WorldWideScience

Sample records for determining optimal sampling

  1. Determination and optimization of spatial samples for distributed measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Xiaoming (Georgia Institute of Technology, Atlanta, GA); Tran, Hy D.; Shilling, Katherine Meghan; Kim, Heeyong (Georgia Institute of Technology, Atlanta, GA)

    2010-10-01

    There are no accepted standards for determining how many measurements to take during part inspection or where to take them, or for assessing confidence in the evaluation of acceptance based on these measurements. The goal of this work was to develop a standard method for determining the number of measurements, together with the spatial distribution of measurements and the associated risks for false acceptance and false rejection. Two paths have been taken to create a standard method for selecting sampling points. A wavelet-based model has been developed to select measurement points and to determine confidence in the measurement after the points are taken. An adaptive sampling strategy has been studied to determine implementation feasibility on commercial measurement equipment. Results using both real and simulated data are presented for each of the paths.

  2. Determination of Optimal Double Sampling Plan using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Sampath Sundaram

    2012-03-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Designing double sampling plan requires identification of sample sizes and acceptance numbers. In this paper a genetic algorithm has been designed for the selection of optimal acceptance numbers and sample sizes for the specified producer’s risk and consumer’s risk. Implementation of the algorithm has been illustrated numerically for different choices of quantities involved in a double sampling plan   

  1. Determining Optimal Decision Version

    Directory of Open Access Journals (Sweden)

    Olga Ioana Amariei

    2014-06-01

    Full Text Available In this paper we start from the calculation of the product cost, applying the method of calculating the cost of hour- machine (THM, on each of the three cutting machines, namely: the cutting machine with plasma, the combined cutting machine (plasma and water jet and the cutting machine with a water jet. Following the calculation of cost and taking into account the precision of manufacturing of each machine, as well as the quality of the processed surface, the optimal decisional version needs to be determined regarding the product manufacturing. To determine the optimal decisional version, we resort firstly to calculating the optimal version on each criterion, and then overall using multiattribute decision methods.

  2. β-NMR sample optimization

    CERN Document Server

    Zakoucka, Eva

    2013-01-01

    During my summer student programme I was working on sample optimization for a new β-NMR project at the ISOLDE facility. The β-NMR technique is well-established in solid-state physics and just recently it is being introduced for applications in biochemistry and life sciences. The β-NMR collaboration will be applying for beam time to the INTC committee in September for three nuclei: Cu, Zn and Mg. Sample optimization for Mg was already performed last year during the summer student programme. Therefore sample optimization for Cu and Zn had to be completed as well for the project proposal. My part in the project was to perform thorough literature research on techniques studying Cu and Zn complexes in native conditions, search for relevant binding candidates for Cu and Zn applicable for ß-NMR and eventually evaluate selected binding candidates using UV-VIS spectrometry.

  3. Multiple response optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry with sample injection as detergent emulsion

    International Nuclear Information System (INIS)

    Brum, Daniel M.; Lima, Claudio F.; Robaina, Nicolle F.; Fonseca, Teresa Cristina O.; Cassella, Ricardo J.

    2011-01-01

    The present paper reports the optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry (GF AAS) employing a strategy based on the injection of the samples as detergent emulsions. The method was optimized in relation to the experimental conditions for the emulsion formation and taking into account that the three analytes (Cu, Fe and Pb) should be measured in the same emulsion. The optimization was performed in a multivariate way by employing a three-variable Doehlert design and a multiple response strategy. For this purpose, the individual responses of the three analytes were combined, yielding a global response that was employed as a dependent variable. The three factors related to the optimization process were: the concentration of HNO 3 , the concentration of the emulsifier agent (Triton X-100 or Triton X-114) in aqueous solution used to emulsify the sample and the volume of solution. At optimum conditions, it was possible to obtain satisfactory results with an emulsion formed by mixing 4 mL of the samples with 1 mL of a 4.7% w/v Triton X-100 solution prepared in 10% v/v HNO 3 medium. The resulting emulsion was stable for 250 min, at least, and provided enough sensitivity to determine the three analytes in the five samples tested. A recovery test was performed to evaluate the accuracy of the optimized procedure and recovery rates, in the range of 88-105%; 94-118% and 95-120%, were verified for Cu, Fe and Pb, respectively.

  4. Multiple response optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry with sample injection as detergent emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Brum, Daniel M.; Lima, Claudio F. [Departamento de Quimica, Universidade Federal de Vicosa, A. Peter Henry Rolfs s/n, Vicosa/MG, 36570-000 (Brazil); Robaina, Nicolle F. [Departamento de Quimica Analitica, Universidade Federal Fluminense, Outeiro de S.J. Batista s/n, Centro, Niteroi/RJ, 24020-141 (Brazil); Fonseca, Teresa Cristina O. [Petrobras, Cenpes/PDEDS/QM, Av. Horacio Macedo 950, Ilha do Fundao, Rio de Janeiro/RJ, 21941-915 (Brazil); Cassella, Ricardo J., E-mail: cassella@vm.uff.br [Departamento de Quimica Analitica, Universidade Federal Fluminense, Outeiro de S.J. Batista s/n, Centro, Niteroi/RJ, 24020-141 (Brazil)

    2011-05-15

    The present paper reports the optimization for Cu, Fe and Pb determination in naphtha by graphite furnace atomic absorption spectrometry (GF AAS) employing a strategy based on the injection of the samples as detergent emulsions. The method was optimized in relation to the experimental conditions for the emulsion formation and taking into account that the three analytes (Cu, Fe and Pb) should be measured in the same emulsion. The optimization was performed in a multivariate way by employing a three-variable Doehlert design and a multiple response strategy. For this purpose, the individual responses of the three analytes were combined, yielding a global response that was employed as a dependent variable. The three factors related to the optimization process were: the concentration of HNO{sub 3}, the concentration of the emulsifier agent (Triton X-100 or Triton X-114) in aqueous solution used to emulsify the sample and the volume of solution. At optimum conditions, it was possible to obtain satisfactory results with an emulsion formed by mixing 4 mL of the samples with 1 mL of a 4.7% w/v Triton X-100 solution prepared in 10% v/v HNO{sub 3} medium. The resulting emulsion was stable for 250 min, at least, and provided enough sensitivity to determine the three analytes in the five samples tested. A recovery test was performed to evaluate the accuracy of the optimized procedure and recovery rates, in the range of 88-105%; 94-118% and 95-120%, were verified for Cu, Fe and Pb, respectively.

  5. Optimization of microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Soylak, Mustafa; Tuzen, Mustafa; Souza, Anderson Santos; Korn, Maria das Gracas Andrade; Ferreira, Sergio Luis Costa

    2007-01-01

    The present paper describes the development of a microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry (FAAS). The optimization step was performed using a full factorial design (2 3 ) involving the factors: composition of the acid mixture (CMA), microwave power (MP) and radiation time (RT). The experiments of this factorial were carried out using a certified reference material of tea GBW 07605 furnished by National Research Centre for Certified Reference Materials, China, being the metal recoveries considered as response. The relative standard deviations of the method were found below 8% for the three elements. The procedure proposed was used for the determination of copper, zinc and nickel in several samples of tea from Turkey. For 10 tea samples analyzed, the concentration achieved for copper, zinc and nickel varied at 6.4-13.1, 7.0-16.5 and 3.1-5.7 (μg g -1 ), respectively

  6. Optimization of a method based on micro-matrix solid-phase dispersion (micro-MSPD for the determination of PCBs in mussel samples

    Directory of Open Access Journals (Sweden)

    Nieves Carro

    2017-03-01

    Full Text Available This paper reports the development and optimization of micro-matrix solid-phase dispersion (micro-MSPD of nine polychlorinated biphenyls (PCBs in mussel samples (Mytilus galloprovincialis by using a two-level factorial design. Four variables (amount of sample, anhydrous sodium sulphate, Florisil and solvent volume were considered as factors in the optimization process. The results suggested that only the interaction between the amount of anhydrous sodium sulphate and the solvent volume was statistically significant for the overall recovery of a trichlorinated compound, CB 28. Generally most of the considered species exhibited a similar behaviour, the sample and Florisil amounts had a positive effect on PCBs extractions and solvent volume and sulphate amount had a negative effect. The analytical determination and confirmation of PCBs were carried out by using GC-ECD and GC-MS/MS, respectively. The method was validated having satisfactory precision and accuracy with RSD values below 6% and recoveries between 81 and 116% for all congeners. The optimized method was applied to the extraction of real mussel samples from two Galician Rías.

  7. Determination of As, Cd, and Pb in Tap Water and Bottled Water Samples by Using Optimized GFAAS System with Pd-Mg and Ni as Matrix Modifiers

    Directory of Open Access Journals (Sweden)

    Sezgin Bakırdere

    2013-01-01

    Full Text Available Arsenic, lead, and cadmium were determined in tap and bottled water samples consumed in the west part of Turkey at trace levels. Graphite furnace atomic absorption spectrometry (GFAAS was used in all detections. All of the system parameters for each element were optimized to increase sensitivity. Pd-Mg mixture was selected as the best matrix modifier for As, while the highest signals were obtained for Pb and Cd in the case of Ni used as matrix modifier. Detection limits for As, Cd, and Pb were found to be 2.0, 0.036, and 0.25 ng/mL, respectively. 78 tap water and 17 different brands of bottled water samples were analyzed for their As, Cd, and Pb contents under the optimized conditions. In all water samples, concentration of cadmium was found to be lower than detection limits. Lead concentration in the samples analyzed varied between N.D. and 12.66 ± 0.68 ng/mL. The highest concentration of arsenic was determined as 11.54 ± 2.79 ng/mL. Accuracy of the methods was verified by using a certified reference material, namely, Trace Element in Water, 1643e. Results found for As, Cd, and Pb in reference materials were in satisfactory agreement with the certified values.

  8. EXPERIMENTS TOWARDS DETERMINING BEST TRAINING SAMPLE SIZE FOR AUTOMATED EVALUATION OF DESCRIPTIVE ANSWERS THROUGH SEQUENTIAL MINIMAL OPTIMIZATION

    Directory of Open Access Journals (Sweden)

    Sunil Kumar C

    2014-01-01

    Full Text Available With number of students growing each year there is a strong need to automate systems capable of evaluating descriptive answers. Unfortunately, there aren’t many systems capable of performing this task. In this paper, we use a machine learning tool called LightSIDE to accomplish auto evaluation and scoring of descriptive answers. Our experiments are designed to cater to our primary goal of identifying the optimum training sample size so as to get optimum auto scoring. Besides the technical overview and the experiments design, the paper also covers challenges, benefits of the system. We also discussed interdisciplinary areas for future research on this topic.

  9. Use of constrained mixture design for optimization of method for determination of zinc and manganese in tea leaves employing slurry sampling

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Bezerra, Marcos, E-mail: mbezerra47@yahoo.com.br [Universidade Estadual do Sudoeste da Bahia, Laboratorio de Quimica Analitica, 45200-190, Jequie, Bahia (Brazil); Teixeira Castro, Jacira [Universidade Federal do Reconcavo da Bahia, Centro de Ciencias Exatas e Tecnologicas, 44380-000, Cruz das Almas, Bahia (Brazil); Coelho Macedo, Reinaldo; Goncalves da Silva, Douglas [Universidade Estadual do Sudoeste da Bahia, Laboratorio de Quimica Analitica, 45200-190, Jequie, Bahia (Brazil)

    2010-06-18

    A slurry suspension sampling technique has been developed for manganese and zinc determination in tea leaves by using flame atomic absorption spectrometry. The proportions of liquid-phase of the slurries composed by HCl, HNO{sub 3} and Triton X-100 solutions have been optimized applying a constrained mixture design. The optimized conditions were 200 mg of sample ground in a tungsten carbide balls mill (particle size < 100 {mu}m), dilution in a liquid-phase composed by 2.0 mol L{sup -1} nitric, 2.0 mol L{sup -1} hydrochloric acid and 2.5% Triton X-100 solutions (in the proportions of 50%, 12% and 38% respectively), sonication time of 10 min and final slurry volume of 50.0 mL. This method allowed the determination of manganese and zinc by FAAS, with detection limits of 0.46 and 0.66 {mu}g g{sup -1}, respectively. The precisions, expressed as relative standard deviation (RSD), are 6.9 and 5.5% (n = 10), for concentrations of manganese and zinc of 20 and 40 {mu}g g{sup -1}, respectively. The accuracy of the method was confirmed by analysis of the certified apple leaves (NIST 1515) and spinach leaves (NIST 1570a). The proposed method was applied for the determination of manganese and zinc in tea leaves used for the preparation of infusions. The obtained concentrations varied between 42 and 118 {mu}g g{sup -1} and 18.6 and 90 {mu}g g{sup -1}, respectively, for manganese and zinc. The results were compared with those obtained by an acid digestion procedure and determination of the elements by FAAS. There was no significant difference between the results obtained by the two methods based on a paired t-test (at 95% confidence level).

  10. Highly selective solid phase extraction and preconcentration of Azathioprine with nano-sized imprinted polymer based on multivariate optimization and its trace determination in biological and pharmaceutical samples

    International Nuclear Information System (INIS)

    Davarani, Saied Saeed Hosseiny; Rezayati zad, Zeinab; Taheri, Ali Reza; Rahmatian, Nasrin

    2017-01-01

    In this research, for first time selective separation and determination of Azathioprine is demonstrated using molecularly imprinted polymer as the solid-phase extraction adsorbent, measured by spectrophotometry at λ max 286 nm. The selective molecularly imprinted polymer was produced using Azathioprine and methacrylic acid as a template molecule and monomer, respectively. A molecularly imprinted solid-phase extraction procedure was performed in column for the analyte from pharmaceutical and serum samples. The synthesized polymers were characterized by infrared spectroscopy (IR), field emission scanning electron microscopy (FESEM). In order to investigate the effect of independent variables on the extraction efficiency, the response surface methodology (RSM) based on Box–Behnken design (BBD) was employed. The analytical parameters such as precision, accuracy and linear working range were also determined in optimal experimental conditions and the proposed method was applied to analysis of Azathioprine. The linear dynamic range and limits of detection were 2.5–0.01 and 0.008 mg L ‐1 respectively. The recoveries for analyte were higher than 95% and relative standard deviation values were found to be in the range of 0.83–4.15%. This method was successfully applied for the determination of Azathioprine in biological and pharmaceutical samples. - Graphical abstract: A new-nano sized imprinted polymer was synthesized and applied as sorbent in SPE in order to selective recognition, preconcentration, and determination of Azathioprine with the response surface methodology based on Box–Behnken design and was successfully investigated for the clean-up of human blood serum and pharmaceutical samples. - Highlights: • The nanosized-imprinted polymer has been synthesized by precipitation polymerization technique. • A molecularly imprinted solid-phase extraction procedure was performed for determination of Azathioprine. • The Azathioprine-molecular imprinting

  11. Optimization of a radiochemistry method for plutonium determination in biological samples; Optimizacion del metodo radioquimico para determinar plutonio en muestras biologicas

    Energy Technology Data Exchange (ETDEWEB)

    Cerchetti, Maria L; Arguelles, Maria G [Comision Nacional de Energia Atomica, Ezeiza (Argentina). Laboratorio de Dosimetria Personal y de Area

    2005-07-01

    Plutonium has been widely used for civilian an military activities. Nevertheless, the methods to control work exposition have not evolved in the same way, remaining as one of the major challengers for the radiological protection practice. Due to the low acceptable incorporation limit, the usual determination is based on indirect methods in urine samples. Our main objective was to optimize a technique used to monitor internal contamination of workers exposed to Plutonium isotopes. Different parameters were modified and their influence on the three steps of the method was evaluated. Those which gave the highest yield and feasibility were selected. The method involves: 1-) Sample concentration (coprecipitation); 2-) Plutonium purification; and 3-) Source preparation by electrodeposition. On the coprecipitation phase, changes on temperature and concentration of the carrier were evaluated. On the ion-exchange separation, changes on the type of the resin, elution solution for hydroxylamine (concentration and volume), length and column recycle were evaluated. Finally, on the electrodeposition phase, we modified the following: electrolytic solution, pH and time. Measures were made by liquid scintillation counting and alpha spectrometry (PIPS). We obtained the following yields: 88% for coprecipitation (at 60 C degree with 2 ml of CaHPO{sub 4}), 71% for ion-exchange (resins AG 1x8 Cl{sup -} 100-200 mesh, hydroxylamine 0.1N in HCl 0.2N as eluent, column between 4.5 and 8 cm), and 93% for electrodeposition (H{sub 2}SO{sub 4}-NH{sub 4}OH, 100 minutes and pH from 2 to 2.8). The expand uncertainty was 30% (NC 95%), the decision threshold (Lc) was 0.102 Bq/L and the minimum detectable activity was 0.218 Bq/L of urine. We obtained an optimized method to screen workers exposed to Plutonium. (author)

  12. [Determination of 51 carbamate pesticide residues in vegetables by liquid chromatography-tandem mass spectrometry based on optimization of QuEChERS sample preparation method].

    Science.gov (United States)

    Wang, Lianzhu; Zhou, Yu; Huang, Xiaoyan; Wang, Ruilong; Lin, Zixu; Chen, Yong; Wang, Dengfei; Lin, Dejuan; Xu, Dunming

    2013-12-01

    The raw extracts of six vegetables (tomato, green bean, shallot, broccoli, ginger and carrot) were analyzed using gas chromatography-mass spectrometry (GC-MS) in full scan mode combined with NIST library search to confirm main matrix compounds. The effects of cleanup and adsorption mechanisms of primary secondary amine (PSA) , octadecylsilane (C18) and PSA + C18 on co-extractives were studied by the weight of evaporation residue for extracts before and after cleanup. The suitability of the two versions of QuEChERS method for sample preparation was evaluated for the extraction of 51 carbamate pesticides in the six vegetables. One of the QuEChERS methods was the original un-buffered method published in 2003, and the other was AOAC Official Method 2007.01 using acetate buffer. As a result, the best effects were obtained from using the combination of C18 and PSA for extract cleanup in vegetables. The acetate-buffered version was suitable for the determination of all pesticides except dioxacarb. Un-buffered QuEChERS method gave satisfactory results for determining dioxacarb. Based on these results, the suitable QuEChERS sample preparation method and liquid chromatography-positive electrospray ionization-tandem mass spectrometry under the optimized conditions were applied to determine the 51 carbamate pesticide residues in six vegetables. The analytes were quantified by matrix-matched standard solution. The recoveries at three levels of 10, 20 and 100 microg/kg spiked in six vegetables ranged from 58.4% to 126% with the relative standard deviations of 3.3%-26%. The limits of quantification (LOQ, S/N > or = 10) were 0.2-10 microg/kg except that the LOQs of cartap and thiofanox were 50 microg/kg. The method is highly efficient, sensitive and suitable for monitoring the 51 carbamate pesticide residues in vegetables.

  13. Highly selective solid phase extraction and preconcentration of Azathioprine with nano-sized imprinted polymer based on multivariate optimization and its trace determination in biological and pharmaceutical samples

    Energy Technology Data Exchange (ETDEWEB)

    Davarani, Saied Saeed Hosseiny, E-mail: ss-hosseiny@cc.sbu.ac.ir [Faculty of Chemistry, Shahid Beheshti University, G. C., P.O. Box 19839-4716, Tehran (Iran, Islamic Republic of); Rezayati zad, Zeinab [Faculty of Chemistry, Shahid Beheshti University, G. C., P.O. Box 19839-4716, Tehran (Iran, Islamic Republic of); Taheri, Ali Reza; Rahmatian, Nasrin [Islamic Azad University, Ilam Branch, Ilam (Iran, Islamic Republic of)

    2017-02-01

    In this research, for first time selective separation and determination of Azathioprine is demonstrated using molecularly imprinted polymer as the solid-phase extraction adsorbent, measured by spectrophotometry at λ{sub max} 286 nm. The selective molecularly imprinted polymer was produced using Azathioprine and methacrylic acid as a template molecule and monomer, respectively. A molecularly imprinted solid-phase extraction procedure was performed in column for the analyte from pharmaceutical and serum samples. The synthesized polymers were characterized by infrared spectroscopy (IR), field emission scanning electron microscopy (FESEM). In order to investigate the effect of independent variables on the extraction efficiency, the response surface methodology (RSM) based on Box–Behnken design (BBD) was employed. The analytical parameters such as precision, accuracy and linear working range were also determined in optimal experimental conditions and the proposed method was applied to analysis of Azathioprine. The linear dynamic range and limits of detection were 2.5–0.01 and 0.008 mg L{sup ‐1} respectively. The recoveries for analyte were higher than 95% and relative standard deviation values were found to be in the range of 0.83–4.15%. This method was successfully applied for the determination of Azathioprine in biological and pharmaceutical samples. - Graphical abstract: A new-nano sized imprinted polymer was synthesized and applied as sorbent in SPE in order to selective recognition, preconcentration, and determination of Azathioprine with the response surface methodology based on Box–Behnken design and was successfully investigated for the clean-up of human blood serum and pharmaceutical samples. - Highlights: • The nanosized-imprinted polymer has been synthesized by precipitation polymerization technique. • A molecularly imprinted solid-phase extraction procedure was performed for determination of Azathioprine. • The Azathioprine

  14. The optimal sampling of outsourcing product

    International Nuclear Information System (INIS)

    Yang Chao; Pei Jiacheng

    2014-01-01

    In order to improve quality and cost, the sampling c = 0 has been introduced to the inspection of outsourcing product. According to the current quality level (p = 0.4%), we confirmed the optimal sampling that is: Ac = 0; if N ≤ 3000, n = 55; 3001 ≤ N ≤ 10000, n = 86; N ≥ 10001, n = 108. Through analyzing the OC curve, we came to the conclusion that when N ≤ 3000, the protective ability of optimal sampling for product quality is stronger than current sampling. Corresponding to the same 'consumer risk', the product quality of optimal sampling is superior to current sampling. (authors)

  15. Optimization of sample preparation and chromatography for the determination of perfluoroalkyl acids in sediments from the Yangtze Estuary and East China Sea.

    Science.gov (United States)

    Wang, Qian-Wen; Yang, Gui-Peng; Zhang, Ze-Ming; Zhang, Jing

    2018-08-01

    Perfluoroalkyl acids (PFAAs) are ubiquitous pollutants present in various environmental media, including marine sediments. A method was proposed for the determination of 17 target PFAA analytes in marine sediment samples (n = 49) collected from the Yangtze Estuary and East China Sea. The proposed method involves the use of an optimized pretreatment procedure and ultrahigh-performance liquid chromatography electrospray ionization-tandem mass spectrometry in dynamic multiple reaction monitoring mode. The method relied on extraction cycles using methanol followed by concentration, filtration, and small volume injection to UHPLC-MS/MS. The recovery, time efficiency, and detection limit of the proposed method are improved relative to those of traditional methods. Limits of detection varied from 0.003 to 0.045 ng/g, and spike recoveries to sediment ranged from 90% to 110% with suitable precisions (1.7%-14.6%). PFAAs were widely present in the samples, and ΣPFAAs ranged from 0.67 ng/g dw to 36.75 ng/g dw. Results indicated that terrigenous input strongly influences PFAA distribution in sediments from the study areas. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) were identified as the dominant perfluorocarboxylic acid (PFCA) and perfluoroalkylsulfonate (PFSA) in sediment samples from the Yangtze Estuary and the East China Sea. Preliminary environmental risk assessment indicated that PFOS may pose a higher environmental risk than PFOA. Furthermore, risk quotient values indicated that PFOS poses a significant risk to the aquatic ecosystem of the study areas. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Sodium sampling and impurities determination

    International Nuclear Information System (INIS)

    Docekal, J.; Kovar, C.; Stuchlik, S.

    1980-01-01

    Samples may be obtained from tubes in-built in the sodium facility and further processed or they are taken into crucibles, stored and processed later. Another sampling method is a method involving vacuum distillation of sodium, thus concentrating impurities. Oxygen is determined by malgamation, distillation or vanadium balance methods. Hydrogen is determined by the metal diaphragm extraction, direct extraction or amalgamation methods. Carbon is determined using dry techniques involving burning a sodium sample at 1100 degC or using wet techniques by dissolving the sample with an acid. Trace amounts of metal impurities are determined after dissolving sodium in ethanol. The trace metals are concentrated and sodium excess is removed. (M.S.)

  17. Sample size determination and power

    CERN Document Server

    Ryan, Thomas P, Jr

    2013-01-01

    THOMAS P. RYAN, PhD, teaches online advanced statistics courses for Northwestern University and The Institute for Statistics Education in sample size determination, design of experiments, engineering statistics, and regression analysis.

  18. Optimal sampling theory and population modelling - Application to determination of the influence of the microgravity environment on drug distribution and elimination

    Science.gov (United States)

    Drusano, George L.

    1991-01-01

    The optimal sampling theory is evaluated in applications to studies related to the distribution and elimination of several drugs (including ceftazidime, piperacillin, and ciprofloxacin), using the SAMPLE module of the ADAPT II package of programs developed by D'Argenio and Schumitzky (1979, 1988) and comparing the pharmacokinetic parameter values with results obtained by traditional ten-sample design. The impact of the use of optimal sampling was demonstrated in conjunction with NONMEM (Sheiner et al., 1977) approach, in which the population is taken as the unit of analysis, allowing even fragmentary patient data sets to contribute to population parameter estimates. It is shown that this technique is applicable in both the single-dose and the multiple-dose environments. The ability to study real patients made it possible to show that there was a bimodal distribution in ciprofloxacin nonrenal clearance.

  19. Square-wave anodic-stripping voltammetric determination of Cd, Pb and Cu in wine: Set-up and optimization of sample pre-treatment and instrumental parameters

    International Nuclear Information System (INIS)

    Illuminati, Silvia; Annibaldi, Anna; Truzzi, Cristina; Finale, Carolina; Scarponi, Giuseppe

    2013-01-01

    For the first time, square-wave anodic-stripping voltammetry (SWASV) was set up and optimized for the determination of Cd, Pb and Cu in white wine after UV photo-oxidative digestion of the sample. The best procedure for the sample pre-treatment consisted in a 6-h UV irradiation of diluted, acidified wine, with the addition of ultrapure H 2 O 2 (three sequential additions during the irradiation). Due to metal concentration differences, separate measurements were carried out for Cd (deposition potential −950 mV vs. Ag/AgCl/3 M KCl deposition time 15 min) and simultaneously for Pb and Cu (E d −750 mV, t d 30 s). The optimum set-up of the main instrumental parameters, evaluated also in terms of the signal-to-noise ratio, were as follows: E SW 20 mV, f 100 Hz, ΔE step 8 mV, t step 100 ms, t wait 60 ms, t delay 2 ms, t meas 3 ms. The electrochemical behaviour was reversible bielectronic for Cd and Pb, and kinetically controlled monoelectronic for Cu. Good accuracy was found both when the recovery procedure was used and when the results were compared with data obtained by differential pulse anodic stripping voltammetry. The linearity of the response was verified up to ∼4 μg L −1 for Cd and Pb and ∼15 μg L −1 for Cu. The detection limits for t d = 5 min in the 10 times diluted, UV digested sample were (ng L −1 ): Cd 7.0, Pb 1.2 and Cu 6.6, which are well below currently applied methods. Application to a Verdicchio dei Castelli di Jesi white wine revealed concentration levels of Cd ∼0.2, Pb ∼10, Cu ∼30 μg L −1 with repeatabilities of (±RSD%) Cd ±6%, Pb ±5%, Cu ±10%

  20. Designing optimal sampling schemes for field visits

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2008-10-01

    Full Text Available This is a presentation of a statistical method for deriving optimal spatial sampling schemes. The research focuses on ground verification of minerals derived from hyperspectral data. Spectral angle mapper (SAM) and spectral feature fitting (SFF...

  1. Concepts in sample size determination

    Directory of Open Access Journals (Sweden)

    Umadevi K Rao

    2012-01-01

    Full Text Available Investigators involved in clinical, epidemiological or translational research, have the drive to publish their results so that they can extrapolate their findings to the population. This begins with the preliminary step of deciding the topic to be studied, the subjects and the type of study design. In this context, the researcher must determine how many subjects would be required for the proposed study. Thus, the number of individuals to be included in the study, i.e., the sample size is an important consideration in the design of many clinical studies. The sample size determination should be based on the difference in the outcome between the two groups studied as in an analytical study, as well as on the accepted p value for statistical significance and the required statistical power to test a hypothesis. The accepted risk of type I error or alpha value, which by convention is set at the 0.05 level in biomedical research defines the cutoff point at which the p value obtained in the study is judged as significant or not. The power in clinical research is the likelihood of finding a statistically significant result when it exists and is typically set to >80%. This is necessary since the most rigorously executed studies may fail to answer the research question if the sample size is too small. Alternatively, a study with too large a sample size will be difficult and will result in waste of time and resources. Thus, the goal of sample size planning is to estimate an appropriate number of subjects for a given study design. This article describes the concepts in estimating the sample size.

  2. Optimization and analysis of a quantitative real-time PCR-based technique to determine microRNA expression in formalin-fixed paraffin-embedded samples

    Directory of Open Access Journals (Sweden)

    Reis Patricia P

    2010-06-01

    Full Text Available Abstract Background MicroRNAs (miRs are non-coding RNA molecules involved in post-transcriptional regulation, with diverse functions in tissue development, differentiation, cell proliferation and apoptosis. miRs may be less prone to degradation during formalin fixation, facilitating miR expression studies in formalin-fixed paraffin-embedded (FFPE tissue. Results Our study demonstrates that the TaqMan Human MicroRNA Array v1.0 (Early Access platform is suitable for miR expression analysis in FFPE tissue with a high reproducibility (correlation coefficients of 0.95 between duplicates, p 35, we show that reproducibility between technical replicates, equivalent dilutions, and FFPE vs. frozen samples is best in the high abundance stratum. We also demonstrate that the miR expression profiles of FFPE samples are comparable to those of fresh-frozen samples, with a correlation of up to 0.87 (p Conclusion Our study thus demonstrates the utility, reproducibility, and optimization steps needed in miR expression studies using FFPE samples on a high-throughput quantitative PCR-based miR platform, opening up a realm of research possibilities for retrospective studies.

  3. Optimal sampling schemes applied in geology

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2010-05-01

    Full Text Available Methodology 6 Results 7 Background and Research Question for Study 2 8 Study Area and Data 9 Methodology 10 Results 11 Conclusions Debba (CSIR) Optimal Sampling Schemes applied in Geology UP 2010 2 / 47 Outline 1 Introduction to hyperspectral remote... sensing 2 Objective of Study 1 3 Study Area 4 Data used 5 Methodology 6 Results 7 Background and Research Question for Study 2 8 Study Area and Data 9 Methodology 10 Results 11 Conclusions Debba (CSIR) Optimal Sampling Schemes applied in Geology...

  4. Optimal time points sampling in pathway modelling.

    Science.gov (United States)

    Hu, Shiyan

    2004-01-01

    Modelling cellular dynamics based on experimental data is at the heart of system biology. Considerable progress has been made to dynamic pathway modelling as well as the related parameter estimation. However, few of them gives consideration for the issue of optimal sampling time selection for parameter estimation. Time course experiments in molecular biology rarely produce large and accurate data sets and the experiments involved are usually time consuming and expensive. Therefore, to approximate parameters for models with only few available sampling data is of significant practical value. For signal transduction, the sampling intervals are usually not evenly distributed and are based on heuristics. In the paper, we investigate an approach to guide the process of selecting time points in an optimal way to minimize the variance of parameter estimates. In the method, we first formulate the problem to a nonlinear constrained optimization problem by maximum likelihood estimation. We then modify and apply a quantum-inspired evolutionary algorithm, which combines the advantages of both quantum computing and evolutionary computing, to solve the optimization problem. The new algorithm does not suffer from the morass of selecting good initial values and being stuck into local optimum as usually accompanied with the conventional numerical optimization techniques. The simulation results indicate the soundness of the new method.

  5. Optimization of chemical and instrumental parameters in hydride generation laser-induced breakdown spectrometry for the determination of arsenic, antimony, lead and germanium in aqueous samples.

    Science.gov (United States)

    Yeşiller, Semira Unal; Yalçın, Serife

    2013-04-03

    A laser induced breakdown spectrometry hyphenated with on-line continuous flow hydride generation sample introduction system, HG-LIBS, has been used for the determination of arsenic, antimony, lead and germanium in aqueous environments. Optimum chemical and instrumental parameters governing chemical hydride generation, laser plasma formation and detection were investigated for each element under argon and nitrogen atmosphere. Arsenic, antimony and germanium have presented strong enhancement in signal strength under argon atmosphere while lead has shown no sensitivity to ambient gas type. Detection limits of 1.1 mg L(-1), 1.0 mg L(-1), 1.3 mg L(-1) and 0.2 mg L(-1) were obtained for As, Sb, Pb and Ge, respectively. Up to 77 times enhancement in detection limit of Pb were obtained, compared to the result obtained from the direct analysis of liquids by LIBS. Applicability of the technique to real water samples was tested through spiking experiments and recoveries higher than 80% were obtained. Results demonstrate that, HG-LIBS approach is suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring in aqueous environments. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. The choice of ultrasound assisted extraction coupled with spectrophotometric for rapid determination of gallic acid in water samples: Central composite design for optimization of process variables.

    Science.gov (United States)

    Pooralhossini, Jaleh; Ghaedi, Mehrorang; Zanjanchi, Mohammad Ali; Asfaram, Arash

    2017-01-01

    A sensitive procedure namely ultrasound-assisted (UA) coupled dispersive nano solid-phase microextraction spectrophotometry (DNSPME-UV-Vis) was designed for preconcentration and subsequent determination of gallic acid (GA) from water samples, while the detailed of composition and morphology and also purity and structure of this new sorbent was identified by techniques like field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Energy-dispersive X-ray spectroscopy (EDX) techniques. Among conventional parameters viz. pH, amount of sorbent, sonication time and volume of elution solvent based on Response Surface Methodology (RSM) and central composite design according to statistics based contour the best operational conditions was set at pH of 2.0; 1.5mg sorbent, 4.0min sonication and 150μL ethanol. Under these pre-qualified conditions the method has linear response over wide concentration range of 15-6000ngmL -1 with a correlation coefficient of 0.9996. The good figure of merits like acceptable LOD (S/N=3) and LOQ (S/N=10) with numerical value of 2.923 and 9.744ngmL -1 , respectively and relative recovery between 95.54 and 100.02% show the applicability and efficiency of this method for real samples analysis with RSDs below 6.0%. Finally the method with good performance were used for monitoring under study analyte in various real samples like tap, river and mineral waters. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Determination of Pu in soil samples

    International Nuclear Information System (INIS)

    Torres C, C. O.; Hernandez M, H.; Romero G, E. T.; Vega C, H. R.

    2016-10-01

    The irreversible consequences of accidents occurring in nuclear plants and in nuclear fuel reprocessing sites are mainly the distribution of different radionuclides in different matrices such as the soil. The distribution in the superficial soil is related to the internal and external exposure to the radiation of the affected population. The internal contamination with radionuclides such as Pu is of great relevance to the nuclear forensic science, where is important to know the chemical and isotopic compositions of nuclear materials. The objective of this work is to optimize the radiochemical separation of plutonium (Pu) from soil samples and to determine their concentration. The soil samples were prepared using acid digestion assisted by microwave; purification of Pu was carried out with AG1X8 resin using ion exchange chromatography. Pu isotopes were measured using ICP-SFMS. In order to reduce the interference due to the presence of "2"3"8UH "+ in the samples, a solvent removal system (Apex) was used. In addition, the limit of detection and quantification of Pu was determined. It was found that the recovery efficiency of Pu in soil samples ranges from 70 to 93%. (Author)

  8. Sample Adaptive Offset Optimization in HEVC

    Directory of Open Access Journals (Sweden)

    Yang Zhang

    2014-11-01

    Full Text Available As the next generation of video coding standard, High Efficiency Video Coding (HEVC adopted many useful tools to improve coding efficiency. Sample Adaptive Offset (SAO, is a technique to reduce sample distortion by providing offsets to pixels in in-loop filter. In SAO, pixels in LCU are classified into several categories, then categories and offsets are given based on Rate-Distortion Optimization (RDO of reconstructed pixels in a Largest Coding Unit (LCU. Pixels in a LCU are operated by the same SAO process, however, transform and inverse transform makes the distortion of pixels in Transform Unit (TU edge larger than the distortion inside TU even after deblocking filtering (DF and SAO. And the categories of SAO can also be refined, since it is not proper for many cases. This paper proposed a TU edge offset mode and a category refinement for SAO in HEVC. Experimental results shows that those two kinds of optimization gets -0.13 and -0.2 gain respectively compared with the SAO in HEVC. The proposed algorithm which using the two kinds of optimization gets -0.23 gain on BD-rate compared with the SAO in HEVC which is a 47 % increase with nearly no increase on coding time.

  9. Optimization of a spectrometry for energy-dispersive x-ray fluorescence analysis by x-ray tube in combination with secondary target for multielements determination of sediment samples

    International Nuclear Information System (INIS)

    Zaidi Embong; Husin Wagiran

    1997-01-01

    The design of an energy-dispersive X-ray fluorescence spectrometer equipped with a conventional X-ray tube and secondary target is described. The spectrometer system constructed in our laboratory consists of a semiconductor detector system, irradiation chamber and X-ray tube. Primary source from X-ray tube was used to produced secondary X-ray from selenium, molybdenum and cadmium targets. The fluorescence X-ray from the sample was detected using Si(Li) detector with resolution of 0. 175 keV (Mn-K(x). The spectrometer was used for determination of multi-elements with atomic number between 20 to 44 in river sediment samples. The X-ray spectrum, from the samples were analysed using computer software which was developed based on Marquardt method. Optimal conditions and detection limits are determined experimentally by variation of excitation parameters for each combination of secondary target and tube voltage

  10. Ultrasound assisted combined molecularly imprinted polymer for selective extraction of nicotinamide in human urine and milk samples: Spectrophotometric determination and optimization study.

    Science.gov (United States)

    Asfaram, Arash; Ghaedi, Mehrorang; Dashtian, Kheibar

    2017-01-01

    Ultrasound-assisted dispersive solid phase microextraction followed by UV-vis spectrophotometer (UA-DSPME-UV-vis) was designed for extraction and preconcentration of nicotinamide (vitamin B 3 ) by HKUST-1 metal organic framework (MOF) based molecularly imprinted polymer (MIP). This new material was characterized by FTIR and FE-SEM techniques. The preliminary Plackett-Burman design was used for screening and subsequently the central composite design justifies significant terms and possible construction of mathematical equation which give the individual and cooperative contribution of variables like HKUST-1-MOF-NA-MIP mass, sonication time, temperature, eluent volume, pH and vortex time. Accordingly the optimum condition was set as: 2.0mg HKUST-1-MOF-NA-MIP, 200μL eluent and 5.0min sonication time in center points other variables were determined as the best conditions to reach the maximum recovery of the analyte. The UA-DSPME-UV-vis method performances like excellent linearity (LR), limits of detection (LOD), limits of quantification of 10-5000μgL -1 with R 2 of 0.99, LOD (1.96ngmL -1 ), LOQ (6.53μgL -1 ), respectively show successful and accurate applicability of the present method for monitoring analytes with within- and between-day precision of 0.96-3.38%. The average absolute recoveries of the nicotinamide extracted from the urine, milk and water samples were 95.85-101.27%. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Optimal sampling strategies for detecting zoonotic disease epidemics.

    Directory of Open Access Journals (Sweden)

    Jake M Ferguson

    2014-06-01

    Full Text Available The early detection of disease epidemics reduces the chance of successful introductions into new locales, minimizes the number of infections, and reduces the financial impact. We develop a framework to determine the optimal sampling strategy for disease detection in zoonotic host-vector epidemiological systems when a disease goes from below detectable levels to an epidemic. We find that if the time of disease introduction is known then the optimal sampling strategy can switch abruptly between sampling only from the vector population to sampling only from the host population. We also construct time-independent optimal sampling strategies when conducting periodic sampling that can involve sampling both the host and the vector populations simultaneously. Both time-dependent and -independent solutions can be useful for sampling design, depending on whether the time of introduction of the disease is known or not. We illustrate the approach with West Nile virus, a globally-spreading zoonotic arbovirus. Though our analytical results are based on a linearization of the dynamical systems, the sampling rules appear robust over a wide range of parameter space when compared to nonlinear simulation models. Our results suggest some simple rules that can be used by practitioners when developing surveillance programs. These rules require knowledge of transition rates between epidemiological compartments, which population was initially infected, and of the cost per sample for serological tests.

  12. Optimal sampling strategies for detecting zoonotic disease epidemics.

    Science.gov (United States)

    Ferguson, Jake M; Langebrake, Jessica B; Cannataro, Vincent L; Garcia, Andres J; Hamman, Elizabeth A; Martcheva, Maia; Osenberg, Craig W

    2014-06-01

    The early detection of disease epidemics reduces the chance of successful introductions into new locales, minimizes the number of infections, and reduces the financial impact. We develop a framework to determine the optimal sampling strategy for disease detection in zoonotic host-vector epidemiological systems when a disease goes from below detectable levels to an epidemic. We find that if the time of disease introduction is known then the optimal sampling strategy can switch abruptly between sampling only from the vector population to sampling only from the host population. We also construct time-independent optimal sampling strategies when conducting periodic sampling that can involve sampling both the host and the vector populations simultaneously. Both time-dependent and -independent solutions can be useful for sampling design, depending on whether the time of introduction of the disease is known or not. We illustrate the approach with West Nile virus, a globally-spreading zoonotic arbovirus. Though our analytical results are based on a linearization of the dynamical systems, the sampling rules appear robust over a wide range of parameter space when compared to nonlinear simulation models. Our results suggest some simple rules that can be used by practitioners when developing surveillance programs. These rules require knowledge of transition rates between epidemiological compartments, which population was initially infected, and of the cost per sample for serological tests.

  13. Resolution optimization with irregularly sampled Fourier data

    International Nuclear Information System (INIS)

    Ferrara, Matthew; Parker, Jason T; Cheney, Margaret

    2013-01-01

    Image acquisition systems such as synthetic aperture radar (SAR) and magnetic resonance imaging often measure irregularly spaced Fourier samples of the desired image. In this paper we show the relationship between sample locations, their associated backprojection weights, and image resolution as characterized by the resulting point spread function (PSF). Two new methods for computing data weights, based on different optimization criteria, are proposed. The first method, which solves a maximal-eigenvector problem, optimizes a PSF-derived resolution metric which is shown to be equivalent to the volume of the Cramer–Rao (positional) error ellipsoid in the uniform-weight case. The second approach utilizes as its performance metric the Frobenius error between the PSF operator and the ideal delta function, and is an extension of a previously reported algorithm. Our proposed extension appropriately regularizes the weight estimates in the presence of noisy data and eliminates the superfluous issue of image discretization in the choice of data weights. The Frobenius-error approach results in a Tikhonov-regularized inverse problem whose Tikhonov weights are dependent on the locations of the Fourier data as well as the noise variance. The two new methods are compared against several state-of-the-art weighting strategies for synthetic multistatic point-scatterer data, as well as an ‘interrupted SAR’ dataset representative of in-band interference commonly encountered in very high frequency radar applications. (paper)

  14. Determination of uranium in liquid samples

    International Nuclear Information System (INIS)

    Macefat, Martina R.; Grahek, Zeljko; Ivsic, Astrid G.

    2008-01-01

    Full text: Uranium is a natural occurring radionuclide and the first member of natural radioactive chains which makes its determination in natural materials interesting from geochemical and radioecological aspect. It can be quantitatively determined as element and/or its radioisotopes by different spectrometric methods (ICP-MS, spectrophotometry, alpha spectrometry). It is necessary to develop inexpensive, rapid and sensitive methods for the routine analysis. Therefore, in this paper, development of a new method for the isolation of uranium from liquid samples and subsequent determination by spectrophotometry and ICP-MS will be described. It is possible to isolate uranium from drinking and seawater using extraction chromatography or mixed solvent ion exchange. Uranium can be strongly bound on the TRU extraction chromatographic resin from nitric acid (chemical recovery is 100%) and can be separated from other interfering elements, while separation from thorium, which can be also strongly bound on this resin, is possible with hydrochloric acid. It is also possible to separate uranium from thorium on the anion exchanger Amberlite CG-400 (NO 3 - form) because uranium is much more weakly bound on this exchanger from alcoholic solutions of nitric acid. After the separation uranium is determined by ICP-MS and by spectrophotometric method with arsenazo III (λ max =652 nm). Developed method enables selection of the optimal mode of isolation for the given purposes. (author)

  15. Optimal sampling strategy for data mining

    International Nuclear Information System (INIS)

    Ghaffar, A.; Shahbaz, M.; Mahmood, W.

    2013-01-01

    Latest technology like Internet, corporate intranets, data warehouses, ERP's, satellites, digital sensors, embedded systems, mobiles networks all are generating such a massive amount of data that it is getting very difficult to analyze and understand all these data, even using data mining tools. Huge datasets are becoming a difficult challenge for classification algorithms. With increasing amounts of data, data mining algorithms are getting slower and analysis is getting less interactive. Sampling can be a solution. Using a fraction of computing resources, Sampling can often provide same level of accuracy. The process of sampling requires much care because there are many factors involved in the determination of correct sample size. The approach proposed in this paper tries to find a solution to this problem. Based on a statistical formula, after setting some parameters, it returns a sample size called s ufficient sample size , which is then selected through probability sampling. Results indicate the usefulness of this technique in coping with the problem of huge datasets. (author)

  16. Application and optimization of microwave-assisted extraction and dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for sensitive determination of polyamines in turkey breast meat samples.

    Science.gov (United States)

    Bashiry, Moein; Mohammadi, Abdorreza; Hosseini, Hedayat; Kamankesh, Marzieh; Aeenehvand, Saeed; Mohammadi, Zaniar

    2016-01-01

    A novel method based on microwave-assisted extraction and dispersive liquid-liquid microextraction (MAE-DLLME) followed by high-performance liquid chromatography (HPLC) was developed for the determination of three polyamines from turkey breast meat samples. Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the effective factors in DLLME process. The optimum microextraction efficiency was obtained under optimized conditions. The calibration graphs of the proposed method were linear in the range of 20-200 ng g(-1), with the coefficient determination (R(2)) higher than 0.9914. The relative standard deviations were 6.72-7.30% (n = 7). The limits of detection were in the range of 0.8-1.4 ng g(-1). The recoveries of these compounds in spiked turkey breast meat samples were from 95% to 105%. The increased sensitivity in using the MAE-DLLME-HPLC-UV has been demonstrated. Compared with previous methods, the proposed method is an accurate, rapid and reliable sample-pretreatment method. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Optimizing Sampling Efficiency for Biomass Estimation Across NEON Domains

    Science.gov (United States)

    Abercrombie, H. H.; Meier, C. L.; Spencer, J. J.

    2013-12-01

    with LAI and clip harvest data to determine whether LAI can be used as a suitable proxy for aboveground standing biomass. We also compared optimal sample sizes derived from LAI data, and clip-harvest data from two different size clip harvest areas (0.1m by 1m vs. 0.1m by 2m). Sample sizes were calculated in order to estimate the mean to within a standardized level of uncertainty that will be used to guide sampling effort across all vegetation types (i.e. estimated within × 10% with 95% confidence). Finally, we employed a Semivariogram approach to determine optimal sample size and spacing.

  18. Determination of tritium in wine yeast samples

    International Nuclear Information System (INIS)

    Cotarlea, Monica-Ionela; Paunescu Niculina; Galeriu, D; Mocanu, N.; Margineanu, R.; Marin, G.

    1998-01-01

    Analytical procedures were developed to determine tritium in wine and wine yeast samples. The content of organic compounds affecting the LSC measurement is reduced by fractioning distillation for wine samples and azeotropic distillation/fractional distillation for wine yeast samples. Finally, the water samples were normally distilled with K MO 4 . The established procedures were successfully applied for wine and wine samples from Murfatlar harvests of the years 1995 and 1996. (authors)

  19. Improved sample size determination for attributes and variables sampling

    International Nuclear Information System (INIS)

    Stirpe, D.; Picard, R.R.

    1985-01-01

    Earlier INMM papers have addressed the attributes/variables problem and, under conservative/limiting approximations, have reported analytical solutions for the attributes and variables sample sizes. Through computer simulation of this problem, we have calculated attributes and variables sample sizes as a function of falsification, measurement uncertainties, and required detection probability without using approximations. Using realistic assumptions for uncertainty parameters of measurement, the simulation results support the conclusions: (1) previously used conservative approximations can be expensive because they lead to larger sample sizes than needed; and (2) the optimal verification strategy, as well as the falsification strategy, are highly dependent on the underlying uncertainty parameters of the measurement instruments. 1 ref., 3 figs

  20. Optimization of sampling parameters for standardized exhaled breath sampling.

    Science.gov (United States)

    Doran, Sophie; Romano, Andrea; Hanna, George B

    2017-09-05

    The lack of standardization of breath sampling is a major contributing factor to the poor repeatability of results and hence represents a barrier to the adoption of breath tests in clinical practice. On-line and bag breath sampling have advantages but do not suit multicentre clinical studies whereas storage and robust transport are essential for the conduct of wide-scale studies. Several devices have been developed to control sampling parameters and to concentrate volatile organic compounds (VOCs) onto thermal desorption (TD) tubes and subsequently transport those tubes for laboratory analysis. We conducted three experiments to investigate (i) the fraction of breath sampled (whole vs. lower expiratory exhaled breath); (ii) breath sample volume (125, 250, 500 and 1000ml) and (iii) breath sample flow rate (400, 200, 100 and 50 ml/min). The target VOCs were acetone and potential volatile biomarkers for oesophago-gastric cancer belonging to the aldehyde, fatty acids and phenol chemical classes. We also examined the collection execution time and the impact of environmental contamination. The experiments showed that the use of exhaled breath-sampling devices requires the selection of optimum sampling parameters. The increase in sample volume has improved the levels of VOCs detected. However, the influence of the fraction of exhaled breath and the flow rate depends on the target VOCs measured. The concentration of potential volatile biomarkers for oesophago-gastric cancer was not significantly different between the whole and lower airway exhaled breath. While the recovery of phenols and acetone from TD tubes was lower when breath sampling was performed at a higher flow rate, other VOCs were not affected. A dedicated 'clean air supply' overcomes the contamination from ambient air, but the breath collection device itself can be a source of contaminants. In clinical studies using VOCs to diagnose gastro-oesophageal cancer, the optimum parameters are 500mls sample volume

  1. Optimal sampling designs for large-scale fishery sample surveys in Greece

    Directory of Open Access Journals (Sweden)

    G. BAZIGOS

    2007-12-01

    The paper deals with the optimization of the following three large scale sample surveys: biological sample survey of commercial landings (BSCL, experimental fishing sample survey (EFSS, and commercial landings and effort sample survey (CLES.

  2. Simultaneous beam sampling and aperture shape optimization for SPORT

    International Nuclear Information System (INIS)

    Zarepisheh, Masoud; Li, Ruijiang; Xing, Lei; Ye, Yinyu

    2015-01-01

    Purpose: Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. Results: A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and

  3. Simultaneous beam sampling and aperture shape optimization for SPORT

    Energy Technology Data Exchange (ETDEWEB)

    Zarepisheh, Masoud; Li, Ruijiang; Xing, Lei, E-mail: Lei@stanford.edu [Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States); Ye, Yinyu [Department of Management Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2015-02-15

    Purpose: Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. Results: A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and

  4. Simultaneous beam sampling and aperture shape optimization for SPORT.

    Science.gov (United States)

    Zarepisheh, Masoud; Li, Ruijiang; Ye, Yinyu; Xing, Lei

    2015-02-01

    Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and neck and a prostate case

  5. Sample preparation optimization in fecal metabolic profiling.

    Science.gov (United States)

    Deda, Olga; Chatziioannou, Anastasia Chrysovalantou; Fasoula, Stella; Palachanis, Dimitris; Raikos, Νicolaos; Theodoridis, Georgios A; Gika, Helen G

    2017-03-15

    Metabolomic analysis of feces can provide useful insight on the metabolic status, the health/disease state of the human/animal and the symbiosis with the gut microbiome. As a result, recently there is increased interest on the application of holistic analysis of feces for biomarker discovery. For metabolomics applications, the sample preparation process used prior to the analysis of fecal samples is of high importance, as it greatly affects the obtained metabolic profile, especially since feces, as matrix are diversifying in their physicochemical characteristics and molecular content. However there is still little information in the literature and lack of a universal approach on sample treatment for fecal metabolic profiling. The scope of the present work was to study the conditions for sample preparation of rat feces with the ultimate goal of the acquisition of comprehensive metabolic profiles either untargeted by NMR spectroscopy and GC-MS or targeted by HILIC-MS/MS. A fecal sample pooled from male and female Wistar rats was extracted under various conditions by modifying the pH value, the nature of the organic solvent and the sample weight to solvent volume ratio. It was found that the 1/2 (w f /v s ) ratio provided the highest number of metabolites under neutral and basic conditions in both untargeted profiling techniques. Concerning LC-MS profiles, neutral acetonitrile and propanol provided higher signals and wide metabolite coverage, though extraction efficiency is metabolite dependent. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Determining an optimal supply chain strategy

    Directory of Open Access Journals (Sweden)

    Intaher M. Ambe

    2012-11-01

    Full Text Available In today’s business environment, many companies want to become efficient and flexible, but have struggled, in part, because they have not been able to formulate optimal supply chain strategies. Often this is as a result of insufficient knowledge about the costs involved in maintaining supply chains and the impact of the supply chain on their operations. Hence, these companies find it difficult to manufacture at a competitive cost and respond quickly and reliably to market demand. Mismatched strategies are the root cause of the problems that plague supply chains, and supply-chain strategies based on a one-size-fits-all strategy often fail. The purpose of this article is to suggest instruments to determine an optimal supply chain strategy. This article, which is conceptual in nature, provides a review of current supply chain strategies and suggests a framework for determining an optimal strategy.

  7. Optimal relaxed causal sampler using sampled-date system theory

    NARCIS (Netherlands)

    Shekhawat, Hanumant; Meinsma, Gjerrit

    This paper studies the design of an optimal relaxed causal sampler using sampled data system theory. A lifted frequency domain approach is used to obtain the existence conditions and the optimal sampler. A state space formulation of the results is also provided. The resulting optimal relaxed causal

  8. Optimizing sampling approaches along ecological gradients

    DEFF Research Database (Denmark)

    Schweiger, Andreas; Irl, Severin D. H.; Steinbauer, Manuel

    2016-01-01

    1. Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying...... patterns in a statistically solid and reproducible manner, given the normal restrictions in labour, time and money. However, a technical guideline about an adequate sampling design to maximize prediction success under restricted resources is lacking. This study aims at developing such a solid...... and reproducible guideline for sampling along gradients in all fields of ecology and science in general. 2. We conducted simulations with artificial data for five common response types known in ecology, each represented by a simple function (no response, linear, exponential, symmetric unimodal and asymmetric...

  9. Study of phosphors determination in biological samples

    International Nuclear Information System (INIS)

    Oliveira, Rosangela Magda de.

    1994-01-01

    In this paper, phosphors determination by neutron activation analysis in milk and bone samples was studied employing both instrumental and radiochemical separation methods. The analysis with radiochemistry separation consisted of the simultaneous irradiation of the samples and standards during 30 minutes, dissolution of the samples, hold back carrier, addition precipitation of phosphorus with ammonium phosphomolibdate (A.M.P.) and phosphorus-32 by counting by using Geiger-Mueller detector. The instrumental analysis consisted of the simultaneous irradiation of the samples and standards during 30 minutes, transfer of the samples into a counting planchet and measurement of the beta radiation emitted by phosphorus-32, after a suitable decay period. After the phosphorus analysis methods were established they were applied to both commercial milk and animal bone samples, and data obtained in the instrumental and radiochemical separation methods for each sample, were compared between themselves. In this work, it became possible to obtain analysis methods for phosphorus that can be applied independently of the sample quantity available, and the phosphorus content in the samples or interference that can be present in them. (author). 51 refs., 7 figs., 4 tabs

  10. Optimal quantum sample complexity of learning algorithms

    NARCIS (Netherlands)

    Arunachalam, S.; de Wolf, R.

    2017-01-01

    In learning theory, the VC dimension of a concept class C is the most common way to measure its "richness." A fundamental result says that the number of examples needed to learn an unknown target concept c 2 C under an unknown distribution D, is tightly determined by the VC dimension d of the

  11. Rapid determination of actinides in seawater samples

    International Nuclear Information System (INIS)

    Maxwell, S.L.; Culligan, B.K.; Hutchison, J.B.; Utsey, R.C.; McAlister, D.R.

    2014-01-01

    A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti +3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1-2 weeks and provide chemical yields of ∼30-60 %. This new sample preparation method can be performed in 4-8 h with tracer yields of ∼85-95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort. (author)

  12. Neuro-genetic system for optimization of GMI samples sensitivity.

    Science.gov (United States)

    Pitta Botelho, A C O; Vellasco, M M B R; Hall Barbosa, C R; Costa Silva, E

    2016-03-01

    Magnetic sensors are largely used in several engineering areas. Among them, magnetic sensors based on the Giant Magnetoimpedance (GMI) effect are a new family of magnetic sensing devices that have a huge potential for applications involving measurements of ultra-weak magnetic fields. The sensitivity of magnetometers is directly associated with the sensitivity of their sensing elements. The GMI effect is characterized by a large variation of the impedance (magnitude and phase) of a ferromagnetic sample, when subjected to a magnetic field. Recent studies have shown that phase-based GMI magnetometers have the potential to increase the sensitivity by about 100 times. The sensitivity of GMI samples depends on several parameters, such as sample length, external magnetic field, DC level and frequency of the excitation current. However, this dependency is yet to be sufficiently well-modeled in quantitative terms. So, the search for the set of parameters that optimizes the samples sensitivity is usually empirical and very time consuming. This paper deals with this problem by proposing a new neuro-genetic system aimed at maximizing the impedance phase sensitivity of GMI samples. A Multi-Layer Perceptron (MLP) Neural Network is used to model the impedance phase and a Genetic Algorithm uses the information provided by the neural network to determine which set of parameters maximizes the impedance phase sensitivity. The results obtained with a data set composed of four different GMI sample lengths demonstrate that the neuro-genetic system is able to correctly and automatically determine the set of conditioning parameters responsible for maximizing their phase sensitivities. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. A proposal of optimal sampling design using a modularity strategy

    Science.gov (United States)

    Simone, A.; Giustolisi, O.; Laucelli, D. B.

    2016-08-01

    In real water distribution networks (WDNs) are present thousands nodes and optimal placement of pressure and flow observations is a relevant issue for different management tasks. The planning of pressure observations in terms of spatial distribution and number is named sampling design and it was faced considering model calibration. Nowadays, the design of system monitoring is a relevant issue for water utilities e.g., in order to manage background leakages, to detect anomalies and bursts, to guarantee service quality, etc. In recent years, the optimal location of flow observations related to design of optimal district metering areas (DMAs) and leakage management purposes has been faced considering optimal network segmentation and the modularity index using a multiobjective strategy. Optimal network segmentation is the basis to identify network modules by means of optimal conceptual cuts, which are the candidate locations of closed gates or flow meters creating the DMAs. Starting from the WDN-oriented modularity index, as a metric for WDN segmentation, this paper proposes a new way to perform the sampling design, i.e., the optimal location of pressure meters, using newly developed sampling-oriented modularity index. The strategy optimizes the pressure monitoring system mainly based on network topology and weights assigned to pipes according to the specific technical tasks. A multiobjective optimization minimizes the cost of pressure meters while maximizing the sampling-oriented modularity index. The methodology is presented and discussed using the Apulian and Exnet networks.

  14. Optimized Analytical Method to Determine Gallic and Picric Acids in Pyrotechnic Samples by Using HPLC/UV (Reverse Phase); Optimizacion del Metodo Analitico mediante HPLC/UV Operando en Fase Inversa para la Determinacion de Acido Galico y Acido Picrico en Muestras de Origen Pirotecnico

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Alonso, S.; Perez Pastor, R. M.

    2013-10-01

    A study on the optimization and development of a chromatographic method for the determination of gallic and picric acids in pyrotechnic samples is presented. In order to achieve this, both analytical conditions by HPLC with diode detection and extraction step of a selected sample were studied. (Author)

  15. Using remotely-sensed data for optimal field sampling

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2008-09-01

    Full Text Available M B E R 2 0 0 8 15 USING REMOTELY- SENSED DATA FOR OPTIMAL FIELD SAMPLING BY DR PRAVESH DEBBA STATISTICS IS THE SCIENCE pertaining to the collection, summary, analysis, interpretation and presentation of data. It is often impractical... studies are: where to sample, what to sample and how many samples to obtain. Conventional sampling techniques are not always suitable in environmental studies and scientists have explored the use of remotely-sensed data as ancillary information to aid...

  16. Determination of strontium-90 in soil samples

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C C

    1976-06-01

    The determination of /sup 90/Sr in soil by tri-n-butyl phosphate (TBP) is often interfered with iron which is always present in soil sample. Based on the method given by the U.S. Environmental Protection Agency, HClO/sub 4/ is added to remove iron ions while the soil sample is analyzed with TBP. The effect of different concentrations of HClO/sub 4/ on extraction yield of iron and chemical yield of yttrium is investigated. The experimental results show that 2N HClO/sub 4/ is the optimum concentration. The chemical yield of yttrium can reach about 60 percent, and all iron ions can be removed. This method has successfully been applied to analyze the soil samples taken from the site of the nuclear power plant in North Taiwan.

  17. Determination of radium-226 in environmental samples

    International Nuclear Information System (INIS)

    Powers, R.P.; Turnage, N.E.; Kanipe, L.G.

    1980-01-01

    The analysis of soil and water samples for 226 Ra by gamma spectrometry with a Ge(Li) detector was compared with that by radiochemical separation followed by 222 Rn de-emanation. Lower limits of detection (LLD) for 226 Ra were calculated for the two analytical techniques. The Ge(Li) system was found to have an LLD for soil comparable to that calculated for the de-emanation procedure, but the Ge(Li) system was found to have a significantly higher LLD for water samples. Cost analysis indicated that the cost of 222 Ra determination with a Ge(Li) system can be less than with the de-emanation procedure if the Ge(Li) system can perform at least one other isotopic anaysis per sample

  18. Sr-90 determination in aqueous and soils samples

    International Nuclear Information System (INIS)

    Gonzalez Sintas, Maria F.; Cerchietti, Maria L.; Arguelles, Maria G.

    2009-01-01

    The main objective of this paper is to evaluate the method for Sr-90 determination in aqueous sample and soils. Area and Personal Dosimetry laboratory (DPA) determines the presence of Sr-90 by Liquid Scintillation (LSC) by applying method of the double window and corresponding adjustments. Calibration is performed by standard solutions of 90 Sr/ 90 Y, where spectral 90 Sr and 90 Y zones are optimized. The initial treatment of the liquid samples includes the concentration for evaporation, while the solid ones dissolve for microwave and acidic digestion. The separation of the analyte involves a selective chromatographic extraction. An average efficiency for 90 Sr of 77 ± 1 % was obtained; the factor a/b was 0,85 ± 0,01 and recovery of 82 ± 8 %. The resultant MAD was 0,10 Bq/L in aqueous samples and 0,10 Bq/g in solid samples. (author)

  19. Optimal sampling schemes for vegetation and geological field visits

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2012-07-01

    Full Text Available The presentation made to Wits Statistics Department was on common classification methods used in the field of remote sensing, and the use of remote sensing to design optimal sampling schemes for field visits with applications in vegetation...

  20. Using remote sensing images to design optimal field sampling schemes

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2008-08-01

    Full Text Available sampling schemes case studies Optimized field sampling representing the overall distribution of a particular mineral Deriving optimal exploration target zones CONTINUUM REMOVAL for vegetation [13, 27, 46]. The convex hull transform is a method... of normalizing spectra [16, 41]. The convex hull technique is anal- ogous to fitting a rubber band over a spectrum to form a continuum. Figure 5 shows the concept of the convex hull transform. The differ- ence between the hull and the orig- inal spectrum...

  1. Determining the optimal number of individual samples to pool for quantification of average herd levels of antimicrobial resistance genes in Danish pig herds using high-throughput qPCR

    DEFF Research Database (Denmark)

    Clasen, Julie; Mellerup, Anders; Olsen, John Elmerdahl

    2016-01-01

    The primary objective of this study was to determine the minimum number of individual fecal samples to pool together in order to obtain a representative sample for herd level quantification of antimicrobial resistance (AMR) genes in a Danish pig herd, using a novel high-throughput qPCR assay...

  2. Sampling optimization for printer characterization by direct search.

    Science.gov (United States)

    Bianco, Simone; Schettini, Raimondo

    2012-12-01

    Printer characterization usually requires many printer inputs and corresponding color measurements of the printed outputs. In this brief, a sampling optimization for printer characterization on the basis of direct search is proposed to maintain high color accuracy with a reduction in the number of characterization samples required. The proposed method is able to match a given level of color accuracy requiring, on average, a characterization set cardinality which is almost one-fourth of that required by the uniform sampling, while the best method in the state of the art needs almost one-third. The number of characterization samples required can be further reduced if the proposed algorithm is coupled with a sequential optimization method that refines the sample values in the device-independent color space. The proposed sampling optimization method is extended to deal with multiple substrates simultaneously, giving statistically better colorimetric accuracy (at the α = 0.05 significance level) than sampling optimization techniques in the state of the art optimized for each individual substrate, thus allowing use of a single set of characterization samples for multiple substrates.

  3. Determination of radioactivity in meat samples

    International Nuclear Information System (INIS)

    Malik, G.M.; Atta, M.A.; Shafiq, M.; Zafar, M.S.

    1993-01-01

    The presence of radionuclides in edibles can create harmful effects in the human body. It is, therefore, essential that the radioactivity must be searched in the food stuff specially in those items which are available near the nuclear installations. The radioactivity in the meat samples obtained from the surroundings of PINSTECH (Pakistan Institute of Nuclear Science and Technology), PINSTECH Complex has been determined using high resolution Ge(Li) gamma ray spectrometer and a low level beta counting system. The results show that the measured values of the radioactivity are below the maximum permissible levels. (author)

  4. The determination of optimal climate policy

    International Nuclear Information System (INIS)

    Aaheim, Asbjoern

    2010-01-01

    Analyses of the costs and benefits of climate policy, such as the Stern Review, evaluate alternative strategies to reduce greenhouse gas emissions by requiring that the cost of emission cuts in each and every year has to be covered by the associated value of avoided damage, discounted by a an exogenously chosen rate. An alternative is to optimize abatement programmes towards a stationary state, where the concentrations of greenhouse gases are stabilized and shadow prices, including the rate of discount, are determined endogenously. This paper examines the properties of optimized stabilization. It turns out that the implications for the evaluation of climate policy are substantial if compared with evaluations of the present value of costs and benefits based on exogenously chosen shadow prices. Comparisons of discounted costs and benefits tend to exaggerate the importance of the choice of discount rate, while ignoring the importance of future abatement costs, which turns out to be essential for the optimal abatement path. Numerical examples suggest that early action may be more beneficial than indicated by comparisons of costs and benefits discounted by a rate chosen on the basis of current observations. (author)

  5. Localized Multiple Kernel Learning Via Sample-Wise Alternating Optimization.

    Science.gov (United States)

    Han, Yina; Yang, Kunde; Ma, Yuanliang; Liu, Guizhong

    2014-01-01

    Our objective is to train support vector machines (SVM)-based localized multiple kernel learning (LMKL), using the alternating optimization between the standard SVM solvers with the local combination of base kernels and the sample-specific kernel weights. The advantage of alternating optimization developed from the state-of-the-art MKL is the SVM-tied overall complexity and the simultaneous optimization on both the kernel weights and the classifier. Unfortunately, in LMKL, the sample-specific character makes the updating of kernel weights a difficult quadratic nonconvex problem. In this paper, starting from a new primal-dual equivalence, the canonical objective on which state-of-the-art methods are based is first decomposed into an ensemble of objectives corresponding to each sample, namely, sample-wise objectives. Then, the associated sample-wise alternating optimization method is conducted, in which the localized kernel weights can be independently obtained by solving their exclusive sample-wise objectives, either linear programming (for l1-norm) or with closed-form solutions (for lp-norm). At test time, the learnt kernel weights for the training data are deployed based on the nearest-neighbor rule. Hence, to guarantee their generality among the test part, we introduce the neighborhood information and incorporate it into the empirical loss when deriving the sample-wise objectives. Extensive experiments on four benchmark machine learning datasets and two real-world computer vision datasets demonstrate the effectiveness and efficiency of the proposed algorithm.

  6. Determination of platinum in biological samples by NAA

    International Nuclear Information System (INIS)

    Okada, Yukiko; Hirai, Shoji; Sakurai, Hiromu; Haraguchi, Hiroki.

    1990-01-01

    Recently, a Pt compound, Cisplatin (cis-dichlorodiamine platinum) has been used therapeutically as an effective anti-malignant-cancer drug. However, since this drug has a harmful aftereffect on kidney, an urgent study of how to reduce its toxicity without influencing the therapeutic effect is needed. We have to understand the behavior of Pt in biological organs in order to elucidate the mechanism of its toxicity reduction. In this study, the analytical conditions for the determination of Pt in biological samples by neutron activation analysis, such as cooling time, counting time and sample weight, are optimized. Freeze-dried samples of the liver, kidney and whole blood of a rat treated with Cisplatin were prepared to evaluate the precision of the analysis and the lower limit of determination. 199 Au (t 1/2 = 3.15 d) produced from 199 Pt (n, γ, β - ) was selected as the analytical radionuclide. A concentration of ca. 1 ppm Pt was determinable under the optimal conditions: a cooling time of 5 d and a counting time of 1 h. Pt in the respective organs of the control rat was not detected under the same analytical conditions. The concentrations of Pt in the liver, kidney, spleen, pancreas and lung of a rat treated with both Cisplatin and sodium selenite were higher than those of a rat treated only with Cisplatin. (author)

  7. Monte Carlo importance sampling optimization for system reliability applications

    International Nuclear Information System (INIS)

    Campioni, Luca; Vestrucci, Paolo

    2004-01-01

    This paper focuses on the reliability analysis of multicomponent systems by the importance sampling technique, and, in particular, it tackles the optimization aspect. A methodology based on the minimization of the variance at the component level is proposed for the class of systems consisting of independent components. The claim is that, by means of such a methodology, the optimal biasing could be achieved without resorting to the typical approach by trials

  8. Determination of I-131 in milk samples

    International Nuclear Information System (INIS)

    Fernandez G, I.; Rodriguez C, G.; Quevedo A, J. L.

    1996-01-01

    In our country, in the near future, an isotope center will be in operation, and due to its characteristics, it is possible the discharge of radionuclides to the atmosphere during its normal exploitation, as well as in case of accident. Considering the kind and the concentration of the radioactive material released to the atmosphere, the possible ways of contamination were determined, playing the milk the most significant role, because the Iodine-131 is in the radionuclide inventory of this center, being possible to pass to the food-chain soil-grass-milk, due to the fact that the center is located in a cattle zone. Owing to these facts, it is necessary to rely on a method for determining Iodine-131 that allows to control its presence in milk samples, when the isotope center start to operate. The direct absorption of Iodine-131 in an anionic exchange resin and the subsequent analysis of this resin for gamma spectrometry with a Nal (Tl) detector is a cheap, simple and fast method with a recovery average greater than the 95%. (authors). 5 refs., 3 tabs

  9. Determination of the Prosumer's Optimal Bids

    Science.gov (United States)

    Ferruzzi, Gabriella; Rossi, Federico; Russo, Angela

    2015-12-01

    This paper considers a microgrid connected with a medium-voltage (MV) distribution network. It is assumed that the microgrid, which is managed by a prosumer, operates in a competitive environment and participates in the day-ahead market. Then, as the first step of the short-term management problem, the prosumer must determine the bids to be submitted to the market. The offer strategy is based on the application of an optimization model, which is solved for different hourly price profiles of energy exchanged with the main grid. The proposed procedure is applied to a microgrid and four different its configurations were analyzed. The configurations consider the presence of thermoelectric units that only produce electricity, a boiler or/and cogeneration power plants for the thermal loads, and an electric storage system. The numerical results confirmed the numerous theoretical considerations that have been made.

  10. spsann - optimization of sample patterns using spatial simulated annealing

    Science.gov (United States)

    Samuel-Rosa, Alessandro; Heuvelink, Gerard; Vasques, Gustavo; Anjos, Lúcia

    2015-04-01

    There are many algorithms and computer programs to optimize sample patterns, some private and others publicly available. A few have only been presented in scientific articles and text books. This dispersion and somewhat poor availability is holds back to their wider adoption and further development. We introduce spsann, a new R-package for the optimization of sample patterns using spatial simulated annealing. R is the most popular environment for data processing and analysis. Spatial simulated annealing is a well known method with widespread use to solve optimization problems in the soil and geo-sciences. This is mainly due to its robustness against local optima and easiness of implementation. spsann offers many optimizing criteria for sampling for variogram estimation (number of points or point-pairs per lag distance class - PPL), trend estimation (association/correlation and marginal distribution of the covariates - ACDC), and spatial interpolation (mean squared shortest distance - MSSD). spsann also includes the mean or maximum universal kriging variance (MUKV) as an optimizing criterion, which is used when the model of spatial variation is known. PPL, ACDC and MSSD were combined (PAN) for sampling when we are ignorant about the model of spatial variation. spsann solves this multi-objective optimization problem scaling the objective function values using their maximum absolute value or the mean value computed over 1000 random samples. Scaled values are aggregated using the weighted sum method. A graphical display allows to follow how the sample pattern is being perturbed during the optimization, as well as the evolution of its energy state. It is possible to start perturbing many points and exponentially reduce the number of perturbed points. The maximum perturbation distance reduces linearly with the number of iterations. The acceptance probability also reduces exponentially with the number of iterations. R is memory hungry and spatial simulated annealing is a

  11. Optimization of protein samples for NMR using thermal shift assays

    International Nuclear Information System (INIS)

    Kozak, Sandra; Lercher, Lukas; Karanth, Megha N.; Meijers, Rob; Carlomagno, Teresa; Boivin, Stephane

    2016-01-01

    Maintaining a stable fold for recombinant proteins is challenging, especially when working with highly purified and concentrated samples at temperatures >20 °C. Therefore, it is worthwhile to screen for different buffer components that can stabilize protein samples. Thermal shift assays or ThermoFluor"® provide a high-throughput screening method to assess the thermal stability of a sample under several conditions simultaneously. Here, we describe a thermal shift assay that is designed to optimize conditions for nuclear magnetic resonance studies, which typically require stable samples at high concentration and ambient (or higher) temperature. We demonstrate that for two challenging proteins, the multicomponent screen helped to identify ingredients that increased protein stability, leading to clear improvements in the quality of the spectra. Thermal shift assays provide an economic and time-efficient method to find optimal conditions for NMR structural studies.

  12. Optimization of protein samples for NMR using thermal shift assays

    Energy Technology Data Exchange (ETDEWEB)

    Kozak, Sandra [European Molecular Biology Laboratory (EMBL), Hamburg Outstation, SPC Facility (Germany); Lercher, Lukas; Karanth, Megha N. [European Molecular Biology Laboratory (EMBL), SCB Unit (Germany); Meijers, Rob [European Molecular Biology Laboratory (EMBL), Hamburg Outstation, SPC Facility (Germany); Carlomagno, Teresa, E-mail: teresa.carlomagno@oci.uni-hannover.de [European Molecular Biology Laboratory (EMBL), SCB Unit (Germany); Boivin, Stephane, E-mail: sboivin77@hotmail.com, E-mail: s.boivin@embl-hamburg.de [European Molecular Biology Laboratory (EMBL), Hamburg Outstation, SPC Facility (Germany)

    2016-04-15

    Maintaining a stable fold for recombinant proteins is challenging, especially when working with highly purified and concentrated samples at temperatures >20 °C. Therefore, it is worthwhile to screen for different buffer components that can stabilize protein samples. Thermal shift assays or ThermoFluor{sup ®} provide a high-throughput screening method to assess the thermal stability of a sample under several conditions simultaneously. Here, we describe a thermal shift assay that is designed to optimize conditions for nuclear magnetic resonance studies, which typically require stable samples at high concentration and ambient (or higher) temperature. We demonstrate that for two challenging proteins, the multicomponent screen helped to identify ingredients that increased protein stability, leading to clear improvements in the quality of the spectra. Thermal shift assays provide an economic and time-efficient method to find optimal conditions for NMR structural studies.

  13. On Optimal, Minimal BRDF Sampling for Reflectance Acquisition

    DEFF Research Database (Denmark)

    Nielsen, Jannik Boll; Jensen, Henrik Wann; Ramamoorthi, Ravi

    2015-01-01

    The bidirectional reflectance distribution function (BRDF) is critical for rendering, and accurate material representation requires data-driven reflectance models. However, isotropic BRDFs are 3D functions, and measuring the reflectance of a flat sample can require a million incident and outgoing...... direction pairs, making the use of measured BRDFs impractical. In this paper, we address the problem of reconstructing a measured BRDF from a limited number of samples. We present a novel mapping of the BRDF space, allowing for extraction of descriptive principal components from measured databases......, such as the MERL BRDF database. We optimize for the best sampling directions, and explicitly provide the optimal set of incident and outgoing directions in the Rusinkiewicz parameterization for n = {1, 2, 5, 10, 20} samples. Based on the principal components, we describe a method for accurately reconstructing BRDF...

  14. Optimal updating magnitude in adaptive flat-distribution sampling.

    Science.gov (United States)

    Zhang, Cheng; Drake, Justin A; Ma, Jianpeng; Pettitt, B Montgomery

    2017-11-07

    We present a study on the optimization of the updating magnitude for a class of free energy methods based on flat-distribution sampling, including the Wang-Landau (WL) algorithm and metadynamics. These methods rely on adaptive construction of a bias potential that offsets the potential of mean force by histogram-based updates. The convergence of the bias potential can be improved by decreasing the updating magnitude with an optimal schedule. We show that while the asymptotically optimal schedule for the single-bin updating scheme (commonly used in the WL algorithm) is given by the known inverse-time formula, that for the Gaussian updating scheme (commonly used in metadynamics) is often more complex. We further show that the single-bin updating scheme is optimal for very long simulations, and it can be generalized to a class of bandpass updating schemes that are similarly optimal. These bandpass updating schemes target only a few long-range distribution modes and their optimal schedule is also given by the inverse-time formula. Constructed from orthogonal polynomials, the bandpass updating schemes generalize the WL and Langfeld-Lucini-Rago algorithms as an automatic parameter tuning scheme for umbrella sampling.

  15. Optimizing Soil Moisture Sampling Locations for Validation Networks for SMAP

    Science.gov (United States)

    Roshani, E.; Berg, A. A.; Lindsay, J.

    2013-12-01

    Soil Moisture Active Passive satellite (SMAP) is scheduled for launch on Oct 2014. Global efforts are underway for establishment of soil moisture monitoring networks for both the pre- and post-launch validation and calibration of the SMAP products. In 2012 the SMAP Validation Experiment, SMAPVEX12, took place near Carman Manitoba, Canada where nearly 60 fields were sampled continuously over a 6 week period for soil moisture and several other parameters simultaneous to remotely sensed images of the sampling region. The locations of these sampling sites were mainly selected on the basis of accessibility, soil texture, and vegetation cover. Although these criteria are necessary to consider during sampling site selection, they do not guarantee optimal site placement to provide the most efficient representation of the studied area. In this analysis a method for optimization of sampling locations is presented which combines the state-of-art multi-objective optimization engine (non-dominated sorting genetic algorithm, NSGA-II), with the kriging interpolation technique to minimize the number of sampling sites while simultaneously minimizing the differences between the soil moisture map resulted from the kriging interpolation and soil moisture map from radar imaging. The algorithm is implemented in Whitebox Geospatial Analysis Tools, which is a multi-platform open-source GIS. The optimization framework is subject to the following three constraints:. A) sampling sites should be accessible to the crew on the ground, B) the number of sites located in a specific soil texture should be greater than or equal to a minimum value, and finally C) the number of sampling sites with a specific vegetation cover should be greater than or equal to a minimum constraint. The first constraint is implemented into the proposed model to keep the practicality of the approach. The second and third constraints are considered to guarantee that the collected samples from each soil texture categories

  16. Optimizing incomplete sample designs for item response model parameters

    NARCIS (Netherlands)

    van der Linden, Willem J.

    Several models for optimizing incomplete sample designs with respect to information on the item parameters are presented. The following cases are considered: (1) known ability parameters; (2) unknown ability parameters; (3) item sets with multiple ability scales; and (4) response models with

  17. Optimized preparation of urine samples for two-dimensional electrophoresis and initial application to patient samples

    DEFF Research Database (Denmark)

    Lafitte, Daniel; Dussol, Bertrand; Andersen, Søren

    2002-01-01

    OBJECTIVE: We optimized of the preparation of urinary samples to obtain a comprehensive map of urinary proteins of healthy subjects and then compared this map with the ones obtained with patient samples to show that the pattern was specific of their kidney disease. DESIGN AND METHODS: The urinary...

  18. Energy group structure determination using particle swarm optimization

    International Nuclear Information System (INIS)

    Yi, Ce; Sjoden, Glenn

    2013-01-01

    Highlights: ► Particle swarm optimization is applied to determine broad group structure. ► A graph representation of the broad group structure problem is introduced. ► The approach is tested on a fuel-pin model. - Abstract: Multi-group theory is widely applied for the energy domain discretization when solving the Linear Boltzmann Equation. To reduce the computational cost, fine group cross libraries are often down-sampled into broad group cross section libraries. Cross section data collapsing generally involves two steps: Firstly, the broad group structure has to be determined; secondly, a weighting scheme is used to evaluate the broad cross section library based on the fine group cross section data and the broad group structure. A common scheme is to average the fine group cross section weighted by the fine group flux. Cross section collapsing techniques have been intensively researched. However, most studies use a pre-determined group structure, open based on experience, to divide the neutron energy spectrum into thermal, epi-thermal, fast, etc. energy range. In this paper, a swarm intelligence algorithm, particle swarm optimization (PSO), is applied to optimize the broad group structure. A graph representation of the broad group structure determination problem is introduced. And the swarm intelligence algorithm is used to solve the graph model. The effectiveness of the approach is demonstrated using a fuel-pin model

  19. Ad-Hoc vs. Standardized and Optimized Arthropod Diversity Sampling

    Directory of Open Access Journals (Sweden)

    Pedro Cardoso

    2009-09-01

    Full Text Available The use of standardized and optimized protocols has been recently advocated for different arthropod taxa instead of ad-hoc sampling or sampling with protocols defined on a case-by-case basis. We present a comparison of both sampling approaches applied for spiders in a natural area of Portugal. Tests were made to their efficiency, over-collection of common species, singletons proportions, species abundance distributions, average specimen size, average taxonomic distinctness and behavior of richness estimators. The standardized protocol revealed three main advantages: (1 higher efficiency; (2 more reliable estimations of true richness; and (3 meaningful comparisons between undersampled areas.

  20. Enhancing sampling design in mist-net bat surveys by accounting for sample size optimization

    OpenAIRE

    Trevelin, Leonardo Carreira; Novaes, Roberto Leonan Morim; Colas-Rosas, Paul François; Benathar, Thayse Cristhina Melo; Peres, Carlos A.

    2017-01-01

    The advantages of mist-netting, the main technique used in Neotropical bat community studies to date, include logistical implementation, standardization and sampling representativeness. Nonetheless, study designs still have to deal with issues of detectability related to how different species behave and use the environment. Yet there is considerable sampling heterogeneity across available studies in the literature. Here, we approach the problem of sample size optimization. We evaluated the co...

  1. Fluoroquinolone antibiotics in environmental waters: sample preparation and determination.

    Science.gov (United States)

    Speltini, Andrea; Sturini, Michela; Maraschi, Federica; Profumo, Antonella

    2010-04-01

    The aim of this review is to provide a general overview on the analytical methods proposed in the last decade for trace fluoroquinolone (FQ) determination in environmental waters. A large number of studies have been developed on this topic in reason of the importance of their monitoring in the studies of environmental mobility and potential degradation pathways. Every step of the analysis has been carefully considered, with a particular attention to sample preparation, in relationship with the problems involved in the analysis of real matrices. The different strategies to minimise interference from organic matter and to achieve optimal sensitivity, especially important in those samples with lower FQ concentrations, were also highlighted. Results and progress in this field have been described and critically commented. Moreover, a worldwide overview on the presence of FQs in the environmental waters has been reported.

  2. Determination of Phthalates in Drinking Water Samples

    African Journals Online (AJOL)

    user

    successfully applied to the analysis of phthalate esters contamination in bottled drinking water samples. ... esters are used in the manufacturing of polyvinyl chloride. (PVC). ... water, soil, air, food products and the human body. (Castillo et al.

  3. Determination of copper in powdered chocolate samples by slurry-sampling flame atomic-absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Walter N.L. dos; Silva, Erik G.P. da; Fernandes, Marcelo S.; Araujo, Rennan G.O.; Costa, Anto' ' enio C.S.; Ferreira, Sergio L.C. [Nucleo de Excelencia em Quimica Analitica da Bahia, Universidade Federal da Bahia, Instituto de Quimica, Salvador, Bahia (Brazil); Vale, M.G.R. [Instituto de Quimica, Universidade Federal da Bahia do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul (Brazil)

    2005-06-01

    Chocolate is a complex sample with a high content of organic compounds and its analysis generally involves digestion procedures that might include the risk of losses and/or contamination. The determination of copper in chocolate is important because copper compounds are extensively used as fungicides in the farming of cocoa. In this paper, a slurry-sampling flame atomic-absorption spectrometric method is proposed for determination of copper in powdered chocolate samples. Optimization was carried out using univariate methodology involving the variables nature and concentration of the acid solution for slurry preparation, sonication time, and sample mass. The recommended conditions include a sample mass of 0.2 g, 2.0 mol L{sup -1} hydrochloric acid solution, and a sonication time of 15 min. The calibration curve was prepared using aqueous copper standards in 2.0 mol L{sup -1} hydrochloric acid. This method allowed determination of copper in chocolate with a detection limit of 0.4 {mu}g g{sup -1} and precision, expressed as relative standard deviation (RSD), of 2.5% (n=10) for a copper content of approximately 30 {mu}g g{sup -1}, using a chocolate mass of 0.2 g. The accuracy was confirmed by analyzing the certified reference materials NIST SRM 1568a rice flour and NIES CRM 10-b rice flour. The proposed method was used for determination of copper in three powdered chocolate samples, the copper content of which varied between 26.6 and 31.5 {mu}g g{sup -1}. The results showed no significant differences with those obtained after complete digestion, using a t-test for comparison. (orig.)

  4. Classifier-Guided Sampling for Complex Energy System Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Backlund, Peter B. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Eddy, John P. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    This report documents the results of a Laboratory Directed Research and Development (LDRD) effort enti tled "Classifier - Guided Sampling for Complex Energy System Optimization" that was conducted during FY 2014 and FY 2015. The goal of this proj ect was to develop, implement, and test major improvements to the classifier - guided sampling (CGS) algorithm. CGS is type of evolutionary algorithm for perform ing search and optimization over a set of discrete design variables in the face of one or more objective functions. E xisting evolutionary algorithms, such as genetic algorithms , may require a large number of o bjecti ve function evaluations to identify optimal or near - optimal solutions . Reducing the number of evaluations can result in significant time savings, especially if the objective function is computationally expensive. CGS reduce s the evaluation count by us ing a Bayesian network classifier to filter out non - promising candidate designs , prior to evaluation, based on their posterior probabilit ies . In this project, b oth the single - objective and multi - objective version s of the CGS are developed and tested on a set of benchm ark problems. As a domain - specific case study, CGS is used to design a microgrid for use in islanded mode during an extended bulk power grid outage.

  5. Sample size optimization in nuclear material control. 1

    International Nuclear Information System (INIS)

    Gladitz, J.

    1982-01-01

    Equations have been derived and exemplified which allow the determination of the minimum variables sample size for given false alarm and detection probabilities of nuclear material losses and diversions, respectively. (author)

  6. OPTIMAL METHOD FOR PREPARATION OF SILICATE ROCK SAMPLES FOR ANALYTICAL PURPOSES

    Directory of Open Access Journals (Sweden)

    Maja Vrkljan

    2004-12-01

    Full Text Available The purpose of this study was to determine an optimal dissolution method for silicate rock samples for further analytical purposes. Analytical FAAS method of determining cobalt, chromium, copper, nickel, lead and zinc content in gabbro sample and geochemical standard AGV-1 has been applied for verification. Dissolution in mixtures of various inorganic acids has been tested, as well as Na2CO3 fusion technique. The results obtained by different methods have been compared and dissolution in the mixture of HNO3 + HF has been recommended as optimal.

  7. Gravimetric determination of uranium in SALE samples

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    As a participant in the Safeguards Analytical Laboratory Evaluation (SALE) program, the Analytical Chemistry Laboratory at General Atomic routinely assays uranium dioxide and uranyl nitrate SALE samples for uranium content. Gravimetric methods are relatively easy and inexpensive to apply when the samples for uranium content. Gravimetric methods are relatively easy and inexpensive to apply when the samples are free from substantial amounts of metallic impurities. Clearly the gravimetric procedure alone is not specific for uranium and must be enhanced by the use of impurity corrections. Emission spectrography is used routinely as the technique of choice for making such corrections. In cases where it is essential to assay specifically for uranium, the modified Davies-Gray titration using a weighed titrant method is applied. In this paper some essential features of these gravimetric and titrimetric procedures are discussed

  8. Optimal Path Determination for Flying Vehicle to Search an Object

    Science.gov (United States)

    Heru Tjahjana, R.; Heri Soelistyo U, R.; Ratnasari, L.; Irawanto, B.

    2018-01-01

    In this paper, a method to determine optimal path for flying vehicle to search an object is proposed. Background of the paper is controlling air vehicle to search an object. Optimal path determination is one of the most popular problem in optimization. This paper describe model of control design for a flying vehicle to search an object, and focus on the optimal path that used to search an object. In this paper, optimal control model is used to control flying vehicle to make the vehicle move in optimal path. If the vehicle move in optimal path, then the path to reach the searched object also optimal. The cost Functional is one of the most important things in optimal control design, in this paper the cost functional make the air vehicle can move as soon as possible to reach the object. The axis reference of flying vehicle uses N-E-D (North-East-Down) coordinate system. The result of this paper are the theorems which say that the cost functional make the control optimal and make the vehicle move in optimal path are proved analytically. The other result of this paper also shows the cost functional which used is convex. The convexity of the cost functional is use for guarantee the existence of optimal control. This paper also expose some simulations to show an optimal path for flying vehicle to search an object. The optimization method which used to find the optimal control and optimal path vehicle in this paper is Pontryagin Minimum Principle.

  9. Sequential determination of important ecotoxic radionuclides in nuclear waste samples

    International Nuclear Information System (INIS)

    Bilohuscin, J.

    2016-01-01

    In the dissertation thesis we focused on the development and optimization of a sequential determination method for radionuclides 93 Zr, 94 Nb, 99 Tc and 126 Sn, employing extraction chromatography sorbents TEVA (R) Resin and Anion Exchange Resin, supplied by Eichrom Industries. Prior to the attestation of sequential separation of these proposed radionuclides from radioactive waste samples, a unique sequential procedure of 90 Sr, 239 Pu, 241 Am separation from urine matrices was tried, using molecular recognition sorbents of AnaLig (R) series and extraction chromatography sorbent DGA (R) Resin. On these experiments, four various sorbents were continually used for separation, including PreFilter Resin sorbent, which removes interfering organic materials present in raw urine. After the acquisition of positive results of this sequential procedure followed experiments with a 126 Sn separation using TEVA (R) Resin and Anion Exchange Resin sorbents. Radiochemical recoveries obtained from samples of radioactive evaporate concentrates and sludge showed high efficiency of the separation, while values of 126 Sn were under the minimum detectable activities MDA. Activity of 126 Sn was determined after ingrowth of daughter nuclide 126m Sb on HPGe gamma detector, with minimal contamination of gamma interfering radionuclides with decontamination factors (D f ) higher then 1400 for 60 Co and 47000 for 137 Cs. Based on the acquired experiments and results of these separation procedures, a complex method of sequential separation of 93 Zr, 94 Nb, 99 Tc and 126 Sn was proposed, which included optimization steps similar to those used in previous parts of the dissertation work. Application of the sequential separation method for sorbents TEVA (R) Resin and Anion Exchange Resin on real samples of radioactive wastes provided satisfactory results and an economical, time sparing, efficient method. (author)

  10. Spectroscopic determination of optimal hydration time of zircon surface

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Garcia R, G. [Instituto Tecnologico de Toluca, Division de Estudios del Posgrado, Av. Tecnologico s/n, Ex-Rancho La Virgen, 52140 Metepec, Estado de Mexico (Mexico); Garcia G, N., E-mail: eduardo.ordonez@inin.gob.m [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Av. Colon y Av. Tollocan, 50180 Toluca, Estado de Mexico (Mexico)

    2010-07-01

    When a mineral surface is immersed in an aqueous solution, it develops and electric charge produced by the amphoteric dissociation of hydroxyl groups created by the hydration of the solid surface. This is one influential surface property. The complete hydration process takes a time which is specific for each mineral species. The knowledge of the aqueous solution contact time for complete surface hydration is mandatory for further surface phenomena studies. This study deals with the optimal hydration time of the raw zircon (ZrSiO{sub 4}) surface comparing the classical potentiometric titrations with a fluorescence spectroscopy technique. The latter is easy and rea liable as it demands only one sample batch to determine the optimal time to ensure a total hydration of the zircon surface. The analytical results of neutron activation analysis showed the presence of trace quantities of Dy{sup 3+}, Eu{sup 3+} and Er{sup 3} in the bulk of zircon. The Dy{sup 3+} is structured in the zircon crystalline lattice and undergoes the same chemical reactions as zircon. Furthermore, the Dy{sup 3+} has a good fluorescent response whose intensity is enhanced by hydration molecules. The results show that, according to the potentiometric analysis, the hydration process for each batch (at least 8 sample batches) takes around 2 h, while the spectrometric method indicates only 5 minutes from only one batch. Both methods showed that the zircon surface have a 16 h optimal hydration time. (Author)

  11. Spectroscopic determination of optimal hydration time of zircon surface

    International Nuclear Information System (INIS)

    Ordonez R, E.; Garcia R, G.; Garcia G, N.

    2010-01-01

    When a mineral surface is immersed in an aqueous solution, it develops and electric charge produced by the amphoteric dissociation of hydroxyl groups created by the hydration of the solid surface. This is one influential surface property. The complete hydration process takes a time which is specific for each mineral species. The knowledge of the aqueous solution contact time for complete surface hydration is mandatory for further surface phenomena studies. This study deals with the optimal hydration time of the raw zircon (ZrSiO 4 ) surface comparing the classical potentiometric titrations with a fluorescence spectroscopy technique. The latter is easy and rea liable as it demands only one sample batch to determine the optimal time to ensure a total hydration of the zircon surface. The analytical results of neutron activation analysis showed the presence of trace quantities of Dy 3+ , Eu 3+ and Er 3 in the bulk of zircon. The Dy 3+ is structured in the zircon crystalline lattice and undergoes the same chemical reactions as zircon. Furthermore, the Dy 3+ has a good fluorescent response whose intensity is enhanced by hydration molecules. The results show that, according to the potentiometric analysis, the hydration process for each batch (at least 8 sample batches) takes around 2 h, while the spectrometric method indicates only 5 minutes from only one batch. Both methods showed that the zircon surface have a 16 h optimal hydration time. (Author)

  12. Triangular Geometrized Sampling Heuristics for Fast Optimal Motion Planning

    Directory of Open Access Journals (Sweden)

    Ahmed Hussain Qureshi

    2015-02-01

    Full Text Available Rapidly-exploring Random Tree (RRT-based algorithms have become increasingly popular due to their lower computational complexity as compared with other path planning algorithms. The recently presented RRT* motion planning algorithm improves upon the original RRT algorithm by providing optimal path solutions. While RRT determines an initial collision-free path fairly quickly, RRT* guarantees almost certain convergence to an optimal, obstacle-free path from the start to the goal points for any given geometrical environment. However, the main limitations of RRT* include its slow processing rate and high memory consumption, due to the large number of iterations required for calculating the optimal path. In order to overcome these limitations, we present another improvement, i.e, the Triangular Geometerized-RRT* (TG-RRT* algorithm, which utilizes triangular geometrical methods to improve the performance of the RRT* algorithm in terms of the processing time and a decreased number of iterations required for an optimal path solution. Simulations comparing the performance results of the improved TG-RRT* with RRT* are presented to demonstrate the overall improvement in performance and optimal path detection.

  13. The determination of uranium in pyrite samples

    International Nuclear Information System (INIS)

    Jacobs, J.J.

    1979-01-01

    An existing method for the determination of uranium in rocks and minerals is examined for the determination of uranium in materials containing pyrite. The results are comparable with those obtained by a spectrophotometric method, the precision (relative standard deviation) of the method for standards with U 3 O 8 contents of 1500 and 300 p.p.m. being 0,03 and 0,08 respectively when prepared in pyrite, and 0,15 and 0,06 respectively when made up with inert diluent. Full details of the procedure are given in accompanying appendices [af

  14. Rate-distortion optimization for compressive video sampling

    Science.gov (United States)

    Liu, Ying; Vijayanagar, Krishna R.; Kim, Joohee

    2014-05-01

    The recently introduced compressed sensing (CS) framework enables low complexity video acquisition via sub- Nyquist rate sampling. In practice, the resulting CS samples are quantized and indexed by finitely many bits (bit-depth) for transmission. In applications where the bit-budget for video transmission is constrained, rate- distortion optimization (RDO) is essential for quality video reconstruction. In this work, we develop a double-level RDO scheme for compressive video sampling, where frame-level RDO is performed by adaptively allocating the fixed bit-budget per frame to each video block based on block-sparsity, and block-level RDO is performed by modelling the block reconstruction peak-signal-to-noise ratio (PSNR) as a quadratic function of quantization bit-depth. The optimal bit-depth and the number of CS samples are then obtained by setting the first derivative of the function to zero. In the experimental studies the model parameters are initialized with a small set of training data, which are then updated with local information in the model testing stage. Simulation results presented herein show that the proposed double-level RDO significantly enhances the reconstruction quality for a bit-budget constrained CS video transmission system.

  15. Spectrophotometric determination of chromium in geological samples

    International Nuclear Information System (INIS)

    Rathore, D.P.S.; Tarafder, P.K.

    1992-01-01

    A method for the determination of chromium is presented, based on the oxidation of hydroxylamine hydrochloride to nitrous acid by chromium(VI) in acetic acid medium followed by diazotization of the nitrite produced with p-aminophenylmercaptoacetic acid and subsequent coupling of the diazonium salt with N-(1-naphthyl)ethylenediamine di-hydrochloride in acidic medium to form a stable blueish azo dye. The method is suitable for the determination of chromium(VI) from 0.04 to 1.2 mg l -1 in a 1.0-cm cuvette. The molar absorptivity and Sandell's sensitivity are 3.65x10 4 l mol -1 cm -1 and 0.0014μg cm -2 , respectively. (author). 17 refs.; 3 figs

  16. Comparison between dispersive solid-phase and dispersive liquid-liquid microextraction combined with spectrophotometric determination of malachite green in water samples based on ultrasound-assisted and preconcentration under multi-variable experimental design optimization.

    Science.gov (United States)

    Alipanahpour Dil, Ebrahim; Ghaedi, Mehrorang; Asfaram, Arash; Zare, Fahimeh; Mehrabi, Fatemeh; Sadeghfar, Fardin

    2017-11-01

    The ultrasound-assisted dispersive solid-phase microextraction (USA-DSPME) and the ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) developed for as an ultra preconcentration and/or technique for the determination of malachite green (MG) in water samples. Central composite design based on analysis of variance and desirability function guide finding best operational conditions and represent dependency of response to variables viz. volume of extraction, eluent and disperser solvent, pH, adsorbent mass and ultrasonication time has significant influence on methods efficiency. Optimum conditions was set for USA-DSPME as: 1mg CNTs/Zn:ZnO@Ni 2 P-NCs; 4min sonication time and 130μL eluent at pH 6.0. Meanwhile optimum point for USA-DLLME conditions were fixed at pH 6.0; 4min sonication time and 130, 650μL and 10mL of extraction solvent (CHCl 3 ), disperser solvent (ethanol) and sample volume, respectively. Under the above specified best operational conditions, the enrichment factors for the USA-DSPME and USA-DLLME were 88.89 and 147.30, respectively. The methods has linear response in the range of 20.0 to 4000.0ngmL -1 with the correlation coefficients (r) between 0.9980 to 0.9995, while its reasonable detection limits viz. 1.386 to 2.348ngmL -1 and good relative standard deviations varied from 1.1% to 2.8% (n=10) candidate this method for successful monitoring of analyte from various media. The relative recoveries of the MG dye from water samples at spiking level of 500ngmL -1 were in the range between 94.50% and 98.86%. The proposed methods has been successfully applied to the analysis of the MG dye in water samples, and a satisfactory result was obtained. Copyright © 2017. Published by Elsevier B.V.

  17. Optimization of the sampling scheme for maps of physical and chemical properties estimated by kriging

    Directory of Open Access Journals (Sweden)

    Gener Tadeu Pereira

    2013-10-01

    Full Text Available The sampling scheme is essential in the investigation of the spatial variability of soil properties in Soil Science studies. The high costs of sampling schemes optimized with additional sampling points for each physical and chemical soil property, prevent their use in precision agriculture. The purpose of this study was to obtain an optimal sampling scheme for physical and chemical property sets and investigate its effect on the quality of soil sampling. Soil was sampled on a 42-ha area, with 206 geo-referenced points arranged in a regular grid spaced 50 m from each other, in a depth range of 0.00-0.20 m. In order to obtain an optimal sampling scheme for every physical and chemical property, a sample grid, a medium-scale variogram and the extended Spatial Simulated Annealing (SSA method were used to minimize kriging variance. The optimization procedure was validated by constructing maps of relative improvement comparing the sample configuration before and after the process. A greater concentration of recommended points in specific areas (NW-SE direction was observed, which also reflects a greater estimate variance at these locations. The addition of optimal samples, for specific regions, increased the accuracy up to 2 % for chemical and 1 % for physical properties. The use of a sample grid and medium-scale variogram, as previous information for the conception of additional sampling schemes, was very promising to determine the locations of these additional points for all physical and chemical soil properties, enhancing the accuracy of kriging estimates of the physical-chemical properties.

  18. Determination of 40K in water samples

    International Nuclear Information System (INIS)

    Delgado, C. E.; Miranda C, L.; Cuevas J, A. K.; Vega C, H. R.

    2014-10-01

    The natural water used for human consumption comes from different sources, which may contain suspended solids in varying proportions. In groundwater, the source of suspended solids is related to the dissolution of mineral strata by the waters and leaching of rocks. Also, the radioactivity could concentrate on the bodies of slow-moving water that eventually could present a risk to ecosystems, as well as for the consumer. The water usually contains several natural radionuclides as: tritium, radon, radio, uranium isotopes, etc. The objective of this study was to evaluate the concentration of 40 K in water from different areas of Zacatecas state (Mexico). Four water samples were taken in triplicate from different areas; the 40 K concentration was measured with a spectrum metric system of gamma radiation with NaI (Tl) scintillation detector of 7.62 cm. In the measuring process a standard was prepared using water and KCl analytic grade where the 40 K concentration is 6.25 mol/Lt adding 250 mg/ml of potassium. Also the system was calibrated in energy using 3 point sources of 137 Cs, diameter 22 Na and 7.62 cm of height, using containers Marinelli and 60 Co. In the obtained spectra was observed that the photon of 1.432 MeV that emits the 40 K when decaying is the most important. The highest concentration was of 123 ± 5.2 Bq/lt and the lowest was of 9 ± 0.4 Bq/lt. Under the standards of drinking water, an amount of 40 K deposits an effective dose which contributes to annual dose received by people. (Author)

  19. Fluorescent determination of graphene quantum dots in water samples

    Energy Technology Data Exchange (ETDEWEB)

    Benítez-Martínez, Sandra; Valcárcel, Miguel, E-mail: qa1meobj@uco.es

    2015-10-08

    This work presents a simple, fast and sensitive method for the preconcentration and quantification of graphene quantum dots (GQDs) in aqueous samples. GQDs are considered an object of analysis (analyte) not an analytical tool which is the most frequent situation in Analytical Nanoscience and Nanotechnology. This approach is based on the preconcentration of graphene quantum dots on an anion exchange sorbent by solid phase extraction and their subsequent elution prior fluorimetric analysis of the solution containing graphene quantum dots. Parameters of the extraction procedure such as sample volume, type of solvent, sample pH, sample flow rate and elution conditions were investigated in order to achieve extraction efficiency. The limits of detection and quantification were 7.5 μg L{sup −1} and 25 μg L{sup −1}, respectively. The precision for 200 μg L{sup −1}, expressed as %RSD, was 2.8%. Recoveries percentages between 86.9 and 103.9% were obtained for two different concentration levels. Interferences from other nanoparticles were studied and no significant changes were observed at the concentration levels tested. Consequently, the optimized procedure has great potential to be applied to the determination of graphene quantum dots at trace levels in drinking and environmental waters. - Highlights: • Development of a novel and simple method for determination of graphene quantum dots. • Preconcentration of graphene quantum dots by solid phase extraction. • Fluorescence spectroscopy allows fast measurements. • High sensitivity and great reproducibility are achieved.

  20. Robust Estimation of Diffusion-Optimized Ensembles for Enhanced Sampling

    DEFF Research Database (Denmark)

    Tian, Pengfei; Jónsson, Sigurdur Æ.; Ferkinghoff-Borg, Jesper

    2014-01-01

    The multicanonical, or flat-histogram, method is a common technique to improve the sampling efficiency of molecular simulations. The idea is that free-energy barriers in a simulation can be removed by simulating from a distribution where all values of a reaction coordinate are equally likely......, and subsequently reweight the obtained statistics to recover the Boltzmann distribution at the temperature of interest. While this method has been successful in practice, the choice of a flat distribution is not necessarily optimal. Recently, it was proposed that additional performance gains could be obtained...

  1. Searching for the Optimal Sampling Solution: Variation in Invertebrate Communities, Sample Condition and DNA Quality.

    Directory of Open Access Journals (Sweden)

    Martin M Gossner

    Full Text Available There is a great demand for standardising biodiversity assessments in order to allow optimal comparison across research groups. For invertebrates, pitfall or flight-interception traps are commonly used, but sampling solution differs widely between studies, which could influence the communities collected and affect sample processing (morphological or genetic. We assessed arthropod communities with flight-interception traps using three commonly used sampling solutions across two forest types and two vertical strata. We first considered the effect of sampling solution and its interaction with forest type, vertical stratum, and position of sampling jar at the trap on sample condition and community composition. We found that samples collected in copper sulphate were more mouldy and fragmented relative to other solutions which might impair morphological identification, but condition depended on forest type, trap type and the position of the jar. Community composition, based on order-level identification, did not differ across sampling solutions and only varied with forest type and vertical stratum. Species richness and species-level community composition, however, differed greatly among sampling solutions. Renner solution was highly attractant for beetles and repellent for true bugs. Secondly, we tested whether sampling solution affects subsequent molecular analyses and found that DNA barcoding success was species-specific. Samples from copper sulphate produced the fewest successful DNA sequences for genetic identification, and since DNA yield or quality was not particularly reduced in these samples additional interactions between the solution and DNA must also be occurring. Our results show that the choice of sampling solution should be an important consideration in biodiversity studies. Due to the potential bias towards or against certain species by Ethanol-containing sampling solution we suggest ethylene glycol as a suitable sampling solution when

  2. A Method for Determining Optimal Residential Energy Efficiency Packages

    Energy Technology Data Exchange (ETDEWEB)

    Polly, B. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gestwick, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bianchi, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Anderson, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Horowitz, S. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Christensen, C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Judkoff, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2011-04-01

    This report describes an analysis method for determining optimal residential energy efficiency retrofit packages and, as an illustrative example, applies the analysis method to a 1960s-era home in eight U.S. cities covering a range of International Energy Conservation Code (IECC) climate regions. The method uses an optimization scheme that considers average energy use (determined from building energy simulations) and equivalent annual cost to recommend optimal retrofit packages specific to the building, occupants, and location.

  3. Optimal CCD readout by digital correlated double sampling

    Science.gov (United States)

    Alessandri, C.; Abusleme, A.; Guzman, D.; Passalacqua, I.; Alvarez-Fontecilla, E.; Guarini, M.

    2016-01-01

    Digital correlated double sampling (DCDS), a readout technique for charge-coupled devices (CCD), is gaining popularity in astronomical applications. By using an oversampling ADC and a digital filter, a DCDS system can achieve a better performance than traditional analogue readout techniques at the expense of a more complex system analysis. Several attempts to analyse and optimize a DCDS system have been reported, but most of the work presented in the literature has been experimental. Some approximate analytical tools have been presented for independent parameters of the system, but the overall performance and trade-offs have not been yet modelled. Furthermore, there is disagreement among experimental results that cannot be explained by the analytical tools available. In this work, a theoretical analysis of a generic DCDS readout system is presented, including key aspects such as the signal conditioning stage, the ADC resolution, the sampling frequency and the digital filter implementation. By using a time-domain noise model, the effect of the digital filter is properly modelled as a discrete-time process, thus avoiding the imprecision of continuous-time approximations that have been used so far. As a result, an accurate, closed-form expression for the signal-to-noise ratio at the output of the readout system is reached. This expression can be easily optimized in order to meet a set of specifications for a given CCD, thus providing a systematic design methodology for an optimal readout system. Simulated results are presented to validate the theory, obtained with both time- and frequency-domain noise generation models for completeness.

  4. A framework for determining optimal petroleum leasing

    International Nuclear Information System (INIS)

    Robinson, D.R.

    1991-01-01

    The techniques of auction theory and option theory are combined to allow valuation under both geologic and oil price uncertainty. The primary motivation for developing this framework is to understand the prevalence of leasing in transferring ownership of oil properties. Under a standard oil lease, the landowner sells an oil company the right to explore and develop a tract of land for a fixed period of time. If oil is found, a fraction of the revenues is reserved for the landowner. Compared to the outright sale of the minerals, leasing has the disadvantages of: (1) lowering total oil field value through alteration of investment incentives; (2) providing the seller with a more risk cash flow; and (3) increasing legal and administrative costs. It is demonstrated here that in lease sales as compared to full mineral interest sales, the relative disadvantages are offset by more effective value transfer to the seller. For the base-case parameters, the optimal lease in a bonus auction gives the seller 28% more value than the sale of the full mineral interest. There is a loss in the leasing process from distortion of development timing incentives

  5. Sample sizes to control error estimates in determining soil bulk density in California forest soils

    Science.gov (United States)

    Youzhi Han; Jianwei Zhang; Kim G. Mattson; Weidong Zhang; Thomas A. Weber

    2016-01-01

    Characterizing forest soil properties with high variability is challenging, sometimes requiring large numbers of soil samples. Soil bulk density is a standard variable needed along with element concentrations to calculate nutrient pools. This study aimed to determine the optimal sample size, the number of observation (n), for predicting the soil bulk density with a...

  6. Effect of sample preparation methods on photometric determination of the tellurium and cobalt content in the samples of copper concentrates

    Directory of Open Access Journals (Sweden)

    Viktoriya Butenko

    2016-03-01

    Full Text Available Methods of determination of cobalt and nickel in copper concentrates currently used in factory laboratories are very labor intensive and time consuming. The limiting stage of the analysis is preliminary chemical sample preparation. Carrying out the decomposition process of industrial samples with concentrated mineral acids in open systems does not allow to improve the metrological characteristics of the methods, for this reason improvement the methods of sample preparation is quite relevant and has a practical interest. The work was dedicated to the determination of the optimal conditions of preliminary chemical preparation of copper concentrate samples for the subsequent determination of cobalt and tellurium in the obtained solution using tellurium-spectrophotometric method. Decomposition of the samples was carried out by acid dissolving in individual mineral acids and their mixtures by heating in an open system as well as by using ultrasonification and microwave radiation in a closed system. In order to select the optimal conditions for the decomposition of the samples in a closed system the phase contact time and ultrasonic generator’s power were varied. Intensification of the processes of decomposition of copper concentrates with nitric acid (1:1, ultrasound and microwave radiation allowed to transfer quantitatively cobalt and tellurium into solution spending 20 and 30 min respectively. This reduced the amount of reactants used and improved the accuracy of determination by running the process in strictly identical conditions.

  7. A general method to determine sampling windows for nonlinear mixed effects models with an application to population pharmacokinetic studies.

    Science.gov (United States)

    Foo, Lee Kien; McGree, James; Duffull, Stephen

    2012-01-01

    Optimal design methods have been proposed to determine the best sampling times when sparse blood sampling is required in clinical pharmacokinetic studies. However, the optimal blood sampling time points may not be feasible in clinical practice. Sampling windows, a time interval for blood sample collection, have been proposed to provide flexibility in blood sampling times while preserving efficient parameter estimation. Because of the complexity of the population pharmacokinetic models, which are generally nonlinear mixed effects models, there is no analytical solution available to determine sampling windows. We propose a method for determination of sampling windows based on MCMC sampling techniques. The proposed method attains a stationary distribution rapidly and provides time-sensitive windows around the optimal design points. The proposed method is applicable to determine sampling windows for any nonlinear mixed effects model although our work focuses on an application to population pharmacokinetic models. Copyright © 2012 John Wiley & Sons, Ltd.

  8. Otimização dos parâmetros de extração para determinação multiresíduo de pesticidas em amostras de água empregando microextração em fase sólida Parameter optimization for pesticide multiresidue determination using SPME in water samples

    Directory of Open Access Journals (Sweden)

    Emy Komatsu

    2004-10-01

    Full Text Available In this study the factors that affect the extraction of pesticide residues from water samples for their determination by solid-phase micro-extraction (SPME and GC/MS were optimized. The fiber polymer, the extraction mode, the ionic strength, the stirring rate, the pH and the extraction time were the most significant parameters evaluated. The recovery obtained with the proposed method ranged from 94 to 110% and the sensitivity of the method, determined by calculating the detection limit (DL, ranged from 0.004 to 0.1 mug l-1. The results obtained with spiked real samples, at the 0.1 mug l-1 level, showed acceptable conformity with the expected values.

  9. Optimizing UV Index determination from broadband irradiances

    Science.gov (United States)

    Tereszchuk, Keith A.; Rochon, Yves J.; McLinden, Chris A.; Vaillancourt, Paul A.

    2018-03-01

    A study was undertaken to improve upon the prognosticative capability of Environment and Climate Change Canada's (ECCC) UV Index forecast model. An aspect of that work, and the topic of this communication, was to investigate the use of the four UV broadband surface irradiance fields generated by ECCC's Global Environmental Multiscale (GEM) numerical prediction model to determine the UV Index. The basis of the investigation involves the creation of a suite of routines which employ high-spectral-resolution radiative transfer code developed to calculate UV Index fields from GEM forecasts. These routines employ a modified version of the Cloud-J v7.4 radiative transfer model, which integrates GEM output to produce high-spectral-resolution surface irradiance fields. The output generated using the high-resolution radiative transfer code served to verify and calibrate GEM broadband surface irradiances under clear-sky conditions and their use in providing the UV Index. A subsequent comparison of irradiances and UV Index under cloudy conditions was also performed. Linear correlation agreement of surface irradiances from the two models for each of the two higher UV bands covering 310.70-330.0 and 330.03-400.00 nm is typically greater than 95 % for clear-sky conditions with associated root-mean-square relative errors of 6.4 and 4.0 %. However, underestimations of clear-sky GEM irradiances were found on the order of ˜ 30-50 % for the 294.12-310.70 nm band and by a factor of ˜ 30 for the 280.11-294.12 nm band. This underestimation can be significant for UV Index determination but would not impact weather forecasting. Corresponding empirical adjustments were applied to the broadband irradiances now giving a correlation coefficient of unity. From these, a least-squares fitting was derived for the calculation of the UV Index. The resultant differences in UV indices from the high-spectral-resolution irradiances and the resultant GEM broadband irradiances are typically within 0

  10. Overconfidence, Managerial Optimism, and the Determinants of Capital Structure

    Directory of Open Access Journals (Sweden)

    Alexandre di Miceli da Silveira

    2008-12-01

    Full Text Available This research examines the determinants of the capital structure of firms introducing a behavioral perspective that has received little attention in corporate finance literature. The following central hypothesis emerges from a set of recently developed theories: firms managed by optimistic and/or overconfident people will choose more levered financing structures than others, ceteris paribus. We propose different proxies for optimism/overconfidence, based on the manager’s status as an entrepreneur or non-entrepreneur, an idea that is supported by theories and solid empirical evidence, as well as on the pattern of ownership of the firm’s shares by its manager. The study also includes potential determinants of capital structure used in earlier research. We use a sample of Brazilian firms listed in the Sao Paulo Stock Exchange (Bovespa in the years 1998 to 2003. The empirical analysis suggests that the proxies for the referred cognitive biases are important determinants of capital structure. We also found as relevant explanatory variables: profitability, size, dividend payment and tangibility, as well as some indicators that capture the firms’ corporate governance standards. These results suggest that behavioral approaches based on human psychology research can offer relevant contributions to the understanding of corporate decision making.

  11. Optimal sample size for probability of detection curves

    International Nuclear Information System (INIS)

    Annis, Charles; Gandossi, Luca; Martin, Oliver

    2013-01-01

    Highlights: • We investigate sample size requirement to develop probability of detection curves. • We develop simulations to determine effective inspection target sizes, number and distribution. • We summarize these findings and provide guidelines for the NDE practitioner. -- Abstract: The use of probability of detection curves to quantify the reliability of non-destructive examination (NDE) systems is common in the aeronautical industry, but relatively less so in the nuclear industry, at least in European countries. Due to the nature of the components being inspected, sample sizes tend to be much lower. This makes the manufacturing of test pieces with representative flaws, in sufficient numbers, so to draw statistical conclusions on the reliability of the NDT system under investigation, quite costly. The European Network for Inspection and Qualification (ENIQ) has developed an inspection qualification methodology, referred to as the ENIQ Methodology. It has become widely used in many European countries and provides assurance on the reliability of NDE systems, but only qualitatively. The need to quantify the output of inspection qualification has become more important as structural reliability modelling and quantitative risk-informed in-service inspection methodologies become more widely used. A measure of the NDE reliability is necessary to quantify risk reduction after inspection and probability of detection (POD) curves provide such a metric. The Joint Research Centre, Petten, The Netherlands supported ENIQ by investigating the question of the sample size required to determine a reliable POD curve. As mentioned earlier manufacturing of test pieces with defects that are typically found in nuclear power plants (NPPs) is usually quite expensive. Thus there is a tendency to reduce sample sizes, which in turn increases the uncertainty associated with the resulting POD curve. The main question in conjunction with POS curves is the appropriate sample size. Not

  12. Optimal Sample Size for Probability of Detection Curves

    International Nuclear Information System (INIS)

    Annis, Charles; Gandossi, Luca; Martin, Oliver

    2012-01-01

    The use of Probability of Detection (POD) curves to quantify NDT reliability is common in the aeronautical industry, but relatively less so in the nuclear industry. The European Network for Inspection Qualification's (ENIQ) Inspection Qualification Methodology is based on the concept of Technical Justification, a document assembling all the evidence to assure that the NDT system in focus is indeed capable of finding the flaws for which it was designed. This methodology has become widely used in many countries, but the assurance it provides is usually of qualitative nature. The need to quantify the output of inspection qualification has become more important, especially as structural reliability modelling and quantitative risk-informed in-service inspection methodologies become more widely used. To credit the inspections in structural reliability evaluations, a measure of the NDT reliability is necessary. A POD curve provides such metric. In 2010 ENIQ developed a technical report on POD curves, reviewing the statistical models used to quantify inspection reliability. Further work was subsequently carried out to investigate the issue of optimal sample size for deriving a POD curve, so that adequate guidance could be given to the practitioners of inspection reliability. Manufacturing of test pieces with cracks that are representative of real defects found in nuclear power plants (NPP) can be very expensive. Thus there is a tendency to reduce sample sizes and in turn reduce the conservatism associated with the POD curve derived. Not much guidance on the correct sample size can be found in the published literature, where often qualitative statements are given with no further justification. The aim of this paper is to summarise the findings of such work. (author)

  13. Optimal sampling plan for clean development mechanism energy efficiency lighting projects

    International Nuclear Information System (INIS)

    Ye, Xianming; Xia, Xiaohua; Zhang, Jiangfeng

    2013-01-01

    Highlights: • A metering cost minimisation model is built to assist the sampling plan for CDM projects. • The model minimises the total metering cost by the determination of optimal sample size. • The required 90/10 criterion sampling accuracy is maintained. • The proposed metering cost minimisation model is applicable to other CDM projects as well. - Abstract: Clean development mechanism (CDM) project developers are always interested in achieving required measurement accuracies with the least metering cost. In this paper, a metering cost minimisation model is proposed for the sampling plan of a specific CDM energy efficiency lighting project. The problem arises from the particular CDM sampling requirement of 90% confidence and 10% precision for the small-scale CDM energy efficiency projects, which is known as the 90/10 criterion. The 90/10 criterion can be met through solving the metering cost minimisation problem. All the lights in the project are classified into different groups according to uncertainties of the lighting energy consumption, which are characterised by their statistical coefficient of variance (CV). Samples from each group are randomly selected to install power meters. These meters include less expensive ones with less functionality and more expensive ones with greater functionality. The metering cost minimisation model will minimise the total metering cost through the determination of the optimal sample size at each group. The 90/10 criterion is formulated as constraints to the metering cost objective. The optimal solution to the minimisation problem will therefore minimise the metering cost whilst meeting the 90/10 criterion, and this is verified by a case study. Relationships between the optimal metering cost and the population sizes of the groups, CV values and the meter equipment cost are further explored in three simulations. The metering cost minimisation model proposed for lighting systems is applicable to other CDM projects as

  14. Optimization conditions of samples saponification for tocopherol analysis.

    Science.gov (United States)

    Souza, Aloisio Henrique Pereira; Gohara, Aline Kirie; Rodrigues, Ângela Claudia; Ströher, Gisely Luzia; Silva, Danielle Cristina; Visentainer, Jesuí Vergílio; Souza, Nilson Evelázio; Matsushita, Makoto

    2014-09-01

    A full factorial design 2(2) (two factors at two levels) with duplicates was performed to investigate the influence of the factors agitation time (2 and 4 h) and the percentage of KOH (60% and 80% w/v) in the saponification of samples for the determination of α, β and γ+δ-tocopherols. The study used samples of peanuts (cultivar armadillo), produced and marketed in Maringá, PR. The factors % KOH and agitation time were significant, and an increase in their values contributed negatively to the responses. The interaction effect was not significant for the response δ-tocopherol, and the contribution of this effect to the other responses was positive, but less than 10%. The ANOVA and response surfaces analysis showed that the most efficient saponification procedure was obtained using a 60% (w/v) solution of KOH and with an agitation time of 2 h. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Determination of plutonium in air and smear samples

    International Nuclear Information System (INIS)

    Hinton, E.R. Jr.; Tucker, W.O.

    1981-01-01

    A method has been developed for the determination of plutonium in air samples and smear samples that were collected on filter papers. The sample papers are digested in nitric acid, extracted into 2-thenoyltrifluoroacetone (TTA)-xylene, and evaporated onto stainless steel disks. Alpha spectrometry is employed to determine the activity of each plutonium isotope. Each sample is spiked with plutonium-236. All glassware used in the procedure is disposable. The detection limits are 3 and 5 dpm (disintegrations per minute) for air and smear samples, respectively, with an average recovery of 87%

  16. Multiple sensitive estimation and optimal sample size allocation in the item sum technique.

    Science.gov (United States)

    Perri, Pier Francesco; Rueda García, María Del Mar; Cobo Rodríguez, Beatriz

    2018-01-01

    For surveys of sensitive issues in life sciences, statistical procedures can be used to reduce nonresponse and social desirability response bias. Both of these phenomena provoke nonsampling errors that are difficult to deal with and can seriously flaw the validity of the analyses. The item sum technique (IST) is a very recent indirect questioning method derived from the item count technique that seeks to procure more reliable responses on quantitative items than direct questioning while preserving respondents' anonymity. This article addresses two important questions concerning the IST: (i) its implementation when two or more sensitive variables are investigated and efficient estimates of their unknown population means are required; (ii) the determination of the optimal sample size to achieve minimum variance estimates. These aspects are of great relevance for survey practitioners engaged in sensitive research and, to the best of our knowledge, were not studied so far. In this article, theoretical results for multiple estimation and optimal allocation are obtained under a generic sampling design and then particularized to simple random sampling and stratified sampling designs. Theoretical considerations are integrated with a number of simulation studies based on data from two real surveys and conducted to ascertain the efficiency gain derived from optimal allocation in different situations. One of the surveys concerns cannabis consumption among university students. Our findings highlight some methodological advances that can be obtained in life sciences IST surveys when optimal allocation is achieved. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Statistical surrogate model based sampling criterion for stochastic global optimization of problems with constraints

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Su Gil; Jang, Jun Yong; Kim, Ji Hoon; Lee, Tae Hee [Hanyang University, Seoul (Korea, Republic of); Lee, Min Uk [Romax Technology Ltd., Seoul (Korea, Republic of); Choi, Jong Su; Hong, Sup [Korea Research Institute of Ships and Ocean Engineering, Daejeon (Korea, Republic of)

    2015-04-15

    Sequential surrogate model-based global optimization algorithms, such as super-EGO, have been developed to increase the efficiency of commonly used global optimization technique as well as to ensure the accuracy of optimization. However, earlier studies have drawbacks because there are three phases in the optimization loop and empirical parameters. We propose a united sampling criterion to simplify the algorithm and to achieve the global optimum of problems with constraints without any empirical parameters. It is able to select the points located in a feasible region with high model uncertainty as well as the points along the boundary of constraint at the lowest objective value. The mean squared error determines which criterion is more dominant among the infill sampling criterion and boundary sampling criterion. Also, the method guarantees the accuracy of the surrogate model because the sample points are not located within extremely small regions like super-EGO. The performance of the proposed method, such as the solvability of a problem, convergence properties, and efficiency, are validated through nonlinear numerical examples with disconnected feasible regions.

  18. Simultaneous determination of plutonium and uranium in environmental samples

    International Nuclear Information System (INIS)

    Jiao Shufen

    1993-01-01

    Plutonium and uranium in a plant sample ash was simultaneously determined by using anion exchange resin columns, and concentrated hydrochloric acid and nitric acid. At the final stage of the determination of the nuclides, each of them was electrodeposited together with a little amount of molybdenum carrier onto a stainless steel plate and measured by α-ray spectrometer. The recoveries of uranium and plutonium from the plant samples determined by adding internal standard 236 Pu which was 100% and 63%, respectively

  19. SamplingStrata: An R Package for the Optimization of Strati?ed Sampling

    Directory of Open Access Journals (Sweden)

    Giulio Barcaroli

    2014-11-01

    Full Text Available When designing a sampling survey, usually constraints are set on the desired precision levels regarding one or more target estimates (the Ys. If a sampling frame is available, containing auxiliary information related to each unit (the Xs, it is possible to adopt a stratified sample design. For any given strati?cation of the frame, in the multivariate case it is possible to solve the problem of the best allocation of units in strata, by minimizing a cost function sub ject to precision constraints (or, conversely, by maximizing the precision of the estimates under a given budget. The problem is to determine the best stratification in the frame, i.e., the one that ensures the overall minimal cost of the sample necessary to satisfy precision constraints. The Xs can be categorical or continuous; continuous ones can be transformed into categorical ones. The most detailed strati?cation is given by the Cartesian product of the Xs (the atomic strata. A way to determine the best stratification is to explore exhaustively the set of all possible partitions derivable by the set of atomic strata, evaluating each one by calculating the corresponding cost in terms of the sample required to satisfy precision constraints. This is una?ordable in practical situations, where the dimension of the space of the partitions can be very high. Another possible way is to explore the space of partitions with an algorithm that is particularly suitable in such situations: the genetic algorithm. The R package SamplingStrata, based on the use of a genetic algorithm, allows to determine the best strati?cation for a population frame, i.e., the one that ensures the minimum sample cost necessary to satisfy precision constraints, in a multivariate and multi-domain case.

  20. Martian Radiative Transfer Modeling Using the Optimal Spectral Sampling Method

    Science.gov (United States)

    Eluszkiewicz, J.; Cady-Pereira, K.; Uymin, G.; Moncet, J.-L.

    2005-01-01

    The large volume of existing and planned infrared observations of Mars have prompted the development of a new martian radiative transfer model that could be used in the retrievals of atmospheric and surface properties. The model is based on the Optimal Spectral Sampling (OSS) method [1]. The method is a fast and accurate monochromatic technique applicable to a wide range of remote sensing platforms (from microwave to UV) and was originally developed for the real-time processing of infrared and microwave data acquired by instruments aboard the satellites forming part of the next-generation global weather satellite system NPOESS (National Polarorbiting Operational Satellite System) [2]. As part of our on-going research related to the radiative properties of the martian polar caps, we have begun the development of a martian OSS model with the goal of using it to perform self-consistent atmospheric corrections necessary to retrieve caps emissivity from the Thermal Emission Spectrometer (TES) spectra. While the caps will provide the initial focus area for applying the new model, it is hoped that the model will be of interest to the wider Mars remote sensing community.

  1. Time optimization of 90Sr measurements: Sequential measurement of multiple samples during ingrowth of 90Y

    International Nuclear Information System (INIS)

    Holmgren, Stina; Tovedal, Annika; Björnham, Oscar; Ramebäck, Henrik

    2016-01-01

    The aim of this paper is to contribute to a more rapid determination of a series of samples containing 90 Sr by making the Cherenkov measurement of the daughter nuclide 90 Y more time efficient. There are many instances when an optimization of the measurement method might be favorable, such as; situations requiring rapid results in order to make urgent decisions or, on the other hand, to maximize the throughput of samples in a limited available time span. In order to minimize the total analysis time, a mathematical model was developed which calculates the time of ingrowth as well as individual measurement times for n samples in a series. This work is focused on the measurement of 90 Y during ingrowth, after an initial chemical separation of strontium, in which it is assumed that no other radioactive strontium isotopes are present. By using a fixed minimum detectable activity (MDA) and iterating the measurement time for each consecutive sample the total analysis time will be less, compared to using the same measurement time for all samples. It was found that by optimization, the total analysis time for 10 samples can be decreased greatly, from 21 h to 6.5 h, when assuming a MDA of 1 Bq/L and at a background count rate of approximately 0.8 cpm. - Highlights: • An approach roughly a factor of three more efficient than an un-optimized method. • The optimization gives a more efficient use of instrument time. • The efficiency increase ranges from a factor of three to 10, for 10 to 40 samples.

  2. Method for Determining Optimal Residential Energy Efficiency Retrofit Packages

    Energy Technology Data Exchange (ETDEWEB)

    Polly, B.; Gestwick, M.; Bianchi, M.; Anderson, R.; Horowitz, S.; Christensen, C.; Judkoff, R.

    2011-04-01

    Businesses, government agencies, consumers, policy makers, and utilities currently have limited access to occupant-, building-, and location-specific recommendations for optimal energy retrofit packages, as defined by estimated costs and energy savings. This report describes an analysis method for determining optimal residential energy efficiency retrofit packages and, as an illustrative example, applies the analysis method to a 1960s-era home in eight U.S. cities covering a range of International Energy Conservation Code (IECC) climate regions. The method uses an optimization scheme that considers average energy use (determined from building energy simulations) and equivalent annual cost to recommend optimal retrofit packages specific to the building, occupants, and location. Energy savings and incremental costs are calculated relative to a minimum upgrade reference scenario, which accounts for efficiency upgrades that would occur in the absence of a retrofit because of equipment wear-out and replacement with current minimum standards.

  3. Sample Size Determination for One- and Two-Sample Trimmed Mean Tests

    Science.gov (United States)

    Luh, Wei-Ming; Olejnik, Stephen; Guo, Jiin-Huarng

    2008-01-01

    Formulas to determine the necessary sample sizes for parametric tests of group comparisons are available from several sources and appropriate when population distributions are normal. However, in the context of nonnormal population distributions, researchers recommend Yuen's trimmed mean test, but formulas to determine sample sizes have not been…

  4. AAS determination of total mercury content in environmental samples

    International Nuclear Information System (INIS)

    Moskalova, M.; Zemberyova, M.

    1997-01-01

    Two methods for determination of total mercury content in environmental samples soils, and sediments, were compared. Dissolution procedure of soils, sediments, and biological material under elevated pressure followed by determination of mercury by cold vapour atomic absorption spectrometry using a MHS-1 system and direct total mercury determination without any chemical pretreatment from soil samples using a Trace Mercury Analyzer TMA-254 were compared. TMA-254 was also applied for the determination of mercury in various further standard reference materials. Good agreement with certified values of environmental reference materials was obtained. (authors)

  5. Spectrophotometric Determination of Boron in Environmental Water Samples

    International Nuclear Information System (INIS)

    San San; Khin Win Kyi; Kwaw Naing

    2002-02-01

    The present paper deals with the study on the methods for the determination of boron in the environmental water samples. The standard methods which are useful for this determination are discussed thoroughly in this work. Among the standard methods approved by American Public Health Association, the carmine method was selected for this study. Prior to the determination of boron in the water samples, the precision and accuracy of the methods of choice were examined by using standard boron solutions. The determination of Boron was carried out by using water samples, waste water from Aquaculture Research Centre, University of Yangon, the Ayeyarwady River water near Magway Myathalon Pagoda in Magway Division, ground water from Sanchaung Township, and tap water from Universities' Research Centre, University of Yangon. Analyses of these water samples were done and statistical treatment of the results was carried out. (author)

  6. Optimal sample to tracer ratio for isotope dilution mass spectrometry: the polyisotopic case

    International Nuclear Information System (INIS)

    Laszlo, G.; Ridder, P. de; Goldman, A.; Cappis, J.; Bievre, P. de

    1991-01-01

    The Isotope Dilution Mass Spectrometry (IDMS) measurement technique provides a means for determining the unknown amount of various isotopes of an element in a sample solution of known mass. The sample solution is mixed with an auxiliary solution, or tracer, containing a known amount of the same element having the same isotopes but of different relative abundances or isotopic composition and the induced change in the isotopic composition measured by isotope mass spectrometry. The technique involves the measurement of the abundance ratio of each isotope to a (same) reference isotope in the sample solution, in the tracer solution and in the blend of the sample and tracer solution. These isotope ratio measurements, the known element amount in the tracer and the known mass of sample solution are used to calculate the unknown amount of one isotope in the sample solution. Subsequently the unknown amount of element is determined. The purpose of this paper is to examine the optimization of the ratio of the estimated unknown amount of element in the sample solution to the known amount of element in the tracer solution in order to minimize the relative uncertainty in the determination of the unknown amount of element

  7. Sample size determination in clinical trials with multiple endpoints

    CERN Document Server

    Sozu, Takashi; Hamasaki, Toshimitsu; Evans, Scott R

    2015-01-01

    This book integrates recent methodological developments for calculating the sample size and power in trials with more than one endpoint considered as multiple primary or co-primary, offering an important reference work for statisticians working in this area. The determination of sample size and the evaluation of power are fundamental and critical elements in the design of clinical trials. If the sample size is too small, important effects may go unnoticed; if the sample size is too large, it represents a waste of resources and unethically puts more participants at risk than necessary. Recently many clinical trials have been designed with more than one endpoint considered as multiple primary or co-primary, creating a need for new approaches to the design and analysis of these clinical trials. The book focuses on the evaluation of power and sample size determination when comparing the effects of two interventions in superiority clinical trials with multiple endpoints. Methods for sample size calculation in clin...

  8. Neuromuscular dose-response studies: determining sample size.

    Science.gov (United States)

    Kopman, A F; Lien, C A; Naguib, M

    2011-02-01

    Investigators planning dose-response studies of neuromuscular blockers have rarely used a priori power analysis to determine the minimal sample size their protocols require. Institutional Review Boards and peer-reviewed journals now generally ask for this information. This study outlines a proposed method for meeting these requirements. The slopes of the dose-response relationships of eight neuromuscular blocking agents were determined using regression analysis. These values were substituted for γ in the Hill equation. When this is done, the coefficient of variation (COV) around the mean value of the ED₅₀ for each drug is easily calculated. Using these values, we performed an a priori one-sample two-tailed t-test of the means to determine the required sample size when the allowable error in the ED₅₀ was varied from ±10-20%. The COV averaged 22% (range 15-27%). We used a COV value of 25% in determining the sample size. If the allowable error in finding the mean ED₅₀ is ±15%, a sample size of 24 is needed to achieve a power of 80%. Increasing 'accuracy' beyond this point requires increasing greater sample sizes (e.g. an 'n' of 37 for a ±12% error). On the basis of the results of this retrospective analysis, a total sample size of not less than 24 subjects should be adequate for determining a neuromuscular blocking drug's clinical potency with a reasonable degree of assurance.

  9. Determination of atmospheric nitrogen dioxide by sampling with impregnated filters

    International Nuclear Information System (INIS)

    Galiano, J.A.; Palomares, F.

    1978-01-01

    The performance of filters impregnated with triethanolamine for the collection and subsequent determination of atmospheric nitrogen dioxide is studied taking into account the influence of several parameters: storage of filters, reagents, elapsed time, sampling efficiency, etc. The results obtained for sampling times of 24 hours are satisfactory. (author) [es

  10. A flexible method for multi-level sample size determination

    International Nuclear Information System (INIS)

    Lu, Ming-Shih; Sanborn, J.B.; Teichmann, T.

    1997-01-01

    This paper gives a flexible method to determine sample sizes for both systematic and random error models (this pertains to sampling problems in nuclear safeguard questions). In addition, the method allows different attribute rejection limits. The new method could assist achieving a higher detection probability and enhance inspection effectiveness

  11. Determination of Phenols in Water Samples using a Supported ...

    African Journals Online (AJOL)

    The sample preparation method was tested for the determination of phenols in river water samples and landfill leachate. Concentrations of phenols in river water were found to be in the range 4.2 μg L–1 for 2-chlorophenol to 50 μg L–1 for 4-chlorophenol. In landfill leachate, 4-chlorophenol was detected at a concentration ...

  12. Determination of average activating thermal neutron flux in bulk samples

    International Nuclear Information System (INIS)

    Doczi, R.; Csikai, J.; Doczi, R.; Csikai, J.; Hassan, F. M.; Ali, M.A.

    2004-01-01

    A previous method used for the determination of the average neutron flux within bulky samples has been applied for the measurements of hydrogen contents of different samples. An analytical function is given for the description of the correlation between the activity of Dy foils and the hydrogen concentrations. Results obtained by the activation and the thermal neutron reflection methods are compared

  13. Focusing light through dynamical samples using fast continuous wavefront optimization.

    Science.gov (United States)

    Blochet, B; Bourdieu, L; Gigan, S

    2017-12-01

    We describe a fast continuous optimization wavefront shaping system able to focus light through dynamic scattering media. A micro-electro-mechanical system-based spatial light modulator, a fast photodetector, and field programmable gate array electronics are combined to implement a continuous optimization of a wavefront with a single-mode optimization rate of 4.1 kHz. The system performances are demonstrated by focusing light through colloidal solutions of TiO 2 particles in glycerol with tunable temporal stability.

  14. Optimal Selection of the Sampling Interval for Estimation of Modal Parameters by an ARMA- Model

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning

    1993-01-01

    Optimal selection of the sampling interval for estimation of the modal parameters by an ARMA-model for a white noise loaded structure modelled as a single degree of- freedom linear mechanical system is considered. An analytical solution for an optimal uniform sampling interval, which is optimal...

  15. Trace determination of uranium in fertilizer samples by total ...

    Indian Academy of Sciences (India)

    the fertilizers is important because it can be used as fuel in nuclear reactors and also because of en- vironmental concerns. ... The amounts of uranium in four fertilizer samples of Hungarian origin were determined by ... TXRF determination of uranium from phosphate fertilizers of Hungarian origin and the preliminary results ...

  16. Determination of uranium in industrial and environmental samples. Vol. 4

    Energy Technology Data Exchange (ETDEWEB)

    El-Sweify, F H; Shehata, M K; Metwally, E M; El-Shazly, E A.A.; El-Naggar, H A [Nuclear Chemistry Department, Hot Laborities Center, Atomic Energy Authority, Cairo (Egypt)

    1996-03-01

    The phosphate ores used at `Abu zaabal fertilizer and chemical company` for the production of some chemicals and fertilizers contain detectable amounts of uranium. In this study, the content of uranium in samples of different products of fertilizers, gypsum, and phosphate ore were determined using NAA, and gamma ray spectroscopy of the irradiated samples. Another method based on measuring the natural radioactivity of {sup 238} U series for non-irradiated samples using gamma-ray spectroscopy was also used for determine uranium content in the samples. In the NAA method, the content of U(ppm) in the samples was been computed from the photopeak activity of the lines = 106.1, 228.2, and 277.5 KeV of {sup 239} Np induced in the irradiated samples, and the uranium standard simultaneously irradiated. the gamma-ray spectra, and the decay curves are given. In the second method the gamma-ray spectra of the natural radioactivity of the samples and uranium standard were measured. The gamma-transition of energies 295.1, 251.9 KeV for {sup 214} Pb; 609.3, 768.4, 1120.3, 1238.1 KeV for {sup 214} Bi were determined. The uranium {sup 23U} traces in drainage water was also determined spectrophotometrically using arsenazo-III after preconcentration of uranium from the pretreated drainage water in column packed with chelex-100 resin. The recovery was found to be 90 {+-} 5%. 11 figs., 3 tabs.

  17. Efficient Round-Trip Time Optimization for Replica-Exchange Enveloping Distribution Sampling (RE-EDS).

    Science.gov (United States)

    Sidler, Dominik; Cristòfol-Clough, Michael; Riniker, Sereina

    2017-06-13

    Replica-exchange enveloping distribution sampling (RE-EDS) allows the efficient estimation of free-energy differences between multiple end-states from a single molecular dynamics (MD) simulation. In EDS, a reference state is sampled, which can be tuned by two types of parameters, i.e., smoothness parameters(s) and energy offsets, such that all end-states are sufficiently sampled. However, the choice of these parameters is not trivial. Replica exchange (RE) or parallel tempering is a widely applied technique to enhance sampling. By combining EDS with the RE technique, the parameter choice problem could be simplified and the challenge shifted toward an optimal distribution of the replicas in the smoothness-parameter space. The choice of a certain replica distribution can alter the sampling efficiency significantly. In this work, global round-trip time optimization (GRTO) algorithms are tested for the use in RE-EDS simulations. In addition, a local round-trip time optimization (LRTO) algorithm is proposed for systems with slowly adapting environments, where a reliable estimate for the round-trip time is challenging to obtain. The optimization algorithms were applied to RE-EDS simulations of a system of nine small-molecule inhibitors of phenylethanolamine N-methyltransferase (PNMT). The energy offsets were determined using our recently proposed parallel energy-offset (PEOE) estimation scheme. While the multistate GRTO algorithm yielded the best replica distribution for the ligands in water, the multistate LRTO algorithm was found to be the method of choice for the ligands in complex with PNMT. With this, the 36 alchemical free-energy differences between the nine ligands were calculated successfully from a single RE-EDS simulation 10 ns in length. Thus, RE-EDS presents an efficient method for the estimation of relative binding free energies.

  18. Optimization of a Pre-MEKC Separation SPE Procedure for Steroid Molecules in Human Urine Samples

    Directory of Open Access Journals (Sweden)

    Ilona Olędzka

    2013-11-01

    Full Text Available Many steroid hormones can be considered as potential biomarkers and their determination in body fluids can create opportunities for the rapid diagnosis of many diseases and disorders of the human body. Most existing methods for the determination of steroids are usually time- and labor-consuming and quite costly. Therefore, the aim of analytical laboratories is to develop a new, relatively low-cost and rapid implementation methodology for their determination in biological samples. Due to the fact that there is little literature data on concentrations of steroid hormones in urine samples, we have made attempts at the electrophoretic determination of these compounds. For this purpose, an extraction procedure for the optimized separation and simultaneous determination of seven steroid hormones in urine samples has been investigated. The isolation of analytes from biological samples was performed by liquid-liquid extraction (LLE with dichloromethane and compared to solid phase extraction (SPE with C18 and hydrophilic-lipophilic balance (HLB columns. To separate all the analytes a micellar electrokinetic capillary chromatography (MECK technique was employed. For full separation of all the analytes a running buffer (pH 9.2, composed of 10 mM sodium tetraborate decahydrate (borax, 50 mM sodium dodecyl sulfate (SDS, and 10% methanol was selected. The methodology developed in this work for the determination of steroid hormones meets all the requirements of analytical methods. The applicability of the method has been confirmed for the analysis of urine samples collected from volunteers—both men and women (students, amateur bodybuilders, using and not applying steroid doping. The data obtained during this work can be successfully used for further research on the determination of steroid hormones in urine samples.

  19. Optimal grade control sampling practice in open-pit mining

    DEFF Research Database (Denmark)

    Engström, Karin; Esbensen, Kim Harry

    2017-01-01

    Misclassification of ore grades results in lost revenues, and the need for representative sampling procedures in open pit mining is increasingly important in all mining industries. This study evaluated possible improvements in sampling representativity with the use of Reverse Circulation (RC) drill...... sampling compared to manual Blast Hole (BH) sampling in the Leveäniemi open pit mine, northern Sweden. The variographic experiment results showed that sampling variability was lower for RC than for BH sampling. However, the total costs for RC drill sampling are significantly exceeding current costs...... for manual BH sampling, which needs to be compensated for by other benefits to motivate introduction of RC drilling. The main conclusion is that manual BH sampling can be fit-for-purpose in the studied open pit mine. However, with so many mineral commodities and mining methods in use globally...

  20. Determining the optimal spacing of deepening of vertical mine

    Energy Technology Data Exchange (ETDEWEB)

    Durov, Ye.M.

    1983-01-01

    Light is shed on a technique for determining the optimal spacing of shafts for deepening for the examined parameters of operational and deepening operations. The presented results of studies may be used in designing new shafts, in preparing levels and in reconstruction of existing shafts with slanted and steep stratum bedding.

  1. Optimal experiment design in a filtering context with application to sampled network data

    OpenAIRE

    Singhal, Harsh; Michailidis, George

    2010-01-01

    We examine the problem of optimal design in the context of filtering multiple random walks. Specifically, we define the steady state E-optimal design criterion and show that the underlying optimization problem leads to a second order cone program. The developed methodology is applied to tracking network flow volumes using sampled data, where the design variable corresponds to controlling the sampling rate. The optimal design is numerically compared to a myopic and a naive strategy. Finally, w...

  2. Sampled-data and discrete-time H2 optimal control

    NARCIS (Netherlands)

    Trentelman, Harry L.; Stoorvogel, Anton A.

    1993-01-01

    This paper deals with the sampled-data H2 optimal control problem. Given a linear time-invariant continuous-time system, the problem of minimizing the H2 performance over all sampled-data controllers with a fixed sampling period can be reduced to a pure discrete-time H2 optimal control problem. This

  3. Determination of uranium and its isotopic ratios in environmental samples

    International Nuclear Information System (INIS)

    Flues Szeles, M.S.M.

    1990-01-01

    A method for the determination of uranium and its isotopic ratios ( sup(235)U/ sup(238)U and sup(234U/ sup(238)U) is established in the present work. The method can be applied in environmental monitoring programs of uranium enrichment facilities. The proposed method is based on the alpha spectrometry technique which is applied after a purification of the sample by using an ionic exchange resin. The total yield achieved was (91 + 5)% with a precision of 5%, an accuracy of 8% and a lower limit of detection of 7,9 x 10 sup(-4)Bq. The uranium determination in samples containing high concentration of iron, which is an interfering element present in environmental samples, particularly in soil and sediment, was also studied. The results obtained by using artificial samples containing iron and uranium in the ratio 1000:1, were considered satisfactory. (author)

  4. Uranium determination in soil samples using Eichrom resins

    International Nuclear Information System (INIS)

    Marabini, S.; Serdeiro, Nelidad H.

    2003-01-01

    Traditionally, the radiochemical methods for uranium activity determination in soil samples by alpha spectrometry, use some techniques like solvent extraction, precipitation and ion exchange in the separation and purification stages. In the last years, some new materials have been developed for using in extraction chromatography, specific for actinides determinations. In the present method the long and tedious stages were eliminated, and the reagents consumption and concentration were minimised. This new procedure was applied to soils since it is one of the most complex matrices. In order to reduce time and chemical reagents, the soil samples up to 0,5 g were leached with nitric, hydrofluoric and perchloric acids in hermetic sealed recipients of Teflon at 150 C degrees during 5 hours. UTEVA Eichrom resin was used for uranium separation and purification. The uranium activity concentration was determined by alpha spectrometry. Several standard samples were analysed and the results are presented. (author)

  5. Sample size determination for mediation analysis of longitudinal data.

    Science.gov (United States)

    Pan, Haitao; Liu, Suyu; Miao, Danmin; Yuan, Ying

    2018-03-27

    Sample size planning for longitudinal data is crucial when designing mediation studies because sufficient statistical power is not only required in grant applications and peer-reviewed publications, but is essential to reliable research results. However, sample size determination is not straightforward for mediation analysis of longitudinal design. To facilitate planning the sample size for longitudinal mediation studies with a multilevel mediation model, this article provides the sample size required to achieve 80% power by simulations under various sizes of the mediation effect, within-subject correlations and numbers of repeated measures. The sample size calculation is based on three commonly used mediation tests: Sobel's method, distribution of product method and the bootstrap method. Among the three methods of testing the mediation effects, Sobel's method required the largest sample size to achieve 80% power. Bootstrapping and the distribution of the product method performed similarly and were more powerful than Sobel's method, as reflected by the relatively smaller sample sizes. For all three methods, the sample size required to achieve 80% power depended on the value of the ICC (i.e., within-subject correlation). A larger value of ICC typically required a larger sample size to achieve 80% power. Simulation results also illustrated the advantage of the longitudinal study design. The sample size tables for most encountered scenarios in practice have also been published for convenient use. Extensive simulations study showed that the distribution of the product method and bootstrapping method have superior performance to the Sobel's method, but the product method was recommended to use in practice in terms of less computation time load compared to the bootstrapping method. A R package has been developed for the product method of sample size determination in mediation longitudinal study design.

  6. Preconcentration NAA for simultaneous multielemental determination in water sample

    International Nuclear Information System (INIS)

    Chatt, A.

    1999-01-01

    Full text: Environment concerns with water, air, land and their interrelationship viz., human beings, fauna and flora. One of the important environmental compartments is water. Elements present in water might face a whole lot of physico-chemical conditions. This poses challenges to measure their total concentrations as well as different species. Preconcentration of the elements present in water samples is a necessary requisites in water analysis. For multi elements concentration measurements, Neutron Activation Analysis (NAA) is one of the preferred analytical techniques due to its sensitivity and selectivity. In this talk preconcentration NAA for multielemental determination in water sample determination will be discussed

  7. Problems in determining the optimal use of road safety measures

    DEFF Research Database (Denmark)

    Elvik, Rune

    2014-01-01

    for intervention that ensures maximum safety benefits. The third problem is how to develop policy options to minimise the risk of indivisibilities and irreversible choices. The fourth problem is how to account for interaction effects between road safety measures when determining their optimal use. The fifth......This paper discusses some problems in determining the optimal use of road safety measures. The first of these problems is how best to define the baseline option, i.e. what will happen if no new safety measures are introduced. The second problem concerns choice of a method for selection of targets...... problem is how to obtain the best mix of short-term and long-term measures in a safety programme. The sixth problem is how fixed parameters for analysis, including the monetary valuation of road safety, influence the results of analyses. It is concluded that it is at present not possible to determine...

  8. Fluorimetrich determination of uranium in mineral samples and phosphoric solutions

    International Nuclear Information System (INIS)

    Pupo Gonzales, I.; Cuevillas, J.; Estevez, J.

    1991-01-01

    In this paper an analytical technique for the determination of uranium in different cuban minerals and acid leaching liquors of phosphorites is proposed. The method used for solid samples includes their disolution and further dilution of the solution obtained. For liquid samples dilution is the only intermediate step used. A study of HNO3 concentration (pH) was made in fluorimetric measurements. The method was applied to the uranium analysis in two IAEA standard reference samples (phosphate base), in natural phosphorites and a synthetic one, in clays and phosphoric liquors. The results agree with those obtained by other methods

  9. Determination of Pu, Am and Cm in Environmental Samples

    Energy Technology Data Exchange (ETDEWEB)

    Lujaniene, G. [SRI Centre for Physical Sciences and Technology, Vilnius (Lithuania)

    2013-07-15

    The determination of actinides in the environmental samples at a lower detection limit is required for monitoring purposes and for environmental research. The method for Pu, Am and Cm measurements in soil and sediment samples provides high recoveries and good decontamination from interfering radionuclides. The main steps of the method involve digestion of the samples, separation of radionuclides from matrix using the TOPO /cyclohexane extraction and final purification using extraction Eichrom resins (TEVA, TRU). The accuracy and precision of Pu, Am and Cm analyses were tested using IAEA RM No 135, NIST SRM No 4350b, No 4357 and in intercomparison runs organized by the Riso National Laboratory, Denmark, and in the proficiency tests organized by National Physical Laboratory, UK. The method was applied for measurement of radionuclides in aerosol samples (ashes {approx}30 g), bottom sediments (50-80 g dr. wt) and soil (including Chernobyl soil) samples. (author)

  10. Determination of tritium in wine and wine yeast samples

    International Nuclear Information System (INIS)

    Cotarlea, Monica-Ionela; Paunescu, Niculina; Galeriu, D.; Mocanu, N.; Margineanu, R.; Marin, G.

    1997-01-01

    A sensitive method for evaluating the tritium content in wine and wine yeast was applied to estimate tritium impact on the environment in the surrounding area of nuclear power plant Cernavoda, where the vineyards are part of representative agricultural ecosystem. Analytical procedures were developed to determine HTO in wine and wine yeast samples. The content of organic compounds affecting the LSC measurement is reduced by fractionating distillation for wine samples and azeotropic distillation followed by fractional distillation for wine yeast samples. Finally, the water samples obtained after fractional distillation were normally distilled with KMO 4 . The established procedures were successfully applied for wine and wine yeast samples from Mulfatlar harvests of the years 1995 and 1996. (authors)

  11. Sample size determination for equivalence assessment with multiple endpoints.

    Science.gov (United States)

    Sun, Anna; Dong, Xiaoyu; Tsong, Yi

    2014-01-01

    Equivalence assessment between a reference and test treatment is often conducted by two one-sided tests (TOST). The corresponding power function and sample size determination can be derived from a joint distribution of the sample mean and sample variance. When an equivalence trial is designed with multiple endpoints, it often involves several sets of two one-sided tests. A naive approach for sample size determination in this case would select the largest sample size required for each endpoint. However, such a method ignores the correlation among endpoints. With the objective to reject all endpoints and when the endpoints are uncorrelated, the power function is the production of all power functions for individual endpoints. With correlated endpoints, the sample size and power should be adjusted for such a correlation. In this article, we propose the exact power function for the equivalence test with multiple endpoints adjusted for correlation under both crossover and parallel designs. We further discuss the differences in sample size for the naive method without and with correlation adjusted methods and illustrate with an in vivo bioequivalence crossover study with area under the curve (AUC) and maximum concentration (Cmax) as the two endpoints.

  12. [Progress on Determination and Analysis of Zopiclone in Biological Samples].

    Science.gov (United States)

    Shu, C X; Gong, D; Zhang, L P; Zhao, J X

    2017-12-01

    As a new hypnotic, zopiclone is widely used in clinical treatment. There are many methods for determination of zopiclone, including spectrophotometry, chromatography and chromatography mass spectrum, etc. Present paper reviews different kinds of biological samples associated with zopiclone, extraction and purification methods, and determination and analysis methods, which aims to provide references for the relevant research and practice. Copyright© by the Editorial Department of Journal of Forensic Medicine.

  13. Sample processing method for the determination of perchlorate in milk

    International Nuclear Information System (INIS)

    Dyke, Jason V.; Kirk, Andrea B.; Kalyani Martinelango, P.; Dasgupta, Purnendu K.

    2006-01-01

    In recent years, many different water sources and foods have been reported to contain perchlorate. Studies indicate that significant levels of perchlorate are present in both human and dairy milk. The determination of perchlorate in milk is particularly important due to its potential health impact on infants and children. As for many other biological samples, sample preparation is more time consuming than the analysis itself. The concurrent presence of large amounts of fats, proteins, carbohydrates, etc., demands some initial cleanup; otherwise the separation column lifetime and the limit of detection are both greatly compromised. Reported milk processing methods require the addition of chemicals such as ethanol, acetic acid or acetonitrile. Reagent addition is undesirable in trace analysis. We report here an essentially reagent-free sample preparation method for the determination of perchlorate in milk. Milk samples are spiked with isotopically labeled perchlorate and centrifuged to remove lipids. The resulting liquid is placed in a disposable centrifugal ultrafilter device with a molecular weight cutoff of 10 kDa, and centrifuged. Approximately 5-10 ml of clear liquid, ready for analysis, is obtained from a 20 ml milk sample. Both bovine and human milk samples have been successfully processed and analyzed by ion chromatography-mass spectrometry (IC-MS). Standard addition experiments show good recoveries. The repeatability of the analytical result for the same sample in multiple sample cleanup runs ranged from 3 to 6% R.S.D. This processing technique has also been successfully applied for the determination of iodide and thiocyanate in milk

  14. Determining sample size for assessing species composition in ...

    African Journals Online (AJOL)

    Species composition is measured in grasslands for a variety of reasons. Commonly, observations are made using the wheel-point apparatus, but the problem of determining optimum sample size has not yet been satisfactorily resolved. In this study the wheel-point apparatus was used to record 2 000 observations in each of ...

  15. Determination of thiobencarb in water samples by gas ...

    African Journals Online (AJOL)

    Homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA) coupled with gas chromatography-flame ionization detection (GC-FID) was applied for the extraction and determination of thiobencarb in water samples. In this study, a special extraction cell was designed to facilitate collection of the ...

  16. Determination of lead at nanogram level in water samples by ...

    African Journals Online (AJOL)

    A novel method of chemistry applicable to the determination of trace lead in water samples based on the resonance light scattering (RLS) technique has been developed. In dilute phosphoric acid medium, in the presence of a large excess of I-, Pb(II) can form [PbI4]2-, which further reacts with tetrabutyl ammonium bromide ...

  17. Improved sample capsule for determination of oxygen in hemolyzed blood

    Science.gov (United States)

    Malik, W. M.

    1967-01-01

    Sample capsule for determination of oxygen in hemolyzed blood consists of a measured section of polytetrafluoroethylene tubing equipped at each end with a connector and a stopcock valve. This method eliminates errors from air entrainment or from the use of mercury or syringe lubricant.

  18. Determination of thorium and uranium contents in soil samples ...

    Indian Academy of Sciences (India)

    using CR-39 and LR-115-II solid-state nuclear track detectors (SSNTDs). ... standard soil samples have been determined and compared with its known values. ... measure α-tracks activity [1], where SSNTDs have been used in geology [2–6] ...

  19. Experimental determination of size distributions: analyzing proper sample sizes

    International Nuclear Information System (INIS)

    Buffo, A; Alopaeus, V

    2016-01-01

    The measurement of various particle size distributions is a crucial aspect for many applications in the process industry. Size distribution is often related to the final product quality, as in crystallization or polymerization. In other cases it is related to the correct evaluation of heat and mass transfer, as well as reaction rates, depending on the interfacial area between the different phases or to the assessment of yield stresses of polycrystalline metals/alloys samples. The experimental determination of such distributions often involves laborious sampling procedures and the statistical significance of the outcome is rarely investigated. In this work, we propose a novel rigorous tool, based on inferential statistics, to determine the number of samples needed to obtain reliable measurements of size distribution, according to specific requirements defined a priori. Such methodology can be adopted regardless of the measurement technique used. (paper)

  20. Determination of technetium-99 in environmental samples: A review

    DEFF Research Database (Denmark)

    Shi, Keliang; Hou, Xiaolin; Roos, Per

    2012-01-01

    Due to the lack of a stable technetium isotope, and the high mobility and long half-life, 99Tc is considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. 99Tc is also an important tracer for oceanographic...... research due to the high technetium solubility in seawater as TcO4−. A number of analytical methods, using chemical separation combined with radiometric and mass spectrometric measurement techniques, have been developed over the past decades for determination of 99Tc in different environmental samples....... This article summarizes and compares recently reported chemical separation procedures and measurement methods for determination of 99Tc. Due to the extremely low concentration of 99Tc in environmental samples, the sample preparation, pre-concentration, chemical separation and purification for removal...

  1. Biomass Thermogravimetric Analysis: Uncertainty Determination Methodology and Sampling Maps Generation

    Science.gov (United States)

    Pazó, Jose A.; Granada, Enrique; Saavedra, Ángeles; Eguía, Pablo; Collazo, Joaquín

    2010-01-01

    The objective of this study was to develop a methodology for the determination of the maximum sampling error and confidence intervals of thermal properties obtained from thermogravimetric analysis (TG), including moisture, volatile matter, fixed carbon and ash content. The sampling procedure of the TG analysis was of particular interest and was conducted with care. The results of the present study were compared to those of a prompt analysis, and a correlation between the mean values and maximum sampling errors of the methods were not observed. In general, low and acceptable levels of uncertainty and error were obtained, demonstrating that the properties evaluated by TG analysis were representative of the overall fuel composition. The accurate determination of the thermal properties of biomass with precise confidence intervals is of particular interest in energetic biomass applications. PMID:20717532

  2. Rapid and automated determination of plutonium and neptunium in environmental samples

    International Nuclear Information System (INIS)

    Qiao, J.

    2011-03-01

    This thesis presents improved analytical methods for rapid and automated determination of plutonium and neptunium in environmental samples using sequential injection (SI) based chromatography and inductively coupled plasma mass spectrometry (ICP-MS). The progress of methodology development in this work consists of 5 subjects stated as follows: 1) Development and optimization of an SI-anion exchange chromatographic method for rapid determination of plutonium in environmental samples in combination of inductively coupled plasma mass spectrometry detection (Paper II); (2) Methodology development and optimization for rapid determination of plutonium in environmental samples using SI-extraction chromatography prior to inductively coupled plasma mass spectrometry (Paper III); (3) Development of an SI-chromatographic method for simultaneous determination of plutonium and neptunium in environmental samples (Paper IV); (4) Investigation of the suitability and applicability of 242 Pu as a tracer for rapid neptunium determination using anion exchange chromatography in an SI-network coupled with inductively coupled plasma mass spectrometry (Paper V); (5) Exploration of macro-porous anion exchange chromatography for rapid and simultaneous determination of plutonium and neptunium within an SI system (Paper VI). The results demonstrate that the developed methods in this study are reliable and efficient for accurate assays of trace levels of plutonium and neptunium as demanded in different situations including environmental risk monitoring and assessment, emergency preparedness and surveillance of contaminated areas. (Author)

  3. Rapid and automated determination of plutonium and neptunium in environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, J.

    2011-03-15

    This thesis presents improved analytical methods for rapid and automated determination of plutonium and neptunium in environmental samples using sequential injection (SI) based chromatography and inductively coupled plasma mass spectrometry (ICP-MS). The progress of methodology development in this work consists of 5 subjects stated as follows: 1) Development and optimization of an SI-anion exchange chromatographic method for rapid determination of plutonium in environmental samples in combination of inductively coupled plasma mass spectrometry detection (Paper II); (2) Methodology development and optimization for rapid determination of plutonium in environmental samples using SI-extraction chromatography prior to inductively coupled plasma mass spectrometry (Paper III); (3) Development of an SI-chromatographic method for simultaneous determination of plutonium and neptunium in environmental samples (Paper IV); (4) Investigation of the suitability and applicability of 242Pu as a tracer for rapid neptunium determination using anion exchange chromatography in an SI-network coupled with inductively coupled plasma mass spectrometry (Paper V); (5) Exploration of macro-porous anion exchange chromatography for rapid and simultaneous determination of plutonium and neptunium within an SI system (Paper VI). The results demonstrate that the developed methods in this study are reliable and efficient for accurate assays of trace levels of plutonium and neptunium as demanded in different situations including environmental risk monitoring and assessment, emergency preparedness and surveillance of contaminated areas. (Author)

  4. Determination of uranium and thorium by neutron activation analysis applied to fossil samples dating

    International Nuclear Information System (INIS)

    Ticianelli, Regina B.; Figueiredo, Ana Maria Graciano; Zahn, Guilherme S.; Kinoshita, Angela; Baffa, Oswaldo

    2011-01-01

    Electron Spin Resonance (ESR) dating is based on the fact that ionizing radiation can create stable free radicals in insulating materials, like tooth enamel and bones. The concentration of these radicals - determined by ESR - is a function of the dose deposed in the sample along the years. The accumulated dose of radiation, called Archaeological Dose, is produced by the exposition to environmental radiation provided by U, Th, K and cosmic rays. If the environmental dose rate in the site where the fossil sample is found is known, it is possible to convert this dose into the age of the sample. The annual dose rate coming from the radioactive elements present in the soil and in the sample itself can be calculated by determining the U, Th and K concentration. Therefore, the determination of the dose rate depends on the concentration of these main radioactive elements. Neutron Activation Analysis has the sensitivity and the accuracy necessary to determine U, Th and K with this objective. Depending on the composition of the sample, the determination of U and Th can be improved irradiating the sample inside a Cd capsule, reducing the thermal neutron incidence on the sample and, therefore, diminishing the activation of possible interfering nuclides. In this study the optimal irradiation and counting conditions were established for U and Th determination in fossil teeth and soil. (author)

  5. Wildlife Conservation Planning Using Stochastic Optimization and Importance Sampling

    Science.gov (United States)

    Robert G. Haight; Laurel E. Travis

    1997-01-01

    Formulations for determining conservation plans for sensitive wildlife species must account for economic costs of habitat protection and uncertainties about how wildlife populations will respond. This paper describes such a formulation and addresses the computational challenge of solving it. The problem is to determine the cost-efficient level of habitat protection...

  6. Particle swarm optimization for determining shortest distance to voltage collapse

    Energy Technology Data Exchange (ETDEWEB)

    Arya, L.D.; Choube, S.C. [Electrical Engineering Department, S.G.S.I.T.S. Indore, MP 452 003 (India); Shrivastava, M. [Electrical Engineering Department, Government Engineering College Ujjain, MP 456 010 (India); Kothari, D.P. [Centre for Energy Studies, Indian Institute of Technology, Delhi (India)

    2007-12-15

    This paper describes an algorithm for computing shortest distance to voltage collapse or determination of CSNBP using PSO technique. A direction along CSNBP gives conservative results from voltage security view point. This information is useful to the operator to steer the system away from this point by taking corrective actions. The distance to a closest bifurcation is a minimum of the loadability given a slack bus or participation factors for increasing generation as the load increases. CSNBP determination has been formulated as an optimization problem to be used in PSO technique. PSO is a new evolutionary algorithm (EA) which is population based inspired by the social behavior of animals such as fish schooling and birds flocking. It can handle optimization problems with any complexity since mechanization is simple with few parameters to be tuned. The developed algorithm has been implemented on two standard test systems. (author)

  7. Optimism is universal: exploring the presence and benefits of optimism in a representative sample of the world.

    Science.gov (United States)

    Gallagher, Matthew W; Lopez, Shane J; Pressman, Sarah D

    2013-10-01

    Current theories of optimism suggest that the tendency to maintain positive expectations for the future is an adaptive psychological resource associated with improved well-being and physical health, but the majority of previous optimism research has been conducted in industrialized nations. The present study examined (a) whether optimism is universal, (b) what demographic factors predict optimism, and (c) whether optimism is consistently associated with improved subjective well-being and perceived health worldwide. The present study used representative samples of 142 countries that together represent 95% of the world's population. The total sample of 150,048 individuals had a mean age of 38.28 (SD = 16.85) and approximately equal sex distribution (51.2% female). The relationships between optimism, subjective well-being, and perceived health were examined using hierarchical linear modeling. Results indicated that most individuals and most countries worldwide are optimistic and that higher levels of optimism are associated with improved subjective well-being and perceived health worldwide. The present study provides compelling evidence that optimism is a universal phenomenon and that the associations between optimism and improved psychological functioning are not limited to industrialized nations. © 2012 Wiley Periodicals, Inc.

  8. Optimization of determination of 126Sn by ion exchange chromatography method (presentation)

    International Nuclear Information System (INIS)

    Pasteka, L.; Dulanska, S.

    2013-01-01

    The aim of the work is to optimize the uptake of tin on anion exchange resins and application of this knowledge for the analysis of samples of radioactive waste from the device of Jaslovske Bohunice and Mochovce in determining of 126 Sn. First to be optimized a method for the separation of tin on ion exchange sorbent Anion Exchange Resin (1-X8, Chloride Form) from Eichrom Technologies. Model sample was prepared in 7 mol dm -3 HCl, because in that environment a sorbent effectively captures the tin, which is bounded complexly with chloride anions as SnCl 6 2- . The radiochemical separation yield was monitored by gamma spectrometric measurements on high purity germanium detector HPGe (E = 391 keV) by adding isotope 113 Sn to each model solution. The method of tin separation was optimized on model samples.

  9. Solid Phase Microextraction (SPME in Determination of Pesticide Residues in Soil Samples

    Directory of Open Access Journals (Sweden)

    Rada Đurović

    2011-01-01

    Full Text Available The basic principles and application possibilities of the methods based on solid phase microextraction (SPME in the analysis of pesticide residues in soil samples are presented in the paper. The most important experimental parameters which affect SPME efficacy inpesticide determination (type and thickness of microextraction fiber, duration of microextraction,temperature at which it is conducted, effect of addition of salts (the effect of efflorescence,temperature and time of desorption, the choice of optimal solvent for pesticide exctraction from the soil and the optimal number of extraction steps, as well as general guidelines for their optimization are also shown. In the end, current applications of SPMEmethods in the analysis of pesticide residues in soil samples are presented.

  10. Rapid and Automated Determination of Plutonium and Neptunium in Environmental Samples

    DEFF Research Database (Denmark)

    Qiao, Jixin

    This thesis presents improved analytical methods for rapid and automated determination of plutonium and neptunium in environmental samples using sequential injection (SI) based chromatography and inductively coupled plasma mass spectrometry (ICP-MS). The progress of methodology development...... and optimization for rapid determination of plutonium in environmental samples using SIextraction chromatography prior to inductively coupled plasma mass spectrometry (Paper III); (3) Development of an SI-chromatographic method for simultaneous determination of plutonium and neptunium in environmental samples...... for rapid and simultaneous determination of plutonium and neptunium within an SI system (Paper VI). The results demonstrate that the developed methods in this study are reliable and efficient for accurate assays of trace levels of plutonium and neptunium as demanded in different situations including...

  11. Quality Control Samples for the Radiological Determination of Tritium in Urine Samples

    International Nuclear Information System (INIS)

    Ost'pezuk, P.; Froning, M.; Laumen, S.; Richert, I.; Hill, P.

    2004-01-01

    The radioactive decay product of tritium is a low energy beta that cannot penetrate the outer dead layer of human skin. Therefore , the main hazard associated with tritium is internal exposure. In addition, due to the relatively long half life and short biological half life, tritium must be ingested in large amounts to pose a significant health risk. On the other hand, the internal exposure should be kept as low as practical. For incorporation monitoring of professional radiation workers the quality control is of utmost importance. In the Research Centre Juelich GmbH (FZJ) a considerable fraction of monitoring by excretion analysis relates to the isotope Tritium. Usually an aliquot of an urine sample is mixed with a liquid scintillator and measured in a liquid scintillation counter. Quality control samples in the form of three kind of internal reference samples (blank, reference samples with low activity and reference sample with elevated activity) were prepared from a mixed, Tritium (free) urine samples. 1 ml of these samples were pipetted into a liquid scintillation vial. In the part of theses vials a known amounts of Tritium were added. All these samples were stored at 20 degrees. Based on long term use of all these reference samples it was possible to construct appropriate control charts with the upper and lower alarm limits. Daily use of these reference samples decrease significantly the risk for false results in original urine with no significant increase of the determination time. (Author) 2 refs

  12. Conservative Sample Size Determination for Repeated Measures Analysis of Covariance.

    Science.gov (United States)

    Morgan, Timothy M; Case, L Douglas

    2013-07-05

    In the design of a randomized clinical trial with one pre and multiple post randomized assessments of the outcome variable, one needs to account for the repeated measures in determining the appropriate sample size. Unfortunately, one seldom has a good estimate of the variance of the outcome measure, let alone the correlations among the measurements over time. We show how sample sizes can be calculated by making conservative assumptions regarding the correlations for a variety of covariance structures. The most conservative choice for the correlation depends on the covariance structure and the number of repeated measures. In the absence of good estimates of the correlations, the sample size is often based on a two-sample t-test, making the 'ultra' conservative and unrealistic assumption that there are zero correlations between the baseline and follow-up measures while at the same time assuming there are perfect correlations between the follow-up measures. Compared to the case of taking a single measurement, substantial savings in sample size can be realized by accounting for the repeated measures, even with very conservative assumptions regarding the parameters of the assumed correlation matrix. Assuming compound symmetry, the sample size from the two-sample t-test calculation can be reduced at least 44%, 56%, and 61% for repeated measures analysis of covariance by taking 2, 3, and 4 follow-up measures, respectively. The results offer a rational basis for determining a fairly conservative, yet efficient, sample size for clinical trials with repeated measures and a baseline value.

  13. METHODS FOR DETERMINATION AND OPTIMIZATION OF LOGISTICS COSTS

    Directory of Open Access Journals (Sweden)

    Mihaela STET

    2016-12-01

    Full Text Available The paper is dealing with the problems of logistics costs, highlighting some methods for estimation and determination of specific costs for different transport modes in freight distribution. There are highlighted, besides costs of transports, the other costs in supply chain, as well as costing methods used in logistics activities. In this context, there are also revealed some optimization means of transport costs in logistics chain.

  14. METHODS FOR DETERMINATION AND OPTIMIZATION OF LOGISTICS COSTS

    OpenAIRE

    Mihaela STET

    2016-01-01

    The paper is dealing with the problems of logistics costs, highlighting some methods for estimation and determination of specific costs for different transport modes in freight distribution. There are highlighted, besides costs of transports, the other costs in supply chain, as well as costing methods used in logistics activities. In this context, there are also revealed some optimization means of transport costs in logistics chain.

  15. Determination of nitrite, nitrate and total nitrogen in vegetable samples

    Directory of Open Access Journals (Sweden)

    Manas Kanti Deb

    2007-04-01

    Full Text Available Yellow diazonium cation formed by reaction of nitrite with 6-amino-1-naphthol-3-sulphonic acid is coupled with β-naphthol in strong alkaline medium to yield a pink coloured azo dye. The azo-dyes shows absorption maximum at 510 nm with molar absorptivity of 2.5 ×104 M-1 cm-1. The dye product obeys Beer's law (correlation coefficient = 0.997, in terms of nitrite concentration, up to 2.7 μg NO2 mL-1. The above colour reaction system has been applied successfully for the determination of nitrite, nitrate and total nitrogen in vegetable samples. Unreduced samples give direct measure for nitrite whilst reduction of samples by copperized-cadmium column gives total nitrogen content and their difference shows nitrate content in the samples. Variety of vegetables have been tested for their N-content (NO2-/NO3-/total-N with % RSD ranging between 1.5 to 2.5 % for nitrite determination. The effects of foreign ions in the determination of the nitrite, nitrate, and total nitrogen have been studied. Statistical comparison of the results with those of reported method shows good agreement and indicates no significant difference in precision.

  16. Determination of sampling constants in NBS geochemical standard reference materials

    International Nuclear Information System (INIS)

    Filby, R.H.; Bragg, A.E.; Grimm, C.A.

    1986-01-01

    Recently Filby et al. showed that, for several elements, National Bureau of Standards (NBS) Fly Ash standard reference material (SRM) 1633a was a suitable reference material for microanalysis (sample weights 2 , and the mean sample weight, W vector, K/sub s/ = (S/sub s/%) 2 W vector, could not be determined from these data because it was not possible to quantitate other sources of error in the experimental variances. K/sub s/ values for certified elements in geochemical SRMs provide important homogeneity information for microanalysis. For mineralogically homogeneous SRMs (i.e., small K/sub s/ values for associated elements) such as the proposed clays, it is necessary to determine K/sub s/ by analysis of very small sample aliquots to maximize the subsampling variance relative to other sources of error. This source of error and the blank correction for the sample container can be eliminated by determining K/sub s/ from radionuclide activities of weighed subsamples of a preirradiated SRM

  17. [Application of simulated annealing method and neural network on optimizing soil sampling schemes based on road distribution].

    Science.gov (United States)

    Han, Zong-wei; Huang, Wei; Luo, Yun; Zhang, Chun-di; Qi, Da-cheng

    2015-03-01

    Taking the soil organic matter in eastern Zhongxiang County, Hubei Province, as a research object, thirteen sample sets from different regions were arranged surrounding the road network, the spatial configuration of which was optimized by the simulated annealing approach. The topographic factors of these thirteen sample sets, including slope, plane curvature, profile curvature, topographic wetness index, stream power index and sediment transport index, were extracted by the terrain analysis. Based on the results of optimization, a multiple linear regression model with topographic factors as independent variables was built. At the same time, a multilayer perception model on the basis of neural network approach was implemented. The comparison between these two models was carried out then. The results revealed that the proposed approach was practicable in optimizing soil sampling scheme. The optimal configuration was capable of gaining soil-landscape knowledge exactly, and the accuracy of optimal configuration was better than that of original samples. This study designed a sampling configuration to study the soil attribute distribution by referring to the spatial layout of road network, historical samples, and digital elevation data, which provided an effective means as well as a theoretical basis for determining the sampling configuration and displaying spatial distribution of soil organic matter with low cost and high efficiency.

  18. Determination of technetium-99 in environmental samples: A review

    International Nuclear Information System (INIS)

    Shi Keliang; Hou Xiaolin; Roos, Per; Wu Wangsuo

    2012-01-01

    Highlights: ► The source term, physicochemical properties, environmental distribution and behaviour of 99 Tc are presented. ► Various sample pre-treatment and pre-concentration techniques of technetium are discussed. ► Chemical separation and purification techniques for 99 Tc in environmental samples are reviewed. ► Measurement techniques for 99 Tc in environmental level and automated analytical methods are reviewed. ► The reported analytical methods of 99 Tc are critically compared to provide overall information. - Abstract: Due to the lack of a stable technetium isotope, and the high mobility and long half-life, 99 Tc is considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. 99 Tc is also an important tracer for oceanographic research due to the high technetium solubility in seawater as TcO 4 − . A number of analytical methods, using chemical separation combined with radiometric and mass spectrometric measurement techniques, have been developed over the past decades for determination of 99 Tc in different environmental samples. This article summarizes and compares recently reported chemical separation procedures and measurement methods for determination of 99 Tc. Due to the extremely low concentration of 99 Tc in environmental samples, the sample preparation, pre-concentration, chemical separation and purification for removal of the interferences for detection of 99 Tc are the most important issues governing the accurate determination of 99 Tc. These aspects are discussed in detail in this article. Meanwhile, the different measurement techniques for 99 Tc are also compared with respect to advantages and drawbacks. Novel automated analytical methods for rapid determination of 99 Tc using solid extraction or ion exchange chromatography for separation of 99 Tc, employing flow injection or sequential injection approaches are also discussed.

  19. Microwave-assisted extraction and mild saponification for determination of organochlorine pesticides in oyster samples.

    Science.gov (United States)

    Carro, N; García, I; Ignacio, M-C; Llompart, M; Yebra, M-C; Mouteira, A

    2002-10-01

    A sample-preparation procedure (extraction and saponification) using microwave energy is proposed for determination of organochlorine pesticides in oyster samples. A Plackett-Burman factorial design has been used to optimize the microwave-assisted extraction and mild saponification on a freeze dried sample spiked with a mixture of aldrin, endrin, dieldrin, heptachlor, heptachorepoxide, isodrin, transnonachlor, p, p'-DDE, and p, p'-DDD. Six variables: solvent volume, extraction time, extraction temperature, amount of acetone (%) in the extractant solvent, amount of sample, and volume of NaOH solution were considered in the optimization process. The results show that the amount of sample is statistically significant for dieldrin, aldrin, p, p'-DDE, heptachlor, and transnonachlor and solvent volume for dieldrin, aldrin, and p, p'-DDE. The volume of NaOH solution is statistically significant for aldrin and p, p'-DDE only. Extraction temperature and extraction time seem to be the main factors determining the efficiency of extraction process for isodrin and p, p'-DDE, respectively. The optimized procedure was compared with conventional Soxhlet extraction.

  20. System to determine present elements in oily samples

    International Nuclear Information System (INIS)

    Mendoza G, Y.

    2004-11-01

    In the Chemistry Department of the National Institute of Nuclear Investigations of Mexico, dedicated to analyze samples of oleaginous material and of another origin, to determine the elements of the periodic table present in the samples, through the Neutron activation analysis technique (NAA). This technique has been developed to determine majority elements in any solid, aqueous, industrial and environmental sample, which consists basically on to irradiate a sample with neutrons coming from the TRIGA Mark III reactor and to carry out the analysis to obtain those gamma spectra that it emits, for finally to process the information, the quantification of the analysis it is carried out in a manual way, which requires to carry out a great quantity of calculations. The main objective of this project is the development of a software that allows to carry out the quantitative analysis of the NAA for the multielemental determination of samples in an automatic way. To fulfill the objective of this project it has been divided in four chapters: In the first chapter it is shortly presented the history on radioactivity and basic concepts that will allow us penetrate better to this work. In the second chapter the NAA is explained which is used in the sample analysis, the description of the process to be carried out, its are mentioned the characteristics of the used devices and an example of the process is illustrated. In the third chapter it is described the development of the algorithm and the selection of the programming language. The fourth chapter it is shown the structure of the system, the general form of operation, the execution of processes and the obtention of results. Later on the launched results are presented in the development of the present project. (Author)

  1. Determination of 210Pb and 210Po in water samples

    International Nuclear Information System (INIS)

    Ayranov, M.; Tosheva, Z.; Kies, A.

    2004-01-01

    Lead-210 and Polonium-210 are naturally occurring members of the Uranium-238 decay series. They could be found in various environmental samples, such as groundwater, fish and shellfish, contributing an important component of the human natural radiation background. For this reason the development of a fast, reproducible and sensitive method for determination of 210 Pb and 210 Po is of a great concern. The aims of our study were to adopt procedures for radiochemical separation of these radionuclides and radioanalytical methods for their determination. The combination of electrochemical deposition, co-precipitation and extraction chromatography gives the opportunity for fast and effective radiochemical separation of the analytes. Polonium was spontaneously plated on copper disk from the stock solution. Lead was co-precipitated with Fe(OH) 3 and further purified by extraction chromatography on Sr Spec columns. Alpha spectra of polonium were collected on Canberra PIPS detectors with 900 mm 2 active surface. The activities of lead were determined by LSC (Gardian Wallac Oy). The minimum detectable activities for sample size 1000 mL and chemical yield of 88 % for the polonium and 85 % for the lead are presented. The proposed method proved to be fast, accurate and reproducible for routine determination of lead and polonium in environmental water samples. (authors)

  2. Determination of Sr-90 in rain water samples

    International Nuclear Information System (INIS)

    Lima, M.F.; Cunha, I.I.L.

    1988-01-01

    A work that aim is to establish radiochemical method for the determination of Sr-90 in rain water samples has been studied, as a step in an environmental monitoring program of radioactive elements. The analysis includes the preconcentration of strontium diluted in a large volume sample by precipitation of strontium as carbonate, separation of strontium from interfering elements (calcium, barium and rare earths), separation of strontium from ytrium, precipitation of purified strontium and ytrium respectively as carbonate and oxalate, and counting of Sr-90 and Y-90 activities in a low background anticoincidence beta counter. (author) [pt

  3. A review of sample preparation and its influence on pH determination in concrete samples

    International Nuclear Information System (INIS)

    Manso, S.; Aguado, A.

    2017-01-01

    If we are to monitor the chemical processes in cementitious materials, then pH assays in the pore solutions of cement pastes, mortars, and concretes are of key importance. However, there is no standard method that regulates the sample-preparation method for pH determination. The state-of-the-art of different methods for pH determination in cementitious materials is presented in this paper and the influence of sample preparation in each case. Moreover, an experimental campaign compares three different techniques for pH determination. Its results contribute to establishing a basic criterion to help researchers select the most suitable method, depending on the purpose of the research. A simple tool is described for selecting the easiest and the most economic pH determination method, depending on the objective; especially for researchers and those with limited experience in this field.

  4. A review of sample preparation and its influence on pH determination in concrete samples

    Directory of Open Access Journals (Sweden)

    S. Manso

    2017-01-01

    Full Text Available If we are to monitor the chemical processes in cementitious materials, then pH assays in the pore solutions of cement pastes, mortars, and concretes are of key importance. However, there is no standard method that regulates the sample-preparation method for pH determination. The state-of-the-art of different methods for pH determination in cementitious materials is presented in this paper and the influence of sample preparation in each case. Moreover, an experimental campaign compares three different techniques for pH determination. Its results contribute to establishing a basic criterion to help researchers select the most suitable method, depending on the purpose of the research. A simple tool is described for selecting the easiest and the most economic pH determination method, depending on the objective; especially for researchers and those with limited experience in this field.

  5. [Sampling optimization for tropical invertebrates: an example using dung beetles (Coleoptera: Scarabaeinae) in Venezuela].

    Science.gov (United States)

    Ferrer-Paris, José Rafael; Sánchez-Mercado, Ada; Rodríguez, Jon Paul

    2013-03-01

    The development of efficient sampling protocols is an essential prerequisite to evaluate and identify priority conservation areas. There are f ew protocols for fauna inventory and monitoring in wide geographical scales for the tropics, where the complexity of communities and high biodiversity levels, make the implementation of efficient protocols more difficult. We proposed here a simple strategy to optimize the capture of dung beetles, applied to sampling with baited traps and generalizable to other sampling methods. We analyzed data from eight transects sampled between 2006-2008 withthe aim to develop an uniform sampling design, that allows to confidently estimate species richness, abundance and composition at wide geographical scales. We examined four characteristics of any sampling design that affect the effectiveness of the sampling effort: the number of traps, sampling duration, type and proportion of bait, and spatial arrangement of the traps along transects. We used species accumulation curves, rank-abundance plots, indicator species analysis, and multivariate correlograms. We captured 40 337 individuals (115 species/morphospecies of 23 genera). Most species were attracted by both dung and carrion, but two thirds had greater relative abundance in traps baited with human dung. Different aspects of the sampling design influenced each diversity attribute in different ways. To obtain reliable richness estimates, the number of traps was the most important aspect. Accurate abundance estimates were obtained when the sampling period was increased, while the spatial arrangement of traps was determinant to capture the species composition pattern. An optimum sampling strategy for accurate estimates of richness, abundance and diversity should: (1) set 50-70 traps to maximize the number of species detected, (2) get samples during 48-72 hours and set trap groups along the transect to reliably estimate species abundance, (3) set traps in groups of at least 10 traps to

  6. Optimizing 4-Dimensional Magnetic Resonance Imaging Data Sampling for Respiratory Motion Analysis of Pancreatic Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Stemkens, Bjorn, E-mail: b.stemkens@umcutrecht.nl [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands); Tijssen, Rob H.N. [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands); Senneville, Baudouin D. de [Imaging Division, University Medical Center Utrecht, Utrecht (Netherlands); L' Institut de Mathématiques de Bordeaux, Unité Mixte de Recherche 5251, Centre National de la Recherche Scientifique/University of Bordeaux, Bordeaux (France); Heerkens, Hanne D.; Vulpen, Marco van; Lagendijk, Jan J.W.; Berg, Cornelis A.T. van den [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands)

    2015-03-01

    Purpose: To determine the optimum sampling strategy for retrospective reconstruction of 4-dimensional (4D) MR data for nonrigid motion characterization of tumor and organs at risk for radiation therapy purposes. Methods and Materials: For optimization, we compared 2 surrogate signals (external respiratory bellows and internal MRI navigators) and 2 MR sampling strategies (Cartesian and radial) in terms of image quality and robustness. Using the optimized protocol, 6 pancreatic cancer patients were scanned to calculate the 4D motion. Region of interest analysis was performed to characterize the respiratory-induced motion of the tumor and organs at risk simultaneously. Results: The MRI navigator was found to be a more reliable surrogate for pancreatic motion than the respiratory bellows signal. Radial sampling is most benign for undersampling artifacts and intraview motion. Motion characterization revealed interorgan and interpatient variation, as well as heterogeneity within the tumor. Conclusions: A robust 4D-MRI method, based on clinically available protocols, is presented and successfully applied to characterize the abdominal motion in a small number of pancreatic cancer patients.

  7. Using the modified sample entropy to detect determinism

    Energy Technology Data Exchange (ETDEWEB)

    Xie Hongbo, E-mail: xiehb@sjtu.or [Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Department of Biomedical Engineering, Jiangsu University, Zhenjiang (China); Guo Jingyi [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Zheng Yongping, E-mail: ypzheng@ieee.or [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Reseach Institute of Innovative Products and Technologies, Hong Kong Polytechnic University (Hong Kong)

    2010-08-23

    A modified sample entropy (mSampEn), based on the nonlinear continuous and convex function, has been proposed and proven to be superior to the standard sample entropy (SampEn) in several aspects. In this Letter, we empirically investigate the ability of the mSampEn statistic combined with surrogate data method to detect determinism. The effects of the datasets length and noise on the proposed method to differentiate between deterministic and stochastic dynamics are tested on several benchmark time series. The noise performance of the mSampEn statistic is also compared with the singular value decomposition (SVD) and symplectic geometry spectrum (SGS) based methods. The results indicate that the mSampEn statistic is a robust index for detecting determinism in short and noisy time series.

  8. Problem of cadmium, arsenic and zinc determination in enviroment samples

    International Nuclear Information System (INIS)

    Malyugin, M.S.; Luzhnova, M.A.; Lontsikh, S.V.

    1983-01-01

    Using the emission spectroscopy technique new information has been obtained on cadmium-, arsenic and zinc content in some reference samples (RS) of rocks and soils not previously certified as to the content of the elements, as well as in nealy issued RS of soils. Metrologic estimation of the results obtained is carried out. A comparison with the atomic-absorption analysis data as well as with those of the neutron-activation-, colorimetric and other methods of the analysis permits to refer to the advantages of using the spectrographic determination technique based on fractionated evaporation, in case of determining cadmium and arsenic in rocks and soils. Consideration of the results of cadmium, arsenic and zinc spectrography contributed greatly to the certification of reference samples of soils

  9. A PROCEDURE FOR DETERMINING OPTIMAL FACILITY LOCATION AND SUB-OPTIMAL POSITIONS

    Directory of Open Access Journals (Sweden)

    P.K. Dan

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: This research presents a methodology for determining the optimal location of a new facility, having physical flow interaction of various degrees with other existing facilities in the presence of barriers impeding the shortest flow-path as well as the sub-optimal iso-cost positions. It also determines sub-optimal iso-cost positions with additional cost or penalty for not being able to site it at the computed optimal point. The proposed methodology considers all types of quadrilateral barrier or forbidden region configurations to generalize and by-pass such impenetrable obstacles, and adopts a scheme of searching through the vertices of the quadrilaterals to determine the alternative shortest flow-path. This procedure of obstacle avoidance is novel. Software has been developed to facilitate computations for the search algorithm to determine the optimal and iso-cost co-ordinates. The test results are presented.

    AFRIKAANSE OPSOMMING: Die navorsing behandel ‘n procedure vir die bepaling van optimum stigtingsposisie vir ‘n onderneming met vloei vanaf ander bestaande fasiliteite in die teenwoordigheid van ‘n verskeidenheid van randvoorwaardes. Die prodedure lewer as resultaat suboptimale isokoste-stigtingsplekke met bekendmaking van die koste wat onstaan a.g.v. afwyking van die randvoorwaardlose optimum oplossingskoste, die prosedure maak gebruik van ‘n vindingryke soekmetode wat toegepas word op niersydige meerkundige voorstellings vir die bepaling van korste roetes wat versperring omseil. Die prosedure word onderskei deur programmatuur. Toetsresultate word voorgehou.

  10. Optimal sampling plan for clean development mechanism lighting projects with lamp population decay

    International Nuclear Information System (INIS)

    Ye, Xianming; Xia, Xiaohua; Zhang, Jiangfeng

    2014-01-01

    Highlights: • A metering cost minimisation model is built with the lamp population decay to optimise CDM lighting projects sampling plan. • The model minimises the total metering cost and optimise the annual sample size during the crediting period. • The required 90/10 criterion sampling accuracy is satisfied for each CDM monitoring report. - Abstract: This paper proposes a metering cost minimisation model that minimises metering cost under the constraints of sampling accuracy requirement for clean development mechanism (CDM) energy efficiency (EE) lighting project. Usually small scale (SSC) CDM EE lighting projects expect a crediting period of 10 years given that the lighting population will decay as time goes by. The SSC CDM sampling guideline requires that the monitored key parameters for the carbon emission reduction quantification must satisfy the sampling accuracy of 90% confidence and 10% precision, known as the 90/10 criterion. For the existing registered CDM lighting projects, sample sizes are either decided by professional judgment or by rule-of-thumb without considering any optimisation. Lighting samples are randomly selected and their energy consumptions are monitored continuously by power meters. In this study, the sampling size determination problem is formulated as a metering cost minimisation model by incorporating a linear lighting decay model as given by the CDM guideline AMS-II.J. The 90/10 criterion is formulated as constraints to the metering cost minimisation problem. Optimal solutions to the problem minimise the metering cost whilst satisfying the 90/10 criterion for each reporting period. The proposed metering cost minimisation model is applicable to other CDM lighting projects with different population decay characteristics as well

  11. Optimization of automation: III. Development of optimization method for determining automation rate in nuclear power plants

    International Nuclear Information System (INIS)

    Lee, Seung Min; Kim, Jong Hyun; Kim, Man Cheol; Seong, Poong Hyun

    2016-01-01

    Highlights: • We propose an appropriate automation rate that enables the best human performance. • We analyze the shortest working time considering Situation Awareness Recovery (SAR). • The optimized automation rate is estimated by integrating the automation and ostracism rate estimation methods. • The process to derive the optimized automation rate is demonstrated through case studies. - Abstract: Automation has been introduced in various industries, including the nuclear field, because it is commonly believed that automation promises greater efficiency, lower workloads, and fewer operator errors through reducing operator errors and enhancing operator and system performance. However, the excessive introduction of automation has deteriorated operator performance due to the side effects of automation, which are referred to as Out-of-the-Loop (OOTL), and this is critical issue that must be resolved. Thus, in order to determine the optimal level of automation introduction that assures the best human operator performance, a quantitative method of optimizing the automation is proposed in this paper. In order to propose the optimization method for determining appropriate automation levels that enable the best human performance, the automation rate and ostracism rate, which are estimation methods that quantitatively analyze the positive and negative effects of automation, respectively, are integrated. The integration was conducted in order to derive the shortest working time through considering the concept of situation awareness recovery (SAR), which states that the automation rate with the shortest working time assures the best human performance. The process to derive the optimized automation rate is demonstrated through an emergency operation scenario-based case study. In this case study, four types of procedures are assumed through redesigning the original emergency operating procedure according to the introduced automation and ostracism levels. Using the

  12. Optimal purification and sensitive quantification of DNA from fecal samples

    DEFF Research Database (Denmark)

    Jensen, Annette Nygaard; Hoorfar, Jeffrey

    2002-01-01

    Application of reliable, rapid and sensitive methods to laboratory diagnosis of zoonotic infections continues to challenge microbiological laboratories. The recovery of DNA from a swine fecal sample and a bacterial culture extracted by a conventional phenol-chloroform extraction method was compared...... = 0.99 and R-2 = 1.00). In conclusion, silica-membrane, columns can provide a more convenient and less hazardous alternative to the conventional phenol-based method. The results have implication for further improvement of sensitive amplification methods for laboratory diagnosis....

  13. Determination of the stoichiometric ratio uranium dioxide samples

    International Nuclear Information System (INIS)

    Moura, Sergio Carvalho

    1999-01-01

    The determination of the O/U stoichiometric ratio in uranium dioxide is an important parameter in order to qualify nuclear fuels. The excess oxygen in the crystallographic structure can cause changes in the physico-chemical properties of this compound such as variation of the thermal conductivity alterations, fuel plasticity and others, affecting the efficiency of this material when it is utilized as nuclear fuel in the reactor core. The purpose of this work is to evaluate methods for the determination of uranium oxide samples from two different production processes, using gravimetric, voltammetric and X-ray diffraction techniques. After the evaluation of these techniques, the main aspect of this work is to define a reliable methodology in order to characterize the behavior of uranium oxide. The methodology used in this work consisted of two different steps: utilization of gravimetric and volumetric methods in order to determine the ratio in uranium dioxide samples; utilization of X-ray diffraction technique in order to determine the lattice parameters using patterns and application of the Rietveld method during refining of the structural data. As a result of the experimental part of this work it was found that the X-ray diffraction analysis performs better and detects the presence of more phases than gravimetric and voltammetric techniques, not sensitive enough in this detection. (author)

  14. An Indirect Simulation-Optimization Model for Determining Optimal TMDL Allocation under Uncertainty

    Directory of Open Access Journals (Sweden)

    Feng Zhou

    2015-11-01

    Full Text Available An indirect simulation-optimization model framework with enhanced computational efficiency and risk-based decision-making capability was developed to determine optimal total maximum daily load (TMDL allocation under uncertainty. To convert the traditional direct simulation-optimization model into our indirect equivalent model framework, we proposed a two-step strategy: (1 application of interval regression equations derived by a Bayesian recursive regression tree (BRRT v2 algorithm, which approximates the original hydrodynamic and water-quality simulation models and accurately quantifies the inherent nonlinear relationship between nutrient load reductions and the credible interval of algal biomass with a given confidence interval; and (2 incorporation of the calibrated interval regression equations into an uncertain optimization framework, which is further converted to our indirect equivalent framework by the enhanced-interval linear programming (EILP method and provides approximate-optimal solutions at various risk levels. The proposed strategy was applied to the Swift Creek Reservoir’s nutrient TMDL allocation (Chesterfield County, VA to identify the minimum nutrient load allocations required from eight sub-watersheds to ensure compliance with user-specified chlorophyll criteria. Our results indicated that the BRRT-EILP model could identify critical sub-watersheds faster than the traditional one and requires lower reduction of nutrient loadings compared to traditional stochastic simulation and trial-and-error (TAE approaches. This suggests that our proposed framework performs better in optimal TMDL development compared to the traditional simulation-optimization models and provides extreme and non-extreme tradeoff analysis under uncertainty for risk-based decision making.

  15. Determination of radiostrontium in soil samples using a crown ether

    Energy Technology Data Exchange (ETDEWEB)

    Vajda, N; Ghods-Esphahani, A; Danesi, P R [International Atomic Energy Agency, Agency' s Laboratories, Chemistry Unit, PCI Laboratory, Seibersdorf (Austria)

    1995-07-01

    A simple and rapid method has been developed for the separation and successive determination of total radiostrontium in soil. The method consists of three basic steps: oxalate precipitation to remove bulk potassium, chromatographic separation of strontium from most inactive and radioactive interferences utilizing a crown ether (Sr. Spec, EIChroM Industries, II. USA), oxalate precipitation of strontium to evaluate the chemical yield. Radiostrontium is then determined by liquid scintillation counting of the dissolved precipitate. When 10 g samples of soil are used the sensitivity of the method is about 10 Bq/kg. The chemical yield is about 80%. The separation and determination of radiostrontium can be carried out in about 8 hours. (author)

  16. Determination of radiostrontium in soil samples using a crown ether

    International Nuclear Information System (INIS)

    Vajda, N.; Ghods-Esphahani, A.; Danesi, P.R.

    1995-01-01

    A simple and rapid method has been developed for the separation and successive determination of total radiostrontium in soil. The method consists of three basic steps: oxalate precipitation to remove bulk potassium, chromatographic separation of strontium from most inactive and radioactive interferences utilizing a crown ether (Sr. Spec, EIChroM Industries, II. USA), oxalate precipitation of strontium to evaluate the chemical yield. Radiostrontium is then determined by liquid scintillation counting of the dissolved precipitate. When 10 g samples of soil are used the sensitivity of the method is about 10 Bq/kg. The chemical yield is about 80%. The separation and determination of radiostrontium can be carried out in about 8 hours. (author)

  17. Perturbing engine performance measurements to determine optimal engine control settings

    Science.gov (United States)

    Jiang, Li; Lee, Donghoon; Yilmaz, Hakan; Stefanopoulou, Anna

    2014-12-30

    Methods and systems for optimizing a performance of a vehicle engine are provided. The method includes determining an initial value for a first engine control parameter based on one or more detected operating conditions of the vehicle engine, determining a value of an engine performance variable, and artificially perturbing the determined value of the engine performance variable. The initial value for the first engine control parameter is then adjusted based on the perturbed engine performance variable causing the engine performance variable to approach a target engine performance variable. Operation of the vehicle engine is controlled based on the adjusted initial value for the first engine control parameter. These acts are repeated until the engine performance variable approaches the target engine performance variable.

  18. [Pretreatment of Aluminum-Lithium Alloy Sample and Determination of Argentum and Lithium by Spectral Analysis].

    Science.gov (United States)

    Zhou, Hui; Tan, Qian; Gao, Ya-ling; Sang, Shi-hua; Chen, Wen

    2015-10-01

    Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Flame Atomic Absorption Spectrometry (FAAS) and Visible Spectrometry (VS) was applied for determination of Ag and Li in lithium-aluminium alloy standard sample and test sample, their respective advantages and disadvantages were compared, the excellent selectivity of ICP-OES was confirmed by analyses of certified standard sample. Three different sample digestion methods were compared and discussed in this study. It was found that the better accuracy would be obtained by digesting sample with chloroazotic acid while the content of Li was measured by FAAS, and it was better to digest sample with hydrochloric acid and hydrogen peroxide while determining Ag and Li by ICP-OES simultaneously and determining Ag by FAAS and VS. The interference of co-existing elements and elimination methods was detailedly discussed. Ammonium hydroxide was added to adjust the sample solution into alkalescent and Al, Ti, Zr was precipitated by forming hydroxide precipitation, Mg and Cu was formed complex precipitation with 8-hydroxyquinoline in this condition, then the interference from matrix element to determinate Ag by FAAS was eliminated. In addition, phosphate was used to precipitate Ti to eliminate its interference for determination of Li by FAAS. The same treatment of determination for Ag by FAAS was used to eliminate the interference of matrix element for determination of Ag by VS, the excess of nitrate was added into sample and heated to release Ag+ from silver chloride complex, and the color of 8-hydroxyquinoline was eliminated because of decomposed by heating. The accuracy of analysis result for standard sample was conspicuously improved which confirms the efficient of the method to eliminate interference in this study. The optimal digestion method and eliminate interference method was applied to lithium-aluminium alloy samples. The recovery of samples was from 100.39% to 103.01% by ICP-OES determination for Ag

  19. Optical methods for microstructure determination of doped samples

    Science.gov (United States)

    Ciosek, Jerzy F.

    2008-12-01

    The optical methods to determine refractive index profile of layered materials are commonly used with spectroscopic ellipsometry or transmittance/reflectance spectrometry. Measurements of spectral reflection and transmission usually permit to characterize optical materials and determine their refractive index. However, it is possible to characterize of samples with dopants, impurities as well as defects using optical methods. Microstructures of a hydrogenated crystalline Si wafer and a layer of SiO2 - ZrO2 composition are investigated. The first sample is a Si(001):H Czochralski grown single crystalline wafer with 50 nm thick surface Si02 layer. Hydrogen dose implantation (D continue to be an important issue in microelectronic device and sensor fabrication. Hydrogen-implanted silicon (Si: H) has become a topic of remarkable interest, mostly because of the potential of implantation-induced platelets and micro-cavities for the creation of gettering -active areas and for Si layer splitting. Oxygen precipitation and atmospheric impurity are analysed. The second sample is the layer of co-evaporated SiO2 and ZrO2 materials using simultaneously two electron beam guns in reactive evaporation methods. The composition structure was investigated by X-Ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry methods. A non-uniformity and composition of layer are analysed using average density method.

  20. Determination of selenium in food matrices by replicate sample neutron activation analysis

    International Nuclear Information System (INIS)

    Ventura, M.G.; Freitas, M.C.; Ventura, M.G.; Pacheco, A.M.G.

    2009-01-01

    The replicate sample instrumental neutron activation method was optimized and used for the determination of selenium in foodstuffs. The method was reliable, yielding accurate results. Lower detections limits were obtained after each successive irradiation. Different irradiation conditions were used depending on the type of sample. For samples with higher selenium contents (meat, fish, eggs), the measured selenium in the first replicate is in all cases larger than the detection limit, but a better accuracy was obtained with a larger number of replicates (2-3 replicates). For samples with extremely low selenium contents (vegetable samples), at least seven replicates were necessary to obtain a concentration value two times larger than the detection limit. (author)

  1. Isotope determination of sulfur by mass spectrometry in soil samples

    Directory of Open Access Journals (Sweden)

    Alexssandra Luiza Rodrigues Molina Rossete

    2012-12-01

    Full Text Available Sulphur plays an essential role in plants and is one of the main nutrients in several metabolic processes. It has four stable isotopes (32S, 33S, 34S, and 36S with a natural abundance of 95.00, 0.76, 4.22, and 0.014 in atom %, respectively. A method for isotopic determination of S by isotope-ratio mass spectrometry (IRMS in soil samples is proposed. The procedure involves the oxidation of organic S to sulphate (S-SO4(2-, which was determined by dry combustion with alkaline oxidizing agents. The total S-SO4(2- concentration was determined by turbidimetry and the results showed that the conversion process was adequate. To produce gaseous SO2 gas, BaSO4 was thermally decomposed in a vacuum system at 900 ºC in the presence of NaPO3. The isotope determination of S (atom % 34S atoms was carried out by isotope ratio mass spectrometry (IRMS. In this work, the labeled material (K2(34SO4 was used to validate the method of isotopic determination of S; the results were precise and accurate, showing the viability of the proposed method.

  2. On-capillary sample cleanup method for the electrophoretic determination of carbohydrates in juice samples.

    Science.gov (United States)

    Morales-Cid, Gabriel; Simonet, Bartolomé M; Cárdenas, Soledad; Valcárcel, Miguel

    2007-05-01

    On many occasions, sample treatment is a critical step in electrophoretic analysis. As an alternative to batch procedures, in this work, a new strategy is presented with a view to develop an on-capillary sample cleanup method. This strategy is based on the partial filling of the capillary with carboxylated single-walled carbon nanotube (c-SWNT). The nanoparticles retain interferences from the matrix allowing the determination and quantification of carbohydrates (viz glucose, maltose and fructose). The precision of the method for the analysis of real samples ranged from 5.3 to 6.4%. The proposed method was compared with a method based on a batch filtration of the juice sample through diatomaceous earth and further electrophoretic determination. This method was also validated in this work. The RSD for this other method ranged from 5.1 to 6%. The results obtained by both methods were statistically comparable demonstrating the accuracy of the proposed methods and their effectiveness. Electrophoretic separation of carbohydrates was achieved using 200 mM borate solution as a buffer at pH 9.5 and applying 15 kV. During separation, the capillary temperature was kept constant at 40 degrees C. For the on-capillary cleanup method, a solution containing 50 mg/L of c-SWNTs prepared in 300 mM borate solution at pH 9.5 was introduced for 60 s into the capillary just before sample introduction. For the electrophoretic analysis of samples cleaned in batch with diatomaceous earth, it is also recommended to introduce into the capillary, just before the sample, a 300 mM borate solution as it enhances the sensitivity and electrophoretic resolution.

  3. Portable tester for determining gas content within a core sample

    Science.gov (United States)

    Garcia, F. Jr.; Schatzel, S.J.

    1998-04-21

    A portable tester is provided for reading and displaying the pressure of a gas released from a rock core sample stored within a sealed container and for taking a sample of the released pressurized gas for chemical analysis thereof for subsequent use in a modified direct method test which determines the volume of gas and specific type of gas contained within the core sample. The portable tester includes a pair of low and high range electrical pressure transducers for detecting a gas pressure; a pair of low and high range display units for displaying the pressure of the detected gas; a selector valve connected to the low and high range pressure transducers and a selector knob for selecting gas flow to one of the flow paths; control valve having an inlet connection to the sealed container; and outlets connected to: a sample gas canister, a second outlet port connected to the selector valve means for reading the pressure of the gas from the sealed container to either the low range or high range pressure transducers, and a connection for venting gas contained within the sealed container to the atmosphere. A battery is electrically connected to and supplies the power for operating the unit. The pressure transducers, display units, selector and control valve means and the battery is mounted to and housed within a protective casing for portable transport and use. 5 figs.

  4. Determining photon energy absorption parameters for different soil samples

    International Nuclear Information System (INIS)

    Kucuk, Nil; Cakir, Merve; Tumsavas, Zeynal

    2013-01-01

    The mass attenuation coefficients (μ s ) for five different soil samples were measured at 661.6, 1173.2 and 1332.5 keV photon energies. The soil samples were separately irradiated with 137 Cs and 60 Co (370 kBq) radioactive point gamma sources. The measurements were made by performing transmission experiments with a 2″ x 2″ NaI(Tl) scintillation detector, which had an energy resolution of 7% at 0.662 MeV for the gamma-rays from the decay of 137 Cs. The effective atomic numbers (Z eff ) and the effective electron densities (N eff ) were determined experimentally and theoretically using the obtained μ s values for the soil samples. Furthermore, the Z eff and N eff values of the soil samples were computed for the total photon interaction cross-sections using theoretical data over a wide energy region ranging from 1 keV to 15 MeV. The experimental values of the soils were found to be in good agreement with the theoretical values. Sandy loam and sandy clay loam soils demonstrated poor photon energy absorption characteristics. However, clay loam and clay soils had good photon energy absorption characteristics. (author)

  5. Determination of uranium in samples containing bulk aluminium

    International Nuclear Information System (INIS)

    Das, S.K.; Kannan, R.; Dhami, P.S.; Tripathi, S.C.; Gandhi, P.M.

    2015-01-01

    The determination of uranium is of great importance in PUREX process and need to be analyzed at different concentration ranges depending on the stage of reprocessing. Various techniques like volumetry, spectrophotometry, ICP-OES, fluorimetry, mass spectrometry etc. are used for the measurement of uranium in these samples. Fast and sensitive methods suitable for low level detection of uranium are desirable to cater the process needs. Microgram quantities of uranium are analyzed by spectrophotometric method using 2-(5- bromo-2-pyridylazo-5-diethylaminophenol) (Br-PADAP) as the complexing agent. But, the presence of some of the metal ions viz. Al, Pu, Zr etc. interferes in its analysis. Therefore, separation of uranium from such interfering metal ions is required prior to its analysis. This paper describes the analysis of uranium in samples containing aluminium as major matrix

  6. Solid-phase extraction and determination of trace elements in environmental samples using naphthalene adsorbent

    International Nuclear Information System (INIS)

    Pourreza, N.

    2004-01-01

    Naphthalene co-precipitated with quaternary ammonium salt such as tetraoctyl ammonium bromide and methyltrioctyl ammonium chloride have been used as adsorbent for solid phase extraction of metal ions such as Hg, Cd and Fe. The metal ions are retained on the adsorbent in a column as their complexes with suitable ligands and eluted by an eluent before instrumental measurements. The optimization of the procedures for solid phase extraction and consequent determination of trace elements and application to environmental samples especially water samples will be discussed. (author)

  7. Neutron activation analysis for the optimal sampling and extraction of extractable organohalogens in human hari

    International Nuclear Information System (INIS)

    Zhang, H.; Chai, Z.F.; Sun, H.B.; Xu, H.F.

    2005-01-01

    Many persistent organohalogen compounds such as DDTs and polychlorinated biphenyls have caused seriously environmental pollution problem that now involves all life. It is know that neutron activation analysis (NAA) is a very convenient method for halogen analysis and is also the only method currently available for simultaneously determining organic chlorine, bromine and iodine in one extract. Human hair is a convenient material to evaluate the burden of such compounds in human body and dan be easily collected from people over wide ranges of age, sex, residential areas, eating habits and working environments. To effectively extract organohalogen compounds from human hair, in present work the optimal Soxhelt-extraction time of extractable organohalogen (EOX) and extractable persistent organohalogen (EPOX) from hair of different lengths were studied by NAA. The results indicated that the optimal Soxhelt-extraction time of EOX and EPOX from human hair was 8-11 h, and the highest EOX and EPOX contents were observed in hair powder extract. The concentrations of both EOX and EPOX in different hair sections were in the order of hair powder ≥ 2 mm > 5 mm, which stated that hair samples milled into hair powder or cut into very short sections were not only for homogeneous. hair sample but for the best hair extraction efficiency.

  8. Critical evaluation of distillation procedure for the determination of methylmercury in soil samples.

    Science.gov (United States)

    Perez, Pablo A; Hintelman, Holger; Quiroz, Waldo; Bravo, Manuel A

    2017-11-01

    In the present work, the efficiency of distillation process for extracting monomethylmercury (MMHg) from soil samples was studied and optimized using an experimental design methodology. The influence of soil composition on MMHg extraction was evaluated by testing of four soil samples with different geochemical characteristics. Optimization suggested that the acid concentration and the duration of the distillation process were most significant and the most favorable conditions, established as a compromise for the studied soils, were determined to be a 70 min distillation using an 0.2 M acid. Corresponding limits of detection (LOD) and quantification (LOQ) were 0.21 and 0.7 pg absolute, respectively. The optimized methodology was applied with satisfactory results to soil samples and was compared to a reference methodology based on isotopic dilution analysis followed by gas chromatography-inductively coupled plasma mass spectrometry (IDA-GC-ICP-MS). Using the optimized conditions, recoveries ranged from 82 to 98%, which is an increase of 9-34% relative to the previously used standard operating procedure. Finally, the validated methodology was applied to quantify MMHg in soils collected from different sites impacted by coal fired power plants in the north-central zone of Chile, measuring MMHg concentrations ranging from 0.091 to 2.8 ng g -1 . These data are to the best of our knowledge the first MMHg measurements reported for Chile. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. A Sequential Optimization Sampling Method for Metamodels with Radial Basis Functions

    Science.gov (United States)

    Pan, Guang; Ye, Pengcheng; Yang, Zhidong

    2014-01-01

    Metamodels have been widely used in engineering design to facilitate analysis and optimization of complex systems that involve computationally expensive simulation programs. The accuracy of metamodels is strongly affected by the sampling methods. In this paper, a new sequential optimization sampling method is proposed. Based on the new sampling method, metamodels can be constructed repeatedly through the addition of sampling points, namely, extrema points of metamodels and minimum points of density function. Afterwards, the more accurate metamodels would be constructed by the procedure above. The validity and effectiveness of proposed sampling method are examined by studying typical numerical examples. PMID:25133206

  10. Spectrographic determination of impurities in ammonium hydrogen fluoride samples

    International Nuclear Information System (INIS)

    Roca, M.; Capdevila, C.; Alduan, F.A.

    1976-01-01

    The quantitative spectrographic trace determination of Al, B, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Si in ammonium hydrogen fluoride samples is considered. 10 A dc arc excitation and graphite electrodes with crate either 4.5 mm or 8 mm deep are employed. A comparison of various matrices such as graphite, gallium oxide, germanium oxide, magnesium oxide and zinc oxide, in the ratios 1:1 and 1:3, as well as a mixture 50% graphite - 50% zinc oxide in the ratio 1:1 is included. Zinc oxide in the ratio 1:1 and 4x8 mm craters show the best over-all results. (author)

  11. Determination of strontium-90 in the environmental samples at PINSTECH

    International Nuclear Information System (INIS)

    Perveen, N.; Aziz, A.

    1979-01-01

    Strontium-90 a bone seeking radionuclide and a long lived beta emitter is one of the toxic radionuclides detected in the environment arising mainly from the fall out from nuclear detonations. Its concentration in various environmental media such as air, precipitation, surface water, vegetables and other items of diet was measured. This report describes the method of collection, treatment and radiochemical analyses of environmental samples for the determination of Sr-90. The levels of Sr-90 concentration in these media are also recorded. (authors)

  12. Determination of palladium in biological samples applying nuclear analytical techniques

    International Nuclear Information System (INIS)

    Cavalcante, Cassio Q.; Sato, Ivone M.; Salvador, Vera L. R.; Saiki, Mitiko

    2008-01-01

    This study presents Pd determinations in bovine tissue samples containing palladium prepared in the laboratory, and CCQM-P63 automotive catalyst materials of the Proficiency Test, using instrumental thermal and epithermal neutron activation analysis and energy dispersive X-ray fluorescence techniques. Solvent extraction and solid phase extraction procedures were also applied to separate Pd from interfering elements before the irradiation in the nuclear reactor. The results obtained by different techniques were compared against each other to examine sensitivity, precision and accuracy. (author)

  13. A simple optimized microwave digestion method for multielement monitoring in mussel samples

    International Nuclear Information System (INIS)

    Saavedra, Y.; Gonzalez, A.; Fernandez, P.; Blanco, J.

    2004-01-01

    With the aim of obtaining a set of common decomposition conditions allowing the determination of several metals in mussel tissue (Hg by cold vapour atomic absorption spectrometry; Cu and Zn by flame atomic absorption spectrometry; and Cd, PbCr, Ni, As and Ag by electrothermal atomic absorption spectrometry), a factorial experiment was carried out using as factors the sample weight, digestion time and acid addition. It was found that the optimal conditions were 0.5 g of freeze-dried and triturated samples with 6 ml of nitric acid and subjected to microwave heating for 20 min at 180 psi. This pre-treatment, using only one step and one oxidative reagent, was suitable to determine the nine metals studied with no subsequent handling of the digest. It was possible to carry out the determination of atomic absorption using calibrations with aqueous standards and matrix modifiers for cadmium, lead, chromium, arsenic and silver. The accuracy of the procedure was checked using oyster tissue (SRM 1566b) and mussel tissue (CRM 278R) certified reference materials. The method is now used routinely to monitor these metals in wild and cultivated mussels, and found to be good

  14. Determination of optimal conditions of oxytetracyclin production from streptomyces rimosus

    International Nuclear Information System (INIS)

    Zouaghi, Atef

    2007-01-01

    Streptomyces rimosus is an oxytetracycline (OTC) antibiotic producing bacteria that exhibited activities against gram positive and negative bacteria. OTC is used widely not only in medicine but also in production industry. The antibiotic production of streptomyces covers a very wide range of condition. However, antibiotic producers are particularly fastidious cultivated by proper selection of media such as carbon source. In present study we have optimised conditions of OTC production (Composition of production media, p H, shaking and temperature). The results have been shown that bran barley is the optimal media for OTC production at 28C pH5.8 at 150rpm for 5 days. For antibiotic determination, OTC was extracted with different organic solvent. Thin-layer chromatography system was used for separation and identification of OTC antibiotic. High performance liquid chromatographic (HPLC) method with ultraviolet detection for the analysis of OTC is applied to the determination of OTC purification. (Author). 24 refs

  15. Population pharmacokinetic analysis of clopidogrel in healthy Jordanian subjects with emphasis optimal sampling strategy.

    Science.gov (United States)

    Yousef, A M; Melhem, M; Xue, B; Arafat, T; Reynolds, D K; Van Wart, S A

    2013-05-01

    Clopidogrel is metabolized primarily into an inactive carboxyl metabolite (clopidogrel-IM) or to a lesser extent an active thiol metabolite. A population pharmacokinetic (PK) model was developed using NONMEM(®) to describe the time course of clopidogrel-IM in plasma and to design a sparse-sampling strategy to predict clopidogrel-IM exposures for use in characterizing anti-platelet activity. Serial blood samples from 76 healthy Jordanian subjects administered a single 75 mg oral dose of clopidogrel were collected and assayed for clopidogrel-IM using reverse phase high performance liquid chromatography. A two-compartment (2-CMT) PK model with first-order absorption and elimination plus an absorption lag-time was evaluated, as well as a variation of this model designed to mimic enterohepatic recycling (EHC). Optimal PK sampling strategies (OSS) were determined using WinPOPT based upon collection of 3-12 post-dose samples. A two-compartment model with EHC provided the best fit and reduced bias in C(max) (median prediction error (PE%) of 9.58% versus 12.2%) relative to the basic two-compartment model, AUC(0-24) was similar for both models (median PE% = 1.39%). The OSS for fitting the two-compartment model with EHC required the collection of seven samples (0.25, 1, 2, 4, 5, 6 and 12 h). Reasonably unbiased and precise exposures were obtained when re-fitting this model to a reduced dataset considering only these sampling times. A two-compartment model considering EHC best characterized the time course of clopidogrel-IM in plasma. Use of the suggested OSS will allow for the collection of fewer PK samples when assessing clopidogrel-IM exposures. Copyright © 2013 John Wiley & Sons, Ltd.

  16. The use of slurry sampling for the determination of manganese and copper in various samples by electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Tokman, Nilgun

    2007-01-01

    Manganese and copper in multivitamin-mineral supplements and standard reference materials were determined by slurry sampling electrothermal atomic absorption spectrometry. Slurries were prepared in an aqueous solution containing Triton X-100. The effects of different parameters such as ratio of solid to liquid phase volume, total slurry volume and addition of Triton X-100 as a dispersant on the analytical results were investigated. The graphite furnace programs were optimized for slurry sampling depending on the analytes and their concentrations in the samples. The linear calibration method with aqueous standard solutions was used for the quantification. At optimum experimental conditions, R.S.D. values were below 5%. The analytes were determined in the limits of 95% confidence level with respect to certified values in coal and soil standard reference materials and to those found by wet-digestion in multivitamin-mineral supplements. Detection limits (3δ) for Mn and Cu were 0.10 μg L -1 and 1.82 μg L -1 for 10 μL coal standard reference material slurry, respectively

  17. A hybrid reliability algorithm using PSO-optimized Kriging model and adaptive importance sampling

    Science.gov (United States)

    Tong, Cao; Gong, Haili

    2018-03-01

    This paper aims to reduce the computational cost of reliability analysis. A new hybrid algorithm is proposed based on PSO-optimized Kriging model and adaptive importance sampling method. Firstly, the particle swarm optimization algorithm (PSO) is used to optimize the parameters of Kriging model. A typical function is fitted to validate improvement by comparing results of PSO-optimized Kriging model with those of the original Kriging model. Secondly, a hybrid algorithm for reliability analysis combined optimized Kriging model and adaptive importance sampling is proposed. Two cases from literatures are given to validate the efficiency and correctness. The proposed method is proved to be more efficient due to its application of small number of sample points according to comparison results.

  18. Determination of some trace elements in biological samples using XRF and TXRF techniques

    International Nuclear Information System (INIS)

    Khuder, A.; Karjou, J.; Sawan, M. K.

    2006-07-01

    XRF and TXRF techniques were successfully used for the multi-element determination of trace elements in whole blood and human head hair samples. This was achieved by the direct analysis using XRF technique with different collimation units and by the optimized chemical procedures for TXRF analysis. Light element of S and P were preferably determined by XRF with primary x-ray excitation, while, elements of K, Ca, Fe, and Br were determined with a very good accuracy and precision using XRF with Cu- and Mo-secondary targets. The chemical procedure dependent on the preconcentration of trace elements by APDC was superiorly used for the determination of traces of Ni and Pb in the range of 1.0-1.7 μg/dl and 11-23 μg/dl, respectively, in whole blood samples by TXRF technique; determination of other elements as Cu and Zn was also achievable using this approach. Rb in whole blood samples was determined directly after the digestion of samples using PTFE-bomb for TXRF analysis. (author)

  19. Determination of sampling constants for selenium by cyclic INAA

    International Nuclear Information System (INIS)

    Chatt, A.; Jayawickreme, C.K.

    1988-01-01

    Biological reference materials of natural origin and certified elemental composition play an important role in not only evaluating the reliability of a new method but also assuring the quality of data produced in routine analysis. In fact, it has become a common practice to include an appropriate certified reference material (CRM) in every batch of samples analyzed for the purpose of quality assurance. One of the most important properties of a CRM or reference material (RM) should be its degree of homogeneity. For biological materials, inhomogeneity is inherently associated with their intricate structures. In order to justify the usage of a CRM or RM at a mass lower than that recommended by the issuing agency, is necessary to evaluate the homogeneity at lower mass ranges and to determine the sampling constant for the element of interest. The objectives of the present work are to investigate the homogeneity and to calculate the sampling constants for selenium in several biological CRM and RM that are frequently used to evaluate the accuracy of measurements

  20. Analytical methodologies for the determination of benzodiazepines in biological samples.

    Science.gov (United States)

    Persona, Karolina; Madej, Katarzyna; Knihnicki, Paweł; Piekoszewski, Wojciech

    2015-09-10

    Benzodiazepine drugs belong to important and most widely used medicaments. They demonstrate such therapeutic properties as anxiolytic, sedative, somnifacient, anticonvulsant, diastolic and muscle relaxant effects. However, despite the fact that benzodiazepines possess high therapeutic index and are considered to be relatively safe, their use can be dangerous when: (1) co-administered with alcohol, (2) co-administered with other medicaments like sedatives, antidepressants, neuroleptics or morphine like substances, (3) driving under their influence, (4) using benzodiazepines non-therapeutically as drugs of abuse or in drug-facilitated crimes. For these reasons benzodiazepines are still studied and determined in a variety of biological materials. In this article, sample preparation techniques which have been applied in analysis of benzodiazepine drugs in biological samples have been reviewed and presented. The next part of the article is focused on a review of analytical methods which have been employed for pharmacological, toxicological or forensic study of this group of drugs in the biological matrices. The review was preceded by a description of the physicochemical properties of the selected benzodiazepines and two, very often coexisting in the same analyzed samples, sedative-hypnotic drugs. Copyright © 2015. Published by Elsevier B.V.

  1. Micellar electrokinetic chromatographic determination of triazine herbicides in water samples.

    Science.gov (United States)

    Li, Zhi; Zhang, Shuaihua; Yin, Xiaofang; Wang, Chun; Wang, Zhi

    2014-09-01

    Dispersive liquid-liquid microextraction combined with online sweeping preconcentration in micellar electrokinetic chromatography was developed for the simultaneous determination of five triazine herbicides (atrazine, simazine, propazine, prometon and simetryn) in water samples. Several experimental parameters affecting the extraction efficiencies such as the type and volume of both the extraction and dispersive solvents, the addition of salt to sample solution, the extraction time and the pH of the sample solution were investigated. Under optimum conditions, the linearity of the method was good in the range from 0.33 to 20 ng mL(-1) for simazine, propazine, atrazine and simetryn, and from 0.17 to 20 ng mL(-1) for prometon, respectively. The sensitivity enrichment factors were in the range from 1750 to 2100, depending on the compound. The limit of detection (S/N = 3) ranged from 0.05 to 0.10 ng mL(-1). The developed method was successfully applied to the analysis of the five triazines in river, ground and well waters. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Quantitative determination of 210Po in geochemical samples

    International Nuclear Information System (INIS)

    Dyck, W.; Bristow, Q.

    1984-01-01

    To test the usefulness of 210 Po in soils as a means of detecting buried U mineralization, methods for the determination of 210 Po were investigated and adapted for routine production of 210 Po data from geochemical samples. A number of conditions affecting autodeposition and detection of 210 Po were investigated. The optimum area of deposition with a 450 mm 2 solid state detector was found to be 300 mm 2 . Convenience dictated room temperature over-night deposition times, although increased temperature increased speed and efficiency of deposition. A clear inverse relationship was observed between volume of solution and deposition efficiency with stirring times of less than 2 hours. For routine analysis, soil and rock powders were dissolved by leaching 1 g samples in teflon beakers successively with conc. HNO 3 , HF, and HNO 3 -HClO 4 , evaporating the solution to dryness between leaches, and taking the residue up in 20 mL 0.5 M HCl. The 210 Po was deposited on 19 mm diameter Ni discs and counted with an alpha spectrometer system employing 450 mm 2 ruggedized surface barrier detectors. The method achieved 90 percent recovery of 210 Po from solution and a detection efficiency of 30 percent. With a counting time of 3 hours, the method is capable of detecting 0.2 pCi of 210 Po per gram of sample

  3. Optimization of experimental conditions in uranium trace determination using laser time-resolved fluorimetry

    International Nuclear Information System (INIS)

    Baly, L.; Garcia, M.A.

    1996-01-01

    At the present paper a new sample excitation geometry is presented for the uranium trace determination in aqueous solutions by the Time-Resolved Laser-Induced Fluorescence. This new design introduces the laser radiation through the top side of the cell allowing the use of cells with two quartz sides, less expensive than commonly used at this experimental set. Optimization of the excitation conditions, temporal discrimination and spectral selection are presented

  4. Heuristic Optimization Techniques for Determining Optimal Reserve Structure of Power Generating Systems

    DEFF Research Database (Denmark)

    Ding, Yi; Goel, Lalit; Wang, Peng

    2012-01-01

    cost of the system will also increase. The reserve structure of a MSS should be determined based on striking a balance between the required reliability and the reserve cost. The objective of reserve management for a MSS is to schedule the reserve at the minimum system reserve cost while maintaining......Electric power generating systems are typical examples of multi-state systems (MSS). Sufficient reserve is critically important for maintaining generating system reliabilities. The reliability of a system can be increased by increasing the reserve capacity, noting that at the same time the reserve...... the required level of supply reliability to its customers. In previous research, Genetic Algorithm (GA) has been used to solve most reliability optimization problems. However, the GA is not very computationally efficient in some cases. In this chapter a new heuristic optimization technique—the particle swarm...

  5. The State Fiscal Policy: Determinants and Optimization of Financial Flows

    Directory of Open Access Journals (Sweden)

    Sitash Tetiana D.

    2017-03-01

    Full Text Available The article outlines the determinants of the state fiscal policy at the present stage of global transformations. Using the principles of financial science it is determined that regulation of financial flows within the fiscal sphere, namely centralization and redistribution of the GDP, which results in the regulation of the financial capacity of economic agents, is of importance. It is emphasized that the urgent measure for improving the tax model is re-considering the provision of fiscal incentives, which are used to stimulate the accumulation of capital, investment activity, innovation, increase of the competitiveness of national products, expansion of exports, increase of the level of the population employment. The necessity of applying the instruments of fiscal regulation of financial flows, which should take place on the basis of institutional economics emphasizing the analysis of institutional changes, the evolution of institutions and their impact on the behavior of participants of economic relations. At the same time it is determined that the maximum effect of fiscal regulation of financial flows is ensured when application of fiscal instruments is aimed not only at achieving the target values of parameters of financial flows but at overcoming institutional deformations as well. It is determined that the optimal movement of financial flows enables creating favorable conditions for development and maintenance of financial balance in the society and achievement of the necessary level of competitiveness of the national economy.

  6. Determination of technetium-99 in environmental and radioactive waste samples

    International Nuclear Information System (INIS)

    Ferencova, M.; Peter Tkac, P.

    2007-01-01

    Technetium is known for its high mobility in a soil-water system in non-reducing aerobic condition and also high bio-availability for plants, because the most stable form of technetium in natural surface environment is pertechnetate which is highly soluble. The chemical form of technetium changes with environmental conditions. Concentration of technetium in the environment is very low, therefore many separation steps are needed for technetium determination. It has been developed a method for the routine determination of technetium-99 from environmental matrices and radioactive wastes using technetium-99m as an internal yield monitor. Technetium-99 is extracted from the soil samples with nitric acid. Many contaminants are co-precipitated with ferric hydroxide and technetium in the supernatant is pre-concentrated and further purified using anion exchange chromatography. Final separation of technetium was achieved by extraction with tetraphenylarsonium chloride in chloroform from sulphuric acid or pure water. The chemical yield is determined through the measurement of technetium-99m by scintillation counting system and the technetium-99 activity is measured using proportional counter after decay of the technetium-99m activity. Typical recoveries for this method are in the order 50-60 % (authors)

  7. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    Energy Technology Data Exchange (ETDEWEB)

    Zarepisheh, M; Li, R; Xing, L [Stanford UniversitySchool of Medicine, Stanford, CA (United States); Ye, Y [Stanford Univ, Management Science and Engineering, Stanford, Ca (United States); Boyd, S [Stanford University, Electrical Engineering, Stanford, CA (United States)

    2014-06-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  8. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    International Nuclear Information System (INIS)

    Zarepisheh, M; Li, R; Xing, L; Ye, Y; Boyd, S

    2014-01-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  9. Evaluation of active sampling strategies for the determination of 1,3-butadiene in air

    Science.gov (United States)

    Vallecillos, Laura; Maceira, Alba; Marcé, Rosa Maria; Borrull, Francesc

    2018-03-01

    Two analytical methods for determining levels of 1,3-butadiene in urban and industrial atmospheres were evaluated in this study. Both methods are extensively used for determining the concentration of volatile organic compounds in the atmosphere and involve collecting samples by active adsorptive enrichment on solid sorbents. The first method uses activated charcoal as the sorbent and involves liquid desorption with carbon disulfide. The second involves the use of a multi-sorbent bed with two graphitised carbons and a carbon molecular sieve as the sorbent, with thermal desorption. Special attention was paid to the optimization of the sampling procedure through the study of sample volume, the stability of 1,3-butadiene once inside the sampling tube and the humidity effect. In the end, the thermal desorption method showed better repeatability and limits of detection and quantification for 1,3-butadiene than the liquid desorption method, which makes the thermal desorption method more suitable for analysing air samples from both industrial and urban atmospheres. However, sampling must be performed with a pre-tube filled with a drying agent to prevent the loss of the adsorption capacity of the solid adsorbent caused by water vapour. The thermal desorption method has successfully been applied to determine of 1,3-butadiene inside a 1,3-butadiene production plant and at three locations in the vicinity of the same plant.

  10. Optimizing the triple-axis spectrometer PANDA at the MLZ for small samples and complex sample environment conditions

    Science.gov (United States)

    Utschick, C.; Skoulatos, M.; Schneidewind, A.; Böni, P.

    2016-11-01

    The cold-neutron triple-axis spectrometer PANDA at the neutron source FRM II has been serving an international user community studying condensed matter physics problems. We report on a new setup, improving the signal-to-noise ratio for small samples and pressure cell setups. Analytical and numerical Monte Carlo methods are used for the optimization of elliptic and parabolic focusing guides. They are placed between the monochromator and sample positions, and the flux at the sample is compared to the one achieved by standard monochromator focusing techniques. A 25 times smaller spot size is achieved, associated with a factor of 2 increased intensity, within the same divergence limits, ± 2 ° . This optional neutron focusing guide shall establish a top-class spectrometer for studying novel exotic properties of matter in combination with more stringent sample environment conditions such as extreme pressures associated with small sample sizes.

  11. Development of a fast capillary electrophoresis method for determination of carbohydrates in honey samples.

    Science.gov (United States)

    Rizelio, Viviane Maria; Tenfen, Laura; da Silveira, Roberta; Gonzaga, Luciano Valdemiro; Costa, Ana Carolina Oliveira; Fett, Roseane

    2012-05-15

    In this study, the determination of fructose, glucose and sucrose by capillary electrophoresis (CE) was investigated. The tendency of the analyte to undergo electromigration dispersion and the buffer capacity were evaluated using the Peakmaster(®) software and considered in the optimization of the background electrolyte, which was composed of 20 mmol L(-1) sorbic acid, 0.2 mmol L(-1) CTAB and 40 mmol L(-1) NaOH at pH 12.2. Under optimal CE conditions, the separation of the substances investigated was achieved in less than 2 min. The detection limits for the three analytes were in the range of 0.022 and 0.029 g L(-1) and precision measurements within 0.62-4.69% were achieved. The proposed methodology was applied in the quantitative analysis by direct injection of in honey samples to determine the main sugars presents. The samples were previously dissolved in deionized water and filtered with no other sample treatment. The mean values for fructose, glucose and sucrose were in the ranges of 33.65-45.46 g 100g(-1), 24.63-35.06 g 100g(-1) and <0.22-1.32 g 100g(-1), respectively. The good analytical performance of the method makes it suitable for implementation in food laboratories for the routine analysis of honey samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. The determination of arsenic, selenium, antimony, and tin in complex environmental samples by hydride generation AAS

    International Nuclear Information System (INIS)

    Johnson, D.; Beach, C.

    1990-01-01

    Hydride generation techniques are used routinely for the determination of As, Se, Sb and Sn in water samples. Advantages include high sensitivity, simplicity, and relative freedom from interferences. Continuous-flow designs greatly reduce analysis time as well as improve precision and allow for automation. However the accurate analysis of more complex environmental samples such as industrial sludges, soil samples, river sediments, and fly ash remains difficult. Numerous contributing factors influence the accuracy of the hydride technique. Sample digestion methods and sample preparation procedures are of critical importance. The digestion must adequately solubilize the elements of interest without loss by volatilization. Sample preparation procedures that guarantee the proper analyte oxidation state and eliminate the nitric acid and inter-element interferences are needed. In this study, difficult environmental samples were analyzed for As, Se, Sb, and Sn by continuous flow hydride generation. Sample preparation methods were optimized to eliminate interferences. The results of spike recovery studies will be presented. Data from the analysis of the same samples by graphite furnace AAS will be presented for comparison of accuracy, precision, and analysis time

  13. Determining of the Optimal Device Lifetime using Mathematical Renewal Models

    Directory of Open Access Journals (Sweden)

    Knežo Dušan

    2016-05-01

    Full Text Available Paper deals with the operations and equipment of the machine in the process of organizing production. During operation machines require maintenance and repairs, while in case of failure or machine wears it is necessary to replace them with new ones. For the process of replacement of old machines with new ones the term renewal is used. Qualitative aspects of the renewal process observe renewal theory, which is mainly based on the theory of probability and mathematical statistics. Devices lifetimes are closely related to the renewal of the devices. Presented article is focused on mathematical deduction of mathematical renewal models and determining optimal lifetime of the devices from the aspect of expenditures on renewal process.

  14. Determination of natural radionuclides in lichen samples of Carnoparmelia Texana

    International Nuclear Information System (INIS)

    Alencar, Marcos M.; Damatto, Sandra R.; Mazzilli, Barbara P.

    2009-01-01

    Lichen plays an important role in studies of environmental pollution. It can be used for the evaluation of air contaminants, including heavy metals and radionuclides. The main objective of this study is to verify the possibility of using the lichen species Canoparmelia Texana for the assessment of natural radionuclides of the U and Th decay series in air in the vicinity of Instituto de Pesquisas Energeticas e Nucleares (IPEN) installations. IPEN has as major activity to perform research in the field of the nuclear fuel cycle, and therefore deals with natural radionuclides of the U and Th series. The content of 238 U, 234 U, 230 Th, 210 Po and 232 Th in lichen samples were determined by alpha spectrometry after a radiochemical separation. Ra isotopes and 210 Pb were determined by gross alpha and beta counting after a radiochemical separation and measurement on a low background gas flow proportional detector. The results obtained for 238 U varied from 2.4 ± 0.4 Bq kg -1 to 6.6 ± 0.1 Bq kg -1 and from 4.4 ± 0.3 Bq kg -1 to 12.1 ± 2.6 Bq kg -1 , for 232 Th. For 226 Ra varied from 13 ± 1 Bq kg -1 to 38 ± 2 Bq kg -1 and from 200 ± 13 Bq kg -1 to 351 ± 12 Bqkg -1 for 228 Ra. The results obtained were compared with data obtained for the same radionuclides in lichen samples in an area affected by TENORM industry and can be considered as background for this lichen species. It can be concluded that the control of atmospheric discharges of IPEN facilities has been effective along the years, giving no evidence of radiological environmental impact. (author)

  15. Evaluation of optimized bronchoalveolar lavage sampling designs for characterization of pulmonary drug distribution.

    Science.gov (United States)

    Clewe, Oskar; Karlsson, Mats O; Simonsson, Ulrika S H

    2015-12-01

    Bronchoalveolar lavage (BAL) is a pulmonary sampling technique for characterization of drug concentrations in epithelial lining fluid and alveolar cells. Two hypothetical drugs with different pulmonary distribution rates (fast and slow) were considered. An optimized BAL sampling design was generated assuming no previous information regarding the pulmonary distribution (rate and extent) and with a maximum of two samples per subject. Simulations were performed to evaluate the impact of the number of samples per subject (1 or 2) and the sample size on the relative bias and relative root mean square error of the parameter estimates (rate and extent of pulmonary distribution). The optimized BAL sampling design depends on a characterized plasma concentration time profile, a population plasma pharmacokinetic model, the limit of quantification (LOQ) of the BAL method and involves only two BAL sample time points, one early and one late. The early sample should be taken as early as possible, where concentrations in the BAL fluid ≥ LOQ. The second sample should be taken at a time point in the declining part of the plasma curve, where the plasma concentration is equivalent to the plasma concentration in the early sample. Using a previously described general pulmonary distribution model linked to a plasma population pharmacokinetic model, simulated data using the final BAL sampling design enabled characterization of both the rate and extent of pulmonary distribution. The optimized BAL sampling design enables characterization of both the rate and extent of the pulmonary distribution for both fast and slowly equilibrating drugs.

  16. Determination of trihalomethanes in water samples: A review

    Energy Technology Data Exchange (ETDEWEB)

    Perez Pavon, Jose Luis [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias Quimicas, Universidad de Salamanca, 37008 Salamanca (Spain)], E-mail: jlpp@usal.es; Herrero Martin, Sara; Garcia Pinto, Carmelo; Moreno Cordero, Bernardo [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias Quimicas, Universidad de Salamanca, 37008 Salamanca (Spain)

    2008-11-23

    This article reviews the most recent literature addressing the analytical methods applied for trihalomethanes (THMs) determination in water samples. This analysis is usually performed with gas chromatography (GC) combined with a preconcentration step. The detectors most widely used in this type of analyses are mass spectrometers (MS) and electron capture detectors (ECD). Here, we review the analytical characteristics, the time required for analysis, and the simplicity of the optimised methods. The main difference between these methods lies in the sample pretreatment step; therefore, special emphasis is placed on this aspect. The techniques covered are direct aqueous injection (DAI), liquid-liquid extraction (LLE), headspace (HS), and membrane-based techniques. We also review the main chromatographic columns employed and consider novel aspects of chromatographic analysis, such as the use of fast gas chromatography (FGC). Concerning the detection step, besides the common techniques, the use of uncommon detectors such as fluorescence detector, pulsed discharge photoionization detector (PDPID), dry electrolytic conductivity detector (DELCD), atomic emission detector (AED) and inductively coupled plasma-mass spectrometry (ICP-MS) for this type of analysis is described.

  17. Determination of 241Am and 244Cm in environmental samples

    International Nuclear Information System (INIS)

    Bonino, N.O.; Grinman, A.D.R.; Serdeiro, N.H.

    1998-01-01

    The present technique describes a method to separate, purify and measure low levels of americium and curium in different environmental samples such as sediments, soils, water, vegetables, and air filters. The determination of radionuclides in theses environmental matrices have analytical problems, since a simple method doesn't exist for the purification, which is indispensable for its later measuring alpha spectrometry. The developed technique consist on taking an aliquot of the sample to analyze, to add tracer as americium 243 and curium 242, and to dissolve the matrix in a such way to have a clear solution. For the isolation of the americium and curium of the other actinides ar used as separation techniques: precipitation with Fe 3+ , anionic and cationic exchange, and extraction with a appropriate organic solvent. The purification of the americium and curium is followed by the electrodeposition habitually used. The measurement is carried out by alpha spectrometry with a detector of implanted ion. The detection limit for this techniques is of 0,002 Bq/l or 0,2 mBq in the case of filters. (author)

  18. Determination of the fraction of amorphous phases in superconducting samples

    International Nuclear Information System (INIS)

    Gomes Junior, G.G.; Ogasawara, T.; Amorim, H.S.

    2010-01-01

    The study phase formation of high critical temperature superconducting (Bi, Pb) - 2223 by partial melting and recrystallization aims to improve the microstructure of the material. Was used for X-ray diffraction characterization of the phases present. The DDM method (Derivative Difference Minimization) was used for the refinement of structures, quantification of the phases and determination the fraction of this amorphous. The advantage this method is not necessary to introduce an internal standard to determine the amorphous fraction. Were observed in the powder precursor phases (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O x (Bi, Pb) -2223, 93% of the sample, Bi 2 Sr 2 CaCu 2 O y (Bi-2212) and Bi 2 Sr 2 CuO z (Bi-2201). The powder precursor was heat treated at 820-870 deg C. To minimize volatilization of lead, the material was placed in silver crucibles closed. To get a high recovery of (Bi, Pb) - 2223, the material was cooled slowly, due to slow kinetic of formation of this phase. We observed a partial recovery phase (Bi, Pb) -2223. (author)

  19. Determination of Sr-90 in environmental samples using solid phase extraction disk

    International Nuclear Information System (INIS)

    Zal U'yun Wan Mahmood

    2002-01-01

    A method is described for determination of Sr-90 in environmental samples using solid phase extraction disk (Empore TM Strontium Rad Disk) and GM counter. To determine the optimum condition for capacity of Empore TM Strontium Rad Disk, its characterization studies such as the effects Sr content, acidity (molarity) of acids, presence of Ca 2+ and other major ions (Na + , Mg 2+ etc), influence of interference (Pb and Bi) and others were carried out. An optimized the using of Empore TM Strontium Rad Disk for determination of Sr-90 was validated by application to environmental samples. Quantitative recoveries above 95%for Sr (stable) were recorded in 6M HCl condition. Typical environmental samples may contain an assortment of anionic and cationic species, but in general, Empore TM Strontium Rad Disk has enough capacity to effectively separate Sr for wide variety of aqueous solutions. Sr recovery in a matrix-free or the content of matrix less than 300 mg/sample is typically greater than 99% is reported in this research work. In particular, sample, which may contain interference such as Pb and Bi would require an addition separation step before processing to ensure an accurate measurement of Sr. In this research work, radiotracer 85 Sr was used to monitor the behavior of Sr and calculation its recovery. For analytical methods that can count Y-90, the Sr-90 activity/concentration in environmental sample was calculated. The concentration of Sr-90 in ash sample (Quality Controled Sample) of 276 ± 18 Bq/kg ash was determined from Y-90 activity. The relative percent difference of 1.1% was achievable for Empore TM Sr-Rad Disk methods when compared to the conventional method (fumed-HNO 3 method) - 279 ± 11 Bq/kg ash. (Author)

  20. A Monte Carlo simulation technique to determine the optimal portfolio

    Directory of Open Access Journals (Sweden)

    Hassan Ghodrati

    2014-03-01

    Full Text Available During the past few years, there have been several studies for portfolio management. One of the primary concerns on any stock market is to detect the risk associated with various assets. One of the recognized methods in order to measure, to forecast, and to manage the existing risk is associated with Value at Risk (VaR, which draws much attention by financial institutions in recent years. VaR is a method for recognizing and evaluating of risk, which uses the standard statistical techniques and the method has been used in other fields, increasingly. The present study has measured the value at risk of 26 companies from chemical industry in Tehran Stock Exchange over the period 2009-2011 using the simulation technique of Monte Carlo with 95% confidence level. The used variability in the present study has been the daily return resulted from the stock daily price change. Moreover, the weight of optimal investment has been determined using a hybrid model called Markowitz and Winker model in each determined stocks. The results showed that the maximum loss would not exceed from 1259432 Rials at 95% confidence level in future day.

  1. Cloud point extraction, preconcentration and spectrophotometric determination of nickel in water samples using dimethylglyoxime

    Directory of Open Access Journals (Sweden)

    Morteza Bahram

    2013-01-01

    Full Text Available A new and simple method for the preconcentration and spectrophotometric determination of trace amounts of nickel was developed by cloud point extraction (CPE. In the proposed work, dimethylglyoxime (DMG was used as the chelating agent and Triton X-114 was selected as a non-ionic surfactant for CPE. The parameters affecting the cloud point extraction including the pH of sample solution, concentration of the chelating agent and surfactant, equilibration temperature and time were optimized. Under the optimum conditions, the calibration graph was linear in the range of 10-150 ng mL-1 with a detection limit of 4 ng mL-1. The relative standard deviation for 9 replicates of 100 ng mL-1 Ni(II was 1.04%. The interference effect of some anions and cations was studied. The method was applied to the determination of Ni(II in water samples with satisfactory results.

  2. Determination of proline in honey: comparison between official methods, optimization and validation of the analytical methodology.

    Science.gov (United States)

    Truzzi, Cristina; Annibaldi, Anna; Illuminati, Silvia; Finale, Carolina; Scarponi, Giuseppe

    2014-05-01

    The study compares official spectrophotometric methods for the determination of proline content in honey - those of the International Honey Commission (IHC) and the Association of Official Analytical Chemists (AOAC) - with the original Ough method. Results show that the extra time-consuming treatment stages added by the IHC method with respect to the Ough method are pointless. We demonstrate that the AOACs method proves to be the best in terms of accuracy and time saving. The optimized waiting time for the absorbance recording is set at 35min from the removal of reaction tubes from the boiling bath used in the sample treatment. The optimized method was validated in the matrix: linearity up to 1800mgL(-1), limit of detection 20mgL(-1), limit of quantification 61mgL(-1). The method was applied to 43 unifloral honey samples from the Marche region, Italy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Evaluation of metal ions in rice samples: extraction and direct determination by ICP OES

    International Nuclear Information System (INIS)

    Oliveira, Andrea; Cadore, Solange; Baccan, Nivaldo

    2012-01-01

    A method for extraction of metal ions present in rice samples using ammoniacal EDTA solution, pH = 10, as extractor agent is proposed under the following optimized conditions: 0.20 g of rice sample and 5.00 mL of ammoniacal EDTA (ethylenediaminetetraacetic acid) solution, with 5 min of ultrasound exposure time. Using robust ICP OES (inductively coupled plasma atomic emission spectrometry) conditions, direct analysis of the extraction solution was allowed, and the recovery values obtained were above 90% for most of the studied elements (P, K, Mg, Ca, Zn, Mn, Cu and Mo) with RSD -1 (Mn) - 48.68 mg kg -1 (K), showing adequate detectability for the determination of the analytes. The analysis of different samples indicated that Brazilian 'integral' rice contains higher contents of the constituents studied, followed by 'parboiled' rice, and the 'agulhinha' rice a long and thin grain type. (author)

  4. A projection method for under determined optimal experimental designs

    KAUST Repository

    Long, Quan; Scavino, Marco; Tempone, Raul; Wang, Suojin

    2014-01-01

    A new implementation, based on the Laplace approximation, was developed in (Long, Scavino, Tempone, & Wang 2013) to accelerate the estimation of the post–experimental expected information gains in the model parameters and predictive quantities of interest. A closed–form approximation of the inner integral and the order of the corresponding dominant error term were obtained in the cases where the parameters are determined by the experiment. In this work, we extend that method to the general cases where the model parameters could not be determined completely by the data from the proposed experiments. We carry out the Laplace approximations in the directions orthogonal to the null space of the corresponding Jacobian matrix, so that the information gain (Kullback–Leibler divergence) can be reduced to an integration against the marginal density of the transformed parameters which are not determined by the experiments. Furthermore, the expected information gain can be approximated by an integration over the prior, where the integrand is a function of the projected posterior covariance matrix. To deal with the issue of dimensionality in a complex problem, we use Monte Carlo sampling or sparse quadratures for the integration over the prior probability density function, depending on the regularity of the integrand function. We demonstrate the accuracy, efficiency and robustness of the proposed method via several nonlinear under determined numerical examples.

  5. A projection method for under determined optimal experimental designs

    KAUST Repository

    Long, Quan

    2014-01-09

    A new implementation, based on the Laplace approximation, was developed in (Long, Scavino, Tempone, & Wang 2013) to accelerate the estimation of the post–experimental expected information gains in the model parameters and predictive quantities of interest. A closed–form approximation of the inner integral and the order of the corresponding dominant error term were obtained in the cases where the parameters are determined by the experiment. In this work, we extend that method to the general cases where the model parameters could not be determined completely by the data from the proposed experiments. We carry out the Laplace approximations in the directions orthogonal to the null space of the corresponding Jacobian matrix, so that the information gain (Kullback–Leibler divergence) can be reduced to an integration against the marginal density of the transformed parameters which are not determined by the experiments. Furthermore, the expected information gain can be approximated by an integration over the prior, where the integrand is a function of the projected posterior covariance matrix. To deal with the issue of dimensionality in a complex problem, we use Monte Carlo sampling or sparse quadratures for the integration over the prior probability density function, depending on the regularity of the integrand function. We demonstrate the accuracy, efficiency and robustness of the proposed method via several nonlinear under determined numerical examples.

  6. Determination of total organic phosphorus in samples of mineral soils

    Directory of Open Access Journals (Sweden)

    Armi Kaila

    1962-01-01

    Full Text Available In this paper some observations on the estimation of organic phosphorus in mineral soils are reported. The fact is emphasized that the accuracy of all the methods available is relatively poor. Usually, there are no reasons to pay attention to differences less than about 20 ppm. of organic P. Analyses performed on 345 samples of Finnish mineral soils by the extraction method of MEHTA et. al. (10 and by a simple procedure adopted by the author (successive extractions with 4 N H2SO4 and 0.5 N NaOH at room temperature in the ratio of 1 to 100 gave, on the average, equal results. It seemed to be likely that the MEHTA method removed the organic phosphorus more completely than did the less vigorous method, but in the former the partial hydrolysis of organic phosphorus compounds tends to be higher than in the latter. An attempt was made to find out whether the differences between the respective values for organic phosphorus obtained by an ignition method and the simple extraction method could be connected with any characteristics of the soil. No correlation or only a low correlation coefficient could be calculated between the difference in the results of these two methods and e. g. the pH-value, the content of clay, organic carbon, aluminium and iron soluble in Tamm’s acid oxalate, the indicator of the phosphate sorption capacity, or the »Fe-bound» inorganic phosphorus, respectively. The absolute difference tended to increase with an increase in the content of organic phosphorus. For the 250 samples of surface soils analyzed, the ignition method gave values which were, on the average, about 50 ppm. higher than the results obtained by the extraction procedure. The corresponding difference for the 120 samples from deeper layers was about 20 ppm of organic P. The author recommends, for the present, the determination of the total soil organic phosphorus as an average of the results obtained by the ignition method and the extraction method.

  7. Determination of arsenic species in rice samples using CPE and ETAAS.

    Science.gov (United States)

    Costa, Bruno Elias Dos Santos; Coelho, Nívia Maria Melo; Coelho, Luciana Melo

    2015-07-01

    A highly sensitive and selective procedure for the determination of arsenate and total arsenic in food by electrothermal atomic absorption spectrometry after cloud point extraction (ETAAS/CPE) was developed. The procedure is based on the formation of a complex of As(V) ions with molybdate in the presence of 50.0 mmol L(-1) sulfuric acid. The complex was extracted into the surfactant-rich phase of 0.06% (w/v) Triton X-114. The variables affecting the complex formation, extraction and phase separation were optimized using factorial designs. Under the optimal conditions, the calibration graph was linear in the range of 0.05-10.0 μg L(-1). The detection and quantification limits were 10 and 33 ng L(-1), respectively and the corresponding value for the relative standard deviation for 10 replicates was below 5%. Recovery values of between 90.8% and 113.1% were obtained for spiked samples. The accuracy of the method was evaluated by comparison with the results obtained for the analysis of a rice flour sample (certified material IRMM-804) and no significant difference at the 95% confidence level was observed. The method was successfully applied to the determination of As(V) and total arsenic in rice samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Determination of phosphorus in small amounts of protein samples by ICP-MS.

    Science.gov (United States)

    Becker, J Sabine; Boulyga, Sergei F; Pickhardt, Carola; Becker, J; Buddrus, Stefan; Przybylski, Michael

    2003-02-01

    Inductively coupled plasma mass spectrometry (ICP-MS) is used for phosphorus determination in protein samples. A small amount of solid protein sample (down to 1 micro g) or digest (1-10 micro L) protein solution was denatured in nitric acid and hydrogen peroxide by closed-microvessel microwave digestion. Phosphorus determination was performed with an optimized analytical method using a double-focusing sector field inductively coupled plasma mass spectrometer (ICP-SFMS) and quadrupole-based ICP-MS (ICP-QMS). For quality control of phosphorus determination a certified reference material (CRM), single cell proteins (BCR 273) with a high phosphorus content of 26.8+/-0.4 mg g(-1), was analyzed. For studies on phosphorus determination in proteins while reducing the sample amount as low as possible the homogeneity of CRM BCR 273 was investigated. Relative standard deviation and measurement accuracy in ICP-QMS was within 2%, 3.5%, 11% and 12% when using CRM BCR 273 sample weights of 40 mg, 5 mg, 1 mg and 0.3 mg, respectively. The lowest possible sample weight for an accurate phosphorus analysis in protein samples by ICP-MS is discussed. The analytical method developed was applied for the analysis of homogeneous protein samples in very low amounts [1-100 micro g of solid protein sample, e.g. beta-casein or down to 1 micro L of protein or digest in solution (e.g., tau protein)]. A further reduction of the diluted protein solution volume was achieved by the application of flow injection in ICP-SFMS, which is discussed with reference to real protein digests after protein separation using 2D gel electrophoresis.The detection limits for phosphorus in biological samples were determined by ICP-SFMS down to the ng g(-1) level. The present work discusses the figure of merit for the determination of phosphorus in a small amount of protein sample with ICP-SFMS in comparison to ICP-QMS.

  9. Determination of gallic acid with rhodanine by reverse flow injection analysis using simplex optimization.

    Science.gov (United States)

    Phakthong, Wilaiwan; Liawruangrath, Boonsom; Liawruangrath, Saisunee

    2014-12-01

    A reversed flow injection (rFI) system was designed and constructed for gallic acid determination. Gallic acid was determined based on the formation of chromogen between gallic acid and rhodanine, resulting in a colored product with a λmax at 520 nm. The optimum conditions for determining gallic acid were also investigated. Optimizations of the experimental conditions were carried out based on the so-call univariate method. The conditions obtained were 0.6% (w/v) rhodanine, 70% (v/v) ethanol, 0.9 mol L(-1) NaOH, 2.0 mL min(-1) flow rate, 75 μL injection loop and 600 cm mixing tubing length, respectively. Comparative optimizations of the experimental conditions were also carried out by multivariate or simplex optimization method. The conditions obtained were 1.2% (w/v) rhodanine, 70% (v/v) ethanol, 1.2 mol L(-1) NaOH, flow rate 2.5 mL min(-1), 75 μL injection loop and 600 cm mixing tubing length, respectively. It was found that the optimum conditions obtained by the former optimization method were mostly similar to those obtained by the latter method. The linear relationship between peak height and the concentration of gallic acid was obtained over the range of 0.1-35.0 mg L(-1) with the detection limit 0.081 mg L(-1). The relative standard deviations were found to be in the ranges 0.46-1.96% for 1, 10, 30 mg L(-1) of gallic acid (n=11). The method has the advantages of simplicity extremely high selectivity and high precision. The proposed method was successfully applied to the determination of gallic acid in longan samples without interferent effects from other common phenolic compounds that might be present in the longan samples collected in northern Thailand. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2014-05-01

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

  11. Automatic Motion Generation for Robotic Milling Optimizing Stiffness with Sample-Based Planning

    Directory of Open Access Journals (Sweden)

    Julian Ricardo Diaz Posada

    2017-01-01

    Full Text Available Optimal and intuitive robotic machining is still a challenge. One of the main reasons for this is the lack of robot stiffness, which is also dependent on the robot positioning in the Cartesian space. To make up for this deficiency and with the aim of increasing robot machining accuracy, this contribution describes a solution approach for optimizing the stiffness over a desired milling path using the free degree of freedom of the machining process. The optimal motion is computed based on the semantic and mathematical interpretation of the manufacturing process modeled on its components: product, process and resource; and by configuring automatically a sample-based motion problem and the transition-based rapid-random tree algorithm for computing an optimal motion. The approach is simulated on a CAM software for a machining path revealing its functionality and outlining future potentials for the optimal motion generation for robotic machining processes.

  12. Determination of lead in rice grains by solid sampling HR-CS GFAAS.

    Science.gov (United States)

    Gunduz, Sema; Akman, Suleyman

    2013-12-01

    A study was performed for the determination of lead in rice grains directly by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) without digesting sample. The effects of sample amount, pyrolysis/atomization temperatures on the determination of lead in rice were investigated and optimized using a certificated rice flour. The lead concentrations were determined applying 800 °C of pyrolysis and 1800 °C of atomization temperatures without modifier. LOD (N=10, 3σ) and characteristic mass were 2.3 μg kg(-1) and 8.1 pg, respectively. The certified lead value of a rice flour CRM was found in its uncertainity limits. The lead contents of various rice samples obtained from markets in Turkey were between 0.009 and 0.162 mg kg(-1) which are in acceptable range. The average lead concentrations in various rice grains taken from the same package were significantly different from each other. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Gamut Volume Index: a color preference metric based on meta-analysis and optimized colour samples.

    Science.gov (United States)

    Liu, Qiang; Huang, Zheng; Xiao, Kaida; Pointer, Michael R; Westland, Stephen; Luo, M Ronnier

    2017-07-10

    A novel metric named Gamut Volume Index (GVI) is proposed for evaluating the colour preference of lighting. This metric is based on the absolute gamut volume of optimized colour samples. The optimal colour set of the proposed metric was obtained by optimizing the weighted average correlation between the metric predictions and the subjective ratings for 8 psychophysical studies. The performance of 20 typical colour metrics was also investigated, which included colour difference based metrics, gamut based metrics, memory based metrics as well as combined metrics. It was found that the proposed GVI outperformed the existing counterparts, especially for the conditions where correlated colour temperatures differed.

  14. Sampling procedure, receipt and conservation of water samples to determine environmental radioactivity

    International Nuclear Information System (INIS)

    Herranz, M.; Navarro, E.; Payeras, J.

    2009-01-01

    The present document informs about essential goals, processes and contents that the subgroups Sampling and Samples Preparation and Conservation believe they should be part of the procedure to obtain a correct sampling, receipt, conservation and preparation of samples of continental, marine and waste water before qualifying its radioactive content.

  15. A Simple Analytical Method Using HPLC with Fluorescence Detection to Determine Selected Polycyclic Aromatic Compounds in Filter Samples

    International Nuclear Information System (INIS)

    Garcia, S.; Perez, R. M.

    2014-01-01

    A study on the comparison and evaluation of a miniaturized extraction method for the determination of selected PACs in sample filters is presented. The main objective was the optimization and development of simple, rapid and low cost methods, minimizing the use of extracting solvent volume. The work also includes a study on the intermediate precision. (Author)

  16. Approximate determination of efficiency for activity measurements of cylindrical samples

    Energy Technology Data Exchange (ETDEWEB)

    Helbig, W [Nuclear Engineering and Analytics Rossendorf, Inc. (VKTA), Dresden (Germany); Bothe, M [Nuclear Engineering and Analytics Rossendorf, Inc. (VKTA), Dresden (Germany)

    1997-03-01

    Some calibration samples are necessary with the same geometrical parameters but of different materials, containing known activities A homogeniously distributed. Their densities are measured, their mass absorption coefficients may be unknown. These calibration samples are positioned in the counting geometry, for instance directly on the detector. The efficiency function {epsilon}(E) for each sample is gained by measuring the gamma spectra and evaluating all usable gamma energy peaks. From these {epsilon}(E) the common valid {epsilon}{sub geom}(E) will be deduced. For this purpose the functions {epsilon}{sub mu}(E) for these samples have to be established. (orig.)

  17. A normative inference approach for optimal sample sizes in decisions from experience

    Science.gov (United States)

    Ostwald, Dirk; Starke, Ludger; Hertwig, Ralph

    2015-01-01

    “Decisions from experience” (DFE) refers to a body of work that emerged in research on behavioral decision making over the last decade. One of the major experimental paradigms employed to study experience-based choice is the “sampling paradigm,” which serves as a model of decision making under limited knowledge about the statistical structure of the world. In this paradigm respondents are presented with two payoff distributions, which, in contrast to standard approaches in behavioral economics, are specified not in terms of explicit outcome-probability information, but by the opportunity to sample outcomes from each distribution without economic consequences. Participants are encouraged to explore the distributions until they feel confident enough to decide from which they would prefer to draw from in a final trial involving real monetary payoffs. One commonly employed measure to characterize the behavior of participants in the sampling paradigm is the sample size, that is, the number of outcome draws which participants choose to obtain from each distribution prior to terminating sampling. A natural question that arises in this context concerns the “optimal” sample size, which could be used as a normative benchmark to evaluate human sampling behavior in DFE. In this theoretical study, we relate the DFE sampling paradigm to the classical statistical decision theoretic literature and, under a probabilistic inference assumption, evaluate optimal sample sizes for DFE. In our treatment we go beyond analytically established results by showing how the classical statistical decision theoretic framework can be used to derive optimal sample sizes under arbitrary, but numerically evaluable, constraints. Finally, we critically evaluate the value of deriving optimal sample sizes under this framework as testable predictions for the experimental study of sampling behavior in DFE. PMID:26441720

  18. Optimal sampling period of the digital control system for the nuclear power plant steam generator water level control

    International Nuclear Information System (INIS)

    Hur, Woo Sung; Seong, Poong Hyun

    1995-01-01

    A great effort has been made to improve the nuclear plant control system by use of digital technologies and a long term schedule for the control system upgrade has been prepared with an aim to implementation in the next generation nuclear plants. In case of digital control system, it is important to decide the sampling period for analysis and design of the system, because the performance and the stability of a digital control system depend on the value of the sampling period of the digital control system. There is, however, currently no systematic method used universally for determining the sampling period of the digital control system. Generally, a traditional way to select the sampling frequency is to use 20 to 30 times the bandwidth of the analog control system which has the same system configuration and parameters as the digital one. In this paper, a new method to select the sampling period is suggested which takes into account of the performance as well as the stability of the digital control system. By use of the Irving's model steam generator, the optimal sampling period of an assumptive digital control system for steam generator level control is estimated and is actually verified in the digital control simulation system for Kori-2 nuclear power plant steam generator level control. Consequently, we conclude the optimal sampling period of the digital control system for Kori-2 nuclear power plant steam generator level control is 1 second for all power ranges. 7 figs., 3 tabs., 8 refs. (Author)

  19. Field-amplified sample stacking-sweeping of vitamins B determination in capillary electrophoresis.

    Science.gov (United States)

    Dziomba, Szymon; Kowalski, Piotr; Bączek, Tomasz

    2012-12-07

    A capillary electrophoretic method for determination of five water soluble vitamins B along with baclofen as an internal standard has been developed and assessed in context of precision, accuracy, sensitivity, freedom from interference, linearity, detection and quantification limits. On-line preconcentration technique, namely field-amplified sample stacking (FASS)-sweeping, has been employed in respect to obtain more sensitive analysis. Separation conditions received after optimization procedure were as following background electrolyte (BGE), 10 mM NaH(2)PO(4), 80 mM SDS, (pH 7.25); sample matrix (SM), 10 mM NaH(2)PO(4) (pH 4.60); uncoated fused silica capillary (50 μm i.d. × 67 cm length); UV spectrophotometric detection at 200 nm; injection times: 10s and 30s at 3.45 kPa; applied voltage 22 kV; temperature 22°C. Validation parameters, namely precision, accuracy and linearity, were considered as satisfactory. Under the optimized conditions, it has been also successfully applied for vitamins B determination in bacterial growth medium and commercially available Ilex paraguariensis leaves. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Slurry sampling in serum blood for mercury determination by CV-AFS

    International Nuclear Information System (INIS)

    Aranda, Pedro R.; Gil, Raul A.; Moyano, Susana; De Vito, Irma; Martinez, Luis D.

    2009-01-01

    The heavy metal mercury (Hg) is a neurotoxin known to have a serious health impact even at relatively low concentrations. A slurry method was developed for the sensitive and precise determination of mercury in human serum blood samples by cold vapor generation coupled to atomic fluorescence spectrometry (CV-AFS). All variables related to the slurry formation were studied. The optimal hydrochloric concentration and tin(II) chloride concentration for CV generation were evaluated. Calibration within the range 0.1-10 μg L -1 Hg was performed with the standard addition method, and compared with an external calibration. Additionally, the reliability of the results obtained was evaluated by analyzing mercury in the same samples, but submitted to microwave-assisted digestion method. The limit of detection was calculated as 25 ng L -1 and the relative standard deviation was 3.9% at levels around of 0.4 μg L -1 Hg

  1. Integration of electromagnetic induction sensor data in soil sampling scheme optimization using simulated annealing.

    Science.gov (United States)

    Barca, E; Castrignanò, A; Buttafuoco, G; De Benedetto, D; Passarella, G

    2015-07-01

    Soil survey is generally time-consuming, labor-intensive, and costly. Optimization of sampling scheme allows one to reduce the number of sampling points without decreasing or even increasing the accuracy of investigated attribute. Maps of bulk soil electrical conductivity (EC a ) recorded with electromagnetic induction (EMI) sensors could be effectively used to direct soil sampling design for assessing spatial variability of soil moisture. A protocol, using a field-scale bulk EC a survey, has been applied in an agricultural field in Apulia region (southeastern Italy). Spatial simulated annealing was used as a method to optimize spatial soil sampling scheme taking into account sampling constraints, field boundaries, and preliminary observations. Three optimization criteria were used. the first criterion (minimization of mean of the shortest distances, MMSD) optimizes the spreading of the point observations over the entire field by minimizing the expectation of the distance between an arbitrarily chosen point and its nearest observation; the second criterion (minimization of weighted mean of the shortest distances, MWMSD) is a weighted version of the MMSD, which uses the digital gradient of the grid EC a data as weighting function; and the third criterion (mean of average ordinary kriging variance, MAOKV) minimizes mean kriging estimation variance of the target variable. The last criterion utilizes the variogram model of soil water content estimated in a previous trial. The procedures, or a combination of them, were tested and compared in a real case. Simulated annealing was implemented by the software MSANOS able to define or redesign any sampling scheme by increasing or decreasing the original sampling locations. The output consists of the computed sampling scheme, the convergence time, and the cooling law, which can be an invaluable support to the process of sampling design. The proposed approach has found the optimal solution in a reasonable computation time. The

  2. Determination of Pu in soil samples; Determinacion de Pu en muestras de suelo

    Energy Technology Data Exchange (ETDEWEB)

    Torres C, C. O.; Hernandez M, H.; Romero G, E. T. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Vega C, H. R., E-mail: carioli_32907@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

    2016-10-15

    The irreversible consequences of accidents occurring in nuclear plants and in nuclear fuel reprocessing sites are mainly the distribution of different radionuclides in different matrices such as the soil. The distribution in the superficial soil is related to the internal and external exposure to the radiation of the affected population. The internal contamination with radionuclides such as Pu is of great relevance to the nuclear forensic science, where is important to know the chemical and isotopic compositions of nuclear materials. The objective of this work is to optimize the radiochemical separation of plutonium (Pu) from soil samples and to determine their concentration. The soil samples were prepared using acid digestion assisted by microwave; purification of Pu was carried out with AG1X8 resin using ion exchange chromatography. Pu isotopes were measured using ICP-SFMS. In order to reduce the interference due to the presence of {sup 238}UH {sup +} in the samples, a solvent removal system (Apex) was used. In addition, the limit of detection and quantification of Pu was determined. It was found that the recovery efficiency of Pu in soil samples ranges from 70 to 93%. (Author)

  3. Optimization of sample preparation variables for wedelolactone from Eclipta alba using Box-Behnken experimental design followed by HPLC identification.

    Science.gov (United States)

    Patil, A A; Sachin, B S; Shinde, D B; Wakte, P S

    2013-07-01

    Coumestan wedelolactone is an important phytocomponent from Eclipta alba (L.) Hassk. It possesses diverse pharmacological activities, which have prompted the development of various extraction techniques and strategies for its better utilization. The aim of the present study is to develop and optimize supercritical carbon dioxide assisted sample preparation and HPLC identification of wedelolactone from E. alba (L.) Hassk. The response surface methodology was employed to study the optimization of sample preparation using supercritical carbon dioxide for wedelolactone from E. alba (L.) Hassk. The optimized sample preparation involves the investigation of quantitative effects of sample preparation parameters viz. operating pressure, temperature, modifier concentration and time on yield of wedelolactone using Box-Behnken design. The wedelolactone content was determined using validated HPLC methodology. The experimental data were fitted to second-order polynomial equation using multiple regression analysis and analyzed using the appropriate statistical method. By solving the regression equation and analyzing 3D plots, the optimum extraction conditions were found to be: extraction pressure, 25 MPa; temperature, 56 °C; modifier concentration, 9.44% and extraction time, 60 min. Optimum extraction conditions demonstrated wedelolactone yield of 15.37 ± 0.63 mg/100 g E. alba (L.) Hassk, which was in good agreement with the predicted values. Temperature and modifier concentration showed significant effect on the wedelolactone yield. The supercritical carbon dioxide extraction showed higher selectivity than the conventional Soxhlet assisted extraction method. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  4. The determination of radionuclides in grass ecosystem samples

    International Nuclear Information System (INIS)

    LaBrecque, J.J.; Schelenz, R.; Perkins, R.W.

    1987-07-01

    The radioactive debris cloud from the Chernobyl reactor accident resulted in some deposition over essentially all of the Northern Hemisphere. Shortly after the accident invitations were sent out by the IAEA to Member States to collect grass samples according to specific instructions so that the ratio of the various radionuclides in the fallout debris could be established over a wide area of Europe. In response to this request, 20 grass samples were provided by Member States. To establish a protocol for analysis of these valuable samples and to recommend a protocol for future sample collection, a Consultants Meeting was called by the IAEA for 23-25 September 1986. This document contains the considerations and recommendations of the consultants

  5. Hydrazine Determination in Sludge Samples by High Performance Liquid Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    G. Elias; G. A. Park

    2006-02-01

    A high-performance liquid chromatographic method using ultraviolet (UV) detection was developed to detect and quantify hydrazine in a variety of environmental matrices. The method was developed primarily for sludge samples, but it is also applicable to soil and water samples. The hydrazine in the matrices was derivatized to their hydrazones with benzaldehyde. The derivatized hydrazones were separated using high performance liquid chromatography (HPLC) with a reversed-phase C-18 column in an isocratic mode with methanol-water (95:5, v/v), and detected with UV detection at 313 nm. The detection limit (25 ml) for the new analytical method is 0.0067 mg ml-1of hydrazine. Hydrazine showed low recovery in soil samples because components in soil oxidized hydrazine. Sludge samples that contained relatively high soil content also showed lower recovery. The technique is relatively simple and cost-effective, and is applicable for hydrazine analysis in different environmental matrices.

  6. 7 CFR 28.25 - Samples for Form A determination.

    Science.gov (United States)

    2010-01-01

    ... shall be at least six (6) inches wide and approximately twelve (12) inches long and shall weigh at least..., trimming, or discarding part of the sample is prohibited. No part of the cotton or pieces of bagging, leaf...

  7. An integrated approach for multi-level sample size determination

    International Nuclear Information System (INIS)

    Lu, M.S.; Teichmann, T.; Sanborn, J.B.

    1997-01-01

    Inspection procedures involving the sampling of items in a population often require steps of increasingly sensitive measurements, with correspondingly smaller sample sizes; these are referred to as multilevel sampling schemes. In the case of nuclear safeguards inspections verifying that there has been no diversion of Special Nuclear Material (SNM), these procedures have been examined often and increasingly complex algorithms have been developed to implement them. The aim in this paper is to provide an integrated approach, and, in so doing, to describe a systematic, consistent method that proceeds logically from level to level with increasing accuracy. The authors emphasize that the methods discussed are generally consistent with those presented in the references mentioned, and yield comparable results when the error models are the same. However, because of its systematic, integrated approach the proposed method elucidates the conceptual understanding of what goes on, and, in many cases, simplifies the calculations. In nuclear safeguards inspections, an important aspect of verifying nuclear items to detect any possible diversion of nuclear fissile materials is the sampling of such items at various levels of sensitivity. The first step usually is sampling by ''attributes'' involving measurements of relatively low accuracy, followed by further levels of sampling involving greater accuracy. This process is discussed in some detail in the references given; also, the nomenclature is described. Here, the authors outline a coordinated step-by-step procedure for achieving such multilevel sampling, and they develop the relationships between the accuracy of measurement and the sample size required at each stage, i.e., at the various levels. The logic of the underlying procedures is carefully elucidated; the calculations involved and their implications, are clearly described, and the process is put in a form that allows systematic generalization

  8. Simplex optimization of the variables influencing the determination of pefloxacin by time-resolved chemiluminescence

    Science.gov (United States)

    Murillo Pulgarín, José A.; Alañón Molina, Aurelia; Jiménez García, Elisa

    2018-03-01

    A new chemiluminescence (CL) detection system combined with flow injection analysis (FIA) for the determination of Pefloxacin is proposed. The determination is based on an energy transfer from Pefloxacin to terbium (III). The metal ion enhances the weak CL signal produced by the KMnO4/H2SO3/Pefloxacin system. A modified simplex method was used to optimize chemical and instrumental variables. The influence of the interaction of the permanganate, Tb (III), sodium sulphite and sulphuric acid concentrations, flow rate and injected sample volume was thoroughly investigated by using a modified simplex optimization procedure. The results revealed a strong direct relationship between flow rate and CL intensity throughout the studied range that was confirmed by a gamma test. The response factor for the CL emission intensity was used to assess performance in order to identify the optimum conditions for maximization of the response. Under such conditions, the CL response was proportional to the Pefloxacin concentration over a wide range. The detection limit as calculated according to Clayton's criterion 13.7 μg L- 1. The analyte was successfully determined in milk samples with an average recovery of 100.6 ± 9.8%.

  9. Optimizing headspace sampling temperature and time for analysis of volatile oxidation products in fish oil

    DEFF Research Database (Denmark)

    Rørbæk, Karen; Jensen, Benny

    1997-01-01

    Headspace-gas chromatography (HS-GC), based on adsorption to Tenax GR(R), thermal desorption and GC, has been used for analysis of volatiles in fish oil. To optimize sam sampling conditions, the effect of heating the fish oil at various temperatures and times was evaluated from anisidine values (AV...

  10. Isolation and identification of phytase-producing strains from soil samples and optimization of production parameters

    Directory of Open Access Journals (Sweden)

    Masoud Mohammadi

    2017-09-01

    Discussion and conclusion: Penicillium sp. isolated from a soil sample near Qazvin, was able to produce highly active phytase in optimized environmental conditions, which could be a suitable candidate for commercial production of phytase to be used as complement in poultry feeding industries.

  11. Optimization of the Analytical Method Using HPLC with Fluorescence Detection to Determine Selected Polycyclic Aromatic Compounds in Clean Water Samples; Optimizacion del Metodo Analitico mediante HPLC con Detector de Fluorescencia para la Determinacion de Ciertos Compuestos Aromaticos Policiclicos en Muestras de Aguas Limpias

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Alonso, S.; Perez Pastor, R. M.

    2013-10-01

    A study on the comparison and evaluation of 3 miniaturized extraction methods for the determination of selected PACs in clear waters is presented. Three types of liquid-liquid extraction were used for chromatographic analysis by HPLC with fluorescence detection. The main objective was the optimization and development of simple, rapid and low cost methods, minimizing the use of extracting solvent volume. The work also includes a study on the scope of the methods developed at low and high levels of concentration and intermediate precision. (Author)

  12. Evaluation of Gravimetric Tar Determination in Particle Samples

    DEFF Research Database (Denmark)

    Hindsgaul, Claus; Henriksen, Ulrik B.; Bentzen, Jens Dall

    2000-01-01

    A comparison of tar determination of particles from a down-draft gasifier using soxhlet extractions (with anisole, dichloromethane and acetone) and pyrolysis of the particles.......A comparison of tar determination of particles from a down-draft gasifier using soxhlet extractions (with anisole, dichloromethane and acetone) and pyrolysis of the particles....

  13. Analysis of volatile organic compounds in compost samples: A potential tool to determine appropriate composting time.

    Science.gov (United States)

    Zhu, Fengxiang; Pan, Zaifa; Hong, Chunlai; Wang, Weiping; Chen, Xiaoyang; Xue, Zhiyong; Yao, Yanlai

    2016-12-01

    Changes in volatile organic compound contents in compost samples during pig manure composting were studied using a headspace, solid-phase micro-extraction method (HS-SPME) followed by gas chromatography with mass spectrometric detection (GC/MS). Parameters affecting the SPME procedure were optimized as follows: the coating was carbon molecular sieve/polydimethylsiloxane (CAR/PDMS) fiber, the temperature was 60°C and the time was 30min. Under these conditions, 87 compounds were identified from 17 composting samples. Most of the volatile components could only be detected before day 22. However, benzenes, alkanes and alkenes increased and eventually stabilized after day 22. Phenol and acid substances, which are important factors for compost quality, were almost undetectable on day 39 in natural compost (NC) samples and on day 13 in maggot-treated compost (MC) samples. Our results indicate that the approach can be effectively used to determine the composting times by analysis of volatile substances in compost samples. An appropriate composting time not only ensures the quality of compost and reduces the loss of composting material but also reduces the generation of hazardous substances. The appropriate composting times for MC and NC were approximately 22days and 40days, respectively, during the summer in Zhejiang. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Comparison of supercritical fluid extraction and Soxhlet extraction for the determination of PCBs in seaweed samples.

    Science.gov (United States)

    Punín Crespo, M O; Lage Yusty, M A

    2005-06-01

    The efficiency of supercritical fluid extraction for the determination of 12 polychlorinated biphenyls from algae samples is compared to Soxhlet extraction. Analytical detection limits for the individual congeners ranged from 0.62 microgl(-1) to 19 microgl(-1). Recovery was tested for both methods using standard addition procedure. At maximum spike level of concentration, the mean recoveries were not significantly different (P>0.05) of all PCBs studied, with the exception of PCBs 28, 52, 77 and 169. Method precision for Soxhlet extraction (yield comparable results, SFE offers the advantage of detecting all PCBs studied at lower concentrations, reducing extraction time, and reducing the amount of solvents needed. The optimized methods were applied to the analysis of three real seaweed samples, except for PCB101 the concentrations of all PCBs were low or below the detection limits. The levels of PCB101 found in sample 1 were 6.6+/-0.54 ng g(-1) d.w., in sample 2 the levels were 8.2+/-0.86 ng g(-1) d.w. and in sample 3 they were 7.7+/-0.08 ng g(-1) d.w.

  15. Use of passive sampling devices to determine soil contaminant concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, K.A. [Clemson Univ., Pendleton, SC (United States)]|[Washington State Univ., Richland, WA (United States); Hooper, M.J. [Clemson Univ., Pendleton, SC (United States); Weisskopf, C.P. [Washington State Univ., Richland, WA (United States)

    1996-12-31

    The effective remediation of contaminated sites requires accurate identification of chemical distributions. A rapid sampling method using passive sampling devices (PSDs) can provide a thorough site assessment. We have been pursuing their application in terrestrial systems and have found that they increase the ease and speed of analysis, decrease solvent usage and overall cost, and minimize the transport of contaminated soils. Time and cost savings allow a higher sampling frequency than is generally the case using traditional methods. PSDs have been used in the field in soils of varying physical properties and have been successful in estimating soil concentrations ranging from 1 {mu}g/kg (parts per billion) to greater than 200 mg/kg (parts per million). They were also helpful in identifying hot spots within the sites. Passive sampling devices show extreme promise as an analytical tool to rapidly characterize contaminant distributions in soil. There are substantial time and cost savings in laboratory personnel and supplies. By selectively excluding common interferences that require sample cleanup, PSDs can be retrieved from the field and processed rapidly (one technician can process approximately 90 PSDs in an 8-h work day). The results of our studies indicate that PSDs can be used to accurately estimate soil contaminant concentrations and provide lower detection limits. Further, time and cost savings will allow a more thorough and detailed characterization of contaminant distributions. 13 refs., 4 figs., 2 tabs.

  16. Neutron cross-section determination in geological samples (U)

    International Nuclear Information System (INIS)

    Harris, J.M.; McDaniel, P.J.

    1982-01-01

    The Prompt Gamma Neutron Activation Analysis (PGAA) technique yields elemental composition data which can be used to calculate the macroscopic cross section for any sample. The Small Sample Reactivity Measurements (SSRM) technique yields the macroscopic thermal absorption directly. Experimentally, PGAA is somewhat more difficult because of the calibration and data handling than is SSRM. However, SSRM requires a mathematical model of the reactor which means a rather complicated analysis. Once the model and calibration are completed, data analysis is routine. The SSRM technique is production oriented. 9 figures

  17. On Using a Pilot Sample Variance for Sample Size Determination in the Detection of Differences between Two Means: Power Consideration

    Science.gov (United States)

    Shieh, Gwowen

    2013-01-01

    The a priori determination of a proper sample size necessary to achieve some specified power is an important problem encountered frequently in practical studies. To establish the needed sample size for a two-sample "t" test, researchers may conduct the power analysis by specifying scientifically important values as the underlying population means…

  18. Optimized IMAC-IMAC protocol for phosphopeptide recovery from complex biological samples

    DEFF Research Database (Denmark)

    Ye, Juanying; Zhang, Xumin; Young, Clifford

    2010-01-01

    using Fe(III)-NTA IMAC resin and it proved to be highly selective in the phosphopeptide enrichment of a highly diluted standard sample (1:1000) prior to MALDI MS analysis. We also observed that a higher iron purity led to an increased IMAC enrichment efficiency. The optimized method was then adapted...... to phosphoproteome analyses of cell lysates of high protein complexity. From either 20 microg of mouse sample or 50 microg of Drosophila melanogaster sample, more than 1000 phosphorylation sites were identified in each study using IMAC-IMAC and LC-MS/MS. We demonstrate efficient separation of multiply phosphorylated...... characterization of phosphoproteins in functional phosphoproteomics research projects....

  19. An overview of the main foodstuff sample preparation technologies for tetracycline residue determination.

    Science.gov (United States)

    Pérez-Rodríguez, Michael; Pellerano, Roberto Gerardo; Pezza, Leonardo; Pezza, Helena Redigolo

    2018-05-15

    Tetracyclines are widely used for both the treatment and prevention of diseases in animals as well as for the promotion of rapid animal growth and weight gain. This practice may result in trace amounts of these drugs in products of animal origin, such as milk and eggs, posing serious risks to human health. The presence of tetracycline residues in foods can lead to the transmission of antibiotic-resistant pathogenic bacteria through the food chain. In order to ensure food safety and avoid exposure to these substances, national and international regulatory agencies have established tolerance levels for authorized veterinary drugs, including tetracycline antimicrobials. In view of that, numerous sensitive and specific methods have been developed for the quantification of these compounds in different food matrices. One will note, however, that the determination of trace residues in foods such as milk and eggs often requires extensive sample extraction and preparation prior to conducting instrumental analysis. Sample pretreatment is usually the most complicated step in the analytical process and covers both cleaning and pre-concentration. Optimal sample preparation can reduce analysis time and sources of error, enhance sensitivity, apart from enabling unequivocal identification, confirmation and quantification of target analytes. The development and implementation of more environmentally friendly analytical procedures, which involve the use of less hazardous solvents and smaller sample sizes compared to traditional methods, is a rapidly increasing trend in analytical chemistry. This review seeks to provide an updated overview of the main trends in sample preparation for the determination of tetracycline residues in foodstuffs. The applicability of several extraction and clean-up techniques employed in the analysis of foodstuffs, especially milk and egg samples, is also thoroughly discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Sample preparation of waste water to determine metallic contaminants by X-ray fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Gonzalez Olivos, Javier.

    1987-01-01

    Trace X-ray fluorescence spectroscopy analysis in liquid samples is preceded by sample preparation, which usually consists in the precipitation of the metallic ions and concentration over a thin cellulose filter. The samples preparation of waste water by this method is not efficient, due to the great amount of organic and insoluble matter that they contain. The purpose of this work was to determine the optimal value of pH in order to adsorbe all the insoluble matter contained in a waste water sample in the activated charcoal, so that the metallic ions could be precipitated and concentrated on a thin filter and determinated by X-ray fluorescence spectroscopy. A survey about the adsorption of some ions in activated charcoal in function of the pH was made for the following: Cr 3+ , Fe 3+ , Ni 2+ , Cu 2+ , Zn 2+ , Se 2+ , Hg 2+ , and Pb 2+ . It was observed that at pH 0, the ions are not adsorbed, but Cu 2+ and Zn 2+ are adsorbed in small amount; at pH 14, the ions are adsorbed, excluding Se, which is not adsorbed at any value of pH. If a waste water sample is treated at pH 0 with activated charcoal to adsorbe the organic and insoluble matter, most of the metallic ions are not adsorbed by the activated charcoal and could be precipitated with APDC (ammonium 1-pirrolidine dithio carbamate salt) and concentrated on a thin filter. The analysis of the metallic ions contained on the filter and those adsorbed in the activated charcoal by X-ray fluorescence spectroscopy, gave the total amount of the ions in the sample. (author)

  1. Determination of toxic trace elements in body fluid reference samples

    International Nuclear Information System (INIS)

    Gills, T.E.; McClendon, L.T.; Maienthal, E.J.; Becker, D.A.; Durst, R.A.; LaFleur, P.D.

    1974-01-01

    The measurement of elemental concentration in body fluids has been widely used to give indication of exposures to certain toxic materials and/or a measure of body burden. To understand fully the toxicological effect of these trace elements on our physiological system, meaningful analytical data are required along with accurate standards or reference samples. The National Bureau of Standards has prepared for the National Institute for Occupational Safety and Health (NIOSH) a number of reference samples containing selected toxic trace elements in body fluids. The reference samples produced include mercury in urine at three concentration levels, five elements (Se, Cu, As, Ni and Cr) in freeze-dried urine at two levels, fluorine in freeze-dried urine at two levels and lead in blood at two concentration levels. These reference samples have been found to be extremely useful for the evaluation of field and laboratory analytical methods for the analysis of toxic trace elements. In particular the use of at least two calibration points (i.e., ''normal'' and ''elevated'' levels) for a given matrix provides a more positive calibration for most analytical techniques over the range of interest for occupational toxicological levels of exposure. (U.S.)

  2. Determination of Phenols in Water Samples using a Supported ...

    African Journals Online (AJOL)

    NJD

    This was achieved by pH adjustments in the sample and acceptor phases. The method was ... during wastewater treatment, since chlorine is added as a disinfectant. ... they give a high degree of selectivity and clean-up, use little or no organic ...

  3. Optimism and self-esteem are related to sleep. Results from a large community-based sample.

    Science.gov (United States)

    Lemola, Sakari; Räikkönen, Katri; Gomez, Veronica; Allemand, Mathias

    2013-12-01

    There is evidence that positive personality characteristics, such as optimism and self-esteem, are important for health. Less is known about possible determinants of positive personality characteristics. To test the relationship of optimism and self-esteem with insomnia symptoms and sleep duration. Sleep parameters, optimism, and self-esteem were assessed by self-report in a community-based sample of 1,805 adults aged between 30 and 84 years in the USA. Moderation of the relation between sleep and positive characteristics by gender and age as well as potential confounding of the association by depressive disorder was tested. Individuals with insomnia symptoms scored lower on optimism and self-esteem largely independent of age and sex, controlling for symptoms of depression and sleep duration. Short sleep duration (self-esteem when compared to individuals sleeping 7-8 h, controlling depressive symptoms. Long sleep duration (>9 h) was also related to low optimism and self-esteem independent of age and sex. Good and sufficient sleep is associated with positive personality characteristics. This relationship is independent of the association between poor sleep and depression.

  4. Column preconcentration and electrothermal atomic absorption spectrometric determination of rhodium in some food and standard samples.

    Science.gov (United States)

    Taher, Mohammad Ali; Pourmohammad, Fatemeh; Fazelirad, Hamid

    2015-12-01

    In the present work, an electrothermal atomic absorption spectrometric method has been developed for the determination of ultra-trace amounts of rhodium after adsorption of its 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol/tetraphenylborate ion associated complex at the surface of alumina. Several factors affecting the extraction efficiency such as the pH, type of eluent, sample and eluent flow rates, sorption capacity of alumina and sample volume were investigated and optimized. The relative standard deviation for eight measurements of 0.1 ng/mL of rhodium was ±6.3%. In this method, the detection limit was 0.003 ng/mL in the original solution. The sorption capacity of alumina and the linear range for Rh(III) were evaluated as 0.8 mg/g and 0.015-0.45 ng/mL in the original solution, respectively. The proposed method was successfully applied for the extraction and determination of rhodium content in some food and standard samples with high recovery values. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Topologically determined optimal stochastic resonance responses of spatially embedded networks

    International Nuclear Information System (INIS)

    Gosak, Marko; Marhl, Marko; Korosak, Dean

    2011-01-01

    We have analyzed the stochastic resonance phenomenon on spatial networks of bistable and excitable oscillators, which are connected according to their location and the amplitude of external forcing. By smoothly altering the network topology from a scale-free (SF) network with dominating long-range connections to a network where principally only adjacent oscillators are connected, we reveal that besides an optimal noise intensity, there is also a most favorable interaction topology at which the best correlation between the response of the network and the imposed weak external forcing is achieved. For various distributions of the amplitudes of external forcing, the optimal topology is always found in the intermediate regime between the highly heterogeneous SF network and the strong geometric regime. Our findings thus indicate that a suitable number of hubs and with that an optimal ratio between short- and long-range connections is necessary in order to obtain the best global response of a spatial network. Furthermore, we link the existence of the optimal interaction topology to a critical point indicating the transition from a long-range interactions-dominated network to a more lattice-like network structure.

  6. Use of Simplex Method in Determination of Optimal Rational ...

    African Journals Online (AJOL)

    The optimal rational composition was found to be: Nsu Clay = 47.8%, quartz = 33.7% and CaCO3 = 18.5%. The other clay from Ukpor was found unsuitable at the firing temperature (l000°C) used. It showed bending strength lower than the standard requirement for all compositions studied. To improve the strength an ...

  7. Trace determination of uranium in fertilizer samples by total ...

    Indian Academy of Sciences (India)

    Uranium is reported to be present in phosphate fertilizers. The recovery of uranium from the fertilizers is important because it can be used as fuel in nuclear reactors and also because of environmental concerns. For both these activities suitable method of uranium determinations at trace levels in these fertilizers are required.

  8. Application of response surface methodology for determination of methyl red in water samples by spectrophotometry method.

    Science.gov (United States)

    Khodadoust, Saeid; Ghaedi, Mehrorang

    2014-12-10

    In this study a rapid and effective method (dispersive liquid-liquid microextraction (DLLME)) was developed for extraction of methyl red (MR) prior to its determination by UV-Vis spectrophotometry. Influence variables on DLLME such as volume of chloroform (as extractant solvent) and methanol (as dispersive solvent), pH and ionic strength and extraction time were investigated. Then significant variables were optimized by using a Box-Behnken design (BBD) and desirability function (DF). The optimized conditions (100μL of chloroform, 1.3mL of ethanol, pH 4 and 4% (w/v) NaCl) resulted in a linear calibration graph in the range of 0.015-10.0mgmL(-1) of MR in initial solution with R(2)=0.995 (n=5). The limits of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.015mgmL(-1), respectively. Finally, the DLLME method was applied for determination of MR in different water samples with relative standard deviation (RSD) less than 5% (n=5). Copyright © 2014 Elsevier B.V. All rights reserved.

  9. First Electrochemical Method of Nitrothal-Isopropyl Determination in Water Samples

    Directory of Open Access Journals (Sweden)

    Dariusz Guziejewski

    2016-01-01

    Full Text Available The aim of the research was the use of square wave adsorptive stripping voltammetry (SWAdSV in conjunction with a hanging mercury drop electrode (HMDE for the determination of nitrothal-isopropyl. It was found that optimal SW technique parameters were frequency, 200 Hz; amplitude, 50 mV; and step potential, 5 mV. Accumulation time and potential were studied to select the optimal conditions in adsorptive stripping voltammetry: 45 s at 0.0 V, respectively. The calibration curve (SWSV was linear in the nitrothal-isopropyl concentration range from 2.0 × 10−7 to 2.0 × 10−6 mol L−1 with detection limit of 3.46 × 10−8 mol L−1. The repeatability of the method was determined at a nitrothal-isopropyl concentration level equal to 6.0 × 10−7 mol L−1 and expressed as RSD = 5.5% (n=6. The proposed method was successfully validated by studying the recovery of nitrothal-isopropyl in spiked environmental samples.

  10. Application of response surface methodology for determination of methyl red in water samples by spectrophotometry method

    Science.gov (United States)

    Khodadoust, Saeid; Ghaedi, Mehrorang

    2014-12-01

    In this study a rapid and effective method (dispersive liquid-liquid microextraction (DLLME) was developed for extraction of methyl red (MR) prior to its determination by UV-Vis spectrophotometry. Influence variables on DLLME such as volume of chloroform (as extractant solvent) and methanol (as dispersive solvent), pH and ionic strength and extraction time were investigated. Then significant variables were optimized by using a Box-Behnken design (BBD) and desirability function (DF). The optimized conditions (100 μL of chloroform, 1.3 mL of ethanol, pH 4 and 4% (w/v) NaCl) resulted in a linear calibration graph in the range of 0.015-10.0 mg mL-1 of MR in initial solution with R2 = 0.995 (n = 5). The limits of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.015 mg mL-1, respectively. Finally, the DLLME method was applied for determination of MR in different water samples with relative standard deviation (RSD) less than 5% (n = 5).

  11. Determination of five nitroimidazole residues in artificial porcine muscle tissue samples by capillary electrophoresis.

    Science.gov (United States)

    Lin, Yingyun; Su, Yan; Liao, Xiulin; Yang, Na; Yang, Xiupei; Choi, Martin M F

    2012-01-15

    A capillary electrophoresis (CE) method with ultraviolet detection has been developed for simultaneous detection and quantification of five nitroimidazoles including benzoylmetronidazole, dimetridazole, metronidazole, ronidazole, and secnidazole in porcine muscles. Nitroimidazoles in samples were extracted by ethyl acetate with subsequent clean-up by a strong cation exchange solid phase extraction column. The clean extracts were subjected to CE separation with optimal experimental conditions: pH 3.0 running buffer containing 25mM sodium phosphate and 0.10mM tetrabutylammonium bromide, 5s hydrodynamic injection at 0.5psi and 28kV separation voltage. The nitroimidazoles could be monitored and detected at 320nm within 18min. The limits of detection were below 1.0μg/kg and limits of quantification were lower than 3.2μg/kg for all nitroimidazoles in the muscle samples. The recoveries and relative standard deviations were 85.4-96.0, 83.5-92.5, 1.3-3.9, and 1.1-4.2%, respectively for the intra-day and inter-day analyses. The proposed CE method has been successfully applied to determine nitroimidazoles in artificial porcine muscle samples with good accuracy and recovery, demonstrating that it has potential for detection and quantification of multi-nitroimidazole residue in real muscle samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Simultaneous Determination of Different Anions in Milk Samples Using Ion Chromatography with Conductivity Detection

    Directory of Open Access Journals (Sweden)

    Gülçin Gümüş Yılmaz

    2016-12-01

    Full Text Available The description of a simple method for simultaneous determination of chloride, nitrate, sulfate, iodide, phosphate, thiocyanate, perchlorate, and orotic acid in milk samples was outlined. The method involves the use of dialysis cassettes for matrix elimination, followed by ion chromatography on a high capacity anion exchange column with suppressed conductivity detection. The novelty of dialysis process was that it did not need any chemical and organic solvent for elimination of macromolecules such as fat, carbohydrates and proteins from milk samples. External standard calibration curves for these analytes were linear with great correlation coefficients. The relative standard deviations of analyte concentrations were acceptable both inter-day and intra-day evaluations. Under optimized conditions, the limit of detection (Signal-to-Noise ratio = 3 for chloride, phosphate, thiocyanate, perchlorate, iodide, nitrate, sulfate, and orotate was found to be 0.012, 0.112, 0.140, 0.280, 0.312, 0.516, 0.520, and 0.840 mg L−1, respectively. Significant results were obtained for various spiked milk samples with % recovery in the range of 93.88 - 109.75 %. The proposed method was successfully applied to milk samples collected from Istanbul markets. The advantages of the method described herein are reagent-free, simple, and reliable.

  13. Innovative sampling and extraction methods for the determination of nonsteroidal anti-inflammatory drugs in water.

    Science.gov (United States)

    Tanwar, Shivani; Di Carro, Marina; Magi, Emanuele

    2015-03-15

    Two different innovative approaches were used for the determination of nonsteroidal anti-inflammatory drugs (NSAIDs) in water: stir bar sorptive extraction (SBSE) and passive sampling, followed by electrospray ionization liquid chromatography-tandem mass spectrometry. SBSE was developed by comparing EG-Silicone and PDMS stir bars and optimizing main parameters to attain high preconcentration. Quantitative analysis was carried out by mass spectrometry in negative ionization mode and multiple reaction monitoring. The SBSE-LC-MS/MS method provided satisfactory figures of merit with LOD (7.5-71 ng L(-1)) and LOQ (22.5-213 ng L(-1)). The developed method was successfully applied to real samples collected from river water and wastewater effluents. The obtained results showed the presence of all analytes at trace levels, in a wide range of concentrations. The passive sampling approach was carried out by using Polar Organic Chemical Integrative Sampler (POCIS); samplers were deployed for 15 days in river and tap water, allowing to detect analytes at ultra-trace levels. Time-Weighted Average concentration of NSAIDs in river water was estimated in the range 0.33-0.46 ng L(-1), using the sampling rates previously obtained by means of a simple calibration system. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Influence of Sampling on the Determination of Warfarin and Warfarin Alcohols in Oral Fluid

    Science.gov (United States)

    Lomonaco, Tommaso; Ghimenti, Silvia; Piga, Isabella; Biagini, Denise; Onor, Massimo; Fuoco, Roger; Di Francesco, Fabio

    2014-01-01

    Background and Objective The determination of warfarin, RS/SR- and RR/SS-warfarin alcohols in oral fluid may offer additional information to the INR assay. This study aimed to establish an optimized sampling technique providing the best correlation between the oral fluid and the unbound plasma concentrations of these compounds. Materials and Methods Samples of non-stimulated and stimulated oral fluid, and blood were collected from 14 patients undergoing warfarin therapy. After acidification, analytes were extracted with a dichloromethane/hexane mixture and determined by HPLC with fluorescence detection. Plasma samples were also ultrafiltered for the determination of the unbound fraction. The chromatographic separation was carried out in isocratic conditions with a phosphate buffer/methanol mobile phase on a C-18 reversed-phase column. The absence of interfering compounds was verified by HPLC-ESI-Q-TOF. Results Stimulation generally increased the oral fluid pH to values close to blood pH in about 6 minutes. The concentration of warfarin and RS/SR-warfarin alcohols in oral fluid followed the same trend, whereas the concentration of RR/SS-warfarin alcohols was not affected. Six minute stimulation with chewing gum followed by collection with a polyester swab was the best sampling procedure, with a good repeatability (RSD warfarin (r  =  0.92, p warfarin alcohols (r  =  0.84, p warfarin (r  =  0.78, p warfarin alcohols (r  =  0.81, p warfarin and RS/SR-warfarin alcohols suggests that oral fluid analysis could provide clinically useful information for the monitoring of anticoagulant therapy, complementary to the INR assay. PMID:25478864

  15. Optimization and validation of Folin-Ciocalteu method for the determination of total polyphenol content of Pu-erh tea.

    Science.gov (United States)

    Musci, Marilena; Yao, Shicong

    2017-12-01

    Pu-erh tea is a post-fermented tea that has recently gained popularity worldwide, due to potential health benefits related to the antioxidant activity resulting from its high polyphenolic content. The Folin-Ciocalteu method is a simple, rapid, and inexpensive assay widely applied for the determination of total polyphenol content. Over the past years, it has been subjected to many modifications, often without any systematic optimization or validation. In our study, we sought to optimize the Folin-Ciocalteu method, evaluate quality parameters including linearity, precision and stability, and then apply the optimized model to determine the total polyphenol content of 57 Chinese teas, including green tea, aged and ripened Pu-erh tea. Our optimized Folin-Ciocalteu method reduced analysis time, allowed for the analysis of a large number of samples, to discriminate among the different teas, and to assess the effect of the post-fermentation process on polyphenol content.

  16. The determination of plutonium isotopes in environmental samples

    International Nuclear Information System (INIS)

    Siripirom, Lopchai.

    1983-01-01

    The concentration of plutonium in environmental samples such as soil, water, and surface air in the middle part of Thailand were studied. The surface air were collected only at the fifth floor of the Office of Atomic Energy for Peace (OAEP). Plutonium-242 was used as a tracer. Soil and air samples were dissolved by pyrosulphate fusion, and plutonium was co-precipitated with barium sulfate. Then dissolved the precipitate in perchloric acid. Plutonium was extracted out by using solvent bis-(2-ethylhexyl) phosphoric acid (HDEHP). Plutonium in water samples were coprecipitated with iron (III) hydroxide and were dissolved in 8 M. nitric acid. Then the plutonium was separated out by using anion exchange resin, Dowex 1x4. After the solvent extraction or the anion exchange, plutonium was coprecipitated with cerous hydroxide. The activities of plutonium were measured by a surface barrier detector for about 24 hours. Lower limit of detection for 1,440 minutes is 0.012 pCi. These studies showed that only plutonium-239, 240 was observed. The range of activities of plutonium-239, 240 in soil were 0.002-0.157 pCi/g (dry), in water were 0.1-81 f Ci/l, and in air were 7-330 a Ci/m 3 . However, the plutonium concentrations in these studies are far below the maximum permissible concentration (MPC) recommended by International Commission on Radiological Protection (ICRP) for general population which is equal to 3x10 8 f Ci/l of water and 5x10 6 a Ci/m 3 of air

  17. Determination of Cs-134 and Cs-137 rain water samples

    International Nuclear Information System (INIS)

    Lima, M.F.; Mazzilli, B.

    1988-01-01

    In order to setting an environmental monitoring program at IPEN, was developed a fast and simple methodology for concentration of Cs-134 and Cs-137 in rain water. This procedure consists in the precipitation of cesium and others cathions of its family (NH 4 + , K + and Rb + ) by ammonium molybdophosphate. The measures of the desintegration rates of Cs-134 and Cs-137 was done by gamma spectrometry in a Ge(Li) detector. After setting up the ideal experimental conditions, the procedure was used to analyze four samples of rain water. (author) [pt

  18. Spectrophotometric determination of vanadium in environmental and biological samples

    International Nuclear Information System (INIS)

    Rekha, D.; Krishnapriya, B.; Subrahmanyam, P.; Reddyprasad, P.; Dilip Kumar, J.; Chiranjeevi, P.

    2007-01-01

    The method is based on oxidation of p-nitro aniline by vanadium (V) followed by coupling reaction with N-(1-naphthalene-1-y1)ethane-1, 2-diaminedihydrochloride (NEDA) in basic medium of pH 8 to give purple colored derivative. The derivative having an λ max 525nm is stable for 10 days. Beer's law is obeyed for vanadium (V) in the concentration range of 0.03-4.5 μg ml -1 . The proposed method was successfully applied to the analysis of vanadium in environmental and biological samples. (author)

  19. Samplings of airborne particulates for granulometric determinations following Chernobyl accident

    International Nuclear Information System (INIS)

    Tarroni, G.; Calamosca, M.; Zaiacomo, T. de; Gragnani, R.; Michetti, I.; Testa, L.

    1988-01-01

    Particle size distributions and concentrations of the radioactive aerosol that arose from the Chernobyl accident were determined in Bologna and Rome. The activity Median Aerodynamic Diameters (AMAD) of Ru-103, Te-132, Cs-134 and Cs-137, determined by means of impactors, were in the range 0.8 - 1.4 μm with Geometric Standard Deviations (Sg) in the range 1.6 - 3.7. Lower AMAD and higher Sg values were found for I-131 compared to those for the other radioisotopes. The gaseous fraction of I-131 was 60-70% of the total aerosuspended activity of this isotope. A comparison between direct measurement data concerning internal contamination on volunteers and values derived from air contamination data shows that in Bologna, during May 1986, almost all the contamination was due to inhalation. The data are unable to distinguish between different inhalation models

  20. Optimization of the two-sample rank Neyman-Pearson detector

    Science.gov (United States)

    Akimov, P. S.; Barashkov, V. M.

    1984-10-01

    The development of optimal algorithms concerned with rank considerations in the case of finite sample sizes involves considerable mathematical difficulties. The present investigation provides results related to the design and the analysis of an optimal rank detector based on a utilization of the Neyman-Pearson criteria. The detection of a signal in the presence of background noise is considered, taking into account n observations (readings) x1, x2, ... xn in the experimental communications channel. The computation of the value of the rank of an observation is calculated on the basis of relations between x and the variable y, representing interference. Attention is given to conditions in the absence of a signal, the probability of the detection of an arriving signal, details regarding the utilization of the Neyman-Pearson criteria, the scheme of an optimal rank, multichannel, incoherent detector, and an analysis of the detector.

  1. Determination of the stoichiometric rate in UO2 samples

    International Nuclear Information System (INIS)

    Moura, Sergio C.; Lima, Nelson B. de; Sassine, Andre; Bustillos, Jose Oscar Vega

    2000-01-01

    The gravimetric and voltammetric methods for determination of non-stoichiometric O/U ratio in uranium dioxide used as nuclear fuel are discussed in this work. The oxidation of uranium oxide is very complex due to many phase changes. Gravimetric and voltammetric methods do not detect phase changes. The results of this work shown that, to evaluate both methods is requiring to be done Rietveld methods by X-ray diffraction data to identify the uranium oxide phase changes. (author)

  2. Fluorimetric routine determination of uranium in urine samples

    International Nuclear Information System (INIS)

    Widua, L.; Schieferdecker, H.; Hezel, U.

    With a modified RA 2 reflectance accessory for the Zeiss PMQII/PMQ3 spectrophotometer, uranium in urine was detected with higher sensitivity. A quick method is now available with a detection limit of <2 μg U/1 urine for the determination of possible uranium incorporations, whose sensitivity meets the requirements of radiation protection. Compared with other extraction methods, the instrument outlay and the required working time are small. The total error of the method is below 5 percent

  3. Radionuclide determination in environmental samples by inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Lariviere, Dominic; Taylor, Vivien F.; Evans, R. Douglas; Cornett, R. Jack

    2006-01-01

    The determination of naturally occurring and anthropogenic radionuclides in the environment by inductively coupled plasma mass spectrometry has gained recognition over the last fifteen years, relative to radiometric techniques, as the result of improvement in instrumental performance, sample introduction equipment, and sample preparation. With the increase in instrumental sensitivity, it is now possible to measure ultratrace levels (fg range) of many radioisotopes, including those with half-lives between 1 and 1000 years, without requiring very complex sample pre-concentration schemes. However, the identification and quantification of radioisotopes in environmental matrices is still hampered by a variety of analytical issues such as spectral (both atomic and molecular ions) and non-spectral (matrix effect) interferences and instrumental limitations (e.g., abundance sensitivity). The scope of this review is to highlight recent analytical progress and issues associated with the determination of radionuclides by inductively coupled plasma mass spectrometry. The impact of interferences, instrumental limitations (e.g., degree of ionization, abundance sensitivity, detection limits) and low sample-to-plasma transfer efficiency on the measurement of radionuclides by inductively coupled plasma mass spectrometry will be described. Solutions that overcome these issues will be discussed, highlighting their pros and cons and assessing their impact on the measurement of environmental radioactivity. Among the solutions proposed, mass and chemical resolution through the use of sector-field instruments and chemical reactions/collisions in a pressurized cell, respectively, will be described. Other methods, such as unique sample introduction equipment (e.g., laser ablation, electrothermal vaporisation, high efficiency nebulization) and instrumental modifications/optimizations (e.g., instrumental vacuum, radiofrequency power, guard electrode) that improve sensitivity and performance

  4. Determinants of renewable energy growth: A global sample analysis

    International Nuclear Information System (INIS)

    Aguirre, Mariana; Ibikunle, Gbenga

    2014-01-01

    We investigate factors influencing country-level renewable energy growth by applying FEVD and PCSE estimation methods in a unique sample analysis. With a longer time series (1990–2010) and a broader sample size of countries (including Brazil, Russia, India, China and South Africa) than previous studies, our results reveal new insights. The results suggest that certain government-backed energy policies impede renewable energy investments, thus implying significant failures in policy design. These policies may be failing mainly because of uncertainty and the likelihood of discontinuity. Weak voluntary approaches are introduced in order to satisfy public demand for more sustainable investments and programmes; we find that these may have negative influences on the growth of renewables as well. The insight gained is consistent over the estimation methods employed. - Highlights: • Some public energy policies are shown to impede renewable energy investments; this implies failure in policy design. • Environmental concern is shown to drive renewables investment but energy security concerns do not seem to influence renewables investment. • Results suggest that countries are likely to reduce renewables commitments when under pressure to ensure energy supply. • Results seem to underscore the policy lobbying strength of the traditional energy mix industries

  5. Determining Sample Size for Accurate Estimation of the Squared Multiple Correlation Coefficient.

    Science.gov (United States)

    Algina, James; Olejnik, Stephen

    2000-01-01

    Discusses determining sample size for estimation of the squared multiple correlation coefficient and presents regression equations that permit determination of the sample size for estimating this parameter for up to 20 predictor variables. (SLD)

  6. A novel variable selection approach that iteratively optimizes variable space using weighted binary matrix sampling.

    Science.gov (United States)

    Deng, Bai-chuan; Yun, Yong-huan; Liang, Yi-zeng; Yi, Lun-zhao

    2014-10-07

    In this study, a new optimization algorithm called the Variable Iterative Space Shrinkage Approach (VISSA) that is based on the idea of model population analysis (MPA) is proposed for variable selection. Unlike most of the existing optimization methods for variable selection, VISSA statistically evaluates the performance of variable space in each step of optimization. Weighted binary matrix sampling (WBMS) is proposed to generate sub-models that span the variable subspace. Two rules are highlighted during the optimization procedure. First, the variable space shrinks in each step. Second, the new variable space outperforms the previous one. The second rule, which is rarely satisfied in most of the existing methods, is the core of the VISSA strategy. Compared with some promising variable selection methods such as competitive adaptive reweighted sampling (CARS), Monte Carlo uninformative variable elimination (MCUVE) and iteratively retaining informative variables (IRIV), VISSA showed better prediction ability for the calibration of NIR data. In addition, VISSA is user-friendly; only a few insensitive parameters are needed, and the program terminates automatically without any additional conditions. The Matlab codes for implementing VISSA are freely available on the website: https://sourceforge.net/projects/multivariateanalysis/files/VISSA/.

  7. Determination of Pareto frontier in multi-objective maintenance optimization

    International Nuclear Information System (INIS)

    Certa, Antonella; Galante, Giacomo; Lupo, Toni; Passannanti, Gianfranco

    2011-01-01

    The objective of a maintenance policy generally is the global maintenance cost minimization that involves not only the direct costs for both the maintenance actions and the spare parts, but also those ones due to the system stop for preventive maintenance and the downtime for failure. For some operating systems, the failure event can be dangerous so that they are asked to operate assuring a very high reliability level between two consecutive fixed stops. The present paper attempts to individuate the set of elements on which performing maintenance actions so that the system can assure the required reliability level until the next fixed stop for maintenance, minimizing both the global maintenance cost and the total maintenance time. In order to solve the previous constrained multi-objective optimization problem, an effective approach is proposed to obtain the best solutions (that is the Pareto optimal frontier) among which the decision maker will choose the more suitable one. As well known, describing the whole Pareto optimal frontier generally is a troublesome task. The paper proposes an algorithm able to rapidly overcome this problem and its effectiveness is shown by an application to a case study regarding a complex series-parallel system.

  8. Sample preparation combined with electroanalysis to improve simultaneous determination of antibiotics in animal derived food samples.

    Science.gov (United States)

    da Silva, Wesley Pereira; de Oliveira, Luiz Henrique; Santos, André Luiz Dos; Ferreira, Valdir Souza; Trindade, Magno Aparecido Gonçalves

    2018-06-01

    A procedure based on liquid-liquid extraction (LLE) and phase separation using magnetically stirred salt-induced high-temperature liquid-liquid extraction (PS-MSSI-HT-LLE) was developed to extract and pre-concentrate ciprofloxacin (CIPRO) and enrofloxacin (ENRO) from animal food samples before electroanalysis. Firstly, simple LLE was used to extract the fluoroquinolones (FQs) from animal food samples, in which dilution was performed to reduce interference effects to below a tolerable threshold. Then, adapted PS-MSSI-HT-LLE protocols allowed re-extraction and further pre-concentration of target analytes in the diluted acid samples for simultaneous electrochemical quantification at low concentration levels. To improve the peak separation, in simultaneous detection, a baseline-corrected second-order derivative approach was processed. These approaches allowed quantification of target FQs from animal food samples spiked at levels of 0.80 to 2.00 µmol L -1 in chicken meat, with recovery values always higher than 80.5%, as well as in milk samples spiked at 4.00 µmol L -1 , with recovery values close to 70.0%. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Ionizing radiation as optimization method for aluminum detection from drinking water samples

    International Nuclear Information System (INIS)

    Bazante-Yamguish, Renata; Geraldo, Aurea Beatriz C.; Moura, Eduardo; Manzoli, Jose Eduardo

    2013-01-01

    The presence of organic compounds in water samples is often responsible for metal complexation; depending on the analytic method, the organic fraction may dissemble the evaluation of the real values of metal concentration. Pre-treatment of the samples is advised when organic compounds are interfering agents, and thus sample mineralization may be accomplished by several chemical and/or physical methods. Here, the ionizing radiation was used as an advanced oxidation process (AOP), for sample pre-treatment before the analytic determination of total and dissolved aluminum by ICP-OES in drinking water samples from wells and spring source located at Billings dam region. Before irradiation, the spring source and wells' samples showed aluminum levels of 0.020 mg/l and 0.2 mg/l respectively; after irradiation, both samples showed a 8-fold increase of aluminum concentration. These results are discussed considering other physical and chemical parameters and peculiarities of sample sources. (author)

  10. Determination of Sr-90 and Cs-137 in environmental samples

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    The comparison between the Ca concentration in the soil and the transfer factors involved indicates a clear dependence of Sr-90 soil-to-plant transport from the soil's Ca-content with the concentration level of 0.1 g Ca/kg soil appearing to be the limit level. Soil concentrations of Cs-137 determined to-date indicate a very even deposition density of Cs-137. The transfer factors of plant/soil in Chile differ but negligeably from those in Europe. (DG) [de

  11. Memory-Optimized Software Synthesis from Dataflow Program Graphs with Large Size Data Samples

    Directory of Open Access Journals (Sweden)

    Hyunok Oh

    2003-05-01

    Full Text Available In multimedia and graphics applications, data samples of nonprimitive type require significant amount of buffer memory. This paper addresses the problem of minimizing the buffer memory requirement for such applications in embedded software synthesis from graphical dataflow programs based on the synchronous dataflow (SDF model with the given execution order of nodes. We propose a memory minimization technique that separates global memory buffers from local pointer buffers: the global buffers store live data samples and the local buffers store the pointers to the global buffer entries. The proposed algorithm reduces 67% memory for a JPEG encoder, 40% for an H.263 encoder compared with unshared versions, and 22% compared with the previous sharing algorithm for the H.263 encoder. Through extensive buffer sharing optimization, we believe that automatic software synthesis from dataflow program graphs achieves the comparable code quality with the manually optimized code in terms of memory requirement.

  12. Optimization of liquid scintillation measurements applied to smears and aqueous samples collected in industrial environments

    Directory of Open Access Journals (Sweden)

    Arnaud Chapon

    Full Text Available Search for low-energy β contaminations in industrial environments requires using Liquid Scintillation Counting. This indirect measurement method supposes a fine control from sampling to measurement itself. Thus, in this paper, we focus on the definition of a measurement method, as generic as possible, for both smears and aqueous samples’ characterization. That includes choice of consumables, sampling methods, optimization of counting parameters and definition of energy windows, using the maximization of a Figure of Merit. Detection limits are then calculated considering these optimized parameters. For this purpose, we used PerkinElmer Tri-Carb counters. Nevertheless, except those relative to some parameters specific to PerkinElmer, most of the results presented here can be extended to other counters. Keywords: Liquid Scintillation Counting (LSC, PerkinElmer, Tri-Carb, Smear, Swipe

  13. The SDSS-IV MaNGA Sample: Design, Optimization, and Usage Considerations

    Science.gov (United States)

    Wake, David A.; Bundy, Kevin; Diamond-Stanic, Aleksandar M.; Yan, Renbin; Blanton, Michael R.; Bershady, Matthew A.; Sánchez-Gallego, José R.; Drory, Niv; Jones, Amy; Kauffmann, Guinevere; Law, David R.; Li, Cheng; MacDonald, Nicholas; Masters, Karen; Thomas, Daniel; Tinker, Jeremy; Weijmans, Anne-Marie; Brownstein, Joel R.

    2017-09-01

    We describe the sample design for the SDSS-IV MaNGA survey and present the final properties of the main samples along with important considerations for using these samples for science. Our target selection criteria were developed while simultaneously optimizing the size distribution of the MaNGA integral field units (IFUs), the IFU allocation strategy, and the target density to produce a survey defined in terms of maximizing signal-to-noise ratio, spatial resolution, and sample size. Our selection strategy makes use of redshift limits that only depend on I-band absolute magnitude (M I ), or, for a small subset of our sample, M I and color (NUV - I). Such a strategy ensures that all galaxies span the same range in angular size irrespective of luminosity and are therefore covered evenly by the adopted range of IFU sizes. We define three samples: the Primary and Secondary samples are selected to have a flat number density with respect to M I and are targeted to have spectroscopic coverage to 1.5 and 2.5 effective radii (R e ), respectively. The Color-Enhanced supplement increases the number of galaxies in the low-density regions of color-magnitude space by extending the redshift limits of the Primary sample in the appropriate color bins. The samples cover the stellar mass range 5× {10}8≤slant {M}* ≤slant 3× {10}11 {M}⊙ {h}-2 and are sampled at median physical resolutions of 1.37 and 2.5 kpc for the Primary and Secondary samples, respectively. We provide weights that will statistically correct for our luminosity and color-dependent selection function and IFU allocation strategy, thus correcting the observed sample to a volume-limited sample.

  14. Sample-Path Optimal Stationary Policies in Stable Markov Decision Chains with Average Reward Criterion

    Czech Academy of Sciences Publication Activity Database

    Cavazos-Cadena, R.; Montes-de-Oca, R.; Sladký, Karel

    2015-01-01

    Roč. 52, č. 2 (2015), s. 419-440 ISSN 0021-9002 Grant - others:GA AV ČR(CZ) 171396 Institutional support: RVO:67985556 Keywords : Dominated Convergence theorem for the expected average criterion * Discrepancy function * Kolmogorov inequality * Innovations * Strong sample-path optimality Subject RIV: BC - Control Systems Theory Impact factor: 0.665, year: 2015 http://library.utia.cas.cz/separaty/2015/E/sladky-0449029.pdf

  15. Determination of 35S-aminoacyl-transfer ribonucleic acid specific radioactivity in small tissue samples

    International Nuclear Information System (INIS)

    Samarel, A.M.; Ogunro, E.A.; Ferguson, A.G.; Lesch, M.

    1981-01-01

    Rate determination of protein synthesis utilizing tracer amino acid incorporation requires accurate assessment of the specific radioactivity of the labeled precursor aminoacyl-tRNA pool. Previously published methods presumably useful for the measurement of any aminoacyl-tRNA were unsuccessful when applied to [ 35 S]methionine, due to the unique chemical properties of this amino acid. Herein we describe modifications of these methods necessary for the measurement of 35 S-aminoacyl-tRNA specific radioactivity from small tissue samples incubated in the presence of [ 35 S]methionine. The use of [ 35 S]methionine of high specific radioactivity enables analysis of the methionyl-tRNA from less than 100 mg of tissue. Conditions for optimal recovery of 35 S-labeled dansyl-amino acid derivatives are presented and possible applications of this method are discussed

  16. Determination of /sup 35/S-aminoacyl-transfer ribonucleic acid specific radioactivity in small tissue samples

    Energy Technology Data Exchange (ETDEWEB)

    Samarel, A.M.; Ogunro, E.A.; Ferguson, A.G.; Lesch, M.

    1981-11-15

    Rate determination of protein synthesis utilizing tracer amino acid incorporation requires accurate assessment of the specific radioactivity of the labeled precursor aminoacyl-tRNA pool. Previously published methods presumably useful for the measurement of any aminoacyl-tRNA were unsuccessful when applied to (/sup 35/S)methionine, due to the unique chemical properties of this amino acid. Herein we describe modifications of these methods necessary for the measurement of /sup 35/S-aminoacyl-tRNA specific radioactivity from small tissue samples incubated in the presence of (/sup 35/S)methionine. The use of (/sup 35/S)methionine of high specific radioactivity enables analysis of the methionyl-tRNA from less than 100 mg of tissue. Conditions for optimal recovery of /sup 35/S-labeled dansyl-amino acid derivatives are presented and possible applications of this method are discussed.

  17. NGSI FY15 Final Report. Innovative Sample Preparation for in-Field Uranium Isotopic Determinations

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Thomas M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Meyers, Lisa [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-10

    Our FY14 Final Report included an introduction to the project, background, literature search of uranium dissolution methods, assessment of commercial off the shelf (COTS) automated sample preparation systems, as well as data and results for dissolution of bulk quantities of uranium oxides, and dissolution of uranium oxides from swipe filter materials using ammonium bifluoride (ABF). Also, discussed were reaction studies of solid ABF with uranium oxide that provided a basis for determining the ABF/uranium oxide dissolution mechanism. This report details the final experiments for optimizing dissolution of U3O8 and UO2 using ABF and steps leading to development of a Standard Operating Procedure (SOP) for dissolution of uranium oxides on swipe filters.

  18. Unit Stratified Sampling as a Tool for Approximation of Stochastic Optimization Problems

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Martin

    2012-01-01

    Roč. 19, č. 30 (2012), s. 153-169 ISSN 1212-074X R&D Projects: GA ČR GAP402/11/0150; GA ČR GAP402/10/0956; GA ČR GA402/09/0965 Institutional research plan: CEZ:AV0Z10750506 Institutional support: RVO:67985556 Keywords : Stochastic programming * approximation * stratified sampling Subject RIV: BB - Applied Statistics, Operational Research http://library.utia.cas.cz/separaty/2013/E/smid-unit stratified sampling as a tool for approximation of stochastic optimization problems.pdf

  19. A novel visible spectrophotometric method for the determination of ethamsylate in pharmaceutical preparations and biological samples

    Science.gov (United States)

    Zhang, Meiyun; Zhang, Yan; Li, Quanmin

    2010-03-01

    A highly sensitive visible spectrophotometric method has been developed to determine ethamsylate in this paper, which is based on using Cu(II) as spectroscopic probe reagent. The study indicates that in the presence of SCN - and KNO 3, Cu(II) is reduced to Cu(I) by ethamsylate at pH 5.0, and the in situ formed Cu(I) reacts with SCN - to form into the white emulsion CuSCN that could be stayed upon the surface of water. According to the amount of residual Cu(II), the amount of ethamsylate can be indirectly determined. Under the optimal conditions, Beer's law is applicable in the range of 0.2-9.0 μg/mL (7.60 × 10 -7-3.42 × 10 -5 mol/L) for aqueous standard solution of ethamsylate with linear correlation coefficient of 0.9998. The detection limit and relative standard deviation are 0.12 μg/mL and 1.5%, respectively. And the molar absorption coefficient of the indirect determination of ethamsylate is 1.0 × 10 5 L/mol cm. The method is successfully applied to determine ethamsylate in pharmaceutical preparations and biological samples.

  20. Generalized Likelihood Uncertainty Estimation (GLUE) Using Multi-Optimization Algorithm as Sampling Method

    Science.gov (United States)

    Wang, Z.

    2015-12-01

    For decades, distributed and lumped hydrological models have furthered our understanding of hydrological system. The development of hydrological simulation in large scale and high precision elaborated the spatial descriptions and hydrological behaviors. Meanwhile, the new trend is also followed by the increment of model complexity and number of parameters, which brings new challenges of uncertainty quantification. Generalized Likelihood Uncertainty Estimation (GLUE) has been widely used in uncertainty analysis for hydrological models referring to Monte Carlo method coupled with Bayesian estimation. However, the stochastic sampling method of prior parameters adopted by GLUE appears inefficient, especially in high dimensional parameter space. The heuristic optimization algorithms utilizing iterative evolution show better convergence speed and optimality-searching performance. In light of the features of heuristic optimization algorithms, this study adopted genetic algorithm, differential evolution, shuffled complex evolving algorithm to search the parameter space and obtain the parameter sets of large likelihoods. Based on the multi-algorithm sampling, hydrological model uncertainty analysis is conducted by the typical GLUE framework. To demonstrate the superiority of the new method, two hydrological models of different complexity are examined. The results shows the adaptive method tends to be efficient in sampling and effective in uncertainty analysis, providing an alternative path for uncertainty quantilization.

  1. Sterile Reverse Osmosis Water Combined with Friction Are Optimal for Channel and Lever Cavity Sample Collection of Flexible Duodenoscopes

    Directory of Open Access Journals (Sweden)

    Michelle J. Alfa

    2017-11-01

    Full Text Available IntroductionSimulated-use buildup biofilm (BBF model was used to assess various extraction fluids and friction methods to determine the optimal sample collection method for polytetrafluorethylene channels. In addition, simulated-use testing was performed for the channel and lever cavity of duodenoscopes.Materials and methodsBBF was formed in polytetrafluorethylene channels using Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Sterile reverse osmosis (RO water, and phosphate-buffered saline with and without Tween80 as well as two neutralizing broths (Letheen and Dey–Engley were each assessed with and without friction. Neutralizer was added immediately after sample collection and samples concentrated using centrifugation. Simulated-use testing was done using TJF-Q180V and JF-140F Olympus duodenoscopes.ResultsDespite variability in the bacterial CFU in the BBF model, none of the extraction fluids tested were significantly better than RO. Borescope examination showed far less residual material when friction was part of the extraction protocol. The RO for flush-brush-flush (FBF extraction provided significantly better recovery of E. coli (p = 0.02 from duodenoscope lever cavities compared to the CDC flush method.Discussion and conclusionWe recommend RO with friction for FBF extraction of the channel and lever cavity of duodenoscopes. Neutralizer and sample concentration optimize recovery of viable bacteria on culture.

  2. Challenging genosensors in food samples: The case of gluten determination in highly processed samples.

    Science.gov (United States)

    Martín-Fernández, Begoña; de-los-Santos-Álvarez, Noemí; Martín-Clemente, Juan Pedro; Lobo-Castañón, María Jesús; López-Ruiz, Beatriz

    2016-01-01

    Electrochemical genosensors have undergone an enormous development in the last decades, but only very few have achieved a quantification of target content in highly processed food samples. The detection of allergens, and particularly gluten, is challenging because legislation establishes a threshold of 20 ppm for labeling as gluten-free but most genosensors expresses the results in DNA concentration or DNA copies. This paper describes the first attempt to correlate the genosensor response and the wheat content in real samples, even in the case of highly processed food samples. A sandwich-based format, comprising a capture probe immobilized onto the screen-printed gold electrode, and a signaling probe functionalized with fluorescein isothiocyanate (FITC), both hybridizing with the target was used. The hybridization event was electrochemically monitored by adding an anti-FITC peroxidase (antiFITC-HRP) and its substrate, tetramethylbenzidine. Binary model mixtures, as a reference material, and real samples have been analyzed. DNA from food was extracted and a fragment encoding the immunodominant peptide of α2-gliadin amplified by a tailored PCR. The sensor was able to selectively detect toxic cereals for celiac patients, such as different varieties of wheat, barley, rye and oats, from non-toxic plants. As low as 0.001% (10 mg/kg) of wheat flour in an inert matrix was reliably detected, which directly compete with the current method of choice for DNA detection, the real-time PCR. A good correlation with the official immunoassay was found in highly processed food samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Direct determination of trace rare earth elements in ancient porcelain samples with slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Xiang Guoqiang; Jiang Zucheng; He Man; Hu Bin

    2005-01-01

    A method for the direct determination of trace rare earth elements in ancient porcelain samples by slurry sampling fluorinating electrothermal vaporization inductively coupled plasma mass spectrometry was developed with the use of polytetrafluoroethylene as fluorinating reagent. It was found that Si, as a main matrix element in ancient porcelain sample, could be mostly removed at the ashing temperature of 1200 deg. C without considerable losses of the analytes. However, the chemical composition of ancient porcelain sample is very complicated, which makes the influences resulting from other matrix elements not be ignored. Therefore, the matrix effect of ancient porcelain sample was also investigated, and it was found that the matrix effect is obvious when the matrix concentration was larger than 0.8 g l -1 . The study results of particle size effect indicated that when the sample particle size was less than 0.057 mm, the particle size effect is negligible. Under the optimized operation conditions, the detection limits for rare earth elements by fluorinating electrothermal vaporization inductively coupled plasma mass spectrometry were 0.7 ng g -1 (Eu)-33.3 ng g -1 (Nd) with the precisions of 4.1% (Yb)-10% (La) (c = 1 μg l -1 , n = 9). The proposed method was used to directly determine the trace rare earth elements in ancient porcelain samples produced in different dynasty (Sui, Ming and Qing), and the analytical results are satisfactory

  4. Optimization and determination of polycyclic aromatic hydrocarbons in biochar-based fertilizers.

    Science.gov (United States)

    Chen, Ping; Zhou, Hui; Gan, Jay; Sun, Mingxing; Shang, Guofeng; Liu, Liang; Shen, Guoqing

    2015-03-01

    The agronomic benefit of biochar has attracted widespread attention to biochar-based fertilizers. However, the inevitable presence of polycyclic aromatic hydrocarbons in biochar is a matter of concern because of the health and ecological risks of these compounds. The strong adsorption of polycyclic aromatic hydrocarbons to biochar complicates their analysis and extraction from biochar-based fertilizers. In this study, we optimized and validated a method for determining the 16 priority polycyclic aromatic hydrocarbons in biochar-based fertilizers. Results showed that accelerated solvent extraction exhibited high extraction efficiency. Based on a Box-Behnken design with a triplicate central point, accelerated solvent extraction was used under the following optimal operational conditions: extraction temperature of 78°C, extraction time of 17 min, and two static cycles. The optimized method was validated by assessing the linearity of analysis, limit of detection, limit of quantification, recovery, and application to real samples. The results showed that the 16 polycyclic aromatic hydrocarbons exhibited good linearity, with a correlation coefficient of 0.996. The limits of detection varied between 0.001 (phenanthrene) and 0.021 mg/g (benzo[ghi]perylene), and the limits of quantification varied between 0.004 (phenanthrene) and 0.069 mg/g (benzo[ghi]perylene). The relative recoveries of the 16 polycyclic aromatic hydrocarbons were 70.26-102.99%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Potentiometric determination of hexavalent uranium in uranium silicide samples

    International Nuclear Information System (INIS)

    Arlegui, Oscar

    1999-01-01

    The Chilean Nuclear Energy Commission's Department of Nuclear Materials has among its projects the production of fuels elements for nuclear reactors, and, therefore, the Chemical Analysis Laboratory must have a rapid and reliable method for uranium analysis, to control the uranium concentration during each stage of the production process. For this reason the Chilean Nuclear Energy Commission's Chemical Analysis Laboratory has validated a potentiometric method, which is a modification of the Davies and Gray method proposed by A.R. Eberle. This method uses the Potentiometric Titration Technique and is based on the direct and rapid reduction of uranium (VI) to Uranium (IV), in a concentrated phosphoric acid medium, with excess iron (II) used as a reducing agent. In this medium the excess iron (II) selectively oxidizes to iron (III) with nitric acid, using molybdenum (IV) as a catalyzer, the nitrous acid that is produced is eliminated by adding amidosulfuric acid. The solution is diluted with 1M sulfuric acid and the uranium (IV) obtained is titrated potentiometrically with potassium dichromate in the presence of vanadilic sulfate to obtain a better defined final titration point. The samples were softened with hydrochloric acid and nitric acid and later 50 ml were estimated in a 20% sulfuric acid medium. The analytical method was validated by comparing it with Certified Reference Material (C.R.M.) from the New Brunswick Laboratory (NBL), Metallic Uranium, CRM 112-A. The F Test and the T Test show that the value calculated is less than the tabulated value so the result is traceable to the reference material. The quantification limit, sensitivity, precision and accuracy were quantified for the method

  6. Determine the Quality of Bread Samples Used in Qazvin, Iran

    Directory of Open Access Journals (Sweden)

    Peyman Qajarbeygi

    2018-04-01

    Full Text Available In most societies, rich and important source of food considered bread. Some bakeries using sodium bicarbonate as baking soda and extra salt in bread production that his chemical compounds has adverse effects on the public health. That's why in this study we decided to evaluation of In most societies, rich and important source of food considered bread. Some bakeries using sodium bicarbonate as baking soda and extra salt in bread production that his chemical compounds has adverse effects on the public health. That's why in this study we decided to evaluation of produced bread in Qazvin province in terms of sodium bicarbonate and salt. Assessment of pH and salt take place according to Institute of Standards and Industrial Research of Iran (IRIS. Our Results demonstrated the mean±SD of pH for sangak, lavash, taftun, barbari and baguette 5.95±0.37, 5.76±0.54, 5.80±0.71, 6.10±0.68 and 7.86±1.26 respectively, and the mean±SD of salt 1.10±0.47, 1.41±0.57, 1.45±0.36, 1.40±0.32 and 1.55±1.09 respectively and the results demonstrated the value of pH and salt in the samples 65.77% (98 out of 149 and 12.75% (130 out of 149 respectively, out of standard range. Baking Soda in sangak breads and salt in baguette breads, more common of other breads. Although the Ministry of Health has banned officially the use of baking soda in breads production process, but demonstrated in this study baking soda and extra salt used in the process of breads production. Thus require more supervision and training on the non-use of sodium bicarbonate for bakers its necessary.

  7. Application of ion mobility spectrometry for the determination of tramadol in biological samples

    Directory of Open Access Journals (Sweden)

    Ali Sheibani

    2014-12-01

    Full Text Available In this study, a simple and rapid ion mobility spectrometry (IMS method has been described for the determination of tramadol. The operating instrumental parameters that could influence IMS were investigated and optimized (temperature; injection: 220 and IMS cell: 190°C, flow rate; carrier: 300 and drift: 600 mL/minute, voltage; corona: 2300 and drift: 7000 V, pulse width: 100 μs. Under optimum conditions, the calibration curves were linear within two orders of magnitude with R2 ≥ 0.998 for the determination of tramadol in human plasma, saliva, serum, and urine samples. The limits of detection and the limits of quantitation were between 0.1 and 0.3 and 0.3 and 1 ng/mL, respectively. The relative standard deviations were between 7.5 and 8.8%. The recovery results (90–103.9% indicate that the proposed method can be applied for tramadol analysis in different biological samples.

  8. A multisyringe flow injection method for the determination of thorium in water samples using spectrophotometric detection

    International Nuclear Information System (INIS)

    Guzman-Mar, J.L.; Aracely Hernandez-Ramirez; Lopez-Chuken, U.J.; Lopez-de-Alba, P.L.; Victor Cerda

    2011-01-01

    A fast and simple multisyringe flow injection analysis (MSFIA) method for routine determination of thorium in water samples was developed. The methodology was based on the complexation reaction of thorium with arsenazo (III) at pH 2.0. Thorium concentrations were spectrophotometrically detected at 665 nm. Under optimal conditions, Beer's law was obeyed over the range from 0.2 to 4.5 μg mL -1 thorium, a 3σ detection limit of 0.05 μg mL -1 , and a 10σ quantification limit of 0.2 μg mL -1 were obtained. The relative standard deviations (RSD, %) at 0.5, 2.5 and 4.5 μg mL -1 was 2.8, 1.5 and 0.8%, respectively (n = 10). It was found that most of the common metal ions and anions did not interfere with the thorium determination. The proposed method was successfully applied to its analysis in various water samples. (author)

  9. Matrix-assisted laser desorption/ionization sample preparation optimization for structural characterization of poly(styrene-co-pentafluorostyrene) copolymers

    International Nuclear Information System (INIS)

    Tisdale, Evgenia; Kennedy, Devin; Wilkins, Charles

    2014-01-01

    Graphical abstract: -- Highlights: •We optimized sample preparation for MALDI TOF poly(styrene-copentafluorostyrene) co-polymers. •Influence of matrix choice was investigated. •Influence of matrix/analyte ratio was examined. •Influence of analyte/salt ratio (for Ag+ salt) was studied. -- Abstract: The influence of the sample preparation parameters (the choice of the matrix, matrix:analyte ratio, salt:analyte ratio) was investigated and optimal conditions were established for the MALDI time-of-flight mass spectrometry analysis of the poly(styrene-co-pentafluorostyrene) copolymers. These were synthesized by atom transfer radical polymerization. Use of 2,5-dihydroxybenzoic acid as matrix resulted in spectra with consistently high ion yields for all matrix:analyte:salt ratios tested. The optimized MALDI procedure was successfully applied to the characterization of three copolymers obtained by varying the conditions of polymerization reaction. It was possible to establish the nature of the end groups, calculate molecular weight distributions, and determine the individual length distributions for styrene and pentafluorostyrene monomers, contained in the resulting copolymers. Based on the data obtained, it was concluded that individual styrene chain length distributions are more sensitive to the change in the composition of the catalyst (the addition of small amount of CuBr 2 ) than is the pentafluorostyrene component distribution

  10. Matrix-assisted laser desorption/ionization sample preparation optimization for structural characterization of poly(styrene-co-pentafluorostyrene) copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Tisdale, Evgenia; Kennedy, Devin; Wilkins, Charles, E-mail: cwilkins@uark.edu

    2014-01-15

    Graphical abstract: -- Highlights: •We optimized sample preparation for MALDI TOF poly(styrene-copentafluorostyrene) co-polymers. •Influence of matrix choice was investigated. •Influence of matrix/analyte ratio was examined. •Influence of analyte/salt ratio (for Ag+ salt) was studied. -- Abstract: The influence of the sample preparation parameters (the choice of the matrix, matrix:analyte ratio, salt:analyte ratio) was investigated and optimal conditions were established for the MALDI time-of-flight mass spectrometry analysis of the poly(styrene-co-pentafluorostyrene) copolymers. These were synthesized by atom transfer radical polymerization. Use of 2,5-dihydroxybenzoic acid as matrix resulted in spectra with consistently high ion yields for all matrix:analyte:salt ratios tested. The optimized MALDI procedure was successfully applied to the characterization of three copolymers obtained by varying the conditions of polymerization reaction. It was possible to establish the nature of the end groups, calculate molecular weight distributions, and determine the individual length distributions for styrene and pentafluorostyrene monomers, contained in the resulting copolymers. Based on the data obtained, it was concluded that individual styrene chain length distributions are more sensitive to the change in the composition of the catalyst (the addition of small amount of CuBr{sub 2}) than is the pentafluorostyrene component distribution.

  11. Development of Radioanalytical and Microanalytical Procedures for the Determination of Actinides in Environmental Samples

    International Nuclear Information System (INIS)

    Macsik, Zsuzsanna; Vajda, Nora; Bene, Balazs; Varga, Zsolt

    2008-01-01

    A radio-analytical procedure has been developed for the simultaneous determination of actinides in swipe samples by alpha-spectrometry after the separation of the actinides by extraction chromatography. The procedure is based on the complete decomposition of the sample by destruction with microwave digestion or ashing in furnace. Actinides are separated on an extraction chromatographic column filled with TRU resin (product of Eichrom Industries Inc.). Alpha sources prepared from the separated fractions of americium, plutonium, thorium and uranium are counted by alpha spectrometry. Micro-analytical procedure is being developed for the location and identification of individual particles containing fissile material using solid state nuclear track detectors. The parameters of alpha and fission track detection have been optimized and a procedure has been elaborated to locate the particles on the sample by defining the coordinates of the tracks created by the particles on the track detector. Development of a procedure is planned to separate the located particles using micromanipulator and these particles will be examined individually by different micro- and radio-analytical techniques. (authors)

  12. Determination of methylmercury in marine biota samples with advanced mercury analyzer: method validation.

    Science.gov (United States)

    Azemard, Sabine; Vassileva, Emilia

    2015-06-01

    In this paper, we present a simple, fast and cost-effective method for determination of methyl mercury (MeHg) in marine samples. All important parameters influencing the sample preparation process were investigated and optimized. Full validation of the method was performed in accordance to the ISO-17025 (ISO/IEC, 2005) and Eurachem guidelines. Blanks, selectivity, working range (0.09-3.0ng), recovery (92-108%), intermediate precision (1.7-4.5%), traceability, limit of detection (0.009ng), limit of quantification (0.045ng) and expanded uncertainty (15%, k=2) were assessed. Estimation of the uncertainty contribution of each parameter and the demonstration of traceability of measurement results was provided as well. Furthermore, the selectivity of the method was studied by analyzing the same sample extracts by advanced mercury analyzer (AMA) and gas chromatography-atomic fluorescence spectrometry (GC-AFS). Additional validation of the proposed procedure was effectuated by participation in the IAEA-461 worldwide inter-laboratory comparison exercises. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Development of Radioanalytical and Microanalytical Procedures for the Determination of Actinides in Environmental Samples

    Energy Technology Data Exchange (ETDEWEB)

    Macsik, Zsuzsanna [Institute of Nuclear Techniques, Moegyetem rakpart 9, H-1111 Budapest (Hungary); Vajda, Nora [RadAnal Ltd., Bimbo ut 119/a, H-1026 Budapest (Hungary); Bene, Balazs [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Varga, Zsolt [Institute of Isotopes, Konkoly-Thege M. ut 29-33, H-1121 Budapest (Hungary)

    2008-07-01

    A radio-analytical procedure has been developed for the simultaneous determination of actinides in swipe samples by alpha-spectrometry after the separation of the actinides by extraction chromatography. The procedure is based on the complete decomposition of the sample by destruction with microwave digestion or ashing in furnace. Actinides are separated on an extraction chromatographic column filled with TRU resin (product of Eichrom Industries Inc.). Alpha sources prepared from the separated fractions of americium, plutonium, thorium and uranium are counted by alpha spectrometry. Micro-analytical procedure is being developed for the location and identification of individual particles containing fissile material using solid state nuclear track detectors. The parameters of alpha and fission track detection have been optimized and a procedure has been elaborated to locate the particles on the sample by defining the coordinates of the tracks created by the particles on the track detector. Development of a procedure is planned to separate the located particles using micromanipulator and these particles will be examined individually by different micro- and radio-analytical techniques. (authors)

  14. Determination methods of the 90Sr in a sample of contaminated water

    International Nuclear Information System (INIS)

    Ometakova, J.; Silvia Dulanska, S.

    2009-01-01

    The aim of this work was a comparison of selected products from the point of view of the amount of strontium yields, time needed and possibility of multiple use of sorbents. Three commercial products: 3M Empore Stroncium Rad Disk, AnaLig , Sr-Resin and two classical methods: liquid-liquid extraction with tributylphosphate and carbonate coprecipitation (to eliminate interferents) were used for separation of 90 Sr. The model sample was used in radiochemical analysis to check multiple use of 3M Em-pore Stroncium Rad Disk a AnaLig. A radiochemical strontium yield was traced by using radionuclide 85 Sr. The model sample was also used to optimize conditions of strontium separation. The results were used for 90 Sr determination from a sample of permeating groundwater from a supervised zone of a Nuclear Power Plant Jaslovske Bohunice. We have found out that 90 Sr separation with sorbents AnaLig Sr-01, 3M Empore Sr Rad Disk is as effective as with sorbent Sr-Resin in matrices of contaminated water. (authors)

  15. Optimized determination of the radiological inventory during different phases of decommissioning

    International Nuclear Information System (INIS)

    Hillberg, Matthias; Beltz, Detlef; Karschnick, Oliver

    2012-01-01

    The decommissioning of nuclear facilities comprises a lot of activities such as decontamination, dismantling and demolition of equipment and structures. For these activities the aspects of health and safety of the operational personnel and of the general public as well as the minimization of radioactive waste have to be taken into account. An optimized, comprehensible and verifiable determination of the radiological inventory is essential for the decommissioning management with respect to safety, time, and costs. For example: right from the start of the post operational phase, the radiological characterization has to enable the decision whether to perform a system decontamination or not. Furthermore it is necessary, e.g. to determine the relevant nuclides and their composition (nuclide vector) for the release of material and for sustaining the radiological health and safety at work (e. g. minimizing the risk of incorporation). Our contribution will focus on the optimization of the radiological characterization with respect to the requisite extent and the best instant of time during the decommissioning process. For example: which additional information, besides the history of operation, is essential for an adequate amount of sampling and measurements needed in order to determine the relevant nuclides and their compositions? Furthermore, the characterization of buildings requires a kind of a graded approach during the decommissioning process. At the beginning of decommissioning, only a rough estimate of the expected radioactive waste due to the necessary decontamination of the building structures is sufficient. With ongoing decommissioning, a more precise radiological characterization of buildings is needed in order to guarantee an optimized, comprehensible and verifiable decontamination, dismantling and trouble-free clearance. These and other examples will be discussed on the background of and with reference to different decommissioning projects involving direct

  16. SU-E-T-21: A Novel Sampling Algorithm to Reduce Intensity-Modulated Radiation Therapy (IMRT) Optimization Time

    International Nuclear Information System (INIS)

    Tiwari, P; Xie, Y; Chen, Y; Deasy, J

    2014-01-01

    Purpose: The IMRT optimization problem requires substantial computer time to find optimal dose distributions because of the large number of variables and constraints. Voxel sampling reduces the number of constraints and accelerates the optimization process, but usually deteriorates the quality of the dose distributions to the organs. We propose a novel sampling algorithm that accelerates the IMRT optimization process without significantly deteriorating the quality of the dose distribution. Methods: We included all boundary voxels, as well as a sampled fraction of interior voxels of organs in the optimization. We selected a fraction of interior voxels using a clustering algorithm, that creates clusters of voxels that have similar influence matrix signatures. A few voxels are selected from each cluster based on the pre-set sampling rate. Results: We ran sampling and no-sampling IMRT plans for de-identified head and neck treatment plans. Testing with the different sampling rates, we found that including 10% of inner voxels produced the good dose distributions. For this optimal sampling rate, the algorithm accelerated IMRT optimization by a factor of 2–3 times with a negligible loss of accuracy that was, on average, 0.3% for common dosimetric planning criteria. Conclusion: We demonstrated that a sampling could be developed that reduces optimization time by more than a factor of 2, without significantly degrading the dose quality

  17. Model for determining and optimizing delivery performance in industrial systems

    Directory of Open Access Journals (Sweden)

    Fechete Flavia

    2017-01-01

    Full Text Available Performance means achieving organizational objectives regardless of their nature and variety, and even overcoming them. Improving performance is one of the major goals of any company. Achieving the global performance means not only obtaining the economic performance, it is a must to take into account other functions like: function of quality, delivery, costs and even the employees satisfaction. This paper aims to improve the delivery performance of an industrial system due to their very low results. The delivery performance took into account all categories of performance indicators, such as on time delivery, backlog efficiency or transport efficiency. The research was focused on optimizing the delivery performance of the industrial system, using linear programming. Modeling the delivery function using linear programming led to obtaining precise quantities to be produced and delivered each month by the industrial system in order to minimize their transport cost, satisfying their customers orders and to control their stock. The optimization led to a substantial improvement in all four performance indicators that concern deliveries.

  18. Transverse micro-erosion meter measurements; determining minimum sample size

    Science.gov (United States)

    Trenhaile, Alan S.; Lakhan, V. Chris

    2011-11-01

    Two transverse micro-erosion meter (TMEM) stations were installed in each of four rock slabs, a slate/shale, basalt, phyllite/schist, and sandstone. One station was sprayed each day with fresh water and the other with a synthetic sea water solution (salt water). To record changes in surface elevation (usually downwearing but with some swelling), 100 measurements (the pilot survey), the maximum for the TMEM used in this study, were made at each station in February 2010, and then at two-monthly intervals until February 2011. The data were normalized using Box-Cox transformations and analyzed to determine the minimum number of measurements needed to obtain station means that fall within a range of confidence limits of the population means, and the means of the pilot survey. The effect on the confidence limits of reducing an already small number of measurements (say 15 or less) is much greater than that of reducing a much larger number of measurements (say more than 50) by the same amount. There was a tendency for the number of measurements, for the same confidence limits, to increase with the rate of downwearing, although it was also dependent on whether the surface was treated with fresh or salt water. About 10 measurements often provided fairly reasonable estimates of rates of surface change but with fairly high percentage confidence intervals in slowly eroding rocks; however, many more measurements were generally needed to derive means within 10% of the population means. The results were tabulated and graphed to provide an indication of the approximate number of measurements required for given confidence limits, and the confidence limits that might be attained for a given number of measurements.

  19. Determinants of Optimal Adherence to Antiretroviral Therapy among ...

    African Journals Online (AJOL)

    SITWALA COMPUTERS

    medication side effects and adolescence were associated with non-adherence (p ... especially the social determinants of health surrounding ... irrespective of their CD4 cell count. ..... reported were cell phone alarm, radio news hour time, or a.

  20. Demonstration and Optimization of BNFL's Pulsed Jet Mixing and RFD Sampling Systems Using NCAW Simulant

    International Nuclear Information System (INIS)

    Bontha, J.R.; Golcar, G.R.; Hannigan, N.

    2000-01-01

    The BNFL Inc. flowsheet for the pretreatment and vitrification of the Hanford High Level Tank waste includes the use of several hundred Reverse Flow Diverters (RFDs) for sampling and transferring the radioactive slurries and Pulsed Jet mixers to homogenize or suspend the tank contents. The Pulsed Jet mixing and the RFD sampling devices represent very simple and efficient methods to mix and sample slurries, respectively, using compressed air to achieve the desired operation. The equipment has no moving parts, which makes them very suitable for mixing and sampling highly radioactive wastes. However, the effectiveness of the mixing and sampling systems are yet to be demonstrated when dealing with Hanford slurries, which exhibit a wide range of physical and theological properties. This report describes the results of the testing of BNFL's Pulsed Jet mixing and RFD sampling systems in a 13-ft ID and 15-ft height dish-bottomed tank at Battelle's 336 building high-bay facility using AZ-101/102 simulants containing up to 36-wt% insoluble solids. The specific objectives of the work were to: Demonstrate the effectiveness of the Pulsed Jet mixing system to thoroughly homogenize Hanford-type slurries over a range of solids loading; Minimize/optimize air usage by changing sequencing of the Pulsed Jet mixers or by altering cycle times; and Demonstrate that the RFD sampler can obtain representative samples of the slurry up to the maximum RPP-WTP baseline concentration of 25-wt%

  1. On the optimal sampling of bandpass measurement signals through data acquisition systems

    International Nuclear Information System (INIS)

    Angrisani, L; Vadursi, M

    2008-01-01

    Data acquisition systems (DAS) play a fundamental role in a lot of modern measurement solutions. One of the parameters characterizing a DAS is its maximum sample rate, which imposes constraints on the signals that can be alias-free digitized. Bandpass sampling theory singles out separated ranges of admissible sample rates, which can be significantly lower than carrier frequency. But, how to choose the most convenient sample rate according to the purpose at hand? The paper proposes a method for the automatic selection of the optimal sample rate in measurement applications involving bandpass signals; the effects of sample clock instability and limited resolution are also taken into account. The method allows the user to choose the location of spectral replicas of the sampled signal in terms of normalized frequency, and the minimum guard band between replicas, thus introducing a feature that no DAS currently available on the market seems to offer. A number of experimental tests on bandpass digitally modulated signals are carried out to assess the concurrence of the obtained central frequency with the expected one

  2. Development of a Cloud-Point Extraction Method for Cobalt Determination in Natural Water Samples

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Jamali

    2013-01-01

    Full Text Available A new, simple, and versatile cloud-point extraction (CPE methodology has been developed for the separation and preconcentration of cobalt. The cobalt ions in the initial aqueous solution were complexed with 4-Benzylpiperidinedithiocarbamate, and Triton X-114 was added as surfactant. Dilution of the surfactant-rich phase with acidified ethanol was performed after phase separation, and the cobalt content was measured by flame atomic absorption spectrometry. The main factors affecting CPE procedure, such as pH, concentration of ligand, amount of Triton X-114, equilibrium temperature, and incubation time were investigated and optimized. Under the optimal conditions, the limit of detection (LOD for cobalt was 0.5 μg L-1, with sensitivity enhancement factor (EF of 67. Calibration curve was linear in the range of 2–150 μg L-1, and relative standard deviation was 3.2% (c=100 μg L-1; n=10. The proposed method was applied to the determination of trace cobalt in real water samples with satisfactory analytical results.

  3. Determination of volatile organic hydrocarbons in water samples by solid-phase dynamic extraction.

    Science.gov (United States)

    Jochmann, Maik A; Yuan, Xue; Schmidt, Torsten C

    2007-03-01

    In the present study a headspace solid-phase dynamic extraction method coupled to gas chromatography-mass spectrometry (HS-SPDE-GC/MS) for the trace determination of volatile halogenated hydrocarbons and benzene from groundwater samples was developed and evaluated. As target compounds, benzene as well as 11 chlorinated and brominated hydrocarbons (vinyl chloride, dichloromethane, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, carbon tetrachloride, chloroform, trichloroethylene, tetrachloroethylene, bromoform) of environmental and toxicological concern were included in this study. The analytes were extracted using a SPDE needle device, coated with a poly(dimethylsiloxane) with 10% embedded activated carbon phase (50-microm film thickness and 56-mm film length) and were analyzed by GC/MS in full-scan mode. Parameters that affect the extraction yield such as extraction and desorption temperature, salting-out, extraction and desorption flow rate, extraction volume and desorption volume, the number of extraction cycles, and the pre-desorption time have been evaluated and optimized. The linearity of the HS-SPDE-GC/MS method was established over several orders of magnitude. Method detection limits (MDLs) for the compounds investigated ranged between 12 ng/L for cis-dichloroethylene and trans-dichloroethylene and 870 ng/L for vinyl chloride. The method was thoroughly validated, and the precision at two concentration levels (0.1 mg/L and a concentration 5 times above the MDL) was between 3.1 and 16% for the analytes investigated. SPDE provides high sensitivity, short sample preparation and extraction times and a high sample throughput because of full automation. Finally, the applicability to real environmental samples is shown exemplarily for various groundwater samples from a former waste-oil recycling facility. Groundwater from the site showed a complex contamination with chlorinated volatile organic compounds and aromatic hydrocarbons.

  4. Determination of volatile organic hydrocarbons in water samples by solid-phase dynamic extraction

    Energy Technology Data Exchange (ETDEWEB)

    Jochmann, Maik A.; Schmidt, Torsten C. [Eberhard-Karls-Universitaet Tuebingen, Center for Applied Geoscience (ZAG), Tuebingen (Germany); Chair of Instrumental Analysis, University Duisburg-Essen, Duisburg (Germany); Yuan, Xue [Eberhard-Karls-Universitaet Tuebingen, Center for Applied Geoscience (ZAG), Tuebingen (Germany)

    2007-03-15

    In the present study a headspace solid-phase dynamic extraction method coupled to gas chromatography-mass spectrometry (HS-SPDE-GC/MS) for the trace determination of volatile halogenated hydrocarbons and benzene from groundwater samples was developed and evaluated. As target compounds, benzene as well as 11 chlorinated and brominated hydrocarbons (vinyl chloride, dichloromethane, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, carbon tetrachloride, chloroform, trichloroethylene, tetrachloroethylene, bromoform) of environmental and toxicological concern were included in this study. The analytes were extracted using a SPDE needle device, coated with a poly(dimethylsiloxane) with 10% embedded activated carbon phase (50-{mu}m film thickness and 56-mm film length) and were analyzed by GC/MS in full-scan mode. Parameters that affect the extraction yield such as extraction and desorption temperature, salting-out, extraction and desorption flow rate, extraction volume and desorption volume, the number of extraction cycles, and the pre-desorption time have been evaluated and optimized. The linearity of the HS-SPDE-GC/MS method was established over several orders of magnitude. Method detection limits (MDLs) for the compounds investigated ranged between 12 ng/L for cis-dichloroethylene and trans-dichloroethylene and 870 ng/L for vinyl chloride. The method was thoroughly validated, and the precision at two concentration levels (0.1 mg/L and a concentration 5 times above the MDL) was between 3.1 and 16% for the analytes investigated. SPDE provides high sensitivity, short sample preparation and extraction times and a high sample throughput because of full automation. Finally, the applicability to real environmental samples is shown exemplarily for various groundwater samples from a former waste-oil recycling facility. Groundwater from the site showed a complex contamination with chlorinated volatile organic compounds and aromatic hydrocarbons. (orig.)

  5. Cloud point extraction and flame atomic absorption spectrometric determination of cadmium and nickel in drinking and wastewater samples.

    Science.gov (United States)

    Naeemullah; Kazi, Tasneem G; Shah, Faheem; Afridi, Hassan I; Baig, Jameel Ahmed; Soomro, Abdul Sattar

    2013-01-01

    A simple method for the preconcentration of cadmium (Cd) and nickel (Ni) in drinking and wastewater samples was developed. Cloud point extraction has been used for the preconcentration of both metals, after formation of complexes with 8-hydroxyquinoline (8-HQ) and extraction with the surfactant octylphenoxypolyethoxyethanol (Triton X-114). Dilution of the surfactant-rich phase with acidified ethanol was performed after phase separation, and the Cd and Ni contents were measured by flame atomic absorption spectrometry. The experimental variables, such as pH, amounts of reagents (8-HQ and Triton X-114), temperature, incubation time, and sample volume, were optimized. After optimization of the complexation and extraction conditions, enhancement factors of 80 and 61, with LOD values of 0.22 and 0.52 microg/L, were obtained for Cd and Ni, respectively. The proposed method was applied satisfactorily for the determination of both elements in drinking and wastewater samples.

  6. Optimizing the radioimmunologic determination methods for cortisol and calcitonin

    International Nuclear Information System (INIS)

    Stalla, G.

    1981-01-01

    In order to build up a specific 125-iodine cortisol radioimmunoassay (RIA) pure cortisol-3(0-carbodxymethyl) oxim was synthesized for teh production of antigens and tracers. The cortisol was coupled with tyrosin methylester and then labelled with 125-iodine. For the antigen production the cortisol derivate was coupled with the same method to thyreoglobulin. The major part of the antisera, which were obtained like this, presented high titres. Apart from a high specificity for cortisol a high affinity was found in the acid pH-area and quantified with a particularly developed computer program. An extractive step in the cortisol RIA could be prevented by efforts. The assay was carried out with an optimized double antibody principle: The reaction time between the first and the second antiserum was considerably accelerated by the administration of polyaethylenglycol. The assay can be carried out automatically by applying a modular analysis system, which operates fast and provides a large capacity. The required quality and accuracy controls were done. The comparison of this assay with other cortisol-RIA showed good correlation. The RIA for human clacitonin was improved. For separating bound and freely mobile hormones the optimized double-antibody technique was applied. The antiserum was examined with respect to its affinity to calcitonin. For the 'zero serum' production the Florisil extraction method was used. The criteria of the quality and accuracy controls were complied. Significantly increased calcitonin concentrations were found in a patient group with medullar thyroid carcinoma and in two patients with an additional phaechromocytoma. (orig./MG) [de

  7. Optimization of a sample processing protocol for recovery of Bacillus anthracis spores from soil

    Science.gov (United States)

    Silvestri, Erin E.; Feldhake, David; Griffin, Dale; Lisle, John T.; Nichols, Tonya L.; Shah, Sanjiv; Pemberton, A; Schaefer III, Frank W

    2016-01-01

    Following a release of Bacillus anthracis spores into the environment, there is a potential for lasting environmental contamination in soils. There is a need for detection protocols for B. anthracis in environmental matrices. However, identification of B. anthracis within a soil is a difficult task. Processing soil samples helps to remove debris, chemical components, and biological impurities that can interfere with microbiological detection. This study aimed to optimize a previously used indirect processing protocol, which included a series of washing and centrifugation steps. Optimization of the protocol included: identifying an ideal extraction diluent, variation in the number of wash steps, variation in the initial centrifugation speed, sonication and shaking mechanisms. The optimized protocol was demonstrated at two laboratories in order to evaluate the recovery of spores from loamy and sandy soils. The new protocol demonstrated an improved limit of detection for loamy and sandy soils over the non-optimized protocol with an approximate matrix limit of detection at 14 spores/g of soil. There were no significant differences overall between the two laboratories for either soil type, suggesting that the processing protocol will be robust enough to use at multiple laboratories while achieving comparable recoveries.

  8. Determination of cadmium in real water samples by flame atomic absorption spectrometry after cloud point extraction

    International Nuclear Information System (INIS)

    Naeemullah, A.; Kazi, T.G.

    2011-01-01

    Water pollution is a global threat and it is the leading world wide cause of death and diseases. The awareness of the potential danger posed by heavy metals to the ecosystems and in particular to human health has grown tremendously in the past decades. Separation and preconcentration procedures are considered of great importance in analytical and environmental chemistry. Cloud point is one of the most reliable and sophisticated separation methods for determination of traces quantities of heavy metals. Cloud point methodology was successfully employed for preconcentration of trace quantities of cadmium prior to their determination by flame atomic absorption spectrometry (FAAS). The metals react with 8-hydroxquinoline in a surfactant Triton X-114 medium. The following parameters such as pH, concentration of the reagent and Triton X-114, equilibrating temperature and centrifuging time were evaluated and optimized to enhance the sensitivity and extraction efficiency of the proposed method. Dilution of the surfactant-rich phase with acidified ethanol was performed after phase separation and the cadmium content was measured by FAAS. The validation of the procedure was carried out by spiking addition methods. The method was applied for determination of Cd in water samples of different ecosystems (lake and river). (author)

  9. Studies on voltammetric determination of cadmium in samples containing native and digested proteins

    Energy Technology Data Exchange (ETDEWEB)

    Drozd, Marcin; Pietrzak, Mariusz, E-mail: mariusz@ch.pw.edu.pl; Malinowska, Elżbieta

    2014-03-01

    Highlights: • Proteins exhibit diverse impact on the DPASV cadmium signals. • Proteins subjected to HNO{sub 3} introduce less interference, than the native ones. • Optimal amount of SDS depends on the kind of protein. • Presence of thiolated coating agents of QDs do not influence the analysis. - Abstract: This work focuses on determination of cadmium ions using anodic stripping voltammetry (ASV) on thin film mercury electrode in conditions corresponding to those obtained after digestion of cadmium-based quantum dots and their conjugates. It presents the impact of selected proteins, including potential receptors and surface blocking agents on the voltammetric determination of cadmium. Experiments regarding elimination of interferences related to proteins presence using sodium dodecyl sulfate (SDS) are also shown. Effect of SDS on selected analytical parameters and simplicity of analyses carried out was investigated in the framework of current studies. The significant differences of influence among tested proteins on ASV cadmium determination, as well as the variability in SDS effectiveness as the antifouling agent were observed and explained. This work is especially important for those, who design new bioassays and biosensors with a use of quantum dots as electrochemical labels, as it shows what problems may arise from presence of native and digested proteins in tested samples.

  10. Foam generation and sample composition optimization for the FOAM-C experiment of the ISS

    International Nuclear Information System (INIS)

    Carpy, R; Picker, G; Amann, B; Ranebo, H; Vincent-Bonnieu, S; Minster, O; Winter, J; Dettmann, J; Castiglione, L; Höhler, R; Langevin, D

    2011-01-01

    End of 2009 and early 2010 a sealed cell, for foam generation and observation, has been designed and manufactured at Astrium Friedrichshafen facilities. With the use of this cell, different sample compositions of 'wet foams' have been optimized for mixtures of chemicals such as water, dodecanol, pluronic, aethoxisclerol, glycerol, CTAB, SDS, as well as glass beads. This development is performed in the frame of the breadboarding development activities of the Experiment Container FOAM-C for operation in the ISS Fluid Science Laboratory (ISS). The sample cell supports multiple observation methods such as: Diffusing-Wave and Diffuse Transmission Spectrometry, Time Resolved Correlation Spectroscopy and microscope observation, all of these methods are applied in the cell with a relatively small experiment volume 3 . These units, will be on orbit replaceable sets, that will allow multiple sample compositions processing (in the range of >40).

  11. Racing Sampling Based Microimmune Optimization Approach Solving Constrained Expected Value Programming

    Directory of Open Access Journals (Sweden)

    Kai Yang

    2016-01-01

    Full Text Available This work investigates a bioinspired microimmune optimization algorithm to solve a general kind of single-objective nonlinear constrained expected value programming without any prior distribution. In the study of algorithm, two lower bound sample estimates of random variables are theoretically developed to estimate the empirical values of individuals. Two adaptive racing sampling schemes are designed to identify those competitive individuals in a given population, by which high-quality individuals can obtain large sampling size. An immune evolutionary mechanism, along with a local search approach, is constructed to evolve the current population. The comparative experiments have showed that the proposed algorithm can effectively solve higher-dimensional benchmark problems and is of potential for further applications.

  12. Rats track odour trails accurately using a multi-layered strategy with near-optimal sampling.

    Science.gov (United States)

    Khan, Adil Ghani; Sarangi, Manaswini; Bhalla, Upinder Singh

    2012-02-28

    Tracking odour trails is a crucial behaviour for many animals, often leading to food, mates or away from danger. It is an excellent example of active sampling, where the animal itself controls how to sense the environment. Here we show that rats can track odour trails accurately with near-optimal sampling. We trained rats to follow odour trails drawn on paper spooled through a treadmill. By recording local field potentials (LFPs) from the olfactory bulb, and sniffing rates, we find that sniffing but not LFPs differ between tracking and non-tracking conditions. Rats can track odours within ~1 cm, and this accuracy is degraded when one nostril is closed. Moreover, they show path prediction on encountering a fork, wide 'casting' sweeps on encountering a gap and detection of reappearance of the trail in 1-2 sniffs. We suggest that rats use a multi-layered strategy, and achieve efficient sampling and high accuracy in this complex task.

  13. Anodic electrode position of cyanometallates as sample preparation for the determination of transition metals from water samples using X-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Wundt, K.; Duschner, H.; Starke, K.

    1978-01-01

    The anodic separation of cyanometallates of propanol -2/Water mixtures at high electrical field strengths was developed as new technique for sample preparation. The optimization of the parameters of the system (high voltage applied, current density, separation time and composition of the solution) resulted in quantitative precipitation of the metallates of Fe, Co, Ni, Cu, Zn, Cd and Ag in homogeneous, thin and strong-adhering layer with mass densities of between 1 nmol cm -2 and 1 μmol cm -2 on high-purity aluminium foils. Metals not forming anionic complexes remain in solution with simualtaneous quantitative multielement separation. The described technique is part of a method to determine heavy metal traces in water samples. It comprises the nonspecific sorption on cation exchangers, the elution of the transition metals as cyanometallates, their electrode position on aluminium foil and the determination by X-ray fluorescence analysis. Model experiments illustrate the possible applications of the method. (orig.) [de

  14. An Optimized Method for Quantification of Pathogenic Leptospira in Environmental Water Samples.

    Science.gov (United States)

    Riediger, Irina N; Hoffmaster, Alex R; Casanovas-Massana, Arnau; Biondo, Alexander W; Ko, Albert I; Stoddard, Robyn A

    2016-01-01

    Leptospirosis is a zoonotic disease usually acquired by contact with water contaminated with urine of infected animals. However, few molecular methods have been used to monitor or quantify pathogenic Leptospira in environmental water samples. Here we optimized a DNA extraction method for the quantification of leptospires using a previously described Taqman-based qPCR method targeting lipL32, a gene unique to and highly conserved in pathogenic Leptospira. QIAamp DNA mini, MO BIO PowerWater DNA and PowerSoil DNA Isolation kits were evaluated to extract DNA from sewage, pond, river and ultrapure water samples spiked with leptospires. Performance of each kit varied with sample type. Sample processing methods were further evaluated and optimized using the PowerSoil DNA kit due to its performance on turbid water samples and reproducibility. Centrifugation speeds, water volumes and use of Escherichia coli as a carrier were compared to improve DNA recovery. All matrices showed a strong linearity in a range of concentrations from 106 to 10° leptospires/mL and lower limits of detection ranging from Leptospira in environmental waters (river, pond and sewage) which consists of the concentration of 40 mL samples by centrifugation at 15,000×g for 20 minutes at 4°C, followed by DNA extraction with the PowerSoil DNA Isolation kit. Although the method described herein needs to be validated in environmental studies, it potentially provides the opportunity for effective, timely and sensitive assessment of environmental leptospiral burden.

  15. Determination of the optimal number of components in independent components analysis.

    Science.gov (United States)

    Kassouf, Amine; Jouan-Rimbaud Bouveresse, Delphine; Rutledge, Douglas N

    2018-03-01

    Independent components analysis (ICA) may be considered as one of the most established blind source separation techniques for the treatment of complex data sets in analytical chemistry. Like other similar methods, the determination of the optimal number of latent variables, in this case, independent components (ICs), is a crucial step before any modeling. Therefore, validation methods are required in order to decide about the optimal number of ICs to be used in the computation of the final model. In this paper, three new validation methods are formally presented. The first one, called Random_ICA, is a generalization of the ICA_by_blocks method. Its specificity resides in the random way of splitting the initial data matrix into two blocks, and then repeating this procedure several times, giving a broader perspective for the selection of the optimal number of ICs. The second method, called KMO_ICA_Residuals is based on the computation of the Kaiser-Meyer-Olkin (KMO) index of the transposed residual matrices obtained after progressive extraction of ICs. The third method, called ICA_corr_y, helps to select the optimal number of ICs by computing the correlations between calculated proportions and known physico-chemical information about samples, generally concentrations, or between a source signal known to be present in the mixture and the signals extracted by ICA. These three methods were tested using varied simulated and experimental data sets and compared, when necessary, to ICA_by_blocks. Results were relevant and in line with expected ones, proving the reliability of the three proposed methods. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Efficient approach for reliability-based optimization based on weighted importance sampling approach

    International Nuclear Information System (INIS)

    Yuan, Xiukai; Lu, Zhenzhou

    2014-01-01

    An efficient methodology is presented to perform the reliability-based optimization (RBO). It is based on an efficient weighted approach for constructing an approximation of the failure probability as an explicit function of the design variables which is referred to as the ‘failure probability function (FPF)’. It expresses the FPF as a weighted sum of sample values obtained in the simulation-based reliability analysis. The required computational effort for decoupling in each iteration is just single reliability analysis. After the approximation of the FPF is established, the target RBO problem can be decoupled into a deterministic one. Meanwhile, the proposed weighted approach is combined with a decoupling approach and a sequential approximate optimization framework. Engineering examples are given to demonstrate the efficiency and accuracy of the presented methodology

  17. Optimal cross-sectional sampling for river modelling with bridges: An information theory-based method

    Energy Technology Data Exchange (ETDEWEB)

    Ridolfi, E.; Napolitano, F., E-mail: francesco.napolitano@uniroma1.it [Sapienza Università di Roma, Dipartimento di Ingegneria Civile, Edile e Ambientale (Italy); Alfonso, L. [Hydroinformatics Chair Group, UNESCO-IHE, Delft (Netherlands); Di Baldassarre, G. [Department of Earth Sciences, Program for Air, Water and Landscape Sciences, Uppsala University (Sweden)

    2016-06-08

    The description of river topography has a crucial role in accurate one-dimensional (1D) hydraulic modelling. Specifically, cross-sectional data define the riverbed elevation, the flood-prone area, and thus, the hydraulic behavior of the river. Here, the problem of the optimal cross-sectional spacing is solved through an information theory-based concept. The optimal subset of locations is the one with the maximum information content and the minimum amount of redundancy. The original contribution is the introduction of a methodology to sample river cross sections in the presence of bridges. The approach is tested on the Grosseto River (IT) and is compared to existing guidelines. The results show that the information theory-based approach can support traditional methods to estimate rivers’ cross-sectional spacing.

  18. Optimal cross-sectional sampling for river modelling with bridges: An information theory-based method

    International Nuclear Information System (INIS)

    Ridolfi, E.; Napolitano, F.; Alfonso, L.; Di Baldassarre, G.

    2016-01-01

    The description of river topography has a crucial role in accurate one-dimensional (1D) hydraulic modelling. Specifically, cross-sectional data define the riverbed elevation, the flood-prone area, and thus, the hydraulic behavior of the river. Here, the problem of the optimal cross-sectional spacing is solved through an information theory-based concept. The optimal subset of locations is the one with the maximum information content and the minimum amount of redundancy. The original contribution is the introduction of a methodology to sample river cross sections in the presence of bridges. The approach is tested on the Grosseto River (IT) and is compared to existing guidelines. The results show that the information theory-based approach can support traditional methods to estimate rivers’ cross-sectional spacing.

  19. A Demonstration of Optimal Apodization Determination for Proper Lateral Modulation

    Science.gov (United States)

    Sumi, Chikayoshi; Komiya, Yuichi; Uga, Shinya

    2009-07-01

    We have realized effective ultrasound (US) beamformings by the steering of plural beams and apodizations for B-mode imaging with a high lateral resolution and accurate measurement of tissue or blood displacement vector and/or strain tensor using the multidimensional cross-spectrum phase gradient method (MCSPGM), or multidimensional autocorrelation or Doppler methods (MAM and MDM) using multidimensional analytic signals. For instance, the coherent superposition of the steered beams performed in the lateral cosine modulation method (LCM) has a higher potential for realizing a more accurate measurement of a displacement vector than the synthesis of the displacement vector using the accurately measured axial displacements obtained by the multidimensional synthetic aperture method (MDSAM), multidirectional transmission method (MTM) or the use of plural US transducers. Originally, the apodization function to be used for realizing a designed point spread function (PSF) was obtained by the Fraunhofer approximation (FA). However, to obtain the best approximated, designed PSF in the least-squares sense, we proposed a linear optimization (LO) method. Furthermore, on the basis of the knowledge about the losts of US energy during the propagation, we have recently developed a nonlinear optimization (NLO) method, in which the feet of the main lobes in apodization function are properly truncated. Thus, NLO also allows the decrease in the number of channels or the confinement of the effective aperture. In this study, to gain insight into the ideal shape of the PSF, the accuracies of the two-dimensional (2D) displacement vector measurements were compared for typical PSFs with distinct lateral envelope shapes, particularly, in terms of full width at half maximum (FWHM) and the length of the feet, i.e., the Gaussian function, Hanning window and parabolic function. It was confirmed that a PSF having a wide FWHM and short feet was ideal. Such a PSF yielded an echo with a high signal

  20. Determining optimal pinger spacing for harbour porpoise bycatch mitigation

    DEFF Research Database (Denmark)

    Larsen, Finn; Krog, Carsten; Eigaard, Ole Ritzau

    2013-01-01

    A trial was conducted in the Danish North Sea hake gillnet fishery in July to September 2006 to determine whether the spacing of the Aquatec AQUAmark100 pinger could be increased without reducing the effectiveness of the pinger in mitigating harbour porpoise bycatch. The trial was designed as a c...

  1. Brachytherapy dose-volume histogram computations using optimized stratified sampling methods

    International Nuclear Information System (INIS)

    Karouzakis, K.; Lahanas, M.; Milickovic, N.; Giannouli, S.; Baltas, D.; Zamboglou, N.

    2002-01-01

    A stratified sampling method for the efficient repeated computation of dose-volume histograms (DVHs) in brachytherapy is presented as used for anatomy based brachytherapy optimization methods. The aim of the method is to reduce the number of sampling points required for the calculation of DVHs for the body and the PTV. From the DVHs are derived the quantities such as Conformity Index COIN and COIN integrals. This is achieved by using partial uniform distributed sampling points with a density in each region obtained from a survey of the gradients or the variance of the dose distribution in these regions. The shape of the sampling regions is adapted to the patient anatomy and the shape and size of the implant. For the application of this method a single preprocessing step is necessary which requires only a few seconds. Ten clinical implants were used to study the appropriate number of sampling points, given a required accuracy for quantities such as cumulative DVHs, COIN indices and COIN integrals. We found that DVHs of very large tissue volumes surrounding the PTV, and also COIN distributions, can be obtained using a factor of 5-10 times smaller the number of sampling points in comparison with uniform distributed points

  2. A New Technique for Quantitative Determination of Dexamethasone in Pharmaceutical and Biological Samples Using Kinetic Spectrophotometric Method

    Directory of Open Access Journals (Sweden)

    Ali Mohammad Akhoundi-Khalafi

    2015-01-01

    Full Text Available Dexamethasone is a type of steroidal medications that is prescribed in many cases. In this study, a new reaction system using kinetic spectrophotometric method for quantitative determination of dexamethasone is proposed. The method is based on the catalytic effect of dexamethasone on the oxidation of Orange G by bromate in acidic media. The change in absorbance as a criterion of the oxidation reaction progress was followed spectrophotometrically. To obtain the maximum sensitivity, the effective reaction variables were optimized. Under optimized experimental conditions, calibration graph was linear over the range 0.2–54.0 mg L−1. The calculated detection limit (3sb/m was 0.14 mg L−1 for six replicate determinations of blank signal. The interfering effect of various species was also investigated. The present method was successfully applied for the determination of dexamethasone in pharmaceutical and biological samples satisfactorily.

  3. Optimal sampling in damage detection of flexural beams by continuous wavelet transform

    International Nuclear Information System (INIS)

    Basu, B; Broderick, B M; Montanari, L; Spagnoli, A

    2015-01-01

    Modern measurement techniques are improving in capability to capture spatial displacement fields occurring in deformed structures with high precision and in a quasi-continuous manner. This in turn has made the use of vibration-based damage identification methods more effective and reliable for real applications. However, practical measurement and data processing issues still present barriers to the application of these methods in identifying several types of structural damage. This paper deals with spatial Continuous Wavelet Transform (CWT) damage identification methods in beam structures with the aim of addressing the following key questions: (i) can the cost of damage detection be reduced by down-sampling? (ii) what is the minimum number of sampling intervals required for optimal damage detection ? The first three free vibration modes of a cantilever and a simple supported beam with an edge open crack are numerically simulated. A thorough parametric study is carried out by taking into account the key parameters governing the problem, including level of noise, crack depth and location, mechanical and geometrical parameters of the beam. The results are employed to assess the optimal number of sampling intervals for effective damage detection. (paper)

  4. Determining the optimal monetary policy instrument for Nigeria

    OpenAIRE

    Udom, Solomon I.; Yaaba, Baba N.

    2015-01-01

    It is considered inapt for central banks to adjust reserve money (quantity of money) and interest rate (price of money) at the same time. Thus, necessitates the need for a choice instrument. Enough evidence abounds in microeconomic theory on the undesirability of manipulating both price and quantity simultaneously in a free market structure. The market, in line with the consensus among economists, either controls the price and allows quantity to be determined by market forces, or influence qu...

  5. Determination of oligomers in virgin and recycled polyethylene terephthalate (PET) samples by UPLC-MS-QTOF.

    Science.gov (United States)

    Ubeda, Sara; Aznar, Margarita; Nerín, Cristina

    2018-03-01

    An oligomer is a molecule that consists of a few monomer units. It can be formed during polymer manufacturing and also due to polymer degradation processes or even during use conditions. Since oligomers are not included in chemical databases, their identification is a complex process. In this work, the oligomers present in 20 different PET pellet samples have been determined. Two different sample treatment procedures, solvent extraction and total dissolution, were applied in order to select the most efficient one. The analyses were carried out by UPLC-MS-QTOF. The use of high resolution mass spectrometry allowed the structural elucidation of these compounds and their correct identification. The main oligomers identified were cyclic as well as lineal from the first, second, and third series. All of them were composed of terephthalic acid (TPA), diethylene glycol (DEG), and ethylene glycol (EG). Quantitative values were very different in both procedures. In total dissolution of PET samples, the concentration of oligomers was always, at least, 10 times higher than in solvent extraction; some of the compounds were only detected when total dissolution was used. Results showed that the oligomers with the highest concentration values were dimers and trimers, cyclic, as well as lineal, from the first and second series. The oligomer with the maximum concentration value was TPA 2 -EG-DEG that was found in all the samples in a concentration range from 2493 to 19,290 ng/g PET. No differences between virgin and recycled PET were found. Migration experiments were performed in two PET bottles, and results showed the transference of most of these oligomers to a fat food simulant (ethanol 95%). Graphical abstract Graphical abstract of the two procedures developd and optimized for identifying oligomers in PET pellets and in migration form PET bottles.

  6. Employing natural reagents from turmeric and lime for acetic acid determination in vinegar sample.

    Science.gov (United States)

    Supharoek, Sam-Ang; Ponhong, Kraingkrai; Siriangkhawut, Watsaka; Grudpan, Kate

    2018-04-01

    A simple, rapid and environmentally friendly sequential injection analysis system employing natural extract reagents was developed for the determination of acetic acid following an acid-base reaction in the presence of an indicator. Powdered lime and turmeric were utilized as the natural base and indicator, respectively. Mixing lime and turmeric produced an orange to reddish-brown color solution which absorbed the maximum wavelength at 455 nm, with absorbance decreasing with increasing acetic acid concentration. Influential parameters including lime and turmeric concentrations, reagent and sample aspirated volumes, mixing coil length and dispensing flow rate were investigated and optimized. A standard calibration graph was plotted for 0-5.0 mmol/L acetic acid with r 2  = 0.9925. Relative standard deviations (RSD) at 2.0 and 4.0 mmol/L acetic acid were less than 3% (n = 7), with limit of detection (LOD) and limit of quantification (LOQ) at 0.12 and 0.24 mmol/L, respectively. The method was successfully applied to assay acetic acid concentration in cooking vinegar samples. Results achieved were not significantly different from those obtained following a batchwise standard AOAC titration method. Copyright © 2017. Published by Elsevier B.V.

  7. Employing natural reagents from turmeric and lime for acetic acid determination in vinegar sample

    Directory of Open Access Journals (Sweden)

    Sam-ang Supharoek

    2018-04-01

    Full Text Available A simple, rapid and environmentally friendly sequential injection analysis system employing natural extract reagents was developed for the determination of acetic acid following an acid–base reaction in the presence of an indicator. Powdered lime and turmeric were utilized as the natural base and indicator, respectively. Mixing lime and turmeric produced an orange to reddish-brown color solution which absorbed the maximum wavelength at 455 nm, with absorbance decreasing with increasing acetic acid concentration. Influential parameters including lime and turmeric concentrations, reagent and sample aspirated volumes, mixing coil length and dispensing flow rate were investigated and optimized. A standard calibration graph was plotted for 0–5.0 mmol/L acetic acid with r2 = 0.9925. Relative standard deviations (RSD at 2.0 and 4.0 mmol/L acetic acid were less than 3% (n = 7, with limit of detection (LOD and limit of quantification (LOQ at 0.12 and 0.24 mmol/L, respectively. The method was successfully applied to assay acetic acid concentration in cooking vinegar samples. Results achieved were not significantly different from those obtained following a batchwise standard AOAC titration method. Keywords: Acetic acid assay, Natural reagent, Turmeric, Lime, Sequential injection analysis

  8. Sulfur determination in concrete samples using laser-induced breakdown spectroscopy and limestone standards

    Science.gov (United States)

    Hrdlička, Aleš; Hegrová, Jitka; Novotný, Karel; Kanický, Viktor; Prochazka, David; Novotný, Jan; Modlitbová, Pavlína; Sládková, Lucia; Pořízka, Pavel; Kaiser, Jozef

    2018-04-01

    A LIBS equipment operating at 532 nm was optimized and used for sulfur determination in concrete samples. The influence of He atmosphere in a gas-tight chamber (1000-200 mbar) on S I 921.29 nm line sensitivity, signal-to-background and signal-to-noise ratio was studied at gate delays 100-2000 ns. Wide range of gate delays from 500 to about 1000 ns and pressures from several hundreds of mbar to the atmospheric pressure can be used for the desired detection of sulfur. The LIBS quantification was done using a simple calibration method. A synthetic limestone enriched by defined amounts of sodium sulfate was newly employed for direct quantification of S in concrete. This powder material was pressed into pellets and ablated with the LIBS system. The average content of sulfur as SO3 in the samples was 0.41-0.70 wt% by LIBS and 0.43-0.61 wt% by a reference standard procedure employing gravimetry and Inductively Coupled Plasma Triple Quad Mass Spectrometry (ICP-QQQMS). The uncertainty of the yielded LIBS results covers also the dispersion of the points in the calibration line and ranges from 16 to 28% at the probability level of 95%. The uncertainty of the ICP-QQQMS results was almost 10%. No correction on different signal response on the limestone and on the concrete was necessary.

  9. Determination of some metal ions in various meat and baby food samples by atomic spectrometry.

    Science.gov (United States)

    Daşbaşı, Teslima; Saçmacı, Şerife; Ülgen, Ahmet; Kartal, Şenol

    2016-04-15

    In this paper, we report a simple and rapid solid phase extraction system for the separation/preconcentration and determination of Cd(II), Co(II), Cu(II), Fe(III), Cr(III), Pb(II), and Zn(II) ions by flame atomic absorption spectrometry (FAAS). This method is based upon the retention of metal ions on a column packed with poly[N-(3-methyl-1H-indole-1-yl)]-2-methacrylamide-co-2-acrylamido-2-methyl-1-propane sulphonic acid-co divinylbenzene] (MMAD) resin as a solid-phase extraction (SPE) sorbent at pH 8. At the optimized conditions, the limits of detection (3 s/b) between 0.12 and 1.6 μg L(-1), preconcentration factor of 100, and the relative standard deviation of ⩽1.8% were achieved (n=10). The accuracy of the method was verified by analyzing certified reference materials (CRMs) and performing recovery experiments. The developed method was successfully applied to the various natural water, meat products and baby food samples. The recoveries of analyte ions were found in added real samples and CRMs from 95% to 102%. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Optimization of sampling pattern and the design of Fourier ptychographic illuminator.

    Science.gov (United States)

    Guo, Kaikai; Dong, Siyuan; Nanda, Pariksheet; Zheng, Guoan

    2015-03-09

    Fourier ptychography (FP) is a recently developed imaging approach that facilitates high-resolution imaging beyond the cutoff frequency of the employed optics. In the original FP approach, a periodic LED array is used for sample illumination, and therefore, the scanning pattern is a uniform grid in the Fourier space. Such a uniform sampling scheme leads to 3 major problems for FP, namely: 1) it requires a large number of raw images, 2) it introduces the raster grid artefacts in the reconstruction process, and 3) it requires a high-dynamic-range detector. Here, we investigate scanning sequences and sampling patterns to optimize the FP approach. For most biological samples, signal energy is concentrated at low-frequency region, and as such, we can perform non-uniform Fourier sampling in FP by considering the signal structure. In contrast, conventional ptychography perform uniform sampling over the entire real space. To implement the non-uniform Fourier sampling scheme in FP, we have designed and built an illuminator using LEDs mounted on a 3D-printed plastic case. The advantages of this illuminator are threefold in that: 1) it reduces the number of image acquisitions by at least 50% (68 raw images versus 137 in the original FP setup), 2) it departs from the translational symmetry of sampling to solve the raster grid artifact problem, and 3) it reduces the dynamic range of the captured images 6 fold. The results reported in this paper significantly shortened acquisition time and improved quality of FP reconstructions. It may provide new insights for developing Fourier ptychographic imaging platforms and find important applications in digital pathology.

  11. Optimization of the solvent-based dissolution method to sample volatile organic compound vapors for compound-specific isotope analysis.

    Science.gov (United States)

    Bouchard, Daniel; Wanner, Philipp; Luo, Hong; McLoughlin, Patrick W; Henderson, James K; Pirkle, Robert J; Hunkeler, Daniel

    2017-10-20

    The methodology of the solvent-based dissolution method used to sample gas phase volatile organic compounds (VOC) for compound-specific isotope analysis (CSIA) was optimized to lower the method detection limits for TCE and benzene. The sampling methodology previously evaluated by [1] consists in pulling the air through a solvent to dissolve and accumulate the gaseous VOC. After the sampling process, the solvent can then be treated similarly as groundwater samples to perform routine CSIA by diluting an aliquot of the solvent into water to reach the required concentration of the targeted contaminant. Among solvents tested, tetraethylene glycol dimethyl ether (TGDE) showed the best aptitude for the method. TGDE has a great affinity with TCE and benzene, hence efficiently dissolving the compounds during their transition through the solvent. The method detection limit for TCE (5±1μg/m 3 ) and benzene (1.7±0.5μg/m 3 ) is lower when using TGDE compared to methanol, which was previously used (385μg/m 3 for TCE and 130μg/m 3 for benzene) [2]. The method detection limit refers to the minimal gas phase concentration in ambient air required to load sufficient VOC mass into TGDE to perform δ 13 C analysis. Due to a different analytical procedure, the method detection limit associated with δ 37 Cl analysis was found to be 156±6μg/m 3 for TCE. Furthermore, the experimental results validated the relationship between the gas phase TCE and the progressive accumulation of dissolved TCE in the solvent during the sampling process. Accordingly, based on the air-solvent partitioning coefficient, the sampling methodology (e.g. sampling rate, sampling duration, amount of solvent) and the final TCE concentration in the solvent, the concentration of TCE in the gas phase prevailing during the sampling event can be determined. Moreover, the possibility to analyse for TCE concentration in the solvent after sampling (or other targeted VOCs) allows the field deployment of the sampling

  12. Optimal sample preparation for nanoparticle metrology (statistical size measurements) using atomic force microscopy

    International Nuclear Information System (INIS)

    Hoo, Christopher M.; Doan, Trang; Starostin, Natasha; West, Paul E.; Mecartney, Martha L.

    2010-01-01

    Optimal deposition procedures are determined for nanoparticle size characterization by atomic force microscopy (AFM). Accurate nanoparticle size distribution analysis with AFM requires non-agglomerated nanoparticles on a flat substrate. The deposition of polystyrene (100 nm), silica (300 and 100 nm), gold (100 nm), and CdSe quantum dot (2-5 nm) nanoparticles by spin coating was optimized for size distribution measurements by AFM. Factors influencing deposition include spin speed, concentration, solvent, and pH. A comparison using spin coating, static evaporation, and a new fluid cell deposition method for depositing nanoparticles is also made. The fluid cell allows for a more uniform and higher density deposition of nanoparticles on a substrate at laminar flow rates, making nanoparticle size analysis via AFM more efficient and also offers the potential for nanoparticle analysis in liquid environments.

  13. Optimized and validated high-performance liquid chromatography method for the determination of deoxynivalenol and aflatoxins in cereals.

    Science.gov (United States)

    Skendi, Adriana; Irakli, Maria N; Papageorgiou, Maria D

    2016-04-01

    A simple, sensitive and accurate analytical method was optimized and developed for the determination of deoxynivalenol and aflatoxins in cereals intended for human consumption using high-performance liquid chromatography with diode array and fluorescence detection and a photochemical reactor for enhanced detection. A response surface methodology, using a fractional central composite design, was carried out for optimization of the water percentage at the beginning of the run (X1, 80-90%), the level of acetonitrile at the end of gradient system (X2, 10-20%) with the water percentage fixed at 60%, and the flow rate (X3, 0.8-1.2 mL/min). The studied responses were the chromatographic peak area, the resolution factor and the time of analysis. Optimal chromatographic conditions were: X1 = 80%, X2 = 10%, and X3 = 1 mL/min. Following a double sample extraction with water and a mixture of methanol/water, mycotoxins were rapidly purified by an optimized solid-phase extraction protocol. The optimized method was further validated with respect to linearity (R(2) >0.9991), sensitivity, precision, and recovery (90-112%). The application to 23 commercial cereal samples from Greece showed contamination levels below the legally set limits, except for one maize sample. The main advantages of the developed method are the simplicity of operation and the low cost. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Population Pharmacokinetics of Gemcitabine and dFdU in Pancreatic Cancer Patients Using an Optimal Design, Sparse Sampling Approach.

    Science.gov (United States)

    Serdjebi, Cindy; Gattacceca, Florence; Seitz, Jean-François; Fein, Francine; Gagnière, Johan; François, Eric; Abakar-Mahamat, Abakar; Deplanque, Gael; Rachid, Madani; Lacarelle, Bruno; Ciccolini, Joseph; Dahan, Laetitia

    2017-06-01

    Gemcitabine remains a pillar in pancreatic cancer treatment. However, toxicities are frequently observed. Dose adjustment based on therapeutic drug monitoring might help decrease the occurrence of toxicities. In this context, this work aims at describing the pharmacokinetics (PK) of gemcitabine and its metabolite dFdU in pancreatic cancer patients and at identifying the main sources of their PK variability using a population PK approach, despite a sparse sampled-population and heterogeneous administration and sampling protocols. Data from 38 patients were included in the analysis. The 3 optimal sampling times were determined using KineticPro and the population PK analysis was performed on Monolix. Available patient characteristics, including cytidine deaminase (CDA) status, were tested as covariates. Correlation between PK parameters and occurrence of severe hematological toxicities was also investigated. A two-compartment model best fitted the gemcitabine and dFdU PK data (volume of distribution and clearance for gemcitabine: V1 = 45 L and CL1 = 4.03 L/min; for dFdU: V2 = 36 L and CL2 = 0.226 L/min). Renal function was found to influence gemcitabine clearance, and body surface area to impact the volume of distribution of dFdU. However, neither CDA status nor the occurrence of toxicities was correlated to PK parameters. Despite sparse sampling and heterogeneous administration and sampling protocols, population and individual PK parameters of gemcitabine and dFdU were successfully estimated using Monolix population PK software. The estimated parameters were consistent with previously published results. Surprisingly, CDA activity did not influence gemcitabine PK, which was explained by the absence of CDA-deficient patients enrolled in the study. This work suggests that even sparse data are valuable to estimate population and individual PK parameters in patients, which will be usable to individualize the dose for an optimized benefit to risk ratio.

  15. Open focused microwave-assisted sample preparation for rapid total and mercury species determination in environmental solid samples

    OpenAIRE

    Tseng, C. M.; Garraud, H.; Amouroux, D.; Donard, O. F. X.; de Diego, A.

    1998-01-01

    This paper describes rapid, simple microwave-assisted leaching/ digestion procedures for total and mercury species determination in sediment samples and biomaterials. An open focused microwave system allowed the sample preparation time to be dramatically reduced to only 24 min when a power of 40-80 W was applied. Quantitative leaching of methylmercury from sediments by HNO3 solution and complete dissolution of biomaterials by an alkaline solution, such as 25% TMAH solution, were obtained. Met...

  16. On the Determinants of Optimal Border Taxes for a Small Open Economy

    DEFF Research Database (Denmark)

    Munk, Knud Jørgen; Rasmussen, Bo Sandemann

    of the primary factor and domestic consumption of the export good cannot be taxed is nevertheless a constraint; this insight provides the key to understanding what determines the optimal tariff structure. The optimal border tax structure is derived for both exogenous and endogenous labour supply, and the results...... are interpreted in the spirit of the Corlett-Hague results for the optimal tax structure in a closed economy and compared with results from CGE models....

  17. Tracer techniques for urine volume determination and urine collection and sampling back-up system

    Science.gov (United States)

    Ramirez, R. V.

    1971-01-01

    The feasibility, functionality, and overall accuracy of the use of lithium were investigated as a chemical tracer in urine for providing a means of indirect determination of total urine volume by the atomic absorption spectrophotometry method. Experiments were conducted to investigate the parameters of instrumentation, tracer concentration, mixing times, and methods for incorporating the tracer material in the urine collection bag, and to refine and optimize the urine tracer technique to comply with the Skylab scheme and operational parameters of + or - 2% of volume error and + or - 1% accuracy of amount of tracer added to each container. In addition, a back-up method for urine collection and sampling system was developed and evaluated. This back-up method incorporates the tracer technique for volume determination in event of failure of the primary urine collection and preservation system. One chemical preservative was selected and evaluated as a contingency chemical preservative for the storage of urine in event of failure of the urine cooling system.

  18. Determination of human albumin in serum and urine samples by constant-energy synchronous fluorescence method.

    Science.gov (United States)

    Madrakian, Tayyebeh; Bagheri, Habibollah; Afkhami, Abbas

    2015-08-01

    A sensitive spectrofluorimetric method using constant-energy synchronous fluorescence technique is proposed for the determination of human albumin without separation. In this method, no reagent was used for enhancement of the fluorescence signal of albumin in the solution. Effects of some parameters, such as energy difference between excitation and emission monochromators (ΔE), emission and excitation slit widths and scan rate of wavelength were studied and the optimum conditions were established. For this purpose factorial design and response surface method were employed for optimization of the effective parameters on the fluorescence signal. The results showed that the scan rate of the wavelength has no significant effect on the analytical signal. The calibration curve was linear in the range 0.1-220.0 µg mL(-1) of albumin with a detection limit of 7.0 × 10(-3)  µg mL(-1). The relative standard deviations (RSD) for six replicate measurements of albumin were calculated as 2.2%, 1.7% and 1.3% for 0.5, 10.0 and 100.0 µg mL(-1) albumin, respectively. Furthermore the proposed method has been employed for the determination of albumin in human serum and urine samples. Copyright © 2014 John Wiley & Sons, Ltd.

  19. Foam generation and sample composition optimization for the FOAM-C experiment of the ISS

    Science.gov (United States)

    Carpy, R.; Picker, G.; Amann, B.; Ranebo, H.; Vincent-Bonnieu, S.; Minster, O.; Winter, J.; Dettmann, J.; Castiglione, L.; Höhler, R.; Langevin, D.

    2011-12-01

    End of 2009 and early 2010 a sealed cell, for foam generation and observation, has been designed and manufactured at Astrium Friedrichshafen facilities. With the use of this cell, different sample compositions of "wet foams" have been optimized for mixtures of chemicals such as water, dodecanol, pluronic, aethoxisclerol, glycerol, CTAB, SDS, as well as glass beads. This development is performed in the frame of the breadboarding development activities of the Experiment Container FOAM-C for operation in the ISS Fluid Science Laboratory (ISS). The sample cell supports multiple observation methods such as: Diffusing-Wave and Diffuse Transmission Spectrometry, Time Resolved Correlation Spectroscopy [1] and microscope observation, all of these methods are applied in the cell with a relatively small experiment volume 40).

  20. AMORE-HX: a multidimensional optimization of radial enhanced NMR-sampled hydrogen exchange

    International Nuclear Information System (INIS)

    Gledhill, John M.; Walters, Benjamin T.; Wand, A. Joshua

    2009-01-01

    The Cartesian sampled three-dimensional HNCO experiment is inherently limited in time resolution and sensitivity for the real time measurement of protein hydrogen exchange. This is largely overcome by use of the radial HNCO experiment that employs the use of optimized sampling angles. The significant practical limitation presented by use of three-dimensional data is the large data storage and processing requirements necessary and is largely overcome by taking advantage of the inherent capabilities of the 2D-FT to process selective frequency space without artifact or limitation. Decomposition of angle spectra into positive and negative ridge components provides increased resolution and allows statistical averaging of intensity and therefore increased precision. Strategies for averaging ridge cross sections within and between angle spectra are developed to allow further statistical approaches for increasing the precision of measured hydrogen occupancy. Intensity artifacts potentially introduced by over-pulsing are effectively eliminated by use of the BEST approach

  1. Distribution of the Determinant of the Sample Correlation Matrix: Monte Carlo Type One Error Rates.

    Science.gov (United States)

    Reddon, John R.; And Others

    1985-01-01

    Computer sampling from a multivariate normal spherical population was used to evaluate the type one error rates for a test of sphericity based on the distribution of the determinant of the sample correlation matrix. (Author/LMO)

  2. Analytical strategies for uranium determination in natural water and industrial effluents samples

    International Nuclear Information System (INIS)

    Santos, Juracir Silva

    2011-01-01

    The work was developed under the project 993/2007 - 'Development of analytical strategies for uranium determination in environmental and industrial samples - Environmental monitoring in the Caetite city, Bahia, Brazil' and made possible through a partnership established between Universidade Federal da Bahia and the Comissao Nacional de Energia Nuclear. Strategies were developed to uranium determination in natural water and effluents of uranium mine. The first one was a critical evaluation of the determination of uranium by inductively coupled plasma optical emission spectrometry (ICP OES) performed using factorial and Doehlert designs involving the factors: acid concentration, radio frequency power and nebuliser gas flow rate. Five emission lines were simultaneously studied (namely: 367.007, 385.464, 385.957, 386.592 and 409.013 nm), in the presence of HN0 3 , H 3 C 2 00H or HCI. The determinations in HN0 3 medium were the most sensitive. Among the factors studied, the gas flow rate was the most significant for the five emission lines. Calcium caused interference in the emission intensity for some lines and iron did not interfere (at least up to 10 mg L -1 ) in the five lines studied. The presence of 13 other elements did not affect the emission intensity of uranium for the lines chosen. The optimized method, using the line at 385.957 nm, allows the determination of uranium with limit of quantification of 30 μg L -1 and precision expressed as RSD lower than 2.2% for uranium concentrations of either 500 and 1000 μg L -1 . In second one, a highly sensitive flow-based procedure for uranium determination in natural waters is described. A 100-cm optical path flow cell based on a liquid-core waveguide (LCW) was exploited to increase sensitivity of the arsenazo 111 method, aiming to achieve the limits established by environmental regulations. The flow system was designed with solenoid micro-pumps in order to improve mixing and minimize reagent consumption, as well as

  3. Determination of mercury in biologycal samples by radiochemical neutron activation analysis

    International Nuclear Information System (INIS)

    Suc, N.V.

    1989-01-01

    The radiochemical neutron activation analysis was applied to determine contents of mercury in biological samples. Samples were digested in mixing of H 2 SO 4 and HNO 3 acid. After extraction of mercury by Ni-Ditiodietylphosphoric acid in carbontetrachloride, mercury was back extracted by 5% KI solution. Contents of mercury from five samples of fish was determined by this method. The accuracy of the method was checked by comparing it with NBS standard samples and results are good agreement

  4. Quantitative method of determining beryllium or a compound thereof in a sample

    Science.gov (United States)

    McCleskey, T. Mark; Ehler, Deborah S.; John, Kevin D.; Burrell, Anthony K.; Collis, Gavin E.; Minogue, Edel M.; Warner, Benjamin P.

    2010-08-24

    A method of determining beryllium or a beryllium compound thereof in a sample, includes providing a sample suspected of comprising beryllium or a compound thereof, extracting beryllium or a compound thereof from the sample by dissolving in a solution, adding a fluorescent indicator to the solution to thereby bind any beryllium or a compound thereof to the fluorescent indicator, and determining the presence or amount of any beryllium or a compound thereof in the sample by measuring fluorescence.

  5. Optimal sampling strategies to assess inulin clearance in children by the inulin single-injection method

    NARCIS (Netherlands)

    van Rossum, Lyonne K.; Mathot, Ron A. A.; Cransberg, Karlien; Vulto, Arnold G.

    2003-01-01

    Glomerular filtration rate in patients can be determined by estimating the plasma clearance of inulin with the single-injection method. In this method, a single bolus injection of inulin is administered and several blood samples are collected. For practical and convenient application of this method

  6. Optimization of multi-channel neutron focusing guides for extreme sample environments

    International Nuclear Information System (INIS)

    Di Julio, D D; Lelièvre-Berna, E; Andersen, K H; Bentley, P M; Courtois, P

    2014-01-01

    In this work, we present and discuss simulation results for the design of multichannel neutron focusing guides for extreme sample environments. A single focusing guide consists of any number of supermirror-coated curved outer channels surrounding a central channel. Furthermore, a guide is separated into two sections in order to allow for extension into a sample environment. The performance of a guide is evaluated through a Monte-Carlo ray tracing simulation which is further coupled to an optimization algorithm in order to find the best possible guide for a given situation. A number of population-based algorithms have been investigated for this purpose. These include particle-swarm optimization, artificial bee colony, and differential evolution. The performance of each algorithm and preliminary results of the design of a multi-channel neutron focusing guide using these methods are described. We found that a three-channel focusing guide offered the best performance, with a gain factor of 2.4 compared to no focusing guide, for the design scenario investigated in this work.

  7. Bayesian assessment of the expected data impact on prediction confidence in optimal sampling design

    Science.gov (United States)

    Leube, P. C.; Geiges, A.; Nowak, W.

    2012-02-01

    Incorporating hydro(geo)logical data, such as head and tracer data, into stochastic models of (subsurface) flow and transport helps to reduce prediction uncertainty. Because of financial limitations for investigation campaigns, information needs toward modeling or prediction goals should be satisfied efficiently and rationally. Optimal design techniques find the best one among a set of investigation strategies. They optimize the expected impact of data on prediction confidence or related objectives prior to data collection. We introduce a new optimal design method, called PreDIA(gnosis) (Preposterior Data Impact Assessor). PreDIA derives the relevant probability distributions and measures of data utility within a fully Bayesian, generalized, flexible, and accurate framework. It extends the bootstrap filter (BF) and related frameworks to optimal design by marginalizing utility measures over the yet unknown data values. PreDIA is a strictly formal information-processing scheme free of linearizations. It works with arbitrary simulation tools, provides full flexibility concerning measurement types (linear, nonlinear, direct, indirect), allows for any desired task-driven formulations, and can account for various sources of uncertainty (e.g., heterogeneity, geostatistical assumptions, boundary conditions, measurement values, model structure uncertainty, a large class of model errors) via Bayesian geostatistics and model averaging. Existing methods fail to simultaneously provide these crucial advantages, which our method buys at relatively higher-computational costs. We demonstrate the applicability and advantages of PreDIA over conventional linearized methods in a synthetic example of subsurface transport. In the example, we show that informative data is often invisible for linearized methods that confuse zero correlation with statistical independence. Hence, PreDIA will often lead to substantially better sampling designs. Finally, we extend our example to specifically

  8. Regional gray matter abnormalities in patients with schizophrenia determined with optimized voxel-based morphometry

    Science.gov (United States)

    Guo, XiaoJuan; Yao, Li; Jin, Zhen; Chen, Kewei

    2006-03-01

    This study examined regional gray matter abnormalities across the whole brain in 19 patients with schizophrenia (12 males and 7 females), comparing with 11 normal volunteers (7 males and 4 females). The customized brain templates were created in order to improve spatial normalization and segmentation. Then automated preprocessing of magnetic resonance imaging (MRI) data was conducted using optimized voxel-based morphometry (VBM). The statistical voxel based analysis was implemented in terms of two-sample t-test model. Compared with normal controls, regional gray matter concentration in patients with schizophrenia was significantly reduced in the bilateral superior temporal gyrus, bilateral middle frontal and inferior frontal gyrus, right insula, precentral and parahippocampal areas, left thalamus and hypothalamus as well as, however, significant increases in gray matter concentration were not observed across the whole brain in the patients. This study confirms and extends some earlier findings on gray matter abnormalities in schizophrenic patients. Previous behavior and fMRI researches on schizophrenia have suggested that cognitive capacity decreased and self-conscious weakened in schizophrenic patients. These regional gray matter abnormalities determined through structural MRI with optimized VBM may be potential anatomic underpinnings of schizophrenia.

  9. Novel synthesis of nanocomposite for the extraction of Sildenafil Citrate (Viagra) from water and urine samples: Process screening and optimization.

    Science.gov (United States)

    Asfaram, Arash; Ghaedi, Mehrorang; Purkait, Mihir Kumar

    2017-09-01

    A sensitive analytical method is investigated to concentrate and determine trace level of Sildenafil Citrate (SLC) present in water and urine samples. The method is based on a sample treatment using dispersive solid-phase micro-extraction (DSPME) with laboratory-made Mn@ CuS/ZnS nanocomposite loaded on activated carbon (Mn@ CuS/ZnS-NCs-AC) as a sorbent for the target analyte. The efficiency was enhanced by ultrasound-assisted (UA) with dispersive nanocomposite solid-phase micro-extraction (UA-DNSPME). Four significant variables affecting SLC recovery like; pH, eluent volume, sonication time and adsorbent mass were selected by the Plackett-Burman design (PBD) experiments. These selected factors were optimized by the central composite design (CCD) to maximize extraction of SLC. The results exhibited that the optimum conditions for maximizing extraction of SLC were 6.0 pH, 300μL eluent (acetonitrile) volume, 10mg of adsorbent and 6min sonication time. Under optimized conditions, virtuous linearity of SLC was ranged from 30 to 4000ngmL -1 with R 2 of 0.99. The limit of detection (LOD) was 2.50ngmL -1 and the recoveries at two spiked levels were ranged from 97.37 to 103.21% with the relative standard deviation (RSD) less than 4.50% (n=15). The enhancement factor (EF) was 81.91. The results show that the combination UAE with DNSPME is a suitable method for the determination of SLC in water and urine samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Comparison of fluorescence-enhancing reagents and optimization of laser fluorimetric technique for the determination of dissolved uranium

    International Nuclear Information System (INIS)

    Ceren Kuetahyali; Joaquin Cobos; Rondinella, V.V.

    2011-01-01

    Results from tests aimed at optimizing an instrumental procedure for the direct and fast determination of uranium in solution by laser fluorescence are presented. A comparison of sample fluorescence measured using different fluorescence enhancing reagents was performed: sodium pyrophosphate, orthophosphoric acid, sulphuric acid and a commercially available fluorescence enhancer were tested for the determination of uranium. From the experimental results, 0.01 M Na 4 P 2 O 7 x 10H 2 O showed the best performance. Effects of reagent pH, different matrices, different concentrations of dissolved Th, and sample volume were investigated. Applications of the improved procedure for the determination of uranium in samples arising from UO 2 -based high level nuclear waste dissolution studies are described. (author)

  11. Determination of an Optimal Control Strategy for a Generic Surface Vehicle

    Science.gov (United States)

    2014-06-18

    TERMS Autonomous Vehicles Boundary Value Problem Dynamic Programming Surface Vehicles Optimal Control Path Planning 16...to follow prescribed motion trajectories. In particular, for autonomous vehicles , this motion trajectory is given by the determination of the

  12. Extraction and Determination of Crocin in Saffron Samples by Dispersive Liquid-Liquid Microextraction

    Directory of Open Access Journals (Sweden)

    Somayeh Heydari

    2016-11-01

    Full Text Available The main component responsible for color in saffron is crocin with the chemical formula of C44H64O24. Crocin is one of several carotenoids in nature that is soluble in water. This solubility is one of the reasons for its widespread usage as a colorant in food and medicine compared to other carotenoids. The coloring strength of saffron is one of the major factors that determine the quality of the saffron stigma. It will be evaluated with measuring of crocin. Microextraction is the newest and easiest method that can be successfully applied for the preconcentration and separation of crocin in saffron samples. The advantages of this method are faster, cheaper and easier analysis by UV-Vis spectrophotometry in measurement of crocin compared to the chromatographic analysis methods. The studies showed that the type and volume of disperser and extractant solvent have a significant effect on the efficiency of crocin extraction. In this work, acetone as the disperser solvent and dichlorometane as the extractant solvent were found to be suitable combinations. Under the optimal conditions, the calibration curve was linear in the range of 0.15-0.00001 μg mL-1 and the limit of detection (LOD was calculated based on 3 Sb/m (where, Sb and m are the standard deviation of the blank and slop ratio of the calibration curve respectively was 0.000008 μg mL-1. The procedure was applied to saffron samples and the good recovery percent for the saffron samples was obtained.

  13. Geometry and Topology Optimization of Statically Determinate Beams under Fixed and Most Unfavorably Distributed Load

    Directory of Open Access Journals (Sweden)

    Agata Kozikowska

    Full Text Available Abstract The paper concerns topology and geometry optimization of statically determinate beams with an arbitrary number of pin supports. The beams are simultaneously exposed to uniform dead load and arbitrarily distributed live load and optimized for the absolute maximum bending moment. First, all the beams with fixed topology are subjected to geometrical optimization by genetic algorithm. Strict mathematical formulas for calculation of optimal geometrical parameters are found for all topologies and any ratio of dead to live load. Then beams with the same minimal values of the objective function and different topologies are classified into groups called topological classes. The detailed characteristics of these classes are described.

  14. Experimental-calculation technique for Ksub(IC) determination using the samples of decreased dimensions

    International Nuclear Information System (INIS)

    Vinokurov, V.A.; Dymshits, A.V.; Pirusskij, M.V.; Ovsyannikov, B.M.; Kononov, V.V.

    1981-01-01

    A possibility to decrease the size of samples, which is necessary for the reliable determination of fractUre toughness Ksub(1c), is established. The dependences of crack-resistance caracteristics on the sample dimensions are determined experimentally. The static bending tests are made using the 1251 model of ''Instron'' installation with a specially designed device. The samples of the 20KhNMF steel have been tested. It is shown that the Ksub(1c) value, determined for the samples with the largest netto cross section (50x100 rm), is considerably lower than Ksub(1c) values, determined for the samples with the decreased sizes. it is shown that the developed experimental-calculated method of Ksub(1c) determination can be practically used for the samples of the decreased sizes with the introduction of the corresponding amendment coefficient [ru

  15. Immunosuppressant therapeutic drug monitoring by LC-MS/MS: workflow optimization through automated processing of whole blood samples.

    Science.gov (United States)

    Marinova, Mariela; Artusi, Carlo; Brugnolo, Laura; Antonelli, Giorgia; Zaninotto, Martina; Plebani, Mario

    2013-11-01

    Although, due to its high specificity and sensitivity, LC-MS/MS is an efficient technique for the routine determination of immunosuppressants in whole blood, it involves time-consuming manual sample preparation. The aim of the present study was therefore to develop an automated sample-preparation protocol for the quantification of sirolimus, everolimus and tacrolimus by LC-MS/MS using a liquid handling platform. Six-level commercially available blood calibrators were used for assay development, while four quality control materials and three blood samples from patients under immunosuppressant treatment were employed for the evaluation of imprecision. Barcode reading, sample re-suspension, transfer of whole blood samples into 96-well plates, addition of internal standard solution, mixing, and protein precipitation were performed with a liquid handling platform. After plate filtration, the deproteinised supernatants were submitted for SPE on-line. The only manual steps in the entire process were de-capping of the tubes, and transfer of the well plates to the HPLC autosampler. Calibration curves were linear throughout the selected ranges. The imprecision and accuracy data for all analytes were highly satisfactory. The agreement between the results obtained with manual and those obtained with automated sample preparation was optimal (n=390, r=0.96). In daily routine (100 patient samples) the typical overall total turnaround time was less than 6h. Our findings indicate that the proposed analytical system is suitable for routine analysis, since it is straightforward and precise. Furthermore, it incurs less manual workload and less risk of error in the quantification of whole blood immunosuppressant concentrations than conventional methods. © 2013.

  16. Determination of total mercury for marine environmental monitoring studies by solid sampling continuum source high resolution atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Mandjukov, Petko; Orani, Anna Maria; Han, Eunmi; Vassileva, Emilia, E-mail: e.vasileva-veleva@iaea.org

    2015-01-01

    The most critical step in almost all commonly used analytical procedures for Hg determination is the sample preparation due to its extreme volatility. One of the possible solutions of this problem is the application of methods for direct analysis of solid samples. The possibilities for solid sampling high resolution continuum source atomic absorption spectrometry (HR CS AAS) determination of total mercury in various marine environmental samples e.g. sediments and biota are object of the present study. The instrumental parameters were optimized in order to obtain reproducible and interference free analytical signal. A calibration technique based on the use of solid standard certified reference materials similar to the nature of the analyzed sample was developed and applied to various CRMs and real samples. This technique allows simple and reliable evaluation of the uncertainty of the result and the metrological characteristics of the method. A validation approach in line with the requirements of ISO 17025 standard and Eurachem guidelines was followed. With this in mind, selectivity, working range (0.06 to 25 ng for biota and 0.025 to 4 ng for sediment samples, expressed as total Hg) linearity (confirmed by Student's t-test), bias (1.6–4.3%), repeatability (4–9%), reproducibility (9–11%), and absolute limit of detection (0.025 ng for sediment, 0.096 ng for marine biota) were systematically assessed using solid CRMs. The relative expanded uncertainty was estimated at 15% for sediment sample and 8.5% for marine biota sample (k = 2). Demonstration of traceability of measurement results is also presented. The potential of the proposed analytical procedure, based on solid sampling HR CS AAS technique was demonstrated by direct analysis of sea sediments form the Caribbean region and various CRMs. Overall, the use of solid sampling HR CS AAS permits obtaining significant advantages for the determination of this complex analyte in marine samples, such as

  17. Modeling Optimal Cutoffs for the Brazilian Household Food Insecurity Measurement Scale in a Nationwide Representative Sample.

    Science.gov (United States)

    Interlenghi, Gabriela S; Reichenheim, Michael E; Segall-Corrêa, Ana M; Pérez-Escamilla, Rafael; Moraes, Claudia L; Salles-Costa, Rosana

    2017-07-01

    Background: This is the second part of a model-based approach to examine the suitability of the current cutoffs applied to the raw score of the Brazilian Household Food Insecurity Measurement Scale [Escala Brasileira de Insegurança Alimentar (EBIA)]. The approach allows identification of homogeneous groups who correspond to severity levels of food insecurity (FI) and, by extension, discriminant cutoffs able to accurately distinguish these groups. Objective: This study aims to examine whether the model-based approach for identifying optimal cutoffs first implemented in a local sample is replicated in a countrywide representative sample. Methods: Data were derived from the Brazilian National Household Sample Survey of 2013 ( n = 116,543 households). Latent class factor analysis (LCFA) models from 2 to 5 classes were applied to the scale's items to identify the number of underlying FI latent classes. Next, identification of optimal cutoffs on the overall raw score was ascertained from these identified classes. Analyses were conducted in the aggregate data and by macroregions. Finally, model-based classifications (latent classes and groupings identified thereafter) were contrasted to the traditionally used classification. Results: LCFA identified 4 homogeneous groups with a very high degree of class separation (entropy = 0.934-0.975). The following cutoffs were identified in the aggregate data: between 1 and 2 (1/2), 5 and 6 (5/6), and 10 and 11 (10/11) in households with children and/or adolescents category emerged consistently in all analyses. Conclusions: Nationwide findings corroborate previous local evidence that households with an overall score of 1 are more akin to those scoring negative on all items. These results may contribute to guide experts' and policymakers' decisions on the most appropriate EBIA cutoffs. © 2017 American Society for Nutrition.

  18. An optimized Line Sampling method for the estimation of the failure probability of nuclear passive systems

    International Nuclear Information System (INIS)

    Zio, E.; Pedroni, N.

    2010-01-01

    The quantitative reliability assessment of a thermal-hydraulic (T-H) passive safety system of a nuclear power plant can be obtained by (i) Monte Carlo (MC) sampling the uncertainties of the system model and parameters, (ii) computing, for each sample, the system response by a mechanistic T-H code and (iii) comparing the system response with pre-established safety thresholds, which define the success or failure of the safety function. The computational effort involved can be prohibitive because of the large number of (typically long) T-H code simulations that must be performed (one for each sample) for the statistical estimation of the probability of success or failure. In this work, Line Sampling (LS) is adopted for efficient MC sampling. In the LS method, an 'important direction' pointing towards the failure domain of interest is determined and a number of conditional one-dimensional problems are solved along such direction; this allows for a significant reduction of the variance of the failure probability estimator, with respect, for example, to standard random sampling. Two issues are still open with respect to LS: first, the method relies on the determination of the 'important direction', which requires additional runs of the T-H code; second, although the method has been shown to improve the computational efficiency by reducing the variance of the failure probability estimator, no evidence has been given yet that accurate and precise failure probability estimates can be obtained with a number of samples reduced to below a few hundreds, which may be required in case of long-running models. The work presented in this paper addresses the first issue by (i) quantitatively comparing the efficiency of the methods proposed in the literature to determine the LS important direction; (ii) employing artificial neural network (ANN) regression models as fast-running surrogates of the original, long-running T-H code to reduce the computational cost associated to the

  19. Population Pharmacokinetics and Optimal Sampling Strategy for Model-Based Precision Dosing of Melphalan in Patients Undergoing Hematopoietic Stem Cell Transplantation.

    Science.gov (United States)

    Mizuno, Kana; Dong, Min; Fukuda, Tsuyoshi; Chandra, Sharat; Mehta, Parinda A; McConnell, Scott; Anaissie, Elias J; Vinks, Alexander A

    2018-05-01

    High-dose melphalan is an important component of conditioning regimens for patients undergoing hematopoietic stem cell transplantation. The current dosing strategy based on body surface area results in a high incidence of oral mucositis and gastrointestinal and liver toxicity. Pharmacokinetically guided dosing will individualize exposure and help minimize overexposure-related toxicity. The purpose of this study was to develop a population pharmacokinetic model and optimal sampling strategy. A population pharmacokinetic model was developed with NONMEM using 98 observations collected from 15 adult patients given the standard dose of 140 or 200 mg/m 2 by intravenous infusion. The determinant-optimal sampling strategy was explored with PopED software. Individual area under the curve estimates were generated by Bayesian estimation using full and the proposed sparse sampling data. The predictive performance of the optimal sampling strategy was evaluated based on bias and precision estimates. The feasibility of the optimal sampling strategy was tested using pharmacokinetic data from five pediatric patients. A two-compartment model best described the data. The final model included body weight and creatinine clearance as predictors of clearance. The determinant-optimal sampling strategies (and windows) were identified at 0.08 (0.08-0.19), 0.61 (0.33-0.90), 2.0 (1.3-2.7), and 4.0 (3.6-4.0) h post-infusion. An excellent correlation was observed between area under the curve estimates obtained with the full and the proposed four-sample strategy (R 2  = 0.98; p strategy promises to achieve the target area under the curve as part of precision dosing.

  20. Optimized measurement of radium-226 concentration in liquid samples with radon-222 emanation

    International Nuclear Information System (INIS)

    Perrier, Frédéric; Aupiais, Jean; Girault, Frédéric; Przylibski, Tadeusz A.; Bouquerel, Hélène

    2016-01-01

    Measuring radium-226 concentration in liquid samples using radon-222 emanation remains competitive with techniques such as liquid scintillation, alpha or mass spectrometry. Indeed, we show that high-precision can be obtained without air circulation, using an optimal air to liquid volume ratio and moderate heating. Cost-effective and efficient measurement of radon concentration is achieved by scintillation flasks and sufficiently long counting times for signal and background. More than 400 such measurements were performed, including 39 dilution experiments, a successful blind measurement of six reference test solutions, and more than 110 repeated measurements. Under optimal conditions, uncertainties reach 5% for an activity concentration of 100 mBq L"−"1 and 10% for 10 mBq L"−"1. While the theoretical detection limit predicted by Monte Carlo simulation is around 3 mBq L"−"1, a conservative experimental estimate is rather 5 mBq L"−"1, corresponding to 0.14 fg g"−"1. The method was applied to 47 natural waters, 51 commercial waters, and 17 wine samples, illustrating that it could be an option for liquids that cannot be easily measured by other methods. Counting of scintillation flasks can be done in remote locations in absence of electricity supply, using a solar panel. Thus, this portable method, which has demonstrated sufficient accuracy for numerous natural liquids, could be useful in geological and environmental problems, with the additional benefit that it can be applied in isolated locations and in circumstances when samples cannot be transported. - Highlights: • Radium-226 concentration measured with optimized accumulation in a container. • Radon-222 in air measured precisely with scintillation flasks and long countings. • Method tested by repetition tests, dilution experiments, and successful blind tests. • Estimated conservative detection limit without pre-concentration is 5 mBq L"−"1. • Method is portable, cost

  1. Determination of rare earth elements in natural water samples – A review of sample separation, preconcentration and direct methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Andrew, E-mail: afisher@plymouth.ac.uk [School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth, Devon, PL4 8AA (United Kingdom); Kara, Derya [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100, Balikesir (Turkey)

    2016-09-07

    This review discusses and compares the methods given for the determination of rare earth elements (REE) in natural water samples, including sea, river, lake, tap, ground and waste waters as well as Antarctic ice. Since REE are at very low concentrations in natural waters, numerous different preconcentration methods have been proposed to enable their measurement. These include liquid liquid extraction, dispersive liquid-liquid micro-extraction and solidified floating drop micro-extraction. In addition to liquid-liquid extraction methods, solid phase extraction using commercial resins, resins made in-house, silica-based exchange materials and other solid media is also discussed. These and other techniques such as precipitation/co-precipitation and flotation are compared in terms of speed, preconcentration factors achieved, precision, accuracy and limits of detection (LOD). Some papers have discussed the direct determination of REE in these sample types. Some have used specialised sample introduction systems such as ultrasonic nebulization whereas others have used a standard sample introduction system coupled with inductively coupled plasma mass spectrometry (ICP-MS) detection. These direct methods have also been discussed and compared. - Highlights: • The determination of rare earth elements in waters is reviewed. • Assorted preconcentration techniques are discussed and evaluated. • Detection techniques include atomic spectrometry, potentiometry and spectrophotometry. • Special nebulisers and electrothermal vaporization approaches are reviewed.

  2. Determination of cobalt in biological samples by line-source and high-resolution continuum source graphite furnace atomic absorption spectrometry using solid sampling or alkaline treatment

    International Nuclear Information System (INIS)

    Ribeiro, Anderson Schwingel; Vieira, Mariana Antunes; Furtado da Silva, Alessandra; Borges, Daniel L. Gallindo; Welz, Bernhard; Heitmann, Uwe; Curtius, Adilson Jose

    2005-01-01

    Two procedures for the determination of Co in biological samples by graphite furnace atomic absorption spectrometry (GF AAS) were compared: solid sampling (SS) and alkaline treatment with tetramethylammonium hydroxide (TMAH) using two different instruments for the investigation: a conventional line-source (LS) atomic absorption spectrometer and a prototype high-resolution continuum source atomic absorption spectrometer. For the direct introduction of the solid samples, certified reference materials (CRM) were ground to a particle size ≤50 μm. Alkaline treatment was carried out by placing about 250 mg of the sample in polypropylene flasks, adding 2 mL of 25% m/v tetramethylammonium hydroxide and de-ionized water. Due to its unique capacity of providing a 3-D spectral plot, a high-resolution continuum source (HR-CS) graphite furnace atomic absorption spectrometry was used as a tool to evaluate potential spectral interferences, including background absorption for both sample introduction procedures, revealing that a continuous background preceded the atomic signal for pyrolysis temperatures lower than 700 deg. C. Molecular absorption bands with pronounced rotational fine structure appeared for atomization temperatures >1800 deg. C probably as a consequence of the formation of PO. After optimization had been carried out using high resolution continuum source atomic absorption spectrometry, the optimized conditions were adopted also for line-source atomic absorption spectrometry. Six biological certified reference materials were analyzed, with calibration against aqueous standards, resulting in agreement with the certified values (according to the t-test for a 95% confidence level) and in detection limits as low as 5 ng g -1

  3. Carotenoid determination in recent marine sediments - practical problems during sample preparation and HPLC analysis

    Directory of Open Access Journals (Sweden)

    Magdalena Krajewska

    2017-05-01

    Full Text Available An analytical procedure for the analysis of carotenoids in marine sediments rich in organic matter has been developed. Analysis of these compounds is difficult; the application of methods used by other authors required optimization for the samples studied here. The analytical procedure involved multiple ultrasound-assisted extraction with acetone followed by liquid-liquid extraction (acetone extract:benzene:water - 15:1:10 v/v/v and HPLC analysis. The influence of column temperature on pigment separation and the quantification method were investigated – a temperature of 5 °C was selected for the Lichrospher 100 RP-18e column. The pigments in the sediment extract were quantified using a method based on HPLC analysis (at 450 nm and spectrophotometric measurements (at 450 nm, and extinction coefficients were determined for standard solutions at this wavelength. It is very important to use the value of the extinction coefficient appropriate to the wavelength at which the detection of carotenoids was carried out.

  4. Liquid chromatographic determination of pioglitazone in pharmaceuticals, serum and urine samples

    International Nuclear Information System (INIS)

    Abro, K.; Memon, N.; Bhanger, M.I.; Mahesar, S.A.; Parveen, S.

    2011-01-01

    A rapid and reliable analytical method based on high-performance liquid chromatography (HPLC) with UV detection (221 nm) has been developed for the determination of the anti-hyper glycemic agent Pioglitazone in pharmaceutical formulations and biological fluids (serum and urine) after clean-up with solid-phase extraction. Chromatographic separation was achieved with a Chromolith Performance RP-18e (10 4.6mm) column using mobile phase composition of acetonitrile: mixed phosphate buffer (pH 2.5; 10mM) (30:70, v/v) with a flow rate of 2.0mL/min. The total run time was 2 min. under optimized conditions. The calibration curve was found to be linear in the range of 1-10 mu g mL/sup -1/ with regression coefficient of 0.9996, and the lower limit of detection 72 ng/20 mu L injection. The method has been validated for the system suitability, linearity, precision and accuracy, limits of detection, specificity, stability and robustness. The %recovery of Pioglitazone in pharmaceutical formulations was found to be 104.7%. The assay has been applied successfully to the pharmaceutical Tablet samples and biological fluids (serum and urine) of healthy volunteers. (author)

  5. Correction for sample self-absorption in activity determination by gamma spectrometry

    International Nuclear Information System (INIS)

    Galloway, R.B.

    1991-01-01

    Gamma ray spectrometry is a convenient method of determining the activity of the radioactive components in environmental samples. Commonly samples vary in gamma absorption or differ in absorption from the calibration standards available, so that accurate correction for self-absorption in the sample is essential. A versatile correction procedure is described. (orig.)

  6. Application of immunoaffinity columns for different food item samples preparation in micotoxins determination

    Directory of Open Access Journals (Sweden)

    Ćurčić Marijana

    2016-01-01

    Full Text Available In analytical methods used for monitoring of what special attention is paid to sample preparation. Therefore, the objective of this study was testing the efficiency of immunoaffinity columns (IAC that are based on solid phase extraction principles used for samples preparation in determining aflatoxins and ochratoxins. Aflatoxins and ochratoxins concentrations were determined in totally 56 samples of food items: wheat, corn, rice, barley and other grains (19 samples, flour and flour products from grain and additives for the bakery industry (7 samples, fruits and vegetables (3 samples, hazelnut, walnut, almond, coconut flour (4 samples, roasted cocoa beans, peanuts, tea, coffee (16 samples, spices (4 samples and meat and meat products (4 samples. Obtained results indicate advantage of IAC use for sample preparation based on enhanced specificity due to binding of extracted molecules to incorporated specific antibodies and rinsing the rest molecules from sample which could interfere with further analysis. Additional advantage is the usage of small amount of organic solvents and consequently decreased exposure of staff who conduct micotoxins determination. Of special interest is increase in method sensitivity since limit of quantification for aflatoxins and ochratoxins determination method is lower than maximal allowed concentration of these toxines prescribed by national rule book.

  7. Determination of selected metals in coal samples from Lafia-Obi and ...

    African Journals Online (AJOL)

    coal samples were determined using atomic absorption spectroscopy (AAS). All the samples have comparable chromium and copper contents, while iron, aluminum, magnesium and potassium content vary to some extent. Metals concentrations in both Lafia-Obi and Chikila coal samples are within the limits allowed by the ...

  8. Determination of rhenium in geologic samples of sandstone-type uranium deposit

    International Nuclear Information System (INIS)

    Li Yanan; Wang Xiuqin; Yin Jinshuang

    1997-01-01

    The thiourea colorimetry method suitable for the determination of samples with rhenium content higher than 5 μg/g is described. The method is characterized by many advantages: stability of analytical results, simplicity and cheapness of reagent, and wide range of analysed samples. The catalytic colorimetry is also applied to determine trace rhenium meeting the demand for comprehensive appraisal of prospecting and exploration, recovery and utilization of rhenium. This method can also be applied to analyse rhenium of other samples

  9. Evaluation and optimization of DNA extraction and purification procedures for soil and sediment samples.

    Science.gov (United States)

    Miller, D N; Bryant, J E; Madsen, E L; Ghiorse, W C

    1999-11-01

    We compared and statistically evaluated the effectiveness of nine DNA extraction procedures by using frozen and dried samples of two silt loam soils and a silt loam wetland sediment with different organic matter contents. The effects of different chemical extractants (sodium dodecyl sulfate [SDS], chloroform, phenol, Chelex 100, and guanadinium isothiocyanate), different physical disruption methods (bead mill homogenization and freeze-thaw lysis), and lysozyme digestion were evaluated based on the yield and molecular size of the recovered DNA. Pairwise comparisons of the nine extraction procedures revealed that bead mill homogenization with SDS combined with either chloroform or phenol optimized both the amount of DNA extracted and the molecular size of the DNA (maximum size, 16 to 20 kb). Neither lysozyme digestion before SDS treatment nor guanidine isothiocyanate treatment nor addition of Chelex 100 resin improved the DNA yields. Bead mill homogenization in a lysis mixture containing chloroform, SDS, NaCl, and phosphate-Tris buffer (pH 8) was found to be the best physical lysis technique when DNA yield and cell lysis efficiency were used as criteria. The bead mill homogenization conditions were also optimized for speed and duration with two different homogenizers. Recovery of high-molecular-weight DNA was greatest when we used lower speeds and shorter times (30 to 120 s). We evaluated four different DNA purification methods (silica-based DNA binding, agarose gel electrophoresis, ammonium acetate precipitation, and Sephadex G-200 gel filtration) for DNA recovery and removal of PCR inhibitors from crude extracts. Sephadex G-200 spin column purification was found to be the best method for removing PCR-inhibiting substances while minimizing DNA loss during purification. Our results indicate that for these types of samples, optimum DNA recovery requires brief, low-speed bead mill homogenization in the presence of a phosphate-buffered SDS-chloroform mixture, followed

  10. A preconcentration system for determination of copper and nickel in water and food samples employing flame atomic absorption spectrometry.

    Science.gov (United States)

    Tuzen, Mustafa; Soylak, Mustafa; Citak, Demirhan; Ferreira, Hadla S; Korn, Maria G A; Bezerra, Marcos A

    2009-03-15

    A separation/preconcentration procedure using solid phase extraction has been proposed for the flame atomic absorption spectrometric determination of copper and nickel at trace level in food samples. The solid phase is Dowex Optipore SD-2 resin contained on a minicolumn, where analyte ions are sorbed as 5-methyl-4-(2-thiazolylazo) resorcinol chelates. After elution using 1 mol L(-1) nitric acid solution, the analytes are determinate employing flame atomic absorption spectrometry. The optimization step was performed using a full two-level factorial design and the variables studied were: pH, reagent concentration (RC) and amount of resin on the column (AR). Under the experimental conditions established in the optimization step, the procedure allows the determination of copper and nickel with limit of detection of 1.03 and 1.90 microg L(-1), respectively and precision of 7 and 8%, for concentrations of copper and nickel of 200 microg L(-1). The effect of matrix ions was also evaluated. The accuracy was confirmed by analyzing of the followings certified reference materials: NIST SRM 1515 Apple leaves and GBW 07603 Aquatic and Terrestrial Biological Products. The developed method was successfully applied for the determination of copper and nickel in real samples including human hair, chicken meat, black tea and canned fish.

  11. A preconcentration system for determination of copper and nickel in water and food samples employing flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Tuzen, Mustafa; Soylak, Mustafa; Citak, Demirhan; Ferreira, Hadla S.; Korn, Maria G.A.; Bezerra, Marcos A.

    2009-01-01

    A separation/preconcentration procedure using solid phase extraction has been proposed for the flame atomic absorption spectrometric determination of copper and nickel at trace level in food samples. The solid phase is Dowex Optipore SD-2 resin contained on a minicolumn, where analyte ions are sorbed as 5-methyl-4-(2-thiazolylazo) resorcinol chelates. After elution using 1 mol L -1 nitric acid solution, the analytes are determinate employing flame atomic absorption spectrometry. The optimization step was performed using a full two-level factorial design and the variables studied were: pH, reagent concentration (RC) and amount of resin on the column (AR). Under the experimental conditions established in the optimization step, the procedure allows the determination of copper and nickel with limit of detection of 1.03 and 1.90 μg L -1 , respectively and precision of 7 and 8%, for concentrations of copper and nickel of 200 μg L -1 . The effect of matrix ions was also evaluated. The accuracy was confirmed by analyzing of the followings certified reference materials: NIST SRM 1515 Apple leaves and GBW 07603 Aquatic and Terrestrial Biological Products. The developed method was successfully applied for the determination of copper and nickel in real samples including human hair, chicken meat, black tea and canned fish

  12. A preconcentration system for determination of copper and nickel in water and food samples employing flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Tuzen, Mustafa [Department of Chemistry, Gaziosmanpasa University, 60250 Tokat (Turkey); Soylak, Mustafa [Department of Chemistry, Erciyes University, 38039 Kayseri (Turkey)], E-mail: soylak@erciyes.edu.tr; Citak, Demirhan [Department of Chemistry, Gaziosmanpasa University, 60250 Tokat (Turkey); Ferreira, Hadla S.; Korn, Maria G.A. [Universidade Federal da Bahia, Instituto de Quimica, 40170-290 Salvador (Brazil); Bezerra, Marcos A. [Universidade Estadual do Sudoeste da Bahia, 45200-190 Jequie (Brazil)

    2009-03-15

    A separation/preconcentration procedure using solid phase extraction has been proposed for the flame atomic absorption spectrometric determination of copper and nickel at trace level in food samples. The solid phase is Dowex Optipore SD-2 resin contained on a minicolumn, where analyte ions are sorbed as 5-methyl-4-(2-thiazolylazo) resorcinol chelates. After elution using 1 mol L{sup -1} nitric acid solution, the analytes are determinate employing flame atomic absorption spectrometry. The optimization step was performed using a full two-level factorial design and the variables studied were: pH, reagent concentration (RC) and amount of resin on the column (AR). Under the experimental conditions established in the optimization step, the procedure allows the determination of copper and nickel with limit of detection of 1.03 and 1.90 {mu}g L{sup -1}, respectively and precision of 7 and 8%, for concentrations of copper and nickel of 200 {mu}g L{sup -1}. The effect of matrix ions was also evaluated. The accuracy was confirmed by analyzing of the followings certified reference materials: NIST SRM 1515 Apple leaves and GBW 07603 Aquatic and Terrestrial Biological Products. The developed method was successfully applied for the determination of copper and nickel in real samples including human hair, chicken meat, black tea and canned fish.

  13. Determination of anatomic landmarks for optimal placement in captive-bolt euthanasia of goats.

    Science.gov (United States)

    Plummer, Paul J; Shearer, Jan K; Kleinhenz, Katie E; Shearer, Leslie C

    2018-03-01

    OBJECTIVE To determine the optimal anatomic site and directional aim of a penetrating captive bolt (PCB) for euthanasia of goats. SAMPLE 8 skulls from horned and polled goat cadavers and 10 anesthetized horned and polled goats scheduled to be euthanized at the end of a teaching laboratory. PROCEDURES Sagittal sections of cadaver skulls from 8 horned and polled goats were used to determine the ideal anatomic site and aiming of a PCB to maximize damage to the midbrain region of the brainstem for euthanasia. Anatomic sites for ideal placement and directional aiming were confirmed by use of 10 anesthetized horned and polled goats. RESULTS Clinical observation and postmortem examination of the sagittal sections of skulls from the 10 anesthetized goats that were euthanized confirmed that perpendicular placement and firing of a PCB at the intersection of 2 lines, each drawn from the lateral canthus of 1 eye to the middle of the base of the opposite ear, resulted in consistent disruption of the midbrain and thalamus in all goats. Immediate cessation of breathing, followed by a loss of heartbeat in all 10 of the anesthetized goats, confirmed that use of this site consistently resulted in effective euthanasia. CONCLUSIONS AND CLINICAL RELEVANCE Damage to the brainstem and key adjacent structures may be accomplished by firing a PCB perpendicular to the skull over the anatomic site identified at the intersection of 2 lines, each drawn from the lateral canthus of 1 eye to the middle of the base of the opposite ear.

  14. Direct sample introduction-gas chromatography-mass spectrometry for the determination of haloanisole compounds in cork stoppers.

    Science.gov (United States)

    Cacho, J I; Nicolás, J; Viñas, P; Campillo, N; Hernández-Córdoba, M

    2016-12-02

    A solventless analytical method is proposed for analyzing the compounds responsible for cork taint in cork stoppers. Direct sample introduction (DSI) is evaluated as a sample introduction system for the gas chromatography-mass spectrometry (GC-MS) determination of four haloanisoles (HAs) in cork samples. Several parameters affecting the DSI step, including desorption temperature and time, gas flow rate and other focusing parameters, were optimized using univariate and multivariate approaches. The proposed method shows high sensitivity and minimises sample handling, with detection limits of 1.6-2.6ngg -1 , depending on the compound. The suitability of the optimized procedure as a screening method was evaluated by obtaining decision limits (CCα) and detection capabilities (CCβ) for each analyte, which were found to be in 6.9-11.8 and 8.7-14.8ngg -1 , respectively, depending on the compound. Twenty-four cork samples were analysed, and 2,4,6-trichloroanisole was found in four of them at levels between 12.6 and 53ngg -1 . Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Determination of cadmium and lead in urine samples after dispersive solid–liquid extraction on multiwalled carbon nanotubes by slurry sampling electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez Méndez, J.; Barciela García, J.; García Martín, S.; Peña Crecente, R.M.; Herrero Latorre, C., E-mail: carlos.herrero@usc.es

    2015-04-01

    A new method for the determination of Cd and Pb in urine samples has been developed. The method involves dispersive solid-phase extraction (DSPE), slurry sampling (SS), and subsequent electrothermal atomic absorption spectrometry (ETAAS). Oxidized multiwalled carbon nanotubes (MWCNTs) were used as the sorbent material. The isolated MWCNT/analyte aggregates were treated with nitric acid to form a slurry and both metals were determined directly by injecting the slurry into the ETAAS-atomizer. The parameters that influence the adsorption of the metals on MWCNTs in the DSPE process, the formation and extraction of the slurry, and the ETAAS conditions were studied by different factorial design strategies. The detection and quantification limits obtained for Cd under optimized conditions were 9.7 and 32.3 ng L{sup −1}, respectively, and for Pb these limits were 0.13 and 0.43 μg L{sup −1}. The preconcentration factors achieved were 3.9 and 5.4. The RSD values (n = 10) were less than 4.1% and 5.9% for Cd and Pb, respectively. The accuracy of the method was assessed in recovery studies, with values in the range 96–102% obtained for Cd and 97–101% for Pb. In addition, the analysis of certified reference materials gave consistent results. The DSPE–SS–ETAAS method is a novel and useful strategy for the determination of Pb and Cd at low levels in human urine samples. The method is sensitive, fast, and free of matrix interferences, and it avoids the tedious and time-consuming on-column adsorption and elution steps associated with commonly used SPE procedures. The proposed method was used to determine Cd and Pb in urine samples of unexposed healthy people and satisfactory results were obtained. - Highlights: • Cd and Pb determination based on the combination of DSP, SS and ETAAS • Urine matrix was eliminated using DSPE based on multiwalled carbon nanotubes. • Slurry sampling technique permitted the direct injection of sample into the ETAAS atomizer.

  16. Iron status and its determinants in a nationally representative sample of pregnant women.

    Science.gov (United States)

    Vandevijvere, Stefanie; Amsalkhir, Sihame; Van Oyen, Herman; Egli, Ines; Ines, Egli; Moreno-Reyes, Rodrigo

    2013-05-01

    Iron-deficiency anemia is associated with adverse neonatal health outcomes. Iron status and its determinants were assessed in a representative sample of Belgian pregnant women. Blood samples were collected and a questionnaire was completed face-to-face. Hemoglobin (Hb) and mean cell volume were measured using a Beckman Coulter Hematology Analyzer and serum ferritin (SF) and transferrin receptor (sTfr) concentrations by immunoassay. In total, 55 obstetric clinics and 1,311 pregnant women were included. Approximately 40% of third-trimester and 6% of first-trimester women had SF levels less than 15 μg/L. Approximately 21% of third-trimester and 4% of first-trimester women had anemia (Hb 8.5 mg/L). The median body iron stores were 8.1 mg/kg among first-trimester women, but only 3.6 mg/kg among third-trimester women. SF levels were significantly positively associated with age and education level, and were higher among nulliparous women and lower among North-African women. sTfr concentrations were significantly negatively associated with age and were lower among smokers, nulliparous women, and women who planned their pregnancy. Despite the fact that two thirds of Belgian pregnant women took iron-containing supplements, iron deficiency and iron-deficiency anemia were frequent in third-trimester women. The World Health Organization regards this as a moderate public health problem. National iron supplementation guidelines are needed in Belgium to optimize iron status during pregnancy. Copyright © 2013 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

  17. Specific determination of clinical and toxicological important substances in biological samples by LC-MS

    International Nuclear Information System (INIS)

    Mitulovic, G.

    2001-02-01

    This thesis of this dissertation is the specific determination of clinical and toxicological important substances in biological samples by LC-MS. Nicotine was determined in serum after application of nicotine plaster and nicotine nasal spray with HPLC-ESI-MS. Cotinine was determined direct in urine with HPLC-ESI-MS. Short time anesthetics were determined in blood and cytostatics were determined in liquor with HPLC-ESI-MS. (botek)

  18. Spectrophotometric determination of fluoxetine by molecularly imprinted polypyrrole and optimization by experimental design, artificial neural network and genetic algorithm

    Science.gov (United States)

    Nezhadali, Azizollah; Motlagh, Maryam Omidvar; Sadeghzadeh, Samira

    2018-02-01

    A selective method based on molecularly imprinted polymer (MIP) solid-phase extraction (SPE) using UV-Vis spectrophotometry as a detection technique was developed for the determination of fluoxetine (FLU) in pharmaceutical and human serum samples. The MIPs were synthesized using pyrrole as a functional monomer in the presence of FLU as a template molecule. The factors that affecting the preparation and extraction ability of MIP such as amount of sorbent, initiator concentration, the amount of monomer to template ratio, uptake shaking rate, uptake time, washing buffer pH, take shaking rate, Taking time and polymerization time were considered for optimization. First a Plackett-Burman design (PBD) consists of 12 randomized runs were applied to determine the influence of each factor. The other optimization processes were performed using central composite design (CCD), artificial neural network (ANN) and genetic algorithm (GA). At optimal condition the calibration curve showed linearity over a concentration range of 10- 7-10- 8 M with a correlation coefficient (R2) of 0.9970. The limit of detection (LOD) for FLU was obtained 6.56 × 10- 9 M. The repeatability of the method was obtained 1.61%. The synthesized MIP sorbent showed a good selectivity and sensitivity toward FLU. The MIP/SPE method was used for the determination of FLU in pharmaceutical, serum and plasma samples, successfully.

  19. Spectrophotometric determination of fluoxetine by molecularly imprinted polypyrrole and optimization by experimental design, artificial neural network and genetic algorithm.

    Science.gov (United States)

    Nezhadali, Azizollah; Motlagh, Maryam Omidvar; Sadeghzadeh, Samira

    2018-02-05

    A selective method based on molecularly imprinted polymer (MIP) solid-phase extraction (SPE) using UV-Vis spectrophotometry as a detection technique was developed for the determination of fluoxetine (FLU) in pharmaceutical and human serum samples. The MIPs were synthesized using pyrrole as a functional monomer in the presence of FLU as a template molecule. The factors that affecting the preparation and extraction ability of MIP such as amount of sorbent, initiator concentration, the amount of monomer to template ratio, uptake shaking rate, uptake time, washing buffer pH, take shaking rate, Taking time and polymerization time were considered for optimization. First a Plackett-Burman design (PBD) consists of 12 randomized runs were applied to determine the influence of each factor. The other optimization processes were performed using central composite design (CCD), artificial neural network (ANN) and genetic algorithm (GA). At optimal condition the calibration curve showed linearity over a concentration range of 10 -7 -10 -8 M with a correlation coefficient (R 2 ) of 0.9970. The limit of detection (LOD) for FLU was obtained 6.56×10 -9 M. The repeatability of the method was obtained 1.61%. The synthesized MIP sorbent showed a good selectivity and sensitivity toward FLU. The MIP/SPE method was used for the determination of FLU in pharmaceutical, serum and plasma samples, successfully. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Optimization of photometric determination of U with arsenazo III for direct determination of U in steels, soils and waters

    International Nuclear Information System (INIS)

    Kosturiak, A.; Talanova, A.; Rurikova, D.; Kalavska, D.

    1984-01-01

    Conditions were optimized for the reaction of U(VI) with arsenazo III. Recommended as the optimal medium for photometric determination of uranium in the concentration range 0.5 to 50 μg U/ml was the glycine buffer with pH 1.2 to 2.2. The results of the suggested method have better reproducibility than those of the mineral acid procedure used so far. Complexone III should be added to mask the other cations accompanying uranium in steels, waters and rocks. (author)

  1. Preconcentration of Arsenic in Water Samples Using the Composition-Induced Phase Separation Method and Determination by ETAAS

    Directory of Open Access Journals (Sweden)

    Güçoğlu M.

    2013-04-01

    Full Text Available A new phase transition microextraction method was developed for determination of trace amount of arsenic ions in water samples in this work. The method is based on the critical point of miscibility of solvents. In this method the mixed solution of sample and organic solvent is initially homogeneous but is separated into two phases by adding a secondary solvent (modifier. In acidic medium As(V was complexed with ammonium molybdate, this complex was quantitatively extracted to the mixture of organic solvent (acetonitrile/methyl isobutyl ketone before ETAAS determination. Total inorganic arsenic (III, V was extracted similarly after oxidation of As(III to As(V with nitric acid. Concentration of As(III was calculated by difference in the concentration between total arsenic and As(V. Optimization of the experimental conditions and instrumental parameters was investigated in detail. A detection limit of 0.05 μgL−1 with enrichment factor of 85 was achieved for only 5 mL of sample. The analytical curve was linear in the concentration range of 0.25-4.00 μgL−1. Relative standard deviation (RSD for 10 replicate determinations of 2.0 μgL−1 of As(V was 4,1%. The method was successfully applied to preconcentration and determination of arsenic in real water samples.

  2. Optimizing sampling strategy for radiocarbon dating of Holocene fluvial systems in a vertically aggrading setting

    International Nuclear Information System (INIS)

    Toernqvist, T.E.; Dijk, G.J. Van

    1993-01-01

    The authors address the question of how to determine the period of activity (sedimentation) of fossil (Holocene) fluvial systems in vertically aggrading environments. The available data base consists of almost 100 14 C ages from the Rhine-Meuse delta. Radiocarbon samples from the tops of lithostratigraphically correlative organic beds underneath overbank deposits (sample type 1) yield consistent ages, indicating a synchronous onset of overbank deposition over distances of at least up to 20 km along channel belts. Similarly, 14 C ages from the base of organic residual channel fills (sample type 3) generally indicate a clear termination of within-channel sedimentation. In contrast, 14 C ages from the base of organic beds overlying overbank deposits (sample type 2), commonly assumed to represent the end of fluvial sedimentation, show a large scatter reaching up to 1000 14 C years. It is concluded that a combination of sample types 1 and 3 generally yields a satisfactory delimitation of the period of activity of a fossil fluvial system. 30 refs., 11 figs., 4 tabs

  3. Development and Validation of Chronopotentiometric Method for Imidacloprid Determination in Pesticide Formulations and River Water Samples

    Directory of Open Access Journals (Sweden)

    Ana Đurović

    2016-01-01

    Full Text Available A new electrochemical method for determination of imidacloprid using chronopotentiometry on thin film mercury and glassy carbon electrode was presented. The most important experimental parameters of chronopotentiometry were examined and optimized with respect to imidacloprid analytical signal. Imidacloprid provided well-defined reduction peak in Britton-Robinson buffer on thin film mercury electrode at −1.0 V (versus Ag/AgCl (KCl, 3.5 mol/L and on glassy carbon electrode at −1.2 V (versus Ag/AgCl (KCl, 3.5 mol/L. The reduction time was linearly proportional to concentrations from 0.8 to 30.0 mg/L on thin film mercury electrode and from 7.0 to 70.0 mg/L on glassy carbon electrode. The detection limits were 0.17 mg/L and 0.93 mg/L for thin film mercury and glassy carbon electrode, respectively. The estimation of method precision as a function of repeatability and reproducibility showed relative standard deviations values lower than 3.73%. Recovery values from 97.3 to 98.1% confirmed the accuracy of the proposed method, while the constancy of the transition time with deliberated small changes in the experimental parameters indicated a very good robustness. A minor influence of possible interfering compounds proved good selectivity of the method. Developed method was applied for imidacloprid determination in commercial pesticide formulations and river water samples.

  4. Determination of trace inorganic mercury species in water samples by cloud point extraction and UV-vis spectrophotometry.

    Science.gov (United States)

    Ulusoy, Halil Ibrahim

    2014-01-01

    A new micelle-mediated extraction method was developed for preconcentration of ultratrace Hg(II) ions prior to spectrophotometric determination. 2-(2'-Thiazolylazo)-p-cresol (TAC) and Ponpe 7.5 were used as the chelating agent and nonionic surfactant, respectively. Hg(II) ions form a hydrophobic complex with TAC in a micelle medium. The main factors affecting cloud point extraction efficiency, such as pH of the medium, concentrations of TAC and Ponpe 7.5, and equilibration temperature and time, were investigated in detail. An overall preconcentration factor of 33.3 was obtained upon preconcentration of a 50 mL sample. The LOD obtained under the optimal conditions was 0.86 microg/L, and the RSD for five replicate measurements of 100 microg/L Hg(II) was 3.12%. The method was successfully applied to the determination of Hg in environmental water samples.

  5. Determination of trace amount of lead in industrial and municipal effluent water samples based on dispersive liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Shirkhanloo, H. [Iranian Petroleum Industry Health Research Institute, Occupational and Environmental Health Research Center, Tehran (Iran, Islamic Republic of); Sedighi, K.; Mousavi, H. Z., E-mail: hzmousavi@semnan.ac.ir [Semnan University, College of Science, Department of Chemistry, Semnan (Iran, Islamic Republic of)

    2014-10-01

    In this study, a simple, sensitive and accurate method was developed for the determination of lead ion by combining ionic liquid dispersive liquid-liquid extraction (Il-DLL E) with flame atomic absorption spectrometry. Tetraethyl thiuram disulfide (Tetd), acetone and 1-octyl-3m ethylimidazolium hexafluorophosphate [(C{sub 8}MIM) (PF{sub 6})] were used as the chelating agent, dispersive and extraction solvent, respectively. Under the optimal conditions, the calibration graph was linear in the range of 5-190 μg L{sup -1} of lead and the detection limit was 0.8 μg L{sup -1} with a sample volume of 200 ml. The proposed method was validated by the analysis of one certified reference material and applied successfully to the determination of lead in real water samples. (Author)

  6. Determination of γ-hydroxybutyrate in human urine samples by ion exclusion and ion exchange two-dimensional chromatography system.

    Science.gov (United States)

    Liu, Junwei; Deng, Zhifen; Zhu, Zuoyi; Wang, Yong; Wang, Guoqing; Sun, Yu-An; Zhu, Yan

    2017-12-15

    A two-dimensional ion chromatography system was developed for the determination of γ-hydroxybutyrate (GHB) in human urine samples. Ion exclusion chromatography was used in the first dimensional separation for elimination of urine matrices and detection of GHB above 10mgL -1 , ion exchange chromatography was used in the second dimensional separation via column-switching technique for detection of GHB above 0.08mgL -1 . Under the optimized chromatographic conditions, the ion exclusion and ion exchange chromatography separation system exhibited satisfactory repeatability (RSDchromatography system was convenient and practical for the determination of GHB in human urine samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Liquid-liquid extraction assisted by a carbon nanoparticles interface. Electrophoretic determination of atrazine in environmental samples.

    Science.gov (United States)

    Caballero-Díaz, Encarnación; Simonet, Bartolomé; Valcárcel, Miguel

    2013-10-21

    A novel method for the determination of atrazine, using liquid-liquid extraction assisted by a nanoparticles film formed in situ and composed of organic solvent stabilized-carbon nanoparticles, is described. The presence of nanoparticles located at the liquid-liquid interface reinforced the extraction of analyte from matrix prior to capillary electrophoresis (CE) analysis. Some influential experimental variables were optimized in order to enhance the extraction efficiency. The developed procedure confirmed that carbon nanoparticles, especially multi-walled carbon nanotubes, are suitable to be used in sample treatment processes introducing new mechanisms of interaction with the analyte. The application of the proposed preconcentration method followed by CE detection enabled the determination of atrazine in spiked river water providing acceptable RSD values (11.6%) and good recoveries (about 87.0-92.0%). Additionally, a similar extraction scheme was tested in soil matrices with a view to further applications in real soil samples.

  8. Determination of trace amount of lead in industrial and municipal effluent water samples based on dispersive liquid-liquid extraction

    International Nuclear Information System (INIS)

    Shirkhanloo, H.; Sedighi, K.; Mousavi, H. Z.

    2014-01-01

    In this study, a simple, sensitive and accurate method was developed for the determination of lead ion by combining ionic liquid dispersive liquid-liquid extraction (Il-DLL E) with flame atomic absorption spectrometry. Tetraethyl thiuram disulfide (Tetd), acetone and 1-octyl-3m ethylimidazolium hexafluorophosphate [(C 8 MIM) (PF 6 )] were used as the chelating agent, dispersive and extraction solvent, respectively. Under the optimal conditions, the calibration graph was linear in the range of 5-190 μg L -1 of lead and the detection limit was 0.8 μg L -1 with a sample volume of 200 ml. The proposed method was validated by the analysis of one certified reference material and applied successfully to the determination of lead in real water samples. (Author)

  9. 90Sr and 137Cs determination in milk and foodstuff samples in North and Middle Moravia

    International Nuclear Information System (INIS)

    Bartuskova, M.; Lusnak, J.; Rada, J.; Beckova, V.

    2008-01-01

    Activities of radionuclides Sr-90 and Cs-137 in milk and parts of foodstuff have been determined in National Radiation Protection Institute for many years. Sr-90 activity in those samples determinate branch Ostrava by radiochemical procedure - precipitation with oxalic acid and measuring with using gas-flow proportional detector. Gamma spectrometry with HPGe detector is using for 137 Cs determination. (authors)

  10. Single injection 51Cr EDTA plasma clearance determination in children using capillary blood samples

    International Nuclear Information System (INIS)

    Broechner-Mortensen, J.; Christoffersen, J.

    1977-01-01

    The reliability of a determination of the total 51 Cr EDTA plasma clearance (e) (and with it the glomerular filtration rate), by a simplified single injection method (injected dose: 4.5 μCi per kg b.w.) using capillary blood samples (0.2 ml), was investigated in twenty children. Clearance values determined from capillary blood samples did not differ significantly from those measured simultaneously from venous blood samples, the mean ratio+-SD being 1.02+-0.06(n = 10). The reproducibility (total day-to-day variation) of E determined from capillary blood samples was 6.7% in children with decreased renal function (n = 3) and 6.9% in children with normal renal function (n = 7). The present data indicate that the use of capillary blood samples is an accurate and very precise approach for determination of E in children. (Auth.)

  11. Online Determination of Sm, Eu and Yb in Environmental Samples by Inductively Coupled Plasma – Optical Emission Spectrometry

    Directory of Open Access Journals (Sweden)

    J. Dilip Kumar

    2007-01-01

    Full Text Available A procedure was developed for the determination of Sm, Eu and Yb in water samples by inductively coupled plasma-optical emission spectrometry (ICP-OES after preconcentration on synthesized 5-(4-pyridyl azo-8-quinolinol supported by Borassus flabellifer inflorescence (BFI. The sorbed element was subsequently eluted with 0.4 M HNO3 and the acid eluates were analyzed by ICP-OES. Under the optimal conditions, Sm, Eu and Yb in aqueous samples were concentrated 100-fold. Recoveries were obtained by the proposed method in the range of 98.6 -99.8%. This method was also applied for the analysis of spiked and natural water samples. The results provide strong evidence to support the hypothesis of an adsorption mechanism.

  12. Laser fluorimetric determination of uranium in environmental samples from Nile Delta and adjacent regions

    International Nuclear Information System (INIS)

    Shawky, S.; Ibrahiem, N.; Farouk, A.; Ghods, A.

    1994-01-01

    Total uranium content was determined in soil and plant samples obtained from various areas in the Nile Delta. Samples taken from east and west of the delta, Suez canal cities and from the Alexandria region were analysed using laser fluorimetry (LF). Uranium was extracted from digested samples with methyl-isobutyl ketone and measured using a laser fluorimeter. The radium content of the same soil samples was determined using gamma spectroscopy. The uranium content of plant samples was determined using LF, since this technique has a detection limit lower than that of GS. Uranium content in the samples varied between 0.6-4.4 μg/g for soil and 0.032-0.17 μg/g for plant tissue. (author)

  13. Rapid determination of 226Ra in drinking water samples using dispersive liquid-liquid microextraction coupled with liquid scintillation counting

    International Nuclear Information System (INIS)

    Sadi, B.K.; Chunsheng Li; Kramer, G.H.; Johnson, C.L.; Queenie Ko; Lai, E.P.C.

    2011-01-01

    A new radioanalytical method was developed for rapid determination of 226 Ra in drinking water samples. The method is based on extraction and preconcentration of 226 Ra from a water sample to an organic solvent using a dispersive liquid-liquid microextraction (DLLME) technique followed by radiometric measurement using liquid scintillation counting. In DLLME for 226 Ra, a mixture of an organic extractant (toluene doped with dibenzo-21-crown-7 and 2-theonyltrifluoroacetone) and a disperser solvent (acetonitrile) is rapidly injected into the water sample resulting in the formation of an emulsion. Within the emulsion, 226 Ra reacts with dibenzo-21-crown-7 and 2-theonyltrifluoroacetone and partitions into the fine droplets of toluene. The water/toluene phases were separated by addition of acetonitrile as a de-emulsifier solvent. The toluene phase containing 226 Ra was then measured by liquid scintillation counting. Several parameters were studied to optimize the extraction efficiency of 226 Ra, including water immiscible organic solvent, disperser and de-emulsifier solvent type and their volume, chelating ligands for 226 Ra and their concentrations, inorganic salt additive and its concentration, and equilibrium pH. With the optimized DLLME conditions, the accuracy (expressed as relative bias, B r ) and method repeatability (expressed as relative precision, S B ) were determined by spiking 226 Ra at the maximum acceptable concentration level (0.5 Bq L -1 ) according to the Guidelines for Canadian Drinking Water Quality. Accuracy and repeatability were found to be less than -5% (B r ) and less than 6% (S B ), respectively, for both tap water and bottled natural spring water samples. The minimum detectable activity and sample turnaround time for determination of 226 Ra was 33 mBq L -1 and less than 3 h, respectively. The DLLME technique is selective for extraction of 226 Ra from its decay progenies. (author)

  14. Matrix-assisted laser desorption/ionization sample preparation optimization for structural characterization of poly(styrene-co-pentafluorostyrene) copolymers.

    Science.gov (United States)

    Tisdale, Evgenia; Kennedy, Devin; Xu, Xiaodong; Wilkins, Charles

    2014-01-15

    The influence of the sample preparation parameters (the choice of the matrix, matrix:analyte ratio, salt:analyte ratio) was investigated and optimal conditions were established for the MALDI time-of-flight mass spectrometry analysis of the poly(styrene-co-pentafluorostyrene) copolymers. These were synthesized by atom transfer radical polymerization. Use of 2,5-dihydroxybenzoic acid as matrix resulted in spectra with consistently high ion yields for all matrix:analyte:salt ratios tested. The optimized MALDI procedure was successfully applied to the characterization of three copolymers obtained by varying the conditions of polymerization reaction. It was possible to establish the nature of the end groups, calculate molecular weight distributions, and determine the individual length distributions for styrene and pentafluorostyrene monomers, contained in the resulting copolymers. Based on the data obtained, it was concluded that individual styrene chain length distributions are more sensitive to the change in the composition of the catalyst (the addition of small amount of CuBr2) than is the pentafluorostyrene component distribution. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Human error considerations and annunciator effects in determining optimal test intervals for periodically inspected standby systems

    International Nuclear Information System (INIS)

    McWilliams, T.P.; Martz, H.F.

    1981-01-01

    This paper incorporates the effects of four types of human error in a model for determining the optimal time between periodic inspections which maximizes the steady state availability for standby safety systems. Such safety systems are characteristic of nuclear power plant operations. The system is modeled by means of an infinite state-space Markov chain. Purpose of the paper is to demonstrate techniques for computing steady-state availability A and the optimal periodic inspection interval tau* for the system. The model can be used to investigate the effects of human error probabilities on optimal availability, study the benefits of annunciating the standby-system, and to determine optimal inspection intervals. Several examples which are representative of nuclear power plant applications are presented

  16. Preparation of /sup 237/Np samples by electrodeposition and its determination by alpha spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Mertzig, W; Matsuda, H T; Araujo, B.F. de; Araujo, J.A. de [Instituto de Pesquisas Energeticas e Nucleares, Sao Paulo (Brazil). Centro de Engenharia Quimica

    1980-01-01

    An analytical method followed by alpha spectrometry was developed for the determination of trace amounts of actinides. A technique for quantitative electrodeposition of /sup 237/Np, under optimal conditions, using a carrier, is presented. This method will be applied for the control of trace amounts of /sup 237/Np in the solutions from the reprocessing (Purex process) of irradiated uranium.

  17. An overview of sample preparation procedures for LC-MS multiclass antibiotic determination in environmental and food samples.

    Science.gov (United States)

    Moreno-Bondi, María Cruz; Marazuela, María Dolores; Herranz, Sonia; Rodriguez, Erika

    2009-10-01

    Antibiotics are a class of pharmaceuticals that are of great interest due to the large volumes of these substances that are consumed in both human and veterinary medicine, and due to their status as the agents responsible for bacterial resistance. They can be present in foodstuffs and in environmental samples as multicomponent chemical mixtures that exhibit a wide range of mechanisms of action. Moreover, they can be transformed into different metabolites by the action of microorganisms, as well as by other physical or chemical means, resulting in mixtures with higher ecotoxicities and risks to human health than those of the individual compounds. Therefore, there is growing interest in the availability of multiclass methods for the analysis of antimicrobial mixtures in environmental and food samples at very low concentrations. Liquid chromatography (LC) has become the technique of choice for multiclass analysis, especially when coupled to mass spectrometry (LC-MS) and tandem MS (LC-MS(2)). However, due to the complexity of the matrix, in most cases an extraction step for sample clean-up and preconcentration is required before analysis in order to achieve the required sensitivities. This paper reviews the most recent developments and applications of multiclass antimicrobial determination in environmental and food matrices, emphasizing the practical aspects of sample preparation for the simultaneous extraction of antimicrobials from the selected samples. Future trends in the application of LC-MS-based techniques to multiclass antibiotic analysis are also presented.

  18. Two media method for linear attenuation coefficient determination of irregular soil samples

    International Nuclear Information System (INIS)

    Vici, Carlos Henrique Georges

    2004-01-01

    In several situations of nuclear applications, the knowledge of gamma-ray linear attenuation coefficient for irregular samples is necessary, such as in soil physics and geology. This work presents the validation of a methodology for the determination of the linear attenuation coefficient (μ) of irregular shape samples, in such a way that it is not necessary to know the thickness of the considered sample. With this methodology irregular soil samples (undeformed field samples) from Londrina region, north of Parana were studied. It was employed the two media method for the μ determination. It consists of the μ determination through the measurement of a gamma-ray beam attenuation by the sample sequentially immersed in two different media, with known and appropriately chosen attenuation coefficients. For comparison, the theoretical value of μ was calculated by the product of the mass attenuation coefficient, obtained by the WinXcom code, and the measured value of the density sample. This software employs the chemical composition of the samples and supplies a table of the mass attenuation coefficients versus the photon energy. To verify the validity of the two media method, compared with the simple gamma ray transmission method, regular pome stone samples were used. With these results for the attenuation coefficients and their respective deviations, it was possible to compare the two methods. In this way we concluded that the two media method is a good tool for the determination of the linear attenuation coefficient of irregular materials, particularly in the study of soils samples. (author)

  19. Multivariate optimization of headspace trap for furan and furfural simultaneous determination in sponge cake.

    Science.gov (United States)

    Cepeda-Vázquez, Mayela; Blumenthal, David; Camel, Valérie; Rega, Barbara

    2017-03-01

    Furan, a possibly carcinogenic compound to humans, and furfural, a naturally occurring volatile contributing to aroma, can be both found in thermally treated foods. These process-induced compounds, formed by close reaction pathways, play an important role as markers of food safety and quality. A method capable of simultaneously quantifying both molecules is thus highly relevant for developing mitigation strategies and preserving the sensory properties of food at the same time. We have developed a unique reliable and sensitive headspace trap (HS trap) extraction method coupled to GC-MS for the simultaneous quantification of furan and furfural in a solid processed food (sponge cake). HS Trap extraction has been optimized using an optimal design of experiments (O-DOE) approach, considering four instrumental and two sample preparation variables, as well as a blocking factor identified during preliminary assays. Multicriteria and multiple response optimization was performed based on a desirability function, yielding the following conditions: thermostatting temperature, 65°C; thermostatting time, 15min; number of pressurization cycles, 4; dry purge time, 0.9min; water / sample amount ratio (dry basis), 16; and total amount (water + sample amount, dry basis), 10g. The performances of the optimized method were also assessed: repeatability (RSD: ≤3.3% for furan and ≤2.6% for furfural), intermediate precision (RSD: 4.0% for furan and 4.3% for furfural), linearity (R 2 : 0.9957 for furan and 0.9996 for furfural), LOD (0.50ng furan g sample dry basis -1 and 10.2ng furfural g sample dry basis -1 ), LOQ (0.99ng furan g sample dry basis -1 and 41.1ng furfural g sample dry basis -1 ). Matrix effect was observed mainly for furan. Finally, the optimized method was applied to other sponge cakes with different matrix characteristics and levels of analytes. Copyright © 2016. Published by Elsevier B.V.

  20. OPTIMIZING CONDITIONS FOR SPECTROPHOTOMETRIC DETERMINATION OF TOTAL POLYPHENOLS IN WINES USING FOLIN-CIOCALTEU REAGENT

    Directory of Open Access Journals (Sweden)

    Daniel Bajčan

    2013-02-01

    Full Text Available Wine is a complex beverage that obtains its properties mainly due to synergistic effect of alcohol, organic acids, arbohydrates, as well as the phenolic and aromatic substances. At present days, we can observe an increased interest in the study of polyphenols in wines that have antioxidant, antimicrobial, anti-inflammatory, anti-cancer and many other beneficial effects. Moderate and regular consumption of the red wine especially, with a high content of phenolic compounds, has a beneficial effect on human health. The aim of this work was to optimize conditions for spectrophotometric determination of total polyphenols in winwas to optimize conditions for spectrophotometric determination of total polyphenols in winwas to optimize conditions for spectrophotometric determination of total polyphenols in winwas to optimize conditions for pectrophotometric determination of total polyphenols in wine using Folin-Ciocaulteu reagent. Based on several studies, in order to minimize chemical use and optimize analysis time, we have proposed a method for the determination of total polyphenols using 0.25 ml Folin-Ciocaulteu reagent, 3 ml of 20% Na2CO3 solution and time of coloring complex 1.5 hour. We f

  1. Stir-bar supported micro-solid-phase extraction for the determination of polychlorinated biphenyl congeners in serum samples.

    Science.gov (United States)

    Sajid, Muhammad; Basheer, Chanbasha

    2016-07-15

    In present work, a new configuration of micro-solid phase extraction was introduced and termed as stir-bar supported micro-solid-phase extraction (SB-μ-SPE). A tiny stir-bar was packed inside the porous polypropylene membrane along with sorbent material and the edges of membrane sheet were heat sealed to secure the contents. The packing of stir-bar inside the μ-SPE device does not allow the device to stick with the wall or any corner of the sample vial during extraction, which is, however, a frequent observation in routine μ-SPE. Moreover, it enhances effective surface area of the sorbent exposed to sample solution through continuous agitation (motion and rotation). It also completely immerses the SB-μ-SPE device in the sample solution even for non-polar sorbents. Polychlorinated biphenyls (PCBs) were selected as model compounds and the method performance was evaluated in human serum samples. After extraction, samples were analyzed by gas chromatography mass spectrometry (GC-MS). The factors that affect extraction efficiency of SB-μ-SPE were optimized. Under optimum conditions, a good linearity (0.1-100ngmL(-1)) with coefficients of determinations ranging from 0.9868 to 0.9992 was obtained. Limits of detections were ranged between 0.003 and 0.047ngmL(-1). Acceptable values for inter-day (3.2-9.1%) and intra-day (3.1-7.2%) relative standard deviations were obtained. The optimized method was successfully applied to determine the concentration of PCB congeners in human serum samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Determination of U and Th α-emitters in NORM samples through extraction chromatography by using new and recycled UTEVA resins

    International Nuclear Information System (INIS)

    Casacuberta, N.; Lehritani, M.; Mantero, J.; Masqué, P.; Garcia-Orellana, J.; Garcia-Tenorio, R.

    2012-01-01

    This manuscript describes a protocol for the determination of U and Th isotopes via alpha spectrometry in NORM samples containing high concentrations of these radionuclides, up to kBq kg −1 . This technique is based on extraction chromatography with UTEVA (Triskem Int.) resins and it has been tested using both NORM samples from a phosphate industry and reference materials. The results proved that this method is highly optimized in terms of accuracy and precision when dealing with NORM samples. Recycling of UTEVA columns was also checked using NORM samples and successful results were obtained for both U and Th isotopes, thus proving the feasibility of re-using these type of columns. - Highlights: ► U and Th isotopes in NORM samples are determined via alpha spectrometry. ► The results show a highly optimized data in terms of accuracy and precision. ► Recycling of UTEVA columns was also checked and successful results were obtained.

  3. Amines as extracting agents for the quantitative determinations of actinides in biological samples

    International Nuclear Information System (INIS)

    Singh, N.P.

    1987-01-01

    The use of amines (primary, secondary and tertiary chains and quaternary ammonium salts) as extracting agents for the quantitative determination of actinides in biological samples is reviewed. Among the primary amines, only Primene JM-T is used to determine Pu in urine and bone. No one has investigated the possibility of using secondary amines to quantitatively extract actinides from biological samples. Among the tertiary amines, tri-n-octylamine, tri-iso-octylamine, tyricaprylamine (Alamine) and trilaurylamine (tridodecylamine) are used extensively to extract and separate the actinides from biological samples. Only one quaternary ammonium salt, methyltricapryl ammonium chloride (Aliquat-336), is used to extract Pu from biological samples. (author) 28 refs

  4. Passive Dosing to Determine the Speciation of Hydrophobic Organic Chemicals in Aqueous Samples

    DEFF Research Database (Denmark)

    Birch, Heidi; Gouliarmou, V.; Lützhøft, Hans-Christian Holten

    2010-01-01

    A new analytical approach to determine the speciation of hydrophobic organic analytes is presented. The freely dissolved concentration in a sample is controlled by passive dosing from silicone (poly(dimethylsiloxane)), and the total sample concentration at equilibrium is measured. The free fraction...... is determined as the ratio between measured concentrations in pure water and sample. C-14-labeled fluoranthene served as model analyte, and total sample concentrations were easily measured by liquid scintillation counting. The method was applied to surface water, stormwater runoff, and wastewater...... (SPME). This analytical approach combines simplicity with high precision, and it does not require any phase separation steps....

  5. Optimal moment determination in POME-copula based hydrometeorological dependence modelling

    Science.gov (United States)

    Liu, Dengfeng; Wang, Dong; Singh, Vijay P.; Wang, Yuankun; Wu, Jichun; Wang, Lachun; Zou, Xinqing; Chen, Yuanfang; Chen, Xi

    2017-07-01

    Copula has been commonly applied in multivariate modelling in various fields where marginal distribution inference is a key element. To develop a flexible, unbiased mathematical inference framework in hydrometeorological multivariate applications, the principle of maximum entropy (POME) is being increasingly coupled with copula. However, in previous POME-based studies, determination of optimal moment constraints has generally not been considered. The main contribution of this study is the determination of optimal moments for POME for developing a coupled optimal moment-POME-copula framework to model hydrometeorological multivariate events. In this framework, margins (marginals, or marginal distributions) are derived with the use of POME, subject to optimal moment constraints. Then, various candidate copulas are constructed according to the derived margins, and finally the most probable one is determined, based on goodness-of-fit statistics. This optimal moment-POME-copula framework is applied to model the dependence patterns of three types of hydrometeorological events: (i) single-site streamflow-water level; (ii) multi-site streamflow; and (iii) multi-site precipitation, with data collected from Yichang and Hankou in the Yangtze River basin, China. Results indicate that the optimal-moment POME is more accurate in margin fitting and the corresponding copulas reflect a good statistical performance in correlation simulation. Also, the derived copulas, capturing more patterns which traditional correlation coefficients cannot reflect, provide an efficient way in other applied scenarios concerning hydrometeorological multivariate modelling.

  6. Determination of Iron and Nickel in Geological Samples by Activation Analysis with Reactor Fast Neutrons

    International Nuclear Information System (INIS)

    El Abd, A.

    2009-01-01

    Threshold reactions induced by reactor fast neutrons are well recognized. The concentration of Fe and Ni were determined in nine geological samples by activation analysis with reactor fast neutrons using the threshold reactions 5 4F e( n,p) 54 Mn and 58 Ni ( n, p )'5 8 Co respectively. The fast neutron flux was determined using the reactions 92 Mo(n, 2n) 92 mNb and 95 Mo(n,p) 95 Nb. The determined concentration of Fe and Ni in the samples were checked by determining them in the GSJ JB-1 reference material using the same , ( p, n) reactions. There are a good agreement between the measured and recommended values. The concentrations of Fe were also determined by the ) , ( n, γ) capture reactions in the geological samples and the JB-1 reference material using the K θ - NAA method. There are good agreements between the determined concentrations from the ) , ( p, n) and the ( γ, n) reactions.

  7. DETERMINATION OF BRAKING OPTIMAL MODE OF CONTROLLED CUT OF DESIGN GROUP

    Directory of Open Access Journals (Sweden)

    A. S. Dorosh

    2015-06-01

    Full Text Available Purpose. The application of automation systems of breaking up process on the gravity hump is the efficiency improvement of their operation, absolute provision of trains breaking up safety demands, as well as improvement of hump staff working conditions. One of the main tasks of the indicated systems is the assurance of cuts reliable separation at all elements of their rolling route to the classification track. This task is a sophisticated optimization problem and has not received a final decision. Therefore, the task of determining the cuts braking mode is quite relevant. The purpose of this research is to find the optimal braking mode of control cut of design group. Methodology. In order to achieve the purpose is offered to use the direct search methods in the work, namely the Box complex method. This method does not require smoothness of the objective function, takes into account its limitations and does not require calculation of the function derivatives, and uses only its value. Findings. Using the Box method was developed iterative procedure for determining the control cut optimal braking mode of design group. The procedure maximizes the smallest controlled time interval in the group. To evaluate the effectiveness of designed procedure the series of simulation experiments of determining the control cut braking mode of design group was performed. The results confirmed the efficiency of the developed optimization procedure. Originality. The author formalized the task of optimizing control cut braking mode of design group, taking into account the cuts separation of design group at all elements (switches, retarders during cuts rolling to the classification track. The problem of determining the optimal control cut braking mode of design group was solved. The developed braking mode ensures cuts reliable separation of the group not only at the switches but at the retarders of brake position. Practical value. The developed procedure can be

  8. Optimization and validation of spectrophotometric methods for determination of finasteride in dosage and biological forms

    Science.gov (United States)

    Amin, Alaa S.; Kassem, Mohammed A.

    2012-01-01

    Aim and Background: Three simple, accurate and sensitive spectrophotometric methods for the determination of finasteride in pure, dosage and biological forms, and in the presence of its oxidative degradates were developed. Materials and Methods: These methods are indirect, involve the addition of excess oxidant potassium permanganate for method A; cerric sulfate [Ce(SO4)2] for methods B; and N-bromosuccinimide (NBS) for method C of known concentration in acid medium to finasteride, and the determination of the unreacted oxidant by measurement of the decrease in absorbance of methylene blue for method A, chromotrope 2R for method B, and amaranth for method C at a suitable maximum wavelength, λmax: 663, 528, and 520 nm, for the three methods, respectively. The reaction conditions for each method were optimized. Results: Regression analysis of the Beer plots showed good correlation in the concentration ranges of 0.12–3.84 μg mL–1 for method A, and 0.12–3.28 μg mL–1 for method B and 0.14 – 3.56 μg mL–1 for method C. The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were evaluated. The stoichiometric ratio between the finasteride and the oxidant was estimated. The validity of the proposed methods was tested by analyzing dosage forms and biological samples containing finasteride with relative standard deviation ≤ 0.95. Conclusion: The proposed methods could successfully determine the studied drug with varying excess of its oxidative degradation products, with recovery between 99.0 and 101.4, 99.2 and 101.6, and 99.6 and 101.0% for methods A, B, and C, respectively. PMID:23781478

  9. Determination of total mercury for marine environmental monitoring studies by solid sampling continuum source high resolution atomic absorption spectrometry

    Science.gov (United States)

    Mandjukov, Petko; Orani, Anna Maria; Han, Eunmi; Vassileva, Emilia

    2015-01-01

    The most critical step in almost all commonly used analytical procedures for Hg determination is the sample preparation due to its extreme volatility. One of the possible solutions of this problem is the application of methods for direct analysis of solid samples. The possibilities for solid sampling high resolution continuum source atomic absorption spectrometry (HR CS AAS) determination of total mercury in various marine environmental samples e.g. sediments and biota are object of the present study. The instrumental parameters were optimized in order to obtain reproducible and interference free analytical signal. A calibration technique based on the use of solid standard certified reference materials similar to the nature of the analyzed sample was developed and applied to various CRMs and real samples. This technique allows simple and reliable evaluation of the uncertainty of the result and the metrological characteristics of the method. A validation approach in line with the requirements of ISO 17025 standard and Eurachem guidelines was followed. With this in mind, selectivity, working range (0.06 to 25 ng for biota and 0.025 to 4 ng for sediment samples, expressed as total Hg) linearity (confirmed by Student's t-test), bias (1.6-4.3%), repeatability (4-9%), reproducibility (9-11%), and absolute limit of detection (0.025 ng for sediment, 0.096 ng for marine biota) were systematically assessed using solid CRMs. The relative expanded uncertainty was estimated at 15% for sediment sample and 8.5% for marine biota sample (k = 2). Demonstration of traceability of measurement results is also presented. The potential of the proposed analytical procedure, based on solid sampling HR CS AAS technique was demonstrated by direct analysis of sea sediments form the Caribbean region and various CRMs. Overall, the use of solid sampling HR CS AAS permits obtaining significant advantages for the determination of this complex analyte in marine samples, such as straightforward

  10. Experimental parameters optimization of instrumental neutron activation analysis in order to determine selected elements in some industrial soils in Turkey

    International Nuclear Information System (INIS)

    Haciyakupoglu, Sevilay; Nur Esen, Ayse; Erenturk, Sema

    2014-01-01

    The purpose of this study is optimization of the experimental parameters for analysis of soil matrix by instrumental neutron activation analysis and quantitative determination of barium, cerium, lanthanum, rubidium, scandium and thorium in soil samples collected from industrialized urban areas near Istanbul. Samples were irradiated in TRIGA MARK II Research Reactor of Istanbul Technical University. Two types of reference materials were used to check the accuracy of the applied method. The achieved results were found to be in compliance with certified values of the reference materials. The calculated E n numbers for mentioned elements were found to be less than 1. The presented data of element concentrations in soil samples will help to trace the pollution as an impact of urbanization and industrialization, as well as providing database for future studies. - Highlights: • Optimization of experimental parameters is important for high sensitivity results by INAA. • Assessment of uncertainty sources is necessary to increase reliability of results. • The aim of this study is to determine a number of elements in industrial soil samples. • The higher concentrations of studied elements are due to rapid industrialization. • This baseline data can be used in future studies for other industrial areas

  11. Determination of thiobencarb in water samples by gas chromatography using a homogeneous liquid-liquid microextraction via flotation assistance procedure

    Directory of Open Access Journals (Sweden)

    H.A. Mashayekhi

    2013-09-01

    Full Text Available Homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA coupled with gas chromatography-flame ionization detection (GC-FID was applied for the extraction and determination of thiobencarb in water samples. In this study, a special extraction cell was designed to facilitate collection of the low-density solvent extraction. No centrifugation was required in this procedure. The water sample solution was added into the extraction cell which contained an appropriate mixture of toluene (as an extraction solvent and acetone (as a homogeneous solvent. By using air flotation, the organic solvent was collected at the conical part of the designed cell. The effect of the different parameters on the efficiency of extraction such as type and volume of extraction and homogeneous solvents, ionic strength and extraction time were studied and optimized. Under the optimal conditions, linearity of the method was in the range of 1.0-200 µg L-1. The relative standard deviations in the real samples varied from 7.8-11.7 % (n = 3. The proposed method was successfully applied to analysis of thiobencarb in the water samples and satisfactory results were obtained.DOI: http://dx.doi.org/10.4314/bcse.v27i3.4

  12. High-performance liquid chromatographic determination of histamine in biological samples: the cerebrospinal fluid challenge--a review.

    Science.gov (United States)

    Wang, Zhaopin; Wu, Juanli; Wu, Shihua; Bao, Aimin

    2013-04-24

    Histamine, a neurotransmitter crucially involved in a number of basic physiological functions, undergoes changes in neuropsychiatric disorders. Detection of histamine in biological samples such as cerebrospinal fluid (CSF) is thus of clinical importance. The most commonly used method for measuring histamine levels is high performance liquid chromatography (HPLC). However, factors such as very low levels of histamine, the even lower CSF-histamine and CSF-histamine metabolite levels, especially in certain neuropsychiatric diseases, rapid formation of histamine metabolites, and other confounding elements during sample collection, make analysis of CSF-histamine and CSF-histamine metabolites a challenging task. Nonetheless, this challenge can be met, not only with respect to HPLC separation column, derivative reagent, and detector, but also in terms of optimizing the CSF sample collection. This review aims to provide a general insight into the quantitative analyses of histamine in biological samples, with an emphasis on HPLC instruments, methods, and hyphenated techniques, with the aim of promoting the development of an optimal and practical protocol for the determination of CSF-histamine and/or CSF-histamine metabolites. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. A novel sample preparation method using rapid nonheated saponification method for the determination of cholesterol in emulsified foods.

    Science.gov (United States)

    Jeong, In-Seek; Kwak, Byung-Man; Ahn, Jang-Hyuk; Leem, Donggil; Yoon, Taehyung; Yoon, Changyong; Jeong, Jayoung; Park, Jung-Min; Kim, Jin-Man

    2012-10-01

    In this study, nonheated saponification was employed as a novel, rapid, and easy sample preparation method for the determination of cholesterol in emulsified foods. Cholesterol content was analyzed using gas chromatography with a flame ionization detector (GC-FID). The cholesterol extraction method was optimized for maximum recovery from baby food and infant formula. Under these conditions, the optimum extraction solvent was 10 mL ethyl ether per 1 to 2 g sample, and the saponification solution was 0.2 mL KOH in methanol. The cholesterol content in the products was determined to be within the certified range of certified reference materials (CRMs), NIST SRM 1544 and SRM 1849. The results of the recovery test performed using spiked materials were in the range of 98.24% to 99.45% with an relative standard devitation (RSD) between 0.83% and 1.61%. This method could be used to reduce sample pretreatment time and is expected to provide an accurate determination of cholesterol in emulsified food matrices such as infant formula and baby food. A novel, rapid, and easy sample preparation method using nonheated saponification was developed for cholesterol detection in emulsified foods. Recovery tests of CRMs were satisfactory, and the recoveries of spiked materials were accurate and precise. This method was effective and decreased the time required for analysis by 5-fold compared to the official method. © 2012 Institute of Food Technologists®

  14. A nanoparticle-based solid-phase extraction procedure followed by spectrofluorimetry to determine carbaryl in different water samples

    Energy Technology Data Exchange (ETDEWEB)

    Tabrizi, Ahad Bavili, E-mail: a.bavili@tbzmed.ac.ir, E-mail: abavilitabrizia@gmail.com [Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Rashidi, Mohammad Reza [Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Tabriz, (Iran, Islamic Republic of); Ostadi, Hadi [Department of Chemistry, Payam-e-noor University, Ardabil Branch, Ardabil (Iran, Islamic Republic of)

    2014-04-15

    In this study, a new method based on Fe{sub 3}O{sub 4} magnetite nanoparticles (MNPs) has been developed for the extraction, preconcentration and determination of trace amounts of carbaryl from environmental water samples. Fe{sub 3}O{sub 4} MNPs were synthesized and modified by the surfactant sodium dodecyl sulfate (SDS), then successfully applied for the extraction of carbaryl and its determination by spectrofluorimetry. Main factors affecting the adsolubilization of carbaryl such as the amount of SDS, pH value, standing time, desorption solvent and maximal extraction volume were optimized. Under the selected conditions, carbaryl could be quantitatively extracted. Acceptable recoveries (84.5-91.9%) and relative standard deviations (6.2%) were achieved in analyzing spiked water samples. A concentration factor of 20 was achieved by the extraction of 100 mL of environmental water samples. The limit of detection and quantification were found to be 2.1 and 6.9 μg L{sup -1}, respectively. The proposed method was successfully applied for the extraction and determination of carbaryl in environmental water samples. (author)

  15. Rapid method to determine actinides and 89/90Sr in limestone and marble samples

    International Nuclear Information System (INIS)

    Maxwell, S.L.; Culligan, Brian; Hutchison, J.B.; Utsey, R.C.; Sudowe, Ralf; McAlister, D.R.

    2016-01-01

    A new method for the determination of actinides and radiostrontium in limestone and marble samples has been developed that utilizes a rapid sodium hydroxide fusion to digest the sample. Following rapid pre-concentration steps to remove sample matrix interferences, the actinides and 89 / 90 Sr are separated using extraction chromatographic resins and measured radiometrically. The advantages of sodium hydroxide fusion versus other fusion techniques will be discussed. This approach has a sample preparation time for limestone and marble samples of <4 h. (author)

  16. Use of multilevel modeling for determining optimal parameters of heat supply systems

    Science.gov (United States)

    Stennikov, V. A.; Barakhtenko, E. A.; Sokolov, D. V.

    2017-07-01

    The problem of finding optimal parameters of a heat-supply system (HSS) is in ensuring the required throughput capacity of a heat network by determining pipeline diameters and characteristics and location of pumping stations. Effective methods for solving this problem, i.e., the method of stepwise optimization based on the concept of dynamic programming and the method of multicircuit optimization, were proposed in the context of the hydraulic circuit theory developed at Melentiev Energy Systems Institute (Siberian Branch, Russian Academy of Sciences). These methods enable us to determine optimal parameters of various types of piping systems due to flexible adaptability of the calculation procedure to intricate nonlinear mathematical models describing features of used equipment items and methods of their construction and operation. The new and most significant results achieved in developing methodological support and software for finding optimal parameters of complex heat supply systems are presented: a new procedure for solving the problem based on multilevel decomposition of a heat network model that makes it possible to proceed from the initial problem to a set of interrelated, less cumbersome subproblems with reduced dimensionality; a new algorithm implementing the method of multicircuit optimization and focused on the calculation of a hierarchical model of a heat supply system; the SOSNA software system for determining optimum parameters of intricate heat-supply systems and implementing the developed methodological foundation. The proposed procedure and algorithm enable us to solve engineering problems of finding the optimal parameters of multicircuit heat supply systems having large (real) dimensionality, and are applied in solving urgent problems related to the optimal development and reconstruction of these systems. The developed methodological foundation and software can be used for designing heat supply systems in the Central and the Admiralty regions in

  17. Improved sample treatment for the determination of insoluble soap in sewage sludge samples by liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Cantarero, Samuel; Zafra-Gómez, A; Ballesteros, O; Navalón, A; Vílchez, J L; Crovetto, G; Verge, C; de Ferrer, J A

    2010-09-15

    A new selective and sensitive method for the determination of insoluble fatty acid salts (soap) in sewage sludge samples is proposed. The method involves a clean up of sample with petroleum ether, the conversion of calcium and magnesium insoluble salts into soluble potassium salts, potassium salts extraction with methanol, and a derivatization procedure previous to the liquid chromatography with fluorescence detection (LC-FLD) analysis. Three different extraction techniques (Soxhlet, microwave-assisted extraction and ultrasounds) were compared and microwave-assisted extraction (MAE) was selected as appropriate for our purpose. This allowed to reduce the extraction time and solvent waste (50 mL of methanol in contrast with 250 mL for Soxhlet procedure). The absence of matrix effect was demonstrated with two standards (C(13:0) and C(17:0)) that are not commercials and neither of them has been detected in sewage sludge samples. Therefore, it was possible to evaluate the matrix effect since both standards have similar environmental behaviour (adsorption and precipitation) to commercial soaps (C(10:0)-C(18:0)). The method was successfully applied to samples from different sources and consequently, with different composition. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  18. DETERMINATION OF OPTIMAL CONTOURS OF OPEN PIT MINE DURING OIL SHALE EXPLOITATION, BY MINEX 5.2.3. PROGRAM

    Directory of Open Access Journals (Sweden)

    Miroslav Ignjatović

    2013-04-01

    Full Text Available By examination and determination of optimal solution of technological processes of exploitation and oil shale processing from Aleksinac site and with adopted technical solution and exploitation of oil shale, derived a technical solution that optimize contour of the newly defined open pit mine. In the world, this problem is solved by using a computer program that has become the established standard for quick and efficient solution for this problem. One of the computer’s program, which can be used for determination of the optimal contours of open pit mines is Minex 5.2.3. program, produced in Australia in the Surpac Minex Group Pty Ltd Company, which is applied at the Mining and Metallurgy Institute Bor (no. of licenses are SSI - 24765 and SSI - 24766. In this study, authors performed 11 optimization of deposit geo - models in Minex 5.2.3. based on the tests results, performed in a laboratory for soil mechanics of Mining and Metallurgy Institute, Bor, on samples from the site of Aleksinac deposits.

  19. Determination of natural alpha-emitting isotopes of uranium and thorium in environmental and geological samples

    International Nuclear Information System (INIS)

    Crespo, M.T.

    1996-01-01

    It is described the complete radiochemical procedure used for the determination of uranium and thorium isotopes in environmental and geological samples by alpha spectrometry. Source preparation methods, alpha-counting and spectral analysis are also included

  20. Blood oxygen saturation determined by transmission spectrophotometry of hemolyzed blood samples

    Science.gov (United States)

    Malik, W. M.

    1967-01-01

    Use of the Lambert-Beer Transmission Law determines blood oxygen saturation of hemolyzed blood samples. This simplified method is based on the difference in optical absorption properties of hemoglobin and oxyhemoglobin.

  1. Technical developments for accurate determination of amount of samples used for TOF measurements

    Directory of Open Access Journals (Sweden)

    Terada Kazushi

    2017-01-01

    Full Text Available Activity determination of 241,243Am samples has been performed with two separate methods of calorimetry and gamma-ray spectroscopy. Decay heat measurements of the samples were carried out by using a calorimeter, and activities of the samples were accurately determined with uncertainties less than 0.45%. The primary source of uncertainty in the calorimetric method is the accuracy of available half-life data. Gamma-ray detection efficiencies of a HPGe detector were determined with uncertainties of 1.5% by combining measured efficiencies and Monte Carlo simulation. Activities of the samples were determined with uncertainties less than 2.0% by gamma-ray spectroscopy and were concordant with those of the calorimetry.

  2. Simultaneous determination and validation of emtricitabine, rilpivirine and tenofovir from biological samples using LC and CE methods.

    Science.gov (United States)

    Gumustas, Mehmet; Caglayan, Mehmet Gokhan; Onur, Feyyaz; Ozkan, Sibel A

    2018-04-01

    A combination of antiretroviral agents is frequently used in effective treatment of the human immunodeficiency virus infection. In this study, two different separation methods are presented for the simultaneous determination of emtricitabine, rilpivirine and tenofovir from raw materials and urine samples. Developed liquid chromatography and capillary electrophoresis methods were thoroughly optimized for high analytical performances. Optimization of multiple variables at the same time by performing a minimum number of experiments was achieved by the Box-Behnken design, which is an experimental design in response surface methodology, in capillary electrophoresis. The results of the experimental design ensure minimum analysis time with well-separated analytes. Separation conditions, such as different stationary phases, pH level, organic modifiers and temperatures in liquid chromatography method, were also optimized. In particular, among stationary phases, the core-shell column especially enhanced the effectiveness of separation in liquid chromatography. Both methods were fully validated and applied to real samples. The main advantage of the developed methods is the separation of the drug combination in a short time with high efficiency and without any time-consuming steps. Copyright © 2017 John Wiley & Sons, Ltd.

  3. Optimization of Sample Preparation and Instrumental Parameters for the Rapid Analysis of Drugs of Abuse in Hair samples by MALDI-MS/MS Imaging

    Science.gov (United States)

    Flinders, Bryn; Beasley, Emma; Verlaan, Ricky M.; Cuypers, Eva; Francese, Simona; Bassindale, Tom; Clench, Malcolm R.; Heeren, Ron M. A.

    2017-08-01

    Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) has been employed to rapidly screen longitudinally sectioned drug user hair samples for cocaine and its metabolites using continuous raster imaging. Optimization of the spatial resolution and raster speed were performed on intact cocaine contaminated hair samples. The optimized settings (100 × 150 μm at 0.24 mm/s) were subsequently used to examine longitudinally sectioned drug user hair samples. The MALDI-MS/MS images showed the distribution of the most abundant cocaine product ion at m/z 182. Using the optimized settings, multiple hair samples obtained from two users were analyzed in approximately 3 h: six times faster than the standard spot-to-spot acquisition method. Quantitation was achieved using longitudinally sectioned control hair samples sprayed with a cocaine dilution series. A multiple reaction monitoring (MRM) experiment was also performed using the `dynamic pixel' imaging method to screen for cocaine and a range of its metabolites, in order to differentiate between contaminated hairs and drug users. Cocaine, benzoylecgonine, and cocaethylene were detectable, in agreement with analyses carried out using the standard LC-MS/MS method. [Figure not available: see fulltext.

  4. DETERMINATION ОF DRESS ROLL OPTIMAL RADIUS WHILE PRODUCING PARTS WITH TROCHOIDAL PROFILE

    Directory of Open Access Journals (Sweden)

    E. N. Yankevich

    2008-01-01

    Full Text Available The paper considers determination of the dress roll optimal radius while producing parts having trohoidal profile with the help of grinding method that presupposes application of grinding disk. In this case disk profile has been cut-in by diamond dressing. Two methods for determination of calculation of the dress roll optimal radius have been proposed in the paper. On the basis of the satellite gear of the planetary pin reducer whose profile presents a trochoid it has been shown that the obtained results pertaining to two proposed methods conform with each other.

  5. A pyrolysis/gas chromatographic method for the determination of hydrogen in solid samples

    Science.gov (United States)

    Carr, R. H.; Bustin, R.; Gibson, E. K.

    1987-01-01

    A method is described for the determination of hydrogen in solid samples. The sample is heated under vacuum after which the evolved gases are separated by gas chromatography with a helium ionization detector. The system is calibrated by injecting known amounts of hydrogen, as determined manometrically. The method, which is rapid and reliable, was checked for a variety of lunar soils; the limit of detection is about 10 ng of hydrogen.

  6. Simple Modification of Karl-Fischer Titration Method for Determination of Water Content in Colored Samples

    OpenAIRE

    Eva Tavčar; Erika Turk; Samo Kreft

    2012-01-01

    The most commonly used technique for water content determination is Karl-Fischer titration with electrometric detection, requiring specialized equipment. When appropriate equipment is not available, the method can be performed through visual detection of a titration endpoint, which does not enable an analysis of colored samples. Here, we developed a method with spectrophotometric detection of a titration endpoint, appropriate for moisture determination of colored samples. The reaction takes p...

  7. Determination of artificial and natural radionuclides and others trace elements in environmental samples form Antarctica

    International Nuclear Information System (INIS)

    Schuch, L.A.; Godoy, J.M.; Nordemann, D.J.R.

    1994-01-01

    The results of the radioactive elements concentrations, determined by gamma spectrometry and the others trace elements determined by neutron activation analysis of several environmental samples (soils, marine sediments, algae mosses and lichens) in Comandante Ferraz Antartica Station are presented. The high concentrations of Cs-137 were found in lichens and mosses samples and the soils and sediments showed concentrations of natural radionuclides. (C.G.C.). 8 refs, 1 fig, 3 tabs

  8. Determination of Magnesium in Needle Biopsy Samples of Muscle Tissue by Means of Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Brune, D; Sjoeberg, H E

    1964-07-15

    Magnesium has been determined by means of neutron-activation analysis in needle biopsy samples of the order of magnitude 1 mg dry weight. The procedure applied was to extract the Mg-27 activity from irradiated muscle tissue with concentrated hydrochloric acid followed by a fast hydroxide precipitation and gamma-spectrometric measurements. The Mg activity was recovered in the muscle tissue samples to (97 {+-} 2) per cent. The sensitivity for the magnesium determination is estimated as 0.3 {mu}g.

  9. An analytical method for the determination of plutonium in autopsy samples

    International Nuclear Information System (INIS)

    Santori, G.

    1983-01-01

    A sensitive method for the determination of plutonium in autopsy samples is described. After a suitable chemical pretreatment of the samples the plutonium is separated by extraction chromatography with tri-n-octylphosphine oxide (TOPO) supported on microporus polyethylene. After electrodeposition of plutonium the activity is counted by alpha spectroscopy. The global yield was 75-80%. The reagent blank activity was such to allow the determination of some femtocuries of plutonium

  10. On-line determination of manganese in solid seafood samples by flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Yebra, M.C.; Moreno-Cid, A.

    2003-01-01

    Manganese is extracted on-line from solid seafood samples by a simple continuous ultrasound-assisted extraction system (CUES). This system is connected to an on-line manifold, which permits the flow-injection flame atomic absorption spectrometric determination of manganese. Optimisation of the continuous leaching procedure is performed by an experimental design. The proposed method allows the determination of manganese with a relative standard deviation of 0.9% for a sample containing 23.4 μg g -1 manganese (dry mass). The detection limit is 0.4 μg g -1 (dry mass) for 30 mg of sample and the sample throughput is ca. 60 samples per hour. Accurate results are obtained by measuring TORT-1 certified reference material. The procedure is finally applied to mussel, tuna, sardine and clams samples

  11. Determination of 90Sr in environmental samples by microwave assisted digestion - chromatographic separation

    International Nuclear Information System (INIS)

    Torres, J.M.; Llaurado, M.; Rauret, G.

    1998-01-01

    The stages involved in the determination of 90 Sr in environmental samples are: sample attack, radiochemical separation (of both 90 Sr and its progeny 90 Y) and measurement. For the determination of 90 Sr, the introduction of microwave-assisted digestion methods has improved acid attack by drastically decreasing both digestion time and the volume of acidic reagents. Recent studies describe many applications of microwave-assisted methods for the determination of inorganic and organometallic compounds in several matrices. We have recently studied the microwave-assisted digestion of soils for the 90 Sr determination. The presented work extends the application of microwaves for the 90 Sr determination to other environmental samples such as sediments, vegetation and milk. An open-focused microwave system, which accepts large samples intakes usually required for radioanalytical chemistry due to the low level content of radionuclides in environmental samples, was used. This system can handle up to 10 g of sample intake which, in many cases, is enough to have acceptable limits of detection. Different digestion procedures are optimised for each matrix studied, paying special attention to the microwave power, the time of digestion and the volume of acidic reagents. Once the sample is in solution a new separation procedure using a specific resin -Sr.Spec- is applied and the measurement is performed by liquid scintillation. The results obtained are compared with a previously optimised method based on liquid-liquid extraction of 90 Y and Cerenkov radiation measurement

  12. Determination of vanadium in steel and geological samples by its extraction and spectrophotometric determination using 2,3-dihydroxynaphthalene

    International Nuclear Information System (INIS)

    Mondal, R.K.; Tarafder, P.K.; Rathore, D.P.S.

    2013-01-01

    A new and simple method for extraction and spectrophotometric determination of vanadium has been described. Iron has been removed from the sample solution by its prior extraction with MIBK from concentrated HCl medium (∼6 M). Vanadium has been determined in the form of a colored complex with 2,3-dihydroxynaphthalene after its extraction into MIBK. The method is at least 5 fold more sensitive to BPHA method. The molar absorptivity of the complex at 530 nm being 1.5 x 10 4 Lmol -1 cm -1 . For samples having >5 fold excess concentration of TiO 2 , a prior separation of TiO 2 as its (Ti (OH) (HND) 3 ) complex is a must. The method has been successfully applied to different rock, soil and steel samples. (author)

  13. Burn-up determination of irradiated thoria samples by isotope dilution-thermal ionisation mass spectrometry

    International Nuclear Information System (INIS)

    Aggarwal, S.K.; Jaison, P.G.; Telmore, V.M.; Shah, R.V.; Sant, V.L.; Sasibhushan, K.; Parab, A.R.; Alamelu, D.

    2010-03-01

    Burn-up was determined experimentally using thermal ionization mass spectrometry for two samples from ThO 2 bundles irradiated in KAPS-2. This involved quantitative dissolution of the irradiated fuel samples followed by separation and determination of Th, U and a stable fission product burn-up monitor in the dissolved fuel solution. Stable fission product 148 Nd was used as a burn-up monitor for determining the number of fissions. Isotope Dilution-Thermal Ionisation Mass Spectrometry (ID-TIMS) using natural U, 229 Th and enriched 142 Nd as spikes was employed for the determination of U, Th and Nd, respectively. Atom % fission values of 1.25 ± 0.03 were obtained for both the samples. 232 U content in 233 U determined by alpha spectrometry was about 500 ppm and this was higher by a factor of 5 compared to the theoretically predicted value by ORIGEN-2 code. (author)

  14. Determination of 237Np in environmental and nuclear samples: A review of the analytical method

    International Nuclear Information System (INIS)

    Thakur, P.; Mulholland, G.P.

    2012-01-01

    A number of analytical methods has been developed and used for the determination of neptunium in environmental and nuclear fuel samples using alpha, ICP–MS spectrometry, and other analytical techniques. This review summarizes and discusses development of the radiochemical procedures for separation of neptunium (Np), since the beginning of the nuclear industry, followed by a more detailed discussion on recent trends in the separation of neptunium. This article also highlights the progress in analytical methods and issues associated with the determination of neptunium in environmental samples. - Highlights: ► Determination of Np in environmental and nuclear samples is reviewed. ► Various analytical methods used for the determination of Np are listed. ► Progress and issues associated with the determination of Np are discussed.

  15. Determination of natural uranium, thorium and radium isotopes in water and soil samples by alpha spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Le Cong; Tao, Chau Van; Thong, Luong Van; Linh, Duong Mong [University of Science Ho Chi Minh City (Viet Nam). Faculty of Physics and Engineering Physics; Dong, Nguyen Van [University of Science Ho Chi Minh City (Viet Nam). Faculty of Chemistry

    2011-08-15

    In this study, a simple procedure for the determination of natural uranium, thorium and radium isotopes in water and soil samples by alpha spectroscopy is described. This procedure allows a sequential extraction polonium, uranium, thorium and radium radionuclides from the same sample in two to three days. It was tested and validated with the analysis of certified reference materials from the IAEA. (orig.)

  16. Determination of heavy metals in groundwater samples - ICP-MS analysis and evaluation

    International Nuclear Information System (INIS)

    Leiterer, M.; Muench, U.

    1994-01-01

    An analytical programme which permits the direct, simultaneous determination of Al, As, Cd, Cr, Cu, Mn, Ni, Pb and Zn in groundwater samples was developed for ICP-MS. Spectral mass interferences, attributable to great differences in groundwater matrices, precision and accuracy have been discussed. The evaluation of analytical results was demonstrated for selected sampling points of the groundwater observation network of Thuringia. (orig.)

  17. Application of neutron activation analysis to trace elements determinations in lung samples

    International Nuclear Information System (INIS)

    Rogero, S.O.

    1991-01-01

    The purpose of this work was to apply the instrumental neutron activation analysis method to determine trace elements in lung samples from smokers and non smokers. Samples of lung tissues and lymph nodes from pulmonary hilum analyzed were collected from autopsies by researchers from Faculdade de Medicina da USP. (author)

  18. Procedure for determination of alpha emitters in urine and dregs samples

    International Nuclear Information System (INIS)

    Serdeiro, Nelida H.

    2005-01-01

    The purpose of this work is to establish the procedure for the identification and quantification of emitting alpha radionuclides in urine and dregs samples. This procedure are applied to all laboratories of the countries of the Project ARCAL LXXVII that determinate alpha emitting radionuclides in biological samples for biological assessment [es

  19. Radiochemical separation of actinides for their determination in environmental samples and waste products

    Energy Technology Data Exchange (ETDEWEB)

    Gleisberg, B [Nuclear Engineering and Analytics Rossendorf, Inc. (VKTA), Dresden (Germany)

    1997-03-01

    The determination of low level activities of actinides in environmental samples and waste products makes high demands on radiochemical separation methods. Artificial and natural actinides were analyzed in samples form the surrounding areas of NPP and of uranium mines, incorporation samples, solutions containing radioactive fuel, solutions and solids resutling from the process, and in wastes. The activities are measured by {alpha}-spectrometry and {gamma}-spectrometry. (DG)

  20. Role of NAA in determination and characterisation of sampling behaviours of multiple elements in CRMs

    International Nuclear Information System (INIS)

    Tian Weizhi; Ni Bangfa; Wang Pingsheng; Nie Huiling

    2002-01-01

    Taking the advantage of high precision and accuracy of neutron activation analysis (NAA), sampling constants have been determined for multielements in several international and Chinese reference materials. The suggested technique may be used for finding elements in existing CRMs qualified for quality control (QC) of small size samples (several mg or less), and characterizing sampling behaviors of multielements in new CRMs specifically made for QC of microanalysis. (author)