constants in non-isotope-labelled DNA oligonucleotides is presented. The method is tested on a DNA octamer and compared with the established constant-time NOESY difference method. Each (3)J((1)H3'-(31)P) coupling constant is determined from amplitude changes caused by phosphorous decoupling, which are observable on multiple cross-peaks, thus leading to a high accuracy of the value of the (3)J((1)H3'-(31)P) coupling constant. The new experiment delivers up to three times the sensitivity compared with previously reported methods.

  18. Highly Sensitive Spectrofluorimetric Determination of Riboflavin Based on the Generation of Active Oxygen Coupled with Enzymatic Reaction

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A spectrofluorimetric method for the determining riboflavin (VB2) based on its enhancement on the fluorescence of hemoglobin-catalyzed enzymatic reaction was proposed. The proposed method consisted of two reactions. One was the photochemical reaction of VB2, the other was a hemoglobin-catalyzed enzymatic reaction. The optimal experimental conditions for the determinations were established. The linear range of the method was 5.0×10-9-1.0×10-7mol/L of VB2. The detection limit was calculated to be 3.65×10-9 mol/L. The relative standard deviation of this method was 2.3 % at 7.0×10-8 mol/L for 11 determinations.

  19. A rapid and sensitive assay for determination of doxycycline using thioglycolic acid-capped cadmium telluride quantum dots.

    Science.gov (United States)

    Tashkhourian, Javad; Absalan, Ghodratollah; Jafari, Marzieh; Zare, Saber

    2016-01-05

    A rapid, simple and inexpensive spectrofluorimetric sensor for determination of doxycycline based on its interaction with thioglycolic acid-capped cadmium telluride quantum dots (TGA/CdTe QDs) has been developed. Under the optimum experimental conditions, the sensor exhibited a fast response time of <10s. The results revealed that doxycycline could quench the fluorescence of TGA/CdTe QDs via electron transfer from the QDs to doxycycline through a dynamic quenching mechanism. The sensor permitted determination of doxycycline in a concentration range of 1.9×10(-6)-6.1×10(-5)molL(-1) with a detection limit of 1.1×10(-7)molL(-1). The sensor was applied for determination of doxycycline in honey and human serum samples.

  20. Determination of late-time Gamma-Ray (60Co) sensitivity of single diffusion Lot 2N2222A transistors.

    Energy Technology Data Exchange (ETDEWEB)

    DePriest, Kendall Russell; Kajder, Karen C.; Peters, Curtis D. (American Staff Augmentation Providers, LLC, Albuquerque, NM)

    2008-08-01

    Sandia National Laboratories (SNL) has embarked on a program to develop a methodology to use damage relations techniques (alternative experimental facilities, modeling, and simulation) to understand the time-dependent effects in transistors (and integrated circuits) caused by neutron irradiations in the Sandia Pulse Reactor-III (SPR-III) facility. The development of these damage equivalence techniques is necessary since SPR-III was shutdown in late 2006. As part of this effort, the late time {gamma}-ray sensitivity of a single diffusion lot of 2N2222A transistors has been characterized using one of the {sup 60}Co irradiation cells at the SNL Gamma Irradiation Facility (GIF). This report summarizes the results of the experiments performed at the GIF.

  1. 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.

  2. Sensitivity analysis of flux determination in heart by H₂ ¹⁸O -provided labeling using a dynamic Isotopologue model of energy transfer pathways.

    Science.gov (United States)

    Schryer, David W; Peterson, Pearu; Illaste, Ardo; Vendelin, Marko

    2012-01-01

    To characterize intracellular energy transfer in the heart, two organ-level methods have frequently been employed: ³¹P − NMR inversion and saturation transfer, and dynamic ¹⁸O labeling. Creatine kinase (CK) fluxes obtained by following oxygen labeling have been considerably smaller than the fluxes determined by ³¹P − NMR saturation transfer. It has been proposed that dynamic ¹⁸O labeling determines net flux through CK shuttle, whereas ³¹P − NMR saturation transfer measures total unidirectional flux. However, to our knowledge, no sensitivity analysis of flux determination by oxygen labeling has been performed, limiting our ability to compare flux distributions predicted by different methods. Here we analyze oxygen labeling in a physiological heart phosphotransfer network with active CK and adenylate kinase (AdK) shuttles and establish which fluxes determine the labeling state. A mathematical model consisting of a system of ordinary differential equations was composed describing ¹⁸O enrichment in each phosphoryl group and inorganic phosphate. By varying flux distributions in the model and calculating the labeling, we analyzed labeling sensitivity to different fluxes in the heart. We observed that the labeling state is predominantly sensitive to total unidirectional CK and AdK fluxes and not to net fluxes. We conclude that measuring dynamic incorporation of ¹⁸O into the high-energy phosphotransfer network in heart does not permit unambiguous determination of energetic fluxes with a higher magnitude than the ATP synthase rate when the bidirectionality of fluxes is taken into account. Our analysis suggests that the flux distributions obtained using dynamic ¹⁸O labeling, after removing the net flux assumption, are comparable with those from ³¹P − NMR inversion and saturation transfer.

  3. 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.

  4. Towards a simple and sensitive size-density fractionation approach for determining changes in soil organic matter

    Science.gov (United States)

    Guidi, Claudia; Magid, Jakob; Rodeghiero, Mirco

    2017-04-01

    Fractionation of soil organic matter (SOM), i.e. the separation of SOM into discrete fractions, can elucidate the temporal responses of soil organic carbon (SOC) to land-use and management changes. In order to reduce the workload and uncertainties associated with fractionation, we optimized and tested a simple size-density fractionation approach, containing a limited number of fractions and using relatively mild soil dispersion. We compared size-density fractionation, which isolated non-occluded particulate organic matter (POM), stable aggregates and silt- and clay-sized fraction, with aggregate size fractionation, i.e. an established method for aggregate separation, and with SOC content in the bulk soil. These methods were tested on soil samples collected from the mineral soil (0-20 cm) of a land-use and management gradient examining forest colonization on grassland in the Southern Alps (Italy). Differences in SOC stocks among successional stages were detected both by size-density fractions, aggregate size fractions and SOC content in the bulk soil. However, size-density fractions were better suited than aggregate size fractions for the detection of changes in SOC allocation within the study area. Therefore, the tested size-density fractionation approach may be preferred over aggregate size fractionation, considering its higher sensitivity to SOC differences in the land-use gradient. Stable aggregates obtained by size-density fractionation detected both changes in SOC allocation and stocks, and have the potential to be used as indicators of SOC changes in soils that express aggregate hierarchy. Further testing of the developed procedure across soil types, environmental conditions and land uses is required to confirm its repeatability and sensitivity to SOC changes.

  5. p53 and p21 determine the sensitivity of noscapine-induced apoptosis in colon cancer cells.

    Science.gov (United States)

    Aneja, Ritu; Ghaleb, Amr M; Zhou, Jun; Yang, Vincent W; Joshi, Harish C

    2007-04-15

    We have previously discovered the naturally occurring antitussive alkaloid noscapine as a tubulin-binding agent that attenuates microtubule dynamics and arrests mammalian cells at mitosis via activation of the c-Jun NH(2)-terminal kinase pathway. It is well established that the p53 protein plays a crucial role in the control of tumor cell response to chemotherapeutic agents and DNA-damaging agents; however, the relationship between p53-driven genes and drug sensitivity remains controversial. In this study, we compared chemosensitivity, cell cycle distribution, and apoptosis on noscapine treatment in four cell lines derived from the colorectal carcinoma HCT116 cells: p53(+/+) (p53-wt), p53(-/-) (p53-null), p21(-/-) (p21-null), and BAX(-/-) (BAX-null). Using these isogenic variants, we investigated the roles of p53, BAX, and p21 in the cellular response to treatment with noscapine. Our results show that noscapine treatment increases the expression of p53 over time in cells with wild-type p53 status. This increase in p53 is associated with an increased apoptotic BAX/Bcl-2 ratio consistent with increased sensitivity of these cells to apoptotic stimuli. Conversely, loss of p53 and p21 alleles had a counter effect on both BAX and Bcl-2 expression and the p53-null and p21-null cells were significantly resistant to the antiproliferative and apoptotic effects of noscapine. All but the p53-null cells displayed p53 protein accumulation in a time-dependent manner on noscapine treatment. Interestingly, despite increased levels of p53, p21-null cells were resistant to apoptosis, suggesting a proapoptotic role of p21 and implying that p53 is a necessary but not sufficient condition for noscapine-mediated apoptosis.

  6. Estimated secondary structure propensities within V1/V2 region of HIV gp120 are an important global antibody neutralization sensitivity determinant.

    Directory of Open Access Journals (Sweden)

    Maxim Totrov

    Full Text Available BACKGROUND: Neutralization sensitivity of HIV-1 virus to antibodies and anti-sera varies greatly between the isolates. Significant role of V1/V2 domain as a global neutralization sensitivity regulator has been suggested. Recent X-ray structures revealed presence of well-defined tertiary structure within this domain but also demonstrated partial disorder and conformational heterogeneity. METHODS: Correlations of neutralization sensitivity with the conformational propensities for beta-strand and alpha-helix formation over the entire folded V1/V2 domain as well as within sliding 5-residue window were investigated. Analysis was based on a set of neutralization data for 106 HIV isolates for which consistent neutralization sensitivity measurements against multiple pools of human immune sera have been previously reported. RESULTS: Significant correlation between beta-sheet formation propensity of the folded segments of V1/V2 domain and neutralization sensitivity was observed. Strongest correlation peaks localized to the beta-strands B and C. Correlation persisted when subsets of HIV isolates belonging to clades B, C and circulating recombinant form BC where analyzed individually or in combinations. CONCLUSIONS: Observed correlations suggest that stability of the beta-sheet structure and/or degree of structural disorder in the V1/V2 domain is an important determinant of the global neutralization sensitivity of HIV-1 virus. While specific mechanism is to yet to be investigated, plausible hypothesis is that less ordered V1/V2s may have stronger masking effect on various neutralizing epitopes, perhaps effectively occupying larger volume and thereby occluding antibody access.

  7. 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.

  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. 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.

  10. Determination of the effects of water adsorption on the sensitivity and detonation performance of the explosive JOB-9003 by molecular dynamics simulation.

    Science.gov (United States)

    Hang, GuiYun; Yu, WenLi; Wang, Tao; Li, Zhen

    2016-11-01

    In order to determine the adsorption mechanism of water on the crystal surfaces of the explosive JOB-9003 and the effect of this adsorption on the sensitivity and detonation performance of this explosive, a model of the crystal of JOB-9003 was created in the software package Materials Studio (MS). The adsorption process was simulated, and molecular dynamics simulation was performed with the COMPASS force field in the NPT ensemble to calculate the sensitivity and detonation performance of the explosive. The results show that the maximum trigger bond length decreases whereas the interaction energy of the trigger bond and the cohesive energy density increase after adsorption, indicating that the sensitivity of JOB-9003 decreases. The results for the detonation performance show that the detonation pressure, detonation velocity, and detonation heat decrease upon the adsorption of water, thus illustrating that the detonation performance of JOB-9003 is degraded. In summary, the adsorption of water has a positive effect on the sensitivity and safety of the explosive JOB-9003 but a negative effect on its detonation performance.

  11. 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.

    Science.gov (United States)

    de Oliveira, Marcelo Antonio; Pires, Fábio Ribeiro; Ferraço, Mariana; Belo, Alessandra Ferreira

    2014-07-28

    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.

  12. 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.

  13. Improving Research for Low Temperature Fluidity of Biodiesel%生物柴油低温流动性能的改进研究

    Institute of Scientific and Technical Information of China (English)

    李法社; 杜威; 包桂蓉; 王华; 李明; 苏成帅; 杨梅

    2014-01-01

    以地沟油和橡胶籽油为原料,制备相应生物柴油,测定其物化性能指标,地沟油生物柴油与橡胶籽油生物柴油的凝点与冷滤点分别是3℃、-1℃和6℃、2℃,40℃时运动粘度分别为5.78 mm2/s和5.0 mm2/s,其低温流动性能较差,严重影响了生物柴油使用和发展.考察了降凝剂I和降凝剂II对地沟油生物柴油与橡胶籽油生物柴油的低温流动性能,采用与低温流动特性较好的0#柴油调合混配可改进生物柴油低温流动特性,使生物柴油的凝点、冷滤点和运动粘度都能很好地得到改进.添加带有支链的油酸异丙酯可以很好地改进生物柴油的低温性能,但会使生物柴油运动粘度升高,选取适当的调合比例可以很好地改进生物柴油的低温流动性能.%Ditch oil and rubber see d oil are used as raw material to prepare correspondingbiodiesel,whose physi-cal and chemical performance index are then measured.The solidifying point and cold filter plugging point of ditch oil biodiesel is 3℃and 6℃.The solidifying point and cold filter plugging point of rubber seed oil biodiesel is-1℃ and 2℃.The kinematic viscosity at 40℃ is 5.78mm2/s and 5.0mm2/s.Their poor low temperature fluidity seriously has significant negative influence on the usage and development of biodiesel.Based on the per-formance of pour point depressant I and pour point depressant II to the low temperature fluidity of ditch oil biodiesel and rubber seed oil biodiesel,the low temperature fluidity of biodiesel is improved when mixed with 0#diesel oil whose low temperature fluidity is better,making the solidifying point,cold filter plugging point and ki-nematic viscosity of biodiesel improve greatly.Blending oleic acid isopropyl ester with branched chain can im-prove the low temperature fluidity of biodiesel greatly while making kinematic viscosity of biodiesel rise.Choosing proper blending ratio can improve the low