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Sample records for preparation detection limits

  1. What value, detection limits

    International Nuclear Information System (INIS)

    Currie, L.A.

    1986-01-01

    Specific approaches and applications of LLD's to nuclear and ''nuclear-related'' measurements are presented in connection with work undertaken for the U.S. Nuclear Regulatory Commission and the International Atomic Energy Agency. In this work, special attention was given to assumptions and potential error sources, as well as to different types of analysis. For the former, the authors considered random and systematic error associated with the blank and the calibration and sample preparation processes, as well as issues relating to the nature of the random error distributions. Analysis types considered included continuous monitoring, ''simple counting'' involving scalar quantities, and spectrum fitting involving data vectors. The investigation of data matrices and multivariate analysis is also described. The most important conclusions derived from this study are: that there is a significant lack of communication and compatibility resulting from diverse terminology and conceptual bases - including no-basis ''ad hoc'' definitions; that the distinction between detection decisions and detection limits is frequently lost sight of; and that quite erroneous LOD estimates follow from inadequate consideration of the actual variability of the blank, and systematic error associated with the blank, the calibration-recovery factor, matrix effects, and ''black box'' data reduction models

  2. Activation analysis. Detection limits

    International Nuclear Information System (INIS)

    Revel, G.

    1999-01-01

    Numerical data and limits of detection related to the four irradiation modes, often used in activation analysis (reactor neutrons, 14 MeV neutrons, photon gamma and charged particles) are presented here. The technical presentation of the activation analysis is detailed in the paper P 2565 of Techniques de l'Ingenieur. (A.L.B.)

  3. Extending the detection limit of dopants for focused ion beam prepared semiconductor specimens examined by off-axis electron holography

    DEFF Research Database (Denmark)

    Cooper, David; Rivallin, Pierrette; Hartmann, Jean-Michel

    2009-01-01

    Silicon specimens containing p-n junctions have been prepared for examination by off-axis electron holography using focused ion beam (FIB) milling. FIB milling modifies the surfaces of the specimens due to gallium implantation and the creation of defects which has the effect of reducing the active...

  4. Material limitations on the detection limit in refractometry.

    Science.gov (United States)

    Skafte-Pedersen, Peder; Nunes, Pedro S; Xiao, Sanshui; Mortensen, Niels Asger

    2009-01-01

    We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η, with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm) of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly.

  5. Material Limitations on the Detection Limit in Refractometry

    Directory of Open Access Journals (Sweden)

    Niels Asger Mortensen

    2009-10-01

    Full Text Available We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly.

  6. Detection Limits for Nanoscale Biosensors

    National Research Council Canada - National Science Library

    Sheehan, Paul E; Whitman, Lloyd J

    2005-01-01

    We examine through analytical calculations and finite element simulations how the detection efficiency of disk and wire-like biosensors in unmixed fluids varies with size from the micrometer to nanometer scales...

  7. Material limitations on the detection limit in refractometry

    DEFF Research Database (Denmark)

    Skafte-Pedersen, Peder; Nunes, Pedro; Xiao, Sanshui

    2009-01-01

    We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and...

  8. Material Limitations on the Detection Limit in Refractometry

    OpenAIRE

    Skafte-Pedersen, Peder; Nunes, Pedro S.; Xiao, Sanshui; Mortensen, Niels Asger

    2009-01-01

    We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a...

  9. Limits of detection and decision. Part 4

    International Nuclear Information System (INIS)

    Voigtman, E.

    2008-01-01

    Probability density functions (PDFs) have been derived for a number of commonly used limit of detection definitions, including several variants of the Relative Standard Deviation of the Background-Background Equivalent Concentration (RSDB-BEC) method, for a simple linear chemical measurement system (CMS) having homoscedastic, Gaussian measurement noise and using ordinary least squares (OLS) processing. All of these detection limit definitions serve as both decision and detection limits, thereby implicitly resulting in 50% rates of Type 2 errors. It has been demonstrated that these are closely related to Currie decision limits, if the coverage factor, k, is properly defined, and that all of the PDFs are scaled reciprocals of noncentral t variates. All of the detection limits have well-defined upper and lower limits, thereby resulting in finite moments and confidence limits, and the problem of estimating the noncentrality parameter has been addressed. As in Parts 1-3, extensive Monte Carlo simulations were performed and all the simulation results were found to be in excellent agreement with the derived theoretical expressions. Specific recommendations for harmonization of detection limit methodology have also been made

  10. Establishment of limits of detection and decision

    International Nuclear Information System (INIS)

    Mende, O.; Michel, R.

    1995-01-01

    The purpose of this project was to develop and test procedures to establish limits of decision and detection for spectrometric nuclear radiation measurements. Beside the determination of the limits of application of DIN 25482 part 2 and 5 - both primarily suitable for high resoluted spectra areas -the statistical model was expanded in such a way that henceforth blanks and influences of sample treatment can also be taken into account; the corresponding procedures to calculate the limits of decision and detection have a high precision. Additional procedures of calculation were developed to take the special characteristics of the analysis of complex spectra areas into account. (orig.) [de

  11. Pushing the limits of NAA. Accuracy, uncertainty and detection limits

    International Nuclear Information System (INIS)

    Greenberg, R.R.

    2008-01-01

    This paper describes some highlights from the author's efforts to improve neutron activation analysis (NAA) detection limits through development and optimization of radiochemical separations, as well as to improve the overall accuracy of NAA measurements by identifying, quantifying and reducing measurement biases and uncertainties. Efforts to demonstrate the metrological basis of NAA, and to establish it as a 'Primary Method of Measurement' will be discussed. (author)

  12. Limits of qualitative detection and quantitative determination

    International Nuclear Information System (INIS)

    Curie, L.A.

    1976-01-01

    The fact that one can find a series of disagreeing and limiting definitions of the detection limit leads to the reinvestigation of the problems of signal detection and signal processing in analytical and nuclear chemistry. Three cut-off levels were fixed: Lsub(C) - the net signal level (sensitivity of the equipment), above which an observed signal can be reliably recognized as 'detected'; Lsub(D) - the 'true' net signal level, from which one can a priori expect a detection; Lsub(Q) - the level at which the measuring accuracy is sufficient for quantitative determination. Exact definition equations as well as a series of working formulae are given for the general analytical case and for the investigation of radioactivity. As it is assumed that the radioactivity of the Poisson distribution is determined, it is dealt with in such a manner that precise limits can be derived for short-lived and long-lived radionuclides with or without disturbance. The fundamentals are made clear by simple examples for spectrophotometry and radioactivity and by a complicated example for activation analysis in which one must choose between alternative nuclear reactions. (orig./LH) [de

  13. The limit of detection for explosives in spectroscopic differential reflectometry

    Science.gov (United States)

    Dubroca, Thierry; Vishwanathan, Karthik; Hummel, Rolf E.

    2011-05-01

    In the wake of recent terrorist attacks, such as the 2008 Mumbai hotel explosion or the December 25th 2009 "underwear bomber", our group has developed a technique (US patent #7368292) to apply differential reflection spectroscopy to detect traces of explosives. Briefly, light (200-500 nm) is shone on a surface such as a piece of luggage at an airport. Upon reflection, the light is collected with a spectrometer combined with a CCD camera. A computer processes the data and produces in turn a differential reflection spectrum involving two adjacent areas of the surface. This differential technique is highly sensitive and provides spectroscopic data of explosives. As an example, 2,4,6, trinitrotoluene (TNT) displays strong and distinct features in differential reflectograms near 420 nm. Similar, but distinctly different features are observed for other explosives. One of the most important criteria for explosive detection techniques is the limit of detection. This limit is defined as the amount of explosive material necessary to produce a signal to noise ratio of three. We present here, a method to evaluate the limit of detection of our technique. Finally, we present our sample preparation method and experimental set-up specifically developed to measure the limit of detection for our technology. This results in a limit ranging from 100 nano-grams to 50 micro-grams depending on the method and the set-up parameters used, such as the detector-sample distance.

  14. Global Health: Preparation for Working in Resource-Limited Settings.

    Science.gov (United States)

    St Clair, Nicole E; Pitt, Michael B; Bakeera-Kitaka, Sabrina; McCall, Natalie; Lukolyo, Heather; Arnold, Linda D; Audcent, Tobey; Batra, Maneesh; Chan, Kevin; Jacquet, Gabrielle A; Schutze, Gordon E; Butteris, Sabrina

    2017-11-01

    Trainees and clinicians from high-income countries are increasingly engaging in global health (GH) efforts, particularly in resource-limited settings. Concomitantly, there is a growing demand for these individuals to be better prepared for the common challenges and controversies inherent in GH work. This is a state-of-the-art review article in which we outline what is known about the current scope of trainee and clinician involvement in GH experiences, highlight specific considerations and issues pertinent to GH engagement, and summarize preparation recommendations that have emerged from the literature. The article is focused primarily on short-term GH experiences, although much of the content is also pertinent to long-term work. Suggestions are made for the health care community to develop and implement widely endorsed preparation standards for trainees, clinicians, and organizations engaging in GH experiences and partnerships. Copyright © 2017 by the American Academy of Pediatrics.

  15. Sample Preparation for Electron Probe Microanalysis—Pushing the Limits

    Science.gov (United States)

    Geller, Joseph D.; Engle, Paul D.

    2002-01-01

    important, and, under certain conditions, may even be the limiting factor in the analytical uncertainty budget. This paper considers preparing samples to get known geometries. It will not address the analysis of samples with irregular, unprepared surfaces or unknown geometries. PMID:27446757

  16. Sample Preparation for Electron Probe Microanalysis-Pushing the Limits.

    Science.gov (United States)

    Geller, Joseph D; Engle, Paul D

    2002-01-01

    important, and, under certain conditions, may even be the limiting factor in the analytical uncertainty budget. This paper considers preparing samples to get known geometries. It will not address the analysis of samples with irregular, unprepared surfaces or unknown geometries.

  17. Experience with dose limitation during preparations for sea dumping operations

    International Nuclear Information System (INIS)

    Fieuw, G.; Voorde, N. van de; Baekelandt, L.

    1982-01-01

    Since 1967 low-level radioactive wastes from operational nuclear facilities in Belgium have been dumped into the sea. The dumping is carried out in accordance with the recommendations issued by the IAEA under the London Convention. All these dumping operations have taken place under the surveillance of the Nuclear Energy Agency of the OECD. To limit the doses received by workers and the public during the various phases leading up to sea dumping, appropriate measures are required in connection with waste treatment and packaging, limitation of radiation levels, storage and handling, organization and selection of the means of transport and organization and means of monitoring. Although treatment and handling at the nuclear sites are entrusted to occupationally exposed workers, temporary labour is used for the transport and handling operations. Effective treatment and packaging reduce the risk of internal exposure to a negligible value. Meticulous planning and permanent personnel monitoring reduce the doses received by the workers to acceptable values not exceeding the statutory dose limits. The doses received by personnel involved in the preparations for sea dumping operations from 1967 to 1980 are given and a relationship is established between these doses and the activities handled. Experience shows that sea dumping operations do not entail unacceptable risks either for the workers concerned or for the population and allows us to optimize the methods used for loading, handling and transport. (author)

  18. Detection limits for radioanalytical counting techniques

    International Nuclear Information System (INIS)

    Hartwell, J.K.

    1975-06-01

    In low-level radioanalysis it is usually necessary to test the sample net counts against some ''Critical Level'' in order to determine if a given result indicates detection. This is an interpretive review of the work by Nicholson (1963), Currie (1968) and Gilbert (1974). Nicholson's evaluation of three different computational formulas for estimation of the ''Critical Level'' is discussed. The details of Nicholson's evaluation are presented along with a basic discussion of the testing procedures used. Recommendations are presented for calculation of confidence intervals, for reporting of analytical results, and for extension of the derived formula to more complex cases such as multiple background counts, multiple use of a single background count, and gamma spectrometric analysis

  19. Preparing a scientific manuscript in Linux: Today's possibilities and limitations.

    Science.gov (United States)

    Tchantchaleishvili, Vakhtang; Schmitto, Jan D

    2011-10-22

    Increasing number of scientists are enthusiastic about using free, open source software for their research purposes. Authors' specific goal was to examine whether a Linux-based operating system with open source software packages would allow to prepare a submission-ready scientific manuscript without the need to use the proprietary software. Preparation and editing of scientific manuscripts is possible using Linux and open source software. This letter to the editor describes key steps for preparation of a publication-ready scientific manuscript in a Linux-based operating system, as well as discusses the necessary software components. This manuscript was created using Linux and open source programs for Linux.

  20. On the lower of limit detection of radiometric systems

    International Nuclear Information System (INIS)

    Kamburov, H.; Boneva, S.

    1983-01-01

    The existing definitions of the quantity Asub(min), the lower detection limit, introduced as a characteristic of the sensitivity of radiometric systems are reviewed. A convenient way is found for comparing the different definitions by showing that each definition is connected with a specific value of the probability a of Type I error. The detection limits are calculated for a normal and Poisson distributions of the measured quantities. A criterion is proposed for the applicability of the normal distiribution to the problem of determining the lower detection limit

  1. Lower detectable limit of sulfur by fast neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shani, G; Cohen, D [Ben-Gurion Univ. of the Negev, Beersheba (Israel). Dept. of Nuclear Engineering

    1976-07-01

    For the purpose of air pollution research, the possibility of fast neutron activation analysis of sulfur was investigated. The only reaction that can be used for this purpose is S/sup 34/(n, p)P/sup 34/. A rabbit system was installed, synchronized with a 150 kV D-T neutron generator and an electronic analysing system. The whole system was operated so that the sample was irradiated for 10 sec and the 2.13 MeV ..gamma..-ray was counted for 10 sec. 5 samples were prepared containing sulfur from 0.5 to 0.1 g. Each measurement lasted 30 min and the activity was plotted as a function of sulfur weight. The relative error is increased very much when the amount of sulfur is below 0.1 g. This is what sets the lower detectable limit. Collection of more than 0.1 g of sulfur even during a long collection time means a very high SO/sub 2/ concentration in the air.

  2. 29 CFR 780.150 - Scope and limits of “preparation for market.”

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Scope and limits of âpreparation for market.â 780.150... STANDARDS ACT General Scope of Agriculture Preparation for Market § 780.150 Scope and limits of “preparation for market.” “Preparation for market” is also named as one of the practices which may be included in...

  3. Detection limit calculations for different total reflection techniques

    International Nuclear Information System (INIS)

    Sanchez, H.J.

    2000-01-01

    In this work, theoretical calculations of detection limits for different total-reflection techniques are presented.. Calculations include grazing incidence (TXRF) and gracing exit (GEXRF) conditions. These calculations are compared with detection limits obtained for conventional x-ray fluorescence (XRF). In order to compute detection limits the Shiraiwa and Fujino's model to calculate x-ray fluorescence intensities was used. This model made certain assumptions and approximations to achieve the calculations, specially in the case of the geometrical conditions of the sample, and the incident and takeoff beams. Nevertheless the calculated data of detection limits for conventional XRF and total-reflection XRF show a good agreement with previous results. The model proposed here allows to analyze the different sources of background and the influence of the excitation geometry, which contribute to the understanding of the physical processes involved in the XRF analysis by total reflection. Finally, a comparison between detection limits in total-reflection analysis at grazing incidence and at grazing exit is carried out. Here a good agreement with the theoretical predictions of the reversibility principle is found, showing that detection limits are similar for both techniques. (author)

  4. Microfluidic devices for sample preparation and rapid detection of foodborne pathogens

    DEFF Research Database (Denmark)

    Kant, Krishna; Shahbazi, Mohammad-Ali; Dave, Vivek Priy

    2018-01-01

    and improve the limit of detections. Integration of pathogen capturing bio-receptors on microfluidic devices is a crucial step, which can facilitate recognition abilities in harsh chemical and physical conditions, offering a great commercial benefit to the food-manufacturing sector. This article reviews...... diagnosis competences. This has prompted researchers to call the current status of detection approaches into question and leverage new technologies for superior pathogen sensing outcomes. Novel strategies mainly rely on incorporating all the steps from sample preparation to detection in miniaturized devices...... recent advances in current state-of-the-art of sample preparation and concentration from food matrices with focus on bacterial capturing methods and sensing technologies, along with their advantages and limitations when integrated into microfluidic devices for online rapid detection of pathogens in foods...

  5. Importance of the lower limit of detection in radiological safety

    International Nuclear Information System (INIS)

    Rafael Terol T.; Hermenegildo Maldonado M.

    1991-01-01

    The concept of the Lower Limit of Detection (LLD) it contributes in the solution of some problems related with the radiological safety, such as the realization of the tests of flight of the sealed radioactive sources; the determination of radioisotopes in environmental samples; the estimate of present radionuclides in polluted foods; in general, the detection of small quantities of radioactive materials present in materials of use or consumption by part of the man in his daily life; as the one Lower Limit of Detection is related with topics of statistics, in this work a small review of them is made, it was superficially discussed the mensuration problems related with the establishment of the Lower Limit of Detection

  6. Preparation of Dithizone Functionalized Polystyrene for Detecting Heavy Metal Ion

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hyeon Ho; Kim, Younghun [Kwangwoon University, Seoul (Korea, Republic of)

    2015-04-15

    Colorimetric sensors were usually used to detect specific metal ions using selective color change of solutions. While almost organic dye in colorimetric sensors detected single molecule, dithizone (DTZ) solution could be separately detected above 5 kinds of heavy metal ions by the change of clear color. Namely, DTZ could be used as multicolorimetric sensors. However, DTZ was generally used as aqueous type and paper/pellet-type DTZ was not reported yet. Therefore, in this work, polystyrene (PS) was prepared to composite with DTZ and then DTZ/PS pellet was obtained, which was used to selectively detect 10 kinds of heavy metal ions. When 10 ppm of Hg and Co ions was exposed in DTZ/PS pellets, clear color change was revealed. It is noted that DTZ/PS pellet could be used in detecting of heavy metal ion as dry type.

  7. Limited utility of preoperative studies in preparation for colostomy closure.

    Science.gov (United States)

    Pokorny, R M; Heniford, T; Allen, J W; Tuckson, W B; Galandiuk, S

    1999-04-01

    Numerous diagnostic and therapeutic practices are used in an attempt to reduce the morbidity of colostomy closures. Our principal aim was to evaluate the role of preoperative studies, specifically barium enemas and endoscopic examinations, performed before colostomy closures. Additionally, we wished to identify other practices involved in the perioperative management of patients undergoing colostomy closure that influenced morbidity. The records of 100 consecutive patients who underwent elective colostomy closure at University of Louisville Hospital between January 1989 and July 1995 were reviewed. Wound infection was the most common complication (12%). Various bowel preparations were equivalent in efficacy and did not influence the complication rate. Intermittent wound irrigation with antibiotics for 3 days postoperatively, via subcutaneous drains, was associated with a low incidence of incision infection. Preoperative barium enema or sigmoidoscopy were often performed but rarely useful. Performing these examinations merely increased hospital cost without a corresponding decline in morbidity.

  8. Confirmation of identity and detection limit in neutron activation analysis

    International Nuclear Information System (INIS)

    Yustina Tri Handayani; Slamet Wiyuniati; Tulisna

    2010-01-01

    Neutron Activation Analysis (NAA) based on neutron capture by nuclides. Of the various possibilities of radionuclides that occur, radionuclides and gamma radiation which provides the identity of the element were analyzed and the best sensitivity should be determined. Confirmation for elements in sediment samples was done theoretically and experimentally. The result of confirmation shows that Al, V, Cr K, Na, Ca and Zn were analyzed based on radionuclides of Al-28, V-52, Cr-51 , K-42, Na-24, Ca-48, Zn-65. Elements of Mg, Mn, Fe, Co were analyzed based on radionuclides of Mg-27, Mn-56, Fe-59, Co-60 through peak which the highest value of combined probability of radiation emission and efficiency. Cu can be analyzed through Cu-64 or Cu-66, but the second is more sensitive. Detection limit is determined at a certain measurement conditions carried out by a laboratory. Detection limit in the NAA is determined based on the Compton continue area by Curie method. The detection limit of Al, V, Ca, Mg, Mn, As, K, Na, Mg, Ce, Co, Cr, Fe, La, Sc, and Zn in sediment samples are 240, 27, 4750, 2600, 21, 3.3 , 75, 1.4, 1.8, 0.5, 2.7, 29, 1, 0.05, and 37 ppm. Analysis of Cu in sediments which concentrations of 98.6 ppm, Cu-66 is not detected. Tests using pure standard solutions of Cu obtained detection limit of 0.12 µg, or 7.9 ppm in samples of 15 mg. In general, the detection limit obtained was higher than the detection limit of the reference, it was caused by the differences in the sample matrix and analytical conditions. (author)

  9. Limits of Tumor Detectability in Nuclear Medicine and PET

    Directory of Open Access Journals (Sweden)

    Yusuf Emre Erdi

    2012-04-01

    Full Text Available Objective: Nuclear medicine is becoming increasingly important in the early detection of malignancy. The advantage of nuclear medicine over other imaging modalities is the high sensitivity of the gamma camera. Nuclear medicine counting equipment has the capability of detecting levels of radioactivity which exceed background levels by as little as 2.4 to 1. This translates to only a few hundred counts per minute on a regular gamma camera or as few as 3 counts per minute when using coincidence detection on a positron emission tomography (PET camera. Material and Methods: We have experimentally measured the limits of detectability using a set of hollow spheres in a Jaszczak phantom at various tumor-to-background ratios. Imaging modalities for this work were (1 planar, (2 SPECT, (3 PET, and (4 planar camera with coincidence detection capability (MCD. Results: When there is no background (infinite contrast activity present, the detectability of tumors is similar for PET and planar imaging. With the presence of the background activity , PET can detect objects in an order of magnitude smaller in size than that can be seen by conventional planar imaging especially in the typical clinical low (3:1 T/B ratios. The detection capability of the MCD camera lies between a conventional nuclear medicine (planar / SPECT scans and the detection capability of a dedicated PET scanner Conclusion: Among nuclear medicine’s armamentarium, PET is the closest modality to CT or MR imaging in terms of limits of detection. Modern clinical PET scanners have a resolution limit of 4 mm, corresponding to the detection of tumors with a volume of 0.2 ml (7 mm diameter in 5:1 T/B ratio. It is also possible to obtain better resolution limits with dedicated brain and animal scanners. The future holds promise in development of new detector materials, improved camera design, and new reconstruction algorithms which will improve sensitivity, resolution, contrast, and thereby further

  10. No evidence for an item limit in change detection.

    Directory of Open Access Journals (Sweden)

    Shaiyan Keshvari

    Full Text Available Change detection is a classic paradigm that has been used for decades to argue that working memory can hold no more than a fixed number of items ("item-limit models". Recent findings force us to consider the alternative view that working memory is limited by the precision in stimulus encoding, with mean precision decreasing with increasing set size ("continuous-resource models". Most previous studies that used the change detection paradigm have ignored effects of limited encoding precision by using highly discriminable stimuli and only large changes. We conducted two change detection experiments (orientation and color in which change magnitudes were drawn from a wide range, including small changes. In a rigorous comparison of five models, we found no evidence of an item limit. Instead, human change detection performance was best explained by a continuous-resource model in which encoding precision is variable across items and trials even at a given set size. This model accounts for comparison errors in a principled, probabilistic manner. Our findings sharply challenge the theoretical basis for most neural studies of working memory capacity.

  11. Improvement of detection limits of PIXE by substrate signal reduction

    International Nuclear Information System (INIS)

    Beaulieu, S.; Nejedly, Z.; Campbell, J.L.; Edwards, G.C.; Dias, G.M.

    2002-01-01

    Limits of detection (LODs) for aerosol samples collected using PIXE International cascade impactors, were improved approximately 50% after reducing the cross-sectional area of the analytical beam based on results obtained from microscope photographs of aerosol deposits. Improvements in LODs were most noticeable for selected elements collected on the smaller stages of the impactor (stages 1-3)

  12. Realistic limitations of detecting planets around young active stars

    Directory of Open Access Journals (Sweden)

    Pinfield D.

    2013-04-01

    Full Text Available Current planet hunting methods using the radial velocity method are limited to observing middle-aged main-sequence stars where the signatures of stellar activity are much less than on young stars that have just arrived on the main-sequence. In this work we apply our knowledge from the surface imaging of these young stars to place realistic limitations on the possibility of detecting orbiting planets. In general we find that the magnitude of the stellar jitter is directly proportional to the stellar vsini. For G and K dwarfs, we find that it is possible, for models with high stellar activity and low stellar vsini, to be able to detect a 1 MJupiter mass planet within 50 epochs of observations and for the M dwarfs it is possible to detect a habitable zone Earth-like planet in 10s of observational epochs.

  13. Preparing electrochemical active hierarchically porous carbons for detecting nitrite in drinkable water

    KAUST Repository

    Ding, Baojun

    2016-01-13

    A class of hierarchically porous carbons were prepared by a facile dual-templating approach. The obtained samples were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, Brunaner-Emmett-Teller measurement and electrochemical work station, respectively. The porous carbons could possess large specific surface area, interconnected pore structures, high conductivity and graphitizing degree. The resulting materials were used to prepare integrated modified electrodes. Based on the experimental results, the as-prepared hierarchically porous graphite (HPG) modified electrode showed the best electroactive performances toward the detection of nitrite with a detection limit of 8.1 × 10-3 mM. This HPG electrode was also repeatable and stable for 6 weeks. Moreover, this electrode was used for the determination of nitrite in drinkable water, and had acceptable recoveries. © The Royal Society of Chemistry 2016.

  14. Stochastic fluctuations and the detectability limit of network communities.

    Science.gov (United States)

    Floretta, Lucio; Liechti, Jonas; Flammini, Alessandro; De Los Rios, Paolo

    2013-12-01

    We have analyzed the detectability limits of network communities in the framework of the popular Girvan and Newman benchmark. By carefully taking into account the inevitable stochastic fluctuations that affect the construction of each and every instance of the benchmark, we come to the conclusion that the native, putative partition of the network is completely lost even before the in-degree/out-degree ratio becomes equal to that of a structureless Erdös-Rényi network. We develop a simple iterative scheme, analytically well described by an infinite branching process, to provide an estimate of the true detectability limit. Using various algorithms based on modularity optimization, we show that all of them behave (semiquantitatively) in the same way, with the same functional form of the detectability threshold as a function of the network parameters. Because the same behavior has also been found by further modularity-optimization methods and for methods based on different heuristics implementations, we conclude that indeed a correct definition of the detectability limit must take into account the stochastic fluctuations of the network construction.

  15. Determining the lower limit of detection for personnel dosimetry systems

    International Nuclear Information System (INIS)

    Roberson, P.L.; Carlson, R.D.

    1992-01-01

    A simple method for determining the lower limit of detection (LLD) for personnel dosimetry systems is described. The method relies on the definition of a critical level and a detection level. The critical level is the signal level above which a result has a small probability of being due to a fluctuation of the background. All results below the critical level should not be reported as an indication of a positive result. The detection level is the net signal level (i.e., dose received) above which there is a high confidence that a true reading will be detected and reported as a qualitatively positive result. The detection level may be identified as the LLD. A simple formula is derived to allow the calculation of the LLD under various conditions. This type of formula is being used by the Department of Energy Laboratory Accreditation Program (DOELAP) for personnel dosimetry. Participants in either the National Voluntary Laboratory Accreditation Program (NVLAP) for personnel dosimetry or DOELAP can use performance test results along with a measurement of background levels to estimate the LLDs for their dosimetry system. As long as they maintain their dosimetry system such that the LLDs are less than half the lower limit of the NVLAP or DOELAP test exposure ranges, dosimetry laboratories can avoid testing failures due to poor performance at very low exposures

  16. Sample preparation and detection device for infectious agents

    Science.gov (United States)

    Miles, Robin R.; Wang, Amy W.; Fuller, Christopher K.; Lemoff, Asuncion V.; Bettencourt, Kerry A.; Yu, June

    2003-06-10

    A sample preparation and analysis device which incorporates both immunoassays and PCR assays in one compact, field-portable microchip. The device provides new capabilities in fluid and particle control which allows the building of a fluidic chip with no moving parts, thus decreasing fabrication cost and increasing the robustness of the device. The device can operate in a true continuous (not batch) mode. The device incorporates magnetohydrodynamic (MHD) pumps to move the fluid through the system, acoustic mixing and fractionation, dielectropheretic (DEP) sample concentration and purification, and on-chip optical detection capabilities.

  17. Limiter discriminator detection of M-ary FSK signals

    Science.gov (United States)

    Fonseka, John P.

    1990-10-01

    The performance of limiter discriminator detection of M-ary FSK signals is analyzed at arbitrary modulation indices. It is shown that the error rate performance of limiter discriminator detection can be significantly improved by increasing the modulation index above 1/M. The optimum modulation index that minimizes the overall error probability is determined for the cases M = 2, 4 and 8. The analysis is carried out for wideband and bandlimited channels with Gaussian and second-order Butterworth filters. It is shown that the optimum modulation index depends on the signal/noise ratio (SNR), in a wideband channel, and on both SNR and time-bandwidth product in a bandlimited channel. Finally, it is shown that the optimum sampling instance in presence of a nonzero phase IF filter can be approximately determined by using only the worst case symbol pattern.

  18. Electronic cleansing for 24-h limited bowel preparation CT colonography using principal curvature flow

    NARCIS (Netherlands)

    van Ravesteijn, Vincent F.; Boellaard, Thierry N.; van der Paardt, Marije P.; Serlie, Iwo W. O.; de Haan, Margriet C.; Stoker, Jaap; van Vliet, Lucas J.; Vos, Frans M.

    2013-01-01

    CT colonography (CTC) is one of the recommended methods for colorectal cancer screening. The subject's preparation is one of the most burdensome aspects of CTC with a cathartic bowel preparation. Tagging of the bowel content with an oral contrast medium facilitates CTC with limited bowel

  19. Limited-preparation CT colonography in frail elderly patients: a feasibility study.

    LENUS (Irish Health Repository)

    Keeling, Aoife N

    2010-05-01

    Full colonic preparation can be onerous and may be poorly tolerated in frail elderly patients. The purpose of this study was to prospectively assess the image quality and diagnostic yield of limited-preparation CT colonography (CTC) in elderly patients with suspected colorectal cancer who were deemed medically unfit or unsuitable for colonoscopy.

  20. Detection limit of 238U by gamma spectrometry

    International Nuclear Information System (INIS)

    Tartaglione, A.; Blostein, J.; Mayer, R

    2004-01-01

    The detection limit of 238 U was determined by gamma spectra measurements of a depleted uranium sample using four NaI(Tl) scintillators in a compact arrangement.The sample was shielded with 5 and 10 cm of lead.Two different methods for data processing were used and compared.It was established that an appropriate array of 40 detectors could establish the presence of 220 g of this material in only 5 minutes [es

  1. Signal detection without finite-energy limits to quantum resolution

    OpenAIRE

    Luis Aina, Alfredo

    2013-01-01

    We show that there are extremely simple signal detection schemes where the finiteness of energy resources places no limit on the resolution. On the contrary, larger resolution can be obtained with lower energy. To this end the generator of the signal-dependent transformation encoding the signal information on the probe state must be different from the energy. We show that the larger the deviation of the probe state from being the minimum-uncertainty state, the better the resolution.

  2. Accuracy, precision, and lower detection limits (a deficit reduction approach)

    International Nuclear Information System (INIS)

    Bishop, C.T.

    1993-01-01

    The evaluation of the accuracy, precision and lower detection limits of the determination of trace radionuclides in environmental samples can become quite sophisticated and time consuming. This in turn could add significant cost to the analyses being performed. In the present method, a open-quotes deficit reduction approachclose quotes has been taken to keep costs low, but at the same time provide defensible data. In order to measure the accuracy of a particular method, reference samples are measured over the time period that the actual samples are being analyzed. Using a Lotus spreadsheet, data are compiled and an average accuracy is computed. If pairs of reference samples are analyzed, then precision can also be evaluated from the duplicate data sets. The standard deviation can be calculated if the reference concentrations of the duplicates are all in the same general range. Laboratory blanks are used to estimate the lower detection limits. The lower detection limit is calculated as 4.65 times the standard deviation of a set of blank determinations made over a given period of time. A Lotus spreadsheet is again used to compile data and LDLs over different periods of time can be compared

  3. Detection of colloidal silver chloride near solubility limit

    Science.gov (United States)

    Putri, K. Y.; Adawiah, R.

    2018-03-01

    Detection of nanoparticles in solution has been made possible by several means; one of them is laser-induced breakdown detection (LIBD). LIBD is able to distinguish colloids of various sizes and concentrations. This technique has been used in several solubility studies. In this study, the formation of colloids in a mixed system of silver nitrate and sodium chloride was observed by acoustic LIBD. Silver chloride has low solubility limit, therefore LIBD measurement is appropriate. Silver and chloride solutions with equal concentrations, set at below and above the solubility of silver chloride as the expected solid product, were mixed and the resulting colloids were observed. The result of LIBD measurement showed that larger particles were present as more silver and chloride introduced. However, once the concentrations exceeded the solubility limit of silver chloride, the detected particle size seemed to be decreasing, hence suggested the occurrence of coprecipitation process. This phenomenon indicated that the ability of LIBD to detect even small changes in colloid amounts might be a useful tool in study on formation and stability of colloids, i.e. to confirm whether nanoparticles synthesis has been successfully performed and whether the system is stable or not.

  4. Microfluidic devices for sample preparation and rapid detection of foodborne pathogens.

    Science.gov (United States)

    Kant, Krishna; Shahbazi, Mohammad-Ali; Dave, Vivek Priy; Ngo, Tien Anh; Chidambara, Vinayaka Aaydha; Than, Linh Quyen; Bang, Dang Duong; Wolff, Anders

    2018-03-10

    Rapid detection of foodborne pathogens at an early stage is imperative for preventing the outbreak of foodborne diseases, known as serious threats to human health. Conventional bacterial culturing methods for foodborne pathogen detection are time consuming, laborious, and with poor pathogen diagnosis competences. This has prompted researchers to call the current status of detection approaches into question and leverage new technologies for superior pathogen sensing outcomes. Novel strategies mainly rely on incorporating all the steps from sample preparation to detection in miniaturized devices for online monitoring of pathogens with high accuracy and sensitivity in a time-saving and cost effective manner. Lab on chip is a blooming area in diagnosis, which exploits different mechanical and biological techniques to detect very low concentrations of pathogens in food samples. This is achieved through streamlining the sample handling and concentrating procedures, which will subsequently reduce human errors and enhance the accuracy of the sensing methods. Integration of sample preparation techniques into these devices can effectively minimize the impact of complex food matrix on pathogen diagnosis and improve the limit of detections. Integration of pathogen capturing bio-receptors on microfluidic devices is a crucial step, which can facilitate recognition abilities in harsh chemical and physical conditions, offering a great commercial benefit to the food-manufacturing sector. This article reviews recent advances in current state-of-the-art of sample preparation and concentration from food matrices with focus on bacterial capturing methods and sensing technologies, along with their advantages and limitations when integrated into microfluidic devices for online rapid detection of pathogens in foods and food production line. Copyright © 2018. Published by Elsevier Inc.

  5. Weighted Polynomial Approximation for Automated Detection of Inspiratory Flow Limitation

    Directory of Open Access Journals (Sweden)

    Sheng-Cheng Huang

    2017-01-01

    Full Text Available Inspiratory flow limitation (IFL is a critical symptom of sleep breathing disorders. A characteristic flattened flow-time curve indicates the presence of highest resistance flow limitation. This study involved investigating a real-time algorithm for detecting IFL during sleep. Three categories of inspiratory flow shape were collected from previous studies for use as a development set. Of these, 16 cases were labeled as non-IFL and 78 as IFL which were further categorized into minor level (20 cases and severe level (58 cases of obstruction. In this study, algorithms using polynomial functions were proposed for extracting the features of IFL. Methods using first- to third-order polynomial approximations were applied to calculate the fitting curve to obtain the mean absolute error. The proposed algorithm is described by the weighted third-order (w.3rd-order polynomial function. For validation, a total of 1,093 inspiratory breaths were acquired as a test set. The accuracy levels of the classifications produced by the presented feature detection methods were analyzed, and the performance levels were compared using a misclassification cobweb. According to the results, the algorithm using the w.3rd-order polynomial approximation achieved an accuracy of 94.14% for IFL classification. We concluded that this algorithm achieved effective automatic IFL detection during sleep.

  6. Detection limits for nanoparticles in solution with classical turbidity spectra

    Science.gov (United States)

    Le Blevennec, G.

    2013-09-01

    Detection of nanoparticles in solution is required to manage safety and environmental problems. Spectral transmission turbidity method has now been known for a long time. It is derived from the Mie Theory and can be applied to any number of spheres, randomly distributed and separated by large distance compared to wavelength. Here, we describe a method for determination of size, distribution and concentration of nanoparticles in solution using UV-Vis transmission measurements. The method combines Mie and Beer Lambert computation integrated in a best fit approximation. In a first step, a validation of the approach is completed on silver nanoparticles solution. Verification of results is realized with Transmission Electronic Microscopy measurements for size distribution and an Inductively Coupled Plasma Mass Spectrometry for concentration. In view of the good agreement obtained, a second step of work focuses on how to manage the concentration to be the most accurate on the size distribution. Those efficient conditions are determined by simple computation. As we are dealing with nanoparticles, one of the key points is to know what the size limits reachable are with that kind of approach based on classical electromagnetism. In taking into account the transmission spectrometer accuracy limit we determine for several types of materials, metals, dielectrics, semiconductors the particle size limit detectable by such a turbidity method. These surprising results are situated at the quantum physics frontier.

  7. Detection limit for rate fluctuations in inhomogeneous Poisson processes

    Science.gov (United States)

    Shintani, Toshiaki; Shinomoto, Shigeru

    2012-04-01

    Estimations of an underlying rate from data points are inevitably disturbed by the irregular occurrence of events. Proper estimation methods are designed to avoid overfitting by discounting the irregular occurrence of data, and to determine a constant rate from irregular data derived from a constant probability distribution. However, it can occur that rapid or small fluctuations in the underlying density are undetectable when the data are sparse. For an estimation method, the maximum degree of undetectable rate fluctuations is uniquely determined as a phase transition, when considering an infinitely long series of events drawn from a fluctuating density. In this study, we analytically examine an optimized histogram and a Bayesian rate estimator with respect to their detectability of rate fluctuation, and determine whether their detectable-undetectable phase transition points are given by an identical formula defining a degree of fluctuation in an underlying rate. In addition, we numerically examine the variational Bayes hidden Markov model in its detectability of rate fluctuation, and determine whether the numerically obtained transition point is comparable to those of the other two methods. Such consistency among these three principled methods suggests the presence of a theoretical limit for detecting rate fluctuations.

  8. Detection limit for rate fluctuations in inhomogeneous Poisson processes.

    Science.gov (United States)

    Shintani, Toshiaki; Shinomoto, Shigeru

    2012-04-01

    Estimations of an underlying rate from data points are inevitably disturbed by the irregular occurrence of events. Proper estimation methods are designed to avoid overfitting by discounting the irregular occurrence of data, and to determine a constant rate from irregular data derived from a constant probability distribution. However, it can occur that rapid or small fluctuations in the underlying density are undetectable when the data are sparse. For an estimation method, the maximum degree of undetectable rate fluctuations is uniquely determined as a phase transition, when considering an infinitely long series of events drawn from a fluctuating density. In this study, we analytically examine an optimized histogram and a Bayesian rate estimator with respect to their detectability of rate fluctuation, and determine whether their detectable-undetectable phase transition points are given by an identical formula defining a degree of fluctuation in an underlying rate. In addition, we numerically examine the variational Bayes hidden Markov model in its detectability of rate fluctuation, and determine whether the numerically obtained transition point is comparable to those of the other two methods. Such consistency among these three principled methods suggests the presence of a theoretical limit for detecting rate fluctuations.

  9. Limits of detection of americium-241 in air

    International Nuclear Information System (INIS)

    Bereznai, T.

    1995-01-01

    Seven semiconductor detectors with various characteristics (type, form, size, etc.) were tested and compared in gamma-spectrometric assays for Am-241 aerosols in air. The problem at hand (determining a low activity or attaining a set detection limit (approx. 2 mBq/m 3 ) as soon as possible after sampling) was solved best by a large-volume n-type detector with a Be-window. In addition to the detector parameters commonly used (energy resolution and effectiveness), the peak-to-background ratio and the background counting rate at the gamma-energy of the nuclide to be determined are important criteria influencing the choice of equipment. (orig.) [de

  10. CARIES DETECTION WITH LASER FLUORESCENCE DEVICES. LIMITATIONS OF THEIR USE

    Directory of Open Access Journals (Sweden)

    Andreas Spaveras

    2017-03-01

    Data synthesis: DD and DDPen are useful devices for caries detection on the occlusal tooth surfaces. Their main advantages are the very high reproducibility of measurements (>0.90, the ease of handling and the quantification and monitoring capacity. Their main limitations are the relatively low specificity for enamel lesions, the necessity of unstained surfaces and absence of plaque and pastes during measurements and the absence of a universal, clinically functional calibration value (COV. Conclusion: Further studies are required for more reliable data analysis and clinical interpretation of the relevant results.

  11. Determination and Interpretation of Characteristic Limits for Radioactivity Measurements: Decision Threshhold, Detection Limit and Limits of the Confidence Interval

    International Nuclear Information System (INIS)

    2017-01-01

    Since 2004, the environment programme of the IAEA has included activities aimed at developing a set of procedures for analytical measurements of radionuclides in food and the environment. Reliable, comparable and fit for purpose results are essential for any analytical measurement. Guidelines and national and international standards for laboratory practices to fulfil quality assurance requirements are extremely important when performing such measurements. The guidelines and standards should be comprehensive, clearly formulated and readily available to both the analyst and the customer. ISO 11929:2010 is the international standard on the determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measuring ionizing radiation. For nuclear analytical laboratories involved in the measurement of radioactivity in food and the environment, robust determination of the characteristic limits of radioanalytical techniques is essential with regard to national and international regulations on permitted levels of radioactivity. However, characteristic limits defined in ISO 11929:2010 are complex, and the correct application of the standard in laboratories requires a full understanding of various concepts. This publication provides additional information to Member States in the understanding of the terminology, definitions and concepts in ISO 11929:2010, thus facilitating its implementation in Member State laboratories.

  12. Preparation of conjugated poly(ethyl acetylene carboxylate) as optical limiter of laser radiation

    International Nuclear Information System (INIS)

    Allaf, A. W.; Al-Zier, A.; Al-Naima, D.

    2009-03-01

    The optical limiting action of poly (ethylacetylene carboxylate) dissolved in dichloroethane were investigated under irradiation with 8 ns laser pulses at 532 nm. The optical limiting measurements were performed at a series of concentrations. The threshold limiting fluence was observed for high concentrations at 5 J/cm 2 with a transmission of about 20 %. No optical limiting action was observed at very low concentration of the prepared polymer in the dichloroethane solvent. The observed data show that poly (ethylacetylene carboxylate) has the potential for the use as optical limiting material for future applications. (author)

  13. Carbon nanotubes for gas detection: materials preparation and device assembly

    International Nuclear Information System (INIS)

    Terranova, M L; Lucci, M; Orlanducci, S; Tamburri, E; Sessa, V; Reale, A; Carlo, A Di

    2007-01-01

    An efficient sensing device for NH 3 and NO x detection has been realized using ordered arrays of single-walled C nanotubes deposited onto an interdigitated electrode platform operating at room temperature. The sensing material has been prepared using several chemical-physical techniques for purification and positioning of the nanotubes inside the electrode gaps. In particular, both DC and AC fields have been applied in order to move and to align the nanostructures by electrophoresis and dielectrophoresis processes. We investigated the effects of different voltages applied to a gate contact on the back side of the substrate on the performances of the device and found that for different gas species (NH 3 , NO x ) a constant gate bias increases the sensitivity for gas detection. Moreover, in this paper we demonstrate that a pulsed bias applied to the gate contact facilitates the gas interaction with the nanotubes, either reducing the absorption times or accelerating the desorption times, thus providing a fast acceleration and a dramatic improvement of the time dependent behaviour of the device

  14. Limits of detection in instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Guinn, V.P.

    1990-01-01

    Lower limits of detection (LLODs), frequently referred to simply as limits of detection and abbreviated as LODs, often appear in the literature of analytical chemistry - for numerous different methods of elemental and/or molecular analysis. In this chapter, one particular method of quantitative elemental analysis, that of instrumental neutron activation analysis (INAA), is the subject discussed, with reference to LODs. Particularly in the literature of neutron activation analysis (NAA), many tables of 'interference-free' NAA LODs are available. Not all of these are of much use, because (1) for many the definition used for LOD is not clear, or reasonable, (2) for many, the analysis conditions used are not clearly specified, and (3) for many, the analysis conditions used are specified, but not very practicable for most laboratories. For NAA work, such tables of interference-free LODs are, in any case, only applicable to samples in which, at the time of counting, only one radionuclide is present to any significant extent in the activated sample. It is important to note that tables of INAA LODs, per se, do not exist - since the LOD for a given element, under stated analysis conditions, can vary by orders of magnitude, depending on the elemental composition of the matrix in which it is present. For any given element, its INAA LOD will always be as large as, and usually much larger than, its tabulated 'interference-free' NAA LOD - how much larger depending upon the elemental composition of the matrix in which it is present. As discussed in this chapter, however, an INAA computer program exists that can calculate realistic INAA LODs for any elements of interest, in any kind of specified sample matrix, under any given set of analysis conditions

  15. TXRF 'measurements' of concentration distribution below the detection limit

    International Nuclear Information System (INIS)

    Kubala-Kukus, A.; Banas, D.; Braziewicz, J.; Majewska, U.; Mrowczynski, S.; Pajek, M.

    2000-01-01

    We demonstrate that a shape of the concentration distribution of the element in a set of samples, as measured by the TXRF method, can be determined even for the concentrations below the detection limit (DL). This can be done, when the measurements reporting the concentration below DL level are included properly in the analysis of the results. The method developed for such correction is presented and discussed. It is demonstrated that this correction is particularly important when the studied concentrations are close to the DL level of the method, which is a common case for TXRF. In the paper a precision of the developed correction is discussed in details, by using the results of numerical simulations of experiments for different concentration distributions and number of performed measurements. It is demonstrated that the factor, which limits the accuracy of the correction, is the number of measurements, not the correction procedure itself. The applicability and importance of the developed correction is demonstrated for routine TXRF analysis of different types of samples of bio-medical interest. (author)

  16. Physiological techniques for detecting expiratory flow limitation during tidal breathing

    Directory of Open Access Journals (Sweden)

    N.G. Koulouris

    2011-09-01

    Full Text Available Patients with severe chronic obstructive pulmonary disease (COPD often exhale along the same flow–volume curve during quiet breathing as they do during the forced expiratory vital capacity manoeuvre, and this has been taken as an indicator of expiratory flow limitation at rest (EFLT. Therefore, EFLT, namely attainment of maximal expiratory flow during tidal expiration, occurs when an increase in transpulmonary pressure causes no increase in expiratory flow. EFLT leads to small airway injury and promotes dynamic pulmonary hyperinflation, with concurrent dyspnoea and exercise limitation. In fact, EFLT occurs commonly in COPD patients (mainly in Global Initiative for Chronic Obstructive Lung Disease III and IV stage, in whom the latter symptoms are common, but is not exclusive to COPD, since it can also be detected in other pulmonary and nonpulmonary diseases like asthma, acute respiratory distress syndrome, heart failure and obesity, etc. The existing up to date physiological techniques of assessing EFLT are reviewed in the present work. Among the currently available techniques, the negative expiratory pressure has been validated in a wide variety of settings and disorders. Consequently, it should be regarded as a simple, noninvasive, practical and accurate new technique.

  17. Optimising Mycobacterium tuberculosis detection in resource limited settings.

    Science.gov (United States)

    Alfred, Nwofor; Lovette, Lawson; Aliyu, Gambo; Olusegun, Obasanya; Meshak, Panwal; Jilang, Tunkat; Iwakun, Mosunmola; Nnamdi, Emenyonu; Olubunmi, Onuoha; Dakum, Patrick; Abimiku, Alash'le

    2014-03-03

    The light-emitting diode (LED) fluorescence microscopy has made acid-fast bacilli (AFB) detection faster and efficient although its optimal performance in resource-limited settings is still being studied. We assessed the optimal performances of light and fluorescence microscopy in routine conditions of a resource-limited setting and evaluated the digestion time for sputum samples for maximum yield of positive cultures. Cross-sectional study. Facility-based involving samples of routine patients receiving tuberculosis treatment and care from the main tuberculosis case referral centre in northern Nigeria. The study included 450 sputum samples from 150 new patients with clinical diagnosis of pulmonary tuberculosis. The 450 samples were pooled into 150 specimens, examined independently with mercury vapour lamp (FM), LED CysCope (CY) and Primo Star iLED (PiLED) fluorescence microscopies, and with the Ziehl-Neelsen (ZN) microscopy to assess the performance of each technique compared with liquid culture. The cultured specimens were decontaminated with BD Mycoprep (4% NaOH-1% NLAC and 2.9% sodium citrate) for 10, 15 and 20 min before incubation in Mycobacterium growth incubator tube (MGIT) system and growth examined for acid-fast bacilli (AFB). Of the 150 specimens examined by direct microscopy: 44 (29%), 60 (40%), 49 (33%) and 64 (43%) were AFB positive by ZN, FM, CY and iLED microscopy, respectively. Digestion of sputum samples for 10, 15 and 20 min yielded mycobacterial growth in 72 (48%), 81 (54%) and 68 (45%) of the digested samples, respectively, after incubation in the MGIT system. In routine laboratory conditions of a resource-limited setting, our study has demonstrated the superiority of fluorescence microscopy over the conventional ZN technique. Digestion of sputum samples for 15 min yielded more positive cultures.

  18. Deterministic preparation of superpositions of vacuum plus one photon by adaptive homodyne detection: experimental considerations

    International Nuclear Information System (INIS)

    Pozza, Nicola Dalla; Wiseman, Howard M; Huntington, Elanor H

    2015-01-01

    The preparation stage of optical qubits is an essential task in all the experimental setups employed for the test and demonstration of quantum optics principles. We consider a deterministic protocol for the preparation of qubits as a superposition of vacuum and one photon number states, which has the advantage to reduce the amount of resources required via phase-sensitive measurements using a local oscillator (‘dyne detection’). We investigate the performances of the protocol using different phase measurement schemes: homodyne, heterodyne, and adaptive dyne detection (involving a feedback loop). First, we define a suitable figure of merit for the prepared state and we obtain an analytical expression for that in terms of the phase measurement considered. Further, we study limitations that the phase measurement can exhibit, such as delay or limited resources in the feedback strategy. Finally, we evaluate the figure of merit of the protocol for different mode-shapes handily available in an experimental setup. We show that even in the presence of such limitations simple feedback algorithms can perform surprisingly well, outperforming the protocols when simple homodyne or heterodyne schemes are employed. (paper)

  19. Bayesian-statistical decision threshold, detection limit, and confidence interval in nuclear radiation measurement

    International Nuclear Information System (INIS)

    Weise, K.

    1998-01-01

    When a contribution of a particular nuclear radiation is to be detected, for instance, a spectral line of interest for some purpose of radiation protection, and quantities and their uncertainties must be taken into account which, such as influence quantities, cannot be determined by repeated measurements or by counting nuclear radiation events, then conventional statistics of event frequencies is not sufficient for defining the decision threshold, the detection limit, and the limits of a confidence interval. These characteristic limits are therefore redefined on the basis of Bayesian statistics for a wider applicability and in such a way that the usual practice remains as far as possible unaffected. The principle of maximum entropy is applied to establish probability distributions from available information. Quantiles of these distributions are used for defining the characteristic limits. But such a distribution must not be interpreted as a distribution of event frequencies such as the Poisson distribution. It rather expresses the actual state of incomplete knowledge of a physical quantity. The different definitions and interpretations and their quantitative consequences are presented and discussed with two examples. The new approach provides a theoretical basis for the DIN 25482-10 standard presently in preparation for general applications of the characteristic limits. (orig.) [de

  20. Neutron activation analysis detection limits using 252Cf sources

    International Nuclear Information System (INIS)

    DiPrete, D.P.; Sigg, R.A.

    2000-01-01

    The Savannah River Technology Center (SRTC) developed a neutron activation analysis (NAA) facility several decades ago using low-flux 252 Cf neutron sources. Through this time, the facility has addressed areas of applied interest in managing the Savannah River Site (SRS). Some applications are unique because of the site's operating history and its chemical-processing facilities. Because sensitivity needs for many applications are not severe, they can be accomplished using an ∼6-mg 252 Cf NAA facility. The SRTC 252 Cf facility continues to support applied research programs at SRTC as well as other SRS programs for environmental and waste management customers. Samples analyzed by NAA include organic compounds, metal alloys, sediments, site process solutions, and many other materials. Numerous radiochemical analyses also rely on the facility for production of short-lived tracers, yielding by activation of carriers and small-scale isotope production for separation methods testing. These applications are more fully reviewed in Ref. 1. Although the flux [approximately2 x 10 7 n/cm 2 ·s] is low relative to reactor facilities, more than 40 elements can be detected at low and sub-part-per-million levels. Detection limits provided by the facility are adequate for many analytical projects. Other multielement analysis methods, particularly inductively coupled plasma atomic emission and inductively coupled plasma mass spectrometry, can now provide sensitivities on dissolved samples that are often better than those available by NAA using low-flux isotopic sources. Because NAA allows analysis of bulk samples, (a) it is a more cost-effective choice when its sensitivity is adequate than methods that require digestion and (b) it eliminates uncertainties that can be introduced by digestion processes

  1. Current limitations and challenges in nanowaste detection, characterisation and monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Part, Florian; Zecha, Gudrun [Department of Water-Atmosphere-Environment, University of Natural Resources and Life Sciences, Institute of Waste Management, Muthgasse 107, 1190 Vienna (Austria); Causon, Tim [Department of Chemistry, Division of Analytical Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna (Austria); Sinner, Eva-Kathrin [Department of Nanobiotechnology, Institute for Synthetic Bioarchitectures, University of Natural Resources and Life Sciences, Muthgasse 11/II, 1190 Vienna (Austria); Huber-Humer, Marion, E-mail: marion.huber-humer@boku.ac.at [Department of Water-Atmosphere-Environment, University of Natural Resources and Life Sciences, Institute of Waste Management, Muthgasse 107, 1190 Vienna (Austria)

    2015-09-15

    Highlights: • First review on detection of nanomaterials in complex waste samples. • Focus on nanoparticles in solid, liquid and gaseous waste samples. • Summary of current applicable methods for nanowaste detection and characterisation. • Limitations and challenges of characterisation of nanoparticles in waste. - Abstract: Engineered nanomaterials (ENMs) are already extensively used in diverse consumer products. Along the life cycle of a nano-enabled product, ENMs can be released and subsequently accumulate in the environment. Material flow models also indicate that a variety of ENMs may accumulate in waste streams. Therefore, a new type of waste, so-called nanowaste, is generated when end-of-life ENMs and nano-enabled products are disposed of. In terms of the precautionary principle, environmental monitoring of end-of-life ENMs is crucial to allow assessment of the potential impact of nanowaste on our ecosystem. Trace analysis and quantification of nanoparticulate species is very challenging because of the variety of ENM types that are used in products and low concentrations of nanowaste expected in complex environmental media. In the framework of this paper, challenges in nanowaste characterisation and appropriate analytical techniques which can be applied to nanowaste analysis are summarised. Recent case studies focussing on the characterisation of ENMs in waste streams are discussed. Most studies aim to investigate the fate of nanowaste during incineration, particularly considering aerosol measurements; whereas, detailed studies focusing on the potential release of nanowaste during waste recycling processes are currently not available. In terms of suitable analytical methods, separation techniques coupled to spectrometry-based methods are promising tools to detect nanowaste and determine particle size distribution in liquid waste samples. Standardised leaching protocols can be applied to generate soluble fractions stemming from solid wastes, while

  2. Combining Electrochemical Sensors with Miniaturized Sample Preparation for Rapid Detection in Clinical Samples

    Science.gov (United States)

    Bunyakul, Natinan; Baeumner, Antje J.

    2015-01-01

    Clinical analyses benefit world-wide from rapid and reliable diagnostics tests. New tests are sought with greatest demand not only for new analytes, but also to reduce costs, complexity and lengthy analysis times of current techniques. Among the myriad of possibilities available today to develop new test systems, amperometric biosensors are prominent players—best represented by the ubiquitous amperometric-based glucose sensors. Electrochemical approaches in general require little and often enough only simple hardware components, are rugged and yet provide low limits of detection. They thus offer many of the desirable attributes for point-of-care/point-of-need tests. This review focuses on investigating the important integration of sample preparation with (primarily electrochemical) biosensors. Sample clean up requirements, miniaturized sample preparation strategies, and their potential integration with sensors will be discussed, focusing on clinical sample analyses. PMID:25558994

  3. A highly flexible polymerization technique to prepare fluorescent nanospheres for trace ammonia detection

    International Nuclear Information System (INIS)

    Waich, K.; Sandholzer, M.; Mayr, T.; Slugovc, C.; Klimant, I.

    2010-01-01

    The preparation of pH-sensitive nanospheres by emulsion polymerization for the detection of trace levels of ammonia is described. A fluorescent, polymerizable xanthene dye was copolymerized with styrene, crosslinkers and further copolymers aimed at enhancing the sensitivity to obtain materials for sensing of ammonia. A half-seeded technique was used to obtain stable emulsions of the monomers which were cured to obtain nanospheres with covalently attached active components. The nanospheres were embedded in a silicon matrix and the sensor films obtained were investigated regarding their response to ammonia at concentrations between 25 and 1,000 ppb. Sensors containing polystyrene nanospheres crosslinked with divinylbenzene showed the best performance in ammonia measurements exhibiting detection limits (LODs) of less than 25 ppb ammonia.

  4. Preparation of Pd/Bacterial Cellulose Hybrid Nanofibers for Dopamine Detection

    Directory of Open Access Journals (Sweden)

    Dawei Li

    2016-05-01

    Full Text Available Palladium nanoparticle-bacterial cellulose (PdBC hybrid nanofibers were synthesized by in-situ chemical reduction method. The obtained PdBC nanofibers were characterized by a series of analytical techniques. The results revealed that Pd nanoparticles were evenly dispersed on the surfaces of BC nanofibers. Then, the as-prepared PdBC nanofibers were mixed with laccase (Lac and Nafion to obtain mixture suspension, which was further modified on electrode surface to construct novel biosensing platform. Finally, the prepared electrochemical biosensor was employed to detect dopamine. The analysis result was satisfactory, the sensor showed excellent electrocatalysis towards dopamine with high sensitivity (38.4 µA·mM−1, low detection limit (1.26 µM, and wide linear range (5–167 µM. Moreover, the biosensor also showed good repeatability, reproducibility, selectivity and stability and was successfully used in the detection of dopamine in human urine, thus providing a promising method for dopamine analysis in clinical application.

  5. Comparison of molecular imprinted particles prepared using precipitation polymerization in water and chloroform for fluorescent detection of nitroaromatics

    Energy Technology Data Exchange (ETDEWEB)

    Stringer, R. Cody, E-mail: rcsm84@mail.mizzou.edu [Department of Biological Engineering, University of Missouri, Columbia, MO (United States); Gangopadhyay, Shubhra, E-mail: gangopadhyays@missouri.edu [Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO (United States); Grant, Sheila A., E-mail: grantsa@missouri.edu [Department of Biological Engineering, University of Missouri, Columbia, MO (United States)

    2011-10-10

    Highlights: {yields} Imprinted polymers prepared using precipitation polymerization. {yields} Comparison of chloroform and water as polymerization solvent. {yields} Imprinted polymer doped with quantum dots for fluorescent sensor. {yields} Fluorescent imprinted polymer used to detect nitroaromatic explosives. {yields} Chloroform is ideal solvent for molecular imprinting of nitroaromatics. - Abstract: A comparative study was conducted to study the effects that two different polymerization solvents would have on the properties of imprinted polymer microparticles prepared using precipitation polymerization. Microparticles prepared in chloroform, which previous results indicated was the optimal solvent for molecular imprinting of nitroaromatic explosive compounds, were compared to water, which was hypothesized to decrease water swelling of the polymer and allow enhanced rebinding of aqueous template. The microparticles were characterized and were integrated into a fluorescence sensing mechanism for detection of nitroaromatic explosive compounds. The performance of the sensing mechanisms was compared to illustrate which polymerization solvent produced optimal imprinted polymer microparticles for detection of nitroaromatic molecules. Results indicated that the structures of microparticles synthesized in chloroform versus water varied greatly. Sensor performance studies showed that the microparticles prepared in chloroform had greater imprinting efficiency and higher template rebinding than those prepared in water. For detection of 2,4,6-trinitrotoluene, the chloroform-based fluorescent microparticles achieved a lower limit of detection of 0.1 {mu}M, as compared to 100 {mu}M for the water-based fluorescent microparticles. Detection limits for 2,4-dinitrotoluene, as well as time response studies, also demonstrated that the chloroform-based particles are more effective for detection of nitroaromatic compounds than water-based particles. These results illustrate that the

  6. Comparison of molecular imprinted particles prepared using precipitation polymerization in water and chloroform for fluorescent detection of nitroaromatics

    International Nuclear Information System (INIS)

    Stringer, R. Cody; Gangopadhyay, Shubhra; Grant, Sheila A.

    2011-01-01

    Highlights: → Imprinted polymers prepared using precipitation polymerization. → Comparison of chloroform and water as polymerization solvent. → Imprinted polymer doped with quantum dots for fluorescent sensor. → Fluorescent imprinted polymer used to detect nitroaromatic explosives. → Chloroform is ideal solvent for molecular imprinting of nitroaromatics. - Abstract: A comparative study was conducted to study the effects that two different polymerization solvents would have on the properties of imprinted polymer microparticles prepared using precipitation polymerization. Microparticles prepared in chloroform, which previous results indicated was the optimal solvent for molecular imprinting of nitroaromatic explosive compounds, were compared to water, which was hypothesized to decrease water swelling of the polymer and allow enhanced rebinding of aqueous template. The microparticles were characterized and were integrated into a fluorescence sensing mechanism for detection of nitroaromatic explosive compounds. The performance of the sensing mechanisms was compared to illustrate which polymerization solvent produced optimal imprinted polymer microparticles for detection of nitroaromatic molecules. Results indicated that the structures of microparticles synthesized in chloroform versus water varied greatly. Sensor performance studies showed that the microparticles prepared in chloroform had greater imprinting efficiency and higher template rebinding than those prepared in water. For detection of 2,4,6-trinitrotoluene, the chloroform-based fluorescent microparticles achieved a lower limit of detection of 0.1 μM, as compared to 100 μM for the water-based fluorescent microparticles. Detection limits for 2,4-dinitrotoluene, as well as time response studies, also demonstrated that the chloroform-based particles are more effective for detection of nitroaromatic compounds than water-based particles. These results illustrate that the enhanced chemical properties of

  7. Limited irrigation research and infrared thermometry for detecting water stress

    Science.gov (United States)

    The USDA-ARS Limited Irrigation Research Farm, located outside of Greeley Colorado, is an experiment evaluating management perspectives of limited irrigation water. An overview of the farm systems is shown, including drip irrigation systems, water budgeting, and experimental design, as well as preli...

  8. Determination of detection limits for a VPD ICPMS method of analysis; Determination des limites de detection d'une methode d'analyse VPD ICPMS

    Energy Technology Data Exchange (ETDEWEB)

    Badard, M.; Veillerot, M

    2007-07-01

    This training course report presents the different methods of detection and quantifying of metallic impurities in semiconductors. One of the most precise technique is the collection of metal impurities by vapor phase decomposition (VPD) followed by their analysis by ICPMS (inductively coupled plasma mass spectrometry). The study shows the importance of detection limits in the domain of chemical analysis and the way to determine them for the ICPMS analysis. The results found on detection limits are excellent. Even if the detection limits reached with ICPMS performed after manual or automatic VPD are much higher than detection limits of ICPMS alone, this method remains one of the most sensible for ultra-traces analysis. (J.S.)

  9. Grasp Preparation Improves Change Detection for Congruent Objects

    Science.gov (United States)

    Symes, Ed; Tucker, Mike; Ellis, Rob; Vainio, Lari; Ottoboni, Giovanni

    2008-01-01

    A series of experiments provided converging support for the hypothesis that action preparation biases selective attention to action-congruent object features. When visual transients are masked in so-called "change-blindness scenes," viewers are blind to substantial changes between 2 otherwise identical pictures that flick back and forth. The…

  10. Preparation of Graphene-Modified Acupuncture Needle and Its Application in Detecting Neurotransmitters

    Science.gov (United States)

    Tang, Lina; Du, Danxin; Yang, Fan; Liang, Zhong; Ning, Yong; Wang, Hua; Zhang, Guo-Jun

    2015-06-01

    We report a unique nanosensing platform by combining modern nanotechnology with traditional acupuncture needle to prepare graphene-modified acupuncture needle (G-AN), and using it for sensitive detection of neurotransmitters via electrochemistry. An electrochemical deposition method was employed to deposit Au nanoparticles (AuNPs) on the tip surface of the traditional acupuncture needle, while the other part of the needle was coated with insulation paste. Subsequently, the G-AN was obtained by cyclic voltammetry reduction of a graphene oxide solution on the surface of the AuNPs. To investigate the sensing property of the G-AN, pH dependence was measured by recording the open circuit potential in the various pH buffer solutions ranging from 2.0 to 10.0. What’s more, the G-AN was further used for detection of dopamine (DA) with a limit of detection of 0.24 μM. This novel G-AN exhibited a good sensitivity and selectivity, and could realize direct detection of DA in human serum.

  11. DETECTING ALIEN LIMIT CYCLES NEAR A HAMILTONIAN 2-SADDLE CYCLE

    OpenAIRE

    LUCA, Stijn; DUMORTIER, Freddy; Caubergh, M.; Roussarie, R.

    2009-01-01

    This paper aims at providing and example of a cubic Hamiltonian 2-saddle cycle that after bifurcation can give rise to an alien limit cycle; this is a limit cycle that is not controlled by a zero of the related Abelian integral. To guarantee the existence of an alien limit cycle one can verify generic conditions on the Abelian integral and on the transition map associated to the connections of the 2-saddle cycle. In this paper, a general method is developed to compute the first and second der...

  12. Detection limits of intraoperative near infrared imaging for tumor resection.

    Science.gov (United States)

    Thurber, Greg M; Figueiredo, Jose-Luiz; Weissleder, Ralph

    2010-12-01

    The application of fluorescent molecular imaging to surgical oncology is a developing field with the potential to reduce morbidity and mortality. However, the detection thresholds and other requirements for successful intervention remain poorly understood. Here we modeled and experimentally validated depth and size of detection of tumor deposits, trade-offs in coverage and resolution of areas of interest, and required pharmacokinetics of probes based on differing levels of tumor target presentation. Three orthotopic tumor models were imaged by widefield epifluorescence and confocal microscopes, and the experimental results were compared with pharmacokinetic models and light scattering simulations to determine detection thresholds. Widefield epifluorescence imaging can provide sufficient contrast to visualize tumor margins and detect tumor deposits 3-5  mm deep based on labeled monoclonal antibodies at low objective magnification. At higher magnification, surface tumor deposits at cellular resolution are detectable at TBR ratios achieved with highly expressed antigens. A widefield illumination system with the capability for macroscopic surveying and microscopic imaging provides the greatest utility for varying surgical goals. These results have implications for system and agent designs, which ultimately should aid complete resection in most surgical beds and provide real-time feedback to obtain clean margins. © 2010 Wiley-Liss, Inc.

  13. Physics of detecting torsion and placing limits on its effects

    International Nuclear Information System (INIS)

    Stoeger, W.R.

    1985-01-01

    The essential principles of torsion-detection physics are presented, and an evaluation is conducted of several conceivable types of experiments and observations for actually detecting torsion fields, reemphasizing also the evident impossibility of successfully searching for its manifestations among cosmological relics. In particular, a polarized body, with net intrinsic (fundamental-particle) spin, is essential for detecting a torsion field. One which possesses only orbital angular momentum - rotation - or an unpolarized intrinsic spin density will not feel torsion. The fundamental problem in searching for such fields is the extremely small basic unit of the coupling or interaction energy between the torsion field and spin. The best way of maximizing the total interaction energy is to increase the spin density of the source sigma-s and at the same time the spin number SD of the detector. 15 references

  14. CT colonography with limited bowel preparation: prospective assessment of patient experience and preference in comparison to optical colonoscopy with cathartic bowel preparation

    International Nuclear Information System (INIS)

    Jensch, Sebastiaan; Bipat, Shandra; Vries, Ayso H. de; Heutinck, Anneke; Stoker, Jaap; Peringa, Jan; Montauban van Swijndregt, Alexander D.; Dekker, Evelien; Baak, Lubbertus C.

    2010-01-01

    The purpose of this study was to prospectively compare participant experience and preference of limited preparation computed tomography colonography (CTC) with full-preparation colonoscopy in a consecutive series of patients at increased risk of colorectal cancer. CTC preparation comprised 180 ml diatrizoate meglumine, 80 ml barium and 30 mg bisacodyl. For the colonoscopy preparation 4 l of polyethylene glycol solution was used. Participants' experience and preference were compared using the Wilcoxon signed rank test and the chi-squared test, respectively. Associations between preference and experience parameters for the 173 participants were determined by logistic regression. Diarrhoea occurred in 94% of participants during CTC preparation. This side effect was perceived as severely or extremely burdensome by 29%. Nonetheless, the total burden was significantly lower for the CTC preparation than for colonoscopy (9% rated the CTC preparation as severely or extremely burdensome compared with 59% for colonoscopy; p<0.001). Participants experienced significantly more pain, discomfort and total burden with the colonoscopy procedure than with CTC (p<0.001). After 5 weeks, 69% preferred CTC, 8% were indifferent and 23% preferred colonoscopy (p<0.001). A burdensome colonoscopy preparation and pain at colonoscopy were associated with CTC preference (p<0.04). In conclusion, participants' experience and preference were rated in favour of CTC with limited bowel preparation compared with full-preparation colonoscopy. (orig.)

  15. Importance of the lower limit of detection in radiological safety; Importancia del limite inferior de deteccion en seguridad radiologica

    Energy Technology Data Exchange (ETDEWEB)

    Rafael, Terol T; Hermenegildo, Maldonado M [Comision Nacional de Seguridad Nuclear y Salvaguardias (Mexico)

    1991-07-01

    The concept of the Lower Limit of Detection (LLD) it contributes in the solution of some problems related with the radiological safety, such as the realization of the tests of flight of the sealed radioactive sources; the determination of radioisotopes in environmental samples; the estimate of present radionuclides in polluted foods; in general, the detection of small quantities of radioactive materials present in materials of use or consumption by part of the man in his daily life; as the one Lower Limit of Detection is related with topics of statistics, in this work a small review of them is made, it was superficially discussed the mensuration problems related with the establishment of the Lower Limit of Detection.

  16. Detection Limits Of The 125I Air Sampler ''RIS125''

    International Nuclear Information System (INIS)

    Belaish, I.; Levinson, S.; German, U.; Kravchik, T.

    1999-01-01

    A system for 125 I monitoring in air (RIS-125) was designed and manufactured at NRCN. The main features of the system are described elsewhere. The system can monitor 125 I air contamination in gaseous and aerosol forms. An air monitoring system should have a fast response and the lowest available Minimum Detectable Activity (MDA). The present work presents the characteristic MDA values of the system

  17. Evaluation of uncertainty and detection limits in radioactivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Herranz, M. [Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, Escuela Tecnica Superior de Ingenieria de Bilbao, Alda. Urquijo, s/n, 48013 Bilbao (Spain); Idoeta, R. [Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, Escuela Tecnica Superior de Ingenieria de Bilbao, Alda. Urquijo, s/n, 48013 Bilbao (Spain)], E-mail: raquel.idoeta@ehu.es; Legarda, F. [Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, Escuela Tecnica Superior de Ingenieria de Bilbao, Alda. Urquijo, s/n, 48013 Bilbao (Spain)

    2008-10-01

    The uncertainty associated with the assessment of the radioactive content of any sample depends on the net counting rate registered during the measuring process and on the different weighting factors needed to transform this counting rate into activity, activity per unit mass or activity concentration. This work analyses the standard uncertainties in these weighting factors as well as their contribution to the uncertainty in the activity reported for three typical determinations for environmental radioactivity measurements in the laboratory. It also studies the corresponding characteristic limits and their dependence on the standard uncertainty related to those weighting factors, offering an analysis of the effectiveness of the simplified characteristic limits as evaluated by various measuring software and laboratories.

  18. Evaluation of uncertainty and detection limits in radioactivity measurements

    International Nuclear Information System (INIS)

    Herranz, M.; Idoeta, R.; Legarda, F.

    2008-01-01

    The uncertainty associated with the assessment of the radioactive content of any sample depends on the net counting rate registered during the measuring process and on the different weighting factors needed to transform this counting rate into activity, activity per unit mass or activity concentration. This work analyses the standard uncertainties in these weighting factors as well as their contribution to the uncertainty in the activity reported for three typical determinations for environmental radioactivity measurements in the laboratory. It also studies the corresponding characteristic limits and their dependence on the standard uncertainty related to those weighting factors, offering an analysis of the effectiveness of the simplified characteristic limits as evaluated by various measuring software and laboratories

  19. Miniaturized Sample Preparation and Rapid Detection of Arsenite in Contaminated Soil Using a Smartphone

    Directory of Open Access Journals (Sweden)

    Mohd Farhan Siddiqui

    2018-03-01

    Full Text Available Conventional methods for analyzing heavy metal contamination in soil and water generally require laboratory equipped instruments, complex procedures, skilled personnel and a significant amount of time. With the advancement in computing and multitasking performances, smartphone-based sensors potentially allow the transition of the laboratory-based analytical processes to field applicable, simple methods. In the present work, we demonstrate the novel miniaturized setup for simultaneous sample preparation and smartphone-based optical sensing of arsenic As(III in the contaminated soil. Colorimetric detection protocol utilizing aptamers, gold nanoparticles and NaCl have been optimized and tested on the PDMS-chip to obtain the high sensitivity with the limit of detection of 0.71 ppm (in the sample and a correlation coefficient of 0.98. The performance of the device is further demonstrated through the comparative analysis of arsenic-spiked soil samples with standard laboratory method, and a good agreement with a correlation coefficient of 0.9917 and the average difference of 0.37 ppm, are experimentally achieved. With the android application on the device to run the experiment, the whole process from sample preparation to detection is completed within 3 hours without the necessity of skilled personnel. The approximate cost of setup is estimated around 1 USD, weight 55 g. Therefore, the presented method offers the simple, rapid, portable and cost-effective means for onsite sensing of arsenic in soil. Combined with the geometric information inside the smartphones, the system will allow the monitoring of the contamination status of soils in a nation-wide manner.

  20. Miniaturized Sample Preparation and Rapid Detection of Arsenite in Contaminated Soil Using a Smartphone.

    Science.gov (United States)

    Siddiqui, Mohd Farhan; Kim, Soocheol; Jeon, Hyoil; Kim, Taeho; Joo, Chulmin; Park, Seungkyung

    2018-03-04

    Conventional methods for analyzing heavy metal contamination in soil and water generally require laboratory equipped instruments, complex procedures, skilled personnel and a significant amount of time. With the advancement in computing and multitasking performances, smartphone-based sensors potentially allow the transition of the laboratory-based analytical processes to field applicable, simple methods. In the present work, we demonstrate the novel miniaturized setup for simultaneous sample preparation and smartphone-based optical sensing of arsenic As(III) in the contaminated soil. Colorimetric detection protocol utilizing aptamers, gold nanoparticles and NaCl have been optimized and tested on the PDMS-chip to obtain the high sensitivity with the limit of detection of 0.71 ppm (in the sample) and a correlation coefficient of 0.98. The performance of the device is further demonstrated through the comparative analysis of arsenic-spiked soil samples with standard laboratory method, and a good agreement with a correlation coefficient of 0.9917 and the average difference of 0.37 ppm, are experimentally achieved. With the android application on the device to run the experiment, the whole process from sample preparation to detection is completed within 3 hours without the necessity of skilled personnel. The approximate cost of setup is estimated around 1 USD, weight 55 g. Therefore, the presented method offers the simple, rapid, portable and cost-effective means for onsite sensing of arsenic in soil. Combined with the geometric information inside the smartphones, the system will allow the monitoring of the contamination status of soils in a nation-wide manner.

  1. Limited scleroderma and early detection of visceral changes

    International Nuclear Information System (INIS)

    Kalyuzhnaya, L.D.; Potsibina, V.V.; Stychinskaya, L.P.; Turik, N.V.

    1989-01-01

    The state of liver, kidneys, osteoarticular apparatus at the early stages of development of limited scleroderma and with the exclusion of visceral changes on the basis of clinical-laboratory studies is investigated. 11 patients with scleroderma in the age of 7-18 years were examined. Osteoscintigraphy with 99m TC-phosphone and dynamic scintigraphy of kidneys without additional introduction of RF, and hepatocholecyctoscintigraphy with 99m tc-HIPA of the patients were realized. The conclusion is made that radionuclide investigation methods permit to reveal various visceral changes, which are not recognizable by clinical methods

  2. Methodologies for the practical determination and use of method detection limits

    International Nuclear Information System (INIS)

    Rucker, T.L.

    1995-01-01

    Method detection limits have often been misunderstood and misused. The basic definitions developed by Lloyd Currie and others have been combined with assumptions that are inappropriate for many types of radiochemical analyses. A partical way for determining detection limits based on Currie's basic definition is presented that removes the reliance on assumptions and that accounts for the total measurement uncertainty. Examples of proper and improper use of detection limits are also presented, including detection limits reported by commercial software for gamma spectroscopy and neutron activation analyses. (author) 6 refs.; 2 figs

  3. Practical low dose limits for passive personal dosemeters and the implications for uncertainties close to the limit of detection

    International Nuclear Information System (INIS)

    Gilvin, P. J.; Perks, C. A.

    2011-01-01

    Recent years have seen the increasing use of passive dosemeters that have high sensitivities and, in laboratory conditions, detection limits of <10 μSv. However, in real operational use the detection limits will be markedly higher, because a large fraction of the accrued dose will be due to natural background, and this must be subtracted in order to obtain the desired occupational dose. No matter how well known the natural background is, the measurement uncertainty on doses of a few tens of microsieverts will be large. Individual monitoring services need to recognise this and manage the expectations of their clients by providing sufficient information. (authors)

  4. Currie detection limits in gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    Geer, L.-E. de

    2004-01-01

    Currie Hypothesis testing is applied to gamma-ray spectral data, where an optimum part of the peak is used and the background is considered well known from nearby channels. With this, the risk of making Type I errors is about 100 times lower than commonly assumed. A programme, PeakMaker, produces random peaks with given characteristics on the screen and calculations are done to facilitate a full use of Poisson statistics in spectrum analyses. Short technical note summary: The Currie decision limit concept applied to spectral data is reinterpreted, which gives better consistency between the selected error risk and the observed error rates. A PeakMaker program is described and the few count problem is analyzed

  5. Current limitations and challenges in nanowaste detection, characterisation and monitoring.

    Science.gov (United States)

    Part, Florian; Zecha, Gudrun; Causon, Tim; Sinner, Eva-Kathrin; Huber-Humer, Marion

    2015-09-01

    Engineered nanomaterials (ENMs) are already extensively used in diverse consumer products. Along the life cycle of a nano-enabled product, ENMs can be released and subsequently accumulate in the environment. Material flow models also indicate that a variety of ENMs may accumulate in waste streams. Therefore, a new type of waste, so-called nanowaste, is generated when end-of-life ENMs and nano-enabled products are disposed of. In terms of the precautionary principle, environmental monitoring of end-of-life ENMs is crucial to allow assessment of the potential impact of nanowaste on our ecosystem. Trace analysis and quantification of nanoparticulate species is very challenging because of the variety of ENM types that are used in products and low concentrations of nanowaste expected in complex environmental media. In the framework of this paper, challenges in nanowaste characterisation and appropriate analytical techniques which can be applied to nanowaste analysis are summarised. Recent case studies focussing on the characterisation of ENMs in waste streams are discussed. Most studies aim to investigate the fate of nanowaste during incineration, particularly considering aerosol measurements; whereas, detailed studies focusing on the potential release of nanowaste during waste recycling processes are currently not available. In terms of suitable analytical methods, separation techniques coupled to spectrometry-based methods are promising tools to detect nanowaste and determine particle size distribution in liquid waste samples. Standardised leaching protocols can be applied to generate soluble fractions stemming from solid wastes, while micro- and ultrafiltration can be used to enrich nanoparticulate species. Imaging techniques combined with X-ray-based methods are powerful tools for determining particle size, morphology and screening elemental composition. However, quantification of nanowaste is currently hampered due to the problem to differentiate engineered from

  6. Colloidal silver nanoparticles prepared by UV-light induced citrate reduction technique for the quantitative detection of uric acid

    Science.gov (United States)

    Maity, Anupam; Panda, Sovan Kumar

    2018-04-01

    Reddish-yellow color colloid consisting of silver nanoparticles (Ag NPs) has been synthesized by reducing aqueous AgNO3 solution by photo-induced citrate reduction technique under UV light. As prepared colloid exhibits single and intense plasmonic absorption peak in the violet region of the visible spectra with the peak centered at 405 nm. The NPs are fine and spherical with diameter ranging from 5 to 10 nm. These colloidal NPs have been used for the quantitative detection of uric acid by UV-VIS spectroscopy. A linear red shifting of the characteristics Plasmonic absorption peak of Ag NPs is observed with uric acid concentration. Uric acid can be detected by UV-VIS spectroscopy down to 5 nM limit using the prepared colloid.

  7. Search times and probability of detection in time-limited search

    Science.gov (United States)

    Wilson, David; Devitt, Nicole; Maurer, Tana

    2005-05-01

    When modeling the search and target acquisition process, probability of detection as a function of time is important to war games and physical entity simulations. Recent US Army RDECOM CERDEC Night Vision and Electronics Sensor Directorate modeling of search and detection has focused on time-limited search. Developing the relationship between detection probability and time of search as a differential equation is explored. One of the parameters in the current formula for probability of detection in time-limited search corresponds to the mean time to detect in time-unlimited search. However, the mean time to detect in time-limited search is shorter than the mean time to detect in time-unlimited search and the relationship between them is a mathematical relationship between these two mean times. This simple relationship is derived.

  8. Determination of detection limits for a VPD ICPMS method of analysis

    International Nuclear Information System (INIS)

    Badard, M.; Veillerot, M.

    2007-01-01

    This training course report presents the different methods of detection and quantifying of metallic impurities in semiconductors. One of the most precise technique is the collection of metal impurities by vapor phase decomposition (VPD) followed by their analysis by ICPMS (inductively coupled plasma mass spectrometry). The study shows the importance of detection limits in the domain of chemical analysis and the way to determine them for the ICPMS analysis. The results found on detection limits are excellent. Even if the detection limits reached with ICPMS performed after manual or automatic VPD are much higher than detection limits of ICPMS alone, this method remains one of the most sensible for ultra-traces analysis. (J.S.)

  9. Improvement in Limit of Detection of Enzymatic Biogas Sensor Utilizing Chromatography Paper for Breath Analysis.

    Science.gov (United States)

    Motooka, Masanobu; Uno, Shigeyasu

    2018-02-02

    Breath analysis is considered to be an effective method for point-of-care diagnosis due to its noninvasiveness, quickness and simplicity. Gas sensors for breath analysis require detection of low-concentration substances. In this paper, we propose that reduction of the background current improves the limit of detection of enzymatic biogas sensors utilizing chromatography paper. After clarifying the cause of the background current, we reduced the background current by improving the fabrication process of the sensors utilizing paper. Finally, we evaluated the limit of detection of the sensor with the sample vapor of ethanol gas. The experiment showed about a 50% reduction of the limit of detection compared to previously-reported sensor. This result presents the possibility of the sensor being applied in diagnosis, such as for diabetes, by further lowering the limit of detection.

  10. Assessment of detection limits of fiber-optic distributed temperature sensing for detection of illicit connections

    NARCIS (Netherlands)

    Nienhuis, J.; De Haan, C.; Langeveld, J.G.; Klootwijk, M.; Clemens, F.H.L.R.

    2012-01-01

    Distributed Temperature Sensing (DTS) with fiber-optic cables is a powerful tool to detect illicit connections in storm sewer systems. High frequency temperature measurements along the in-sewer cable create a detailed representation of temperature anomalies due to illicit discharges. The detection

  11. Impact of sensor detection limits on protecting water distribution systems from contamination events

    International Nuclear Information System (INIS)

    McKenna, Sean Andrew; Hart, David Blaine; Yarrington, Lane

    2006-01-01

    Real-time water quality sensors are becoming commonplace in water distribution systems. However, field deployable, contaminant-specific sensors are still in the development stage. As development proceeds, the necessary operating parameters of these sensors must be determined to protect consumers from accidental and malevolent contamination events. This objective can be quantified in several different ways including minimization of: the time necessary to detect a contamination event, the population exposed to contaminated water, the extent of the contamination within the network, and others. We examine the ability of a sensor set to meet these objectives as a function of both the detection limit of the sensors and the number of sensors in the network. A moderately sized distribution network is used as an example and different sized sets of randomly placed sensors are considered. For each combination of a certain number of sensors and a detection limit, the mean values of the different objectives across multiple random sensor placements are calculated. The tradeoff between the necessary detection limit in a sensor and the number of sensors is evaluated. Results show that for the example problem examined here, a sensor detection limit of 0.01 of the average source concentration is adequate for maximum protection. Detection of events is dependent on the detection limit of the sensors, but for those events that are detected, the values of the performance measures are not a function of the sensor detection limit. The results of replacing a single sensor in a network with a sensor having a much lower detection limit show that while this replacement can improve results, the majority of the additional events detected had performance measures of relatively low consequence.

  12. Working with Detection Limits in X-Ray and Nuclear Spectrometry

    International Nuclear Information System (INIS)

    Van Espen, P.

    2003-01-01

    Full Text: Detection limits are important in many measurement procedures. Especially in analytical work we often need to take a decision about the presence or absence of a compound, or we need to guarantee that or instrument can detect the compound. Especially in regulatory work the concept of detection limits plays a crucial role. Data acquisition in x-ray and gamma-ray spectrometry is done by counting events for a preset time; hence the fluctuations in the observed spectra are governed by Poisson (counting) statistics. This makes the calculation of detection limits in principle very easy. However it is observed that there exists a great deal of confusion concerning the definition(s) and especially concerning the practical calculation and reporting of detection limits. In this contribution a simple but rigorous treatment of the concept of detection limits will be given, emphasizing on aspects such as a-priori and a-posterior i limits and on the effect of sample blank and instrumental blank in the calculation of the true detection limit. The problem of near zero background as observed in e.g. total reflection x-ray fluorescence analysis (T-XRF) and some low level counting applications will also be discussed. In this case Poisson statistics might not be applicable, affecting the decision limits with respect to the presence of absence of a signal. Finally handling data sets that contain detection limit values next to normal measured values, the so called problem of missing data will be discussed. Some suggestions to deal with this frequently occurring situation will be given

  13. Preparation of novel silver nanoplates/graphene composite and their application in vanillin electrochemical detection.

    Science.gov (United States)

    Huang, Linhong; Hou, Keyu; Jia, Xiao; Pan, Haibo; Du, Min

    2014-05-01

    Hexagonal Ag nanoplates (NPs) were synthesized by polyvinylpyrrolidone (PVP) and trisodium citrate (TSC) which selectively absorbed to Ag (100) and Ag (111) surfaces, then were anchored to graphene (GN) to form novel Ag NPs/GN composite. The thickness of Ag NPs is ~4 nm and the length is 18-66 nm. Transmission electron microscopy (TEM) image shows that the plates are f-c-c crystals containing {111} facets on their two planar surfaces. Zeta potential indicated that the surface of Ag NPs/GN is negatively charged while vanillin is positively charged. Thus Ag NPs/GN modified on glass carbon electrodes (GCE) allowed abundant adsorption for vanillin and electron transfer between vanillin and Ag NPs/GN/GCE. Square wave voltammetry (SWV) results indicated that the over potential on Ag NPs/GN/GCE negatively shifts 52 mV than that on Ag NPs/GCE. Ag NPs/GN with enhanced surface area and good conductivity exhibited an excellent electrocatalytic activity toward the oxidation of vanillin. The corresponding linear range was estimated to be from 2 to 100 μM (R(2)=0.998), and the detection limit is 3.32×10(-7) M (S/N=3). The as-prepared vanillin sensor exhibits good selectivity and potential application in practical vanillin determination. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Improved detection limits for phthalates by selective solid-phase micro-extraction

    KAUST Repository

    Zia, Asif I.; Afsarimanesh, Nasrin; Xie, Li; Nag, Anindya; Al-Bahadly, I. H.; Yu, P. L.; Kosel, Jü rgen

    2016-01-01

    Presented research reports on an improved method and enhanced limits of detection for phthalates; a hazardous additive used in the production of plastics by solid-phase micro-extraction (SPME) polymer in comparison to molecularly imprinted solid

  15. Limited interlaboratory comparison of Schmallenberg virus antibody detection in serum samples

    DEFF Research Database (Denmark)

    van der Poel, W. H. M.; Cay, B.; Zientara, S.

    2014-01-01

    Eight veterinary institutes in seven different countries in Europe participated in a limited interlaboratory comparison trial to evaluate laboratory performances of Schmallenberg virus (SBV) antibody detection in serum. Seven different sheep sera and three different cattle sera were circulated, a...

  16. Correction to the count-rate detection limit and sample/blank time-allocation methods

    International Nuclear Information System (INIS)

    Alvarez, Joseph L.

    2013-01-01

    A common form of count-rate detection limits contains a propagation of uncertainty error. This error originated in methods to minimize uncertainty in the subtraction of the blank counts from the gross sample counts by allocation of blank and sample counting times. Correct uncertainty propagation showed that the time allocation equations have no solution. This publication presents the correct form of count-rate detection limits. -- Highlights: •The paper demonstrated a proper method of propagating uncertainty of count rate differences. •The standard count-rate detection limits were in error. •Count-time allocation methods for minimum uncertainty were in error. •The paper presented the correct form of the count-rate detection limit. •The paper discussed the confusion between count-rate uncertainty and count uncertainty

  17. Errors detected in pediatric oral liquid medication doses prepared in an automated workflow management system.

    Science.gov (United States)

    Bledsoe, Sarah; Van Buskirk, Alex; Falconer, R James; Hollon, Andrew; Hoebing, Wendy; Jokic, Sladan

    2018-02-01

    The effectiveness of barcode-assisted medication preparation (BCMP) technology on detecting oral liquid dose preparation errors. From June 1, 2013, through May 31, 2014, a total of 178,344 oral doses were processed at Children's Mercy, a 301-bed pediatric hospital, through an automated workflow management system. Doses containing errors detected by the system's barcode scanning system or classified as rejected by the pharmacist were further reviewed. Errors intercepted by the barcode-scanning system were classified as (1) expired product, (2) incorrect drug, (3) incorrect concentration, and (4) technological error. Pharmacist-rejected doses were categorized into 6 categories based on the root cause of the preparation error: (1) expired product, (2) incorrect concentration, (3) incorrect drug, (4) incorrect volume, (5) preparation error, and (6) other. Of the 178,344 doses examined, 3,812 (2.1%) errors were detected by either the barcode-assisted scanning system (1.8%, n = 3,291) or a pharmacist (0.3%, n = 521). The 3,291 errors prevented by the barcode-assisted system were classified most commonly as technological error and incorrect drug, followed by incorrect concentration and expired product. Errors detected by pharmacists were also analyzed. These 521 errors were most often classified as incorrect volume, preparation error, expired product, other, incorrect drug, and incorrect concentration. BCMP technology detected errors in 1.8% of pediatric oral liquid medication doses prepared in an automated workflow management system, with errors being most commonly attributed to technological problems or incorrect drugs. Pharmacists rejected an additional 0.3% of studied doses. Copyright © 2018 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

  18. Minimum detection limit and spatial resolution of thin-sample field-emission electron probe microanalysis

    International Nuclear Information System (INIS)

    Kubo, Yugo; Hamada, Kotaro; Urano, Akira

    2013-01-01

    The minimum detection limit and spatial resolution for a thinned semiconductor sample were determined by electron probe microanalysis (EPMA) using a Schottky field emission (FE) electron gun and wavelength dispersive X-ray spectrometry. Comparison of the FE-EPMA results with those obtained using energy dispersive X-ray spectrometry in conjunction with scanning transmission electron microscopy, confirmed that FE-EPMA is largely superior in terms of detection sensitivity. Thin-sample FE-EPMA is demonstrated as a very effective method for high resolution, high sensitivity analysis in a laboratory environment because a high probe current and high signal-to-noise ratio can be achieved. - Highlights: • Minimum detection limit and spatial resolution determined for FE-EPMA. • Detection sensitivity of FE-EPMA greatly superior to that of STEM-EDX. • Minimum detection limit and spatial resolution controllable by probe current

  19. Effects of tissue-preparation-induced callose synthesis on estimates of plasmodesma size exclusion limits.

    Science.gov (United States)

    Radford, J E; White, R G

    2001-01-01

    Plasmodesmata are often characterised by their size exclusion limit (SEL), which is the molecular weight of the largest dye, introduced by microinjection, that will move from cell to cell. In this study, we investigated whether commonly used techniques for isolation and manipulation of tissues, and microinjection of fluorescent dyes, affected the SEL, and whether any such effects could be ameliorated by inhibiting callose deposition. We examined young root epidermal cells of Arabidopsis thaliana and staminal hair cells of Tradescantia virginiana, two tissues often used in experiments on symplastic transport. Transport in root tips dissected from the main plant body and in stamen hairs removed from the base of the stamen filament was compared with transport in undissected roots and stamen hairs attached to the base of the filament, respectively. Tissues were microinjected with fluorescent dyes (457 Da to > 3 kDa) with or without prior incubation in the callose deposition inhibitors 2-deoxy-D-glucose or aniline blue fluorochrome. In both tissues, dissection reduced the SEL, which was largely prevented by prior incubation in 2-deoxy-D-glucose but not by incubation in aniline blue fluorochrome. Thus, standard methods for tissue preparation can cause sufficient callose deposition to reduce cell-to-cell transport, and this needs to be considered in studies employing microinjection. Introduction of the dyes by pressure injection rather than iontophoresis decreased the SEL in A. thaliana but increased it in T. virginiana, showing that these two injection techniques do not necessarily give identical results and that plasmodesmata in different tissues may respond differently to similar experimental procedures.

  20. Censoring: a new approach for detection limits in total-reflection X-ray fluorescence

    International Nuclear Information System (INIS)

    Pajek, M.; Kubala-Kukus, A.; Braziewicz, J.

    2004-01-01

    It is shown that the detection limits in the total-reflection X-ray fluorescence (TXRF), which restrict quantification of very low concentrations of trace elements in the samples, can be accounted for using the statistical concept of censoring. We demonstrate that the incomplete TXRF measurements containing the so-called 'nondetects', i.e. the non-measured concentrations falling below the detection limits and represented by the estimated detection limit values, can be viewed as the left random-censored data, which can be further analyzed using the Kaplan-Meier (KM) method correcting for nondetects. Within this approach, which uses the Kaplan-Meier product-limit estimator to obtain the cumulative distribution function corrected for the nondetects, the mean value and median of the detection limit censored concentrations can be estimated in a non-parametric way. The Monte Carlo simulations performed show that the Kaplan-Meier approach yields highly accurate estimates for the mean and median concentrations, being within a few percent with respect to the simulated, uncensored data. This means that the uncertainties of KM estimated mean value and median are limited in fact only by the number of studied samples and not by the applied correction procedure for nondetects itself. On the other hand, it is observed that, in case when the concentration of a given element is not measured in all the samples, simple approaches to estimate a mean concentration value from the data yield erroneous, systematically biased results. The discussed random-left censoring approach was applied to analyze the TXRF detection-limit-censored concentration measurements of trace elements in biomedical samples. We emphasize that the Kaplan-Meier approach allows one to estimate the mean concentrations being substantially below the mean level of detection limits. Consequently, this approach gives a new access to lower the effective detection limits for TXRF method, which is of prime interest for

  1. Visualizing the Limits of Low Vision in Detecting Natural Image Features

    NARCIS (Netherlands)

    Hogervorst, M.A.; Damme, W.J.M. van

    2008-01-01

    Purpose. The purpose of our study was to develop a tool to visualize the limitations posed by visual impairments in detecting small and low-contrast elements in natural images. This visualization tool incorporates existing models of several aspects of visual perception, such as the band-limited

  2. Investigation of a gamma sensitive Ge-detector with Marinelligeometry. Determination of the detection limits

    International Nuclear Information System (INIS)

    Moricz, P.

    1984-01-01

    Different Marinelli geometries have been compared with a 180 ml standard plastic breaker geometry as a reference. The results show that the Marinelli geometries are the best. E.g. the detection limit with a Marinelli geometry of 0.5 l is only half compared with the limit when the standard geometry is used. (Edv)

  3. Potentials and Limitations of Real-Time Elastography for Prostate Cancer Detection: A Whole-Mount Step Section Analysis

    Directory of Open Access Journals (Sweden)

    Daniel Junker

    2012-01-01

    Full Text Available Objectives. To evaluate prostate cancer (PCa detection rates of real-time elastography (RTE in dependence of tumor size, tumor volume, localization and histological type. Materials and Methods. Thirdy-nine patients with biopsy proven PCa underwent RTE before radical prostatectomy (RPE to assess prostate tissue elasticity, and hard lesions were considered suspicious for PCa. After RPE, the prostates were prepared as whole-mount step sections and were compared with imaging findings for analyzing PCa detection rates. Results. RTE detected 6/62 cancer lesions with a maximum diameter of 0–5 mm (9.7%, 10/37 with a maximum diameter of 6–10 mm (27%, 24/34 with a maximum diameter of 11–20 20 mm (70.6%, 14/14 with a maximum diameter of >20 mm (100% and 40/48 with a volume ≥0.2 cm3 (83.3%. Regarding cancer lesions with a volume ≥ 0.2 cm³ there was a significant difference in PCa detection rates between Gleason scores with predominant Gleason pattern 3 compared to those with predominant Gleason pattern 4 or 5 (75% versus 100%; P=0.028. Conclusions. RTE is able to detect PCa of significant tumor volume and of predominant Gleason pattern 4 or 5 with high confidence, but is of limited value in the detection of small cancer lesions.

  4. Decreasing of the detection limit for gamma-ray Spectrometry with the influence of sample treatment

    International Nuclear Information System (INIS)

    Karami, M.; Sadighzadeh, A.; Asgharizadeh, F.; Sardari, D.; Tavassoli, A.; Arbabi, A.; Hochaghani, O.

    2009-01-01

    Full text: In this study the ash method has been applied for environmental sample treatment in order to decrease of the detection limit in gamma-ray spectrometry for low level radioactivity measurements. Detection limit in gamma ray spectrometry is the smallest expectation value of the net counting rate that can be detected on given probabilities. The environmental test samples have been changed into ash using a suitable oven. The heating were made under controlled temperature to avoid the escape of some radionuclides such as radiocaesium. The ash samples were measured by high resolution gamma-ray spectrometry system. (author)

  5. 78 FR 38024 - Magnolia LNG, LLC; Liquefied Natural Gas Limited; Notice of Intent To Prepare an Environmental...

    Science.gov (United States)

    2013-06-25

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PF13-9-000] Magnolia LNG, LLC; Liquefied Natural Gas Limited; Notice of Intent To Prepare an Environmental Impact Statement for the Planned Magnolia Liquefied Natural Gas Project, Request for Comments on Environmental Issues, and Notice of Public Scoping Meeting The staff of...

  6. Possibilities for decreasing detection limits of analytical methods for determination of transformation products of unsymmetrical dimethylhydrazine in environmental samples

    Directory of Open Access Journals (Sweden)

    Bulat Kenessov

    2015-12-01

    Full Text Available Most rockets of middle and heavy class launched from Kazakhstan, Russia, China and other countries still use highly toxic unsymmetrical dimethylhydrazine (UDMH as a liquid propellant. Study of migration, distribution and accumulation of UDMH transformation products in environment and human health impact assessment of space rocket activity are currently complicated due to the absence of analytical methods allowing detection of trace concentrations of these compounds in analyzed samples. This paper reviews methods and approaches, which can be applied for development of such methods. Detection limits at a part-per-trillion (ppt level may be achieved using most selective and sensitive methods based on gas or liquid chromatography in combination of tandem or high-resolution mass spectrometry. In addition, 1000-fold concentration of samples or integrated sample preparation methods, e.g., dynamic headspace extraction, are required. Special attention during development and application of such methods must be paid to purity of laboratory air, reagents, glassware and analytical instruments.

  7. Soy flour-derived carbon dots: facile preparation, fluorescence enhancement, and sensitive Fe{sup 3+} detection

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Liyang; Xu, Qian [China University of Petroleum, State Key Laboratory of Heavy Oil Processing (China); Zheng, Xing [Bei Jing Sinen En-Tech Co., Ltd (China); Zhang, Weina; Zheng, Jingtang, E-mail: jtzheng03@163.com; Wu, Mingbo, E-mail: wumb@upc.edu.cn; Wu, Wenting, E-mail: wuwt@upc.edu.cn [China University of Petroleum, State Key Laboratory of Heavy Oil Processing (China)

    2016-08-15

    Soy flour-derived carbon quantum dots (C-dots) were successfully synthesized via a facile one-step hydrothermal approach. The as-prepared C-dots exhibit an average diameter of 2.5 nm and the crystalline lattices are consistent with graphitic carbons. Meanwhile, they show strong photoluminescence (quantum yield is 7.85 %), good water solubility, and high photostability. Importantly, structural defects of the C-dots were designed to obtain controllable fluorescence, which was achieved by changing the contents of N defects and O defects of C-dots. Our results indicate that N defects can more effectively enhance the fluorescence emission than O defects. As the preparation temperature increases, the N defects are fine-tuned by substituting for partial O defects, reducing nonradiative recombination and enhancing fluorescence intensity, which is further confirmed by surface passivation. Due to its fine photostability, high sensitivity, and good selectivity for Fe{sup 3+}, the as-prepared C-dots were used as fluorescence probes for detection of ferric ion. The detection limitation comes to 0.021 µM.

  8. Preparation of genosensor for detection of specific DNA sequence of the hepatitis B virus

    International Nuclear Information System (INIS)

    Honorato Castro, Ana C.; França, Erick G.; Paula, Lucas F. de; Soares, Marcia M.C.N.; Goulart, Luiz R.; Madurro, João M.; Brito-Madurro, Ana G.

    2014-01-01

    Graphical abstract: - Highlights: • Specific oligonucleotide detection for hepatitis B based on poly-4-aminophenol matrix. • Electrochemical detection of the gene specific using ethidium bromide as indicator. • The detection limit was 2.61 nmol L −1 , with a correlation coefficient of 0.998 (n = 3). • The system discriminates three-base mismatches and non-complementary target. - Abstract: An electrochemical genosensor was constructed for detection of specific DNA sequence of the hepatitis B virus, based on graphite electrodes modified with poly(4-aminophenol) and incorporating a specific oligonucleotide probe. The modified electrode containing the probe was evaluated by differential pulse voltammetry, before and after incubation with the complementary oligonucleotide target. Detection was performed by monitoring oxidizable DNA bases (direct detection) or using ethidium bromide as indicator of the hybridization process (indirect detection). The device showed a detection limit for the oligonucleotide target of 2.61 nmol L −1 . Indirect detection using ethidium bromide was promising in discriminating mismatches, which is a very desirable attribute for detection of disease-related point mutations. In addition, it was possible to observe differences between hybridized and non-hybridized surfaces by atomic force microscopy

  9. Preparation of genosensor for detection of specific DNA sequence of the hepatitis B virus

    Energy Technology Data Exchange (ETDEWEB)

    Honorato Castro, Ana C.; França, Erick G. [Institute of Genetics and Biochemistry, Federal University of Uberlândia, Uberlândia (Brazil); Paula, Lucas F. de [Institute of Chemistry, Federal University of Uberlândia, Uberlândia (Brazil); Soares, Marcia M.C.N. [Adolfo Lutz Institute, Regional Laboratory in São José do Rio Preto (Brazil); Goulart, Luiz R. [Institute of Genetics and Biochemistry, Federal University of Uberlândia, Uberlândia (Brazil); Madurro, João M. [Institute of Chemistry, Federal University of Uberlândia, Uberlândia (Brazil); Brito-Madurro, Ana G., E-mail: agbrito@iqufu.ufu.br [Institute of Genetics and Biochemistry, Federal University of Uberlândia, Uberlândia (Brazil)

    2014-09-30

    Graphical abstract: - Highlights: • Specific oligonucleotide detection for hepatitis B based on poly-4-aminophenol matrix. • Electrochemical detection of the gene specific using ethidium bromide as indicator. • The detection limit was 2.61 nmol L{sup −1}, with a correlation coefficient of 0.998 (n = 3). • The system discriminates three-base mismatches and non-complementary target. - Abstract: An electrochemical genosensor was constructed for detection of specific DNA sequence of the hepatitis B virus, based on graphite electrodes modified with poly(4-aminophenol) and incorporating a specific oligonucleotide probe. The modified electrode containing the probe was evaluated by differential pulse voltammetry, before and after incubation with the complementary oligonucleotide target. Detection was performed by monitoring oxidizable DNA bases (direct detection) or using ethidium bromide as indicator of the hybridization process (indirect detection). The device showed a detection limit for the oligonucleotide target of 2.61 nmol L{sup −1}. Indirect detection using ethidium bromide was promising in discriminating mismatches, which is a very desirable attribute for detection of disease-related point mutations. In addition, it was possible to observe differences between hybridized and non-hybridized surfaces by atomic force microscopy.

  10. Preparation of genosensor for detection of specific DNA sequence of the hepatitis B virus

    Science.gov (United States)

    Honorato Castro, Ana C.; França, Erick G.; de Paula, Lucas F.; Soares, Marcia M. C. N.; Goulart, Luiz R.; Madurro, João M.; Brito-Madurro, Ana G.

    2014-09-01

    An electrochemical genosensor was constructed for detection of specific DNA sequence of the hepatitis B virus, based on graphite electrodes modified with poly(4-aminophenol) and incorporating a specific oligonucleotide probe. The modified electrode containing the probe was evaluated by differential pulse voltammetry, before and after incubation with the complementary oligonucleotide target. Detection was performed by monitoring oxidizable DNA bases (direct detection) or using ethidium bromide as indicator of the hybridization process (indirect detection). The device showed a detection limit for the oligonucleotide target of 2.61 nmol L-1. Indirect detection using ethidium bromide was promising in discriminating mismatches, which is a very desirable attribute for detection of disease-related point mutations. In addition, it was possible to observe differences between hybridized and non-hybridized surfaces by atomic force microscopy.

  11. Calculation of the detection limit in radiation measurements with systematic uncertainties

    International Nuclear Information System (INIS)

    Kirkpatrick, J.M.; Russ, W.; Venkataraman, R.; Young, B.M.

    2015-01-01

    The detection limit (L D ) or Minimum Detectable Activity (MDA) is an a priori evaluation of assay sensitivity intended to quantify the suitability of an instrument or measurement arrangement for the needs of a given application. Traditional approaches as pioneered by Currie rely on Gaussian approximations to yield simple, closed-form solutions, and neglect the effects of systematic uncertainties in the instrument calibration. These approximations are applicable over a wide range of applications, but are of limited use in low-count applications, when high confidence values are required, or when systematic uncertainties are significant. One proposed modification to the Currie formulation attempts account for systematic uncertainties within a Gaussian framework. We have previously shown that this approach results in an approximation formula that works best only for small values of the relative systematic uncertainty, for which the modification of Currie's method is the least necessary, and that it significantly overestimates the detection limit or gives infinite or otherwise non-physical results for larger systematic uncertainties where such a correction would be the most useful. We have developed an alternative approach for calculating detection limits based on realistic statistical modeling of the counting distributions which accurately represents statistical and systematic uncertainties. Instead of a closed form solution, numerical and iterative methods are used to evaluate the result. Accurate detection limits can be obtained by this method for the general case

  12. Censoring approach to the detection limits in X-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Pajek, M.; Kubala-Kukus, A.

    2004-01-01

    We demonstrate that the effect of detection limits in the X-ray fluorescence analysis (XRF), which limits the determination of very low concentrations of trace elements and results in appearance of the so-called 'nondetects', can be accounted for using the statistical concept of censoring. More precisely, the results of such measurements can be viewed as the left random censored data, which can further be analyzed using the Kaplan-Meier method correcting the data for the presence of nondetects. Using this approach, the results of measured, detection limit censored concentrations can be interpreted in a nonparametric manner including the correction for the nondetects, i.e. the measurements in which the concentrations were found to be below the actual detection limits. Moreover, using the Monte Carlo simulation technique we show that by using the Kaplan-Meier approach the corrected mean concentrations for a population of the samples can be estimated within a few percent uncertainties with respect of the simulated, uncensored data. This practically means that the final uncertainties of estimated mean values are limited in fact by the number of studied samples and not by the correction procedure itself. The discussed random-left censoring approach was applied to analyze the XRF detection-limit-censored concentration measurements of trace elements in biomedical samples

  13. Preparation of novel silver nanoplates/graphene composite and their application in vanillin electrochemical detection

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Linhong [Fujian Key Lab of Medical Instrument and Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Institute of Research for Functional Materials, Fuzhou University, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Hou, Keyu; Jia, Xiao [Institute of Research for Functional Materials, Fuzhou University, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Pan, Haibo, E-mail: hbpan@fzu.edu.cn [Fujian Key Lab of Medical Instrument and Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Institute of Research for Functional Materials, Fuzhou University, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Du, Min [Fujian Key Lab of Medical Instrument and Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2014-05-01

    Hexagonal Ag nanoplates (NPs) were synthesized by polyvinylpyrrolidone (PVP) and trisodium citrate (TSC) which selectively absorbed to Ag (100) and Ag (111) surfaces, then were anchored to graphene (GN) to form novel Ag NPs/GN composite. The thickness of Ag NPs is ∼ 4 nm and the length is 18–66 nm. Transmission electron microscopy (TEM) image shows that the plates are f-c-c crystals containing {111} facets on their two planar surfaces. Zeta potential indicated that the surface of Ag NPs/GN is negatively charged while vanillin is positively charged. Thus Ag NPs/GN modified on glass carbon electrodes (GCE) allowed abundant adsorption for vanillin and electron transfer between vanillin and Ag NPs/GN/GCE. Square wave voltammetry (SWV) results indicated that the over potential on Ag NPs/GN/GCE negatively shifts 52 mV than that on Ag NPs/GCE. Ag NPs/GN with enhanced surface area and good conductivity exhibited an excellent electrocatalytic activity toward the oxidation of vanillin. The corresponding linear range was estimated to be from 2 to 100 μM (R{sup 2} = 0.998), and the detection limit is 3.32 × 10{sup −7} M (S/N = 3). The as-prepared vanillin sensor exhibits good selectivity and potential application in practical vanillin determination. - Highlights: • Hexagonal Ag nanoplates were synthesized by controlling of PVP and trisodium citrate. • Ag nanoplates/GN composite allowed adsorption and electron transfer of vanillin. • The composite with good dispersion exhibits enhanced surface area and good catalysis. • Vanillin on the Ag NPs/GN/GCE shows high sensitivity and selectivity.

  14. Preparation of novel silver nanoplates/graphene composite and their application in vanillin electrochemical detection

    International Nuclear Information System (INIS)

    Huang, Linhong; Hou, Keyu; Jia, Xiao; Pan, Haibo; Du, Min

    2014-01-01

    Hexagonal Ag nanoplates (NPs) were synthesized by polyvinylpyrrolidone (PVP) and trisodium citrate (TSC) which selectively absorbed to Ag (100) and Ag (111) surfaces, then were anchored to graphene (GN) to form novel Ag NPs/GN composite. The thickness of Ag NPs is ∼ 4 nm and the length is 18–66 nm. Transmission electron microscopy (TEM) image shows that the plates are f-c-c crystals containing {111} facets on their two planar surfaces. Zeta potential indicated that the surface of Ag NPs/GN is negatively charged while vanillin is positively charged. Thus Ag NPs/GN modified on glass carbon electrodes (GCE) allowed abundant adsorption for vanillin and electron transfer between vanillin and Ag NPs/GN/GCE. Square wave voltammetry (SWV) results indicated that the over potential on Ag NPs/GN/GCE negatively shifts 52 mV than that on Ag NPs/GCE. Ag NPs/GN with enhanced surface area and good conductivity exhibited an excellent electrocatalytic activity toward the oxidation of vanillin. The corresponding linear range was estimated to be from 2 to 100 μM (R 2 = 0.998), and the detection limit is 3.32 × 10 −7 M (S/N = 3). The as-prepared vanillin sensor exhibits good selectivity and potential application in practical vanillin determination. - Highlights: • Hexagonal Ag nanoplates were synthesized by controlling of PVP and trisodium citrate. • Ag nanoplates/GN composite allowed adsorption and electron transfer of vanillin. • The composite with good dispersion exhibits enhanced surface area and good catalysis. • Vanillin on the Ag NPs/GN/GCE shows high sensitivity and selectivity

  15. The Culture of Family: How a Model Early Childhood Teacher Preparation Program Navigates a Limited Context

    Science.gov (United States)

    Nitecki, Elena

    2012-01-01

    This article examines an extraordinarily successful early childhood education teacher preparation program at an urban 2-year college struggling with retention. The Early Childhood Education Program in this case study is able to maintain a graduation rate that is over four times greater than that of the college average and has a reputation for…

  16. Prediction of the limit of detection of an optical resonant reflection biosensor.

    Science.gov (United States)

    Hong, Jongcheol; Kim, Kyung-Hyun; Shin, Jae-Heon; Huh, Chul; Sung, Gun Yong

    2007-07-09

    A prediction of the limit of detection of an optical resonant reflection biosensor is presented. An optical resonant reflection biosensor using a guided-mode resonance filter is one of the most promising label-free optical immunosensors due to a sharp reflectance peak and a high sensitivity to the changes of optical path length. We have simulated this type of biosensor using rigorous coupled wave theory to calculate the limit of detection of the thickness of the target protein layer. Theoretically, our biosensor has an estimated ability to detect thickness change approximately the size of typical antigen proteins. We have also investigated the effects of the absorption and divergence of the incident light on the detection ability of the biosensor.

  17. Theoretical detection limit of PIXE analysis using 20 MeV proton beams

    Science.gov (United States)

    Ishii, Keizo; Hitomi, Keitaro

    2018-02-01

    Particle-induced X-ray emission (PIXE) analysis is usually performed using proton beams with energies in the range 2∼3 MeV because at these energies, the detection limit is low. The detection limit of PIXE analysis depends on the X-ray production cross-section, the continuous background of the PIXE spectrum and the experimental parameters such as the beam currents and the solid angle and detector efficiency of X-ray detector. Though the continuous background increases as the projectile energy increases, the cross-section of the X-ray increases as well. Therefore, the detection limit of high energy proton PIXE is not expected to increase significantly. We calculated the cross sections of continuous X-rays produced in several bremsstrahlung processes and estimated the detection limit of a 20 MeV proton PIXE analysis by modelling the Compton tail of the γ-rays produced in the nuclear reactions, and the escape effect on the secondary electron bremsstrahlung. We found that the Compton tail does not affect the detection limit when a thin X-ray detector is used, but the secondary electron bremsstrahlung escape effect does have an impact. We also confirmed that the detection limit of the PIXE analysis, when used with 4 μm polyethylene backing film and an integrated beam current of 1 μC, is 0.4∼2.0 ppm for proton energies in the range 10∼30 MeV and elements with Z = 16-90. This result demonstrates the usefulness of several 10 MeV cyclotrons for performing PIXE analysis. Cyclotrons with these properties are currently installed in positron emission tomography (PET) centers.

  18. Recent advances in sample preparation techniques and methods of sulfonamides detection - A review.

    Science.gov (United States)

    Dmitrienko, Stanislava G; Kochuk, Elena V; Apyari, Vladimir V; Tolmacheva, Veronika V; Zolotov, Yury A

    2014-11-19

    Sulfonamides (SAs) have been the most widely used antimicrobial drugs for more than 70 years, and their residues in foodstuffs and environmental samples pose serious health hazards. For this reason, sensitive and specific methods for the quantification of these compounds in numerous matrices have been developed. This review intends to provide an updated overview of the recent trends over the past five years in sample preparation techniques and methods for detecting SAs. Examples of the sample preparation techniques, including liquid-liquid and solid-phase extraction, dispersive liquid-liquid microextraction and QuEChERS, are given. Different methods of detecting the SAs present in food and feed and in environmental, pharmaceutical and biological samples are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Preparation of miniantibodies to Azospirillum brasilense Sp245 surface antigens and their use for bacterial detection.

    Science.gov (United States)

    Dykman, Lev A; Staroverov, Sergei A; Guliy, Olga I; Ignatov, Oleg V; Fomin, Alexander S; Vidyasheva, Irina V; Karavaeva, Olga A; Bunin, Viktor D; Burygin, Gennady L

    2012-01-01

    This article reports the first preparation of miniantibodies to Azospirillum brasilense Sp245 surface antigens by using a combinatorial phage library of sheep antibodies. The prepared phage antibodies were used for the first time for lipopolysaccharide and flagellin detection by dot assay, electro-optical analysis of cell suspensions, and transmission electron microscopy. Interaction of A. brasilense Sp245 with antilipopolysaccharide and antiflagellin phage-displayed miniantibodies caused the magnitude of the electro-optical signal to change considerably. The electro-optical results were in good agreement with the electron microscopic data. This is the first reported possibility of employing phage-displayed miniantibodies in bacterial detection aided by electro-optical analysis of cell suspensions.

  20. Detection of radiation-induced hydrocarbons in baked sponge cake prepared with irradiated liquid egg

    International Nuclear Information System (INIS)

    Schulzki, G.; Spiegelberg, A.; Boegl, K.W.; Schreiber, G.A.

    1995-01-01

    For identification of irradiated food, radiation-induced volatile hydrocarbons (HC) are determined by gas chromatography in the non-polar fraction of fat. However, in complex food matrices the detection is often disturbed by fat-associated compounds. On-line coupling of high performance liquid chromatography (LC) and gas chromatography (GC) is very efficient to remove such compounds from the HC fraction. The high sensitivity of this fast and efficient technique is demonstrated by the example of detection of radiation-induced HC in fat isolated from baked sponge cake which had been prepared with irradiated liquid egg. (Author)

  1. Detection of radiation-induced hydrocarbons in baked sponged cake prepared with irradiated liquid egg

    Science.gov (United States)

    Schulzki, G.; Spiegelberg, A.; Bögl, K. W.; Schreiber, G. A.

    1995-02-01

    For identification of irradiated food, radiation-induced volatile hydrocarbons (HC) are determined by gas chromatography in the non-polar fraction of fat. However, in complex food matrices the detection is often disturbed by fat-associated compounds. On-line coupling of high performance liquid chromatography (LC) and gas chromatography (GC) is very efficient to remove such compounds from the HC fraction. The high sensitivity of this fast and efficient technique is demonstrated by the example of detection of radiation-induced HC in fat isolated from baked sponge cake which had been prepared with irradiated liquid egg.

  2. Application of Statistical Methods to Activation Analytical Results near the Limit of Detection

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Wanscher, B.

    1978-01-01

    Reporting actual numbers instead of upper limits for analytical results at or below the detection limit may produce reliable data when these numbers are subjected to appropriate statistical processing. Particularly in radiometric methods, such as activation analysis, where individual standard...... deviations of analytical results may be estimated, improved discrimination may be based on the Analysis of Precision. Actual experimental results from a study of the concentrations of arsenic in human skin demonstrate the power of this principle....

  3. Discuss the technology for decrease the detection limit of NaI(Tl) gamma spectrometer

    International Nuclear Information System (INIS)

    Guo Xiaobin; Qu Guopu; Liu Zhiying; Wang Hongyan; Wang Lieming

    2011-01-01

    The radioelement species is complex and quantity is few after nuclear explosion, thus it is hard to tell the difference when using the Nal (TI) Gamma spectrometer detection due to several kinds of the peak of nuclide overlapped in the scattering region. So there is a high demand for spectrometer stability, energy resolution, solution spectrum and minimum detective activity. The paper analysed the influenced factors to Nal (TI) Gamma spectrometer and the measures of detection limit decrease by experiments and MCNP simulation, which proposed the methods to reduce background through shielding in order to improve minimum detective activity. The experiment shows that choosing reasonable shielding can reduce the background effectively and improve the spectrometer low level radioactive detect ability. (authors)

  4. Sandwiched gold/PNIPAm/gold microstructures for smart plasmonics application: towards the high detection limit and Raman quantitative measurements.

    Science.gov (United States)

    Elashnikov, R; Mares, D; Podzimek, T; Švorčík, V; Lyutakov, O

    2017-08-07

    A smart plasmonic sensor, comprising a layer of a stimuli-responsive polymer sandwiched between two gold layers, is reported. As a stimuli-responsive material, a monolayer of poly(N-isopropylacrylamide) (PNIPAm) crosslinked globules is used. A quasi-periodic structure of the top gold layer facilitates efficient excitation and serves as a support for plasmon excitation and propagation. The intermediate layer of PNIPAm efficiently entraps targeted molecules from solutions. The sensor structure was optimized for efficient light focusing in the "active" PNIPAm layer. The optimization was based on the time-resolved finite-element simulations, which take into account the thickness of gold layers, size of PNIPAm globules and Raman excitation wavelength (780 nm). The prepared structures were characterized using SEM, AFM, UV-Vis refractometry and goniometry. Additional AFM scans were performed in water at two temperatures corresponding to the collapsed and swollen PNIPAm states. The Raman measurements demonstrate a high detection limit and perfect reproducibility of the Raman scattering signal for the prepared sensor. In addition, the use of created SERS structures for the detection of relevant molecules in the medical, biological and safety fields was demonstrated.

  5. The detection limits of antimicrobial agents in cow's milk by a simple Yoghurt Culture Test.

    Science.gov (United States)

    Mohsenzadeh, M; Bahrainipour, A

    2008-09-15

    The aim of this study was to study performance of Yoghurt Culture Test (YCT) in the detection of antimicrobial residues in milk. For this purpose, the sensitivity of YCT for 15 antibiotics were determined. For each drug, 8 concentrations were tested. The detection limits of YCT at 2.5 h and 4 h incubation were determined (microg kg(-1)): 15 and 37.5, penicillin G; 4 and 5, ampicillin; 5 and 7.5, amoxycillin; 100 and 200, cephalexin; 80 and 100, cefazoline; 100 and 200, oxytetracycline; 500 and 100, chlortetracycline; 100 and 200, tetracycline; 150 and 200, doxycycline; 200 and 400, sulphadimidine; 500 and 1000, gentamycin; 1000 and 1500, spectinomycin; 400 and 500, erythromycin; 50 and 100, tylosin; 5000 and 10000, chloramphenicol. The YCT detection limits at 2.5 h incubation for ampicillin, cephalexin, tetracycline, oxytetracycline and tylosin are similar to those obtained as Maximum Residue Limit (MRL) according to Regulation 2377/90 EEC as set out by the European Union. In addition the detection limits of YCT for some antibiotics were lower than some of microbial inhibitor test.

  6. ROBUST ESTIMATION OF MEAN AND VARIANCE USING ENVIRONMENTAL DATA SETS WITH BELOW DETECTION LIMIT OBSERVATIONS

    Science.gov (United States)

    Scientists, especially environmental scientists often encounter trace level concentrations that are typically reported as less than a certain limit of detection, L. Type 1, left-censored data arise when certain low values lying below L are ignored or unknown as they cannot be mea...

  7. Detection limits of antimicrobials in ewe milk by delvotest photometric measurements.

    Science.gov (United States)

    Althaus, R L; Torres, A; Montero, A; Balasch, S; Molina, M P

    2003-02-01

    The Delvotest method detection limits per manufacturer's instructions at a fixed reading time of 3 h for 24 antimicrobial agents were determined in ewe milk by photometric measurement. For each drug, eight concentrations were tested on 20 ewe milk samples from individual ewes. Detection limits, determined by means of logistic regression models, were (microg/kg): 3, amoxycillin; 2, ampicillin; 18, cloxacillin; 1, penicillin "G"; 34, cefadroxil; 430, cephalosporin "C"; 40, cephalexin; 20, cefoperazone; 33, Ceftiofur; 18, cefuroxime; 6100, streptomycin; 1200, gentamycin; 2600, neomycin; 830, erythromycin; 100, tylosin; 180, doxycycline; 320, oxytetracycline; 590, tetracycline; 88, sulfadiazine; 44, sulfamethoxazole; 140, sulfametoxypyridazine; 48, sulfaquinoxaline; 12,000, chloramphenicol; and 290, trimethoprim. Whereas the beta-lactam antibiotics, sulphonamides, and tylosin were detected by Delvotest method at levels equal to those of maximum residue limits, its sensitivity needs to be enhanced to detect aminoglycosides, tetracyclines, streptomycin, chloramphenicol, and trimethoprim residues in ewe milk or to develop an integrated residue detection system for ewe milk with different sensitive microorganisms for each group of antiinfectious agents.

  8. Investigation on feasibility and detection limits for determination of coating film thickness by neutron activation analysis

    International Nuclear Information System (INIS)

    Yao Maoying; Xu Jiayun; Zhang Dida; Yang Zunyong; Yao Zhenqiang; Wang Mingqiu; Gao Dangzhong

    2010-01-01

    A method for the determination of coating film thickness by neutron activation was proposed in this paper. After Au, Al and Cu et al.films were activated with a Am-Be neutron source, the characteristic γ-rays emitted by the activated nuclides in the films were counted with a HPGe γ spectrometer. The detection limits of film thickness by using a nuclear reactor neutron source were deduced on the basis of the γ-ray counts and the Monte-Carlo simulated detection efficiencies. The possible detection limits are typically 4-5 orders of magnitude better than those by fluorescent X-ray method, which is currently widely used to determine coating film thickness. (authors)

  9. Aerosol quantification with the Aerodyne Aerosol Mass Spectrometer: detection limits and ionizer background effects

    Directory of Open Access Journals (Sweden)

    S. Borrmann

    2009-02-01

    Full Text Available Systematic laboratory experiments were performed to investigate quantification of various species with two versions of the Aerodyne Aerosol Mass Spectrometer, a Quadrupole Aerosol Mass Spectrometer (Q-AMS and a compact Time-of-Flight Aerosol Mass Spectrometer (c-ToF-AMS. Here we present a new method to continuously determine the detection limits of the AMS analyzers during regular measurements, yielding detection limit (DL information under various measurement conditions. Minimum detection limits range from 0.03 μg m−3 (nitrate, sulfate, and chloride up to 0.5 μg m−3 (organics for the Q-AMS. Those of the c-ToF-AMS are found between 0.003 μg m−3 (nitrate, sulfate and 0.03 μg m−3 (ammonium, organics. The DL values found for the c-ToF-AMS were ~10 times lower than those of the Q-AMS, mainly due to differences in ion duty cycle. Effects causing an increase of the detection limits include long-term instrument contamination, measurement of high aerosol mass concentrations and short-term instrument history. The self-cleaning processes which reduce the instrument background after measurement of large aerosol concentrations as well as the influences of increased instrument background on mass concentration measurements are discussed. Finally, improvement of detection limits by extension of averaging time intervals, selected or reduced ion monitoring, and variation of particle-to-background measurement ratio are investigated.

  10. Preparation of three-dimensionally ordered macroporous polycysteine film and application in sensitive detection of 4-chlorophenol

    International Nuclear Information System (INIS)

    Zhang, Shenghui; Shi, Zhen; Wang, Jinshou; Cheng, Qin; Wu, Kangbing

    2014-01-01

    Highlights: • Polycysteine film with three-dimensionally ordered porous structures was prepared. • 3-DOM polycysteine film exhibited large active area and signal enhancement effects. • 3-DOM polycysteine film increased oxidation signal of 4-chlorophenol by 5-fold. - Abstract: Polystyrene microspheres with diameter of 350 nm were prepared, and then used to arrange on the surface of glassy carbon electrode (GCE) as structure-directing template. By successive cyclic sweeps between −1.0 V and 2.0 V in pH 7 phosphate buffer containing 10 mM cysteine, polycysteine film was electrodeposited on polystyrene microspheres-arranged GCE. After removing polystyrene template, a three-dimensionally ordered macroporous (3-DOM) polycysteine film was achieved, as confirmed by scanning electron microscopy measurements. Electrochemical responses of K 3 [Fe(CN) 6 ] probe indicated that 3-DOM polycysteine film-modified GCE exhibited larger active area, compared with GCE, polycysteine film-modified GCE and electrochemically oxidized GCE. The application of 3-DOM polycysteine film in electrochemical detection of 4-chlorophenol was studied. Due to ordered porous structures, the 3-DOM polycysteine film-modified GCE displayed signal enhancement effects, and enhanced the oxidation peak currents of 4-chlorophenol. As a result, a sensitive electrochemical method was developed for the detection of 4-chlorophenol, and the detection limit was 1.67 × 10 −8 M. This new method was used to detect 4-chlorophenol in water samples, and the value of recovery was over the range from 99.6% to 107%

  11. Preparing Limited English Proficient Persons for the Workplace. ERIC Digest No. 215.

    Science.gov (United States)

    Wonacott, Michael E.

    This digest describes cultural considerations and effective approaches for limited English proficient (LEP) individuals' workforce development, including the impact of recent training legislation. LEP persons often come from both a different language background and a very different cultural background; so English-language instruction must provide…

  12. In vitro bioassays for detecting dioxin-like activity--application potentials and limits of detection, a review.

    Science.gov (United States)

    Eichbaum, Kathrin; Brinkmann, Markus; Buchinger, Sebastian; Reifferscheid, Georg; Hecker, Markus; Giesy, John P; Engwall, Magnus; van Bavel, Bert; Hollert, Henner

    2014-07-15

    Use of in vitro assays as screening tool to characterize contamination of a variety of environmental matrices has become an increasingly popular and powerful toolbox in the field of environmental toxicology. While bioassays cannot entirely substitute analytical methods such as gas chromatography-mass spectrometry (GC-MS), the increasing improvement of cell lines and standardization of bioassay procedures enhance their utility as bioanalytical pre-screening tests prior to more targeted chemical analytical investigations. Dioxin-receptor-based assays provide a holistic characterization of exposure to dioxin-like compounds (DLCs) by integrating their overall toxic potential, including potentials of unknown DLCs not detectable via e.g. GC-MS. Hence, they provide important additional information with respect to environmental risk assessment of DLCs. This review summarizes different in vitro bioassay applications for detection of DLCs and considers the comparability of bioassay and chemical analytically derived toxicity equivalents (TEQs) of different approaches and various matrices. These range from complex samples such as sediments through single reference to compound mixtures. A summary of bioassay derived detection limits (LODs) showed a number of current bioassays to be equally sensitive as chemical methodologies, but moreover revealed that most of the bioanalytical studies conducted to date did not report their LODs, which represents a limitation with regard to low potency samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Gold nanoparticle-based low limit of detection Love wave biosensor for carcinoembryonic antigens.

    Science.gov (United States)

    Li, Shuangming; Wan, Ying; Su, Yan; Fan, Chunhai; Bhethanabotla, Venkat R

    2017-09-15

    In this work, a Love wave biosensing platform is described for detecting cancer-related biomarker carcinoembryonic antigen (CEA). An ST 90°-X quartz Love wave device with a layer of SiO 2 waveguide was combined with gold nanoparticles (Au NPs) to amplify the mass loading effect of the acoustic wave sensor to achieve a limit of detection of 37pg/mL. The strategy involves modifying the Au NPs with anti-CEA antibody conjugates to form nanoprobes in a sandwich immunoassay. The unamplified detection limit of the Love wave biosensor is 9.4ng/mL. This 2-3 order of magnitude reduction in the limit of detection brings the SAW platform into the range useful for clinical diagnosis. Measurement electronics and microfluidics are easily constructed for acoustic wave biosensors, such as the Love wave device described here, allowing for robust platforms for point of care applications for cancer biomarkers in general. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Limits of 2D-TCA in detecting BOLD responses to epileptic activity.

    Science.gov (United States)

    Khatamian, Yasha Borna; Fahoum, Firas; Gotman, Jean

    2011-05-01

    Two-dimensional temporal clustering analysis (2D-TCA) is a relatively new functional MRI (fMRI) based technique that breaks blood oxygen level dependent activity into separate components based on timing and has shown potential for localizing epileptic activity independently of electroencephalography (EEG). 2D-TCA has only been applied to detect epileptic activity in a few studies and its limits in detecting activity of various forms (i.e. activation size, amplitude, and frequency) have not been investigated. This study evaluated 2D-TCA's ability to detect various forms of both simulated epileptic activity and EEG-fMRI activity detected in patients. When applied to simulated data, 2D-TCA consistently detected activity in 6min runs containing 5 spikes/run, 10 spikes/run, and one 5s long event with hemodynamic response function amplitudes of at least 1.5%, 1.25%, and 1% above baseline respectively. When applied to patient data, while detection of interictal spikes was inconsistent, 2D-TCA consistently produced results similar to those obtained by EEG-fMRI when at least 2 prolonged interictal events (a few seconds each) occurred during the run. However, even for such cases it was determined that 2D-TCA can only be used to validate localization by other means or to create hypotheses as to where activity may occur, as it also detects changes not caused by epileptic activity. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Method to Solve the Problem of the Radioactivity Detection in Environmental Samples. Characteristic Limits

    International Nuclear Information System (INIS)

    Gasco, C.; Martinez, M.; Heras, M.

    2009-01-01

    The problem of the detection or when the radioactivity can be considered as higher than the background using different measurement techniques has been the objective of several statistical studies and controversies. The detection limit and the critical limit were studied by Currie in year 1968 and used by radiochemistry laboratories considering different ways of calculation that introduced confusion and not correct implementations. In the last few years, and due to the increasing number of standardization processes on the field of radioactivity and accreditation, several international institutions have chosen to unify the criteria for using common determination of detection limits. The most used methods are those developed by MARLAP and International Standard Organization ISO (Standard-11929). In this report are summarised both standards doing a comparative study and giving some examples of how to apply these limits. In same cases, little differences in the uncertainty calculation have been observed but the final results have been concordant. A deeply study of these standards can be done consulting the web page of the American Labs that developed MARLAP or buying the original ISO standard ISO-11929 recently approved (2009). (Author) 17 refs

  16. The preparation of tourists to the ski sports tours in a limited time in order to prevent injuries and accidents

    Directory of Open Access Journals (Sweden)

    A.N. Toporkov

    2014-08-01

    Full Text Available Purpose: compare indicators of testing tourist skiers at different stages of the preparatory period to ski sports hike of third grade. Determine the effectiveness of training programs created to the tourists Categorical ski sports to prevent injuries and accidents in a limited time. Material: The study involved 13 people aged from 21 to 65 (4 women and 9 men with different experiences of hiking trails and various levels of total tourist preparedness. Results: The test results obtained before beginning the process of preparation are treated upon its completion, and immediately after passing categorical hike. In practice, the effectiveness of the proposed training programs of tourists to ski sports tours is proved. Conclusions : The created program can be recommended to tourist clubs, associations and organizations as the base in preparation for ski sports campaigns for the prevention of accidents and injuries.

  17. Detecting terrestrial nutrient limitation: a global meta-analysis of foliar nutrient concentrations after fertilization

    Directory of Open Access Journals (Sweden)

    Rebecca eOstertag

    2016-03-01

    Full Text Available Examining foliar nutrient concentrations after fertilization provides an alternative method for detecting nutrient limitation of ecosystems, which is logistically simpler to measure than biomass change. We present a meta-analysis of response ratios of foliar nitrogen and phosphorus (RRN, RRP after addition of fertilizer of nitrogen (N, phosphorus (P, or the two elements in combination, in relation to climate, ecosystem type, life form, family, and methodological factors. Results support other meta-analyses using biomass, and demonstrate there is strong evidence for nutrient limitation in natural communities. However, because N fertilization experiments greatly outnumber P fertilization trials, it is difficult to discern the absolute importance of N vs. P vs. co-limitation across ecosystems. Despite these caveats, it is striking that results did not follow conventional wisdom that temperate ecosystems are N-limited and tropical ones are P-limited. In addition, the use of ratios of N-to-P rather than response ratios also are a useful index of nutrient limitation, but due to large overlap in values, there are unlikely to be universal cutoff values for delimiting N vs. P limitation. Differences in RRN and RRP were most significant across ecosystem types, plant families, life forms, and between competitive environments, but not across climatic variables.

  18. Thermal ionization mass spectrometry (TIMS) of actinides: Pushing the limits of accuracy and detection

    Energy Technology Data Exchange (ETDEWEB)

    Buerger, Stefan; Boulyga, Sergei; Cunningham, Alan; Klose, Dilani; Koepf, Andreas; Poths, Jane [Safeguards Analytical Laboratory, International Atomic Energy Agency, Vienna (Austria); Richter, Stephan [Institute for Reference Materials and Measurements, JRC-EU, Geel (Belgium)

    2010-07-01

    New method developments in multi-collector thermal ionization mass spectrometry (MC-TIMS) for actinide isotope ratio analysis to improve accuracy and limits of detection will be presented. With respect to limits of detection, results on improving work function using various carbon additives will be reviewed and presented as well as developments in cavity ion source (as compared to standard flat ribbon filament ion source) for femto- and attogram levels of uranium, plutonium, and americium. With respect to accuracy, results on isotope ratio measurements of isotopes of uranium (relative accuracy of 0.3% to 0.01%) are presented with an example being U-234-Th-230 age-dating (NBL CRM 112-A). In this context, the importance of traceability (to the S.I. units) and the use of (certified) reference materials are emphasized. The focus of this presentation is on applications to nuclear safeguards / forensics.

  19. Flexible Modeling of Survival Data with Covariates Subject to Detection Limits via Multiple Imputation.

    Science.gov (United States)

    Bernhardt, Paul W; Wang, Huixia Judy; Zhang, Daowen

    2014-01-01

    Models for survival data generally assume that covariates are fully observed. However, in medical studies it is not uncommon for biomarkers to be censored at known detection limits. A computationally-efficient multiple imputation procedure for modeling survival data with covariates subject to detection limits is proposed. This procedure is developed in the context of an accelerated failure time model with a flexible seminonparametric error distribution. The consistency and asymptotic normality of the multiple imputation estimator are established and a consistent variance estimator is provided. An iterative version of the proposed multiple imputation algorithm that approximates the EM algorithm for maximum likelihood is also suggested. Simulation studies demonstrate that the proposed multiple imputation methods work well while alternative methods lead to estimates that are either biased or more variable. The proposed methods are applied to analyze the dataset from a recently-conducted GenIMS study.

  20. Preparation of gold nanoparticles-agarose gel composite and its application in SERS detection

    Science.gov (United States)

    Ma, Xiaoyuan; Xia, Yu; Ni, Lili; Song, Liangjing; Wang, Zhouping

    2014-03-01

    Agarose gel/gold nanoparticles hybrid was prepared by adding gold nanoparticles to preformed agarose gel. Nanocomposite structures and properties were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV-Vis-NIR absorption spectroscopy. Based on the swelling-contraction characteristics of agarose gel and the adjustable localized surface plasmon resonance (LSPR) of the gold nanoparticles, the nanocomposites were used as surface enhanced Raman scattering (SERS) substrate to detect the Raman signal molecules (NBA, MBA, 1NAT). Results revealed that the porous structure of the agarose gel provided a good carrier for the enrichment of the gold nanoparticles. The gold nanoparticles dynamic hot-spot effect arising from the agarose gel contraction loss of water in the air greatly enhanced the Raman signal. Furthermore, the gel could be cleaned with washing solution and recycling could be achieved for Raman detection.

  1. One-step preparation of silver–polyaniline nanotube composite for non-enzymatic hydrogen peroxide detection

    Energy Technology Data Exchange (ETDEWEB)

    Lorestani, Farnaz, E-mail: Farnaz.lorestani@siswa.um.edu.my; Shahnavaz, Zohreh; Nia, Pooria Moozarm; Alias, Y.; Manan, Ninie S.A., E-mail: niniemanan@um.edu.my

    2015-08-30

    Graphical abstract: - Highlights: • Silver nanoparticle-decorated polyaniline nanotube composites (AgNPs–PANINTs) have been fabricated through a one step modified method without adding any extra acids, template and surface modifier. • The sensor showed excellent selectivity, reproducibility, and stability properties. • The AgNPs–PANINTs composite that prepared with silver ammonia solution (Ag(NH{sub 3}){sub 2}OH) exhibits better electrochemical performance than the AgNPs–PANINTs composite that was prepared with silver nitrite (AgNO{sub 3}) due to smaller size and higher surface area of silver nanoparticle (AgNPs) in the composite. • The electrocatalytic activity for the reduction was strongly affected by the concentration of silver ammonia solution in the nanocomposites, with the best electrocatalytic activity observed for the composite of 6:1 volume ratios of PANI to Ag(NH{sub 3}){sub 2}OH (0.04 M). - Abstract: A modified glassy carbon electrode with silver nanoparticles–polyaniline nanotubes (AgNPs–PANINTs) composite is used as a non-enzymatic nanobiosensor for detecting hydrogen peroxide (H{sub 2}O{sub 2}). The electrocatalytic activity for the reduction was strongly affected by the concentration of silver ammonia solution in the nanocomposites, with the best electrocatalytic activity observed for the composite of 6:1 volume ratios of PANI to Ag(NH{sub 3}){sub 2}OH (0.04 M). Field emission scanning electron microscope images and their size distribution diagrams indicated that using the silver ammonia complex instead of silver nitrate caused uniform distribution of nanometer-sized silver nanoparticles with a narrow size distribution in the composite. The corresponding calibration curve for the current response showed a linear detection range of 0.1–90 mM (R{sup 2} = 0.9986), while the limit of detection was estimated to be 0.2 μM at the signal to noise ratio of 3.

  2. Detection limits of pollutants in water for PGNAA using Am-Be source

    International Nuclear Information System (INIS)

    Khelifi, R.; Amokrane, A.; Bode, P.

    2007-01-01

    A basic PGNAA facility with an Am-Be neutron source is described to analyze the pollutants in water. The properties of neutron flux were determined by MCNP calculations. In order to determine the efficiency curve of a HPGe detector, the prompt-gamma rays from chlorine were used and an exponential curve was fitted. The detection limits for typical water sample are also estimated using the statistical fluctuations of the background level in the areas of recorded the prompt-gamma spectrum

  3. Molecular techniques for detection and identification of pathogens in food: advantages and limitations

    OpenAIRE

    Palomino-Camargo, Carolina; Instituto de Ciencia y Tecnología de Alimentos, Facultad de Ciencias, Universidad Central de Venezuela. Caracas, Venezuela. Magíster en Ciencia y Tecnología de los Alimentos licenciada en Biología; González-Muñoz, Yuniesky; Instituto de Ciencia y Tecnología de Alimentos, Facultad de Ciencias, Universidad Central de Venezuela. Caracas, Venezuela. Ministerio del Poder Popular para la Alimentación. Caracas, Venezuela. licenciado en Ciencias de los Alimentos.

    2014-01-01

    Foodborne diseases, caused by pathogenic microorganisms, are a major public health problem worldwide. Microbiological methods commonly used in the detection of these foodborne pathogens are laborious and time consuming. This situation, coupled with the demand for immediate results and with technological advances, has led to the development of a wide range of rapid methods in recent decades. On this basis, this review describes the advantages and limitations of the main molecular methods used ...

  4. On the definition of the detection limit for non-selective determination of low activities

    International Nuclear Information System (INIS)

    Tschurlovits, M.

    1977-01-01

    Based on the latest published results, a detection limit which is easy to use in practical work without intensive consideration of counting statistics, is presented. The primary application of the given definition is the determination of gross activity. In the definition the error of the second kind as well as one-sided boundedness of the normal distribution are included. The results are given in graphical form. (orig.) [de

  5. The ground fault detection system for the Tore Supra toroidal pump limiter

    International Nuclear Information System (INIS)

    Zunino, K.; Cara, P.; Fejoz, P.; Hourtoule, J.; Loarer, T.; Pomaro, N.; Santagiustina, A.; Spuig, P.; Villecroze, F.

    2003-01-01

    The toroidal pump limiter (TPL) of Tore Supra is electrically insulated from the vacuum-vessel, to allow its polarization at a voltage of up to 1 kV. In order to monitor continuously the integrity of the TPL electrical insulation, an electronic diagnostic system called TPL ground fault detection system (GFDS) has been developed. The paper will report on the design and the operation experience of the GFD system and on the evolution of the TPL grounding

  6. Ion chromatographic analysis of high specific activity 18FDG preparations and detection of the chemical impurity 2-deoxy-2-chloro-D-glucose

    International Nuclear Information System (INIS)

    Alexoff, D.L.; Casati, R.; Fowler, J.S.; Wolf, A.P.; Shea, C.; Schlyer, D.J.; Chyng-Yann Shiue

    1992-01-01

    Because of the widespread use of 2-deoxy-2-[ 18 F]fluoro-D-glucose(FDG) prepared by the ''Julich'' method or its variants it was decided necessary to determine the major chemical impurities present in the final product. An analytical system for quantifying FDG was developed using pulsed amperometry after separation by high-performance anion exchange chromotography. With this system a heretofore unidentified impurity, 2-deoxy-2-chloro-D-glucose(C1DG) was found in our preparation and in those from other laboratories using the ''Julich'' method. C1DG arises from C1 - ion displacement during the labeling procedure where C1 - ion comes from several sources, and C1 - ion displacement from the HC1 used in the hydrolysis step. FDG mass was present in the same preparations at a level of ca 1-40 μg. Other major chemical constituents were glucose (ca 1-6 mg) and mannose (ca 10-18 μg). Glycerol, arising from sterilizing filters, was also detected in most preparations. Although C1DG is a chemical impurity which has not been detected previously in nca FDG preparations, its biochemical and pharmacological properties are similar to FDG and 2-deoxy-D-glucose. Thus it is unlikely that the presence of small quantities of C1DG found in typical FDG preparations (ca 100 μg) would have adverse pharmacological or toxicological consequences that would limit continued application of this radiopharmaceutical in basic and clinical studies. (Author)

  7. TransCanada PipeLines Limited 1996 annual report : profitable today, prepared for tomorrow

    International Nuclear Information System (INIS)

    1997-01-01

    Operations and financial activities of TransCanada PipeLines Limited (TPL) during 1996 were reviewed and made available for the benefit of shareholders. TransCanada PipeLines Limited is a Canadian company with assets in excess of $12 billion. Its pipeline system transports natural gas and crude oil from the Western Canada Sedimentary Basin to North America's major energy markets. By all accounts the company had a successful year in 1996, having delivered a record 2.4 Bcf of gas, up 3.7 per cent from 1995, through the Canadian Mainline, TransCanada's largest asset. Among other notable achievements was the decision to join the Portland Natural Gas Transmission System as a 20 per cent partner in a project to construct a natural gas pipeline between Quebec and Haverhill, Massachusetts. Another accomplishment was the completion of the acquisition of all remaining shares of Alberta Natural Gas company, thereby extending the company's energy transmission, gas processing and specialty chemical operations. Other achievements were the purchase of Enron Louisiana Energy Company, the acquisition of assets that position TPL as one of the largest natural gas liquids processors in North America and the completion and commissioning of two new independent power generation plants in Ontario. Shareholder's return on investment was 34 per cent, more than double the target of between 12 to 15 per cent. Net income to common shares amounted to $1.85 per share, up from $1.75 in 1995. The strong performance was attributed to continued growth in all four segments of TPL's business, i. e. energy transmission, energy marketing, energy processing and international. tabs., figs

  8. Evaluation on the detection limit of blood hemoglobin using photolepthysmography based on path-length optimization

    Science.gov (United States)

    Sun, Di; Guo, Chao; Zhang, Ziyang; Han, Tongshuai; Liu, Jin

    2016-10-01

    The blood hemoglobin concentration's (BHC) measurement using Photoplethysmography (PPG), which gets blood absorption to near infrared light from the instantaneous pulse of transmitted light intensity, has not been applied to the clinical use due to the non-enough precision. The main challenge might be caused of the non-enough stable pulse signal when it's very weak and it often varies in different human bodies or in the same body with different physiological states. We evaluated the detection limit of BHC using PPG as the measurement precision level, which can be considered as a best precision result because we got the relative stable subject's pulse signals recorded by using a spectrometer with high signal-to-noise ratio (SNR) level, which is about 30000:1 in short term. Moreover, we optimized the used pathlength using the theory based on optimum pathlength to get a better sensitivity to the absorption variation in blood. The best detection limit was evaluated as about 1 g/L for BHC, and the best SNR of pulse for in vivo measurement was about 2000:1 at 1130 and 1250 nm. Meanwhile, we conclude that the SNR of pulse signal should be better than 400:1 when the required detection limit is set to 5 g/L. Our result would be a good reference to the BHC measurement to get a desired BHC measurement precision of real application.

  9. Predictive inference for best linear combination of biomarkers subject to limits of detection.

    Science.gov (United States)

    Coolen-Maturi, Tahani

    2017-08-15

    Measuring the accuracy of diagnostic tests is crucial in many application areas including medicine, machine learning and credit scoring. The receiver operating characteristic (ROC) curve is a useful tool to assess the ability of a diagnostic test to discriminate between two classes or groups. In practice, multiple diagnostic tests or biomarkers are combined to improve diagnostic accuracy. Often, biomarker measurements are undetectable either below or above the so-called limits of detection (LoD). In this paper, nonparametric predictive inference (NPI) for best linear combination of two or more biomarkers subject to limits of detection is presented. NPI is a frequentist statistical method that is explicitly aimed at using few modelling assumptions, enabled through the use of lower and upper probabilities to quantify uncertainty. The NPI lower and upper bounds for the ROC curve subject to limits of detection are derived, where the objective function to maximize is the area under the ROC curve. In addition, the paper discusses the effect of restriction on the linear combination's coefficients on the analysis. Examples are provided to illustrate the proposed method. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  10. Detection and grading of dAVF: prospects and limitations of 3T MRI.

    Science.gov (United States)

    Bink, Andrea; Berkefeld, Joachim; Wagner, Marlies; You, Se-Jong; Ackermann, Hanns; Lorenz, Matthias W; Senft, Christian; du Mesnil de Rochemont, Richard

    2012-02-01

    DSA is currently the criterion standard for the assessment of dural arteriovenous fistulas (dAVF). Recently, evolving MRA techniques have emerged as a non-invasive alternative. The aim of this study is to assess the value of 3 T MRI in detecting and describing dAVF and to determine whether MRI can replace DSA as diagnostic procedure. A total of 19 patients with dAVF and 19 without dAVF underwent the same MRI protocol, including 3D time-of-flight MRA and time-resolved contrast-enhanced MRA. The images were evaluated retrospectively by three independent readers with different levels of experience blinded to clinical information. The readers assessed the presence, the site, the venous drainage and the feeders of dAVF. Sensitivity, specificity, accuracy, intertechnique and interobserver agreements were calculated. DAVF can be detected with high sensitivity, specificity and accuracy by experienced and also by less experienced readers. However, MRI has limitations when used for grading and evaluation of the angioarchitecture of the dAVF. Different experience, the limited resolution of MRI and its inability to selectively display arteries were the reasons for these limitations. With MRI dAVF can be detected reliably. Nevertheless, at present MRI can not fully replace DSA, especially for treatment planning.

  11. Detection limits for real-time source water monitoring using indigenous freshwater microalgae

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Jr, Miguel [ORNL; Greenbaum, Elias [ORNL

    2009-01-01

    This research identified toxin detection limits using the variable fluorescence of naturally occurring microalgae in source drinking water for five chemical toxins with different molecular structures and modes of toxicity. The five chemicals investigated were atrazine, Diuron, paraquat, methyl parathion, and potassium cyanide. Absolute threshold sensitivities of the algae for detection of the toxins in unmodified source drinking water were measured. Differential kinetics between the rate of action of the toxins and natural changes in algal physiology, such as diurnal photoinhibition, are significant enough that effects of the toxin can be detected and distinguished from the natural variance. This is true even for physiologically impaired algae where diminished photosynthetic capacity may arise from uncontrollable external factors such as nutrient starvation. Photoinhibition induced by high levels of solar radiation is a predictable and reversible phenomenon that can be dealt with using a period of dark adaption of 30 minutes or more.

  12. Preparation, Characterization, and UV Irradiation of Mars Soil Analogues Under Simulated Martian Conditions to Support Detection of Molecular Biomarkers

    Science.gov (United States)

    Fornaro, T.; Brucato, J. R.; ten Kate, I. L.; Siljeström, S.; Steele, A.; Cody, G. D.; Hazen, R. M.

    2018-04-01

    We present laboratory activities of preparation, characterization, and UV irradiation processing of Mars soil analogues, which are key to support both in situ exploration and sample return missions devoted to detection of molecular biomarkers on Mars.

  13. Preparation of a thin polysulfone phosphor sheet for the detection of alpha particles using adhesive process

    International Nuclear Information System (INIS)

    Seo, B. K.; Woo, Z. H.; Kim, G. H.; Chang, U. S.; Oh, W. Z.; Lee, K. W.; Han, M. J.

    2005-01-01

    According to atomic energy law and connection regs, the surface contamination of nuclear facilities should be monitored routinely. Surface contamination is divided into removable and fixed contamination. Fixed contamination is measured by a direct method with a survey meter. And removable contamination is measured by an indirect method using smear paper and a low background proportional counter. Also, in the decommissioning process of a nuclear research facilities, such as Korean Research Reactor 1 and 2 and Uranium Conversion Plant, a significant amount of nuclear wastes is produced. The wastes contaminated must be surveyed for the disposal and reuse in the future. In the previous study the medium, scintillatorembedded polymer membrane for detecting the alpharay, was prepared by impregnating organic scintillators in a membrane structure. The plastic scintillator consists of polysulfone(PSF) as a matrix with PPO as an organic scintillator and POPOP as a wave shifting agent dissolved in the matrix. But, an organic plastic scintillator was inadequate to detect the alpha particle in the alpha-beta mixing field because its light output is smaller than beta ray one. So, a thin phosphor sheet was prepared, which consisted of a very uniform deposit of silver activated zinc sulfide (ZnS(Ag)) phosphor applied to on side of clear polysulfone plastic sheet

  14. Preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles and their application in hydrogen peroxide detection

    International Nuclear Information System (INIS)

    Mahmoudian, M.R.; Alias, Y.; Basirun, W.J.; Ebadi, M.

    2012-01-01

    Highlights: ► Ag nanoparticles-decorated ultra thin polypyrrole nanosheets were prepared. ► Higher surface area of the polymer increased interaction between the polymer and Ag + . ► The sensitivity was estimated to be 4.477 μA mM −1 for linear segment. ► The LOD and LOQ (S/N = 3) were estimated to be 0.57 μM and 1.93 μM, respectively. - Abstract: This study examines the preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles (Ag-UTPNSs) and their application in the enzyme-less detection of hydrogen peroxide (H 2 O 2 ) detection. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results confirmed that Ag nanoparticles (NPs) were deposited onto the surface of the UTPNSs. The increase of the H 2 O 2 reduction current peak to 120 μA in the presence of the Ag-UTPNS/glassy carbon electrode (GCE) as compared to the UTPNS/GCE indicates that the sensitivity of the electrode to H 2 O 2 is significant. This observation can be explained by the larger surface area of the UTPNSs, which can increase the interactions between the polymer and the AgNO 3 solution during the deposition of the Ag NPs, and by the small size of the deposited Ag NPs, which can produce a surface area of Ag that is suitable for the reaction with H 2 O 2 . The amperometric responses show that the limit of detection, the limit of quantification (S/N = 3) and the sensitivity are estimated to be 0.57 μM, 1.93 μM and 4.477 μA mM −1 , respectively, for the linear segment. The results of the reproducibility experiments show that the use of Ag-UTPNS/GCE is feasible for the quantitative detection of certain concentration ranges of H 2 O 2 .

  15. Cytological preparations for molecular analysis: A review of technical procedures, advantages and limitations for referring samples for testing.

    Science.gov (United States)

    da Cunha Santos, G; Saieg, M A; Troncone, G; Zeppa, P

    2018-04-01

    Minimally invasive procedures such as endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) must yield not only good quality and quantity of material for morphological assessment, but also an adequate sample for analysis of molecular markers to guide patients to appropriate targeted therapies. In this context, cytopathologists worldwide should be familiar with minimum requirements for refereeing cytological samples for testing. The present manuscript is a review with comprehensive description of the content of the workshop entitled Cytological preparations for molecular analysis: pre-analytical issues for EBUS TBNA, presented at the 40th European Congress of Cytopathology in Liverpool, UK. The present review emphasises the advantages and limitations of different types of cytology substrates used for molecular analysis such as archival smears, liquid-based preparations, archival cytospin preparations and FTA (Flinders Technology Associates) cards, as well as their technical requirements/features. These various types of cytological specimens can be successfully used for an extensive array of molecular studies, but the quality and quantity of extracted nucleic acids rely directly on adequate pre-analytical assessment of those samples. In this setting, cytopathologists must not only be familiar with the different types of specimens and associated technical procedures, but also correctly handle the material provided by minimally invasive procedures, ensuring that there is sufficient amount of material for a precise diagnosis and correct management of the patient through personalised care. © 2018 John Wiley & Sons Ltd.

  16. How low can the detection limit go with VPD-TXRF

    International Nuclear Information System (INIS)

    Wang, J.; Balazs, M.; Pianetta, P.; Baur, K.; Brennan, S.; Boone, T.; Rosamilia, J.

    2000-01-01

    The detection limit for synchrotron radiation total reflection x-ray fluorescence (TXRF) that can routinely be achieved for transition metals is about 8E7 atoms/cm 2 for a standard 1000 second counting time. This high sensitivity can be further improved by using a pre-concentration process such as vapor phase decomposition (VPD). The sensitivity enhancement of VPD-TXRF over TXRF is usually estimated from the ratio of the total wafer surface area to the instrumental sampling area on the wafer. For example, a 200 mm wafer with a 5 mm edge exclusion has a total surface area of 283.5 cm 2 . Assuming a sampling area of 0.126 cm 2 for the TXRF instrument at the Stanford Synchrotron Radiation Laboratory (SSRL) the gain in sensitivity for the VPD-TXRF technique will be 1 : 2250. This means, theoretically, that the TXRF detection limit of 8E7 atoms/cm 2 could be further reduced to 3.6 E4 atoms/cm 2 by applying this technique. During the VPD process, the contaminants on the wafer surface will be collected into a single droplet and dried on the wafer surface for TXRF analysis. However, impurities in the UPW (ultra pure water), chemicals or from handling cannot be ignored. Our investigation of wafers subjected, to different cleaning processes has revealed that background signals on the dry spot could arise from the VPD process itself. Therefore, the baseline determined by the purity of the UPW and starting chemicals limits the detection limits of VPD-SR-TXRF. (author)

  17. Detection limits of Legionella pneumophila in environmental samples after co-culture with Acanthamoeba polyphaga

    Science.gov (United States)

    2013-01-01

    Background The efficiency of recovery and the detection limit of Legionella after co-culture with Acanthamoeba polyphaga are not known and so far no investigations have been carried out to determine the efficiency of the recovery of Legionella spp. by co-culture and compare it with that of conventional culturing methods. This study aimed to assess the detection limits of co-culture compared to culture for Legionella pneumophila in compost and air samples. Compost and air samples were spiked with known concentrations of L. pneumophila. Direct culturing and co-culture with amoebae were used in parallel to isolate L. pneumophila and recovery standard curves for both methods were produced for each sample. Results The co-culture proved to be more sensitive than the reference method, detecting 102-103 L. pneumophila cells in 1 g of spiked compost or 1 m3 of spiked air, as compared to 105-106 cells in 1 g of spiked compost and 1 m3 of spiked air. Conclusions Co-culture with amoebae is a useful, sensitive and reliable technique to enrich L. pneumophila in environmental samples that contain only low amounts of bacterial cells. PMID:23442526

  18. Including Below Detection Limit Samples in Post Decommissioning Soil Sample Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Hwan; Yim, Man Sung [KAIST, Daejeon (Korea, Republic of)

    2016-05-15

    To meet the required standards the site owner has to show that the soil at the facility has been sufficiently cleaned up. To do this one must know the contamination of the soil at the site prior to clean up. This involves sampling that soil to identify the degree of contamination. However there is a technical difficulty in determining how much decontamination should be done. The problem arises when measured samples are below the detection limit. Regulatory guidelines for site reuse after decommissioning are commonly challenged because the majority of the activity in the soil at or below the limit of detection. Using additional statistical analyses of contaminated soil after decommissioning is expected to have the following advantages: a better and more reliable probabilistic exposure assessment, better economics (lower project costs) and improved communication with the public. This research will develop an approach that defines an acceptable method for demonstrating compliance of decommissioned NPP sites and validates that compliance. Soil samples from NPP often contain censored data. Conventional methods for dealing with censored data sets are statistically biased and limited in their usefulness.

  19. Gravitational wave detection using laser interferometry beyond the standard quantum limit

    Science.gov (United States)

    Heurs, M.

    2018-05-01

    Interferometric gravitational wave detectors (such as advanced LIGO) employ high-power solid-state lasers to maximize their detection sensitivity and hence their reach into the universe. These sophisticated light sources are ultra-stabilized with regard to output power, emission frequency and beam geometry; this is crucial to obtain low detector noise. However, even when all laser noise is reduced as far as technically possible, unavoidable quantum noise of the laser still remains. This is a consequence of the Heisenberg Uncertainty Principle, the basis of quantum mechanics: in this case, it is fundamentally impossible to simultaneously reduce both the phase noise and the amplitude noise of a laser to arbitrarily low levels. This fact manifests in the detector noise budget as two distinct noise sources-photon shot noise and quantum radiation pressure noise-which together form a lower boundary for current-day gravitational wave detector sensitivities, the standard quantum limit of interferometry. To overcome this limit, various techniques are being proposed, among them different uses of non-classical light and alternative interferometer topologies. This article explains how quantum noise enters and manifests in an interferometric gravitational wave detector, and gives an overview of some of the schemes proposed to overcome this seemingly fundamental limitation, all aimed at the goal of higher gravitational wave event detection rates. This article is part of a discussion meeting issue `The promises of gravitational-wave astronomy'.

  20. The Impact of Including Below Detection Limit Samples in Post Decommissioning Soil Sample Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Hwan; Yim, Man-Sung [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    To meet the required standards the site owner has to show that the soil at the facility has been sufficiently cleaned up. To do this one must know the contamination of the soil at the site prior to clean up. This involves sampling that soil to identify the degree of contamination. However there is a technical difficulty in determining how much decontamination should be done. The problem arises when measured samples are below the detection limit. Regulatory guidelines for site reuse after decommissioning are commonly challenged because the majority of the activity in the soil at or below the limit of detection. Using additional statistical analyses of contaminated soil after decommissioning is expected to have the following advantages: a better and more reliable probabilistic exposure assessment, better economics (lower project costs) and improved communication with the public. This research will develop an approach that defines an acceptable method for demonstrating compliance of decommissioned NPP sites and validates that compliance. Soil samples from NPP often contain censored data. Conventional methods for dealing with censored data sets are statistically biased and limited in their usefulness. In this research, additional methods are performed using real data from a monazite manufacturing factory.

  1. Estimation of the limit of detection with a bootstrap-derived standard error by a partly non-parametric approach. Application to HPLC drug assays

    DEFF Research Database (Denmark)

    Linnet, Kristian

    2005-01-01

    Bootstrap, HPLC, limit of blank, limit of detection, non-parametric statistics, type I and II errors......Bootstrap, HPLC, limit of blank, limit of detection, non-parametric statistics, type I and II errors...

  2. Preparation of bioconjugates of CdTe nanocrystals for cancer marker detection

    International Nuclear Information System (INIS)

    Hu Fengqin; Ran Yuliang; Zhou Zhuan; Gao Mingyuan

    2006-01-01

    Highly fluorescent CdTe quantum dots (Q-dots) stabilized by 3-mercaptopropionic acid (MPA) were prepared by an aqueous solution approach and used as fluorescent labels in detecting a cancer marker, carcinoembryonic antigen (CEA), expressed on human colon carcinoma cell line LS 180. Nonspecific adsorptions of CdTe Q-dots on carcinoma cells were observed and effectively eliminated by replacing MPA with a thiolated PEG (poly(ethylene glycol), Mn = 750) synthesized according to literature. It was unexpectedly found out that the PEG-coated CdTe Q-dots exhibited very strong and specific affinity to anti-CEA monoclonal antibody rch 24 (rch 24 mAb). The resultant CdTe-(rch 24 mAb) conjugates were successfully used in detections of CEA expressed on the surface of cell line LS 180. Further experiments demonstrated that the fluorescent CdTe Q-dots exhibited much better photostability and a brighter fluorescence than FITC, which consequently led to a higher efficiency in the cancer marker detection

  3. Facile preparation of a DNA sensor for rapid herpes virus detection

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Phuong Dinh, E-mail: tampd-hast@mail.hut.edu.vn [Hanoi Advanced School of Science and Technology, Hanoi University of Technology (Viet Nam); Tuan, Mai Anh, E-mail: tuanma-itims@mail.hut.edu.vn [International Training Institute for Materials Science, Hanoi University of Technology (Viet Nam); Huy, Tran Quang [National Institute of Hygiene and Epidemiology (NIHE), 01 Yersin, Hai Ba Trung District, Hanoi (Viet Nam); Le, Anh-Tuan [Hanoi Advanced School of Science and Technology, Hanoi University of Technology (Viet Nam); Hieu, Nguyen Van, E-mail: hieu@itims.edu.vn [International Training Institute for Materials Science, Hanoi University of Technology (Viet Nam)

    2010-10-12

    In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from - 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane.

  4. Facile preparation of a DNA sensor for rapid herpes virus detection

    International Nuclear Information System (INIS)

    Tam, Phuong Dinh; Tuan, Mai Anh; Huy, Tran Quang; Le, Anh-Tuan; Hieu, Nguyen Van

    2010-01-01

    In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from - 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane.

  5. Novel Sample Preparation Method for Safe and Rapid Detection of Bacillus anthracis Spores in Environmental Powders and Nasal Swabs

    OpenAIRE

    Luna, Vicki A.; King, Debra; Davis, Carisa; Rycerz, Tony; Ewert, Matthew; Cannons, Andrew; Amuso, Philip; Cattani, Jacqueline

    2003-01-01

    Bacillus anthracis spores have been used as a biological weapon in the United States. We wanted to develop a safe, rapid method of sample preparation that provided safe DNA for the detection of spores in environmental and clinical specimens. Our method reproducibly detects B. anthracis in samples containing

  6. Estimation of the limit of detection in semiconductor gas sensors through linearized calibration models.

    Science.gov (United States)

    Burgués, Javier; Jiménez-Soto, Juan Manuel; Marco, Santiago

    2018-07-12

    The limit of detection (LOD) is a key figure of merit in chemical sensing. However, the estimation of this figure of merit is hindered by the non-linear calibration curve characteristic of semiconductor gas sensor technologies such as, metal oxide (MOX), gasFETs or thermoelectric sensors. Additionally, chemical sensors suffer from cross-sensitivities and temporal stability problems. The application of the International Union of Pure and Applied Chemistry (IUPAC) recommendations for univariate LOD estimation in non-linear semiconductor gas sensors is not straightforward due to the strong statistical requirements of the IUPAC methodology (linearity, homoscedasticity, normality). Here, we propose a methodological approach to LOD estimation through linearized calibration models. As an example, the methodology is applied to the detection of low concentrations of carbon monoxide using MOX gas sensors in a scenario where the main source of error is the presence of uncontrolled levels of humidity. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Radioactivity analyses and detection limit problems of environmental surveillance at a gas-cooled reactor

    International Nuclear Information System (INIS)

    Johnson, J.E.; Johnson, J.A.

    1988-01-01

    The lower limit of detection (LLD) values required by the USNRC for nuclear power facilities are often difficult to attain even using state of the art detection systems, e.g. the required LLD for I-131 in air is 70 fCi/m 3 . For a gas-cooled reactor where I-131 has never been observed in effluents, occasional false positive values occur due to: Counting statistics using high resolution Ge(Li) detectors, contamination from nuclear medicine releases and spectrum analysis systematic error. Statistically negative concentration values are often observed. These measurements must be included in the estimation of true mean values. For this and other reasons, the frequency distributions of this and other reasons, the frequency distributions of measured values appear to be log-normal. Difficulties in stating the true means and standard deviations are discussed for these situations

  8. Improved detection limit for {sup 59}Ni using the technique of accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Persson, Per; Erlandsson, Bengt; Hellborg, Ragnar; Kiisk, Madis; Larsson, Ragnar; Skog, Goeran; Stenstroem, Kristina [Lund Univ. (Sweden). Dept. of Nuclear Physics

    2002-11-01

    59 Ni is produced by neutron activation in the stainless steel close to the core of a nuclear reactor. To be able to classify the different parts of the reactor with respect to their content of long-lived radionuclides before final storage it is important to measure the 59 Ni level. Accelerator mass spectrometry is an ultra-sensitive method for counting atoms, suitable for 59 Ni measurements. Improvements in the reduction of the background and in the chemical reduction of cobalt, the interfering isobar, have been made. This chemical purification is essential when using small tandem accelerators, <3 MV, combined with the detection of characteristic projectile X-rays. These improvements have lowered the detection limit for 59 Ni by a factor of twenty compared with the first value reported for the Lund AMS facility. Material from the Swedish nuclear industry has been analysed and examples of the results are presented.

  9. Intrinsic spatial resolution limitations due to differences between positron emission position and annihilation detection localization

    International Nuclear Information System (INIS)

    Perez, Pedro; Malano, Francisco; Valente, Mauro

    2012-01-01

    Since its successful implementation for clinical diagnostic, positron emission tomography (PET) represents the most promising medical imaging technique. The recent major growth of PET imaging is mainly due to its ability to trace the biologic pathways of different compounds in the patient's body, assuming the patient can be labeled with some PET isotope. Regardless of the type of isotope, the PET imaging method is based on the detection of two 511-keV gamma photons being emitted in opposite directions, with almost 180 deg between them, as a consequence of electron-positron annihilation. Therefore, this imaging method is intrinsically limited by random uncertainties in spatial resolutions, related with differences between the actual position of positron emission and the location of the detected annihilation. This study presents an approach with the Monte Carlo method to analyze the influence of this effect on different isotopes of potential implementation in PET. (author)

  10. Diamond-based electrochemical aptasensor realizing a femtomolar detection limit of bisphenol A.

    Science.gov (United States)

    Ma, Yibo; Liu, Junsong; Li, Hongdong

    2017-06-15

    In this study, we designed and fabricated an electrochemical impedance aptasensor based on Au nanoparticles (Au-NPs) coated boron-doped diamond (BDD) modified with aptamers, and 6-mercapto-1-hexanol (MCH) for the detection of bisphenol A (BPA). The constructed BPA aptasensor exhibits good linearity from 1.0×10 -14 to 1.0×10 -9 molL -1 . The detection limitation of 7.2×10 -15 molL -1 was achieved, which can be attributed to the synergistic effect of combining BDD with Au-NPs, aptamers, and MCH. The examine results of BPA traces in Tris-HCl buffer and in milk, UV spectra of aptamer/BPA and interference test revealed that the novel aptasensors are of high sensitivity, specificity, stability and repeatability, which could be promising in practical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. New limits on the detection of a composition-dependent macroscopic force

    International Nuclear Information System (INIS)

    Boynton, P.; Aronson, S.

    1990-01-01

    We report here on a continuing experimental search for a macroscopic, composition dependent force coupling to ordinary matter. Within the phenomenological framework commonly employed -- a Yukawa representation of the interaction potential, and composition specified as some linear combination of baryon and lepton numbers -- the Index 3 experiment sets the most stringent upper limits yet on the interaction strength for coupling from B-2L to B-L, and for an interaction range from 200 m to 10 km. It is also the first null result to conflict with the marginal detection reported for the Index 1 experiment for all relevant values of the composition and range parameters

  12. Trace element analysis by EPMA in geosciences: detection limit, precision and accuracy

    Science.gov (United States)

    Batanova, V. G.; Sobolev, A. V.; Magnin, V.

    2018-01-01

    Use of the electron probe microanalyser (EPMA) for trace element analysis has increased over the last decade, mainly because of improved stability of spectrometers and the electron column when operated at high probe current; development of new large-area crystal monochromators and ultra-high count rate spectrometers; full integration of energy-dispersive / wavelength-dispersive X-ray spectrometry (EDS/WDS) signals; and the development of powerful software packages. For phases that are stable under a dense electron beam, the detection limit and precision can be decreased to the ppm level by using high acceleration voltage and beam current combined with long counting time. Data on 10 elements (Na, Al, P, Ca, Ti, Cr, Mn, Co, Ni, Zn) in olivine obtained on a JEOL JXA-8230 microprobe with tungsten filament show that the detection limit decreases proportionally to the square root of counting time and probe current. For all elements equal or heavier than phosphorus (Z = 15), the detection limit decreases with increasing accelerating voltage. The analytical precision for minor and trace elements analysed in olivine at 25 kV accelerating voltage and 900 nA beam current is 4 - 18 ppm (2 standard deviations of repeated measurements of the olivine reference sample) and is similar to the detection limit of corresponding elements. To analyse trace elements accurately requires careful estimation of background, and consideration of sample damage under the beam and secondary fluorescence from phase boundaries. The development and use of matrix reference samples with well-characterised trace elements of interest is important for monitoring and improving of the accuracy. An evaluation of the accuracy of trace element analyses in olivine has been made by comparing EPMA data for new reference samples with data obtained by different in-situ and bulk analytical methods in six different laboratories worldwide. For all elements, the measured concentrations in the olivine reference sample

  13. Picomolar detection limits with current-polarized Pb2+ ion-selective membranes.

    Science.gov (United States)

    Pergel, E; Gyurcsányi, R E; Tóth, K; Lindner, E

    2001-09-01

    Minor ion fluxes across ion-selective membranes bias submicromolar activity measurements with conventional ion-selective electrodes. When ion fluxes are balanced, the lower limit of detection is expected to be dramatically improved. As proof of principle, the flux of lead ions across an ETH 5435 ionophore-based lead-selective membrane was gradually compensated by applying a few nanoamperes of galvanostatic current. When the opposite ion fluxes were matched, and the undesirable leaching of primary ions was eliminated, Nernstian response down to 3 x 10(-12) M was achieved.

  14. Analysis of background components in Ge-spectrometry and their influence on detection limits

    Energy Technology Data Exchange (ETDEWEB)

    Heusser, G [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany)

    1997-03-01

    In low radioactivity measurements the system own background of the spectrometer is, besides the counting efficiency, the limiting factor for the achievable sensitivity. Since the latter is mostly fixed, background reduction is the only way to gain sensitivity, although it is inversely proportional only to the square root of the background rate but directly proportional to the counting efficiency. A thorough understanding of the background sources and their quantitative contribution helps to choose the most adequate suppression method in order to reach a certain required level of detection limit. For Ge-spectrometry the background can be reduced by 5 to 6 orders of magnitude compared to the unshielded case applying state-of-the-art techniques. This reduction factor holds for the continuous background spectrum as well as for the line background as demonstrated for a Ge detector of the Heidelberg-Moscow double beta decay experiment. (orig./DG)

  15. First direct detection limits on sub-GeV dark matter from XENON10.

    Science.gov (United States)

    Essig, Rouven; Manalaysay, Aaron; Mardon, Jeremy; Sorensen, Peter; Volansky, Tomer

    2012-07-13

    The first direct detection limits on dark matter in the MeV to GeV mass range are presented, using XENON10 data. Such light dark matter can scatter with electrons, causing ionization of atoms in a detector target material and leading to single- or few-electron events. We use 15  kg day of data acquired in 2006 to set limits on the dark-matter-electron scattering cross section. The strongest bound is obtained at 100 MeV where σ(e)dark-matter masses between 20 MeV and 1 GeV are bounded by σ(e)dark-matter candidates with masses well below the GeV scale.

  16. Power-limited low-thrust trajectory optimization with operation point detection

    Science.gov (United States)

    Chi, Zhemin; Li, Haiyang; Jiang, Fanghua; Li, Junfeng

    2018-06-01

    The power-limited solar electric propulsion system is considered more practical in mission design. An accurate mathematical model of the propulsion system, based on experimental data of the power generation system, is used in this paper. An indirect method is used to deal with the time-optimal and fuel-optimal control problems, in which the solar electric propulsion system is described using a finite number of operation points, which are characterized by different pairs of thruster input power. In order to guarantee the integral accuracy for the discrete power-limited problem, a power operation detection technique is embedded in the fourth-order Runge-Kutta algorithm with fixed step. Moreover, the logarithmic homotopy method and normalization technique are employed to overcome the difficulties caused by using indirect methods. Three numerical simulations with actual propulsion systems are given to substantiate the feasibility and efficiency of the proposed method.

  17. Detection Limits of DLS and UV-Vis Spectroscopy in Characterization of Polydisperse Nanoparticles Colloids

    Directory of Open Access Journals (Sweden)

    Emilia Tomaszewska

    2013-01-01

    Full Text Available Dynamic light scattering is a method that depends on the interaction of light with particles. This method can be used for measurements of narrow particle size distributions especially in the range of 2–500 nm. Sample polydispersity can distort the results, and we could not see the real populations of particles because big particles presented in the sample can screen smaller ones. Although the theory and mathematical basics of DLS technique are already well known, little has been done to determine its limits experimentally. The size and size distribution of artificially prepared polydisperse silver nanoparticles (NPs colloids were studied using dynamic light scattering (DLS and ultraviolet-visible (UV-Vis spectroscopy. Polydisperse colloids were prepared based on the mixture of chemically synthesized monodisperse colloids well characterized by atomic force microscopy (AFM, transmission electron microscopy (TEM, DLS, and UV-Vis spectroscopy. Analysis of the DLS results obtained for polydisperse colloids reveals that several percent of the volume content of bigger NPs could screen completely the presence of smaller ones. The presented results could be extremely important from nanoparticles metrology point of view and should help to understand experimental data especially for the one who works with DLS and/or UV-Vis only.

  18. STATISTICAL METHODS FOR ENVIRONMENTAL APPLICATIONS USING DATA SETS WITH BELOW DETECTION LIMIT OBSERVATIONS AS INCORPORTED IN PROUCL 4.0

    Science.gov (United States)

    Nondetect (ND) or below detection limit (BDL) results cannot be measured accurately, and, therefore, are reported as less than certain detection limit (DL) values. However, since the presence of some contaminants (e.g., dioxin) in environmental media may pose a threat to human he...

  19. Preparation of Environmental and Food Samples to Support the Heavy Metals Detection by Stripping Electrochemical

    International Nuclear Information System (INIS)

    Iswani S

    2002-01-01

    Preparation of environmental and food samples to support the heavy metals detection by stripping electrochemistry was done. The water samples taken directly from the ground water were acidified with 1 mL of HNO 3 acic suprapure was not digested, while the soils samples which have already dried in the oven at 105 o C, ware grinded and sieved through 150 μm, werte digested with HNO 3 acic suprapure in the digestion bomb at 150 o C for 3-4 hours. The mussels samples which have already freezed in the freezer were peeled, dried with N 2 liquid, grinded and dried again in the freeze drier at the pressure of ≅ 10 -2 mBar, and then were grinded again, weighted, digested with HNO 3 acic and HClO 4 suprapure in the digestion bomb at 150 o C for 3 hours. Food samples were homogenized by electric mixer, dried with freeze dried, homogenized again by using ZrO 2 ball mill, weighted, digested by HPA (high Pressure Asher). The heavy metals in the food samples solution of digestion product were detected by using Polarographic Analyzer EGandG of SWV and DPASV methods, while in the water, soils and the mussels solution were detected by using PDV 2000 and Polarograf E-505, DPASV method. The method validity were tested with SRM materials such as soil-5, soil-7, water W-4, and coppepoda. The heavy metals detection results in the water, soils, mussels, and food by electrochemical method were reported in this paper. (author)

  20. Utility of minimal preparation ct colonography in detecting colorectal cancer in elderly and frail patients.

    Science.gov (United States)

    Meiklejohn, D J; Ridley, L J; Ngu, M C; Cowlishaw, J L; Duller, A; Ridley, W

    2018-06-11

    Colorectal cancers result in substantial morbidity and mortality to Australian society each year. The usual investigation for bowel malignancyis optical colonoscopy (OC), withcomputed tomographic colonography (CTC) used as an alternative investigation. The catharsis and colon insufflation associated with these investigations pose a higher risk in the elderly and frail. Risks include perforation, serum electrolyte disturbance, and anaesthesia/sedation risks.Minimal preparation computed tomographic colonography (MPCTC) eliminates these risks. This paper audits a 6-year period ofMPCTC in an Australian tertiary referral hospital. 145 patients underwent MPCTC during the study period. There were 7 true positives, 2 false positives and 2 false negatives. Analysis of this population indicates a sensitivity of 0.78 (95% CI 0.51 - 1.05), specificity of 0.99 (95% CI 0.97 - 1.01), positive predictive value (PPV) of 0.78 (95% CI 0.51 - 1.05) and negative predictive value (NPV) of 0.99 (95% CI 0.97 - 1.01). These findings are concordant with other published studies. The auditconfirmsthatminimal preparation CT colonography is a reasonable alternative to OC and CTC in detecting colorectal cancer in symptomatic elderly and frail patients, without the procedural risks inherent inmore invasive investigations. For most patients MPCTC ruled out significant colorectal carcinoma with a high negative predictive value. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  1. In-house preparation of lectin panel and detection of Tn polyagglutination

    Directory of Open Access Journals (Sweden)

    Sudipta Sekhar Das

    2015-01-01

    Full Text Available Polyagglutination is a condition in which red cells are agglutinated by ABO-compatible adult human sera, but not by cord blood sera and may be acquired or inherited. Lectins are invaluable reagents in the investigation of red cells polyagglutination. We prepared in-house lectin panel and confirmed Tn polyagglutination in a pregnant lady. The lady was anemic and refused blood transfusion elsewhere due to serological discrepancy. We found ABO discrepancy and an incompatible minor cross-match in the initial investigation and suspected polyagglutination. Confirmation of polyagglutination was done using adult and cord sera. We then used the in-house lectin panels to detect the type of polyagglutination. The agglutination pattern with the various lectins was suggestive of Tn polyagglutination, which was further supported by the enzyme study. Most blood banks in India lack commercial lectin panels because of cost and procurement difficulty. Lectins play an important role in the diagnosis and differentiation of polyagglutination and immunohematological management of patient. The important and basic lectins can be prepared in-house using specific raw seeds following standardized protocol.

  2. In-house preparation of lectin panel and detection of Tn polyagglutination.

    Science.gov (United States)

    Das, Sudipta Sekhar

    2015-01-01

    Polyagglutination is a condition in which red cells are agglutinated by ABO-compatible adult human sera, but not by cord blood sera and may be acquired or inherited. Lectins are invaluable reagents in the investigation of red cells polyagglutination. We prepared in-house lectin panel and confirmed Tn polyagglutination in a pregnant lady. The lady was anemic and refused blood transfusion elsewhere due to serological discrepancy. We found ABO discrepancy and an incompatible minor cross-match in the initial investigation and suspected polyagglutination. Confirmation of polyagglutination was done using adult and cord sera. We then used the in-house lectin panels to detect the type of polyagglutination. The agglutination pattern with the various lectins was suggestive of Tn polyagglutination, which was further supported by the enzyme study. Most blood banks in India lack commercial lectin panels because of cost and procurement difficulty. Lectins play an important role in the diagnosis and differentiation of polyagglutination and immunohematological management of patient. The important and basic lectins can be prepared in-house using specific raw seeds following standardized protocol.

  3. RCRA materials analysis by laser-induced breakdown spectroscopy: Detection limits in soils

    International Nuclear Information System (INIS)

    Koskelo, A.; Cremers, D.A.

    1994-01-01

    The goal of the Technical Task Plan (TTP) that this report supports is research, development, testing and evaluation of a portable analyzer for RCRA and other metals. The instrumentation to be built will be used for field-screening of soils. Data quality is expected to be suitable for this purpose. The data presented in this report were acquired to demonstrate the detection limits for laser-induced breakdown spectroscopy (LIBS) of soils using instrument parameters suitable for fieldable instrumentation. The data are not expected to be the best achievable with the high pulse energies available in laboratory lasers. The report presents work to date on the detection limits for several elements in soils using LIBS. The elements targeted in the Technical Task Plan are antimony, arsenic, beryllium, cadmium, chromium, lead, selenium, and zirconium. Data for these elements are presented in this report. Also included are other data of interest to potential customers for the portable LIBS apparatus. These data are for barium, mercury, cesium and strontium. Data for uranium and thorium will be acquired during the tasks geared toward mixed waste characterization

  4. Analysis of detection limit to time-resolved coherent anti-Stokes Raman scattering nanoscopy

    International Nuclear Information System (INIS)

    Liu Wei; Liu Shuang-Long; Chen Dan-Ni; Niu Han-Ben

    2014-01-01

    In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit (DL) to time-resolved CARS (T-CARS) nanoscopy based on our proposed additional probe-beam-induced phonon depletion (APIPD) method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise (SNR) and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ∼ 10 9 W/cm 2 . When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume (40-nm suppressed focal scale in APIPD method), the DL correspondingly varies with exposure time, for example, DL values are 10 3 and 10 2 when exposure times are 20 ms and 200 ms respectively. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  5. DETERMINATION OF LIMIT DETECTION OF THE ELEMENTS N, P, K, Si, Al, Fe, Cu, Cd, WITH FAST NEUTRON ACTIVATION USING NEUTRON GENERATOR

    Directory of Open Access Journals (Sweden)

    Sunardi Sunardi

    2010-06-01

    Full Text Available Determination of limit detection of the elements N, P, K, Si, Al, Fe, Cu, Cd, with fast neutron activation using neutron generator has been done.  Samples prepared from SRM 2704, N, P, K elements from MERCK, Cu, Cd, Al from activation foil made in San Carlos, weighted and packed for certain weight then iradiated during 30 minutes with 14 MeV fast neutron using the neutron generator and then counted with gamma spectrometry (accuspec.  At this research condition of neutron generator was set at current 1 mA that produced neutron flux about 5,47.107 n/cm2.s and  experimental result shown that the limit detection for the elements N, P, K, Si, Al, Fe, Cu, Cd are  2,44 ppm, 1,88 ppm, 2,15 ppm, 1,44 ppm, 1,26 ppm, 1,35 ppm, 1,05 ppm, 2,99 ppm, respectively.  The data  indicate that the limit detection or sensitivity of appliance of neutron generator to analyze the element is very good, which is feasible to get accreditation AANC laboratory using neutron generator.   Keywords: limit detection, AANC, neutron generator

  6. Sample preparation for arsenic speciation analysis in baby food by generation of substituted arsines with atomic absorption spectrometry detection.

    Science.gov (United States)

    Huber, Charles S; Vale, Maria Goreti R; Dessuy, Morgana B; Svoboda, Milan; Musil, Stanislav; Dědina, Jiři

    2017-12-01

    A slurry sampling procedure for arsenic speciation analysis in baby food by arsane generation, cryogenic trapping and detection with atomic absorption spectrometry is presented. Several procedures were tested for slurry preparation, including different reagents (HNO 3 , HCl and tetramethylammonium hydroxide - TMAH) and their concentrations, water bath heating and ultrasound-assisted agitation. The best results for inorganic arsenic (iAs) and dimethylarsinate (DMA) were reached when using 3molL -1 HCl under heating and ultrasound-assisted agitation. The developed method was applied for the analysis of five porridge powder and six baby meal samples. The trueness of the method was checked with a certified reference material (CRM) of total arsenic (tAs), iAs and DMA in rice (ERM-BC211). Arsenic recoveries (mass balance) for all samples and CRM were performed by the determination of the tAs by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted digestion and its comparison against the sum of the results from the speciation analysis. The relative limits of detection were 0.44, 0.24 and 0.16µgkg -1 for iAs, methylarsonate and DMA, respectively. The concentrations of the most toxic arsenic species (iAs) in the analyzed baby food samples ranged between 4.2 and 99µgkg -1 which were below the limits of 300, 200 and 100µgkg -1 set by the Brazilian, Chinese and European legislation, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Calculation of risk-based detection limits for radionuclides in the liquid effluents from Korean nuclear power plants

    International Nuclear Information System (INIS)

    Cheong, Jae Hak

    2017-01-01

    In order to review if present detection limits of radionuclides in liquid effluent from nuclear power plants are effective enough to warrant compliance with regulatory discharge limits, a risk-based approach is developed to derive a new detection limit for each radionuclide based on radiological criteria. Equations and adjustment factors are also proposed to discriminate the validity of the detection limits for multiple radionuclides in the liquid effluent with or without consideration of the nuclide composition. From case studies to three nuclear power plants in Korea with actual operation data from 2006 to 2015, the present detection limits have turned out to be effective for Hanul Unit 1 but may not be sensitive enough for Kori Unit 1 (8 out of 14 radionuclides) and Wolsong Unit 1 (9 out of 42 radionuclides). However, it is shown that the present detection limits for the latter two nuclear power plants can be justified, if credit is given to the radionuclide composition. Otherwise, consideration should be given to adjustment of the present detection limits. The risk-based approach of this study can be used to determine the validity of established detection limits of a specific nuclear power plant. (author)

  8. Preparation of anti-ciguatoxin monoclonal antibodies using synthetic haptens: sandwich ELISA detection of ciguatoxins.

    Science.gov (United States)

    Tsumuraya, Takeshi; Fujii, Ikuo; Hirama, Masahiro

    2014-01-01

    Ciguatera fish poisoning (CFP) is a form of food poisoning caused by the consumption of fish that have accumulated a type of sodium channel activator toxin called ciguatoxins (CTXs), which are produced by dinoflagellates of the genus Gambierdiscus through the food chain. CFP affects more than 50000 people each year. The extremely low level of CTXs in tainted fish has hampered the development of antibodies for the detection of these toxins. Monoclonal antibodies (mAbs) specific against major congeners of CTX3C, 51-hydroxyCTX3C, CTX1B, and 54-deoxyCTX1B were prepared by immunization of mice with protein conjugates of rationally designed synthetic haptens in place of the natural toxins. We found that haptenic groups possessing a surface area larger than 400 angstroms2 were required to produce mAbs that can bind strongly to CTXs. Direct sandwich ELISA utilizing two different monoclonal antibodies that bind specifically to one of the two wings of a CTX were established to detect CTXs. No cross-reactivity was observed against the other marine toxins tested, including brevetoxin A, brevetoxin B, okadaic acid, and maitotoxin.

  9. The study on the lidar's detection limit for Iodine Gas

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-lyul; Baik, Seung-Hoon; Park, Seung-Kyu; Park, Nak-Gyu; Ahn, Yong-Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    A powerful and reliable tool for range-resolved remote sensing of gas concentrations that has proven its capabilities in a variety of studies is the differential absorption lidar (DIAL). Differential absorption lidar (DIAL) is frequently used for atmospheric gas monitoring to detect impurities such as nitrogen dioxide, sulfur dioxide, iodine, and ozone. DIAL can measure air pollutant concentrations with a high spatial resolution by adopting two laser systems with different degrees of absorption between the two different wavelengths. The absorption of the reference wavelength is very weak, while the absorption of the other wavelength is very strong. In this paper, we measured the limit of detection capability of our designed DIAL system. The DIAL measurements were performed using a target iodine cell in the laboratory. We confirmed that the concentration of iodine gas ratio increased after the laser passed through the iodine cell. The system of DIAL(Differential Absorption Lidar) was effective to detect the iodine gas. We obtained the signals from the iodine target cell and the lidar signal from the iodine target cell was proportional to frequency locking ratios.

  10. Confocal laser-induced fluorescence detector for narrow capillary system with yoctomole limit of detection.

    Science.gov (United States)

    Weaver, Mitchell T; Lynch, Kyle B; Zhu, Zaifang; Chen, Huang; Lu, Joann J; Pu, Qiaosheng; Liu, Shaorong

    2017-04-01

    Laser-induced fluorescence (LIF) detectors for low-micrometer and sub-micrometer capillary on-column detection are not commercially available. In this paper, we describe in details how to construct a confocal LIF detector to address this issue. We characterize the detector by determining its limit of detection (LOD), linear dynamic range (LDR) and background signal drift; a very low LOD (~70 fluorescein molecules or 12 yoctomole fluorescein), a wide LDR (greater than 3 orders of magnitude) and a small background signal drift (~1.2-fold of the root mean square noise) are obtained. For detecting analytes inside a low-micrometer and sub-micrometer capillary, proper alignment is essential. We present a simple protocol to align the capillary with the optical system and use the position-lock capability of a translation stage to fix the capillary in position during the experiment. To demonstrate the feasibility of using this detector for narrow capillary systems, we build a 2-μm-i.d. capillary flow injection analysis (FIA) system using the newly developed LIF prototype as a detector and obtain an FIA LOD of 14 zeptomole fluorescein. We also separate a DNA ladder sample by bare narrow capillary - hydrodynamic chromatography and use the LIF prototype to monitor the resolved DNA fragments. We obtain not only well-resolved peaks but also the quantitative information of all DNA fragments. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. A novel dNTP-limited PCR and HRM assay to detect Williams-Beuren syndrome.

    Science.gov (United States)

    Zhang, Lichen; Zhang, Xiaoqing; You, Guoling; Yu, Yongguo; Fu, Qihua

    2018-06-01

    Williams-Beuren syndrome (WBS) is caused by a microdeletion of chromosome arm 7q11.23. A rapid and inexpensive genotyping method to detect microdeletion on 7q11.23 needs to be developed for the diagnosis of WBS. This study describes the development of a new type of molecular diagnosis method to detect microdeletion on 7q11.23 based upon high-resolution melting (HRM). Four genes on 7q11.23 were selected as the target genes for the deletion genotyping. dNTP-limited duplex PCR was used to amplify the reference gene, CFTR, and one of the four genes respectively on 7q11.23. An HRM assay was performed on the PCR products, and the height ratio of the negative derivative peaks between the target gene and reference gene was employed to analyze the copy number variation of the target region. A new genotyping method for detecting 7q11.23 deletion was developed based upon dNTP-limited PCR and HRM, which cost only 96 min. Samples from 15 WBS patients and 12 healthy individuals were genotyped by this method in a blinded fashion, and the sensitivity and specificity was 100% (95% CI, 0.80-1, and 95% CI, 0.75-1, respectively) which was proved by CytoScan HD array. The HRM assay we developed is an rapid, inexpensive, and highly accurate method for genotyping 7q11.23 deletion. It is potentially useful in the clinical diagnosis of WBS. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. WE-H-207A-09: Theoretical Limits to Molecular Biomarker Detection Using Magnetic Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, J [Dartmouth-Hitchcock Medical Center, Lebanon, NH (United States); Geisel School of Medicine, Dartmouth College, Hanover, NH (United States)

    2016-06-15

    Purpose: Estimate the limits of molecular biomarker detection using magnetic nanoparticle methods like in vivo ELISA. Methods: Magnetic nanoparticles in an alternating magnetic field produce a magnetization that can be detected at exceedingly low levels because the signal at the harmonic frequencies is uniquely produced by the nanoparticles. Because the magnetization can also be used to characterize the nanoparticle rotational freedom, the bound state can be found. If the nanoparticles are coated with molecules that bind the desired biomarker, the rotational freedom reflects the biomarker concentration. The irreducible noise limit is the thermal noise or Johnson noise of the tissue and the contrast that can be measured must be larger than that limit. The contrast produced is a function of the applied field and depends strongly on nanoparticle volume. We have estimated the contrast using a Langevin function of a single composite variable to approximate the full stochastic Langevin equation for nanoparticle dynamics. Results: The thermal noise for a bandwidth reasonable for spectroscopy suggests mid zeptomolar (10–21) to low attomolar (10–18) concentrations can be measured in a volume that is 10cm in scale. The suggested sensitivity is far below the physiologically concentrations of almost all critical biomarkers including cytokines (picomolar), hormones (nanomolar) and heat shock proteins. Conclusion: The sensitivity of in vivo ELISA concentration measurements should be sufficient to measure physiological concentrations of critical biomarkers like cytokines in vivo. Further the sensitivity should be sufficient to measure concentrations of other biomarkers that are six to eight orders of magnitude lower in concentration than immune signaling molecules like cytokines. NIH - 1U54CA151662-01 Department of Radiology.

  13. Limit of detection of a fiber optics gyroscope using a super luminescent radiation source

    International Nuclear Information System (INIS)

    Sandoval R, G.E.; Nikolaev, V.A.

    2003-01-01

    The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which is determined with the shot noise. (Author)

  14. Limit of detection of a fiber optics gyroscope using a super luminescent radiation source

    CERN Document Server

    Sandoval, G E

    2003-01-01

    The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which i...

  15. 40 CFR Appendix B to Part 136 - Definition and Procedure for the Determination of the Method Detection Limit-Revision 1.11

    Science.gov (United States)

    2010-07-01

    ... calculated method detection limit. To insure that the estimate of the method detection limit is a good...) where: MDL = the method detection limit t(n-1,1- α=.99) = the students' t value appropriate for a 99... Determination of the Method Detection Limit-Revision 1.11 B Appendix B to Part 136 Protection of Environment...

  16. Ebolavirus diagnosis made simple, comparable and faster than molecular detection methods: preparing for the future.

    Science.gov (United States)

    James, Ameh S; Todd, Shawn; Pollak, Nina M; Marsh, Glenn A; Macdonald, Joanne

    2018-04-23

    The 2014/2015 Ebolavirus outbreak resulted in more than 28,000 cases and 11,323 reported deaths, as of March 2016. Domestic transmission of the Guinea strain associated with the outbreak occurred mainly in six African countries, and international transmission was reported in four countries. Outbreak management was limited by the inability to rapidly diagnose infected cases. A further fifteen countries in Africa are predicted to be at risk of Ebolavirus outbreaks in the future as a consequence of climate change and urbanization. Early detection of cases and reduction of transmission rates is critical to prevent and manage future severe outbreaks. We designed a rapid assay for detection of Ebolavirus using recombinase polymerase amplification, a rapid isothermal amplification technology that can be combined with portable lateral flow detection technology. The developed rapid assay operates in 30 min and was comparable with real-time TaqMan™ PCR. Designed, screened, selected and optimized oligonucleotides using the NP coding region from Ebola Zaire virus (Guinea strain). We determined the analytical sensitivity of our Ebola rapid molecular test by testing selected primers and probe with tenfold serial dilutions (1.34 × 10 10-  1.34 × 10 1 copies/μL) of cloned NP gene from Mayinga strain of Zaire ebolavirus in pCAGGS vector, and serially diluted cultured Ebolavirus as established by real-time TaqMan™ PCR that was performed using ABI7500 in Fast Mode. We tested extracted and reverse transcribed RNA from cultured Zaire ebolavirus strains - Mayinga, Gueckedou C05, Gueckedou C07, Makona, Kissidougou and Kiwit. We determined the analytical specificity of our assay with related viruses: Marburg, Ebola Reston and Ebola Sudan. We further tested for Dengue virus 1-4, Plasmodium falciparum and West Nile Virus (Kunjin strain). The assay had a detection limit of 134 copies per μL of plasmid containing the NP gene of Ebolavirus Mayinga, and cultured Ebolavirus

  17. Evaluation of MidIR fibre optic reflectance: Detection limit, reproducibility and binary mixture discrimination

    Science.gov (United States)

    Sessa, Clarimma; Bagán, Héctor; García, José Francisco

    2013-11-01

    MidIR fibre optic reflectance (MidIR-FORS) is a promising analytical technique in the field of science conservation, especially because it is non-destructive. Another advantage of MidIR-FORS is that the obtained information is representative, as a large amount of spectral data can be collected. Although the technique has a high potential and is almost routinely applied, its quality parameters have not been thoroughly studied in the specific application of analysis of artistic materials. The objective of this study is to evaluate the instrumental capabilities of MidIR-FORS for the analysis of artwork materials in terms of detection limit, reproducibility, and mixture characterisation. The study has been focused on oil easel painting and several paints of known composition have been analysed. Paint layers include blue pigments not only because of their important role along art history, but also because their physical and spectroscopic characteristics allow a better evaluation of the MidIR-FORS capabilities. The results of the analysis indicate that MidIR-FORS supplies a signal affected by different factors, such as the optical, morphological and physical properties of the surface, in addition to the composition of materials analysed. Consequently, the detection limits established are relatively high for artistic objects (Prussian blue - PB 2.1-6.5%; Phthalocyanine blue - Pht 6.3-10.2%; synthetic Ultramarine blue - UM 12.1%) and may therefore lead to an incomplete description of the artwork. Reproducibility of the technique over time and across surface has been determined. The results show that the major sources of dispersion are the heterogeneity of the pigments distribution, physical features, and band shape distortions. The total dispersion is around 4% for the most intense bands (oil) and increases up to 26% when weak or overlapped bands are considered (PB, Pht, UM). The application of different pre-treatments (cutoff of fibres absorption, Savizky-Golay smoothing

  18. Composite Estimation for Single-Index Models with Responses Subject to Detection Limits

    KAUST Repository

    Tang, Yanlin; Wang, Huixia Judy; Liang, Hua

    2017-01-01

    We propose a semiparametric estimator for single-index models with censored responses due to detection limits. In the presence of left censoring, the mean function cannot be identified without any parametric distributional assumptions, but the quantile function is still identifiable at upper quantile levels. To avoid parametric distributional assumption, we propose to fit censored quantile regression and combine information across quantile levels to estimate the unknown smooth link function and the index parameter. Under some regularity conditions, we show that the estimated link function achieves the non-parametric optimal convergence rate, and the estimated index parameter is asymptotically normal. The simulation study shows that the proposed estimator is competitive with the omniscient least squares estimator based on the latent uncensored responses for data with normal errors but much more efficient for heavy-tailed data under light and moderate censoring. The practical value of the proposed method is demonstrated through the analysis of a human immunodeficiency virus antibody data set.

  19. Towards improving the detection limit of electron paramagnetic resonance (EPR) dosimetry of drywall (wallboard)

    Energy Technology Data Exchange (ETDEWEB)

    Mistry, R.; Thompson, J.W. [Dept. of Medical Physics and Applied Radiation Sciences, McMaster Univ., Hamilton, Ontario (Canada); Rink, W.J. [School of Geography and Earth Sciences, McMaster Univ., Hamilton, Ontario (Canada); Boreham, D. [Dept. of Medical Physics and Applied Radiation Sciences, McMaster Univ., Hamilton, Ontario (Canada)

    2009-07-01

    The intensity of the electron paramagnetic resonance (EPR) line corresponding to the carbonate free radical (CO{sub 3}{sup -}) in gypsum (CaSO{sub 4}{center_dot}2H{sub 2}O) drywall was previously shown to be proportional to absorbed dose. Heating irradiated drywall reduces the radiosensitive signal of the CO{sub 3}{sup -} radical. The response of the CO{sub 3}{sup -} EPR line to heat treatments is being studied in order to determine a background for an arbitrary drywall sample. Ultimately this is expected to improve the precision of dose measurements with drywall and to reduce the detection limit. Controlled heating of irradiated drywall was performed at temperatures between 50{sup o}C and 100{sup o}C. Although higher temperatures reduce the radiosensitive signal rapidly, the non-radiosensitive EPR signals are affected dramatically as well, presumably due to a phrase change from gypsum to plaster of Paris to anhydrite. (author)

  20. Determination of limits for smallest detectable and largest subcritical leakage cracks in piping systems

    International Nuclear Information System (INIS)

    Bieselt, R.; Wolf, M.

    1995-01-01

    Nuclear power plant piping systems - those still in their original as-built condition as well as upgraded designs - are subject to safety analysis. In order to limit the consequences of postulated piping failures, the basic safety concept incorporating rupture preclusion criteria is applied to specific high-energy piping systems. Leak-before-break analyses are also conducted within the framework of this concept. These analyses serve to determine the potential consequences of jet and reaction forces due to maximum subcritical leakage cracks while also establishing the minimum crack sizes that would be reliably detectable by the leakage rates resulting from these cracks. The boundary conditions for these analyses are not clearly defined. Using various examples as a basis, this paper presents and discusses how the leak-before-break concept can be applied. (orig.)

  1. Composite Estimation for Single-Index Models with Responses Subject to Detection Limits

    KAUST Repository

    Tang, Yanlin

    2017-11-03

    We propose a semiparametric estimator for single-index models with censored responses due to detection limits. In the presence of left censoring, the mean function cannot be identified without any parametric distributional assumptions, but the quantile function is still identifiable at upper quantile levels. To avoid parametric distributional assumption, we propose to fit censored quantile regression and combine information across quantile levels to estimate the unknown smooth link function and the index parameter. Under some regularity conditions, we show that the estimated link function achieves the non-parametric optimal convergence rate, and the estimated index parameter is asymptotically normal. The simulation study shows that the proposed estimator is competitive with the omniscient least squares estimator based on the latent uncensored responses for data with normal errors but much more efficient for heavy-tailed data under light and moderate censoring. The practical value of the proposed method is demonstrated through the analysis of a human immunodeficiency virus antibody data set.

  2. Amorphous semiconductors for particle detection: Physical and technical limits and possibilities

    International Nuclear Information System (INIS)

    Equer, B.; Karar, A.

    1989-01-01

    Amorphous silicon is used, at an industrial level, in at least three different fields of application: photovoltaic cells, flat TV screens and line scanners for image processing. In the last two cases, thin film transistors (TFT) are produced with the same technology. Particle detection with amorphous silicon has been demonstrated, but present performances are limited to ionizing particles. In this paper, we discuss the physical basis of amorphous semiconductors and the possible future development that can be expected on the basis of the existing technology. It is concluded that substitution of amorphous for crystalline silicon brings no clear advantage, if possible at all. Positive assets are to be found in using specific properties of thin layers: large area structures like arrays of photodiodes with associated readout are in the state of the art; vertical structures alternating layers of differently doped materials and/or of different semiconductors can be produced by the same technique. The development of large area pixel detectors is technically feasible but requires a very large effort. A joint development effort with industries involved in X-ray detection and 2D photodetectors might be the most appropriate solution. (orig.)

  3. Potential and limits of Raman spectroscopy for carotenoid detection in microorganisms: implications for astrobiology

    Science.gov (United States)

    Jehlička, Jan; Edwards, Howell G. M.; Osterrothová, Kateřina; Novotná, Julie; Nedbalová, Linda; Kopecký, Jiří; Němec, Ivan; Oren, Aharon

    2014-01-01

    In this paper, it is demonstrated how Raman spectroscopy can be used to detect different carotenoids as possible biomarkers in various groups of microorganisms. The question which arose from previous studies concerns the level of unambiguity of discriminating carotenoids using common Raman microspectrometers. A series of laboratory-grown microorganisms of different taxonomic affiliation was investigated, such as halophilic heterotrophic bacteria, cyanobacteria, the anoxygenic phototrophs, the non-halophilic heterotrophs as well as eukaryotes (Ochrophyta, Rhodophyta and Chlorophyta). The data presented show that Raman spectroscopy is a suitable tool to assess the presence of carotenoids of these organisms in cultures. Comparison is made with the high-performance liquid chromatography approach of analysing pigments in extracts. Direct measurements on cultures provide fast and reliable identification of the pigments. Some of the carotenoids studied are proposed as tracers for halophiles, in contrast with others which can be considered as biomarkers of other genera. The limits of application of Raman spectroscopy are discussed for a few cases where the current Raman spectroscopic approach does not allow discriminating structurally very similar carotenoids. The database reported can be used for applications in geobiology and exobiology for the detection of pigment signals in natural settings. PMID:25368348

  4. Breath Analysis Using Laser Spectroscopic Techniques: Breath Biomarkers, Spectral Fingerprints, and Detection Limits

    Directory of Open Access Journals (Sweden)

    Peeyush Sahay

    2009-10-01

    Full Text Available Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS, cavity ringdown spectroscopy (CRDS, integrated cavity output spectroscopy (ICOS, cavity enhanced absorption spectroscopy (CEAS, cavity leak-out spectroscopy (CALOS, photoacoustic spectroscopy (PAS, quartz-enhanced photoacoustic spectroscopy (QEPAS, and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS. Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis.

  5. Left ventricular time volume curve analysis in the detection of limited ischaemic heart disease

    International Nuclear Information System (INIS)

    Liechtenstein, M.; Blanchett, W.; Andrews, J.; Hunt, D.

    1982-01-01

    The aim of the study was to determine whether limited coronary artery disease (CAD) could be accurately detected using the Cardiac Gated Blood Pool (CGBP) scan with exercise. Regional left ventricular time volume curves (RLTVD) were generated from 52 studies (46 patients: 22 normals, 24 abnormals). The parameters assessed both globally and regionally and at rest (R) and exercise (Ex) were: (1) the ejection fraction (EF) (2) the change in ejection fraction from R to Ex (δEF) (3) an early contraction index (ECI) (4) a maximal emptying index (DR) and (5) a maximal refilling index (AR). After careful analysis of these parameters it was decided that our diagnostic criteria would rely on the following: (1) the EF at R and Ex (2) the δ EF (3) the ECI at Ex (4) the AR at Ex This study showed that both the sensitivity and the specificity of the CGBP scan can be improved considerably with the inclusion of RLTVC from the levels obtained when the EF parameters alone are considered. It is possible with this technique to accurately diagnose limited CAD. (Author)

  6. DETERMINATION OF LIMIT DETECTION OF THE ELEMENTS N, P, K, Si, Al, Fe, Cu, Cd, WITH FAST NEUTRON ACTIVATION USING NEUTRON GENERATOR

    OpenAIRE

    Sunardi, Sunardi; Muryono, Muryono

    2010-01-01

    Determination of limit detection of the elements N, P, K, Si, Al, Fe, Cu, Cd, with fast neutron activation using neutron generator has been done.  Samples prepared from SRM 2704, N, P, K elements from MERCK, Cu, Cd, Al from activation foil made in San Carlos, weighted and packed for certain weight then iradiated during 30 minutes with 14 MeV fast neutron using the neutron generator and then counted with gamma spectrometry (accuspec).  At this research condition of neutron generator was set at...

  7. Automated radioanalytical system incorporating microwave-assisted sample preparation, chemical separation, and online radiometric detection for the monitoring of total 99Tc in nuclear waste processing streams.

    Science.gov (United States)

    Egorov, Oleg B; O'Hara, Matthew J; Grate, Jay W

    2012-04-03

    An automated fluidic instrument is described that rapidly determines the total (99)Tc content of aged nuclear waste samples, where the matrix is chemically and radiologically complex and the existing speciation of the (99)Tc is variable. The monitor links microwave-assisted sample preparation with an automated anion exchange column separation and detection using a flow-through solid scintillator detector. The sample preparation steps acidify the sample, decompose organics, and convert all Tc species to the pertechnetate anion. The column-based anion exchange procedure separates the pertechnetate from the complex sample matrix, so that radiometric detection can provide accurate measurement of (99)Tc. We developed a preprogrammed spike addition procedure to automatically determine matrix-matched calibration. The overall measurement efficiency that is determined simultaneously provides a self-diagnostic parameter for the radiochemical separation and overall instrument function. Continuous, automated operation was demonstrated over the course of 54 h, which resulted in the analysis of 215 samples plus 54 hly spike-addition samples, with consistent overall measurement efficiency for the operation of the monitor. A sample can be processed and measured automatically in just 12.5 min with a detection limit of 23.5 Bq/mL of (99)Tc in low activity waste (0.495 mL sample volume), with better than 10% RSD precision at concentrations above the quantification limit. This rapid automated analysis method was developed to support nuclear waste processing operations planned for the Hanford nuclear site.

  8. Preparation and evaluation of Exendin radio conjugates for detecting insulinomas and gastrinomas by molecular nuclear medicine techniques

    International Nuclear Information System (INIS)

    Medina G, V.

    2015-01-01

    The gastro-entero-pancreatic neuroendocrine tumors (GEP-NET) are named based on the secreted hormones. Among them, the insulinomas and gastrinomas represent a diagnostic challenge because of their slow metabolic rate, small size and anatomical location that have limited their detection in some imaging procedures. About 90% of insulinomas are benign and 10% are malignant. Benign insulinomas express the glucagon-like peptide-1 receptor (GLP-1R) and low levels of somatostatin receptors (SSTR), while malignant insulinomas over express SSTR or GLP-1R in low levels. A kit for the preparation of Lys 27 ( 99m Tc-EDDA/HYNIC)-Exendin(9-39)/ 99m Tc-EDDA/HYNIC-Tyr 3 -Octreotide was developed to detect 100% of gastrinomas and insulinomas. In order to reach this aim, the peptides were radiolabeled and characterized. Stability studies will be completed and the in vitro and in vivo behavior was evaluated. The Lys 27 ( 99m Tc-EDDA/HYNIC)-Exendin(9-39)/ 99m Tc-EDDA/HYNIC-Tyr 3 -Octreotide can be labeled with 99m Tc, obtaining high radiochemical purities (>94%), high stability in human serum and affinity to GLP-1 and SST-2 receptor. This new formulation showed properties suitable for use as a target-specific agent for molecular imaging of GLP-1R/SSTR positive tumors. In vivo micro-SPECT/CT images of Lys 27 ( 99m Tc-EDDA/HYNIC)-Exendin(9-39), 99m Tc-EDDA/HYNIC-Tyr 3 -Octreotide and of the pharmaceutical formulation Lys 27 ( 99m Tc-EDDA/HYNIC)-Exendin(9-39)/ 99m Tc-EDDA/HYNIC-Tyr 3 -Octreotide showed the main elimination pathways, and tumors higher uptake compared to the background tissues. The biodistribution and imaging studies demonstrated properties suitable for its use as a target-specific agent for the simultaneous molecular imaging of GLP-1R and SSTR. (Author)

  9. Magnetic resonance colonography with a limited bowel preparation and automated carbon dioxide insufflation in comparison to conventional colonoscopy: Patient burden and preferences

    Energy Technology Data Exchange (ETDEWEB)

    Paardt, M.P. van der, E-mail: m.p.vanderpaardt@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Boellaard, T.N., E-mail: t.n.boellaard@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Zijta, F.M., E-mail: fmzijta@yahoo.com [Department of Radiology, Medisch Centrum Haaglanden, Den Haag (Netherlands); Baak, L.C., E-mail: l.c.baak@olvg.nl [Department of Gastroenterology and Hepatology, Onze Lieve Vrouwe Gasthuis, Amsterdam (Netherlands); Depla, A.C.T.M., E-mail: actm.depla@slz.nl [Department of Gastroenterology and Hepatology, Slotervaartziekenhuis, Amsterdam (Netherlands); Dekker, E., E-mail: e.dekker@amc.uva.nl [Department of Gastroenterology and Hepatology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Nederveen, A.J., E-mail: a.j.nederveen@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Bipat, S., E-mail: s.bipat@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands); Stoker, J., E-mail: j.stoker@amc.uva.nl [Department of Radiology, Academic Medical Center Amsterdam, Amsterdam (Netherlands)

    2015-01-15

    Highlights: • MR colonography with a limited bowel preparation and automated carbon dioxide insufflation demonstrated less burden compared to colonoscopy. • When discarding the bowel preparation, the examinations were rated equally burdensome. • The majority of patients preferred MR colonography over colonoscopy for their future examination of the bowel. - Abstract: Objectives: To evaluate patient burden and preferences for MR colonography with a limited bowel preparation and automated carbon dioxide insufflation in comparison to conventional colonoscopy. Methods: Symptomatic patients were consecutively recruited to undergo MR colonography with automated carbon dioxide insufflation and a limited bowel preparation followed within four weeks by colonoscopy with a standard bowel cleansing preparation. Four questionnaires regarding burden (on a five-point scale) and preferences (on a seven-point scale) were addressed after MR colonography and colonoscopy and five weeks after colonoscopy. Results: Ninety-nine patients (47 men, 52 women; mean age 62.3, SD 8.7) were included. None of the patients experienced severe or extreme burden from the MR colonography bowel preparation compared to 31.5% of the patients for the colonoscopy bowel preparation. Colonoscopy was rated more burdensome (25.6% severe or extreme burden) compared to MR colonography (5.2% severe or extreme burden) (P < 0.0001). When discarding the bowel preparations, the examinations were rated equally burdensome (P = 0.35). The majority of patients (61.4%) preferred MR colonography compared to colonoscopy (29.5%) immediately after the examinations and five weeks later (57.0% versus 39.5%). Conclusion: MR colonography with a limited bowel preparation and automated carbon dioxide insufflation demonstrated less burden compared to colonoscopy. The majority of patients preferred MR colonography over colonoscopy.

  10. Research on the preparation, uniformity and stability of mixed standard substance for rapid detection of goat milk composition.

    Science.gov (United States)

    Zhu, Yuying; Wang, Jianmin; Wang, Cunfang

    2018-05-01

    Taking fresh goat milk as raw material after filtering, centrifuging, hollow fiber ultrafiltration, allocating formula, value detection and preparation processing, a set of 10 goat milk mixed standard substances was prepared on the basis of one-factor-at-a-time using a uniform design method, and its accuracy, uniformity and stability were evaluated by paired t-test and F-test of one-way analysis of variance. The results showed that three milk composition contents of these standard products were independent of each other, and the preparation using the quasi-level design method, and without emulsifier was the best program. Compared with detection value by cow milk standards for calibration fast analyzer, the calibration by goat milk mixed standard was more applicable to rapid detection of goat milk composition, detection value was more accurate and the deviation showed less error. Single factor analysis of variance showed that the uniformity and stability of the mixed standard substance were better; it could be stored for 15 days at 4°C. The uniformity and stability of the in-units and inter-units could meet the requirements of the preparation of national standard products. © 2018 Japanese Society of Animal Science.

  11. Investigation of detection limits for diffuse optical tomography systems: II. Analysis of slab and cup geometry for breast imaging.

    Science.gov (United States)

    Ziegler, Ronny; Brendel, Bernhard; Rinneberg, Herbert; Nielsen, Tim

    2009-01-21

    Using a statistical (chi-square) test on simulated data and a realistic noise model derived from the system's hardware we study the performance of diffuse optical tomography systems for fluorescence imaging. We compare the predicted smallest size of detectable lesions at various positions in slab and cup geometry and model how detection sensitivity depends on breast compression and lesion fluorescence contrast. Our investigation shows that lesion detection is limited by relative noise in slab geometry and by absolute noise in cup geometry.

  12. Detection of maximum loadability limits and weak buses using Chaotic PSO considering security constraints

    International Nuclear Information System (INIS)

    Acharjee, P.; Mallick, S.; Thakur, S.S.; Ghoshal, S.P.

    2011-01-01

    Highlights: → The unique cost function is derived considering practical Security Constraints. → New innovative formulae of PSO parameters are developed for better performance. → The inclusion and implementation of chaos in PSO technique is original and unique. → Weak buses are identified where FACTS devices can be implemented. → The CPSO technique gives the best performance for all the IEEE standard test systems. - Abstract: In the current research chaotic search is used with the optimization technique for solving non-linear complicated power system problems because Chaos can overcome the local optima problem of optimization technique. Power system problem, more specifically voltage stability, is one of the practical examples of non-linear, complex, convex problems. Smart grid, restructured energy system and socio-economic development fetch various uncertain events in power systems and the level of uncertainty increases to a great extent day by day. In this context, analysis of voltage stability is essential. The efficient method to assess the voltage stability is maximum loadability limit (MLL). MLL problem is formulated as a maximization problem considering practical security constraints (SCs). Detection of weak buses is also important for the analysis of power system stability. Both MLL and weak buses are identified by PSO methods and FACTS devices can be applied to the detected weak buses for the improvement of stability. Three particle swarm optimization (PSO) techniques namely General PSO (GPSO), Adaptive PSO (APSO) and Chaotic PSO (CPSO) are presented for the comparative study with obtaining MLL and weak buses under different SCs. In APSO method, PSO-parameters are made adaptive with the problem and chaos is incorporated in CPSO method to obtain reliable convergence and better performances. All three methods are applied on standard IEEE 14 bus, 30 bus, 57 bus and 118 bus test systems to show their comparative computing effectiveness and

  13. In situ Silver Spot Preparation and on-Plate Surface-Enhanced Raman Scattering Detection in Thin Layer Chromatography Separation

    Science.gov (United States)

    Herman, K.; Mircescu, N. E.; Szabo, L.; Leopold, L. F.; Chiş, V.; Leopold, N.

    2013-05-01

    An improved approach for surface-enhanced Raman scattering (SERS) detection of mixture constituents after thin layer chromatography (TLC) separation is presented. A SERS active silver substrate was prepared under open air conditions, directly on the thin silica film by photo-reduction of silver nitrate, allowing the detection of binary mixtures of cresyl violet, bixine, crystal violet, and Cu(II) complex of 4-(2-pyridylazo)resorcinol. The recorded SERS spectrum provides a unique spectral fingerprint for each molecule; therefore the use of analyte standards is avoided, thus rendering the presented procedure advantageous compared to the conventional detection methodology in TLC.

  14. Proposal for a methodology for the determination of the Detection Limit: Case of bulks detector for the Chlorothalonil

    International Nuclear Information System (INIS)

    Gonzalez G, J.; Parra M, C.M.; Romero R, R.M.

    1998-01-01

    As it usually found in the literature, the Lower Detection Limit for an analytical method is obtained by means of a simple statistical exercise whose value is seldom attained in practice. For this reason a method was designed for achieving a Practical Lower Detection Limit for the lowest concentration of the compound that could be detected, S= 2 R, with a probability of at least, 0.90. A methodological design was formulated to get a Practical Lower Detection Limit that is not timed consuming for the analyst. It is presented using an example and, additionally its benefits are discussed versus the unattainable values that are obtained by the traditional use of the standard deviation of a series of measurements of the compound at concentrations near zero, which is then multiplied by the t student for a one tailed test for n-1 degrees of freedom

  15. The Use and Abuse of Limits of Detection in Environmental Analytical Chemistry

    Directory of Open Access Journals (Sweden)

    Richard J. C. Brown

    2008-01-01

    Full Text Available The limit of detection (LoD serves as an important method performance measure that is useful for the comparison of measurement techniques and the assessment of likely signal to noise performance, especially in environmental analytical chemistry. However, the LoD is only truly related to the precision characteristics of the analytical instrument employed for the analysis and the content of analyte in the blank sample. This article discusses how other criteria, such as sampling volume, can serve to distort the quoted LoD artificially and make comparison between various analytical methods inequitable. In order to compare LoDs between methods properly, it is necessary to state clearly all of the input parameters relating to the measurements that have been used in the calculation of the LoD. Additionally, the article discusses that the use of LoDs in contexts other than the comparison of the attributes of analytical methods, in particular when reporting analytical results, may be confusing, less informative than quoting the actual result with an accompanying statement of uncertainty, and may act to bias descriptive statistics.

  16. Improved detection limits for phthalates by selective solid-phase micro-extraction

    KAUST Repository

    Zia, Asif I.

    2016-03-30

    Presented research reports on an improved method and enhanced limits of detection for phthalates; a hazardous additive used in the production of plastics by solid-phase micro-extraction (SPME) polymer in comparison to molecularly imprinted solid-phase extraction (MISPE) polymer. The polymers were functionalized on an interdigital capacitive sensor for selective binding of phthalate molecules from a complex mixture of chemicals. Both polymers owned predetermined selectivity by formation of valuable molecular recognition sites for Bis (2-ethylhexyl) phthalate (DEHP). Polymers were immobilized on planar electrochemical sensor fabricated on a single crystal silicon substrate with 500 nm sputtered gold electrodes fabricated using MEMS fabrication techniques. Impedance spectra were obtained using electrochemical impedance spectroscopy (EIS) to determine sample conductance for evaluation of phthalate concentration in the spiked sample solutions with various phthalate concentrations. Experimental results revealed that the ability of SPME polymer to adsorb target molecules on the sensing surface is better than that of MISPE polymer for phthalates in the sensing system. Testing the extracted samples using high performance liquid chromatography with photodiode array detectors validated the results.

  17. Probe-Specific Procedure to Estimate Sensitivity and Detection Limits for 19F Magnetic Resonance Imaging.

    Directory of Open Access Journals (Sweden)

    Alexander J Taylor

    Full Text Available Due to low fluorine background signal in vivo, 19F is a good marker to study the fate of exogenous molecules by magnetic resonance imaging (MRI using equilibrium nuclear spin polarization schemes. Since 19F MRI applications require high sensitivity, it can be important to assess experimental feasibility during the design stage already by estimating the minimum detectable fluorine concentration. Here we propose a simple method for the calibration of MRI hardware, providing sensitivity estimates for a given scanner and coil configuration. An experimental "calibration factor" to account for variations in coil configuration and hardware set-up is specified. Once it has been determined in a calibration experiment, the sensitivity of an experiment or, alternatively, the minimum number of required spins or the minimum marker concentration can be estimated without the need for a pilot experiment. The definition of this calibration factor is derived based on standard equations for the sensitivity in magnetic resonance, yet the method is not restricted by the limited validity of these equations, since additional instrument-dependent factors are implicitly included during calibration. The method is demonstrated using MR spectroscopy and imaging experiments with different 19F samples, both paramagnetically and susceptibility broadened, to approximate a range of realistic environments.

  18. Probe-Specific Procedure to Estimate Sensitivity and Detection Limits for 19F Magnetic Resonance Imaging.

    Science.gov (United States)

    Taylor, Alexander J; Granwehr, Josef; Lesbats, Clémentine; Krupa, James L; Six, Joseph S; Pavlovskaya, Galina E; Thomas, Neil R; Auer, Dorothee P; Meersmann, Thomas; Faas, Henryk M

    2016-01-01

    Due to low fluorine background signal in vivo, 19F is a good marker to study the fate of exogenous molecules by magnetic resonance imaging (MRI) using equilibrium nuclear spin polarization schemes. Since 19F MRI applications require high sensitivity, it can be important to assess experimental feasibility during the design stage already by estimating the minimum detectable fluorine concentration. Here we propose a simple method for the calibration of MRI hardware, providing sensitivity estimates for a given scanner and coil configuration. An experimental "calibration factor" to account for variations in coil configuration and hardware set-up is specified. Once it has been determined in a calibration experiment, the sensitivity of an experiment or, alternatively, the minimum number of required spins or the minimum marker concentration can be estimated without the need for a pilot experiment. The definition of this calibration factor is derived based on standard equations for the sensitivity in magnetic resonance, yet the method is not restricted by the limited validity of these equations, since additional instrument-dependent factors are implicitly included during calibration. The method is demonstrated using MR spectroscopy and imaging experiments with different 19F samples, both paramagnetically and susceptibility broadened, to approximate a range of realistic environments.

  19. On the limitations introduced by energy spread in elastic recoil detection analysis

    International Nuclear Information System (INIS)

    Szilagyi, E.

    2001-01-01

    Improvements in experimental techniques have led to monolayer depth resolution in heavy ion elastic recoil detection analysis (HI-ERDA). Evaluation of the spectra, however, is not trivial. The spectra, using even the best experimental set-up, are subject to finite energy resolution of both extrinsic and intrinsic origin. A proper account for energy spread is necessary to extract the correct depth profile from the measured spectra. With calculation of the correct energy (or depth) resolution of a given method, one can decide in advance whether or not the method will resolve details of interest in the depth profile. To achieve the best depth resolution, it is also possible to find optimum parameters for the experiments. The limitations introduced by the energy spread effects are discussed. An example for simulation is shown for high energy resolution HI-ERDA measurements. Satisfactory agreement between the simulated and the measured HI-ERDA spectra taken by 60 MeV 127 I 23+ ions on highly oriented pyrolythic graphite (HOPG) sample is found, in spite of the non-equilibrium charge state of the recoils and the difference in the stopping powers caused by the given charge state of the incident ion and the recoil, which are not taken into account. To achieve more precise data evaluation these effects should be included in simulation codes, or all the subspectra corresponding to different recoils charge states should be measured and summed

  20. On the limitations introduced by energy spread in elastic recoil detection analysis

    Energy Technology Data Exchange (ETDEWEB)

    Szilagyi, E. E-mail: szilagyi@rmki.kfki.hu

    2001-07-01

    Improvements in experimental techniques have led to monolayer depth resolution in heavy ion elastic recoil detection analysis (HI-ERDA). Evaluation of the spectra, however, is not trivial. The spectra, using even the best experimental set-up, are subject to finite energy resolution of both extrinsic and intrinsic origin. A proper account for energy spread is necessary to extract the correct depth profile from the measured spectra. With calculation of the correct energy (or depth) resolution of a given method, one can decide in advance whether or not the method will resolve details of interest in the depth profile. To achieve the best depth resolution, it is also possible to find optimum parameters for the experiments. The limitations introduced by the energy spread effects are discussed. An example for simulation is shown for high energy resolution HI-ERDA measurements. Satisfactory agreement between the simulated and the measured HI-ERDA spectra taken by 60 MeV {sup 127}I{sup 23+} ions on highly oriented pyrolythic graphite (HOPG) sample is found, in spite of the non-equilibrium charge state of the recoils and the difference in the stopping powers caused by the given charge state of the incident ion and the recoil, which are not taken into account. To achieve more precise data evaluation these effects should be included in simulation codes, or all the subspectra corresponding to different recoils charge states should be measured and summed.

  1. Direct Detection Electron Energy-Loss Spectroscopy: A Method to Push the Limits of Resolution and Sensitivity.

    Science.gov (United States)

    Hart, James L; Lang, Andrew C; Leff, Asher C; Longo, Paolo; Trevor, Colin; Twesten, Ray D; Taheri, Mitra L

    2017-08-15

    In many cases, electron counting with direct detection sensors offers improved resolution, lower noise, and higher pixel density compared to conventional, indirect detection sensors for electron microscopy applications. Direct detection technology has previously been utilized, with great success, for imaging and diffraction, but potential advantages for spectroscopy remain unexplored. Here we compare the performance of a direct detection sensor operated in counting mode and an indirect detection sensor (scintillator/fiber-optic/CCD) for electron energy-loss spectroscopy. Clear improvements in measured detective quantum efficiency and combined energy resolution/energy field-of-view are offered by counting mode direct detection, showing promise for efficient spectrum imaging, low-dose mapping of beam-sensitive specimens, trace element analysis, and time-resolved spectroscopy. Despite the limited counting rate imposed by the readout electronics, we show that both core-loss and low-loss spectral acquisition are practical. These developments will benefit biologists, chemists, physicists, and materials scientists alike.

  2. Low-Fiber Diet in Limited Bowel Preparation for CT Colonography: Influence on Image Quality and Patient Acceptance

    NARCIS (Netherlands)

    Liedenbaum, Marjolein H.; Denters, Maaike J.; de Vries, Ayso H.; van Ravesteijn, Vincent F.; Bipat, Shandra; Vos, Frans M.; Dekker, Evelien; Stoker, Jaap

    2010-01-01

    OBJECTIVE. The purpose of this study was to determine whether a low-fiber diet is necessary for optimal tagging-only bowel preparation for CT colonography. SUBJECTS AND METHODS. Fifty consecutively enrolled patients received an iodine bowel preparation: 25 patients used a low-fiber diet and 25 used

  3. Facile preparation of surfactant-free Au NPs/RGO/Ni foam for degradation of 4-nitrophenol and detection of hydrogen peroxide

    Science.gov (United States)

    Liu, Y. Y.; Guo, X. L.; Zhao, L.; Zhu, L.; Chen, Z. T.; Chen, J.; Zhang, Y.; Sun, L. T.; Zhao, Y. H.

    2018-06-01

    The application of Au nanoparticles (Au NPs) often requires surface modification with chemical surfactants, which dramatically reduce the surface activity and increase the chemical contamination and cost of Au NPs. In this research, we have developed a novel Au NPs/reduced graphene oxide/Ni foam hybrid (Au NPs/RGO/NiF) by in situ reduction through ascorbic acid and replacement reaction. This method is green, facile and efficient. The Au NPs are free of chemical surfactants and are homogeneously distributed on the surface of the RGO/NiF. The as-prepared Au NPs/RGO/NiF hybrid is uniform, stable and exhibits not only a high reduction efficiency for the reduction of 4-nitrophenol with a catalytic kinetic constant of up to 0.46 min‑1 (0.15 cm3 catalysis) but also a sensitive and selective detection of H2O2 with a detection limit of ∼1.60 μM.

  4. Compact quantum dot-antibody conjugates for FRET immunoassays with subnanomolar detection limits

    Science.gov (United States)

    Mattera, Lucia; Bhuckory, Shashi; Wegner, K. David; Qiu, Xue; Agnese, Fabio; Lincheneau, Christophe; Senden, Tim; Djurado, David; Charbonnière, Loïc J.; Hildebrandt, Niko; Reiss, Peter

    2016-05-01

    A novel two-step approach for quantum dot (QD) functionalization and bioconjugation is presented, which yields ultra-compact, stable, and highly luminescent antibody-QD conjugates suitable for use in FRET immunoassays. Hydrophobic InPZnS/ZnSe/ZnS (emission wavelength: 530 nm), CdSe/ZnS (605 nm), and CdSeTe/ZnS (705 nm) QDs were surface functionalized with zwitterionic penicillamine, enabling aqueous phase transfer under conservation of the photoluminescence properties. Post-functionalization with a heterobifunctional crosslinker, containing a lipoic acid group and a maleimide function, enabled the subsequent coupling to sulfhydryl groups of proteins. This was demonstrated by QD conjugation with fragmented antibodies (F(ab)). The obtained F(ab)-QD conjugates range among the smallest antibody-functionalized nanoprobes ever reported, with a hydrodynamic diameter coating for FRET could be demonstrated by an 6.2 and 2.5 fold improvement of the limit of detection (LOD) for PSA compared to commercially available hydrophilic QDs emitting at 605 and 705 nm, respectively. While the commercial QDs contain identical inorganic cores responsible for their fluorescence, they are coated with a comparably thick amphiphilic polymer layer leading to much larger hydrodynamic diameters (>26 nm without biomolecules). The LODs of 0.8 and 3.7 ng mL-1 obtained in 50 μL serum samples are below the clinical cut-off level of PSA (4 ng mL-1) and demonstrate their direct applicability in clinical diagnostics.A novel two-step approach for quantum dot (QD) functionalization and bioconjugation is presented, which yields ultra-compact, stable, and highly luminescent antibody-QD conjugates suitable for use in FRET immunoassays. Hydrophobic InPZnS/ZnSe/ZnS (emission wavelength: 530 nm), CdSe/ZnS (605 nm), and CdSeTe/ZnS (705 nm) QDs were surface functionalized with zwitterionic penicillamine, enabling aqueous phase transfer under conservation of the photoluminescence properties. Post

  5. Detection methods for legionellae. Possibilities and limitations of detection methods; Niet alle detectiemethoden geschikt voor legionellagroei. Mogelijkheden en beperkingen detectiemethoden

    Energy Technology Data Exchange (ETDEWEB)

    Scheffer, W.

    2011-06-15

    This article provides an overview of existing and new methods for detecting legionella in water. It offers insight in the characteristics and applications of existing and new detection methods. However, it is impossible to assess the value of alternative methods at the moment. That will require additional research. [Dutch] Een overzicht is gemaakt van bestaande en nieuwe methoden om legionella in water aan te tonen. Daarmee wordt inzicht verkregen in de kenmerken en toepassingsmogelijkheden van bestaande en nieuwe detectiemethoden. De waarde van alternatieve methoden in een installatie kan echter nog niet worden beoordeeld. Daarvoor is nader onderzoek nodig.

  6. Detection of cytomegalovirus in blood donors by PCR using the digene SHARP signal system assay: effects of sample preparation and detection methodology.

    OpenAIRE

    Krajden, M; Shankaran, P; Bourke, C; Lau, W

    1996-01-01

    Cytomegalovirus (CMV) is an important cause of transfusion-associated morbidity and mortality; however, only 0.4 to 12% of the blood products obtained from seropositive blood donors transmit infection. The effects of three commercially available whole-blood sample preparation kits on the detection of CMV PCR products by a semiquantitative adaptation of the Digene SHARP Signal System Assay (DSSSA) in samples from volunteer blood donors was assessed. Of 101 samples from seropositive blood donor...

  7. Low-Cost 3D Printers Enable High-Quality and Automated Sample Preparation and Molecular Detection.

    Directory of Open Access Journals (Sweden)

    Kamfai Chan

    Full Text Available Most molecular diagnostic assays require upfront sample preparation steps to isolate the target's nucleic acids, followed by its amplification and detection using various nucleic acid amplification techniques. Because molecular diagnostic methods are generally rather difficult to perform manually without highly trained users, automated and integrated systems are highly desirable but too costly for use at point-of-care or low-resource settings. Here, we showcase the development of a low-cost and rapid nucleic acid isolation and amplification platform by modifying entry-level 3D printers that cost between $400 and $750. Our modifications consisted of replacing the extruder with a tip-comb attachment that houses magnets to conduct magnetic particle-based nucleic acid extraction. We then programmed the 3D printer to conduct motions that can perform high-quality extraction protocols. Up to 12 samples can be processed simultaneously in under 13 minutes and the efficiency of nucleic acid isolation matches well against gold-standard spin-column-based extraction technology. Additionally, we used the 3D printer's heated bed to supply heat to perform water bath-based polymerase chain reactions (PCRs. Using another attachment to hold PCR tubes, the 3D printer was programmed to automate the process of shuttling PCR tubes between water baths. By eliminating the temperature ramping needed in most commercial thermal cyclers, the run time of a 35-cycle PCR protocol was shortened by 33%. This article demonstrates that for applications in resource-limited settings, expensive nucleic acid extraction devices and thermal cyclers that are used in many central laboratories can be potentially replaced by a device modified from inexpensive entry-level 3D printers.

  8. Low-Cost 3D Printers Enable High-Quality and Automated Sample Preparation and Molecular Detection

    Science.gov (United States)

    Chan, Kamfai; Coen, Mauricio; Hardick, Justin; Gaydos, Charlotte A.; Wong, Kah-Yat; Smith, Clayton; Wilson, Scott A.; Vayugundla, Siva Praneeth; Wong, Season

    2016-01-01

    Most molecular diagnostic assays require upfront sample preparation steps to isolate the target’s nucleic acids, followed by its amplification and detection using various nucleic acid amplification techniques. Because molecular diagnostic methods are generally rather difficult to perform manually without highly trained users, automated and integrated systems are highly desirable but too costly for use at point-of-care or low-resource settings. Here, we showcase the development of a low-cost and rapid nucleic acid isolation and amplification platform by modifying entry-level 3D printers that cost between $400 and $750. Our modifications consisted of replacing the extruder with a tip-comb attachment that houses magnets to conduct magnetic particle-based nucleic acid extraction. We then programmed the 3D printer to conduct motions that can perform high-quality extraction protocols. Up to 12 samples can be processed simultaneously in under 13 minutes and the efficiency of nucleic acid isolation matches well against gold-standard spin-column-based extraction technology. Additionally, we used the 3D printer’s heated bed to supply heat to perform water bath-based polymerase chain reactions (PCRs). Using another attachment to hold PCR tubes, the 3D printer was programmed to automate the process of shuttling PCR tubes between water baths. By eliminating the temperature ramping needed in most commercial thermal cyclers, the run time of a 35-cycle PCR protocol was shortened by 33%. This article demonstrates that for applications in resource-limited settings, expensive nucleic acid extraction devices and thermal cyclers that are used in many central laboratories can be potentially replaced by a device modified from inexpensive entry-level 3D printers. PMID:27362424

  9. Direct and simultaneous detection of organic and inorganic ingredients in herbal powder preparations by Fourier transform infrared microspectroscopic imaging.

    Science.gov (United States)

    Chen, Jian-Bo; Sun, Su-Qin; Tang, Xu-Dong; Zhang, Jing-Zhao; Zhou, Qun

    2016-08-05

    Herbal powder preparation is a kind of widely-used herbal product in the form of powder mixture of herbal ingredients. Identification of herbal ingredients is the first and foremost step in assuring the quality, safety and efficacy of herbal powder preparations. In this research, Fourier transform infrared (FT-IR) microspectroscopic identification method is proposed for the direct and simultaneous recognition of multiple organic and inorganic ingredients in herbal powder preparations. First, the reference spectrum of characteristic particles of each herbal ingredient is assigned according to FT-IR results and other available information. Next, a statistical correlation threshold is determined as the lower limit of correlation coefficients between the reference spectrum and a larger number of calibration characteristic particles. After validation, the reference spectrum and correlation threshold can be used to identify herbal ingredient in mixture preparations. A herbal ingredient is supposed to be present if correlation coefficients between the reference spectrum and some sample particles are above the threshold. Using this method, all kinds of herbal materials in powder preparation Kouqiang Kuiyang San are identified successfully. This research shows the potential of FT-IR microspectroscopic identification method for the accurate and quick identification of ingredients in herbal powder preparations. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. A program for the a priori evaluation of detection limits in instrumental neutron activation analysis using a SLOWPOKE II reactor

    International Nuclear Information System (INIS)

    Galinier, J.L.; Zikovsky, L.

    1982-01-01

    A program that permits the a priori calculation of detection limits in monoelemental matrices, adapted to instrumental neutron activation analysis using a SLOWPOKE II reactor, is described. A simplified model of the gamma spectra is proposed. Products of (n,p) and (n,α) reactions induced by the fast components of the neutron flux that accompanies the thermal flux at the level of internal irradiation sites in the reactor have been included in the list of interfering radionuclides. The program calculates in a systematic way the detection limits of 66 elements in an equal number of matrices using 153 intermediary radionuclides. Experimental checks carried out with silicon (for short lifetimes) and aluminum and magnesium (for intermediate lifetimes) show satisfactory agreement with the calculations. These results show in particular the importance of the contribution of the (n,p) and (n,α) reactions in the a priori evaluation of detection limits with a SLOWPOKE type reactor [fr

  11. Calculating exclusion limits for weakly interacting massive particle direct detection experiments without background subtraction

    International Nuclear Information System (INIS)

    Green, Anne M.

    2002-01-01

    Competitive limits on the weakly interacting massive particle (WIMP) spin-independent scattering cross section are currently being produced by 76 Ge detectors originally designed to search for neutrinoless double beta decay, such as the Heidelberg-Moscow and IGEX experiments. In the absence of background subtraction, limits on the WIMP interaction cross section are set by calculating the upper confidence limit on the theoretical event rate, given the observed event rate. The standard analysis technique involves calculating the 90% upper confidence limit on the number of events in each bin, and excluding any set of parameters (WIMP mass and cross section) which produces a theoretical event rate for any bin which exceeds the 90% upper confidence limit on the event rate for that bin. We show that, if there is more than one energy bin, this produces exclusion limits that are actually at a lower degree of confidence than 90%, and are hence erroneously tight. We formulate criteria which produce true 90% confidence exclusion limits in these circumstances, including calculating the individual bin confidence limit for which the overall probability that no bins exceed this confidence limit is 90% and calculating the 90% minimum confidence limit on the number of bins which exceed their individual bin 90% confidence limits. We then compare the limits on the WIMP cross section produced by these criteria with those found using the standard technique, using data from the Heidelberg-Moscow and IGEX experiments

  12. Carbon quantum dots prepared with polyethyleneimine as both reducing agent and stabilizer for synthesis of Ag/CQDs composite for Hg{sup 2+} ions detection

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ting; Dong, Jiang Xue; Liu, Shi Gang; Li, Na; Lin, Shu Min; Fan, Yu Zhu [Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, No.2 Tiansheng Road, BeiBei District, Chongqing 400715 (China); Lei, Jing Lie [School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China); Luo, Hong Qun, E-mail: luohq@swu.edu.cn [Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, No.2 Tiansheng Road, BeiBei District, Chongqing 400715 (China); Li, Nian Bing, E-mail: linb@swu.edu.cn [Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, No.2 Tiansheng Road, BeiBei District, Chongqing 400715 (China)

    2017-01-15

    Highlights: • The carbon quantum dots (CQDs) synthesized with PEI showed an extraordinary reducibility. • The Ag/CQDs composite was prepared by using CQDs as reducing and stabilizing agent. • A simple Ag/CQDs composite-based dual-signal probe was provided for Hg{sup 2+} detection. • The proposed strategy shows a potential for detecting Hg{sup 2+} in real water samples. - Abstract: A stable silver nanoparticles/carbon quantum dots (Ag/CQDs) composite was prepared by using CQDs as reducing and stabilizing agent. The CQDs synthesized with polyethyleneimine (PEI) showed an extraordinary reducibility. When Hg{sup 2+} was presented in the Ag/CQDs composite solution, a color change from yellow to colorless was observed, accompanied by a shift of surface plasmon resonance (SPR) band and decrease in absorbance of the Ag/CQDs composite. On the basis of the further studies on TEM, XPS and XRD analysis, the possible mechanism is attributed to the formation of a silver-mercury amalgam. Hence, a two dimensional sensing platform for Hg{sup 2+} detection was constructed upon the Ag/CQDs composite. Based on the change of absorbance, a good linear relationship was obtained from 0.5 to 50 μM for Hg{sup 2+}. And the limit of detection for Hg{sup 2+} was as low as 85 nM, representing high sensitivity to Hg{sup 2+}. More importantly, the proposed method also exhibits a good selectivity toward Hg{sup 2+} over other metal ions. Besides, this strategy demonstrates practicability for the detection of Hg{sup 2+} in real water samples with satisfactory results.

  13. Detection limits should be a thing of the past in gamma-ray spectrometry in general as well as in neutron activation analysis

    NARCIS (Netherlands)

    Blaauw, Menno

    2016-01-01

    In gamma-ray spectrometry with high-resolution detectors, full-energy peaks are often to be detected by a peak-search algorithm, with a threshold for detection. Detection limits can be derived from this. Detection limits are often computed along with measured activities or concentrations. When an

  14. Geodesy cannot presently detect the up-dip limit of frictional locking on megathrusts

    Science.gov (United States)

    Almeida, R. V.; Lindsey, E. O.; Bradley, K.; Hubbard, J.; Sathiakumar, S.; Malick, R.; Hill, E.

    2017-12-01

    Most discussions of interseismic behavior on megathrust faults focus on whether they are frictionally locked or creeping. Unfortunately, many geodetic studies of subduction zone megathrusts equate fault coupling with frictional locking. This comparison is not appropriate, as one reflects the physical properties of the fault, and the other reflects the kinematics of the fault. Much of the uncertainty about slip behavior is because in subduction zones, the shallow part of the fault is far from land, and therefore creep is not detectable by land-based GPS. Published coupling maps of subduction zone megathrusts often assume a low coupling ratio near the trench, updip from fully coupled regions. Yet, if the megathrust attains a coupling ratio of 1 anywhere on the fault (i.e., the hanging wall is moving with the same velocity as the footwall), a lower value of coupling updip of this location requires interseismic extension at a rate proportional to the decrease (Wang and Dixon, 2004). We argue that the shallow region of megathrusts lie in updip stress shadows, and do not (except under rare circumstances) experience appropriate driving forces to cause significant creep during the interseismic period. Therefore it may not be possible to determine whether these regions are frictionally locked by examining interseismic geodetic records. We demonstrate this effect using a boundary element model with rate-strengthening friction and a simplified subduction zone geometry. We show that a coupling value of zero at the trench is physically unrealistic even if only a small portion of the downdip fault zone is locked. The maximum creep at the trench depends on the width of the transition of the frictionally locked zone, but should be small (<30% of plate rate) under most circumstances. During the interseismic period, even if the shallow parts of megathrusts are frictionally unlocked, creep is likely smaller than the resolution of current seafloor geodetic techniques (which is

  15. A low-volume polyethylene glycol solution was associated with an increased suboptimal bowel preparation rate but had similar recommendations for an early repeat colonoscopy, procedure times, and adenoma detection rates.

    Directory of Open Access Journals (Sweden)

    Sam C Hankins

    Full Text Available Low-volume polyethylene glycol (PEG bowel preparations are better tolerated by patients than high-volume preparations and may achieve similar preparation quality. However, there is little data comparing their effects on a recommendation for an early repeat colonoscopy (because of a suboptimal preparation, procedure times, adenoma detection rate (ADR, and advanced adenoma detection rate (AADR.This is a retrospective cohort study of outpatient colonoscopies performed during a one-year period at a single academic medical center in which low-volume MoviPrep® (n = 1841 or high-volume Colyte® (n = 1337 was used. All preparations were split-dosed. Appropriate covariates were included in regression models assessing suboptimal preparation quality (fair, poor, or inadequate, procedure times, recommendation for an early repeat colonoscopy, ADR, and AADR.MoviPrep® was associated with an increase in having a suboptimal bowel preparation (OR 1.36; 95% CI: 1.06-1.76, but it was not associated with differences in insertion (p = 0.43, withdrawal (p = 0.22, or total procedure times (p = 0.10. The adjusted percentage with a suboptimal preparation was 11.7% for patients using MoviPrep® and 8.8% for patients using Colyte®. MoviPrep® was not associated with a significant difference in overall ADR (OR 0.93; 95% CI: 0.78-1.11, AADR (OR 1.18; 95% CI: 0.87-1.62, or recommendation for early repeat colonoscopy (OR 1.16; 95% CI: 0.72-1.88.MoviPrep® was associated with a small absolute increase in having a suboptimal preparation, but did not affect recommendations for an early repeat colonoscopy, procedure times, or adenoma detection rates. Mechanisms to reduce financial barriers limiting low-volume preparations should be considered because of their favorable tolerability profile.

  16. Fabrication of Stretchable Copper Coated Carbon Nanotube Conductor for Non-Enzymatic Glucose Detection Electrode with Low Detection Limit and Selectivity

    Directory of Open Access Journals (Sweden)

    Dawei Jiang

    2018-03-01

    Full Text Available The increasing demand for wearable glucose sensing has stimulated growing interest in stretchable electrodes. The development of the electrode materials having large stretchability, low detection limit, and good selectivity is the key component for constructing high performance wearable glucose sensors. In this work, we presented fabrication of stretchable conductor based on the copper coated carbon nanotube sheath-core fiber, and its application as non-enzymatic electrode for glucose detection with high stretchability, low detection limit, and selectivity. The sheath-core fiber was fabricated by coating copper coated carbon nanotube on a pre-stretched rubber fiber core followed by release of pre-stretch, which had a hierarchically buckled structure. It showed a small resistance change as low as 27% as strain increasing from 0% to 500% strain, and a low resistance of 0.4 Ω·cm−1 at strain of 500%. This electrode showed linear glucose concentration detection in the range between 0.05 mM and 5 mM and good selectivity against sucrose, lactic acid, uric acid, acrylic acid in phosphate buffer saline solution, and showed stable signal in high salt concentration. The limit of detection (LOD was 0.05 mM, for the range of 0.05–5 mM, the sensitivity is 46 mA·M−1. This electrode can withstand large strain of up to 60% with negligible influence on its performance.

  17. Rapid Methods for the Detection of Foodborne Bacterial Pathogens: Principles, Applications, Advantages and Limitations

    Directory of Open Access Journals (Sweden)

    Law eJodi Woan-Fei

    2015-01-01

    Full Text Available The incidence of foodborne diseases has increased over the years and resulted in major public health problem globally. Foodborne pathogens can be found in various foods and it is important to detect foodborne pathogens to provide safe food supply and to prevent foodborne diseases. The conventional methods used to detect foodborne pathogen are time consuming and laborious. Hence, a variety of methods have been developed for rapid detection of foodborne pathogens as it is required in many food analyses. Rapid detection methods can be categorized into nucleic acid-based, biosensor-based and immunological-based methods. This review emphasizes on the principles and application of recent rapid methods for the detection of foodborne bacterial pathogens. Detection methods included are simple polymerase chain reaction (PCR, multiplex PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA, loop-mediated isothermal amplification (LAMP and oligonucleotide DNA microarray which classified as nucleic acid-based methods; optical, electrochemical and mass-based biosensors which classified as biosensor-based methods; enzyme-linked immunosorbent assay (ELISA and lateral flow immunoassay which classified as immunological-based methods. In general, rapid detection methods are generally time-efficient, sensitive, specific and labor-saving. The developments of rapid detection methods are vital in prevention and treatment of foodborne diseases.

  18. Preparation and surface functionalisation of poly(styrene maleimide) nanoparticles for bacterial detection

    CSIR Research Space (South Africa)

    Barnard, A

    2012-10-01

    Full Text Available .kashan.co.za] INTRODUCTION The detection of bacteria in water is essential for the prevention of water-borne disease outbreaks. Conventionally, culturing methods are used to detect bacteria in water, whereby the number of bacteria present in a sample is multiplied to a... to the particle surfaces for attachment of fluorescent markers and antibodies. Figure 1: Process diagram of proposed development method of nanoparticles for bacteria detection Particle characterisation was performed with transmission electron microscopy (TEM...

  19. Current methods of handling less-than-detectable measurements and detection limits in statistical analysis of environmental data

    International Nuclear Information System (INIS)

    Hertzler, C.L.; Atwood, C.L.; Harris, G.A.

    1989-09-01

    A search was made of statistical literature that might be applicable in environmental assessment contexts, when some of the measured quantities are reported as less than detectable (LTD). Over 60 documents were reviewed, and the findings are described in this report. The methodological areas considered are parameter estimation (point estimates and confidence intervals), tolerance intervals and prediction intervals, regression, trend analysis, comparisons of populations (including two-sample comparisons and analysis of variance), and goodness of fit tests. The conclusions are summarized at the end of the report. 68 refs., 1 tab

  20. Clinical Application of Picodroplet Digital PCR Technology for Rapid Detection of EGFR T790M in Next-Generation Sequencing Libraries and DNA from Limited Tumor Samples.

    Science.gov (United States)

    Borsu, Laetitia; Intrieri, Julie; Thampi, Linta; Yu, Helena; Riely, Gregory; Nafa, Khedoudja; Chandramohan, Raghu; Ladanyi, Marc; Arcila, Maria E

    2016-11-01

    Although next-generation sequencing (NGS) is a robust technology for comprehensive assessment of EGFR-mutant lung adenocarcinomas with acquired resistance to tyrosine kinase inhibitors, it may not provide sufficiently rapid and sensitive detection of the EGFR T790M mutation, the most clinically relevant resistance biomarker. Here, we describe a digital PCR (dPCR) assay for rapid T790M detection on aliquots of NGS libraries prepared for comprehensive profiling, fully maximizing broad genomic analysis on limited samples. Tumor DNAs from patients with EGFR-mutant lung adenocarcinomas and acquired resistance to epidermal growth factor receptor inhibitors were prepared for Memorial Sloan-Kettering-Integrated Mutation Profiling of Actionable Cancer Targets sequencing, a hybrid capture-based assay interrogating 410 cancer-related genes. Precapture library aliquots were used for rapid EGFR T790M testing by dPCR, and results were compared with NGS and locked nucleic acid-PCR Sanger sequencing (reference high sensitivity method). Seventy resistance samples showed 99% concordance with the reference high sensitivity method in accuracy studies. Input as low as 2.5 ng provided a sensitivity of 1% and improved further with increasing DNA input. dPCR on libraries required less DNA and showed better performance than direct genomic DNA. dPCR on NGS libraries is a robust and rapid approach to EGFR T790M testing, allowing most economical utilization of limited material for comprehensive assessment. The same assay can also be performed directly on any limited DNA source and cell-free DNA. Copyright © 2016 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.

  1. Evaluation of a manual DNA extraction protocol and an isothermal amplification assay for detecting HIV-1 DNA from dried blood spots for use in resource-limited settings.

    Science.gov (United States)

    Jordan, Jeanne A; Ibe, Christine O; Moore, Miranda S; Host, Christel; Simon, Gary L

    2012-05-01

    In resource-limited settings (RLS) dried blood spots (DBS) are collected on infants and transported through provincial laboratories to a central facility where HIV-1 DNA PCR testing is performed using specialized equipment. Implementing a simpler approach not requiring such equipment or skilled personnel could allow the more numerous provincial laboratories to offer testing, improving turn-around-time to identify and treat infected infants sooner. Assess performances of a manual DNA extraction method and helicase-dependent amplification (HDA) assay for detecting HIV-1 DNA from DBS. 60 HIV-1 infected adults were enrolled, blood samples taken and DBS made. DBS extracts were assessed for DNA concentration and beta globin amplification using PCR and melt-curve analysis. These same extracts were then tested for HIV-1 DNA using HDA and compared to results generated by PCR and pyrosequencing. Finally, HDA limit of detection (LOD) studies were performed using DBS extracts prepared with known numbers of 8E5 cells. The manual extraction protocol consistently yielded high concentrations of amplifiable DNA from DBS. LOD assessment demonstrated HDA detected ∼470 copies/ml of HIV-1 DNA extracts in 4/4 replicates. No statistical difference was found using the McNemar's test when comparing HDA to PCR for detecting HIV-1 DNA from DBS. Using just a magnet, heat block and pipettes, the manual extraction protocol and HDA assay detected HIV-1 DNA from DBS at levels that would be useful for early infant diagnosis. Next steps will include assessing HDA for non-B HIV-1 subtypes recognition and comparison to Roche HIV-1 DNA v1.5 PCR assay. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Evaluation of the limits of visual detection of image misregistration in a brain fluorine-18 fluorodeoxyglucose PET-MRI study

    International Nuclear Information System (INIS)

    Wong, J.C.H.; Studholme, C.; Hawkes, D.J.; Maisey, M.N.

    1997-01-01

    In routine clinical work, registration accuracy is assessed by visual inspection. However, the accuracy of visual assessment of registration has not been evaluated. This study establishes the limits of visual detection of misregistration in a registered brain fluorine-18 fluorodeoxyglucose positron emission tomography to magnetic resonance image volume. The ''best'' registered image volume was obtained by automatic registration using mutual information optimization. Translational movements by 1 mm, 2 mm, 3 mm and 4 mm, and rotational movements by 1 , 2 , 3 and 4 in the positive and negative directions in the x- (lateral), y- (anterior-posterior) and z- (axial) axes were introduced to this standard. These 48 images plus six ''best'' registered images were presented in random sequence to five observers for visual categorization of registration accuracy. No observer detected a definite misregistration in the ''best'' registered image. Evaluation for inter-observer variation using observer pairings showed a high percentage of agreement in assigned categories for both translational and rotational misregistrations. Assessment of the limits of detection of misregistration showed that a 2-mm translational misregistration was detectable by all observers in the x- and y-axes and 3-mm translational misregistration in the z-axis. With rotational misregistrations, rotation around the z-axis was detectable by all at 2 rotation whereas rotation around the y-axis was detected at 3-4 . Rotation around the x-axis was not symmetric with a positive rotation being identified at 2 whereas negative rotation was detected by all only at 4 . Therefore, visual analysis appears to be a sensitive and practical means to assess image misregistration accuracy. The awareness of the limits of visual detection of misregistration will lead to increase care when evaluating registration quality in both research and clinical settings. (orig.). With 6 figs., 3 tabs

  3. Detection and quantification limits: basic concepts, international harmonization, and outstanding ('low-level') issues

    International Nuclear Information System (INIS)

    Currie, L.A.

    2004-01-01

    A brief review is given of concepts, basic definitions, and terminology for metrological detection and quantification capabilities, representing harmonized recommendations and norms of the International Union of Pure and Applied Chemistry (IUPAC) and the International Organization for Standardization (ISO), respectively. Treatment of the (low-level) blank and variance function are discussed in some detail, together with special problems arising with detection decisions and the reporting of low-level data. Key references to the international documents follow, as well as specialized references addressing very low-level counting data, skewed environmental blank distributions, and multiple and multivariate detection decisions

  4. The detection and stabilisation of limit cycle for deterministic finite automata

    Science.gov (United States)

    Han, Xiaoguang; Chen, Zengqiang; Liu, Zhongxin; Zhang, Qing

    2018-04-01

    In this paper, the topological structure properties of deterministic finite automata (DFA), under the framework of the semi-tensor product of matrices, are investigated. First, the dynamics of DFA are converted into a new algebraic form as a discrete-time linear system by means of Boolean algebra. Using this algebraic description, the approach of calculating the limit cycles of different lengths is given. Second, we present two fundamental concepts, namely, domain of attraction of limit cycle and prereachability set. Based on the prereachability set, an explicit solution of calculating domain of attraction of a limit cycle is completely characterised. Third, we define the globally attractive limit cycle, and then the necessary and sufficient condition for verifying whether all state trajectories of a DFA enter a given limit cycle in a finite number of transitions is given. Fourth, the problem of whether a DFA can be stabilised to a limit cycle by the state feedback controller is discussed. Criteria for limit cycle-stabilisation are established. All state feedback controllers which implement the minimal length trajectories from each state to the limit cycle are obtained by using the proposed algorithm. Finally, an illustrative example is presented to show the theoretical results.

  5. DNA isolation protocols affect the detection limit of PCR approaches of bacteria in samples from the human gastrointestinal tract

    NARCIS (Netherlands)

    Zoetendal, E.G.; Ben-Amor, K.; Akkermans, A.D.L.; Abee, T.; Vos, de W.M.

    2001-01-01

    A major concern in molecular ecological studies is the lysis efficiency of different bacteria in a complex ecosystem. We used a PCR-based 16S rDNA approach to determine the effect of two DNA isolation protocols (i.e. the bead beating and Triton-X100 method) on the detection limit of seven

  6. Re-evaluation of groundwater monitoring data for glyphosate and bentazone by taking detection limits into account

    DEFF Research Database (Denmark)

    Hansen, Claus Toni; Ritz, Christian; Gerhard, Daniel

    2015-01-01

    .e. samples with concentrations below the detection limit, as left-censored observations. The median calculated pesticide concentrations are shown to be reduced 10(4) to 10(5) fold for two representative herbicides (glyphosate and bentazone) relative to the median concentrations based upon observations above...

  7. Analysis of uncertainties and detection limits for the double measurement method of {sup 90}Sr and {sup 89}Sr

    Energy Technology Data Exchange (ETDEWEB)

    Herranz, M., E-mail: m.herranz@ehu.es [Department of Nuclear Engineering and Fluid Mechanics, University of the Basque Country (UPV/EHU), Alameda de Urquijo s/n 48013 Bilbao (Spain); Idoeta, R.; Legarda, F. [Department of Nuclear Engineering and Fluid Mechanics, University of the Basque Country (UPV/EHU), Alameda de Urquijo s/n 48013 Bilbao (Spain)

    2011-08-15

    The determination process of the {sup 90}Sr and {sup 89}Sr contents in a sample, although it involves their radiochemical isolation, results always in a complex measurement process due to the interferences among their respective beta emissions and also among those of the daughter of {sup 90}Sr, {sup 90}Y, a beta emitter as well. In this paper, the process consisting in a double measurement method after the Sr radiochemical isolation is analyzed, developing the formulae to obtain activity concentrations, uncertainties and detection limits. A study of the trend of uncertainties and detection limits as function of the time in which the first measurement since the isolation is done, the delay between the two measurements and the activity concentration of each strontium isotope in the sample is carried out as well. Results show that with a very precise determination of the times involved in the whole process (isolation, measurement and duration of measurements) this method permits a reliable assessment of both strontium radioisotopes. The quicker the first measurement since the isolation is done and the longer the delay between measurements is chosen, the lower are the detection limits and the uncertainties of the activities obtained. - Highlights: > The double measurement method for {sup 90}Sr and {sup 89}Sr determination is analysed. > Uncertainties and detection limits are determined and their dependences studied. > Proposals for the optimization of the method are given.

  8. 40 CFR Appendix C to Part 425 - Definition and Procedure for the Determination of the Method Detection Limit 1

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Definition and Procedure for the Determination of the Method Detection Limit 1 C Appendix C to Part 425 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS LEATHER TANNING AND FINISHING POINT SOURCE...

  9. Consistent Practices for Characterizing the Detection Limits of Fracture Critical Metallic Component Inspection Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA-STD-5009 requires that successful flaw detection by NDE methods be statistically qualified for use on fracture critical metallic components using Probability of...

  10. Limitations and Strengths of the Fourier Transform Method to Detect Accelerating Targets

    National Research Council Canada - National Science Library

    Thayaparan, Thayananthan

    2000-01-01

    .... In using a Pulse Doppler Radar to detect a non-accelerating target in additive white Gaussian noise and to estimate its radial velocity, the Fourier method provides an output signal-to-noise ratio (SNR...

  11. Soil and Water – What is Detectable through Microbiological Sample Preparation Techniques

    Science.gov (United States)

    The concerns of a potential terrorist’s use of biological agents in soil and ground water are articulated by comparisons to major illnesses in this Country involving contaminated drinking water sources. Objectives are focused on the importance of sample preparation in the rapid, ...

  12. Detection and identification of "new" beta-agonists in black-market preparations

    NARCIS (Netherlands)

    van Ginkel LA; Stephany RW; van Rossum HJ; Visser T; den Engelsman T; de Jong APJM; Jacquemijns M; Zomer G

    1992-01-01

    In several "black-market" used for growth promotion preparations new compounds were found belonging to the group of N-phenylethanolamines with structures very similar to compounds known to be used for veal calf and cattle production, the so called beta-agonists. The two most important

  13. Local Preparation and Evaluation of Double - antibody Liquid Phase Radioimmunoassay System for Detection of Human Testosterone

    International Nuclear Information System (INIS)

    Shafik, H.M.; Sallam, Kh.M.; Ebeid, N.H.; Elshaer, M.R.; Elshae, M.R.

    2016-01-01

    Preparation, evaluation and optimization of testosterone radioimmunoassay (RIA) system using liquid phase double antibody is considered to be the main objective. Three primary components were prepared and characterized to obtain valid and accurate system. These components were polyclonal testosterone antibody, the "1"2"5I-testosterone tracer and set of testosterone standards. The production of polyclonal testosterone antibody was undertaken by immunizing two groups of females white New-Zealand rabbits with testosterone-3-(O-carboxy methyloxime): BSA as immunogen through primary immunization and five boosters. Both R 1 and R 4 gave anti-serum has a high immuno reactivity. The preparation of "1"2"5I-testosterone tracer was carried out using three different conjugates (testosterone-3-TME, testosterone-3-histamine and testosterone-3-BSA) by electrophilic substitution mechanism using chloramine-T as oxidizing agent. Tracers were characterized in terms of radiochemical yield %, radiochemical purity %, specific activity and immuno reactivity. A set of testosterone standards were prepared using highly purified testosterone antigen. Optimization and validation tests of the local liquid phase RIA system were carried out. In conclusion, the results showed that, the local testosterone RIA system is sensitive, specific and accurate with significant cost reduction in comparison with commertial kit and extended use of the method for routine investigation of variety of diseases especially hypogonadism and associated male infertility

  14. Rapid Detection Strategies for the Global Threat of Zika Virus: Current State, New Hypotheses and Limitations

    Directory of Open Access Journals (Sweden)

    Shruti Shukla

    2016-10-01

    Full Text Available The current scenario regarding the widespread Zika virus (ZIKV has resulted in numerous diagnostic studies, specifically in South America and in locations where there is frequent entry of travelers returning from ZIKV-affected areas, including pregnant women with or without clinical symptoms of ZIKV infection. The World Health Organization, WHO, announced that millions of cases of ZIKV are likely to occur in the United States of America in the near future. This situation has created an alarming public health emergency of international concern requiring the detection of this life-threatening viral candidate due to increased cases of newborn microcephaly associated with ZIKV infection. Hence, this review reports possible methods and strategies for the fast and reliable detection of ZIKV with particular emphasis on current updates, knowledge and new hypotheses that might be helpful for medical professionals in poor and developing countries that urgently need to address this problem. In particular, we emphasize liposome-based biosensors. Although these biosensors are currently among the less popular tools for human disease detection, they have become useful tools for the screening and detection of pathogenic bacteria, fungi and viruses because of their versatile advantageous features compared to other sensing devices. This review summarizes the currently available methods employed for the rapid detection of ZIKV and suggests an innovative approach involving the application of a liposome-based hypothesis for the development of new strategies for ZIKV detection and their use as effective biomedicinal tools.

  15. Limit of detection for the determination of Pt in biological material by RNAA using electrolytic separation of gold

    International Nuclear Information System (INIS)

    Xilei, L.; Heydorn, K.; Rietz, B.

    1992-01-01

    Neutron activation analysis based on the 199 Au indicator for platinum requires the separation of gold at high radiochemical purity. The limit of detection is strongly affected by the presence of gold; with a gold content of 50 pg/g, irradiating for 5 days at 5*10 13 n/cm 2 is needed to achieve a limit of detection of approximately 30 pg/g. In this case the nuclear interference from gold will exceeded the level of platium by several orders of magnitude and has to be determined with exceedingly high precision. Preliminary results for SRM 1577 Bovine Liver with 95% yield gave consistent results for Au, but Pt could not be detected. (author) 23 refs.; 3 figs.; 4 tabs

  16. Ultrasensitive and simultaneous detection of hydroquinone, catechol and resorcinol based on the electrochemical co-reduction prepared Au-Pd nanoflower/reduced graphene oxide nanocomposite

    International Nuclear Information System (INIS)

    Chen, Yuan; Liu, Xiaoying; Zhang, Si; Yang, Liuqing; Liu, Meiling; Zhang, Youyu; Yao, Shouzhuo

    2017-01-01

    A simple and efficient eletrochemical sensing platform for simultaneous detection of hydroquinone (HQ), catechol (CC) and resorcinol (RC) based on the Au-Pd bimetallic and graphene is described in this paper. The Au-Pd reduced graphene oxide (Au-Pd NF/rGO) was prepared by the electrochemical co-reduction deposition via cyclic voltammetry method (CV). The Au-Pd NF/rGO nanocomposite was examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and electrochemical methods CV and differential pulse voltammety (DPV) study showed that the three dihydroxybenzene isomers can be catalytically oxidized and discriminated simultaneously on the Au-Pd NF/rGO/GCE. The presence of Pd makes the performance of the sensor superior to that of in the absence of it. Owing to the integrated superior conductivity and excellent catalytic property of Au-Pd NF/rGO, the sensitive and simultaneous detection of HQ, CC and RC was realized in the individual or triple-components solution based on the as proposed Au-Pd NF/rGO/GCE, which shows wide linear range and low detection limit. The detection of them in tap water, river water and lake water were also successfully performed and good recovery was obtained.

  17. Systematic optimization of multiplex zymography protocol to detect active cathepsins K, L, S, and V in healthy and diseased tissue: compromise among limits of detection, reduced time, and resources.

    Science.gov (United States)

    Dumas, Jerald E; Platt, Manu O

    2013-07-01

    Cysteine cathepsins are a family of proteases identified in cancer, atherosclerosis, osteoporosis, arthritis, and a number of other diseases. As this number continues to rise, so does the need for low cost, broad use quantitative assays to detect their activity and can be translated to the clinic in the hospital or in low resource settings. Multiplex cathepsin zymography is one such assay that detects subnanomolar levels of active cathepsins K, L, S, and V in cell or tissue preparations observed as clear bands of proteolytic activity after gelatin substrate SDS-PAGE with conditions optimal for cathepsin renaturing and activity. Densitometric analysis of the zymogram provides quantitative information from this low cost assay. After systematic modifications to optimize cathepsin zymography, we describe reduced electrophoresis time from 2 h to 10 min, incubation assay time from overnight to 4 h, and reduced minimal tissue protein necessary while maintaining sensitive detection limits; an evaluation of the pros and cons of each modification is also included. We further describe image acquisition by Smartphone camera, export to Matlab, and densitometric analysis code to quantify and report cathepsin activity, adding portability and replacing large scale, darkbox imaging equipment that could be cost prohibitive in limited resource settings.

  18. Systematic optimization of multiplex zymography protocol to detect active cathepsins K, L, S, and V in healthy and diseased tissue: compromise between limits of detection, reduced time, and resources

    Science.gov (United States)

    Dumas, Jerald E.; Platt, Manu O.

    2013-01-01

    Cysteine cathepsins are a family of proteases identified in cancer, atherosclerosis, osteoporosis, arthritis and a number of other diseases. As this number continues to rise, so does the need for low cost, broad use quantitative assays to detect their activity and can be translated to the clinic in the hospital or in low resource settings. Multiplex cathepsin zymography is one such assay that detects subnanomolar levels of active cathepsins K, L, S, and V in cell or tissue preparations observed as cleared bands of proteolytic activity after gelatin substrate SDS-PAGE with conditions optimal for cathepsin renaturing and activity. Densitometric analysis of the zymogram provides quantitative information from this low cost assay. After systematic modifications to optimize cathepsin zymography, we describe reduced electrophoresis time from 2 hours to 10 minutes, incubation assay time from overnight to 4 hours, and reduced minimal tissue protein necessary while maintaining sensitive detection limits; an evaluation of the pros and cons of each modification is also included. We further describe image acquisition by smartphone camera, export to Matlab, and densitometric analysis code to quantify and report cathepsin activity, adding portability and replacing large scale, darkbox imaging equipment that could be cost prohibitive in limited resource settings. PMID:23532386

  19. Efficient sample preparation method based on solvent-assisted dispersive solid-phase extraction for the trace detection of butachlor in urine and waste water samples.

    Science.gov (United States)

    Aladaghlo, Zolfaghar; Fakhari, Alireza; Behbahani, Mohammad

    2016-10-01

    In this work, an efficient sample preparation method termed solvent-assisted dispersive solid-phase extraction was applied. The used sample preparation method was based on the dispersion of the sorbent (benzophenone) into the aqueous sample to maximize the interaction surface. In this approach, the dispersion of the sorbent at a very low milligram level was achieved by inserting a solution of the sorbent and disperser solvent into the aqueous sample. The cloudy solution created from the dispersion of the sorbent in the bulk aqueous sample. After pre-concentration of the butachlor, the cloudy solution was centrifuged and butachlor in the sediment phase dissolved in ethanol and determined by gas chromatography with flame ionization detection. Under the optimized conditions (solution pH = 7.0, sorbent: benzophenone, 2%, disperser solvent: ethanol, 500 μL, centrifuged at 4000 rpm for 3 min), the method detection limit for butachlor was 2, 3 and 3 μg/L for distilled water, waste water, and urine sample, respectively. Furthermore, the preconcentration factor was 198.8, 175.0, and 174.2 in distilled water, waste water, and urine sample, respectively. Solvent-assisted dispersive solid-phase extraction was successfully used for the trace monitoring of butachlor in urine and waste water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Limits on surface gravities of Kepler planet-candidate host stars from non-detection of solar-like oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Campante, T. L.; Chaplin, W. J.; Handberg, R.; Miglio, A.; Davies, G. R.; Elsworth, Y. P. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Lund, M. N.; Arentoft, T.; Christensen-Dalsgaard, J.; Karoff, C.; Kjeldsen, H.; Lundkvist, M. [Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Huber, D. [NASA Ames Research Center, MS 244-30, Moffett Field, CA 94035 (United States); Hekker, S. [Astronomical Institute, " Anton Pannekoek," University of Amsterdam, Amsterdam (Netherlands); García, R. A. [Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot (France); IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Corsaro, E. [Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Basu, S. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Bedding, T. R. [Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney (Australia); Gilliland, R. L. [Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, University Park, PA 16802 (United States); Kawaler, S. D., E-mail: campante@bison.ph.bham.ac.uk [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); and others

    2014-03-10

    We present a novel method for estimating lower-limit surface gravities (log g) of Kepler targets whose data do not allow the detection of solar-like oscillations. The method is tested using an ensemble of solar-type stars observed in the context of the Kepler Asteroseismic Science Consortium. We then proceed to estimate lower-limit log g for a cohort of Kepler solar-type planet-candidate host stars with no detected oscillations. Limits on fundamental stellar properties, as provided by this work, are likely to be useful in the characterization of the corresponding candidate planetary systems. Furthermore, an important byproduct of the current work is the confirmation that amplitudes of solar-like oscillations are suppressed in stars with increased levels of surface magnetic activity.

  1. Non-enzymatic hydrogen peroxide detection at NiO nanoporous thin film- electrodes prepared by physical vapor deposition at oblique angles

    International Nuclear Information System (INIS)

    Salazar, Pedro; Rico, Victor; González-Elipe, Agustín R.

    2017-01-01

    Highlights: • A non-enzymatic sensor for H 2 O 2 detection based on nickel thin film is reported. • Nanostructured nickel thin films are prepared by physical vapor deposition at oblique angles. • Main analytical parameters were obtained under optimal operation conditions. • Sensors depict an outstanding selectivity and a high stability. • Sensors are successfully used to determine H 2 O 2 in antiseptic solutions. - Abstract: In this work we report a non-enzymatic sensor for hydrogen peroxide (H 2 O 2 ) detection based on nanostructured nickel thin films prepared by physical vapor deposition at oblique angles. Porous thin films deposited on ITO substrates were characterized by X-ray diffraction analysis, scanning electron microcopy (SEMs), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques such as Cyclic Voltammetry (CV) and Constant Potential Amperometry (CPA). The microstructure of the thin films consisted of inclined and separated Ni nanocolumns forming a porous thin layer of about 500 nm thickness. Prior to their use, the films surface was electrochemically modified and the chemical state studied by CV and XPS analysis. These techniques also showed that Ni 2+ /Ni 3+ species were involved in the electrochemical oxidation and detection of H 2 O 2 in alkaline medium. Main analytical parameters such as sensitivity (807 mA M −1 cm −2 ), limit of detection (3.22 μM) and linear range (0.011–2.4 mM) were obtained under optimal operation conditions. Sensors depicted an outstanding selectivity and a high stability and they were successfully used to determine H 2 O 2 concentration in commercial antiseptic solutions.

  2. Detection of bacteria based on the thermomechanical noise of a nanomechanical resonator: origin of the response and detection limits

    International Nuclear Information System (INIS)

    Ramos, D; Tamayo, J; Mertens, J; Calleja, M; Villanueva, L G; Zaballos, A

    2008-01-01

    We have measured the effect of bacteria adsorption on the resonant frequency of microcantilevers as a function of the adsorption position and vibration mode. The resonant frequencies were measured from the Brownian fluctuations of the cantilever tip. We found that the sign and amount of the resonant frequency change is determined by the position and extent of the adsorption on the cantilever with regard to the shape of the vibration mode. To explain these results, a theoretical one-dimensional model is proposed. We obtain analytical expressions for the resonant frequency that accurately fit the data obtained by the finite element method. More importantly, the theory data shows a good agreement with the experiments. Our results indicate that there exist two opposite mechanisms that can produce a significant resonant frequency shift: the stiffness and the mass of the bacterial cells. Based on the thermomechanical noise, we analyse the regions of the cantilever of lowest and highest sensitivity to the attachment of bacteria. The combination of high vibration modes and the confinement of the adsorption to defined regions of the cantilever allows the detection of single bacterial cells by only measuring the Brownian fluctuations. This study can be extended to smaller cantilevers and other biological systems such as proteins and nucleic acids

  3. The determination of levofloxacin by flow injection analysis using UV detection, potentiometry, and conductometry in pharmaceutical preparations.

    Science.gov (United States)

    Altiokka, G; Atkosar, Z; Can, N O

    2002-10-15

    A flow injection analysis (FIA) using UV detection, potentiometry and conductometry for levofloxacin (LVF) are described in this study. The best solvent system was found to consist of 0.2 M acetate buffer at pH 3 having 10% MeOH. A flow rate of 1 ml min(-1) was pumped and active material was detected at 288 nm. The detection limit (LOD) and limit of quantification (LOQ) for FIA were calculated to be 3 x 10(-7) M (S/N = 3) and 1 x 10(-7) M (S/N = 10), respectively. In the analysis of tablets, the RSD values were found to be 0.83, 0.98 and 0.99 for FIA, potentiometric and conductometric methods, respectively. Copyright 2002 Elsevier Science B.V.

  4. Improved detection limits for electrospray ionization on a magnetic sector mass spectrometer by using an array detector.

    Science.gov (United States)

    Cody, R B; Tamura, J; Finch, J W; Musselman, B D

    1994-03-01

    Array detection was compared with point detection for solutions of hen egg-white lysozyme, equine myoglobin, and ubiquitin analyzed by electrospray ionization with a magnetic sector mass spectrometer. The detection limits for samples analyzed by using the array detector system were at least 10 times lower than could be achieved by using a point detector on the same mass spectrometer. The minimum detectable quantity of protein corresponded to a signal-to-background ratio of approximately 2∶1 for a 500 amol/μL solution of hen egg-white lysozyme. However, the ultimate practical sample concentrations appeared to be in the 10-100 fmol/μL range for the analysis of dilute solutions of relatively pure proteins or simple mixtures.

  5. The physics of detecting torsion and placing limits on its effects

    International Nuclear Information System (INIS)

    Stoeger, W.R.

    1985-01-01

    The essential principles of torsion-detection physics are presented and several conceivable types of experiments and observations for actually detecting torsion fields are evaluated reemphasizing also the evident impossibility of successfully searching for its manifestations among cosmological relics. In particular, a polarized body, with net intrinsic (fundamental-particle) spin, is essential for detecting a torsion field. One which possesses only orbital angular momentum-rotation-or an unpolarized intrinsic spin density will not feel torsion. The fundamental problem in searching for such fields is the extremely small basic unit of the coupling or interaction energy between the torsion field and spin, epsilonapprox.(8πG'/c 2 )(h 2 /4). The best way of maximizing the total interaction energy is to increase the spin density of the source σ 5 and, at the same time the ''spin number'' Ssub(D) of the detector. (author)

  6. Limitations to depth resolution in high-energy, heavy-ion elastic recoil detection analysis

    International Nuclear Information System (INIS)

    Elliman, R.G.; Palmer, G.R.; Ophel, T.R.; Timmers, H.

    1998-01-01

    The depth resolution of heavy-ion elastic recoil detection analysis was examined for Al and Co thin films ranging in thickness from 100 to 400 nm. Measurements were performed with 154 MeV Au ions as the incident beam, and recoils were detected using a gas ionisation detector. Energy spectra were extracted for the Al and Co recoils and the depth resolution determined as a function of film thickness from the width of the high- and low- energy edges. These results were compared with theoretical estimates calculated using the computer program DEPTH. (authors)

  7. The Cu-MOF-199/single-walled carbon nanotubes modified electrode for simultaneous determination of hydroquinone and catechol with extended linear ranges and lower detection limits

    International Nuclear Information System (INIS)

    Zhou, Jian; Li, Xi; Yang, Linlin; Yan, Songlin; Wang, Mengmeng; Cheng, Dan; Chen, Qi; Dong, Yulin; Liu, Peng; Cai, Weiquan; Zhang, Chaocan

    2015-01-01

    A novel electrochemical sensor based on Cu-MOF-199 [Cu-MOF-199 = Cu 3 (BTC) 2 (BTC = 1,3,5-benzenetricarboxylicacid)] and SWCNTs (single-walled carbon nanotubes) was fabricated for the simultaneous determination of hydroquinone (HQ) and catechol (CT). The modification procedure was carried out through casting SWCNTs on the bare glassy carbon electrode (GCE) and followed by the electrodeposition of Cu-MOF-199 on the SWCNTs modified electrode. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were performed to characterize the electrochemical performance and surface characteristics of the as-prepared sensor. The composite electrode exhibited an excellent electrocatalytic activity with increased electrochemical signals towards the oxidation of HQ and CT, owing to the synergistic effect of SWCNTs and Cu-MOF-199. Under the optimized condition, the linear response range were from 0.1 to 1453 μmol L −1 (R HQ  = 0.9999) for HQ and 0.1–1150 μmol L −1 (R CT  = 0.9990) for CT. The detection limits for HQ and CT were as low as 0.08 and 0.1 μmol L −1 , respectively. Moreover, the modified electrode presented the good reproducibility and the excellent anti-interference performance. The analytical performance of the developed sensor for the simultaneous detection of HQ and CT had been evaluated in practical samples with satisfying results. - Highlights: • Cu-MOF-199/SWCNTs/GCE was facilely fabricated by the electrodeposition on SWCNTs/GCE. • An electrochemical sensor for detecting HQ and CT was constructed based on this modified electrode. • The proposed electrochemical sensor showed an extended linear range and lower detection limits. • The proposed electrochemical sensor had an excellent stability and reproducibility.

  8. High-Throughput Analysis With 96-Capillary Array Electrophoresis and Integrated Sample Preparation for DNA Sequencing Based on Laser Induced Fluorescence Detection

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Gang [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    The purpose of this research was to improve the fluorescence detection for the multiplexed capillary array electrophoresis, extend its use beyond the genomic analysis, and to develop an integrated micro-sample preparation system for high-throughput DNA sequencing. The authors first demonstrated multiplexed capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) separations in a 96-capillary array system with laser-induced fluorescence detection. Migration times of four kinds of fluoresceins and six polyaromatic hydrocarbons (PAHs) are normalized to one of the capillaries using two internal standards. The relative standard deviations (RSD) after normalization are 0.6-1.4% for the fluoresceins and 0.1-1.5% for the PAHs. Quantitative calibration of the separations based on peak areas is also performed, again with substantial improvement over the raw data. This opens up the possibility of performing massively parallel separations for high-throughput chemical analysis for process monitoring, combinatorial synthesis, and clinical diagnosis. The authors further improved the fluorescence detection by step laser scanning. A computer-controlled galvanometer scanner is adapted for scanning a focused laser beam across a 96-capillary array for laser-induced fluorescence detection. The signal at a single photomultiplier tube is temporally sorted to distinguish among the capillaries. The limit of detection for fluorescein is 3 x 10-11 M (S/N = 3) for 5-mW of total laser power scanned at 4 Hz. The observed cross-talk among capillaries is 0.2%. Advantages include the efficient utilization of light due to the high duty-cycle of step scan, good detection performance due to the reduction of stray light, ruggedness due to the small mass of the galvanometer mirror, low cost due to the simplicity of components, and flexibility due to the independent paths for excitation and emission.

  9. Limited evidence for the use of imaging to detect prostate cancer: A systematic review

    International Nuclear Information System (INIS)

    Blomqvist, L.; Carlsson, S.; Gjertsson, P.; Heintz, E.; Hultcrantz, M.; Mejare, I.; Andrén, O.

    2014-01-01

    Highlights: • In men with clinical suspicion of prostate cancer, ultrasound guided systematic biopsies is the golden standard for diagnosis. • Diagnostic imaging techniques, especially magnetic resonance imaging, is being used in trials to aid detection of prostate cancer. • To date, there is insufficient scientific evidence for the use of imaging techniques to detect prostate cancer. - Abstract: Objective: To assess the diagnostic accuracy of imaging technologies for detecting prostate cancer in patients with elevated PSA-values or suspected findings on clinical examination. Methods: The databases Medline, EMBASE, Cochrane, CRD HTA/DARE/NHS EED and EconLit were searched until June 2013. Pre-determined inclusion criteria were used to select full text articles. Risk of bias in individual studies was rated according to QUADAS or AMSTAR. Abstracts and full text articles were assessed independently by two reviewers. The performance of diagnostic imaging was compared with systematic biopsies (reference standard) and sensitivity and specificity were calculated. Results: The literature search yielded 5141 abstracts, which were reviewed by two independent reviewers. Of these 4852 were excluded since they did not meet the inclusion criteria. 288 articles were reviewed in full text for quality assessment. Six studies, three using MRI and three using transrectal ultrasound were included. All were rated as high risk of bias. Relevant studies on PET/CT were not identified. Conclusion: Despite clinical use, there is insufficient evidence regarding the accuracy of imaging technologies for detecting cancer in patients with suspected prostate cancer using TRUS guided systematic biopsies as reference standard

  10. Limited evidence for the use of imaging to detect prostate cancer: A systematic review

    Energy Technology Data Exchange (ETDEWEB)

    Blomqvist, L., E-mail: lennart.k.blomqvist@ki.se [Department of Diagnostic Radiology, Karolinska University Hospital, Solna (Sweden); Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm (Sweden); Carlsson, S. [Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm (Sweden); Department of Urology, Karolinska University Hospital, Solna (Sweden); Gjertsson, P. [Department of Clinical Physiology, Sahlgrenska University Hospital, Gothenburg (Sweden); Heintz, E.; Hultcrantz, M.; Mejare, I. [The Swedish Council on Health Technology Assessment, Stockholm (Sweden); Andrén, O. [School of Health and Medical Sciences, Örebro University, Örebro (Sweden); Department of Urology, Örebro University Hospital, Örebro (Sweden)

    2014-09-15

    Highlights: • In men with clinical suspicion of prostate cancer, ultrasound guided systematic biopsies is the golden standard for diagnosis. • Diagnostic imaging techniques, especially magnetic resonance imaging, is being used in trials to aid detection of prostate cancer. • To date, there is insufficient scientific evidence for the use of imaging techniques to detect prostate cancer. - Abstract: Objective: To assess the diagnostic accuracy of imaging technologies for detecting prostate cancer in patients with elevated PSA-values or suspected findings on clinical examination. Methods: The databases Medline, EMBASE, Cochrane, CRD HTA/DARE/NHS EED and EconLit were searched until June 2013. Pre-determined inclusion criteria were used to select full text articles. Risk of bias in individual studies was rated according to QUADAS or AMSTAR. Abstracts and full text articles were assessed independently by two reviewers. The performance of diagnostic imaging was compared with systematic biopsies (reference standard) and sensitivity and specificity were calculated. Results: The literature search yielded 5141 abstracts, which were reviewed by two independent reviewers. Of these 4852 were excluded since they did not meet the inclusion criteria. 288 articles were reviewed in full text for quality assessment. Six studies, three using MRI and three using transrectal ultrasound were included. All were rated as high risk of bias. Relevant studies on PET/CT were not identified. Conclusion: Despite clinical use, there is insufficient evidence regarding the accuracy of imaging technologies for detecting cancer in patients with suspected prostate cancer using TRUS guided systematic biopsies as reference standard.

  11. Detecting gravitational waves from precessing binaries of spinning compact objects: Adiabatic limit

    International Nuclear Information System (INIS)

    Buonanno, Alessandra; Chen Yanbei; Vallisneri, Michele

    2003-01-01

    Black-hole (BH) binaries with single-BH masses m=(5-20)M · , moving on quasicircular orbits, are among the most promising sources for first-generation ground-based gravitational-wave (GW) detectors. Until now, the development of data-analysis techniques to detect GWs from these sources has been focused mostly on nonspinning BHs. The data-analysis problem for the spinning case is complicated by the necessity to model the precession-induced modulations of the GW signal, and by the large number of parameters needed to characterize the system, including the initial directions of the spins, and the position and orientation of the binary with respect to the GW detector. In this paper we consider binaries of maximally spinning BHs, and we work in the adiabatic-inspiral regime to build families of modulated detection templates that (i) are functions of very few physical and phenomenological parameters, (ii) model remarkably well the dynamical and precessional effects on the GW signal, with fitting factors on average > or approx. 0.97, (iii) but, however, might require increasing the detection thresholds, offsetting at least partially the gains in the fitting factors. Our detection-template families are quite promising also for the case of neutron-star-black-hole binaries, with fitting factors on average ≅0.93. For these binaries we also suggest (but do not test) a further template family, which would produce essentially exact waveforms written directly in terms of the physical spin parameters

  12. Adaptive Framework for Classification and Novel Class Detection over Evolving Data Streams with Limited Labeled Data.

    Energy Technology Data Exchange (ETDEWEB)

    Haque, Ahsanul [Univ. of Texas, Dallas, TX (United States); Khan, Latifur [Univ. of Texas, Dallas, TX (United States); Baron, Michael [Univ. of Texas, Dallas, TX (United States); Ingram, Joey Burton [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Most approaches to classifying evolving data streams either divide the stream of data into fixed-size chunks or use gradual forgetting to address the problems of infinite length and concept drift. Finding the fixed size of the chunks or choosing a forgetting rate without prior knowledge about time-scale of change is not a trivial task. As a result, these approaches suffer from a trade-off between performance and sensitivity. To address this problem, we present a framework which uses change detection techniques on the classifier performance to determine chunk boundaries dynamically. Though this framework exhibits good performance, it is heavily dependent on the availability of true labels of data instances. However, labeled data instances are scarce in realistic settings and not readily available. Therefore, we present a second framework which is unsupervised in nature, and exploits change detection on classifier confidence values to determine chunk boundaries dynamically. In this way, it avoids the use of labeled data while still addressing the problems of infinite length and concept drift. Moreover, both of our proposed frameworks address the concept evolution problem by detecting outliers having similar values for the attributes. We provide theoretical proof that our change detection method works better than other state-of-the-art approaches in this particular scenario. Results from experiments on various benchmark and synthetic data sets also show the efficiency of our proposed frameworks.

  13. Group-focused morality is associated with limited conflict detection and resolution capacity: Neuroanatomical evidence.

    Science.gov (United States)

    Nash, Kyle; Baumgartner, Thomas; Knoch, Daria

    2017-02-01

    Group-focused moral foundations (GMFs) - moral values that help protect the group's welfare - sharply divide conservatives from liberals and religiously devout from non-believers. However, there is little evidence about what drives this divide. Moral foundations theory and the model of motivated social cognition both associate group-focused moral foundations with differences in conflict detection and resolution capacity, but in opposing directions. Individual differences in conflict detection and resolution implicate specific neuroanatomical differences. Examining neuroanatomy thus affords an objective and non-biased opportunity to contrast these influential theories. Here, we report that increased adherence to group-focused moral foundations was strongly associated (whole-brain corrected) with reduced gray matter volume in key regions of the conflict detection and resolution system (anterior cingulate cortex and lateral prefrontal cortex). Because reduced gray matter is reliably associated with reduced neural and cognitive capacity, these findings support the idea outlined in the model of motivated social cognition that belief in group-focused moral values is associated with reduced conflict detection and resolution capacity. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Evaluation of a single-item screening question to detect limited health literacy in peritoneal dialysis patients.

    Science.gov (United States)

    Jain, Deepika; Sheth, Heena; Bender, Filitsa H; Weisbord, Steven D; Green, Jamie A

    2014-01-01

    Studies have shown that a single-item question might be useful in identifying patients with limited health literacy. However, the utility of the approach has not been studied in patients receiving maintenance peritoneal dialysis (PD). We assessed health literacy in a cohort of 31 PD patients by administering the Rapid Estimate of Adult Literacy in Medicine (REALM) and a single-item health literacy (SHL) screening question "How confident are you filling out medical forms by yourself?" (Extremely, Quite a bit, Somewhat, A little bit, or Not at all). To determine the accuracy of the single-item question for detecting limited health literacy, we performed sensitivity and specificity analyses of the SHL and plotted the area under the receiver operating characteristic (AUROC) curve using the REALM as a reference standard. Using a cut-off of "Somewhat" or less confident, the sensitivity of the SHL for detecting limited health literacy was 80%, and the specificity was 88%. The positive likelihood ratio was 6.9. The SHL had an AUROC of 0.79 (95% confidence interval: 0.52 to 1.00). Our results show that the SHL could be effective in detecting limited health literacy in PD patients.

  15. The limits of application of variable-energy slow positron beams for investigating TiN hard coatings prepared by PVD

    International Nuclear Information System (INIS)

    Marek, T.; Suevegh, K.; Vertes, A.; Szeles, Cs.; Lynn, K.G.

    2000-01-01

    Samples of TiN hard coatings prepared by physical vapour deposition (PVD) were investigated by means of depth-sensitive positron annihilation spectroscopy. The results indicate that the samples are at the limits of the applicability of this method presumably due to the high defect concentration. Though the samples are thoroughly characterized by other independent methods, they might not be sufficient to explain all aspects of positron-solid interactions in these cases. (author)

  16. Preparation of Immuno-magnetic Beads and Their Separation & Detection to Ovary Cancer Cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The organic monomer-molecule with nanometer magnetic powder by means of reforming the surface of nanometer magnetic powder have been synthesized.Magnetic beads in diameter of 2μm or so are obtained by controlling conditions.Ovary cancer cells of ascites are separated and ovary cancer cells of blood are detected by using immuno-magnetic beads linked with ovary cancer cell mono-antibodies.Results show that the specificity is 85%,sensitivity is 87%,accuracy is 84%,cells acquiring purity is 90%,cells activity is 92% and detection sensitivity is 25×10-7.

  17. The value and limitations of contrast-enhanced transrectal ultrasonography for the detection of prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Han-Xue, E-mail: zhaohx861@163.com [Department of Diagnostic Ultrasound, Beijing Tongren Hospital, Capital Medical University, Dong-Jiao-Min-Xiang, Dong Cheng District, Beijing 100730 (China); Xia, Chun-Xia, E-mail: star9901482@163.com [Department of Diagnostic Ultrasound, Beijing Tongren Hospital, Capital Medical University, Dong-Jiao-Min-Xiang, Dong Cheng District, Beijing 100730 (China); Yin, Hong-Xia, E-mail: hongxia_yin79@yahoo.com.cn [Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Dong-Jiao-Min-Xiang, Dong Cheng District, Beijing 100730 (China); Guo, Ning, E-mail: ningguo99@sina.com.cn [Department of Diagnostic Ultrasound, Beijing Tongren Hospital, Capital Medical University, Dong-Jiao-Min-Xiang, Dong Cheng District, Beijing 100730 (China); Zhu, Qiang, E-mail: qzhutrhos@gmail.com [Department of Diagnostic Ultrasound, Beijing Tongren Hospital, Capital Medical University, Dong-Jiao-Min-Xiang, Dong Cheng District, Beijing 100730 (China)

    2013-11-01

    Objectives: To evaluate the role of contrast-enhanced transrectal ultrasonography (CE-TRUS) for detecting prostate carcinoma. Methods: Sixty-five patients with elevated serum prostate-specific antigen (PSA) and/or abnormal digital rectal examination (DRE) were assessed using transrectal ultrasound (TRUS) and CE-TRUS. In all the patients, CE-TRUS was performed with intravenous injection of contrast agent (SonoVue, 2.4 ml) before biopsy. The cancer detection rates of the two techniques were compared. False-positive and false-negative findings related to CE-TRUS were analyzed in comparison to the pathological results of biopsy or radical prostatectomy. The targeted biopsy to abnormal CE-TRUS areas was also compared to systematic biopsy. Results: Prostate cancer was detected in 29 of the 65 patients. CE-TRUS showed rapid focal enhancement or asymmetric vessels of peripheral zones in 28 patients; 23 of them had prostate cancer. CE-TRUS had 79.3% sensitivity, compared to 65.5% of TRUS (P < 0.05). There were five false-positive and six false-negative findings from CE-TRUS. Benign prostate hyperplasia, and acute and chronic prostatitis were important causes related to the false-positive results of CE-TRUS. Prostate cancer originating from the transition zone or peripheral zone with lower PSA levels, small-size foci, and moderately or well-differentiated tumor was missed by CE-TRUS. The cancer detection rate of targeted biopsy (75%, 33/44 cores) was significantly higher than one of systematic biopsy (48.2%, 162/336) in those 28 cases (P < 0.05). In addition, no significant correlation was found between the cancer detection rate with CE-TRUS and serum PSA levels. Conclusion: CE-TRUS may improve the detection rate of prostate cancer through targeted biopsy of contrast-enhanced abnormalities. Our findings indicate that systematic biopsies should not be eliminated on the basis of false-positive and false-negative findings related to CE-TRUS.

  18. Lower limit of detection: definition and elaboration of a proposed position for radiological effluent and environmental measurements

    International Nuclear Information System (INIS)

    Currie, L.A.

    1984-09-01

    A manual is provided to define and illustrate a proposed use of the Lower Limit of Detection (LLD) for Radiological Effluent and Environmental Measurements. The manual contains a review of information regarding LLD practices gained from site visits; a review of the literature and a summary of basic principles underlying the concept of detection in Nuclear and Analytical Chemistry; a detailed presentation of the application of LLD principles to a range of problem categories (simple counting to multinuclide spectroscopy), including derivations, equations, and numerical examples; and a brief examination of related issues such as reference samples, numerical quality control, and instrumental limitations. An appendix contains a summary of notation and terminology, a bibliography, and worked-out examples. 100 references, 10 figures, 7 tables

  19. Detection limits in the chromatographic element trace analysis - quantitative TLC, HPLC and GC with the example of beryllium acetylacetonate

    International Nuclear Information System (INIS)

    Schwedt, G.

    1981-01-01

    Chromatographic analyses of beryllium acetylacetonate are carried out in synthetic solutions within the nano- and picogram range of beryllium. For thin-layer chromatography (TLC) normal and silanized silica gel is used, for high-performance liquid chromatography (HPLC) silica gel of 7 μm particles, for gas chromatography (GC) silicone SE-30 as stationary phase. Visual evaluation and remission measurements in TLC, UV-254 nm absorption measurements in HPLC and measurements with a FID in GC are employed for the determination of the calibration curves. A calibration curve through the origin and a detection limit of 150 pg Be determinable form are received by HPLC only. For trace analyses by GC a new definition of a detection limit for the evaluation of substance peaks on a solvent tailing is suggested. (orig.) [de

  20. One-step electrochemical deposition of a graphene-ZrO2 nanocomposite: Preparation, characterization and application for detection of organophosphorus agents

    Energy Technology Data Exchange (ETDEWEB)

    Du, Dan; Liu, Juan; Zhang, Xiao-Yan; Cui, Xiao-Li; Lin, Yuehe

    2011-04-27

    This paper described the preparation, characterization, and electrochemical properties of a graphene-ZrO2 nanocomposite (GZN) and its application for both the enrichment and detection of methyl parathion (MP). GZN was fabricated using electrochemical deposition and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), which showed the successful formation of nanocomposites. Due to the strong affinity to the phosphoric group and the fast electron-transfer kinetics of GZN, both the extraction and electrochemical detection of organophosphorus (OP) agents at the same GZN modified electrochemical sensor was possible. The combination of solid-phase extraction and stripping voltammetric analysis allowed fast, sensitive, and selective determination of MP in garlic samples. The stripping response was highly linear over the MP concentrations ranging from 0.5 ng mL-1 to 100 ng mL-1, with a detection limit of 0.1 ng mL-1. This new nanocomposite-based electrochemical sensor provides an opportunity to develop a field-deployable, sensitive, and quantitative method for monitoring exposure to OPs.

  1. Preparation, characterization and evaluation of water-soluble L-cysteine-capped-CdS nanoparticles as fluorescence probe for detection of Hg(II) in aqueous solution

    International Nuclear Information System (INIS)

    Cai Zhaoxia; Yang Hong; Zhang Yi; Yan Xiuping

    2006-01-01

    Water-soluble L-cysteine-capped-CdS nanoparticles were prepared in aqueous solution at room temperature through a straightforward one-pot process by using safe and low-cost inorganic salts as precursors, and characterized by transmission electron microscopy, X-ray diffraction spectrometry, Fourier transform infrared spectrometry, spectrofluorometry and ultraviolet-visible spectrometry. The prepared L-cysteine-capped-CdS nanoparticles were evaluated as fluorescence probe for Hg(II) detection. The fluorescence quenching of the L-cysteine-capped-CdS nanoparticles depended on the concentration and pH of Hg(II) solution. Maximum fluorescence quenching was observed at pH 7.4 with the excitation and emission wavelengths of 360 nm and 495 nm, respectively. Quenching of its fluorescence due to Hg(II) at the 20 nmol l -1 level was unaffected by the presence of 5 x 10 6 -fold excesses of Na(I) and K(I), 5 x 10 5 -fold excesses of Mg(II), 5 x 10 4 -fold excesses of Ca(II), 500-fold excesses of Al(III), 91-fold excesses of Mn(II), 23.5-fold excesses of Pb(II), 25-fold excesses of Fe(III), 25-fold excesses of Ag(I), 8.5-fold excesses of Ni(II) and 5-fold excesses of Cu(II). Under optimal conditions, the quenched fluorescence intensity increased linearly with the concentration of Hg(II) ranging from 16 nmol l -1 to 112 nmol l -1 . The limit of detection for Hg(II) was 2.4 nmol l -1 . The developed method was applied to the detection of trace Hg(II) in aqueous solutions

  2. Sensitivities and detection limits of X-ray fluorescence analysis with a 10 mCi241Am source

    International Nuclear Information System (INIS)

    Wundt, K.; Janghorbani, M.; Starke, K.

    1976-01-01

    Seven trace elements ranging from chromium to barium were preconcentrated on Amberlite IR-120 cation exchange paper and determined in an energy dispersive X-ray fluorescence system using a 10 mCi 241 Am source. Sensitivities were experimentally determined and checked with theoretically calculated values. The detection limits are compared with elemental levels present in typical surface waters and those allowed in drinking water. Appropriate conclusions as to feasibility of such a system for environmental monitoring are drawn. (orig.) [de

  3. Improved sensitivity and limit-of-detection of lateral flow devices using spatial constrictions of the flow-path.

    Science.gov (United States)

    Katis, Ioannis N; He, Peijun J W; Eason, Robert W; Sones, Collin L

    2018-05-03

    We report on the use of a laser-direct write (LDW) technique that allows the fabrication of lateral flow devices with enhanced sensitivity and limit of detection. This manufacturing technique comprises the dispensing of a liquid photopolymer at specific regions of a nitrocellulose membrane and its subsequent photopolymerisation to create impermeable walls inside the volume of the membrane. These polymerised structures are intentionally designed to create fluidic channels which are constricted over a specific length that spans the test zone within which the sample interacts with pre-deposited reagents. Experiments were conducted to show how these constrictions alter the fluid flow rate and the test zone area within the constricted channel geometries. The slower flow rate and smaller test zone area result in the increased sensitivity and lowered limit of detection for these devices. We have quantified these via the improved performance of a C-Reactive Protein (CRP) sandwich assay on our lateral flow devices with constricted flow paths which demonstrate an improvement in its sensitivity by 62x and in its limit of detection by 30x when compared to a standard lateral flow CRP device. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

  4. Detection Limits for Spectro-fluorometry: A Case Study in the Region of Finstersee, Canton Zug, Northern Switzerland

    Science.gov (United States)

    Otz, M. H.; Otz, H. K.; Keller, P.

    2002-05-01

    Synthetic fluorescent dyes, applied below the visual detection limit (< 0.1 mg/L), have been used as tracers of ground water flow paths since the beginning of the 1950s. Since 1965, we have used spectro-fluorometers with photomultipliers to measure low concentrations of fluorescent dyes in ground water in Switzerland. In collaboration with the Engineering Geology Department of the ETH, we have separated uranine at 0.1 ng/L and Na-naphtionate at 1 ng/L from background fluorescence of spring water in the Finstersee region. These values are 10-100 times lower than postulated detection limits in the literature. The use of low dye concentrations prevents a study region from being contaminated by increased background levels due to remnant dye within the aquifer, thereby leaving the region available for future dye tracing studies. Lower detection limits also can solve particular hydraulic problems where conventional methods fail and enhance the possibility for using artificial dyes in environmentally sensitive aquifer settings.

  5. Generalized linear mixed model for binary outcomes when covariates are subject to measurement errors and detection limits.

    Science.gov (United States)

    Xie, Xianhong; Xue, Xiaonan; Strickler, Howard D

    2018-01-15

    Longitudinal measurement of biomarkers is important in determining risk factors for binary endpoints such as infection or disease. However, biomarkers are subject to measurement error, and some are also subject to left-censoring due to a lower limit of detection. Statistical methods to address these issues are few. We herein propose a generalized linear mixed model and estimate the model parameters using the Monte Carlo Newton-Raphson (MCNR) method. Inferences regarding the parameters are made by applying Louis's method and the delta method. Simulation studies were conducted to compare the proposed MCNR method with existing methods including the maximum likelihood (ML) method and the ad hoc approach of replacing the left-censored values with half of the detection limit (HDL). The results showed that the performance of the MCNR method is superior to ML and HDL with respect to the empirical standard error, as well as the coverage probability for the 95% confidence interval. The HDL method uses an incorrect imputation method, and the computation is constrained by the number of quadrature points; while the ML method also suffers from the constrain for the number of quadrature points, the MCNR method does not have this limitation and approximates the likelihood function better than the other methods. The improvement of the MCNR method is further illustrated with real-world data from a longitudinal study of local cervicovaginal HIV viral load and its effects on oncogenic HPV detection in HIV-positive women. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Internal Dosimetry Monitoring- Detection Limits for a Selected Set of Radionuclides and Their Translation Into Committed Effective Dose

    International Nuclear Information System (INIS)

    Brandl, A.; Hrnecek, E.; Steger, F.

    2004-01-01

    To harmonize the practice of internal dosimetry monitoring across the country, the Austrian Standards Institute is currently drafting a new set of standards which are concerned with occupational incorporation monitoring of individuals handling non-sealed radioactive material. This set of standards is expected to consist of three parts discussing the general necessity and frequency, the requirements for monitoring institutions, and the determination and rigorous calculation of committed effective dose after incorporation of radioactive material, respectively. Considerations of the requirements for routine monitoring laboratories have led to an evaluation of the detection limits for routine monitoring equipment. For a selected set of radionuclides, these detection limits are investigated in detail. The main emphasis is placed on the decay chains of naturally occurring radionuclides showing some significant potential for being out of equilibrium due to chemical processes in certain mining industries. The radionuclides considered in this paper are 226Ra, 228Ra, 228Th, 232Th, 234U, 235U, and 238U. Given the routine monitoring intervals of the Austrian Standard, these detection limits are translated into information on committed effective dose. This paper investigates whether routine monitoring equipment is sufficient to ensure compliance with EC directive 96/29/Euratom for this selected set of radionuclides. (Author) 9 refs

  7. Detection limits by EPR spectroscopy of cumulated doses ionizing radiations in molluscs shells

    International Nuclear Information System (INIS)

    Ostrowski, K.; Burlinska, G.; Dziedzic-Goclawska, A.; Stachowicz, W.; Michalik, J.; Sadlo, J.

    1997-01-01

    The exposure of waters to ionizing radiation from radionuclides stored in concrete containers or freed in nuclear accidents or underwater eruption might be difficult to be proved, when currents, rains, exchange of water displace sand soils or rocks in the bottom. Ionizing radiation evokes stable paramagnetic centers in the crystalline lattice of mineral components in bones as well as in exoskeletons of most molluscs, which are detected by the EPR spectroscopy and could be used as an indicator of the exposure to the action of radiation during prolonged period of time. (authors)

  8. Accuracy and detection limits for bioassay measurements in radiation protection. Statistical considerations

    International Nuclear Information System (INIS)

    Brodsky, A.

    1986-04-01

    This report provides statistical concepts and formulas for defining minimum detectable amount (MDA), bias and precision of sample analytical measurements of radioactivity for radiobioassay purposes. The defined statistical quantities and accuracy criteria were developed for use in standard performance criteria for radiobioassay, but are also useful in intralaboratory quality assurance programs. This report also includes a literature review and analysis of accuracy needs and accuracy recommendations of national and international scientific organizations for radiation or radioactivity measurements used for radiation protection purposes. Computer programs are also included for calculating the probabilities of passing or failing multiple analytical tests for different acceptable ranges of bias and precision

  9. Preparation of metal nanoband microelectrode on poly(dimethylsiloxane) for chip-based amperometric detection

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shaopeng; Wu Jian; Yu Xiaodong [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Xu Jingjuan, E-mail: xujj@nju.edu.cn [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Chen Hongyuan [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education of China, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2010-04-30

    We proposed herein a novel approach for fabricating nanoband microelectrodes for electrochemical detection on an electrophoresis microchip. The metal films were first obtained via region-selective electroless deposition of gold or copper films on PDMS substrates by selective region plasma oxidation through shadow masking. Both metal films show uniform surfaces with the thickness at the level of 100 nm. By casting another PDMS layer on the metal films, the cross section of the sandwich structures can be used as nanoband microelectrodes, which can be renewed just by cutting. These nanoband microelectrodes are successfully used as electrochemical detectors in microchip electrophoresis for the detection of amino acids, proteins and neurotransmitter molecules. Moreover, integrating an Au-Cu double-metal detector with a double-channel electrophoresis system, we can easily distinguish electroactive amino acids from that of non-electroactive amino acids.

  10. Calculation of the detection limits for radionuclides identified in gamma-ray spectra based on post-processing peak analysis results.

    Science.gov (United States)

    Korun, M; Vodenik, B; Zorko, B

    2018-03-01

    A new method for calculating the detection limits of gamma-ray spectrometry measurements is presented. The method is applicable for gamma-ray emitters, irrespective of the influences of the peaked background, the origin of the background and the overlap with other peaks. It offers the opportunity for multi-gamma-ray emitters to calculate the common detection limit, corresponding to more peaks. The detection limit is calculated by approximating the dependence of the uncertainty in the indication on its value with a second-order polynomial. In this approach the relation between the input quantities and the detection limit are described by an explicit expression and can be easy investigated. The detection limit is calculated from the data usually provided by the reports of peak-analyzing programs: the peak areas and their uncertainties. As a result, the need to use individual channel contents for calculating the detection limit is bypassed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Detection of small number of Giardia in biological materials prepared from stray dogs.

    Science.gov (United States)

    Esmailikia, Leila; Ebrahimzade, Elahe; Shayan, Parviz; Amininia, Narges

    2017-12-20

    Giardia lamblia is an intestinal protozoa with intermittent and low shedding especially in dogs, and the detection of Giardia is accompanied with problems such as sampling and diagnostic method. The objective of this study was to detection of Giardia in biological materials with low number of parasite using parasitological and molecular methods, and also to determine whether the examined stray dogs harbor known zoonotic genotype of Giardia. For this aim 85 fecal and duodenal samples were studied from which 1 was positive by Trichrome staining of stool, 4 were positive by staining of duodenal samples. The nested PCR analysis with primers derived from 18 SrRNA showed that the specific PCR product could be amplified in 4 stool and 4 duodenal samples. All positive samples in staining analysis were also positive in nested PCR. No amplification could be observed by nested PCR with primers derived from β giardin gene due to the single copy of gene. Interestingly, the extracted DNA from old fixed stained Giardia positive smears could be also amplified with primers derived from 18SrRNA gene. The sequence analysis of nested PCR products showed that they belong to the genotype D. In conclusion, it is to denote that the Trichrome or Giemsa methods were not suitable for the detection of small number of this parasite in stool and the nested PCR with primers derived from 18S rRNA gene can replace the traditional methods successfully. For detection of Giardia in stool, primers derived from β giardin will not be recommended.

  12. Preparation of Gas Sensor Based on Polymer Nanocomposite for Qualitative Detection of Hydrogen Sulfide

    Directory of Open Access Journals (Sweden)

    Elaheh Ghazizadeh

    2016-11-01

    Full Text Available Hydrogen sulfide (H2S, a by-product often produced in petrochemical processes, is well known as a dangerous and highly toxic gas to living organisms. The smell of H2S concentration of higher than 100 ppm can cause severe biological condition. Therefore, the detection of this gas is a crucial issue. In this work, nanocomposite porous films of polyurethane/silver (PU/Ag and poly(vinylchloride/silver (PVC/Ag consisting of 7 wt% nanoparticles were fabricated by phase inversion method and studied its qualitative detection capacity for H2S. The results indicated that after exposure to 50 ppm H2S, black points appeared on the surface of the test films within 10 min. However, the color completely disappeared when the films were left in the air for 20 min. Structural characteristics of the nanocomposites were studied by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, X-ray diffractometry (XRD and thermal gravimetric analysis (TGA to confirm possible interactions which may have formed between the polymers and nanoparticles. According to the results, Ag nanoparticles were well dispersed in PU and PVC matrices giving particle sizes of less than 62 and 76 nm, respectively. The observations revealed that two recommended nanocomposites (PU/Ag and PVC/Ag could be used for detection of hydrogen sulfide at low level concentration. The response of Ag-embedded polymer films toward H2S vapour showed a better detection by PU/Ag compared to PVC/Ag. Therefore, the suggested silver nanoparticle-loaded PU and PVC sensor films are easily portable, simple to use and cost-less compared with other types of hydrogen sulfide sensors.

  13. Single vial preparation of 99mtc ciprofloxacin for the detection of extrapulmonary tuberculosis

    International Nuclear Information System (INIS)

    Prasad, Vikas; Singh, B.; Bhattacharya, Anish; Mittal, B.R.; Nidhi; Singh, A.K.; Aggarwal, A.

    2005-01-01

    Full text: Aim: To ascertain the usefulness of single vial formulation of Tc-99m Ciprofloxacin (Diagnobact) in detecting extrapulmonary tuberculosis. Introductions: Tuberculosis is one of the major health concerns not only in developing countries but also in the developed nations. Imaging with radiolabelled broad-spectrum antibiotic, being more specific for infection, has the advantage over other nuclear medicine techniques. We are using Diagnobact to detect sites of infection. Methods: 12 patients (age-23 ±11 years, M:F-8:4) of tuberculosis, confirmed by culture/PCR underwent Diagnobact scan. Scanning was done at 1 hour, 4 hour and 24 hours after intravenous injection of 15 mCi of Diagnobact. Rising lesion to background ratio was taken as the criteria for labeling a Diagnobact scan to be positive.Results: Of the 12 patients, two had tibial tuberculous osteomyelitis (TBOM), two vertebral TBOM, one elbow TBOM, four hip joint TBOM, two shaft of femur TBOM and one patient had soft tissue tuberculosis of gluteal region. Diagnobact scan was positive in 10 patients while two patients with vertebral TBOM were negative. Conclusion: Diagnobact, like Infecton, is also useful for the detection of extra pulmonary tuberculosis but for vertebral TBOM. However, more patients need to be studied to reach at statistically significant conclusion. (author)

  14. From alchemy to super-actinides. The preparation, physical-chemical properties and the limits of the Periodic Table

    International Nuclear Information System (INIS)

    Kuruc, J.

    2016-01-01

    In this review a brief history of the discovery of the periodic law, discoveries of elements from the epoch of alchemy to the synthesis of actinides and transactinides is described. The preparation of transactinides (elements with Z ≥ 104 to Z = 118) is discussed, using already proposed names of the elements with Z = 113, 115, 117 and 118: nihonium, moscovium, tennessine and oganesson. The Periodic Tables are presented in short form, the long 18-column and 32-column form. The periodic table containing elements of 8"t"h and 9"t"h periods and its possible range is discussed. By extrapolation of decay half-time of the heaviest isotopes of elements from thorium up to oganesson decay half-time of unbihexium (Z = 126) was predicted about 378 seconds. (author

  15. Sample preparation methods for quantitative detection of DNA by molecular assays and marine biosensors.

    Science.gov (United States)

    Cox, Annie M; Goodwin, Kelly D

    2013-08-15

    The need for quantitative molecular methods is growing in environmental, food, and medical fields but is hindered by low and variable DNA extraction and by co-extraction of PCR inhibitors. DNA extracts from Enterococcus faecium, seawater, and seawater spiked with E. faecium and Vibrio parahaemolyticus were tested by qPCR for target recovery and inhibition. Conventional and novel methods were tested, including Synchronous Coefficient of Drag Alteration (SCODA) and lysis and purification systems used on an automated genetic sensor (the Environmental Sample Processor, ESP). Variable qPCR target recovery and inhibition were measured, significantly affecting target quantification. An aggressive lysis method that utilized chemical, enzymatic, and mechanical disruption enhanced target recovery compared to commercial kit protocols. SCODA purification did not show marked improvement over commercial spin columns. Overall, data suggested a general need to improve sample preparation and to accurately assess and account for DNA recovery and inhibition in qPCR applications. Published by Elsevier Ltd.

  16. Ag/α-Fe2O3 hollow microspheres: Preparation and application for hydrogen peroxide detection

    Science.gov (United States)

    Kang, Xinyuan; Wu, Zhiping; Liao, Fang; Zhang, Tingting; Guo, Tingting

    2015-09-01

    In this paper, we demonstrated a simple approach for preparing α-Fe2O3 hollow spheres by mixing ferric nitrate aqueous and glucose in 180 °C. The glucose was found to act as a soft template in the process of α-Fe2O3 hollow spheres formation. Ag/α-Fe2O3 hollow nanocomposite was obtained under UV irradiation without additional reducing agents or initiators. Synthesized Ag/α-Fe2O3 hollow composites exhibited remarkable catalytic performance toward H2O2 reduction. The electrocatalytic activity mechanism of Ag/α-Fe2O3/GCE were discussed toward the reduction of H2O2 in this paper.

  17. Sample preparation strategies for food and biological samples prior to nanoparticle detection and imaging

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Löschner, Katrin

    2014-01-01

    microscopy (TEM) proved to be necessary for trouble shooting of results obtained from AFFF-LS-ICP-MS. Aqueous and enzymatic extraction strategies were tested for thorough sample preparation aiming at degrading the sample matrix and to liberate the AgNPs from chicken meat into liquid suspension. The resulting...... AFFF-ICP-MS fractograms, which corresponded to the enzymatic digests, showed a major nano-peak (about 80 % recovery of AgNPs spiked to the meat) plus new smaller peaks that eluted close to the void volume of the fractograms. Small, but significant shifts in retention time of AFFF peaks were observed...... for the meat sample extracts and the corresponding neat AgNP suspension, and rendered sizing by way of calibration with AgNPs as sizing standards inaccurate. In order to gain further insight into the sizes of the separated AgNPs, or their possible dissolved state, fractions of the AFFF eluate were collected...

  18. The value and limitation thallium scintigraphy in the detection of coronary artery disease

    International Nuclear Information System (INIS)

    Khan, A.; Rehman, A.; Amin, W.; Khan, Z.A.; Ahmed, S.A.

    1986-01-01

    In this study we randomly selected 45 patients whose coronary angiograms were abnormal i.e. showing triple, double and single vessel disease out of a pool of 80 patients who had undergone stress thallium imaging and coronary angiography during the one year. Majority of these patients were males, their ages ranged between 34-54 years. Resting ECG's were normal in 25 patients, 15 patients had suffered inferior myocardial infraction and 5 had sustained anterior myocardial infraction in the past. Coronary angiography revealed triple vessel disease in 20 patients, double vessel disease in 15, and single vessel coronary artery disease in 10. We analysed their coronary angiograms and compared them with the scintigraphic finding. It is concluded that although thallium scanning has high sensitivity for detection of coronary artery disease in general, it has only moderate sensitivity for detection of stenosis in individual coronary arteries. In this study thallium scan identified 75% of RCA lesions, 66% of LAD lesions and 38% of circumflex lesions. The sensitivity is much higher in single vessel coronary artery disease. (author)

  19. Leak Detection in Waterworks: Comparison Between STFT and FFT with an Overcoming of Limitations

    Directory of Open Access Journals (Sweden)

    Lay-Ekuakille Aimé

    2017-12-01

    Full Text Available Detection of leakages in pipelines is a matter of continuous research because of the basic importance for a waterworks system is finding the point of the pipeline where a leak is located and − in some cases − a nature of the leak. There are specific difficulties in finding leaks by using spectral analysis techniques like FFT (Fast Fourier Transform, STFT (Short Term Fourier Transform, etc. These difficulties arise especially in complicated pipeline configurations, e.g. a zigzag one. This research focuses on the results of a new algorithm based on FFT and comparing them with a developed STFT technique. Even if other techniques are used, they are costly and difficult to be managed. Moreover, a constraint in the leak detection is the pipeline diameter because it influences accuracy of the adopted algorithm. FFT and STFT are not fully adequate for complex configurations dealt with in this paper, since they produce ill-posed problems with an increasing uncertainty. Therefore, an improved Tikhonov technique has been implemented to reinforce FFT and STFT for complex configurations of pipelines. Hence, the proposed algorithm overcomes the aforementioned difficulties due to applying a linear algebraic approach.

  20. Information Limited Oligonucleotide Amplification Assay for Affinity-Based, Parallel Detection Studies.

    Directory of Open Access Journals (Sweden)

    Harish Bokkasam

    Full Text Available Molecular communication systems encounter similar constraints as telecommunications. In either case, channel crosstalk at the receiver end will result in information loss that statistical analysis cannot compensate. This is because in any communication channel there is a physical limit to the amount of information that can be transmitted. We present a novel and simple modified end amplification (MEA technique to generate reduced and defined amounts of specific information in form of short fragments from an oligonucleotide source that also contains unrelated and redundant information. Our method can be a valuable tool to investigate information overflow and channel capacity in biomolecular recognition systems.

  1. Determination of the detection limit and decision threshold for ionizing radiation measurements. Part 2: Fundamentals and application to counting measurements with the influence of sample treatment

    International Nuclear Information System (INIS)

    2000-01-01

    This part of ISO 11929 addresses the field of ionizing radiation measurements in which events (in particular pulses) on samples are counted after treating them (e.g. aliquotation, solution, enrichment, separation). It considers, besides the random character of radioactive decay and of pulse counting, all other influences arising from sample treatment, (e.g. weighing, enrichment, calibration or the instability of the test setup). ISO 11929 consists of the following parts, under the general title Determination of the detection limit and decision threshold for ionizing radiation measurements: Part 1: Fundamentals and application to counting measurements without the influence of sample treatment; Part 2: Fundamentals and application to counting measurements with the influence of sample treatment; Part 3: Fundamentals and application to counting measurements by high resolution gamma spectrometry, without the influence of sample treatment; Part 4: Fundamentals and application to measurements by use of linear scale analogue ratemeters, without the influence of sample treatment. This part of ISO 11929 was prepared in parallel with other International Standards prepared by WG 2 (now WG 17): ISO 11932:1996, Activity measurements of solid materials considered for recycling, re-use or disposal as non radioactive waste, and ISO 11929-1, ISO 11929-3 and ISO 11929-4 and is, consequently, complementary to these documents

  2. Opportunistic mammography screening provides effective detection rates in a limited resource healthcare system.

    Science.gov (United States)

    Teh, Yew-Ching; Tan, Gie-Hooi; Taib, Nur Aishah; Rahmat, Kartini; Westerhout, Caroline Judy; Fadzli, Farhana; See, Mee-Hoong; Jamaris, Suniza; Yip, Cheng-Har

    2015-05-15

    Breast cancer is the leading cause of cancer deaths in women world-wide. In low and middle income countries, where there are no population-based mammographic screening programmes, late presentation is common, and because of inadequate access to optimal treatment, survival rates are poor. Mammographic screening is well-studied in high-income countries in western populations, and because it has been shown to reduce breast cancer mortality, it has become part of the healthcare systems in such countries. However the performance of mammographic screening in a developing country is largely unknown. This study aims to evaluate the performance of mammographic screening in Malaysia, a middle income country, and to compare the stage and surgical treatment of screen-detected and symptomatic breast cancer. A retrospective review of 2510 mammograms performed from Jan to Dec 2010 in a tertiary medical centre is carried out. The three groups identified are the routine (opportunistic) screening group, the targeted (high risk) screening group and the diagnostic group. The performance indicators of each group is calculated, and stage at presentation and treatment between the screening and diagnostic group is analyzed. The cancer detection rate in the opportunistic screening group, targeted screening group, and the symptomatic group is 0.5 %, 1.25 % and 26 % respectively. The proportion of ductal carcinoma in situ is 23.1 % in the two screening groups compared to only 2.5 % in the diagnostic group. Among the opportunistic screening group, the cancer detection rate was 0.2 % in women below 50 years old compared to 0.65 % in women 50 years and above. The performance indicators are within international standards. Early-staged breast cancer (Stage 0-2) were 84.6 % in the screening groups compared to 61.1 % in the diagnostic group. From the results, in a setting with resource constraints, targeted screening of high risk individuals will give a higher yield, and if more resources are

  3. System for detecting and limiting electrical ground faults within electrical devices

    International Nuclear Information System (INIS)

    Gaubatz, D.C.

    1990-01-01

    This paper discusses, in a nuclear power plant of a variety wherein a reactor is provided including a reactor vessel retaining a liquid metal coolant, a reactor core and an electromagnetic pump having inductive windings insulatively retained within the electrically conductive wall of an enclosure, the method for controlling electrical ground fault current between a the inductive winding and the walls. It comprises providing an electrically isolated power source by inductive coupling with the plant power supply; rectifying the power source to provide an isolated d.c. power source; providing an inverter powered from the isolated d.c. power source under the control of the plant control system for selectively energizing the inductive windings; providing a fault control conductor electrically connected with the pump enclosure wall and extending as an electrical return for ground fault current to the inverter; and providing an electrical resistance between the conductor and the isolated inverter having an impedance selected to limit the fault current below a predetermined value limiting arc damage at any the electrical ground fault location

  4. Decision Threshold and Detection Limit in Spectrometric Measurements. Part 1: Application to Gamma Spectrometry

    International Nuclear Information System (INIS)

    Perez, C.; Gasco, C.; Lopez, M. A.

    2010-01-01

    This report summarised the author's lecture of the advanced gamma spectrometry course organised by CIEMAT. The characteristic limits determination in gamma spectrometry generally is obtained through the programming that the trade marks offers to the client with the objective of the automatic calculation of the activity concentrations existing in a sample. In this report, the examples shown in the ISO 11929 standard are compared to the programming realised by Genie 2k for determining characteristic limits. The main difference of both is located in the uncertainty calculations due to the efficiency calibration that is considered by ISO and not by Genie 2K. Through implementation in the software developed by trade marks will be possible to introduce this uncertainty and to assimilate to the calculation done by ISO 11929. In the second part of this report will be analyzed the more complicated samples of this application as counting in a whole body counter (following ISO-28218 about Performance Criteria for radio bioassay), multiplet, overlapping, addition of several peaks for obtaining the activity concentration, etc. (Author) 19 refs.

  5. Sputum-Based Molecular Biomarkers for the Early Detection of Lung Cancer: Limitations and Promise

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Connie E. [Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine. 462 First Avenue, NBV 7N24, New York, NY 10016 (United States); Tchou-Wong, Kam-Meng; Rom, William N., E-mail: william.rom@nyumc.org [Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine. 462 First Avenue, NBV 7N24, New York, NY 10016 (United States); Department of Environmental Medicine, New York University School of Medicine, 57 Old Forge Road, Tuxedo, NY 10987 (United States)

    2011-07-19

    Lung cancer is the leading cause of cancer deaths, with an overall survival of 15% at five years. Biomarkers that can sensitively and specifically detect lung cancer at early stage are crucial for improving this poor survival rate. Sputum has been the target for the discovery of non-invasive biomarkers for lung cancer because it contains airway epithelial cells, and molecular alterations identified in sputum are most likely to reflect tumor-associated changes or field cancerization caused by smoking in the lung. Sputum-based molecular biomarkers include morphology, allelic imbalance, promoter hypermethylation, gene mutations and, recently, differential miRNA expression. To improve the sensitivity and reproducibility of sputum-based biomarkers, we recommend standardization of processing protocols, bronchial epithelial cell enrichment, and identification of field cancerization biomarkers.

  6. On-state voltage drop based power limit detection of IGBT inverters

    DEFF Research Database (Denmark)

    Trintis, Ionut; Ghimire, Pramod; Munk-Nielsen, Stig

    2015-01-01

    Power density is a key performance factor in order to reduce the cost and size of a power converter. Because of the unknown junction temperature, today’s design margins are relatively high to ensure safe and a reliable operation. In this paper, the on-state voltage drop is measured online for all...... insulated gate bipolar transistors (IGBTs) in the inverter, using advanced gate driver. The die temperature is estimated and monitored on each device during power converter operation. Based on the monitored temperature in real time, the maximum power capability is detected. The output power is increased...... until a safe operating temperature of power modules. This enable a power density is increased by 11.16 kW/litre to 19.13 kW/litre in a low voltage power stack which is typically used in wind power converters. Experiment results are shown for safe operation of converter at around 1.2 MW, which is built...

  7. The Impact of an ECV Service is Limited by Antenatal Breech Detection: A Retrospective Cohort Study.

    Science.gov (United States)

    Hemelaar, Joris; Lim, Lee N; Impey, Lawrence W

    2015-06-01

    External cephalic version (ECV) reduces the chance of breech presentation at term birth and lowers the chance of a cesarean delivery. ECV services are now in place in many units in the United Kingdom but their effectiveness is unknown. The aim of this study was to investigate the reasons for breech presentation at term birth. We performed a retrospective cohort study of 394 consecutive babies who were in breech presentation at term birth in a large United Kingdom maternity unit that offers ECV. The cohort was analyzed over two time periods 10 years apart: 1998-1999 and 2008-2009. Only 33.8 percent of women had undergone a (failed) ECV attempt. This low proportion was mainly because breech presentation was not diagnosed antenatally (27.9%). Other contributing factors were: ECV not offered by clinicians (12.2%), ECV declined by women (14%), and contraindications to ECV (10.7%). Over the 10-year period, the proportion of breech presentations that were not diagnosed antenatally increased from 23.2 to 32.5 percent (p = 0.04), which constituted 52.8 percent of women who had not undergone an ECV attempt in 2008-2009. Failure of clinicians to offer ECV reduced from 21.6 to 3.0 percent (p = 0.0001) and the proportion of women declining ECV decreased from 19.1 to 9.0 percent (p = 0.005). Overall, ECV attempts increased from 28.9 to 38.5 percent (p = 0.05). Although ECV counseling, referral, and attempt rates have increased, failure to detect breech presentation antenatally is the principal barrier to successful ECV. Improved breech detection would have a greater impact than methods to increase ECV success rates. © 2015 Wiley Periodicals, Inc.

  8. Beta-trace protein in ascites and pleural effusions: limits of CSF leakage detection.

    Science.gov (United States)

    Dietzel, Joanna; Krebs, Alexander; Böttcher, Dominique; Sieb, Manuela; Glocker, Michael O; Lüdemann, Jan; Roser, Markus; Dressel, Alexander

    2012-06-10

    Rhino- and/or otoliquorrhea can be diagnosed by detecting beta-trace protein (β-TP) in nasal or ear secretions, as β-TP is found in high concentrations in cerebrospinal fluid (CSF) but not in serum. CSF fistulae following trauma or surgery can also occur at other anatomical sites, resulting in CSF leakage into the thoracic and abdominal cavities. By analogy, determination of ß-TP has also been used to diagnose CSF admixture in pleural effusions and ascites. However, no systematic study has yet evaluated the concentrations of β-TP in such fluids in the absence of CSF. To determine the validity of β-TP determination as a marker for the presence of CSF, we investigated β-TP concentrations in pleural effusions and ascites without CSF admixture. Patients from whom samples of ascites or pleural effusion and a paired plasma sample were available were investigated. One hundred sixty-four patients were prospectively recruited. ß-TP concentrations were determined by nephelometry. Mass spectrometric proteome analysis confirmed the presence of ß-TP in the samples. Median β-TP concentrations detected in ascites and pleural effusions (range, 0.014-26.5 mg/L, median 2.29 mg/L) exceeded the corresponding plasma concentrations 2.6-fold. According to cutoffs published to diagnose rhino- and otoliquorrhea, between 6.1% and 95.7% of the specimens would have been erroneously rated CSF-positive. Protein analysis confirmed the presence of β-TP in pleural effusion and ascites. Ascites and pleural effusion contain high concentrations of β-TP that exceed the levels in corresponding plasma. Therefore, β-TP is not a specific marker for the presence of CSF in these fluids.

  9. Analysis of boron utilization in sample preparation for microorganisms detection by neutron radiography technique

    International Nuclear Information System (INIS)

    Wacha, Reinaldo; Crispim, Verginia R.

    2000-01-01

    The neutron radiography technique applied to the microorganisms detection is the study of a new and faster alternative for diagnosis of infectious means. This work presents the parameters and the effects involved in the use of the boron as a conversion agent, that convert neutrons in a particles, capable ones of generating latent tracks in a solid state nuclear tracks detector, CR-39. The collected samples are doped with the boron by the incubation method, propitiating an interaction microorganisms/boron, that will guarantee the identification of the images of those microorganisms, through your morphology. (author)

  10. Solvent-assisted dispersive solid-phase extraction: A sample preparation method for trace detection of diazinon in urine and environmental water samples.

    Science.gov (United States)

    Aladaghlo, Zolfaghar; Fakhari, Alireza; Behbahani, Mohammad

    2016-09-02

    In this research, a sample preparation method termed solvent-assisted dispersive solid-phase extraction (SA-DSPE) was applied. The used sample preparation method was based on the dispersion of the sorbent into the aqueous sample to maximize the interaction surface. In this approach, the dispersion of the sorbent at a very low milligram level was received by inserting a solution of the sorbent and disperser solvent into the aqueous sample. The cloudy solution created from the dispersion of the sorbent in the bulk aqueous sample. After pre-concentration of the diazinon, the cloudy solution was centrifuged and diazinon in the sediment phase dissolved in ethanol and determined by gas chromatography-flame ionization detector. Under the optimized conditions (pH of solution=7.0, Sorbent: benzophenone, 2%, Disperser solvent: ethanol, 500μL, Centrifuge: centrifuged at 4000rpm for 3min), the method detection limit for diazinon was 0.2, 0.3, 0.3 and 0.3μgL(-1) for distilled water, lake water, waste water and urine sample, respectively. Furthermore, the pre-concentration factor was 363.8, 356.1, 360.7 and 353.38 in distilled water, waste water, lake water and urine sample, respectively. SA-DSPE was successfully used for trace monitoring of diazinon in urine, lake and waste water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Detecting deep venous thrombosis with limited flip angle gradient refocused MR imaging

    International Nuclear Information System (INIS)

    Spritzer, C.E.; Sussman, S.K.; Herfkens, R.J.; Blinder, R.A.; Saeed, M.; Vogler, J.A.; Baker, M.E.

    1987-01-01

    This study was undertaken to determine if limited flip angle gradient refocused MR pulse sequences (GRASS) could be used to accurately diagnose deep venous thrombosis (DVT). Sixteen patients (17 extremities) with possible DVT were prospectively evaluated with MR imaging and venography. Typical imaging parameters included a 16-msec echo time, 33-msec repetition time, 30 0 flip angle, and section thickness of 2 nex. MR imaging correctly disclosed the presence (nine cases) or absence (eight cases) of DVT. In one study, GRASS images overestimated the extent of clot due to slow venous blood flow. Subsequently the flip angle was varied to distinguish between venous thrombus and slow flow. When this technique was used, no false-positive studies occurred in the remaining patients. MR gradient refocused imaging appears to be an accurate aid for the diagnosis of DVT

  12. Ag/α-Fe2O3 hollow microspheres: Preparation and application for hydrogen peroxide detection

    International Nuclear Information System (INIS)

    Kang, Xinyuan; Wu, Zhiping; Liao, Fang; Zhang, Tingting; Guo, Tingting

    2015-01-01

    In this paper, we demonstrated a simple approach for preparing α-Fe 2 O 3 hollow spheres by mixing ferric nitrate aqueous and glucose in 180 °C. The glucose was found to act as a soft template in the process of α-Fe 2 O 3 hollow spheres formation. Ag/α-Fe 2 O 3 hollow nanocomposite was obtained under UV irradiation without additional reducing agents or initiators. Synthesized Ag/α-Fe 2 O 3 hollow composites exhibited remarkable catalytic performance toward H 2 O 2 reduction. The electrocatalytic activity mechanism of Ag/α-Fe 2 O 3 /GCE were discussed toward the reduction of H 2 O 2 in this paper. - Graphical abstract: Glucose is carbonized as carbon balls in the 180 °C hydrothermal carbonization process, which plays a role of a soft template. Carbon spherical shell is rich in many hydroxyls, which have good hydrophilicity and surface reactivity. When Fe(NO 3 ) 3 is added to the aqueous solution of Glucose, the hydrophilic -OH will adsorb Fe 3+ to form coordination compound by coordination bond. α-FeOOH is formed on the surface of carbon balls by hydrothermal reaction. After calcination at 500 °C, carbon spheres react with oxygen to form carbon dioxide, which disappears in the air. Meanwhile α-FeOOH is calcined to form α-Fe 2 O 3 hollow spheres.

  13. Sample preparation methods for quantitative detection of DNA by molecular assays and marine biosensors

    International Nuclear Information System (INIS)

    Cox, Annie M.; Goodwin, Kelly D.

    2013-01-01

    Highlights: • DNA extraction methods affected measured qPCR target recovery. • Recovery and variability differed, sometimes by more than an order of magnitude. • SCODA did not offer significant improvement with PCR-inhibited seawater. • Aggressive lysis did appear to improve target recovery. • Reliable and affordable correction methods are needed for quantitative PCR. -- Abstract: The need for quantitative molecular methods is growing in environmental, food, and medical fields but is hindered by low and variable DNA extraction and by co-extraction of PCR inhibitors. DNA extracts from Enterococcus faecium, seawater, and seawater spiked with E. faecium and Vibrio parahaemolyticus were tested by qPCR for target recovery and inhibition. Conventional and novel methods were tested, including Synchronous Coefficient of Drag Alteration (SCODA) and lysis and purification systems used on an automated genetic sensor (the Environmental Sample Processor, ESP). Variable qPCR target recovery and inhibition were measured, significantly affecting target quantification. An aggressive lysis method that utilized chemical, enzymatic, and mechanical disruption enhanced target recovery compared to commercial kit protocols. SCODA purification did not show marked improvement over commercial spin columns. Overall, data suggested a general need to improve sample preparation and to accurately assess and account for DNA recovery and inhibition in qPCR applications

  14. Detection of Salmonella enterica in Meat in Less than 5 Hours by a Low-Cost and Noncomplex Sample Preparation Method

    Science.gov (United States)

    Hoorfar, J.; Hansen, F.; Christensen, J.; Mansdal, S.; Josefsen, M. H.

    2016-01-01

    ABSTRACT Salmonella is recognized as one of the most important foodborne bacteria and has wide health and socioeconomic impacts worldwide. Fresh pork meat is one of the main sources of Salmonella, and efficient and fast methods for detection are therefore necessary. Current methods for Salmonella detection in fresh meat usually include >16 h of culture enrichment, in a few cases meat, consisting of a 3-h enrichment in standard buffered peptone water and a real-time PCR-compatible sample preparation method based on filtration, centrifugation, and enzymatic digestion, followed by fast-cycling real-time PCR detection. The method was validated in an unpaired comparative study against the Nordic Committee on Food Analysis (NMKL) reference culture method 187. Pork meat samples (n = 140) were either artificially contaminated with Salmonella at 0, 1 to 10, or 10 to 100 CFU/25 g of meat or naturally contaminated. Cohen's kappa for the degree of agreement between the rapid method and the reference was 0.64, and the relative accuracy, sensitivity, and specificity for the rapid method were 81.4, 95.1, and 97.9%, respectively. The 50% limit of detections (LOD50s) were 8.8 CFU/25 g for the rapid method and 7.7 CFU/25 g for the reference method. Implementation of this method will enable faster release of Salmonella low-risk meat, providing savings for meat producers, and it will help contribute to improved food safety. IMPORTANCE While the cost of analysis and hands-on time of the presented rapid method were comparable to those of reference culture methods, the fast product release by this method can provide the meat industry with a competitive advantage. Not only will the abattoirs save costs for work hours and cold storage, but consumers and retailers will also benefit from fresher meat with a longer shelf life. Furthermore, the presented sample preparation might be adjusted for application in the detection of other pathogenic bacteria in different sample types. PMID:27986726

  15. Investigation of optical limiting properties of Aluminium nanoparticles prepared by pulsed laser ablation in different carrier media

    International Nuclear Information System (INIS)

    Kuladeep, Rajamudili; Jyothi, L.; Narayana Rao, D.; Prakash, P.; Mayank Shekhar, S.; Durga Prasad, M.

    2013-01-01

    In this communication, we carried out the systematic investigation of nonlinear absorption and scattering properties of Aluminium nanoparticles (Al NPs) in various polar and non-polar solvents. Al NPs were synthesized with pulsed Nd:YAG laser operated at 1064 nm by ablating Al target in polar and non-polar liquid environment like chloroform, chlorobenzene, toluene, benzene, and carbon tetrachloride. Synthesized Al NPs colloids of various solvents differ in appearance and UV-Vis extinction spectra exhibit absorption in the UV region. The characterization of Al NPs performed by Transmission electron microscopy (TEM) studies reveal that NPs are made up of a well crystallized Al inner part (bright zone) embedded with an amorphous metal Al shell (dark region). Growth, aggregation, and precipitation mechanisms which influence the optical properties and stability of NPs are found to be related to the dipole moment of the surrounding liquid environment. The nonlinear absorption and scattering studies are performed by open aperture Z-scan technique with 532 nm under nanosecond pulse excitation. The Z-scan measurements are fitted theoretically to estimate both two-photon absorption (TPA) and nonlinear scattering (NLS) coefficients. In polar solvents like chlorobenzene, chloroform synthesized Al NPs exhibited higher TPA, NLS coefficient values, and lower optical limiting threshold values in comparison with partially polar solvent like toluene and non-polar solvents like benzene and carbontetrachloride. These results indicate the potential use of Al NPs as a versatile optical limiting material

  16. Lower limits of detection in using carbon nanotubes as thermoluminescent dosimeters of beta radiation

    Science.gov (United States)

    Alanazi, Abdulaziz; Jurewicz, Izabela; Alalawi, Amani I.; Alyahyawi, Amjad; Alsubaie, Abdullah; Hinder, Steven; Bañuls-Ciscar, Jorge; Alkhorayef, Mohammed; Bradley, D. A.

    2017-11-01

    World-wide, on-going intensive research is being seen in adaptation of carbon nanotubes (CNTs) for a wide variety of applications, particular interest herein being in the thermoluminescent (TL) properties of CNTs and their sensitivity towards energetic radiations. Using beta radiation delivering dose levels of a few Gy it has been observed in previous study that strain and impurity defects in CNTs give rise to significant TL yields, providing an initial measure of the extent to which electron trapping centres exist in various qualities of CNT, from super-pure to raw. This in turn points to the possibility that there may be considerable advantage in using such media for radiation dosimetry applications, including for in vivo dosimetry. CNTs also have an effective atomic number similar to that of adipose tissue, making them suitable for soft tissue dosimetry. In present investigations various single-wall carbon nanotubes (SWCNT) samples in the form of buckypaper have been irradiated to doses in the range 35-1.3 Gy, use being made of a 90Sr beta source, the response of the CNTs buckypaper with dose showing a trend towards linearity. It is shown for present production methodology for buckypaper samples that the raw SWCNT buckypaper offer the greatest sensitivity, detecting doses down to some few tens of mGy.

  17. Improving the limits of detection of low background alpha emission measurements

    Science.gov (United States)

    McNally, Brendan D.; Coleman, Stuart; Harris, Jack T.; Warburton, William K.

    2018-01-01

    Alpha particle emission - even at extremely low levels - is a significant issue in the search for rare events (e.g., double beta decay, dark matter detection). Traditional measurement techniques require long counting times to measure low sample rates in the presence of much larger instrumental backgrounds. To address this, a commercially available instrument developed by XIA uses pulse shape analysis to discriminate alpha emissions produced by the sample from those produced by other surfaces of the instrument itself. Experience with this system has uncovered two residual sources of background: cosmogenics and radon emanation from internal components. An R&D program is underway to enhance the system and extend the pulse shape analysis technique further, so that these residual sources can be identified and rejected as well. In this paper, we review the theory of operation and pulse shape analysis techniques used in XIA's alpha counter, and briefly explore data suggesting the origin of the residual background terms. We will then present our approach to enhance the system's ability to identify and reject these terms. Finally, we will describe a prototype system that incorporates our concepts and demonstrates their feasibility.

  18. Limitations of the radioimmunoprecipitation polyethylene glycol assay (RIPEGA) for detection of filarial antigens in serum

    International Nuclear Information System (INIS)

    Hamilton, R.G.; Alexander, E.; Adkinson, N.F.

    1984-01-01

    The performance of the radioimmunoprecipitation polyethylene glycol assay (RIPEGA) was examined for quantitation of filarial antigens (Brugia malayi and Dirofilaria immitis) in serum from infected human and animal hosts and non-infected controls. Multiple PEG concentrations were employed to determine the level of non-specific binding (NSB) in non-exposed human sera (NEHS) containing no filarial antigen. The NSB observed when 3 different 125 I-labelled IgG antibodies were added to 26 NEHS varied 3-fold and was correlated significantly with total serum IgM (r = 0.80, P 2 fragment of the 125 I-labelled antibody was used, but the correlation of NSB with total serum IgM remained significant (r = 0.57, P < 0.01). The presence of rheumatoid factor in NEHS sera also significantly increased NSB by an average of 3-fold. These effects eliminated the assay's ability to detect in sera from infected hosts filarial antigen the presence of which could be readily demonstrated by an immunoradiometric assay. The RIPEGA's precision (intra-assay coefficient of variation (CV) = 21% at 35% Bsub(max)) and reproducibility (inter-assay CV = 29% at 35% Bsub(max)) are less satisfactory than many alternative immunoassays. (Auth.)

  19. Rapid and simple preparation of rhodamine 6G loaded HY zeolite for highly selective nitrite detection

    Science.gov (United States)

    Viboonratanasri, Duangkamon; Pabchanda, Suwat; Prompinit, Panida

    2018-05-01

    In this study, a simple, rapid and relatively less toxic method for rhodamine 6G dye adsorption on hydrogen-form Y-type zeolite for highly selective nitrite detection was demonstrated. The adsorption behavior was described by Langmuir isotherm and the adsorption process reached the equilibrium promptly within a minute. The developed test papers characterized by fluorescence technique display high sensing performance with wide working range (0.04-20.0 mg L-1) and high selectivity. The test papers show good reproducibility with relative standard deviation (RSD) of 7% for five replicated determinations of 3 mg L-1 of nitrite. The nitrite concentration determined by using the test paper was in the same range as using ion chromatography within a 95% confidence level. The test papers offer advantages in terms of low cost and practical usage enabling them to be a promising candidate for nitrite sensor in environmental samples, food, and fertilizers.

  20. Limited magnetic resonance imaging of the lumbar spine has high sensitivity for detection of acute fractures, infection, and malignancy

    International Nuclear Information System (INIS)

    Wang, Benjamin; Fintelmann, Florian J.; Kamath, Ravi S.; Kattapuram, Susan V.; Rosenthal, Daniel I.

    2016-01-01

    The objective of this study is to determine how a limited protocol MR examination compares to a full conventional MR examination for the detection of non-degenerative pathology such as acute fracture, infection, and malignancy. A sample of 349 non-contrast MR exams was selected retrospectively containing a 3:1:1:1 distribution of negative/degenerative change only, acute fracture, infection, and malignancy. This resulted in an even distribution of pathology and non-pathology. A limited protocol MR exam was simulated by extracting T1-weighted sagittal and T2-weighted fat-saturated (or STIR) sagittal sequences from each exam and submitting them for blinded review by two experienced musculoskeletal radiologists. The exams were evaluated for the presence or absence of non-degenerative pathology. Interpretation of the limited exam was compared to the original report of the full examination. If either reader disagreed with the original report, the case was submitted for an unblinded adjudication process with the participation of a third musculoskeletal radiologist to establish a consensus diagnosis. There were five false negatives for a sensitivity of 96.9 % for the limited protocol MR exam. Infection in the psoas, paraspinal muscles, and sacroiliac joint, as well as acute fractures in transverse processes and sacrum were missed by one or more readers. No cases of malignancy were missed. Overall diagnostic accuracy was 96.0 % (335/349). MR imaging of the lumbar spine limited to sagittal T1-weighted and sagittal T2 fat-saturated (or STIR) sequences has high sensitivity for the detection of acute fracture, infection, or malignancy compared to a conventional MR examination. (orig.)

  1. Limited magnetic resonance imaging of the lumbar spine has high sensitivity for detection of acute fractures, infection, and malignancy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Benjamin; Fintelmann, Florian J.; Kamath, Ravi S.; Kattapuram, Susan V.; Rosenthal, Daniel I. [Massachusetts General Hospital, Department of Radiology, Boston, MA (United States)

    2016-12-15

    The objective of this study is to determine how a limited protocol MR examination compares to a full conventional MR examination for the detection of non-degenerative pathology such as acute fracture, infection, and malignancy. A sample of 349 non-contrast MR exams was selected retrospectively containing a 3:1:1:1 distribution of negative/degenerative change only, acute fracture, infection, and malignancy. This resulted in an even distribution of pathology and non-pathology. A limited protocol MR exam was simulated by extracting T1-weighted sagittal and T2-weighted fat-saturated (or STIR) sagittal sequences from each exam and submitting them for blinded review by two experienced musculoskeletal radiologists. The exams were evaluated for the presence or absence of non-degenerative pathology. Interpretation of the limited exam was compared to the original report of the full examination. If either reader disagreed with the original report, the case was submitted for an unblinded adjudication process with the participation of a third musculoskeletal radiologist to establish a consensus diagnosis. There were five false negatives for a sensitivity of 96.9 % for the limited protocol MR exam. Infection in the psoas, paraspinal muscles, and sacroiliac joint, as well as acute fractures in transverse processes and sacrum were missed by one or more readers. No cases of malignancy were missed. Overall diagnostic accuracy was 96.0 % (335/349). MR imaging of the lumbar spine limited to sagittal T1-weighted and sagittal T2 fat-saturated (or STIR) sequences has high sensitivity for the detection of acute fracture, infection, or malignancy compared to a conventional MR examination. (orig.)

  2. Quantum-limited detection of millimeter waves using superconducting tunnel junctions

    International Nuclear Information System (INIS)

    Mears, C.A.

    1991-09-01

    The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit by studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 ± 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker's theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs

  3. Comparison of TXRF detection limits for low Z elements in different beam geometries at the PTB monochromator beamline for undulator radiation at Bessy II

    International Nuclear Information System (INIS)

    Beckhoff, B.; Ulm, G.; Pepponi, G.; Streli, C.; Wobrauschek, P.; Fabry, L.; Pahlke, S.

    2000-01-01

    A set of initial TXRF experiments were conducted at the PTB plane grating monochromator beamline for undulator radiation at the electron storage ring BESSY II allowing for exciting energies between 0.1 keV and 1.9 keV. Here, the lower limits of detection of TXRF analysis investigated for some low Z elements such as C, N, 0, Al, Mg and Na in two different detection geometries for various excitation modes. Compared to ordinary XRF geometries involving large incident angles, the TXRF variant offers also at low excitation energies drastically reduced background contributions due to the small penetration depth caused by the total reflection of the incident beam at the polished surface of a flat specimen carrier such as a silicon wafer. For the sake of an application-oriented TXRF approach, droplet samples on Si wafer surfaces were prepared by Wacker Siltronic and investigated in the TXRF irradiation chamber of the Atominstitut offering a semiconductor detector with a thin entrance window that was only 300 nm thick. (author)

  4. Limited role of gadolinium to detect active sacroiliitis on MRI in juvenile spondyloarthritis

    Energy Technology Data Exchange (ETDEWEB)

    Herregods, N.; Leus, A.; Verstraete, K.; Jans, L. [Ghent University Hospital, Department of Radiology and Medical Imaging, Ghent (Belgium); Jaremko, J.L. [University of Alberta Hospital, Department of Radiology and Diagnostic Imaging, Edmonton, AB (Canada); Baraliakos, X. [Ruhr-University Bochum, Rheumazentrum Ruhrgebiet, Herne (Germany); Dehoorne, J. [Ghent University Hospital, Department of Pediatric Rheumatology, Ghent (Belgium)

    2015-11-15

    The aim of this study is to determine the added diagnostic value of contrast-enhanced (CE) magnetic resonance imaging (MRI) compared to routine non contrast-enhanced MRI to detect active sacroiliitis in clinically juvenile spondyloarthritis (JSpA). A total of 80 children clinically suspected for sacroiliitis prospectively underwent MRI of the sacroiliac (SI) joints. Axial and coronal T1-weighted (T1), Short-tau inversion recovery (STIR) and fat-saturated T1-weighted gadolinium-DTPA (Gd) contrast-enhanced (T1/Gd) sequences were obtained. The presence of bone marrow edema (BME), capsulitis, enthesitis, high intra-articular STIR signal, synovial enhancement and a global diagnostic impression of the MRI for diagnosis of sacroiliitis was recorded. STIR and T1/Gd sequences had 100 % agreement for depiction of BME, capsulitis and enthesitis. High intra-articular STIR signal was seen in 18/80 (22.5 %) patients, 15 (83 %) of whom also showed synovial enhancement in the T1/Gd sequence. Sensitivity (SN) and specificity (SP) for a clinical diagnosis of JSpA were similar for high STIR signal (SN = 33 %, SP = 85 %) and T1/Gd synovial enhancement (SN = 36 %, SP = 92 %). Positive likelihood ratio (LR+) for JSpA was twice as high for synovial enhancement than high STIR signal (4.5 compared to 2.2). Global diagnostic impression was similar (STIR: SN = 55 %, SP = 87 %, LR + =4.2; T1/Gd: SN = 55 %, SP = 92 %, LR + = 6.9). MRI without contrast administration is sufficient to identify bone marrow edema, capsulitis and retroarticular enthesitis as features of active sacroiliitis in juvenile spondyloarthritis. In selected cases when high STIR signal in the joint is the only finding, gadolinium-enhanced images may help to confirm the presence of synovitis. (orig.)

  5. Pushing the limits: detecting H2 emission from faint bipolar planetary nebulae in the IPHAS sample

    Science.gov (United States)

    Ramos-Larios, G.; Guerrero, M. A.; Sabin, L.; Santamaría, E.

    2017-09-01

    We have obtained deep narrowband images in the near-infrared H2 λ2.122 μm emission line for a sample of 15 faint Isaac Newton Telescope Photometric H α Survey (IPHAS) bipolar planetary nebulae (PNe) to search for molecular material. H2 emission is found in most of them (14 out of 15), mostly associated with rings at their equatorial regions and with their bipolar lobes. These detections add to the high occurrence of H2 emission among bipolar PNe reported in previous works, resulting from the large reservoir of molecular material in these sources and the suitable excitation conditions for H2 emission. The correlation between detailed bipolar morphology and H2 luminosity is also confirmed: bipolar PNe with broad equatorial rings (R-BPNe) have almost no continuum emission, are H2 brighter and have larger H2/Br γ line ratio than bipolar PNe with pinched equatorial waists (W-BPNe). The origin of this dichotomy is unclear. The larger size and age of R-BPNe are consistent with shock excitation of H2, whereas ultraviolet pumping is most likely the excitation mechanism in the smaller and younger W-BPNe, which would explain their lower H2 luminosity. Although both types of bipolar PNe seem to proceed from the same progenitor population, this does not imply that R-BPNe descend from W-BPNe. Otherwise, we note that some of the H2-weak bipolar PNe harbor post-common envelope binary systems and symbiotic stars. Finally, we suggest that the long-living H2 emission from R-BPNe arises from a discrete distribution of compact knots embedded within the ionized gas at the equatorial region.

  6. [Prokaryotic expression of vp3 gene of Muscovy duck parvovirus, and its antiserum preparation for detection of virus multiplication].

    Science.gov (United States)

    Huang, Yu; Zhu, Yumin; Dong, Shijuan; Yu, Ruisong; Zhang, Yuanshu; Li, Zhen

    2015-01-01

    New epidemic broke out in recent year which was suspected to be caused by variant Muscovy duck parvovirus (MDPV). For this reason, new MDPV detection methods are needed for the new virus strains. In this study, a pair of primers were designed according to the full-length genome of MDPV strain SAAS-SHNH, which were identified in 2012, and were used to amplify the vp3 gene of MDPV by polymerase chain reaction. After being sequenced, the vp3 gene was subcloned into the prokaryotic expression vector PET28a. The recombinant plasmid was transformed into E. coli BL21 and induced with IPTG. SDS-PAGE and Western blotting analysis showed the MDPV vp3 gene was successfully expressed. After being purified by Ni2+ affinity chromatography system, the recombinant protein was used as antigen to immunize rabbits to obtain antiserum. Western blotting analysis showed that the acquired antiserum could react specifically with VP3 protein of J3D6 strain and MDPV vaccine strain. The antiserum could also be used for detection of cultured MDPV from primary duck embryo fibroblasts by immune fluorescence assay (IFA). It could be concluded that the VP3 protein and its antibody prepared in the research could be used for detection of VP3 antiserum and antigen respectively.

  7. Improved detection limit in rapid detection of human enterovirus 71 and coxsackievirus A16 by a novel reverse transcription-isothermal multiple-self-matching-initiated amplification assay.

    Science.gov (United States)

    Ding, Xiong; Nie, Kai; Shi, Lei; Zhang, Yong; Guan, Li; Zhang, Dan; Qi, Shunxiang; Ma, Xuejun

    2014-06-01

    Rapid detection of human enterovirus 71 (EV71) and coxsackievirus A16 (CVA16) is important in the early phase of hand-foot-and-mouth disease (HFMD). In this study, we developed and evaluated a novel reverse transcription-isothermal multiple-self-matching-initiated amplification (RT-IMSA) assay for the rapid detection of EV71 and CVA16 by use of reverse transcriptase, together with a strand displacement DNA polymerase. Real-time RT-IMSA assays using a turbidimeter and visual RT-IMSA assays to detect EV71 and CVA16 were established and completed in 1 h, and the reported corresponding real-time reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assays targeting the same regions of the VP1 gene were adopted as parallel tests. Through testing VP1 RNAs transcribed in vitro, the real-time RT-IMSA assays exhibited better linearity of quantification, with R(2) values of 0.952 (for EV71) and 0.967 (for CVA16), than the real-time RT-LAMP assays, which had R(2) values of 0.803 (for EV71) and 0.904 (for CVA16). Additionally, the detection limits of the real-time RT-IMSA assays (approximately 937 for EV71 and 67 for CVA16 copies/reaction) were higher than those of real-time RT-LAMP assays (approximately 3,266 for EV71 and 430 for CVA16 copies/reaction), and similar results were observed in the visual RT-IMSA assays. The new approaches also possess high specificities for the corresponding targets, with no cross-reactivity observed. In clinical assessment, compared to commercial reverse transcription-quantitative PCR (qRT-PCR) kits, the diagnostic sensitivities of the real-time RT-IMSA assays (96.4% for EV71 and 94.6% for CVA16) were higher than those of the real-time RT-LAMP assays (91.1% for EV71 and 90.8% for CVA16). The visual RT-IMSA assays also exhibited the same results. In conclusion, this proof-of-concept study suggests that the novel RT-IMSA assay is superior to the RT-LAMP assay in terms of detection limit and has the potential to rapidly detect EV71

  8. Cs2AgBiBr6 single-crystal X-ray detectors with a low detection limit

    Science.gov (United States)

    Pan, Weicheng; Wu, Haodi; Luo, Jiajun; Deng, Zhenzhou; Ge, Cong; Chen, Chao; Jiang, Xiaowei; Yin, Wan-Jian; Niu, Guangda; Zhu, Lujun; Yin, Lixiao; Zhou, Ying; Xie, Qingguo; Ke, Xiaoxing; Sui, Manling; Tang, Jiang

    2017-11-01

    Sensitive X-ray detection is crucial for medical diagnosis, industrial inspection and scientific research. The recently described hybrid lead halide perovskites have demonstrated low-cost fabrication and outstanding performance for direct X-ray detection, but they all contain toxic Pb in a soluble form. Here, we report sensitive X-ray detectors using solution-processed double perovskite Cs2AgBiBr6 single crystals. Through thermal annealing and surface treatment, we largely eliminate Ag+/Bi3+ disordering and improve the crystal resistivity, resulting in a detector with a minimum detectable dose rate as low as 59.7 nGyair s-1, comparable to the latest record of 0.036 μGyair s-1 using CH3NH3PbBr3 single crystals. Suppressed ion migration in Cs2AgBiBr6 permits relatively large external bias, guaranteeing efficient charge collection without a substantial increase in noise current and thus enabling the low detection limit.

  9. Detection limits of absorbed dose of ionizing radiation in molluscan shells as determined by e.p.r. spectroscopy

    International Nuclear Information System (INIS)

    Stachowicz, W.; Michalik, J.; Burlinska, G.; Sadlo, J.; Dziedzic-Goclawska, A.; Ostrowski, K.

    1995-01-01

    The exposure of waters to ionizing radiation from radionuclides imprisoned in dumped nuclear waste containers, freed in nuclear submarine accidents or released in underwater magma eruptions are difficult to be evaluated by conventional radiometric methods. Ionizing radiation evokes stable paramagnetic centers in crystalline lattice of mineral components in bone skeletons of mammals and fishes as well as in exoskeletons of mollusca. They give rise in e.p.r. to specific, extremely stable signals which are proposed to be applied as indicators of radiation exposure levels. In the present study the e.p.r. detection limits of the dose of ionizing radiation absorbed in shells of fresh water and marine mollusca (selected species) have been estimated. It has been found that with fresh water mollusca the dose of 1-2 Gy can be detected, while the sea water mollusca by one order of magnitude lower, i.e. about 0.1 Gy. (author)

  10. Protein biomarkers on tissue as imaged via MALDI mass spectrometry: A systematic approach to study the limits of detection.

    Science.gov (United States)

    van de Ven, Stephanie M W Y; Bemis, Kyle D; Lau, Kenneth; Adusumilli, Ravali; Kota, Uma; Stolowitz, Mark; Vitek, Olga; Mallick, Parag; Gambhir, Sanjiv S

    2016-06-01

    MALDI mass spectrometry imaging (MSI) is emerging as a tool for protein and peptide imaging across tissue sections. Despite extensive study, there does not yet exist a baseline study evaluating the potential capabilities for this technique to detect diverse proteins in tissue sections. In this study, we developed a systematic approach for characterizing MALDI-MSI workflows in terms of limits of detection, coefficients of variation, spatial resolution, and the identification of endogenous tissue proteins. Our goal was to quantify these figures of merit for a number of different proteins and peptides, in order to gain more insight in the feasibility of protein biomarker discovery efforts using this technique. Control proteins and peptides were deposited in serial dilutions on thinly sectioned mouse xenograft tissue. Using our experimental setup, coefficients of variation were biomarkers and a new benchmarking strategy that can be used for comparing diverse MALDI-MSI workflows. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Detection Limit of Smectite by Chemin IV Laboratory Instrument: Preliminary Implications for Chemin on the Mars Science Laboratory Mission

    Science.gov (United States)

    Archilles, Cherie; Ming, D. W.; Morris, R. V.; Blake, D. F.

    2011-01-01

    The CheMin instrument on the Mars Science Laboratory (MSL) is an miniature X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument capable of detecting the mineralogical and elemental compositions of rocks, outcrops and soils on the surface of Mars. CheMin uses a microfocus-source Co X-ray tube, a transmission sample cell, and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D XRD patterns and energy-dispersive X-ray histograms from powdered samples. CRISM and OMEGA have identified the presence of phyllosilicates at several locations on Mars including the four candidate MSL landing sites. The objective of this study was to conduct preliminary studies to determine the CheMin detection limit of smectite in a smectite/olivine mixed mineral system.

  12. Scheme for efficient extraction of low-frequency signal beyond the quantum limit by frequency-shift detection.

    Science.gov (United States)

    Yang, R G; Zhang, J; Zhai, Z H; Zhai, S Q; Liu, K; Gao, J R

    2015-08-10

    Low-frequency (Hz~kHz) squeezing is very important in many schemes of quantum precision measurement. But it is more difficult than that at megahertz-frequency because of the introduction of laser low-frequency technical noise. In this paper, we propose a scheme to obtain a low-frequency signal beyond the quantum limit from the frequency comb in a non-degenerate frequency and degenerate polarization optical parametric amplifier (NOPA) operating below threshold with type I phase matching by frequency-shift detection. Low-frequency squeezing immune to laser technical noise is obtained by a detection system with a local beam of two-frequency intense laser. Furthermore, the low-frequency squeezing can be used for phase measurement in Mach-Zehnder interferometer, and the signal-to-noise ratio (SNR) can be enhanced greatly.

  13. Effect of sample matrix composition on INAA sample weights, measurement precisions, limits of detection, and optimum conditions

    International Nuclear Information System (INIS)

    Guinn, V.P.; Nakazawa, L.; Leslie, J.

    1984-01-01

    The instrumental neutron activation analysis (INAA) Advance Prediction Computer Program (APCP) is extremely useful in guiding one to optimum subsequent experimental analyses of samples of all types of matrices. By taking into account the contributions to the cumulative Compton-continuum levels from all significant induced gamma-emitting radionuclides, it provides good INAA advance estimates of detectable photopeaks, measurement precisions, concentration lower limits of detection (LOD's) and optimum irradiation/decay/counting conditions - as well as of the very important maximum allowable sample size for each set of conditions calculated. The usefulness and importance of the four output parameters cited in the title are discussed using the INAA APCP outputs for NBS SRM-1632 Coal as the example

  14. Experimental study to optimize time resolution and detection limit of online 222Rn-in-water measurements

    International Nuclear Information System (INIS)

    Just, G.; Freyer, K.; Treutler, H.C.; Philipsborn, H. von

    2001-01-01

    The possibility to detect short-term variations of the activity concentration of 222 Rn in water by online monitoring with temporal resolutions of a few minutes and a lower limit of detection of about 1 Bq/l enhances the applicability of such measurements. New applications would be possible in the field of hydro-geology in which Rn is used as tracer gas, the monitoring of pumping procedures, for the study of exchange processes during groundwater sampling and for various applications with geophysical effects. A suitable, simple method is the measuring principle proposed by Surbeck (Fribourg) some years ago which is based on the separation of air and water by a diffusion membrane. Process parameters enhancing the time resolution of the method as well as the efficiency of different radon detectors have been studied. (orig.) [de

  15. Determining the 95% limit of detection for waterborne pathogen analyses from primary concentration to qPCR

    Science.gov (United States)

    Stokdyk, Joel P.; Firnstahl, Aaron; Spencer, Susan K.; Burch, Tucker R; Borchardt, Mark A.

    2016-01-01

    The limit of detection (LOD) for qPCR-based analyses is not consistently defined or determined in studies on waterborne pathogens. Moreover, the LODs reported often reflect the qPCR assay alone rather than the entire sample process. Our objective was to develop an approach to determine the 95% LOD (lowest concentration at which 95% of positive samples are detected) for the entire process of waterborne pathogen detection. We began by spiking the lowest concentration that was consistently positive at the qPCR step (based on its standard curve) into each procedural step working backwards (i.e., extraction, secondary concentration, primary concentration), which established a concentration that was detectable following losses of the pathogen from processing. Using the fraction of positive replicates (n = 10) at this concentration, we selected and analyzed a second, and then third, concentration. If the fraction of positive replicates equaled 1 or 0 for two concentrations, we selected another. We calculated the LOD using probit analysis. To demonstrate our approach we determined the 95% LOD for Salmonella enterica serovar Typhimurium, adenovirus 41, and vaccine-derived poliovirus Sabin 3, which were 11, 12, and 6 genomic copies (gc) per reaction (rxn), respectively (equivalent to 1.3, 1.5, and 4.0 gc L−1 assuming the 1500 L tap-water sample volume prescribed in EPA Method 1615). This approach limited the number of analyses required and was amenable to testing multiple genetic targets simultaneously (i.e., spiking a single sample with multiple microorganisms). An LOD determined this way can facilitate study design, guide the number of required technical replicates, aid method evaluation, and inform data interpretation.

  16. Resistance of lichens to simulated galactic cosmic radiation: limits of survival capacity and biosignature detection

    Science.gov (United States)

    de la Torre Noetzel, Rosa; Miller, Ana Z.; Cubero, Beatriz; Raguse, Marina; Meessen, Joachim

    2016-04-01

    Space constitutes an extremely harmful environment for survival of terrestrial organisms. Amongst extremophiles on Earth, lichens are one of the most resistant organisms to harsh terrestrial environments, as well as some species of microorganisms, such as bacteria (Moeller et al., 2010), criptoendolithic cyanobacteria and lithic fungi (de los Ríos et al. 2004). To study the survival capacity of lichens to the harmful radiation environment of space, we have selected the lichen Circinaria gyrosa, an astrobiological model defined by its high capacity of resistance to space conditions (De la Torre et al. 2010) and to a simulated Mars environment (Sanchez et al., 2012). Samples were irradiated with four types of space-relevant ionizing radiation in the STARLIFE campaign: helium and iron ion doses (up to 2,000 Gy), X-ray doses (up to 5,000 Gy) and ultra-high γ-ray doses (from 6 to 113 kGy). Results on resistance of C. gyrosa to space-relevant ionizing radiation and its post-irradiation viability were obtained by: (i) chlorophyll a fluorescence of photosystem II (PS II); (ii) epifluorescence microscopy; (iii) confocal laser-scanning microscopy (CLSM), and (iv) field emission scanning electron microscopy (FESEM). Results of photosynthetic activity and epifluorescence showed no significant changes on the viability of C. gyrosa with increasing doses of helium and iron ions as well as X-rays. In contrast, γ-irradiation elicited significant dose-correlated effects as revealed by all applied techniques. Relevant is the presence of whewellite-like crystals, detected by FESEM on C. gyrosa thalli after high irradiation doses, which has been also identified in previous Mars simulation studies (Böttcher et al., 2014). These studies contribute to the better understanding of the adaptability of extremophile organisms to harsh environments, as well as to estimate the habitability of a planet's surface, like Mars; they will be important for planning experiments on the search of life

  17. Comparison of approximate formulas for decision levels and detection limits for paired counting with the exact results

    International Nuclear Information System (INIS)

    Potter, W.E.

    2005-01-01

    The exact probability density function for paired counting can be expressed in terms of modified Bessel functions of integral order when the expected blank count is known. Exact decision levels and detection limits can be computed in a straightforward manner. For many applications perturbing half-integer corrections to Gaussian distributions yields satisfactory results for decision levels. When there is concern about the uncertainty for the expected value of the blank count, a way to bound the errors of both types using confidence intervals for the expected blank count is discussed. (author)

  18. Detection limit improvements forecasted at CTBTO IMS radionuclide stations based on size separation of aerosols by aerodynamic diameter

    International Nuclear Information System (INIS)

    Biegalski, S.; Ezekoye, O.A.; Pena, J.M.; Waye, S.; Pickering, M.

    2008-01-01

    Studies show that aerosols with natural activity have an aerodynamic diameter in the range of 0.1 to 1 μm. In contrast, nuclear explosions generally produce radioactive aerosols with aerodynamic diameters less than 0.1 μm and greater than 1 μm. These differences in aerosol sizes are quite fortuitous because they allow aerosol aerodynamic diameter to be utilized as a physical property to separate aerosols of natural origin from those produced in a nuclear explosion. Data collected in Austin, TX and at U.S. CTBT IMS radionuclide stations have been utilized to forecast detection limit improvements possible given an aerosol size separation capability. (author)

  19. Statistical data treatment of environmental radiological measurements extracted by the CSN and submitted to a lower limit of detection

    International Nuclear Information System (INIS)

    Felipe, A.; Martin, M.; Valdes, T.

    1992-01-01

    The quantification of radiological environmental contamination is usually carried out by mean of sample measurements around the emission points. These data are submitted to the so called Lower Limit of Detection which makes data to be statistically censored. The following topics have been included in our work: (a) Correction of mean values of the radiological contamination levels by the estimation of its distribution. (b) Development of the computer programs to carry out the former correction of estimators. (c) Estimation of the existing correlation among the different types of measurements. (author)

  20. Estimation of the detection limit of an experimental model of tritium storage bed designed for 'in-situ' accountability

    International Nuclear Information System (INIS)

    Bulubasa, Gheorghe; Bidica, Nicolae; Stefanescu, Ioan; Bucur, Ciprian; Deaconu, Mariea

    2009-01-01

    During the water detritiation process most of the tritium inventory is transferred from water into the gaseous phase, then it is further enriched and finally extracted and safely stored. The control of tritium inventory is an acute issue from several points of view: - Financially - tritium is an expensive material; - Safeguard - tritium is considered as nuclear material of strategic importance; - Safety - tritium is a radioactive material: requirements for documented safety analysis report (to ensure strict limits on the total tritium allowed) and for evaluation of accident consequences associated with that inventory. Large amounts of tritium can be stored, in a very safely manner, as metal tritides. A bench-scale experiment of a tritium storage bed with integrated system for in-situ tritium inventory accountancy was designed and developed at ICSI Rm. Valcea. The calibration curve and the detection limit for this experimental model of tritium storage bed were determined. The experimental results are presented in this paper. (authors)

  1. [THE INFLUENCE OF THE PREPARATION PRETREATMENT ON IN SITU DETECTION OF 5-METHYLCYTOSINE IN METAPHASE CHROMOSOMES AND IN INTERPHASE NUCLEI].

    Science.gov (United States)

    Grudinina, N A; Sasina, L K; Noniashvili, E M; Neronova, E G; Pavlinova, L I; Suchkova, I O; Sofronov, G A; Patkin, E L

    2015-01-01

    Qualitative and quantitate analysis of DNA methylation in situ at the level of cells, chromosomes and chromosomal domains is extremely important for the diagnosis and treatment of various diseases, the study of ageing and the consequences of environmental impacts. An important question arises, whether the revealed in situ methylation pattern reflects DNA methylation per se and (or) availability of the DNA for antibodies, which in turn depends on the peculiarities of chromatin structure and chromosome condensation. These events can lead to an incorrect evaluation of the actual pattern of DNA methylation. To avoid this shortcoming as far as possible, we have modified the most widely used method of revealing 5-methylcytosine in situ with monoclonal antibodies. Here we have shown that the detection of DNA methylation staining of chromosomes including C-heterochromatin, chromosomal arms and sister chromatids is drastically dependent on pretreatment of chromosomal preparations for immunocytochemical study using fluorescent antibodies. Using undifferentiated stem cells of mouse embryonal carcinoma line F9, it has been found that change in preparations storage results in a sharp fluorescence decrease up to complete disappearance of the signal in centromeric heterochromatin. With the help of the method described in the work, we have first revealed the asymmetry of sister chromatids methylation in metaphase chromosomes of F9 cell and lymphocytes of human periphery blood. This may lead to asymmetry of transcriptional signature of daughter cells after division. The proposed here modification of 5-methylcytosine detection in situ provides a more complete characterization of methylation of chromosomes and chromosomal domains, compared to previously published methods.

  2. Astrophysical limitations to the identification of dark matter: Indirect neutrino signals vis-a-vis direct detection recoil rates

    International Nuclear Information System (INIS)

    Serpico, Pasquale D.; Bertone, Gianfranco

    2010-01-01

    A convincing identification of dark matter (DM) particles can probably be achieved only through a combined analysis of different detections strategies, which provides an effective way of removing degeneracies in the parameter space of DM models. In practice, however, this program is made complicated by the fact that different strategies depend on different physical quantities, or on the same quantities but in a different way, making the treatment of systematic errors rather tricky. We discuss here the uncertainties on the recoil rate in direct-detection experiments and on the muon rate induced by neutrinos from dark matter annihilations in the Sun, and we show that, contrarily to the local DM density or overall cross section scale, irreducible astrophysical uncertainties affect the two rates in a different fashion, therefore limiting our ability to reconstruct the parameters of the dark matter particles. By varying within their respective errors astrophysical parameters such as the escape velocity and the velocity dispersion of dark matter particles, we show that the uncertainty on the relative strength of the neutrino and direct-detection signal is as large as a factor of 2 for typical values of the parameters, but can be even larger in some circumstances.

  3. A quantitative method for determining a representative detection limit of the forensic luminol test for latent bloodstains.

    Science.gov (United States)

    Cassidy, Brianna M; Lu, Zhenyu; Martin, Jennifer P; Tazik, Shawna K; Kellogg, Katie W; DeJong, Stephanie A; Belliveau, Elle O; Kilgore, Katherine E; Ervin, Samantha M; Meece-Rayle, Mackenzie; Abraham, Alyssa M; Myrick, Michael L; Morgan, Stephen L

    2017-09-01

    The luminol test has been used for over 60 years by forensic investigators for presumptive identification of blood and visualization of blood splatter patterns. Multiple studies have estimated the limit of detection (LD) for bloodstains when luminol is employed, with results ranging from 100× to 5,000,000× dilute. However, these studies typically have not identified and controlled important experimental variables which may affect the luminol LD for bloodstains. Without control of experimental parameters in the laboratory, variables which affect the potential of presumptive bloodstain test methods remain largely unknown, and comparisons required to establish new, more powerful detection methods are simply impossible. We have developed a quantitative method to determine the relationship between the amount of blood present and its reaction with luminol by measuring, under controlled conditions, the resulting chemiluminescent intensity with a video camera, combined with processing of the digital intensity data. The method resulted in an estimated LD for bloodstains on cotton fabric at ∼200,000× diluted blood with a specific luminol formulation. Although luminol is the focus of this study, the experimental protocol used could be modified to study effects of variables using other blood detection reagents. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Does parallel item content on WOMAC's Pain and Function Subscales limit its ability to detect change in functional status?

    Directory of Open Access Journals (Sweden)

    Kennedy Deborah M

    2004-06-01

    Full Text Available Abstract Background Although the Western Ontario and McMaster University Osteoarthritis Index (WOMAC is considered the leading outcome measure for patients with osteoarthritis of the lower extremity, recent work has challenged its factorial validity and the physical function subscale's ability to detect valid change when pain and function display different profiles of change. This study examined the etiology of the WOMAC's physical function subscale's limited ability to detect change in the presence of discordant changes for pain and function. We hypothesized that the duplication of some items on the WOMAC's pain and function subscales contributed to this shortcoming. Methods Two eight-item physical function scales were abstracted from the WOMAC's 17-item physical function subscale: one contained activities and themes that were duplicated on the pain subscale (SIMILAR-8; the other version avoided overlapping activities (DISSIMILAR-8. Factorial validity of the shortened measures was assessed on 310 patients awaiting hip or knee arthroplasty. The shortened measures' abilities to detect change were examined on a sample of 104 patients following primary hip or knee arthroplasty. The WOMAC and three performance measures that included activity specific pain assessments – 40 m walk test, stair test, and timed-up-and-go test – were administered preoperatively, within 16 days of hip or knee arthroplasty, and at an interval of greater than 20 days following the first post-surgical assessment. Standardized response means were used to quantify change. Results The SIMILAR-8 did not demonstrate factorial validity; however, the factorial structure of the DISSIMILAR-8 was supported. The time to complete the performance measures more than doubled between the preoperative and first postoperative assessments supporting the theory that lower extremity functional status diminished over this interval. The DISSIMILAR-8 detected this deterioration in functional

  5. The use of a European coinage alloy to compare the detection limits of mobile XRF systems. A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Cesareo, R. [Struttura Dipartimentale di Matematica e Fisica, Universita di Sassari, Sassari (Italy); Ferretti, M. [CNR-Istituto per le Tecnologie Applicate ai Beni Culturali, Rome (Italy); Gigante, G.E. [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Rome (Italy); Guida, G. [Laboratorio di Chimica, Istituto Centrale per il Restauro, Rome (Italy); Moioli, P. [Unita Tecnico-Scientifica Materiali e Nuove Tecnologie, ENEA, Rome (Italy); Ridolfi, S. [Ars Mensurae, Rome (Italy); Roldan Garcia, C. [Unidad de Arqueometria, Instituto de Ciencia de Materiales, Universidad de Valencia, Valencia (Spain)

    2007-05-15

    The investigation of archaeological and historical materials makes use of techniques that, though borrowed from other fields of research and industrial production, frequently have to be 're-invented' because of peculiar characteristics of the analysed objects. Artistic relevance, limited movability, compositional and structural heterogeneity radically change the experimental approach and often require ad hoc designed equipment. These considerations also apply to x-ray fluorescence, especially regarding mobile systems. The extensive development and use of mobile spectrometers has produced an extremely diversified context and created the need for common criteria to evaluate their performances as well as the advisability of a survey on the existing equipment. This paper shows the feasibility of such an idea through a demonstrative survey that was carried out among users of different mobile x-ray fluorescence spectrometry (XRF) systems in the areas of Rome, Italy and Valencia, Spain. The experimental protocol was based on measuring spectrometer detection limits with the single standard method. The standard was the 50 Euro-cent coin, whose alloy is made of 89% Cu, 5% Al, 5% Zn, 1% Sn; the large spread of the European currency guarantees maximum availability. The experimental data show that the use of different x-ray tubes and detectors results in detection limits that may differ from each other by a factor of 6 for Zn and almost 100 for Sn; despite the large number of variables that in principle affect the performance, it was observed that the high voltage of the x-ray tube is the most important parameter. (authors)

  6. Coincidence detection of single-photon responses in the inner retina at the sensitivity limit of vision.

    Science.gov (United States)

    Ala-Laurila, Petri; Rieke, Fred

    2014-12-15

    Vision in starlight relies on our ability to detect single absorbed photons. Indeed, the sensitivity of dark-adapted vision approaches limits set by the quantal nature of light. This sensitivity requires neural mechanisms that selectively transmit quantal responses and suppress noise. Such mechanisms face an inevitable tradeoff because signal and noise cannot be perfectly separated, and rejecting noise also means rejecting signal. We report measurements of single-photon responses in the output signals of the primate retina. We find that visual signals arising from a few absorbed photons are read out fundamentally differently by primate On and Off parasol ganglion cells, key retinal output neurons. Off parasol cells respond linearly to near-threshold flashes, retaining sensitivity to each absorbed photon but maintaining a high level of noise. On parasol cells respond nonlinearly due to thresholding of their excitatory synaptic inputs. This nonlinearity reduces neural noise but also limits information about single-photon absorptions. The long-standing idea that information about each photon absorption is available for behavior at the sensitivity limit of vision is not universally true across retinal outputs. More generally, our work shows how a neural circuit balances the competing needs for sensitivity and noise rejection. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. A LIMIT ON THE NUMBER OF ISOLATED NEUTRON STARS DETECTED IN THE ROSAT ALL-SKY-SURVEY BRIGHT SOURCE CATALOG

    International Nuclear Information System (INIS)

    Turner, Monica L.; Rutledge, Robert E.; Letcavage, Ryan; Shevchuk, Andrew S. H.; Fox, Derek B.

    2010-01-01

    Using new and archival observations made with the Swift satellite and other facilities, we examine 147 X-ray sources selected from the ROSAT All-Sky-Survey Bright Source Catalog (RASS/BSC) to produce a new limit on the number of isolated neutron stars (INSs) in the RASS/BSC, the most constraining such limit to date. Independent of X-ray spectrum and variability, the number of INSs is ≤48 (90% confidence). Restricting attention to soft (kT eff < 200 eV), non-variable X-ray sources-as in a previous study-yields an all-sky limit of ≤31 INSs. In the course of our analysis, we identify five new high-quality INS candidates for targeted follow-up observations. A future all-sky X-ray survey with eROSITA, or another mission with similar capabilities, can be expected to increase the detected population of X-ray-discovered INSs from the 8-50 in the BSC, to (for a disk population) 240-1500, which will enable a more detailed study of neutron star population models.

  8. Matrix effect on the detection limit and accuracy in total reflection X-ray fluorescence analysis of trace elements in environmental and biological samples

    International Nuclear Information System (INIS)

    Karjou, J.

    2007-01-01

    The effect of matrix contents on the detection limit of total reflection X-ray fluorescence analysis was experimentally investigated using a set of multielement standard solutions (500 ng/mL of each element) in variable concentrations of NH 4 NO 3 . It was found that high matrix concentration, i.e. 0.1-10% NH 4 NO 3 , had a strong effect on the detection limits for all investigated elements, whereas no effect was observed at lower matrix concentration, i.e. 0-0.1% NH 4 NO 3 . The effect of soil and blood sample masses on the detection limit was also studied. The results showed decreasing the detection limit (in concentration unit, μg/g) with increasing the sample mass. However, the detection limit increased (in mass unit, ng) with increasing sample mass. The optimal blood sample mass of ca. 200 μg was sufficient to improve the detection limit of Se determination by total reflection X-ray fluorescence. The capability of total reflection X-ray fluorescence to analyze different kinds of samples was discussed with respect to the accuracy and detection limits based on certified and reference materials. Direct analysis of unknown water samples from several sources was also presented in this work

  9. Preparation and characterization of gadolinium-loaded PLGA particles surface modified with RGDS for the detection of thrombus

    Directory of Open Access Journals (Sweden)

    Zhang Y

    2013-10-01

    Full Text Available Yu Zhang,1 Jun Zhou,1 Dajing Guo,1 Meng Ao,2 Yuanyi Zheng,2 Zhigang Wang21Department of Radiology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China; 2Institute of Ultrasound Imaging, Department of Ultrasound, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of ChinaAbstract: Thrombotic disease is a leading cause of death and disability worldwide. The development of magnetic resonance molecular imaging provides potential promise for early disease diagnosis. In this study, we explore the preparation and characterization of gadolinium (Gd-loaded poly (lactic-co-glycolic acid (PLGA particles surface modified with the Arg-Gly-Asp-Ser (RGDS peptide for the detection of thrombus. PLGA was employed as the carrier-delivery system, and a double emulsion solvent-evaporation method (water in oil in water was used to prepare PLGA particles encapsulating the magnetic resonance contrast agent Gd diethylenetriaminepentaacetic acid (DTPA. To synthesize the Gd-PLGA/chitosan (CS-RGDS particles, carbodiimide-mediated amide bond formation was used to graft the RGDS peptide to CS to form a CS-RGDS film that coated the surface of the PLGA particles. Blank PLGA, Gd-PLGA, and Gd-PLGA/CS particles were fabricated using the same water in oil in water method. Our results indicated that the RGDS peptide successfully coated the surface of the Gd-PLGA/CS-RGDS particles. The particles had a regular shape, smooth surface, relatively uniform size, and did not aggregate. The high electron density of the Gd-loaded particles and a translucent film around the particles coated with the CS and CS-RGDS films could be observed by transmission electron microscopy. In vitro experiments demonstrated that the Gd-PLGA/CS-RGDS particles could target thrombi and could be imaged using a clinical magnetic resonance scanner. Compared with the Gd-DTPA solution, the longitudinal relaxation time of

  10. Attempts to lower the detection limits of heavy metals in standardized grass cultures by using alternative growth substrates

    International Nuclear Information System (INIS)

    Winter, A.; Mueller, P.; Wagner, G.

    1992-01-01

    In addition to the use of standardized grass cultures (cf. VDI 3792) within the framework of an effect cadastre, grass cultures were tested on two non-contaminated substrates with nutrient solution in the greenhouse and in the open land during different exposure cycles. The results: As compared to the standard cultures on standardized soil, the cultures have the same or a better growth performance and better dry resistance on the artificial substrates; the blind values and the refore the detection limits in particular for cadmium are by far lower; four-week exposure periods with a two-week overlap have an improved information yield for the same amount of work throughout the investigation period as compared to a two-week exposure. Recommendations are derived from the results for a simplified application of the grass culture method in practice. (orig.) [de

  11. Using rapid-scan EPR to improve the detection limit of quantitative EPR by more than one order of magnitude.

    Science.gov (United States)

    Möser, J; Lips, K; Tseytlin, M; Eaton, G R; Eaton, S S; Schnegg, A

    2017-08-01

    X-band rapid-scan EPR was implemented on a commercially available Bruker ELEXSYS E580 spectrometer. Room temperature rapid-scan and continuous-wave EPR spectra were recorded for amorphous silicon powder samples. By comparing the resulting signal intensities the feasibility of performing quantitative rapid-scan EPR is demonstrated. For different hydrogenated amorphous silicon samples, rapid-scan EPR results in signal-to-noise improvements by factors between 10 and 50. Rapid-scan EPR is thus capable of improving the detection limit of quantitative EPR by at least one order of magnitude. In addition, we provide a recipe for setting up and calibrating a conventional pulsed and continuous-wave EPR spectrometer for rapid-scan EPR. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Chlorine-trapped CVD bilayer graphene for resistive pressure sensor with high detection limit and high sensitivity

    Science.gov (United States)

    Phuong Pham, Viet; Triet Nguyen, Minh; Park, Jin Woo; Kwak, Sung Soo; Nguyen, Dieu Hien Thi; Kyeom Mun, Mu; Danh Phan, Hoang; San Kim, Doo; Kim, Ki Hyun; Lee, Nae-Eung; Yeom, Geun Young

    2017-06-01

    Pressure sensing is one of the key functions for smart electronics. Considerably more effort is required to achieve the fabrication of pressure sensors that can imitate and overcome the sophisticated pressure sensing characteristics in nature and industry, especially in the innovation of materials and structures. Almost all of the pressure sensors reported until now have a high sensitivity at a low-pressure detection limit (type chlorine trap doping in the channel graphene with chlorine radicals without damaging the graphene. This work indicates that the ZGClG channel used for the pressure sensing device could also provide a simple and essential sensing platform for chemical-, medical-, and biological-sensing for future smart electronics.

  13. Limit of detection and threshold for positivity of the Centers for Disease Control and Prevention assay for factor VIII inhibitors.

    Science.gov (United States)

    Miller, C H; Boylan, B; Shapiro, A D; Lentz, S R; Wicklund, B M

    2017-10-01

    Essentials Immunologic methods detect factor VIII (FVIII) antibodies in some inhibitor-negative specimens. Specimens were tested by modified Nijmegen-Bethesda assay (NBA) and fluorescence immunoassay. The NBA with preanalytical heat inactivation detects FVIII inhibitors down to 0.2 NBU. IgG 4 frequency validates the established threshold for positivity of ≥ 0.5 NBU for this NBA. Background The Bethesda assay for measurement of factor VIII inhibitors called for quantification of positive inhibitors by using dilutions producing 25-75% residual activity (RA), corresponding to 0.4-2.0 Bethesda units, with the use of 'more sensitive methods' for samples with RA closer to 100% being recommended. The Nijmegen modification (Nijmegen-Bethesda assay [NBA]) changed the reagents used but not these calculations. Some specimens negative by the NBA have been shown to have FVIII antibodies detectable with sensitive immunologic methods. Objective To examine the performance at very low inhibitor titers of the Centers for Disease Control and Prevention (CDC)-modified NBA (CDC-NBA), which includes preanalytic heat inactivation to liberate bound anti-FVIII antibodies. Methods Specimens with known inhibitors were tested with the CDC-NBA. IgG 4 anti-FVIII antibodies were measured by fluorescence immunoassay (FLI). Results Diluted inhibitors showed linearity below 0.4 Nijmegen-Bethesda units (NBU). With four statistical methods, the limit of detection of the CDC-NBA was determined to be 0.2 NBU. IgG 4 anti-FVIII antibodies, which correlate most strongly with functional inhibitors, were present at rates above the background rate of healthy controls in specimens with titers ≥ 0.2 NBU and showed an increase in frequency from 14.3% at 0.4 NBU to 67% at the established threshold for positivity of 0.5 NBU. Conclusions The CDC-NBA can detect inhibitors down to 0.2 NBU. The FLI, which is more sensitive, demonstrates anti-FVIII IgG 4 in some patients with negative (NBA, supporting the need for

  14. Upper limits to the detection of ammonia from protoplanetary disks around HL Tauri and L1551-IRS 5

    Science.gov (United States)

    Gomez, Jose F.; Torrelles, Jose M.; Ho, Paul T. P.; Rodriguez, Luis F.; Canto, Jorge

    1993-01-01

    We present NH3(1, 1) and (2, 2) observations of the young stellar sources HL Tau and L1551-IRS 5 using the VLA in its B-configuration, which provides an angular resolution of about 0.4 arcsec (about 50 AU at 140 pc) at 1.3 cm wavelength. Our goal was to detect and resolve circumstellar molecular disks with radius of the order of 100 AU around these two sources. No ammonia emission was detected toward either of them. The 3-sigma levels were 2.7 mJy/beam and 3.9 mJy/beam for HL Tau and L1551-IRS 5, respectively, with a velocity resolution of about 5 km/s. With this nondetection, we estimate upper limits to the mass of the proposed protoplanetary molecular disks (within a radius of 10 AU from the central stars) on the order of 0.02/(X(NH3)/10 exp -8) solar mass for HL Tau and 0.1/(X(NH3)/10 exp -8) solar mass for L1551-IRS 5.

  15. Quantifying Efficacy and Limits of Unmanned Aerial Vehicle (UAV Technology for Weed Seedling Detection as Affected by Sensor Resolution

    Directory of Open Access Journals (Sweden)

    José M. Peña

    2015-03-01

    Full Text Available In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera, spatial (flight altitude and temporal (the date of the study resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2, when plants had 5–6 true leaves, had the highest weed detection accuracy (up to 91%. At this flight altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations.

  16. Quantifying efficacy and limits of unmanned aerial vehicle (UAV) technology for weed seedling detection as affected by sensor resolution.

    Science.gov (United States)

    Peña, José M; Torres-Sánchez, Jorge; Serrano-Pérez, Angélica; de Castro, Ana I; López-Granados, Francisca

    2015-03-06

    In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV) for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera), spatial (flight altitude) and temporal (the date of the study) resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2), when plants had 5-6 true leaves, had the highest weed detection accuracy (up to 91%). At this flight altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing) because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations.

  17. Changes in respiratory function impairment following the treatment of severe pulmonary tuberculosis - limitations for the underlying COPD detection.

    Science.gov (United States)

    Radovic, Milan; Ristic, Lidija; Ciric, Zorica; Dinic-Radovic, Violeta; Stankovic, Ivana; Pejcic, Tatjana; Rancic, Milan; Bogdanovic, Dragan

    2016-01-01

    During the treatment phase of active pulmonary tuberculosis (PTB), respiratory function impairment is usually restrictive. This may become obstructive, as a PTB-associated airflow obstruction (AFO) or as a later manifestation of underlying COPD. The aim of the study was to examine the potential causes and risks for AFO development in PTB by exploring the aspects of spirometry limitations and clinical implications for the underlying COPD detection, taking into account various confounding factors. Prospective, nest case-control study on 40 new cases of PTB with initial restrictive respiratory function impairment, diagnosed and treated according to the directly observed treatment short course (DOTS) strategy. From all observed patients, 37.5% of them developed AFO upon the completion of PTB treatment, with significantly increased average of forced vital capacity (%) (Ppulmonary tuberculosis lesions (OR 1.01-1.05 for 95% CI; P=0.02) and sputum conversion rate on culture (OR 1.02-1.68 for 95% CI; P=0.04) as the most significant predictors for the risk of AFO development. AFO upon PTB treatment is a common manifestation of underlying COPD, which mostly occurs later, during the reparative processes in active PTB, even in the absence of major risk factors, such as cigarette smoking and biomass fuel dust exposure. Initial spirometry testing in patients with active PTB is not a sufficient and accurate approach in the detection of underlying COPD, which may lead to their further potential health deterioration.

  18. Advantages and Limitations of Androgen Receptor-Based Methods for Detecting Anabolic Androgenic Steroid Abuse as Performance Enhancing Drugs

    Science.gov (United States)

    Bailey, Kathy; Yazdi, Tahmineh; Masharani, Umesh; Tyrrell, Blake; Butch, Anthony; Schaufele, Fred

    2016-01-01

    Testosterone (T) and related androgens are performance enhancing drugs (PEDs) abused by some athletes to gain competitive advantage. To monitor unauthorized androgen abuse, doping control programs use mass spectrometry (MS) to detect androgens, synthetic anabolic-androgenic steroids (AASs) and their metabolites in an athlete’s urine. AASs of unknown composition will not be detected by these procedures. Since AASs achieve their anabolic effects by activating the Androgen Receptor (AR), cell-based bioassays that measure the effect of a urine sample on AR activity are under investigation as complementary, pan-androgen detection methods. We evaluated an AR BioAssay as a monitor for androgen activity in urine pre-treated with glucuronidase, which releases T from the inactive T-glucuronide that predominates in urine. AR BioAssay activity levels were expressed as ‘T-equivalent’ concentrations by comparison to a T dose response curve. The T-equivalent concentrations of androgens in the urine of hypogonadal participants supplemented with T (in whom all androgenic activity should arise from T) were quantitatively identical to the T measurements conducted by MS at the UCLA Olympic Analytical Laboratory (0.96 ± 0.22). All 17 AASs studied were active in the AR BioAssay; other steroids were inactive. 12 metabolites of 10 commonly abused AASs, which are used for MS monitoring of AAS doping because of their prolonged presence in urine, had reduced or no AR BioAssay activity. Thus, the AR BioAssay can accurately and inexpensively monitor T, but its ability to monitor urinary AASs will be limited to a period immediately following doping in which the active AASs remain intact. PMID:26998755

  19. Advantages and Limitations of Androgen Receptor-Based Methods for Detecting Anabolic Androgenic Steroid Abuse as Performance Enhancing Drugs.

    Science.gov (United States)

    Bailey, Kathy; Yazdi, Tahmineh; Masharani, Umesh; Tyrrell, Blake; Butch, Anthony; Schaufele, Fred

    2016-01-01

    Testosterone (T) and related androgens are performance enhancing drugs (PEDs) abused by some athletes to gain competitive advantage. To monitor unauthorized androgen abuse, doping control programs use mass spectrometry (MS) to detect androgens, synthetic anabolic-androgenic steroids (AASs) and their metabolites in an athlete's urine. AASs of unknown composition will not be detected by these procedures. Since AASs achieve their anabolic effects by activating the Androgen Receptor (AR), cell-based bioassays that measure the effect of a urine sample on AR activity are under investigation as complementary, pan-androgen detection methods. We evaluated an AR BioAssay as a monitor for androgen activity in urine pre-treated with glucuronidase, which releases T from the inactive T-glucuronide that predominates in urine. AR BioAssay activity levels were expressed as 'T-equivalent' concentrations by comparison to a T dose response curve. The T-equivalent concentrations of androgens in the urine of hypogonadal participants supplemented with T (in whom all androgenic activity should arise from T) were quantitatively identical to the T measurements conducted by MS at the UCLA Olympic Analytical Laboratory (0.96 ± 0.22). All 17 AASs studied were active in the AR BioAssay; other steroids were inactive. 12 metabolites of 10 commonly abused AASs, which are used for MS monitoring of AAS doping because of their prolonged presence in urine, had reduced or no AR BioAssay activity. Thus, the AR BioAssay can accurately and inexpensively monitor T, but its ability to monitor urinary AASs will be limited to a period immediately following doping in which the active AASs remain intact.

  20. Diagnostic accuracy of the detection of bone change using panoramic TMJ projection. Comparative study with limited cone-beam CT

    International Nuclear Information System (INIS)

    Araki, Kazuyuki; Okano, Tomohiro; Kataoka, Ryuta; Honda, Kazuya; Endo, Atsushi; Kaneko, Norikazu; Funahashi, Itsuo

    2008-01-01

    Panoramic temporoman joint (TMJ) projection is one of the alternative methods of conventional radiography, such as transcranial projection, for diagnosing temporomandibular joint disorder. There have been a few reports describing the diagnostic ability of this method. We evaluated the diagnostic accuracy of detecting bone change with panoramic TMJ projection. Fifty TMJs in 25 patients were examined. All TMJs were examined by panoramic TMJ projection (Hyper XF) and limited cone-beam CT (3D Accuitomo FPD; 3DX). Two observers evaluated the presence of bone change in the TMJ region using panoramic TMJ projection. One other observer evaluated the limited cone-beam CT for the presence and the pattern of bone changes in the TMJ region as the gold standard. Panoramic TMJ findings were evaluated with regard to sensitivity, specificity, and accuracy. Sensitivity, specificity and accuracy of the panoramic TMJ projection were 0.86, 0.76, and 0.82, respectively. These results and those of previous reports on other radiographic methods for TMJ suggest that panoramic TMJ projection is a useful method of screening for bone change due to TMJ disorder. (author)

  1. One-pot preparation of conducting composite containing abundant amino groups on electrode surface for electrochemical detection of von willebrand factor

    Science.gov (United States)

    Wang, Wen; Ma, Chao; Li, Yi; Liu, Baihui; Tan, Liang

    2018-03-01

    A one-pot protocol based on cyclic voltammetric scan was employed to prepare new conducting composite that was abundant in amino groups. The scanning electron microscope, atomic force microscope, X-ray photoelectron spectroscopy and infrared spectrum characterization demonstrate that poly(azure A), gold nanoparticles, chitosan and cysteine were immobilized simultaneously on glassy carbon electrode surface. Von Willebrand factor (vWF) antibody (Ab) was subsequently assembled by using glutaraldehyde to construct the Ab/composite-modified electrode. The capture of vWF could inhibit the charge transfer between the ferri-/ferrocyanide probe and the electrode and exert the negative effect on the electrochemical response of the dye polymer in the conducting composite due to the strong steric hindrance effect. The DPV peak current change before and after the immunoreaction was found to be proportional to the logarithm of the vWF concentration from 0.001 to 100 μg mL-1 with a detection limit of 0.4 ng mL-1. The proposed label-free electrochemical method was employed in the investigation on the release of vWF by oxidation-injured vascular endothelial cells. The experimental results exhibit that the vWF content in growth medium was increased when the oxidation injury of the cells was intensified in the presence of H2O2.

  2. Preparation of carbon quantum dots from cigarette filters and its application for fluorescence detection of Sudan I.

    Science.gov (United States)

    Anmei, Su; Qingmei, Zhong; Yuye, Chen; Yilin, Wang

    2018-09-06

    Carbon quantum dots (CQDs) with quantum yield of 14% were successfully synthesized via a simple, low-cost, and green hydrothermal treatment using cigarette filters as carbon source for the first time. The obtained CQDs showed a strong emission at the wavelength of 465 nm, with an optimum excitation of 365 nm.Sudan I with maximum absorption wavelength at 477 nm could selectively quench the fluorescence of CQDs. Based on this principle, a fluorescence probe was developed for Sudan I determination. Furthermore, the quenching mechanism of the CQDs was elucidated. A linear relationship was found in the range of 2.40-104.0 μmol/L Sudan I with the detection limit (3σ/k) of 0.95 μmol/L. Satisfactory results were achieved when the method was submitted to the determination of Sudan I in food samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Ultrathin Two-Dimensional Covalent Organic Framework Nanosheets: Preparation and Application in Highly Sensitive and Selective DNA Detection

    KAUST Repository

    Peng, Yongwu; Huang, Ying; Zhu, Yihan; Chen, Bo; Wang, Liying; Lai, Zhuangchai; Zhang, Zhicheng; Zhao, Meiting; Tan, Chaoliang; Yang, Nailiang; Shao, Fangwei; Han, Yu; Zhang, Hua

    2017-01-01

    The ability to prepare ultrathin two-dimensional (2D) covalent organic framework (COF) nanosheets (NSs) in high yield is of great importance for the further exploration of their unique properties and potential applications. Herein, by elaborately designing and choosing two flexible molecules with C3v molecular symmetry as building units, a novel imine-linked COF, namely TPA-COF, with hexagonal layered structure and sheet-like morphology, is synthesized. Since the flexible building units are integrated into the COF skeletons, the interlayer stacking becomes weak, resulting in the easy exfoliation of TPA-COF into ultrathin 2D NSs. Impressively, for the first time, the detailed structural information, i.e. the pore channels and individual building units in the NSs, is clearly visualized by using the recently developed low-dose imaging technique of transmission electron microscopy (TEM). As a proof-of-concept application, the obtained ultrathin COF NSs are used as a novel fluorescence sensing platform for the highly sensitive and selective detection of DNA.

  4. Ultrathin Two-Dimensional Covalent Organic Framework Nanosheets: Preparation and Application in Highly Sensitive and Selective DNA Detection.

    Science.gov (United States)

    Peng, Yongwu; Huang, Ying; Zhu, Yihan; Chen, Bo; Wang, Liying; Lai, Zhuangchai; Zhang, Zhicheng; Zhao, Meiting; Tan, Chaoliang; Yang, Nailiang; Shao, Fangwei; Han, Yu; Zhang, Hua

    2017-06-28

    The ability to prepare ultrathin two-dimensional (2D) covalent organic framework (COF) nanosheets (NSs) in high yield is of great importance for the further exploration of their unique properties and potential applications. Herein, by elaborately designing and choosing two flexible molecules with C 3v molecular symmetry as building units, a novel imine-linked COF, namely, TPA-COF, with a hexagonal layered structure and sheet-like morphology, is synthesized. Since the flexible building units are integrated into the COF skeletons, the interlayer stacking becomes weak, resulting in the easy exfoliation of TPA-COF into ultrathin 2D NSs. Impressively, for the first time, the detailed structural information, i.e., the pore channels and individual building units in the NSs, is clearly visualized by using the recently developed low-dose imaging technique of transmission electron microscopy (TEM). As a proof-of-concept application, the obtained ultrathin COF NSs are used as a novel fluorescence sensing platform for the highly sensitive and selective detection of DNA.

  5. Ultrathin Two-Dimensional Covalent Organic Framework Nanosheets: Preparation and Application in Highly Sensitive and Selective DNA Detection

    KAUST Repository

    Peng, Yongwu

    2017-06-03

    The ability to prepare ultrathin two-dimensional (2D) covalent organic framework (COF) nanosheets (NSs) in high yield is of great importance for the further exploration of their unique properties and potential applications. Herein, by elaborately designing and choosing two flexible molecules with C3v molecular symmetry as building units, a novel imine-linked COF, namely TPA-COF, with hexagonal layered structure and sheet-like morphology, is synthesized. Since the flexible building units are integrated into the COF skeletons, the interlayer stacking becomes weak, resulting in the easy exfoliation of TPA-COF into ultrathin 2D NSs. Impressively, for the first time, the detailed structural information, i.e. the pore channels and individual building units in the NSs, is clearly visualized by using the recently developed low-dose imaging technique of transmission electron microscopy (TEM). As a proof-of-concept application, the obtained ultrathin COF NSs are used as a novel fluorescence sensing platform for the highly sensitive and selective detection of DNA.

  6. Preparation and characterization of AuNPs/CNTs-ErGO electrochemical sensors for highly sensitive detection of hydrazine.

    Science.gov (United States)

    Zhao, Zhenting; Sun, Yongjiao; Li, Pengwei; Zhang, Wendong; Lian, Kun; Hu, Jie; Chen, Yong

    2016-09-01

    A highly sensitive electrochemical sensor of hydrazine has been fabricated by Au nanoparticles (AuNPs) coating of carbon nanotubes-electrochemical reduced graphene oxide composite film (CNTs-ErGO) on glassy carbon electrode (GCE). Cyclic voltammetry and potential amperometry have been used to investigate the electrochemical properties of the fabricated sensors for hydrazine detection. The performances of the sensors were optimized by varying the CNTs to ErGO ratio and the quantity of Au nanoparticles. The results show that under optimal conditions, a sensitivity of 9.73μAμM(-1)cm(-2), a short response time of 3s, and a low detection limit of 0.065μM could be achieved with a linear concentration response range from 0.3μM to 319μM. The enhanced electrochemical performances could be attributed to the synergistic effect between AuNPs and CNTs-ErGO film and the outstanding catalytic effect of the Au nanoparticles. Finally, the sensor was successfully used to analyse the tap water, showing high potential for practical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Hybrid graphene oxide/DAB-Am-16 dendrimer: Preparation, characterization chemical reactivity and their electrocatalytic detection of L-Dopamine

    Science.gov (United States)

    Do Carmo, Devaney Ribeiro; Fernandes, Daniela Silvestrini

    2017-09-01

    Graphene oxide (GO) was chemically modified with a poly(propylene)imine Generation 3.0 dendrimer (DAB-Am-16). The characterization, structure and properties of hybrid graphene oxide/DAB-Am-16 dendrimer was studied by Raman spectroscopy, Fourier-Transforming Infrared Spectroscopy (FT-IR), X-Ray Photoelectron Spectroscopic (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric analysis. After functionalized the hybrid material (GOD) can interact with copper and subsequently with hexacyanoferrate (III) ions (GODHCu). The GODHCu incorporated into a graphite paste electrode (20% w/w) was applied to an electrocatalytic detection of neurotransmitter L-dopamine using differential pulse voltammetry. The analytical curve showed a linear response in the concentration range from 1.0 × 10-7 to 1.0 × 10-5 mol L-1 with a corresponding equation Y(A) = 1.706 × 10-5 + 0.862 [L-dopamine] and a correlation coefficient r2 = 0.998. The detection limit was 6.36 × 10-7 mol L-1 with a relative standard deviation of ±4% (n = 3) and an amperometric sensitivity of 0.862 A/mol L-1.

  8. Amperometric detection of morphine based on poly(3,4-ethylenedioxythiophene) immobilized molecularly imprinted polymer particles prepared by precipitation polymerization

    International Nuclear Information System (INIS)

    Ho, K.-C.; Yeh, W.-M.; Tung, T.-S.; Liao, J.-Y.

    2005-01-01

    Molecular imprinting is a novel technique used for chiral separation, artificial antibodies, sensors, and assays. Typically, molecular imprinted polymers (MIPs) are monoliths with irregular shapes. However, microspherical shapes with more uniform size can be obtained by the method of precipitation polymerization, which offers a higher active surface area by manipulating its compositions. In this study, MIP particles for the target molecule, morphine, were synthesized using a precipitation polymerization method that is more facile than the previous one that produced a thermally polymerized bulk. The conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), was utilized to immobilize the MIP particles onto the indium tin oxide (ITO) glass as a MIP/PEDOT-modified electrode. The sensitivity for the MIP/PEDOT-modified electrode with MIP particles was 41.63 μA/cm 2 mM, which is more sensitive than that with non-MIP particles or that of a single PEDOT film with no incorporated particles in detecting morphine ranging from 0.1 to 2 mM. The detection limit was 0.3 mM (S/N = 3). In addition, we presented that the modified electrode can discriminate codeine that plays an interfering species

  9. Preparation of magnetic ODS-PAN thin-films for microextraction of quetiapine and clozapine in plasma and urine samples followed by HPLC-UV detection.

    Science.gov (United States)

    Li, Dan; Zou, Juan; Cai, Pei-Shan; Xiong, Chao-Mei; Ruan, Jin-Lan

    2016-06-05

    In this study, conventional thin-film microextraction (TFME) was endowed with magnetic by introducing superparamagnetic SiO2@Fe3O4 nanoparticles in thin-films. Novel magnetic octadecylsilane (ODS)-polyacrylonitrile (PAN) thin-films were prepared by spraying, and used for the microextraction of quetiapine and clozapine in plasma and urine samples, followed by the detection of HPLC-UV. The influencing factors on the extraction efficiency of magnetic ODS-PAN TFME, including pH, extraction time, desorption solvent, desorption time, and ion strength were investigated systematically. Under the optimal conditions, both analytes showed good linearity over ranges of 0.070-9.000μgmL(-1) and 0.012-9.000μgmL(-1) in plasma and urine samples, respectively, with correlation coefficients (R(2)) above 0.9990. Limits of detection (LODs) for quetiapine in plasma and urine samples were 0.013 and 0.003μgmL(-1), respectively. LODs for clozapine in plasma and urine samples were 0.015 and 0.003μgmL(-1), respectively. The relative standard deviations (RSDs) for quetiapine and clozapine were less than 9.23%. After the validation, the protocol was successfully applied for the determination of quetiapine and clozapine in patients' plasma and urine samples with satisfactory recoveries between 99-110%. The proposed magnetic ODS-PAN TFME was very simple, fast and easy to handle. It showed high potential as a powerful pretreatment technology for routine therapeutic drug monitoring (TDM) in plasma and urine samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. High throughput detection of Coxiella burnetii by real-time PCR with internal control system and automated DNA preparation

    Directory of Open Access Journals (Sweden)

    Kramme Stefanie

    2008-05-01

    Full Text Available Abstract Background Coxiella burnetii is the causative agent of Q-fever, a widespread zoonosis. Due to its high environmental stability and infectivity it is regarded as a category B biological weapon agent. In domestic animals infection remains either asymptomatic or presents as infertility or abortion. Clinical presentation in humans can range from mild flu-like illness to acute pneumonia and hepatitis. Endocarditis represents the most common form of chronic Q-fever. In humans serology is the gold standard for diagnosis but is inadequate for early case detection. In order to serve as a diagnostic tool in an eventual biological weapon attack or in local epidemics we developed a real-time 5'nuclease based PCR assay with an internal control system. To facilitate high-throughput an automated extraction procedure was evaluated. Results To determine the minimum number of copies that are detectable at 95% chance probit analysis was used. Limit of detection in blood was 2,881 copies/ml [95%CI, 2,188–4,745 copies/ml] with a manual extraction procedure and 4,235 copies/ml [95%CI, 3,143–7,428 copies/ml] with a fully automated extraction procedure, respectively. To demonstrate clinical application a total of 72 specimens of animal origin were compared with respect to manual and automated extraction. A strong correlation between both methods was observed rendering both methods suitable. Testing of 247 follow up specimens of animal origin from a local Q-fever epidemic rendered real-time PCR more sensitive than conventional PCR. Conclusion A sensitive and thoroughly evaluated real-time PCR was established. Its high-throughput mode may show a useful approach to rapidly screen samples in local outbreaks for other organisms relevant for humans or animals. Compared to a conventional PCR assay sensitivity of real-time PCR was higher after testing samples from a local Q-fever outbreak.

  11. Facile preparation of poly(methylene blue) modified carbon paste electrode for the detection and quantification of catechin

    Energy Technology Data Exchange (ETDEWEB)

    Manasa, G [Electrochemistry Research Group, Department of Chemistry, St. Joseph' s College, Lalbagh Road, Bangalore, 560027, Karnataka (India); Mascarenhas, Ronald J, E-mail: ronaldmasc2311@yahoo.co.in [Electrochemistry Research Group, Department of Chemistry, St. Joseph' s College, Lalbagh Road, Bangalore, 560027, Karnataka (India); Satpati, Ashis K [Analytical Chemistry Division, Bhabha Atomic Research Centre, Anushakthi Nagar, Trombay, Mumbai 400094, Maharashtra (India); D' Souza, Ozma J [Electrochemistry Research Group, Department of Chemistry, St. Joseph' s College, Lalbagh Road, Bangalore, 560027, Karnataka (India); Dhason, A [Soft Condensed Matter, Raman Research Institute, Sadashivnagar, Bangalore 560080, Karnataka (India)

    2017-04-01

    Free radicals are formed as byproducts of metabolism, and are highly unstable due to the presence of unpaired electrons. They readily react with other important cellular components such as DNA causing them damage. Antioxidants such as (+)-catechin (CAT), neutralize free radicals in the blood stream. Hence there is a need for detection and quantification of catechin concentration in various food sources and beverages. Electro-oxidative properties of catechin were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A carbon paste working electrode modified by electropolymerizing methylene blue (MB) was fabricated. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) techniques were used to study the surface morphology of the electrode. Quasi-reversible electron transfer reaction occurred at + 0.260 V through a diffusion controlled process. In comparison to the bare carbon paste electrode (CPE), there was a significant 5.3 times increment in anodic current sensitivity at the modified electrode at physiological pH. Our findings indicate that for the electro-oxidation of CAT, CPE is a better base material for electropolymerization of MB compared to glassy carbon electrode (GCE). Nyquist plot followed the theoretical shape, indicating low interfacial charge transfer resistance of 0.095 kΩ at the modified electrode. Calibration plots obtained by DPV were linear in two ranges of 1.0 × 10{sup −3} to 1.0 × 10{sup −6} and 1.0 × 10{sup −7} to 0.1 × 10{sup −8} M. The limit of detection (LOD) and limit of quantification (LOQ) was 4.9 nM and 14 nM respectively. Application of the developed electrode was demonstrated by detecting catechin in green tea and spiked fruit juice with satisfactory recoveries. The sensor was stable, sensitive, selective and reproducible. - Highlights: • Remarkable electrocatalytic oxidation of Catechin at poly(methylene blue) modified CPE • Complete elimination of signal

  12. Separation followed by direct SERS detection of explosives on a novel black silicon multifunctional nanostructured surface prepared in a microfluidic channel

    DEFF Research Database (Denmark)

    Talian, Ivan; Hübner, Jörg

    2013-01-01

    The article describes the multifunctionality of a novel black silicon (BS) nanostructured surface covered with a thin layer of noble metal prepared in the a microfluidic channel. It is focused on the separation properties of the BS substrate with direct detection of the separated analytes utilizing...

  13. Continuous preparation of Fe{sub 3}O{sub 4} nanoparticles through Impinging Stream-Rotating Packed Bed reactor and their electrochemistry detection toward heavy metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Hong-Lei [Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan, 030051 (China); Zhou, Shao-Feng [Shanxi Province Key Laboratory of Functional Nanocomposites, North University of China, Taiyuan, 030051 (China); Gao, Jing [Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan, 030051 (China); Liu, You-Zhi, E-mail: lyzzhongxin@126.com [Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan, 030051 (China)

    2016-06-25

    We reported the continuous preparation and electrochemical behavior toward heavy metal ions of the Fe{sub 3}O{sub 4} nanoparticles (Fe{sub 3}O{sub 4} NPs). This Fe{sub 3}O{sub 4} NPs were fabricated through a novel Impinging Stream-Rotating Packed Bed reactor with a high production rate of 2.23 kg/hour. The as-prepared Fe{sub 3}O{sub 4} NPs were quasi-spherical with a mean diameter of about 10 nm and shown the characteristics of superparamagnetism with the saturated magnetization of 60.5 emu/g. The electrochemical characterization of the as-prepared Fe{sub 3}O{sub 4} NPs toward heavy metal ions were evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The results indicated that the modified electrode could be used to individual detection of Pb(II), Cu(II), Hg(II) and Cd(II). In particular, the modified electrode exhibited the selective detection toward Pb(II) with higher sensitivity of 14.9 μA/μM, while the response to Cu(II), Hg(II) and Cd(II) were negligible. Besides, the modified electrode shown good stability and potential practical applicability in the electrochemical determination of Pb(II). This above results offered a simple method for continuous preparation sensing materials in the application field of electrochemical detection of toxic metal ions through the technology of process intensification. - Highlights: • Fe{sub 3}O{sub 4} nanoparticles were continuous prepared through IS-RPB reactor. • The Fe{sub 3}O{sub 4} nanoparticles showed selective detection of heavy metal ions. • It exhibited favorable sensitivity (14.9 μA μM{sup −1}) and LOD (0.119 μM) for Pb(II). • The as-prepared nanoparticles showed favorable potential application.

  14. Continuous preparation of Fe3O4 nanoparticles through Impinging Stream-Rotating Packed Bed reactor and their electrochemistry detection toward heavy metal ions

    International Nuclear Information System (INIS)

    Fan, Hong-Lei; Zhou, Shao-Feng; Gao, Jing; Liu, You-Zhi

    2016-01-01

    We reported the continuous preparation and electrochemical behavior toward heavy metal ions of the Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs). This Fe 3 O 4 NPs were fabricated through a novel Impinging Stream-Rotating Packed Bed reactor with a high production rate of 2.23 kg/hour. The as-prepared Fe 3 O 4 NPs were quasi-spherical with a mean diameter of about 10 nm and shown the characteristics of superparamagnetism with the saturated magnetization of 60.5 emu/g. The electrochemical characterization of the as-prepared Fe 3 O 4 NPs toward heavy metal ions were evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The results indicated that the modified electrode could be used to individual detection of Pb(II), Cu(II), Hg(II) and Cd(II). In particular, the modified electrode exhibited the selective detection toward Pb(II) with higher sensitivity of 14.9 μA/μM, while the response to Cu(II), Hg(II) and Cd(II) were negligible. Besides, the modified electrode shown good stability and potential practical applicability in the electrochemical determination of Pb(II). This above results offered a simple method for continuous preparation sensing materials in the application field of electrochemical detection of toxic metal ions through the technology of process intensification. - Highlights: • Fe 3 O 4 nanoparticles were continuous prepared through IS-RPB reactor. • The Fe 3 O 4 nanoparticles showed selective detection of heavy metal ions. • It exhibited favorable sensitivity (14.9 μA μM −1 ) and LOD (0.119 μM) for Pb(II). • The as-prepared nanoparticles showed favorable potential application.

  15. The Fatty Liver Index has limited utility for the detection and quantification of hepatic steatosis in obese patients.

    Science.gov (United States)

    Borman, Meredith A; Ladak, Farah; Crotty, Pam; Pollett, Aaron; Kirsch, Richard; Pomier-Layrargues, Gilles; Beaton, Melanie; Duarte-Rojo, Andres; Elkashab, Magdy; Myers, Robert P

    2013-06-01

    Noninvasive tools for the detection of hepatic steatosis are needed. The Fatty Liver Index (FLI), which includes body mass index (BMI), waist circumference, triglycerides, and γ-glutamyl-transferase, has been proposed as a screening tool for fatty liver. Our objective was to validate the FLI for the detection and quantification of hepatic steatosis in an obese population. Patients with chronic liver disease and BMI ≥ 28 kg/m(2) underwent liver biopsy and FLI determination. FLI performance for diagnosing steatosis compared with biopsy was assessed using areas under receiver operating characteristic curves (AUROCs), and a novel model for the prediction of significant steatosis (≥5 %) was derived. Among 250 included patients, 65 % were male, and the median BMI was 33 kg/m(2); 48 % had nonalcoholic fatty liver disease, and 77 % had significant (≥5 %) steatosis. The FLI was weakly correlated with the percentage (ρ = 0.25, p = 0.0001) and grade of steatosis (ρ = 0.28, p steatosis (91 vs. 80 with steatosis; p = 0.0001) and the AUROC for this outcome was 0.67 (95 % CI 0.59-0.76). At an optimal FLI cut-off of 79, the FLI was 81 % sensitive and 49 % specific, and had positive and negative predictive values of 84 and 43 %, respectively. A novel index including triglycerides, glucose, alkaline phosphatase, and BMI outperformed the FLI for predicting significant steatosis [AUROCs 0.78 vs. 0.68; p = 0.009 (n = 247)]. In obese patients, the FLI is a poor predictor of significant steatosis and has limited utility for steatosis quantification compared with liver histology. A novel index including triglycerides, glucose, alkaline phosphatase, and BMI may be useful, but requires validation.

  16. SERS activity with tenfold detection limit optimization on a type of nanoporous AAO-based complex multilayer substrate

    Science.gov (United States)

    Sui, Chaofan; Wang, Kaige; Wang, Shuang; Ren, Junying; Bai, Xiaohong; Bai, Jintao

    2016-03-01

    Most of SERS applications are constricted by heterogeneous hotspots and aggregates of nanostructure, which result in low sensitivity and poor reproducibility of characteristic signals. This work intends to introduce SERS properties of a type of SERS-active substrate, Au-CuCl2-AAO, which is innovatively developed on a porous anodic alumina oxide (AAO) template. Spectral measuring results of Rhodamine 6G (R6G) on this substrate optimized by controlling morphology and gold thickness showed that enhancement factor (2.30 × 107) and detection limit (10-10 M) were both improved and represented better performance than its template AAO. Homogenous hot spots across the region of interest were achieved by scanning SERS intensity distribution for the band at 1505 cm-1 in 5 × 5 μm2 area. Furthermore, the promising SERS activity of the flower-patterned substrate was theoretically explained through simulation of the electromagnetic field distribution. In addition, this SERS substrate is proposed for applications within the field of chemical and biochemical analyses.Most of SERS applications are constricted by heterogeneous hotspots and aggregates of nanostructure, which result in low sensitivity and poor reproducibility of characteristic signals. This work intends to introduce SERS properties of a type of SERS-active substrate, Au-CuCl2-AAO, which is innovatively developed on a porous anodic alumina oxide (AAO) template. Spectral measuring results of Rhodamine 6G (R6G) on this substrate optimized by controlling morphology and gold thickness showed that enhancement factor (2.30 × 107) and detection limit (10-10 M) were both improved and represented better performance than its template AAO. Homogenous hot spots across the region of interest were achieved by scanning SERS intensity distribution for the band at 1505 cm-1 in 5 × 5 μm2 area. Furthermore, the promising SERS activity of the flower-patterned substrate was theoretically explained through simulation of the

  17. Preparation of sensitive and recyclable porous Ag/TiO{sub 2} composite films for SERS detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhengyi; Yu, Jiajie; Yang, Jingying; Lv, Xiang; Wang, Tianhe, E-mail: thwang56@126.com

    2015-12-30

    Graphical abstract: - Highlights: • A new but simple method of fabricating robust TiO{sub 2} films on glass. • AgNPs were deposited on the surface of TiO{sub 2} films with the assistance of UV irradiation. • Substrates with high SERS sensitivity and excellent recyclability. - Abstract: Porous Ag/TiO{sub 2} composite films were prepared by spin coating of titania on normal glass slides and subsequent photochemical deposition of silver nanoparticles (AgNPs). The films were characterized by XRD and FESEM to reveal micro structural and morphological differences between films obtained under varied conditions. The SERS properties of these films were investigated using aqueous crystal violet (CV) as probe molecules. The results indicate that the content of polyethylene glycol (PEG) and photo-reduction time had significant influences on both the microstructure and SERS performance of Ag/TiO{sub 2} films. The highest SERS sensitivity that allowed as low as 10{sup −10} M aqueous CV to be detected, was achieved with the PEG/(C{sub 4}H{sub 9}O){sub 4}Ti molar ratio being 0.08% and with 30 min of UV irradiation. With this film a linear relationship was established through experiment between SERS intensity and CV concentration from 10{sup −10} to 10{sup −5} M, which could be used as a calibration curve for CV concentration measurement. In addition, the film could be reused as a SERS substrate for up to four times without significantly losing SERS sensitivity if a simple regeneration was followed. It is visualized that the Ag/TiO{sub 2} film on glass has potentials for being developed into a practical SERS substrate with high sensitivity and good reusability.

  18. Multiplex real-time quantitative PCR, microscopy and rapid diagnostic immuno-chromatographic tests for the detection of Plasmodium spp: performance, limit of detection analysis and quality assurance

    Directory of Open Access Journals (Sweden)

    Ralevski Filip

    2009-12-01

    Full Text Available Abstract Background Accurate laboratory diagnosis of malaria species in returning travelers is paramount in the treatment of this potentially fatal infectious disease. Materials and methods A total of 466 blood specimens from returning travelers to Africa, Asia, and South/Central America with suspected malaria infection were collected between 2007 and 2009 at the reference public health laboratory. These specimens were assessed by reference microscopy, multipex real-time quantitative polymerase chain reaction (QPCR, and two rapid diagnostic immuno-chromatographic tests (ICT in a blinded manner. Key clinical laboratory parameters such as limit of detection (LOD analysis on clinical specimens by parasite stage, inter-reader variability of ICTs, staffing implications, quality assurance and cost analysis were evaluated. Results QPCR is the most analytically sensitive method (sensitivity 99.41%, followed by CARESTART (sensitivity 88.24%, and BINAXNOW (sensitivity 86.47% for the diagnosis of malaria in returning travelers when compared to reference microscopy. However, microscopy was unable to specifically identify Plasmodia spp. in 18 out of 170 positive samples by QPCR. Moreover, the 17 samples that were negative by microscopy and positive by QPCR were also positive by ICTs. Quality assurance was achieved for QPCR by exchanging a blinded proficiency panel with another reference laboratory. The Kappa value of inter-reader variability among three readers for BINAXNOW and CARESTART was calculated to be 0.872 and 0.898 respectively. Serial dilution studies demonstrated that the QPCR cycle threshold correlates linearly with parasitemia (R2 = 0.9746 in a clinically relevant dynamic range and retains a LOD of 11 rDNA copies/μl for P. falciparum, which was several log lower than reference microscopy and ICTs. LOD for QPCR is affected not only by parasitemia but the parasite stage distribution of each clinical specimen. QPCR was approximately 6-fold more

  19. Detecting Ebola with limited laboratory access in the Democratic Republic of Congo: evaluation of a clinical passive surveillance reporting system.

    Science.gov (United States)

    Ashbaugh, Hayley R; Kuang, Brandon; Gadoth, Adva; Alfonso, Vivian H; Mukadi, Patrick; Doshi, Reena H; Hoff, Nicole A; Sinai, Cyrus; Mossoko, Mathias; Kebela, Benoit Ilunga; Muyembe, Jean-Jacques; Wemakoy, Emile Okitolonda; Rimoin, Anne W

    2017-09-01

    Ebola virus disease (EVD) can be clinically severe and highly fatal, making surveillance efforts for early disease detection of paramount importance. In areas with limited access to laboratory testing, the Integrated Disease Surveillance and Response (IDSR) strategy in the Democratic Republic of Congo (DRC) may be a vital tool in improving outbreak response. Using DRC IDSR data from the nation's four EVD outbreak periods from 2007-2014, we assessed trends of Viral Hemorrhagic Fever (VHF) and EVD differential diagnoses reportable through IDSR. With official case counts from active surveillance of EVD outbreaks, we assessed accuracy of reporting through the IDSR passive surveillance system. Although the active and passive surveillance represent distinct sets of data, the two were correlated, suggesting that passive surveillance based only on clinical evaluation may be a useful predictor of true cases prior to laboratory confirmation. There were 438 suspect VHF cases reported through the IDSR system and 416 EVD cases officially recorded across the outbreaks examined. Although collected prior to official active surveillance cases, case reporting through the IDSR during the 2007, 2008 and 2012 outbreaks coincided with official EVD epidemic curves. Additionally, all outbreak areas experienced increases in suspected cases for both malaria and typhoid fever during EVD outbreaks, underscoring the importance of training health care workers in recognising EVD differential diagnoses and the potential for co-morbidities. © 2017 John Wiley & Sons Ltd.

  20. Role, limitations and place of medical imaging in the prevention, screening and early detection of breast cancer

    International Nuclear Information System (INIS)

    Lamarque, J.L.; Pujol, J.; Rodiere, M.J.; Laurent, J.C.; Prat, X.; Martin, J.M.; Khodr, A.

    1986-01-01

    For prevention and screening of breast cancer the triad of CLINICAL SIGNS - RADIOLOGY - CYTOLOGY constitutes the most efficient and least costly method. If properly done, clinical examinations can predict the benignity or malignancy of a lesion with an accuracy rate of 80%. While self-examinations are of interest, they cannot replace a proper medical examination. Self-palpation may cause anxiety and cancerophobia both of which may have an as yet poorly understood effect on benign mastopathis. Mammography is currently the most reliable and specific imaging technique. While it can identify stage 0 lesions, it reaches its technical limits in patients with dense breast tissue. It is reserved for high-risk patients. Aspiration cytology is an excellent technique for evaluating areas with a diameter of 1 cm and more. While it cannot diagnose breast cancers in a very early stage, it helps avoid delays in the diagnosis by providing supportive evidence for radiological and clinical findings. Recent pathologic studies showed cancers to develop most often in the presence of proliferative epithelial lesions. This would seem to suggest the need for cytohistologic typing, which can be expected to pick out high-risk patients effectively, to ensure a truly early detection and diagnosis of cancer and to provide for a meaningful prevention. (Author)

  1. Evaluation of the odd-even effect in limits of detection for electron microprobe analysis of natural minerals

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Surendra P., E-mail: spv@cie.unam.mx [Departamento de Sistemas Energeticos, Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Priv. Xochicalco s/no., Col Centro, A.P. 34, Temixco, Mor. 62580 (Mexico); Pandarinath, Kailasa [Departamento de Sistemas Energeticos, Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Priv. Xochicalco s/no., Col Centro, A.P. 34, Temixco, Mor. 62580 (Mexico); Velasco-Tapia, Fernando [Facultad de Ciencias de la Tierra, Universidad Autonoma de Nuevo Leon, Carretera Linares-Cerro Prieto km. 8, Linares, N.L. 67700 (Mexico); Rodriguez-Rios, Rodolfo [Facultad de Ingenieria e Instituto de Geologia, Universidad Autonoma de San Luis Potosi, Av. Dr. Manuel Nava No. 8, Zona Universitaria, San Luis Potosi, S.L.P. 78240 (Mexico)

    2009-04-13

    Limit of detection (LOD), being a fundamental quality parameter for analytical techniques, has been recently investigated and a systematic behavior has been observed for most odd-even element pairs for many techniques. However, to the best of our knowledge very few LOD data are available in published literature for electron microprobe analysis; these consist of three papers, two being on rare-earth elements and the third covering a large number of elements of atomic number between 21 and 92. These data confirm the systematic behavior of LODs for many odd-even pairs. To initiate to full this gap, we determined LODs for several major rock-forming chemical elements from Na to Fe with atomic numbers between 11 and 26, during the microprobe analysis of common minerals (olivine, plagioclase, pyroxene, amphibole, quartz, and opaques) in volcanic rocks. The odd-even effect of nuclear stability seems to be present in LOD data for most odd-even pairs investigated. Nevertheless, the experimental strategy concerning the reference materials, calibration procedure, and blank measurements, should be substantially modified to better evaluate the systematic behavior of LOD values in microprobe analysis.

  2. Evaluation of the odd-even effect in limits of detection for electron microprobe analysis of natural minerals

    International Nuclear Information System (INIS)

    Verma, Surendra P.; Pandarinath, Kailasa; Velasco-Tapia, Fernando; Rodriguez-Rios, Rodolfo

    2009-01-01

    Limit of detection (LOD), being a fundamental quality parameter for analytical techniques, has been recently investigated and a systematic behavior has been observed for most odd-even element pairs for many techniques. However, to the best of our knowledge very few LOD data are available in published literature for electron microprobe analysis; these consist of three papers, two being on rare-earth elements and the third covering a large number of elements of atomic number between 21 and 92. These data confirm the systematic behavior of LODs for many odd-even pairs. To initiate to full this gap, we determined LODs for several major rock-forming chemical elements from Na to Fe with atomic numbers between 11 and 26, during the microprobe analysis of common minerals (olivine, plagioclase, pyroxene, amphibole, quartz, and opaques) in volcanic rocks. The odd-even effect of nuclear stability seems to be present in LOD data for most odd-even pairs investigated. Nevertheless, the experimental strategy concerning the reference materials, calibration procedure, and blank measurements, should be substantially modified to better evaluate the systematic behavior of LOD values in microprobe analysis.

  3. Morpholinoethanesulfonic acid-based buffer system for improved detection limit and stability of the fluoride ion selective electrode

    International Nuclear Information System (INIS)

    Fouskaki, M.; Sotiropoulou, S.; Koci, M.; Chaniotakis, N.A.

    2002-01-01

    The zwitterionic morpholinoethanesulfonic acid (MES) is used as the basis for the development of a new total ionic strength adjustor buffer system for improving the analytical characteristics of fluoride sensor. Impedance analysis, atomic force microscopy (AFM) and dissolution studies of the LaF 3 crystal, together with the potential stability and sensor sensitivity over time have aided in the elucidation of the processes that take place at the surface of the LaF 3 crystal, that seem to determine the sensor behaviour. Even though AFM analysis shows that both buffers used (MES or acetate) cause a similar increase in surface roughness, the data from the other studies suggest that in the first case there is a reversible ion exchange process at the interface, while in the second case this process is irreversible, leading to fast poisoning of the crystal surface. The use of 0.5 M MES and NaCl buffer adjusted to pH 5.50 allows for the continuous operation of the sensor under flow injection analysis conditions for at least 5 days with sensitivity of 60 mV per decade [F - ], detection limit of 2.1x10 -7 M [F - ] and fast response time

  4. Preparation of Microcellular Epoxy Foams through a Limited-Foaming Process: A Contradiction with the Time-Temperature-Transformation Cure Diagram.

    Science.gov (United States)

    Wang, Lijun; Zhang, Chun; Gong, Wei; Ji, Yubi; Qin, Shuhao; He, Li

    2018-01-01

    3D cross-linking networks are generated through chemical reactions between thermosetting epoxy resin and hardener during curing. The curing degree of epoxy material can be increased by increasing curing temperature and/or time. The epoxy material must then be fully cured through a postcuring process to optimize its material characteristics. Here, a limited-foaming method is introduced for the preparation of microcellular epoxy foams (Lim-foams) with improved cell morphology, high thermal expansion coefficient, and good compressive properties. Lim-foams exhibit a lower glass transition temperature (T g ) and curing degree than epoxy foams fabricated through free-foaming process (Fre-foams). Surprisingly, however, the T g of Lim-foams is unaffected by postcuring temperature and time. This phenomenon, which is related to high gas pressure in the bubbles, contradicts that indicated by the time-temperature-transformation cure diagram. High bubble pressure promotes the movement of molecular chains under heating at low temperature and simultaneously suppresses the etherification cross-linking reaction during post-curing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Subcritical water extraction combined with molecular imprinting technology for sample preparation in the detection of triazine herbicides.

    Science.gov (United States)

    Zhao, Fengnian; Wang, Shanshan; She, Yongxin; Zhang, Chao; Zheng, Lufei; Jin, Maojun; Shao, Hua; Jin, Fen; Du, Xinwei; Wang, Jing

    2017-09-15

    A selective, environmentally friendly, and cost-effective sample extraction method based on a combination of subcritical water extraction (SWE) and molecularly imprinted solid-phase extraction (MISPE) was developed for the determination of eight triazine herbicides in soil samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In SWE, the highest extraction yields of triazine herbicides were obtained under 150°C for 15min using 20% ethanol as the organic modifier. Addition of MIP during SWE increased the extraction efficiency, and using MIP as a selective SPE sorbent improved the enrichment capability. Soil samples were treated with the optimized extraction MIP/SWE-MISPE method and analyzed by LC-MS/MS. The novel technique was then applied to soil samples for the determination of triazine herbicides, and better recoveries (78.9%-101%) were obtained compared with using SWE-MISPE (30%-67%). Moreover, this newly developed method displayed good linearity (R 2 >0.99) and precision (2.7-9.8%), and low enough detection limits (0.4-3.3μgkg -1 ). This combination of SWE and MIP technology is a simple, effective and promising method to selectively extract class-specific compounds in complex samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Limited diagnostic accuracy of magnetic resonance imaging and clinical tests for detecting partial-thickness tears of the rotator cuff.

    Science.gov (United States)

    Brockmeyer, Matthias; Schmitt, Cornelia; Haupert, Alexander; Kohn, Dieter; Lorbach, Olaf

    2017-12-01

    The reliable diagnosis of partial-thickness tears of the rotator cuff is still elusive in clinical practise. Therefore, the purpose of the study was to determine the diagnostic accuracy of MR imaging and clinical tests for detecting partial-thickness tears of the rotator cuff as well as the combination of these parameters. 334 consecutive shoulder arthroscopies for rotator cuff pathologies performed during the time period between 2010 and 2012 were analyzed retrospectively for the findings of common clinical signs for rotator cuff lesions and preoperative MR imaging. These were compared with the intraoperative arthroscopic findings as "gold standard". The reports of the MR imaging were evaluated with regard to the integrity of the rotator cuff. The Ellman Classification was used to define partial-thickness tears of the rotator cuff in accordance with the arthroscopic findings. Descriptive statistics, sensitivity, specificity, positive and negative predictive value were calculated. MR imaging showed 80 partial-thickness and 70 full-thickness tears of the rotator cuff. The arthroscopic examination confirmed 64 partial-thickness tears of which 52 needed debridement or refixation of the rotator cuff. Sensitivity for MR imaging to identify partial-thickness tears was 51.6%, specificity 77.2%, positive predictive value 41.3% and negative predictive value 83.7%. For the Jobe-test, sensitivity was 64.1%, specificity 43.2%, positive predictive value 25.9% and negative predictive value 79.5%. Sensitivity for the Impingement-sign was 76.7%, specificity 46.6%, positive predictive value 30.8% and negative predictive value 86.5%. For the combination of MR imaging, Jobe-test and Impingement-sign sensitivity was 46.9%, specificity 85.4%, positive predictive value 50% and negative predictive value 83.8%. The diagnostic accuracy of MR imaging and clinical tests (Jobe-test and Impingement-sign) alone is limited for detecting partial-thickness tears of the rotator cuff. Additionally

  7. Multivariate estimation of the limit of detection by orthogonal partial least squares in temperature-modulated MOX sensors.

    Science.gov (United States)

    Burgués, Javier; Marco, Santiago

    2018-08-17

    Metal oxide semiconductor (MOX) sensors are usually temperature-modulated and calibrated with multivariate models such as partial least squares (PLS) to increase the inherent low selectivity of this technology. The multivariate sensor response patterns exhibit heteroscedastic and correlated noise, which suggests that maximum likelihood methods should outperform PLS. One contribution of this paper is the comparison between PLS and maximum likelihood principal components regression (MLPCR) in MOX sensors. PLS is often criticized by the lack of interpretability when the model complexity increases beyond the chemical rank of the problem. This happens in MOX sensors due to cross-sensitivities to interferences, such as temperature or humidity and non-linearity. Additionally, the estimation of fundamental figures of merit, such as the limit of detection (LOD), is still not standardized in multivariate models. Orthogonalization methods, such as orthogonal projection to latent structures (O-PLS), have been successfully applied in other fields to reduce the complexity of PLS models. In this work, we propose a LOD estimation method based on applying the well-accepted univariate LOD formulas to the scores of the first component of an orthogonal PLS model. The resulting LOD is compared to the multivariate LOD range derived from error-propagation. The methodology is applied to data extracted from temperature-modulated MOX sensors (FIS SB-500-12 and Figaro TGS 3870-A04), aiming at the detection of low concentrations of carbon monoxide in the presence of uncontrolled humidity (chemical noise). We found that PLS models were simpler and more accurate than MLPCR models. Average LOD values of 0.79 ppm (FIS) and 1.06 ppm (Figaro) were found using the approach described in this paper. These values were contained within the LOD ranges obtained with the error-propagation approach. The mean LOD increased to 1.13 ppm (FIS) and 1.59 ppm (Figaro) when considering validation samples

  8. Detection of Cucurbit chlorotic yellows virus from Bemisia tabaci captured on sticky traps using reverse transcription loop-mediated isothermal amplification (RT-LAMP) and simple template preparation.

    Science.gov (United States)

    Okuda, Mitsuru; Okuda, Shiori; Iwai, Hisashi

    2015-09-01

    Cucurbit chlorotic yellows virus (CCYV) of the genus Crinivirus within the family Closteroviridae is an emerging infectious agent of cucurbits leading to severe disease and significant economic losses. Effective detection and identification methods for this virus are urgently required. In this study, a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed to detect CCYV from its vector Bemisia tabaci. LAMP primer sets to detect CCYV were evaluated for their sensitivity and specificity, and a primer set designed from the HSP70h gene with corresponding loop primers were selected. The RT-LAMP assay was applied to detect CCYV from viruliferous B. tabaci trapped on sticky traps. A simple extraction procedure using RNAsecure™ was developed for template preparation. CCYV was detected in all of the B. tabaci 0, 1, 7 and 14 days after they were trapped. Although the rise of turbidity was delayed in reactions using RNA from B. tabaci trapped for 7 and 14 days compared with those from 0 and 1 day, the DNA amplification was sufficient to detect CCYV in all of the samples. These findings therefore present a simple template preparation method and an effective RT-LAMP assay, which can be easily and rapidly performed to monitor CCYV-viruliferous B. tabaci in the field. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Methodology applied by the Petroleum, Natural Gas and Bio fuels National Agency for detection of cartels - their limits and perspectives; Metodology adotada pela Agencia Nacional do Petroleo, Gas Natural e Biocombustiveis para detectecao de carteis - seus limites e perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Pedra, Douglas Pereira; Sales, Orlando de Araujo Vilela; Baran, Patricia Huguenin; Paiva, Rodrigo Milao de [Agencia Nacional do Petroleo, Gas Natural e Biocombustiveis (ANP), Rio de Janeiro, RJ (Brazil). Regulacao de Petroleo, seus Derivados, Alcool Combustivel e Gas Natural; Bicalho, Lucia Maria de Oliveira Navegantes [Universidade Federal do Rio de Janeiro (PPE/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Planejamento Energetico

    2010-07-01

    This paper presents the present methodology used by the Defense Competition Coordination of the Petroleum National Agency for detection of vestiges of cartels in the Brazilian fuel market, their limits, in view of the instruments presently at the disposal of the Agency and perspectives of modification from the eventual availability of new instruments.

  10. Interaction of cosmic ray muons with spent nuclear fuel dry casks and determination of lower detection limit

    Energy Technology Data Exchange (ETDEWEB)

    Chatzidakis, S., E-mail: schatzid@purdue.edu; Choi, C.K.; Tsoukalas, L.H.

    2016-08-21

    The potential non-proliferation monitoring of spent nuclear fuel sealed in dry casks interacting continuously with the naturally generated cosmic ray muons is investigated. Treatments on the muon RMS scattering angle by Moliere, Rossi-Greisen, Highland and, Lynch-Dahl were analyzed and compared with simplified Monte Carlo simulations. The Lynch-Dahl expression has the lowest error and appears to be appropriate when performing conceptual calculations for high-Z, thick targets such as dry casks. The GEANT4 Monte Carlo code was used to simulate dry casks with various fuel loadings and scattering variance estimates for each case were obtained. The scattering variance estimation was shown to be unbiased and using Chebyshev's inequality, it was found that 10{sup 6} muons will provide estimates of the scattering variances that are within 1% of the true value at a 99% confidence level. These estimates were used as reference values to calculate scattering distributions and evaluate the asymptotic behavior for small variations on fuel loading. It is shown that the scattering distributions between a fully loaded dry cask and one with a fuel assembly missing initially overlap significantly but their distance eventually increases with increasing number of muons. One missing fuel assembly can be distinguished from a fully loaded cask with a small overlapping between the distributions which is the case of 100,000 muons. This indicates that the removal of a standard fuel assembly can be identified using muons providing that enough muons are collected. A Bayesian algorithm was developed to classify dry casks and provide a decision rule that minimizes the risk of making an incorrect decision. The algorithm performance was evaluated and the lower detection limit was determined.

  11. Application and Limitations of GPS Radio Occultation (GPS-RO) Data for Atmospheric Boundary Layer Height Detection over the Arctic.

    Science.gov (United States)

    Ganeshan, M.; Wu, D. L.

    2014-12-01

    Due to recent changes in the Arctic environment, it is important to monitor the atmospheric boundary layer (ABL) properties over the Arctic Ocean, especially to explore the variability in ABL clouds (such as sensitivity and feedback to sea ice loss). For example, radiosonde and satellite observations of the Arctic ABL height (and low-cloud cover) have recently suggested a positive response to sea ice loss during October that may not occur during the melt season (June-September). Owing to its high vertical and spatiotemporal resolution, an independent ABL height detection algorithm using GPS Radio Occultation (GPS-RO) refractivity in the Arctic is explored. Similar GPS-RO algorithms developed previously typically define the level of the most negative moisture gradient as the ABL height. This definition is favorable for subtropical oceans where a stratocumulus-topped ABL is often capped by a layer of sharp moisture lapse rate (coincident with the temperature inversion). The Arctic Ocean is also characterized by stratocumulus cloud cover, however, the specific humidity does not frequently decrease in the ABL capping inversion. The use of GPS-RO refractivity for ABL height retrieval therefore becomes more complex. During winter months (December-February), when the total precipitable water in the troposphere is a minimum, a fairly straightforward algorithm for ABL height retrieval is developed. The applicability and limitations of this method for other seasons (Spring, Summer, Fall) is determined. The seasonal, interannual and spatial variability in the GPS-derived ABL height over the Arctic Ocean, as well as its relation to the underlying surface (ice vs. water), is investigated. The GPS-RO profiles are also explored for the evidence of low-level moisture transport in the cold Arctic environment.

  12. Preparation and bioevaluation of 99Tcm-HYNIC-Annexin B1 as a novel radiotracer for apoptosis detection

    International Nuclear Information System (INIS)

    Luo Quanyong; Luo Qiong; Lu Hankui; Zhu Ruisen; Wang Fang; Zhang Yi; Sun Shuhan; Zhang Zhiyong; Liu Xingfeng

    2008-01-01

    Objective: Annexin B1, a novel Ca 2+ -dependent phosphatidylserine (PS)-binding protein, has been shown to have a high affinity for PS exposed on the surface of apoptotic cells or activated platelets. The aim of this study was to develop and bioevaluate an Annexin B1 based PS-targeting radiotracer labeled with 99 Tc m . Methods: Annexin B1 was indirectly labeled with 99 Tc m using hydrazinonicotinamide (HYNIC) as a bifunctional chelator agent. Binding assay with human activated platelets was used to evaluate the biological activity of 99 Tc m -HYNIC-Annexin B1 in vitro. The potential of 99 Tc m -HYNIC-Annexin B1 to detect apoptosis in vivo was evaluated in mice models with dexamethasone-inducecd thymus apoptosis and anti-Fas antibody induced liver apoptosis. The paired t-test was used to analyse the data. Results: The labeling procedure yielded a compound with radiochemical purity higher than 96% and good in vitro stability. Plate- lets binding assay indicated that 99 Tc m -HYNIC-Annexin B1 retained their PS binding activity in vitro. The percentage activity of injection dose per gram of tissue (% ID/g) of mouse thymus showed a 3.50-fold increase at 18 h after administration of dexamethasone compared with control mice (t=5.234, P 99 Tc m -HYNIC-Annexin B1 in the liver of anti-Fas antibody treated mice. The %ID/g of apoptotic murine liver showed a 2.02-fo1d increase at 2 h after the administration of anti-Fas antibody compared with control mice (t=6.178, P 99 Tc m -HYNIC-Annexin B1 can be prepared with high radiochemical purity and in vitro stability. These da- ta also suggest that 99 Tc m -HYNIC-Annexin B1 retains its in vitro and in vivo biological activities. It may therefore be useful as a novel radioligand for the noninvasive imaging of PS externalization associated with apoptosis. (authors)

  13. Efficient electrocatalytic reduction and detection of hydrogen peroxide at an IrIVOx·H2O nanostructured electrode prepared by electroflocculation

    International Nuclear Information System (INIS)

    Liu, Pei-Yin; Sun, Sin-Cih; Chen, Yi-Shiang; Chuang, Min-Chieh

    2016-01-01

    An Ir IV Ox·nH 2 O nanostructured electrode prepared by electroflocculation is reported; the electrode efficiently catalyzes the electrochemical reduction of hydrogen peroxide (H 2 O 2 ). Linear sweep voltammograms reveal that the potential onset arising due to the reduction of H 2 O 2 (1 mM) occurs at -0.1 V (vs. Ag/AgCl), which is more anodic than the onset potential occurring on the glassy carbon electrode by 400 mV, thereby substantiating the catalytic utility of Ir IV Ox·nH 2 O. The number of electrons transferred in the process, estimated via the Koutecky-Levich equation, is 1.89 ± 0.30. The Tafel slope obtained from polarization measurements is ca. 240.9 mV/dec. Furthermore, the Ir IV Ox·nH 2 O nanostructured electrode exhibits response with linear relationship against H 2 O 2 concentrations ranging over 0-1 mM (when agitated) and 0-150 μM (in flow injection analysis); the limit of detection (3σ), as determined under flow injection analysis, is 5 μM. The as-fabricated electrode is insensitive to the oxidation of ascorbic acid (0.1 mM) and acetaminophen (0.1 mM) and exhibits stable amperometric response (over twenty successive trials), albeit a slight drift in the sensor response is observed during the initial six evaluations. Based on the results, the electrocatalytic mechanism involving the following steps is proposed: (1) the reduction of Ir from Ir IV to Ir III , (2) catalytic cleavage of the O-O bond to generate OH· radicals, and (3) the reduction of the OH· radicals to OH − via the reoxidation of Ir III to Ir IV .

  14. A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples

    DEFF Research Database (Denmark)

    Sun, Yi; Than Linh, Quyen; Hung, Tran Quang

    2015-01-01

    was capable to detect Salmonella at concentration of 50 cells per test within 40 min. The simple design, together with high level of integration, isothermal amplification, and quantitative analysis of multiple samples in short time will greatly enhance the practical applicability of the LOC system for rapid...... amplification (LAMP) for rapid and quantitative detection of Salmonella spp. in food samples. The whole diagnostic procedures including DNA isolation, isothermal amplification, and real-time detection were accomplished in a single chamber. Up to eight samples could be handled simultaneously and the system...... and usually take a few hours to days to complete. In response to the demand for rapid on line or at site detection of pathogens, in this study, we describe for the first time an eight-chamber lab-on-a-chip (LOC) system with integrated magnetic beads-based sample preparation and loop-mediated isothermal...

  15. Eco-friendly plasmonic sensors: using the photothermal effect to prepare metal nanoparticle-containing test papers for highly sensitive colorimetric detection.

    Science.gov (United States)

    Tseng, Shao-Chin; Yu, Chen-Chieh; Wan, Dehui; Chen, Hsuen-Li; Wang, Lon Alex; Wu, Ming-Chung; Su, Wei-Fang; Han, Hsieh-Cheng; Chen, Li-Chyong

    2012-06-05

    Convenient, rapid, and accurate detection of chemical and biomolecules would be a great benefit to medical, pharmaceutical, and environmental sciences. Many chemical and biosensors based on metal nanoparticles (NPs) have been developed. However, as a result of the inconvenience and complexity of most of the current preparation techniques, surface plasmon-based test papers are not as common as, for example, litmus paper, which finds daily use. In this paper, we propose a convenient and practical technique, based on the photothermal effect, to fabricate the plasmonic test paper. This technique is superior to other reported methods for its rapid fabrication time (a few seconds), large-area throughput, selectivity in the positioning of the NPs, and the capability of preparing NP arrays in high density on various paper substrates. In addition to their low cost, portability, flexibility, and biodegradability, plasmonic test paper can be burned after detecting contagious biomolecules, making them safe and eco-friendly.

  16. PREPARATIVE ISOLATION AND PURIFICATION OF THREE GLYCINE-CONJUGATED CHOLIC ACIDS FROM PULVIS FELLIS SUIS BY HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY COUPLED WITH ELSD DETECTION

    OpenAIRE

    He, Jiao; Li, Jing; Sun, Wenji; Zhang, Tianyou; Ito, Yoichiro

    2012-01-01

    Coupled with evaporative light scattering detection, a high-speed counter-current chromatography (HSCCC) method was developed for preparative isolation and purification of three glycine-conjugated cholic acids, glycochenodeoxycholic acid (GCDCA), glycohyodeoxycholic acid (GHDCA) and glycohyocholic acid (GHCA) from Pulvis Fellis Suis (Pig gallbladder bile) for the first time. The separation was performed with a two-phase solvent system consisted of chloroform-methanol-water-acetic acid (65:30:...

  17. Method to Solve the Problem of the Radioactivity Detection in Environmental Samples. Characteristic Limits; Metodos para la Resolucion del Problema de la Detecfcion de Radiactividad en Muestras Ambientales. Limites Caracteristicos

    Energy Technology Data Exchange (ETDEWEB)

    Gasco, C.; Martinez, M.; Heras, M.

    2009-07-21

    The problem of the detection or when the radioactivity can be considered as higher than the background using different measurement techniques has been the objective of several statistical studies and controversies. The detection limit and the critical limit were studied by Currie in year 1968 and used by radiochemistry laboratories considering different ways of calculation that introduced confusion and not correct implementations. In the last few years, and due to the increasing number of standardization processes on the field of radioactivity and accreditation, several international institutions have chosen to unify the criteria for using common determination of detection limits. The most used methods are those developed by MARLAP and International Standard Organization ISO (Standard-11929). In this report are summarised both standards doing a comparative study and giving some examples of how to apply these limits. In same cases, little differences in the uncertainty calculation have been observed but the final results have been concordant. A deeply study of these standards can be done consulting the web page of the American Labs that developed MARLAP or buying the original ISO standard ISO-11929 recently approved (2009). (Author) 17 refs.

  18. Methane Flux Estimation from Point Sources using GOSAT Target Observation: Detection Limit and Improvements with Next Generation Instruments

    Science.gov (United States)

    Kuze, A.; Suto, H.; Kataoka, F.; Shiomi, K.; Kondo, Y.; Crisp, D.; Butz, A.

    2017-12-01

    Atmospheric methane (CH4) has an important role in global radiative forcing of climate but its emission estimates have larger uncertainties than carbon dioxide (CO2). The area of anthropogenic emission sources is usually much smaller than 100 km2. The Thermal And Near infrared Sensor for carbon Observation Fourier-Transform Spectrometer (TANSO-FTS) onboard the Greenhouse gases Observing SATellite (GOSAT) has measured CO2 and CH4 column density using sun light reflected from the earth's surface. It has an agile pointing system and its footprint can cover 87-km2 with a single detector. By specifying pointing angles and observation time for every orbit, TANSO-FTS can target various CH4 point sources together with reference points every 3 day over years. We selected a reference point that represents CH4 background density before or after targeting a point source. By combining satellite-measured enhancement of the CH4 column density and surface measured wind data or estimates from the Weather Research and Forecasting (WRF) model, we estimated CH4emission amounts. Here, we picked up two sites in the US West Coast, where clear sky frequency is high and a series of data are available. The natural gas leak at Aliso Canyon showed a large enhancement and its decrease with time since the initial blowout. We present time series of flux estimation assuming the source is single point without influx. The observation of the cattle feedlot in Chino, California has weather station within the TANSO-FTS footprint. The wind speed is monitored continuously and the wind direction is stable at the time of GOSAT overpass. The large TANSO-FTS footprint and strong wind decreases enhancement below noise level. Weak wind shows enhancements in CH4, but the velocity data have large uncertainties. We show the detection limit of single samples and how to reduce uncertainty using time series of satellite data. We will propose that the next generation instruments for accurate anthropogenic CO2 and CH

  19. Comparison of detection limits in environmental analysis--is it possible? An approach on quality assurance in the lower working range by verification.

    Science.gov (United States)

    Geiss, S; Einax, J W

    2001-07-01

    Detection limit, reporting limit and limit of quantitation are analytical parameters which describe the power of analytical methods. These parameters are used for internal quality assurance and externally for competing, especially in the case of trace analysis in environmental compartments. The wide variety of possibilities for computing or obtaining these measures in literature and in legislative rules makes any comparison difficult. Additionally, a host of terms have been used within the analytical community to describe detection and quantitation capabilities. Without trying to create an order for the variety of terms, this paper is aimed at providing a practical proposal for answering the main questions for the analysts concerning quality measures above. These main questions and related parameters were explained and graphically demonstrated. Estimation and verification of these parameters are the two steps to get real measures. A rule for a practical verification is given in a table, where the analyst can read out what to measure, what to estimate and which criteria have to be fulfilled. In this manner verified parameters detection limit, reporting limit and limit of quantitation now are comparable and the analyst himself is responsible to the unambiguity and reliability of these measures.

  20. Optimizing detectability

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    HPLC is useful for trace and ultratrace analyses of a variety of compounds. For most applications, HPLC is useful for determinations in the nanogram-to-microgram range; however, detection limits of a picogram or less have been demonstrated in certain cases. These determinations require state-of-the-art capability; several examples of such determinations are provided in this chapter. As mentioned before, to detect and/or analyze low quantities of a given analyte at submicrogram or ultratrace levels, it is necessary to optimize the whole separation system, including the quantity and type of sample, sample preparation, HPLC equipment, chromatographic conditions (including column), choice of detector, and quantitation techniques. A limited discussion is provided here for optimization based on theoretical considerations, chromatographic conditions, detector selection, and miscellaneous approaches to detectability optimization. 59 refs

  1. A fluorescence probe based on the nitrogen-doped carbon dots prepared from orange juice for detecting Hg2+ in water

    International Nuclear Information System (INIS)

    Li, Zhili; Zhang, Ying; Niu, Qianqian; Mou, Mingyao; Wu, Yi; Liu, Xiaoxuan; Yan, Zhengyu; Liao, Shenghua

    2017-01-01

    An excellent biocompatible nitrogen-doped carbon dots (N-CDs) was successfully synthesized from orange juice and ethylenediamine by hydrothermal decomposition method. The as-prepared N-CDs were mono-dispersed spherical nanoparticles with a narrow size distribution of 0.5–3.0 nm and showed a good dispersion and stability in aqueous solution with the pH value ranging from 3.0 to 13.0. Photoluminescence spectra of as-prepared N-CDs demonstrated that the fluorescence intensity of N-CDs was increased with the doped nitrogen atoms and the FL-QY (fluorescence quantum yield) of N-CDs was up to 31.7%. Compared with Gly-CQDs(CQDs synthesied by Gly), which were prepared from chemical carbon source via hydrothermal decomposition method, the as-prepared N-CDs showed much lower cytotoxicity for Human THP-1 macrophage cells. These results indicated N-CDs prepared by our proposed method have excellent compatibility and more suitable for the application in biolabeling and bioimage. Due to the fluorescence quenching of N-CDs by mercury (II) ion (Hg 2+ ), a sensitive and selective method was developed for detecting Hg 2+ . The results indicated that the fluorescence intensity ratio of N-CDs was proportional to the concentration of Hg 2+ in the range from 4.0 μg/mL to 32.0 μg/mL and the recovery of spiked samples was ranged from 102.0% to 103.0%, which hinted our proposed method has a good sensitivity and accuracy and was suitable for detecting Hg 2+ with satisfactory in tap water.

  2. Partial Least Squares Calibration Modeling Towards the Multivariate Limit of Detection for Enriched Isotopic Mixtures via Laser Ablation Molecular Isotopic Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Candace [Florida Agriculture & Mechanic Univ.; Profeta, Luisa [Alakai Defense Systems, Inc.; Akpovo, Codjo [Florida Agriculture & Mechanic Univ.; Stowe, Ashley [Y-12 National Security Complex, Oak Ridge, TN (United States); Johnson, Lewis [Florida Agriculture & Mechanic Univ.

    2017-10-09

    The psuedo univariate limit of detection was calculated to compare to the multivariate interval. ompared with results from the psuedounivariate LOD, the multivariate LOD includes other factors (i.e. signal uncertainties) and the reveals the significance in creating models that not only use the analyte’s emission line but also its entire molecular spectra.

  3. A need for standardization in drinking water analysis – an investigation of DNA extraction procedure, primer choice and detection limit of 16S rRNA amplicon sequencing

    DEFF Research Database (Denmark)

    Brandt, Jakob; Nielsen, Per Halkjær; Albertsen, Mads

    have been made to illuminate the effects specifically related to bacterial communities in drinking water. In this study, we investigated the impact of the DNA extraction and primer choice on the observed community structure, and we also estimated the detection limit of the 16S rRNA amplicon sequencing...

  4. Photoinduced triplet-state electron transfer of platinum porphyrin: a one-step direct method for sensing iodide with an unprecedented detection limit

    KAUST Repository

    Masih, Dilshad; Aly, Shawkat Mohammede; Alarousu, Erkki; Mohammed, Omar F.

    2015-01-01

    previously unattained detection limit of 1 × 10−12 M) and economical method for the determination of iodide. To fully understand the reaction mechanism responsible for the phosphorescence quenching process, we have employed cutting-edge time-resolved laser

  5. Detection limits for close eclipsing and transiting sub-stellar and planetary companions to white dwarfs in the WASP survey

    OpenAIRE

    Faedi, F.; West, R. G.; Burleigh, M. R.; Goad, M. R.; Hebb, L.

    2010-01-01

    We have performed extensive simulations to explore the possibility of detecting eclipses and transits of close, sub-stellar and planetary companions to white dwarfs in WASP light-curves. Our simulations cover companions $\\sim0.3\\Re

  6. Limited diagnostic capacities of two commercial assays for the detection of Leptospira immunoglobulin M antibodies in Laos

    NARCIS (Netherlands)

    Blacksell, Stuart D.; Smythe, Lee; Phetsouvanh, Rattanaphone; Dohnt, Michael; Hartskeerl, Rudy; SymondS, Meegan; Slack, Andrew; Vongsouvath, Manivanh; Davong, Viengmone; Lattana, Olay; Phongmany, Simmaly; Keolouangkot, Valy; White, Nicholas J.; Day, Nicholas P. J.; Newton, Paul N.

    2006-01-01

    The diagnostic utility of immunochromatographic (Leptotek) and enzyme-linked immunosorbent assay (ELISA; Panbio) tests for the detection of Leptospira immunoglobulin M antibodies was assessed in febrile adults admitted in Vientiane, Laos. Both tests demonstrated poor diagnostic accuracy using

  7. Detection of Salmonella enterica in Meat in Less than 5 Hours by a Low-Cost and Noncomplex Sample Preparation Method.

    Science.gov (United States)

    Fachmann, M S R; Löfström, C; Hoorfar, J; Hansen, F; Christensen, J; Mansdal, S; Josefsen, M H

    2017-03-01

    Salmonella is recognized as one of the most important foodborne bacteria and has wide health and socioeconomic impacts worldwide. Fresh pork meat is one of the main sources of Salmonella , and efficient and fast methods for detection are therefore necessary. Current methods for Salmonella detection in fresh meat usually include >16 h of culture enrichment, in a few cases IMPORTANCE While the cost of analysis and hands-on time of the presented rapid method were comparable to those of reference culture methods, the fast product release by this method can provide the meat industry with a competitive advantage. Not only will the abattoirs save costs for work hours and cold storage, but consumers and retailers will also benefit from fresher meat with a longer shelf life. Furthermore, the presented sample preparation might be adjusted for application in the detection of other pathogenic bacteria in different sample types. Copyright © 2017 American Society for Microbiology.

  8. Installation of high-resolution ERDA in UTTAC at the University of Tsukuba: Determination of the energy resolution and the detection limit for hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Sekiba, D., E-mail: sekiba@tac.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8573 (Japan); University of Tsukuba, Tandem Accelerator Complex (UTTAC), Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577 (Japan); Chito, K.; Harayama, I. [Institute of Applied Physics, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8573 (Japan); Watahiki, Y.; Ishii, S. [University of Tsukuba, Tandem Accelerator Complex (UTTAC), Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577 (Japan); Ozeki, K. [Department of Mechanical Engineering, Ibaraki University, Nakanarusawa 4-12-1, Hitachi, Ibaraki 316-8511 (Japan)

    2017-06-15

    A newly developed high-resolution elastic recoil detection analysis (HERDA) system installed at the 1 MV Tandetron in UTTAC at the University of Tsukuba is introduced. The effective solid angle of detector, energy resolution and detection limit for hydrogen are, for the first time, determined quantitatively by the measurements on an a-C:H (and D) film deposited on a Si substrate. In the case of a 500 keV {sup 16}O{sup +} as the incident beam, an energy resolution of ∼0.45 keV and a detection limit of ∼3.8 × 10{sup 20} atoms/cm{sup 3} (∼0.18 at.%) with a data acquisition time of ∼310 s are derived.

  9. Limited copy number-high resolution melting (LCN-HRM) enables the detection and identification by sequencing of low level mutations in cancer biopsies.

    Science.gov (United States)

    Do, Hongdo; Dobrovic, Alexander

    2009-10-08

    Mutation detection in clinical tumour samples is challenging when the proportion of tumour cells, and thus mutant alleles, is low. The limited sensitivity of conventional sequencing necessitates the adoption of more sensitive approaches. High resolution melting (HRM) is more sensitive than sequencing but identification of the mutation is desirable, particularly when it is important to discriminate false positives due to PCR errors or template degradation from true mutations.We thus developed limited copy number - high resolution melting (LCN-HRM) which applies limiting dilution to HRM. Multiple replicate reactions with a limited number of target sequences per reaction allow low level mutations to be detected. The dilutions used (based on Ct values) are chosen such that mutations, if present, can be detected by the direct sequencing of amplicons with aberrant melting patterns. Using cell lines heterozygous for mutations, we found that the mutations were not readily detected when they comprised 10% of total alleles (20% tumour cells) by sequencing, whereas they were readily detectable at 5% total alleles by standard HRM. LCN-HRM allowed these mutations to be identified by direct sequencing of those positive reactions.LCN-HRM was then used to review formalin-fixed paraffin-embedded (FFPE) clinical samples showing discordant findings between sequencing and HRM for KRAS exon 2 and EGFR exons 19 and 21. Both true mutations present at low levels and sequence changes due to artefacts were detected by LCN-HRM. The use of high fidelity polymerases showed that the majority of the artefacts were derived from the damaged template rather than replication errors during amplification. LCN-HRM bridges the sensitivity gap between HRM and sequencing and is effective in distinguishing between artefacts and true mutations.

  10. Detection of hormonal anabolic compounds in calf urine and unverified growth-promoting preparations : application of the AR-LUX bioassay for screening and determination of androgenic activity

    NARCIS (Netherlands)

    Blankvoort, B.M.G.; Aarts, J.M.M.J.G.; Schilt, R.; Geerdink, P.; Spenkelink, B.; Rodenburg, R.J.T.

    2003-01-01

    Despite a ban by the European Union, the use of anabolic steroids and repartitioning agents in cattle is still occasionally observed. Due to continuing improvements in analytical techniques, very low detection limits for individual compounds have been achieved. In response to these developments,

  11. Detection of hormonal anabolic compounds in calf urine and unverified growth-promoting preparations: application of the AR-LUX bioassay for screening and determination of androgenic activity

    NARCIS (Netherlands)

    Blankvoort, B.M.G.; Aarts, J.M.M.J.G.; Schilt, R.; Geerdink, P.; Spenkelink, A.; Rodenburg, R.J.T.

    2003-01-01

    Despite a ban by the European Union, the use of anabolic steroids and repartitioning agents in cattle is still occasionally observed. Due to continuing improvements in analytical techniques, very low detection limits for individual compounds have been achieved. In response to these developments,

  12. Detection of nanoplastics in food by asymmetric flow field-flow fractionation coupled to multi-angle light scattering: possibilities, challenges and analytical limitations

    DEFF Research Database (Denmark)

    Correia, Manuel; Löschner, Katrin

    2018-01-01

    We tested the suitability of asymmetric flow field-flow fractionation (AF4) coupled to multi-angle light scattering (MALS) for detection of nanoplastics in fish. A homogenized fish sample was spiked with 100 nm polystyrene nanoparticles (PSNPs) (1.3 mg/g fish). Two sample preparation strategies...... were tested: acid digestion and enzymatic digestion with proteinase K. Both procedures were found suitable for degradation of the organic matrix. However, acid digestion resulted in large PSNPs aggregates/agglomerates (> 1 μm). The presence of large particulates was not observed after enzymatic...

  13. Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer.

    Science.gov (United States)

    Nardi, Giacomo; Manet, Ilse; Monti, Sandra; Miranda, Miguel A; Lhiaubet-Vallet, Virginie

    2014-12-01

    For many biological and biomedical studies, it is essential to detect the production of (1)O2 and quantify its production yield. Among the available methods, detection of the characteristic 1270-nm phosphorescence of singlet oxygen by time-resolved near-infrared (TRNIR) emission constitutes the most direct and unambiguous approach. An alternative indirect method is electron paramagnetic resonance (EPR) in combination with a singlet oxygen probe. This is based on the detection of the TEMPO free radical formed after oxidation of TEMP (2,2,6,6-tetramethylpiperidine) by singlet oxygen. Although the TEMPO/EPR method has been widely employed, it can produce misleading data. This is demonstrated by the present study, in which the quantum yields of singlet oxygen formation obtained by TRNIR emission and by the TEMPO/EPR method are compared for a set of well-known photosensitizers. The results reveal that the TEMPO/EPR method leads to significant overestimation of singlet oxygen yield when the singlet or triplet excited state of the photosensitizer is efficiently quenched by TEMP, acting as electron donor. In such case, generation of the TEMP(+) radical cation, followed by deprotonation and reaction with molecular oxygen, gives rise to an EPR-detectable TEMPO signal that is not associated with singlet oxygen production. This knowledge is essential for an appropriate and error-free application of the TEMPO/EPR method in chemical, biological, and medical studies. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Detecting Position Using ARKit II: Generating Position-Time Graphs in Realtime and Further Information on Limitations of ARKit

    Science.gov (United States)

    Dilek, Ufuk; Erol, Mustafa

    2018-01-01

    ARKit is a framework which allows developers to create augmented reality apps for the iPhone and iPad. In a previous study, we had shown that it could be used to detect position in educational physics experiments and emphasized that the ability to provide position data in real-time was one of the prominent features of this newly emerging…

  15. Natural history of optical coherence tomography-detected non-flow-limiting edge dissections following drug-eluting stent implantation

    DEFF Research Database (Denmark)

    Radu, Maria D; Räber, Lorenz; Heo, Jungho

    2014-01-01

    history and clinical implications remain unclear. The objectives of the present study were to assess the morphology, healing response, and clinical outcomes of OCT-detected edge dissections using serial OCT imaging at baseline and at one year following drug-eluting stent (DES) implantation. METHODS...

  16. Effects of Kapton Sample Cell Windows on the Detection Limit of Smectite: Implications for CheMin on the Mars Science Laboratory Mission

    Science.gov (United States)

    Achilles, C. N.; Ming, Douglas W.; Morris, R. V.; Blake, D. F.

    2012-01-01

    The CheMin instrument on the Mars Science Laboratory (MSL) rover Curiosity is an X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument capable of providing the mineralogical and chemical compositions of rocks and soils on the surface of Mars. CheMin uses a microfocus X-ray tube with a Co target, transmission geometry, and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D XRD patterns and energy-dispersive X-ray histograms from powdered samples. CheMin has two different window materials used for sample cells -- Mylar and Kapton. Instrument details are provided elsewhere. Fe/Mg-smectite (e.g., nontronite) has been identified in Gale Crater, the MSL future landing site, by CRISM spectra. While large quantities of phyllosilicate minerals will be easily detected by CheMin, it is important to establish detection limits of such phases to understand capabilities and limitations of the instrument. A previous study indicated that the (001) peak of smectite at 15 Ang was detectable in a mixture of 1 wt.% smectite with olivine when Mylar is the window material for the sample cell. Complications arise when Kapton is the window material because Kapton itself also has a diffraction peak near 15 Ang (6.8 deg 2 Theta). This study presents results of mineral mixtures of smectite and olivine to determine smectite detection limits for Kapton sample cells. Because the intensity and position of the smectite (001) peak depends on the hydration state, we also analyzed mixtures with "hydrated" and "dehydrated"h smectite to examine the effects of hydration state on detection limits.

  17. Enhancement of laser-induced breakdown spectroscopy (LIBS) Detection limit using a low-pressure and short-pulse laser-induced plasma process.

    Science.gov (United States)

    Wang, Zhen Zhen; Deguchi, Yoshihiro; Kuwahara, Masakazu; Yan, Jun Jie; Liu, Ji Ping

    2013-11-01

    Laser-induced breakdown spectroscopy (LIBS) technology is an appealing technique compared with many other types of elemental analysis because of the fast response, high sensitivity, real-time, and noncontact features. One of the challenging targets of LIBS is the enhancement of the detection limit. In this study, the detection limit of gas-phase LIBS analysis has been improved by controlling the pressure and laser pulse width. In order to verify this method, low-pressure gas plasma was induced using nanosecond and picosecond lasers. The method was applied to the detection of Hg. The emission intensity ratio of the Hg atom to NO (IHg/INO) was analyzed to evaluate the LIBS detection limit because the NO emission (interference signal) was formed during the plasma generation and cooling process of N2 and O2 in the air. It was demonstrated that the enhancement of IHg/INO arose by decreasing the pressure to a few kilopascals, and the IHg/INO of the picosecond breakdown was always much higher than that of the nanosecond breakdown at low buffer gas pressure. Enhancement of IHg/INO increased more than 10 times at 700 Pa using picosecond laser with 35 ps pulse width. The detection limit was enhanced to 0.03 ppm (parts per million). We also saw that the spectra from the center and edge parts of plasma showed different features. Comparing the central spectra with the edge spectra, IHg/INO of the edge spectra was higher than that of the central spectra using the picosecond laser breakdown process.

  18. Limited effectiveness of over-the-counter plant preparations used for the treatment of urinary tract infections as inhibitors of the urease activity from Staphylococcus saprophyticus.

    Science.gov (United States)

    Deutch, C E

    2017-05-01

    Urease is a key virulence factor for the Gram-positive urinary tract pathogen Staphylococcus saprophyticus and a potential target for antimicrobial therapy. The enzyme from S. saprophyticus is unusual in that it does not contain cysteine at the active site. The aims of this study were to test 14 over-the-counter plant preparations as inhibitors of this urease and to determine whether they can prevent the increase in pH that normally occurs in bacterial cultures containing urea. Urease activity was measured colorimetrically by the formation of ammonium ions. The green tea and Uva-Ursi preparations reduced urease activity in a soluble extract of S. saprophyticus by more than 75%. Two herbal mixtures were weakly inhibitory and reduced activity by about 25%, but the other products had little or no effect. The green tea and Uva-Ursi extracts also inhibited urease activity in whole cells by more than 75%. One of the herbal products (WishGarden UTI) showed some inhibition of urease activity but the other (UTI Clear) did not. The green tea and Uva-Ursi preparations prevented the increase in pH that normally occurs when S. saprophyticus is grown in an artificial urine medium, but this was due primarily to bacterial death. The WishGarden UTI preparation could partially delay the pH increase while allowing some cells to remain viable. These results indicate that only a few of the commercially available over-the-counter plant preparations commonly used for the treatment of urinary tract infections (UTIs) can inhibit the urease activity from S. saprophyticus. While over-the-counter plant preparations may be considered an alternative to traditional antibiotics for the treatment of UTIs, they should be used with caution and a product should be matched to the properties of the virulence factors of the bacterial pathogen involved. © 2017 The Society for Applied Microbiology.

  19. X-ray Bursts in Neutron Star and Black Hole Binaries from USA Data: Detections and Upper Limits

    Energy Technology Data Exchange (ETDEWEB)

    Tournear, Derek M

    2003-02-18

    Narayan and Heyl (2002) have developed a theoretical framework to convert suitable upper limits on type I X-ray bursts from accreting black hole candidates (BHCs) into evidence for an event horizon. However, no appropriate observational limit exists in the literature. In this paper we survey 2101.2 ks of data from the Unconventional Stellar Aspect (USA) X-ray timing experiment and 5142 ks of data from the Rossi X-ray Timing Explorer (RXTE) experiment to obtain a formal constraint of this type. 1122 ks of neutron star data yield a population averaged mean burst rate of 1.69 x 10{sup -5} bursts s{sup -1} while 6081 ks of BHC data yield a 95% confidence level upper limit of 4.9 x 10{sup -7} bursts s{sup -1}. This is the first published limit of this type for Black Hole Candidates. Applying the theoretical framework of Narayan and Heyl (2002) we calculate regions of unstable luminosity where the neutron stars are expected to burst and the BHCs would be expected to burst if they had a surface. In this unstable luminosity region 464 ks of neutron star data yield an averaged mean burst rate of 4.1 x 10{sup -5} bursts s{sup -1} and 1512 ks of BHC data yield a 95% confidence level upper limit of 2.0 x 10{sup 6} bursts s{sup -1}, and a limit of > 10 {sigma} that BHCs do not burst with a rate similar to the rate of neutron stars in these unstable regions. This gives further evidence that BHCs do not have surfaces unless there is some new physics occurring on their surface.

  20. Preparation of MS2 phage-like particles and their use as potential process control viruses for detection and quantification of enteric RNA viruses in different matrices

    Directory of Open Access Journals (Sweden)

    Pavel Mikel

    2016-12-01

    Full Text Available The detection and quantification of enteric RNA viruses is based on isolation of viral RNA from the sample followed by quantitative reverse transcription polymerase chain reaction (RT-qPCR. To control the whole process of analysis and in order to guarantee the validity and reliability of results, process control viruses (PCV are used. The present article describes the process of preparation and use of such PCV– MS2 phage-like particles (MS2 PLP – in RT-qPCR detection and quantification of enteric RNA viruses. The MS2 PLP were derived from bacteriophage MS2 carrying a unique and specific de novo-constructed RNA target sequence originating from the DNA of two extinct species. The amount of prepared MS2 particles was quantified using four independent methods - UV spectrophotometry, fluorimetry, transmission electron microscopy (TEM and a specifically developed duplex RT-qPCR. To evaluate the usefulness of MS2 PLP in routine diagnostics different matrices known to harbor enteric RNA viruses (swab samples, liver tissue, serum, feces, and vegetables were artificially contaminated with specific amounts of MS2 PLP. The extraction efficiencies were calculated for each individual matrix. The prepared particles fulfill all requirements for PCV – they are very stable, non-infectious, and are genetically distinct from the target RNA viruses. Due to these properties they represent a good morphological and physiochemical model. The use of MS2 PLP as a PCV in detection and quantification of enteric RNA viruses was evaluated in different types of matrices.

  1. Utility and limitations of Addenbrooke's Cognitive Examination-Revised for detecting mild cognitive impairment in Parkinson's disease.

    Science.gov (United States)

    Komadina, Natalie C; Terpening, Zoe; Huang, Yue; Halliday, Glenda M; Naismith, Sharon L; Lewis, Simon J G

    2011-01-01

    To evaluate the utility of the Addenbrooke's Cognitive Examination-Revised (ACE-R) as a screening tool for mild cognitive impairment in Parkinson's disease (PD-MCI). PD patients underwent comprehensive neuropsychological and neurological evaluations and ACE-R assessment. The ACE-R was superior to the Mini-Mental State Exam (MMSE) in detecting PD-MCI, with a cutoff score of ≤93 offering a sensitivity of 61% and a specificity of 64%. The utility of the ACE-R in detecting PD-MCI is largely influenced by the fluency sub-domain score, and has optimal discriminability when utilized in patients with lower levels of education (≤12 years of formal schooling). The ACE-R must be used cautiously as a screening tool for PD-MCI, with results being most influenced by its fluency sub-domain score and patient education levels. Copyright © 2011 S. Karger AG, Basel.

  2. Preparation of cellulose nitrate films using a spinning disc for solid state nuclear track detection (SSNTD) applications

    International Nuclear Information System (INIS)

    Raghunath, B.; Iyer, M.R.; Samant, S.D.

    1995-01-01

    Solid state nuclear track detectors (SSNTD) are widely used in the detection and measurement of ionizing particles. Cellulose nitrate (CN) films are commonly used as SSNTD for the measurement of radon/thoron gases and their decay products. A simple method for making uniform thin CN films of various thickness has been developed. Performance of these films is compared with commercially available film. (Author)

  3. Preparation of cellulose nitrate films using a spinning disc for solid state nuclear track detection (SSNTD) applications

    Energy Technology Data Exchange (ETDEWEB)

    Raghunath, B.; Iyer, M.R. [Bhabha Atomic Research Centre, Bombay (India); Samant, S.D. [Bombay Univ. (India). Dept. of Chemical Technology

    1995-01-01

    Solid state nuclear track detectors (SSNTD) are widely used in the detection and measurement of ionizing particles. Cellulose nitrate (CN) films are commonly used as SSNTD for the measurement of radon/thoron gases and their decay products. A simple method for making uniform thin CN films of various thickness has been developed. Performance of these films is compared with commercially available film. (Author).

  4. Plant DNA Detection from Grasshopper Guts: A Step-by-Step Protocol, from Tissue Preparation to Obtaining Plant DNA Sequences

    Directory of Open Access Journals (Sweden)

    Alina Avanesyan

    2014-02-01

    Full Text Available Premise of the study: A PCR-based method of identifying ingested plant DNA in gut contents of Melanoplus grasshoppers was developed. Although previous investigations have focused on a variety of insects, there are no protocols available for plant DNA detection developed for grasshoppers, agricultural pests that significantly influence plant community composition. Methods and Results: The developed protocol successfully used the noncoding region of the chloroplast trnL (UAA gene and was tested in several feeding experiments. Plant DNA was obtained at seven time points post-ingestion from whole guts and separate gut sections, and was detectable up to 12 h post-ingestion in nymphs and 22 h post-ingestion in adult grasshoppers. Conclusions: The proposed protocol is an effective, relatively quick, and low-cost method of detecting plant DNA from the grasshopper gut and its different sections. This has important applications, from exploring plant “movement” during food consumption, to detecting plant–insect interactions.

  5. Rapid sample preparation for detection and identification of avian influenza virus from chicken faecal samples using magnetic bead microsystem

    DEFF Research Database (Denmark)

    Dhumpa, Raghuram; Bu, Minqiang; Handberg, Kurt

    2010-01-01

    Avian influenza virus (AIV) is an infectious agent of birds and mammals. AIV is causing huge economic loss and can be a threat to human health. Reverse transcriptase polymerase chain reaction (RT-PCR) has been used as a method for the detection and identification of AIV virus. Although RT...

  6. Preparation of carbon paste electrodes including poly(styrene) attached glycine-Pt(IV) for amperometric detection of glucose.

    Science.gov (United States)

    Dönmez, Soner; Arslan, Fatma; Sarı, Nurşen; Kurnaz Yetim, Nurdan; Arslan, Halit

    2014-04-15

    In this study, a novel carbon paste electrode that is sensitive to glucose was prepared using the nanoparticles modified (4-Formyl-3-methoxyphenoxymethyl) with polystyren (FMPS) with L-Glycine-Pt(IV) complexes. Polymeric nanoparticles having Pt(IV) ion were prepared from (4-Formyl-3-methoxyphenoxymethyl) polystyren, glycine and PtCl4 by template method. Glucose oxidase enzyme was immobilized to a modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Determination of glucose was carried out by oxidation of enzymatically produced H2O2 at 0.5 V vs. Ag/AgCl. Effects of pH and temperature were investigated, and optimum parameters were found to be 8.0 and 55°C, respectively. Linear working range of the electrode was 5.0×10(-6)-1.0×10(-3) M, R(2)=0.997. Storage stability and operational stability of the enzyme electrode were also studied. Glucose biosensor gave perfect reproducible results after 10 measurements with 2.3% relative standard deviation. Also, it had good storage stability (gave 53.57% of the initial amperometric response at the end of 33th day). © 2013 Published by Elsevier B.V.

  7. Detection of Salmonella enterica in meat in less than 5 hours by a low-cost and non-complex sample preparation method

    DEFF Research Database (Denmark)

    Fachmann, Mette Sofie Rousing; Löfström, Charlotta; Hoorfar, Jeffrey

    2017-01-01

    peptone water, and a real-time PCR compatible sample preparation method, based on filtration, centrifugation, and enzymatic digestion, followed by fast cycling real-time PCR detection. The method was validated in an un-paired, comparative study against the Nordic Committee on Food Analysis (NMKL......, and help contribute to improved food safety. While the cost of analysis and hands-on time of the presented rapid method were comparable to reference culture methods, the fast product release by this method can provide the meat industry with a competitive advantage. Not only will the abattoirs save costs......Salmonella is recognised as one of the most important foodborne bacteria, and has a wide health and socioeconomical impact worldwide. Fresh pork meat is one of the main sources of Salmonella and efficient and fast methods for detection are therefore necessary. Current methods for Salmonella...

  8. Detection limits of nuclear radiation and radioactivity measurements. Digital, non-selective measurements on untreated specimens. Draft. Nachweisgrenzen bei Kernstrahlungs- und Radioaktivitaetsmessungen. Digitale, nichtselektive Messungen ohne Probenbehandlung. Entwurf

    Energy Technology Data Exchange (ETDEWEB)

    1985-01-01

    The standard applies to nuclear radiation measurements where the number of pulses is recorded directly, considering exclusively the statistical character of radioactive decay and pulse counting, with the measuring time being short with regard to the half-life of radionuclides, and instrument dead-times being neglectible. The standard is intended to define suitable characteristics allowing an evaluation of detection efficiency. Two criteria are explained for given error probabilities: the sensitivity limit which allows a decision to be made as to whether the pulses recorded include values contributed by the sample; the detection limit which permits an evaluation of the measuring method in terms of suitability to the measuring goals. (orig./HP).

  9. Comparison of sensitivities and detection limits between direct excitation and secondary excitation modes in energy dispersive x-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Artz, B.E.; Short, M.A.

    1976-01-01

    A comparison was made between the direct tube excitation mode and the secondary target excitation mode using a Kevex 0810 energy dispersive x-ray fluorescence system. Relative sensitivities and detection limits were determined with two system configurations. The first configuration used a standard, high power, x-ray fluorescence tube to directly excite the specimen. Several x-ray tubes, including chromium, molybdenum, and tungsten, both filtered and not filtered, were employed. The second configuration consisted of using the x-ray tube to excite a secondary target which in turn excited the specimen. Appropriate targets were compared to the direct excitation results. Relative sensitivities and detection limits were determined for K-series lines for elements from magnesium to barium contained in a low atomic number matrix and in a high atomic number matrix

  10. Characteristics of right-sided colonic neoplasia and colonoscopy barriers limiting their early detection and prognosis: a review of the literature.

    Science.gov (United States)

    Fischbach, Wolfgang; Elsome, Rory; Amlani, Bharat

    2018-06-05

    Colonoscopy provides less protection from colorectal cancer in the right colon than the left. Areas covered: This review examines patient outcomes and colonoscopy success rates to identify factors that limit the protective effect of colonoscopy in the right colon. The MEDLINE and Embase databases were searched for literature from 2000 onwards, on the long-term outcomes and differences in screening practice between the right and left colon. In total, 12 systematic reviews (including nine meta-analyses) and 44 primary data records were included. Differences in patient outcomes and colonoscopy practice were identified between the right and left colon, suggesting that several factors, many of which disproportionally affect the right colon, impact lesion detection rates. Shorter withdrawal times reduce detection rates, while longer times significantly increase detection; mostly of adenomas in the right colon. Colonoscope attachments often only show a significant improvement in detection rates in the right colon, suggesting detection is more challenging due to visibility of the right colonic mucosa. Higher bowel cleansing grades significantly improve detection rates in the right colon compared to the left. Expert commentary: These findings confirm the need for continued improvement of colonoscopy effectiveness, and obligatory quality assessment, overall and especially in the right colon.

  11. Improvement of detection limits in the annular 241Am radioisotope-excited X-ray fluorescence analysis for minor elements of environmental sample

    International Nuclear Information System (INIS)

    Thai My Phe; Ngo Quang Huy; Nguyen Van Suc; Tran Van Luyen; Nguyen Van Mai; Dao Van Hoang; Trinh Thi Bich

    2003-01-01

    The improvement of limit detection to elements Pb, Sr, Zr, Nd, and Ba in mud samples is presented. Two ways for reducing background radiation are: 1/ choosing the optimum γ-ray-excited X-ray assembly such as scattering angle (θ), filter for primary beam, excited holder, collimator for fluorescent lines, etc; 2/ using the chemical separation method to remove major composition for matrix reduction. (NHA)

  12. Determination of undecylenic and sorbic acids in cosmetic preparations by high performance liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Bousquet, Ennio; Spadaro, A; Santagati, N A; Scalia, S; Ronsisvalle, G

    2002-11-07

    A highly sensitive and selective method for the determination of sorbic (SA) and undecylenic acid (UA) in cosmetic formulations by a high performance liquid chromatography method with electrochemical detection (ECD) is described. The pre-column derivatizations of SA and UA and the internal standard (cyclohexanoic acid (cHA)) were carried out using 1-(2,5-dihydroxyphenyl)-2-bromoethanone (2,5-DBE) as an electroactive labeling reagent previously synthesized in our lab. The resulting electroactive esters were separated by isocratic elution of a 5 micrometer Hypersil CN column with acetonitrile-acetate buffer eluent. The compounds were detected by a porous graphite electrode set at an oxidation potential of +0.45 V. The analytical method developed in this study is suitable for quality control assays of complex cosmetic formulations containing sorbic and/or UA.

  13. Testing the discrimination and detection limits of WorldView-2 imagery on a challenging invasive plant target

    Science.gov (United States)

    Robinson, T. P.; Wardell-Johnson, G. W.; Pracilio, G.; Brown, C.; Corner, R.; van Klinken, R. D.

    2016-02-01

    Invasive plants pose significant threats to biodiversity and ecosystem function globally, leading to costly monitoring and management effort. While remote sensing promises cost-effective, robust and repeatable monitoring tools to support intervention, it has been largely restricted to airborne platforms that have higher spatial and spectral resolutions, but which lack the coverage and versatility of satellite-based platforms. This study tests the ability of the WorldView-2 (WV2) eight-band satellite sensor for detecting the invasive shrub mesquite (Prosopis spp.) in the north-west Pilbara region of Australia. Detectability was challenged by the target taxa being largely defoliated by a leaf-tying biological control agent (Gelechiidae: Evippe sp. #1) and the presence of other shrubs and trees. Variable importance in the projection (VIP) scores identified bands offering greatest capacity for discrimination were those covering the near-infrared, red, and red-edge wavelengths. Wavelengths between 400 nm and 630 nm (coastal blue, blue, green, yellow) were not useful for species level discrimination in this case. Classification accuracy was tested on three band sets (simulated standard multispectral, all bands, and bands with VIP scores ≥1). Overall accuracies were comparable amongst all band-sets (Kappa = 0.71-0.77). However, mesquite omission rates were unacceptably high (21.3%) when using all eight bands relative to the simulated standard multispectral band-set (9.5%) and the band-set informed by VIP scores (11.9%). An incremental cover evaluation on the latter identified most omissions to be for objects high mapping accuracy of objects >16 m2 allows application for mapping mesquite shrubs and coalesced stands, the former not previously possible, even with 3 m resolution hyperspectral imagery. WV2 imagery offers excellent portability potential for detecting other species where spectral/spatial resolution or coverage has been an impediment. New generation satellite

  14. Applying ISO 11929:2010 Standard to detection limit calculation in least-squares based multi-nuclide gamma-ray spectrum evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Kanisch, G., E-mail: guenter.kanisch@hanse.net

    2017-05-21

    The concepts of ISO 11929 (2010) are applied to evaluation of radionuclide activities from more complex multi-nuclide gamma-ray spectra. From net peak areas estimated by peak fitting, activities and their standard uncertainties are calculated by weighted linear least-squares method with an additional step, where uncertainties of the design matrix elements are taken into account. A numerical treatment of the standard's uncertainty function, based on ISO 11929 Annex C.5, leads to a procedure for deriving decision threshold and detection limit values. The methods shown allow resolving interferences between radionuclide activities also in case of calculating detection limits where they can improve the latter by including more than one gamma line per radionuclide. The co'mmon single nuclide weighted mean is extended to an interference-corrected (generalized) weighted mean, which, combined with the least-squares method, allows faster detection limit calculations. In addition, a new grouped uncertainty budget was inferred, which for each radionuclide gives uncertainty budgets from seven main variables, such as net count rates, peak efficiencies, gamma emission intensities and others; grouping refers to summation over lists of peaks per radionuclide.

  15. Long range surface plasmon resonance with ultra-high penetration depth for self-referenced sensing and ultra-low detection limit using diverging beam approach

    Energy Technology Data Exchange (ETDEWEB)

    Isaacs, Sivan, E-mail: sivan.isaacs@gmail.com; Abdulhalim, Ibrahim [Department of Electro-Optical Engineering and TheIlse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel); NEW CREATE Programme, School of Materials Science and Engineering, 1 CREATE Way, Research Wing, #02-06/08, Singapore 138602 (Singapore)

    2015-05-11

    Using an insulator-metal-insulator structure with dielectric having refractive index (RI) larger than the analyte, long range surface plasmon (SP) resonance exhibiting ultra-high penetration depth is demonstrated for sensing applications of large bioentities at wavelengths in the visible range. Based on the diverging beam approach in Kretschmann-Raether configuration, one of the SP resonances is shown to shift in response to changes in the analyte RI while the other is fixed; thus, it can be used as a built in reference. The combination of the high sensitivity, high penetration depth and self-reference using the diverging beam approach in which a dark line is detected of the high sensitivity, high penetration depth, self-reference, and the diverging beam approach in which a dark line is detected using large number of camera pixels with a smart algorithm for sub-pixel resolution, a sensor with ultra-low detection limit is demonstrated suitable for large bioentities.

  16. Surface modification of alignment layer by ultraviolet irradiation to dramatically improve the detection limit of liquid-crystal-based immunoassay for the cancer biomarker CA125.

    Science.gov (United States)

    Su, Hui-Wen; Lee, Mon-Juan; Lee, Wei

    2015-05-01

    Liquid crystal (LC)-based biosensing has attracted much attention in recent years. We focus on improving the detection limit of LC-based immunoassay techniques by surface modification of the surfactant alignment layer consisting of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP). The cancer biomarker CA125 was detected with an array of anti-CA125 antibodies immobilized on the ultraviolet (UV)-modified DMOAP monolayer. Compared with a pristine counterpart, UV irradiation enhanced the binding affinity of the CA125 antibody and reproducibility of immunodetection in which a detection limit of 0.01 ng∕ml for the cancer biomarker CA125 was achieved. Additionally, the optical texture observed under a crossed polarized microscope was correlated with the analyte concentration. In a proof-of-concept experiment using CA125-spiked human serum as the analyte, specific binding between the CA125 antigen and the anti-CA125 antibody resulted in a distinct and concentration-dependent optical response despite the high background caused by nonspecific binding of other biomolecules in the human serum. Results from this study indicate that UVmodification of the alignment layer, as well as detection with LCs of large birefringence, contributes to the enhanced performance of the label-free LC-based immunodetection, which may be considered a promising alternative to conventional label-based methods.

  17. Trace detection of tetrahydrocannabinol (THC) with a SERS-based capillary platform prepared by the in situ microwave synthesis of AgNPs.

    Science.gov (United States)

    Yüksel, Sezin; Schwenke, Almut M; Soliveri, Guido; Ardizzone, Silvia; Weber, Karina; Cialla-May, Dana; Hoeppener, Stephanie; Schubert, Ulrich S; Popp, Jürgen

    2016-10-05

    In the present study, an ultra-sensitive and highly reproducible novel SERS-based capillary platform was developed and utilized for the trace detection of tetrahydrocannabinol (THC). The approach combines the advantages of microwave-assisted nanoparticle synthesis, plasmonics and capillary forces. By employing a microwave-assisted preparation method, glass capillaries were reproducibly coated with silver nanoparticles in a batch fabrication process that required a processing time of 3 min without needing to use any pre-surface modifications or add surfactants. The coated capillaries exhibited an excellent SERS activity with a high reproducibility and enabled the detection of low concentrations of target molecules. At the same time, only a small amount of analyte and a short and simple incubation process was required. The developed platform was applied to the spectroscopic characterization of tetrahydrocannabinol (THC) and its identification at concentration levels down to 1 nM. Thus, a highly efficient detection system for practical applications, e.g., in drug monitoring/detection, is introduced, which can be fabricated at low cost by using microwave-assisted batch synthesis techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Complexation as an approach to entrap cationic drugs into cationic nanoparticles administered intranasally for Alzheimer's disease management: preparation and detection in rat brain.

    Science.gov (United States)

    Hanafy, Amira S; Farid, Ragwa M; ElGamal, Safaa S

    2015-01-01

    Complexation was investigated as an approach to enhance the entrapment of the cationic neurotherapeutic drug, galantamine hydrobromide (GH) into cationic chitosan nanoparticles (CS-NPs) for Alzheimer's disease management intranasally. Biodegradable CS-NPs were selected due to their low production cost and simple preparation. The effects of complexation on CS-NPs physicochemical properties and uptake in rat brain were examined. Placebo CS-NPs were prepared by ionic gelation, and the parameters affecting their physicochemical properties were screened. The complex formed between GH and chitosan was detected by the FT-IR study. GH/chitosan complex nanoparticles (GH-CX-NPs) were prepared by ionic gelation, and characterized in terms of particle size, zeta potential, entrapment efficiency, in vitro release and stability for 4 and 25 °C for 3 months. Both placebo CS-NPs and GH-CX-NPs were visualized by transmission electron microscopy. Rhodamine-labeled GH-CX-NPs were prepared, administered to male Wistar rats intranasally, and their delivery to different brain regions was detected 1 h after administration using fluorescence microscopy and software-aided image processing. Optimized placebo CS-NPs and GH-CX-NPs had a diameter 182 and 190 nm, and a zeta potential of +40.4 and +31.6 mV, respectively. GH encapsulation efficiency and loading capacity were 23.34 and 9.86%, respectively. GH/chitosan complexation prolonged GH release (58.07% ± 6.67 after 72 h), improved formulation stability at 4 °C in terms of drug leakage and particle size, and showed insignificant effects on the physicochemical properties of the optimized placebo CS-NPs (p > 0.05). Rhodamine-labeled GH-CX-NPs were detected in the olfactory bulb, hippocampus, orbitofrontal and parietal cortices. Complexation is a promising approach to enhance the entrapment of cationic GH into the CS-NPs. It has insignificant effect on the physicochemical properties of CS-NPs. GH-CX-NPs were successfully

  19. Flexible and Compressible PEDOT:PSS@Melamine Conductive Sponge Prepared via One-Step Dip Coating as Piezoresistive Pressure Sensor for Human Motion Detection.

    Science.gov (United States)

    Ding, Yichun; Yang, Jack; Tolle, Charles R; Zhu, Zhengtao

    2018-05-09

    Flexible and wearable pressure sensor may offer convenient, timely, and portable solutions to human motion detection, yet it is a challenge to develop cost-effective materials for pressure sensor with high compressibility and sensitivity. Herein, a cost-efficient and scalable approach is reported to prepare a highly flexible and compressible conductive sponge for piezoresistive pressure sensor. The conductive sponge, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)@melamine sponge (MS), is prepared by one-step dip coating the commercial melamine sponge (MS) in an aqueous dispersion of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Due to the interconnected porous structure of MS, the conductive PEDOT:PSS@MS has a high compressibility and a stable piezoresistive response at the compressive strain up to 80%, as well as good reproducibility over 1000 cycles. Thereafter, versatile pressure sensors fabricated using the conductive PEDOT:PSS@MS sponges are attached to the different parts of human body; the capabilities of these devices to detect a variety of human motions including speaking, finger bending, elbow bending, and walking are evaluated. Furthermore, prototype tactile sensory array based on these pressure sensors is demonstrated.

  20. Positive detection of exfoliated colon cancer cells on linear stapler cartridges was associated with depth of tumor invasion and preoperative bowel preparation in colon cancer.

    Science.gov (United States)

    Ikehara, Kishiko; Endo, Shungo; Kumamoto, Kensuke; Hidaka, Eiji; Ishida, Fumio; Tanaka, Jun-Ichi; Kudo, Shin-Ei

    2016-08-31

    The aim of this study was to investigate exfoliated cancer cells (ECCs) on linear stapler cartridges used for anastomotic sites in colon cancer. We prospectively analyzed ECCs on linear stapler cartridges used for anastomosis in 100 colon cancer patients who underwent colectomy. Having completed the functional end-to-end anastomosis, the linear stapler cartridges were irrigated with saline, which was collected for cytological examination and cytological diagnoses were made by board-certified pathologists based on Papanicolaou staining. The detection rate of ECCs on the linear stapler cartridges was 20 %. Positive detection of ECCs was significantly associated with depth of tumor invasion (p = 0.012) and preoperative bowel preparation (p = 0.003). There were no marked differences between ECC-positive and ECC-negative groups in terms of the operation methods, tumor location, histopathological classification, and surgical margins. Since ECCs were identified on the cartridge of the linear stapler used for anastomosis, preoperative mechanical bowel preparation using polyethylene glycol solution and cleansing at anastomotic sites using tumoricidal agents before anastomosis may be necessary to decrease ECCs in advanced colon cancer.

  1. Detection of Acute and Early HIV-1 Infections in an HIV Hyper-Endemic Area with Limited Resources.

    Directory of Open Access Journals (Sweden)

    Simnikiwe H Mayaphi

    Full Text Available Two thirds of the world's new HIV infections are in sub-Saharan Africa. Acute HIV infection (AHI is the time of virus acquisition until the appearance of HIV antibodies. Early HIV infection, which includes AHI, is the interval between virus acquisition and establishment of viral load set-point. This study aimed to detect acute and early HIV infections in a hyper-endemic setting.This was a cross-sectional diagnostic study that enrolled individuals who had negative rapid HIV results in five clinics in South Africa. Pooled nucleic acid amplification testing (NAAT was performed, followed by individual sample testing in positive pools. NAAT-positive participants were recalled to the clinics for confirmatory testing and appropriate management. HIV antibody, p24 antigen, Western Blot and avidity tests were performed for characterization of NAAT-positive samples.The study enrolled 6910 individuals with negative rapid HIV results. Median age was 27 years (interquartile range {IQR}: 23-31. NAAT was positive in 55 samples, resulting in 0.8% newly diagnosed HIV-infected individuals (95% confidence interval {CI}: 0.6-1.0. The negative predictive value for rapid HIV testing was 99.2% (95% CI: 99.0-99.4. Characterization of NAAT-positive samples revealed that 0.04% (95% CI: 0.000-0.001 had AHI, 0.3% (95% CI: 0.1-0.4 had early HIV infection, and 0.5% (95% CI: 0.5-0.7 had chronic HIV infection. Forty-seven (86% of NAAT-positive participants returned for follow-up at a median of 4 weeks (IQR: 2-8. Follow-up rapid tests were positive in 96% of these participants.NAAT demonstrated that a substantial number of HIV-infected individuals are misdiagnosed at South African points-of-care. Follow-up rapid tests done within a 4 week interval detected early and chronic HIV infections initially missed by rapid HIV testing. This may be a practical and affordable strategy for earlier detection of these infections in resource-constrained settings. Newer molecular tests that can

  2. Limitations in SELDI-TOF MS whole serum proteomic profiling with IMAC surface to specifically detect colorectal cancer

    International Nuclear Information System (INIS)

    Wang, Qi; Gu, Jin; Shen, Jing; Li, Zhen-fu; Jie, Jian-zheng; Wang, Wen-yue; Wang, Jin; Zhang, Zhong-tao; Li, Zhi-xia; Yan, Li

    2009-01-01

    Surface enhanced laser desorption and ionization time-of-flight mass spectrometry (SELDI-TOF-MS) analysis on serum samples was reported to be able to detect colorectal cancer (CRC) from normal or control patients. We carried out a validation study of a SELDI-TOF MS approach with IMAC surface sample processing to identify CRC. A retrospective cohort of 338 serum samples including 154 CRCs, 67 control cancers and 117 non-cancerous conditions was profiled using SELDI-TOF-MS. No CRC 'specific' classifier was found. However, a classifier consisting of two protein peaks separates cancer from non-cancerous conditions with high accuracy. In this study, the SELDI-TOF-MS-based protein expression profiling approach did not perform to identify CRC. However, this technique is promising in distinguishing patients with cancer from a non-cancerous population; it may be useful for monitoring recurrence of CRC after treatment

  3. Using European travellers as an early alert to detect emerging pathogens in countries with limited laboratory resources

    Directory of Open Access Journals (Sweden)

    Grais Rebecca

    2007-01-01

    Full Text Available Abstract Background The volume, extent and speed of travel have dramatically increased in the past decades, providing the potential for an infectious disease to spread through the transportation network. By collecting information on the suspected place of infection, existing surveillance systems in industrialized countries may provide timely information for areas of the world without adequate surveillance currently in place. We present the results of a case study using reported cases of Shigella dysenteriae serotype 1 (Sd1 in European travellers to detect "events" of Sd1, related to either epidemic cases or endemic cases in developing countries. Methods We identified papers from a Medline search for reported events of Sd1 from 1940 to 2002. We requested data on shigella infections reported to the responsible surveillance entities in 17 European countries. Reports of Sd1 from the published literature were then compared with Sd1 notified cases among European travellers from 1990 to 2002. Results Prior to a large epidemic in 1999–2000, no cases of Sd1 had been identified in West Africa. However, if travellers had been used as an early warning, Sd1 could have been identified in this region as earlier as 1992. Conclusion This project demonstrates that tracking diseases in European travellers could be used to detect emerging disease in developing countries. This approach should be further tested with a view to the continuous improvement of national health surveillance systems and existing European networks, and may play a significant role in aiding the international public health community to improve infectious disease control.

  4. Technetium-99m labelled hydrazinonicotinamido human non-specific polyclonal immunoglobulin G for detection of infectious foci: a comparison with two other technetium-labelled immunoglobulin preparations

    Energy Technology Data Exchange (ETDEWEB)

    Claessens, R.A.M.J. [University Hospital Nijmegen, Department of Nuclear Medicine, P.O. Box 9101, 6500 HB Nijmegen (Netherlands); Boerman, O.C. [University Hospital Nijmegen, Department of Nuclear Medicine, P.O. Box 9101, 6500 HB Nijmegen (Netherlands); Koenders, E.B. [University Hospital Nijmegen, Department of Nuclear Medicine, P.O. Box 9101, 6500 HB Nijmegen (Netherlands); Oyen, W.J.G. [University Hospital Nijmegen, Department of Nuclear Medicine, P.O. Box 9101, 6500 HB Nijmegen (Netherlands); Meer, J.W.M. van der [University Hospital Nijmegen, Department of Nuclear Medicine, P.O. Box 9101, 6500 HB Nijmegen (Netherlands); Corstens, F.H.M. [University Hospital Nijmegen, Department of Nuclear Medicine, P.O. Box 9101, 6500 HB Nijmegen (Netherlands)

    1996-04-01

    In this study we compared the tissue distribution of three different {sup 99m}Tc-hIgG preparations in groups of five Wistar rats with a focal intramuscular infection with Staphylococcus aureus. We compared {sup 99m}Tc-HYNIC-hIgG with {sup 99m}Tc-hIgG labelled via the so-called Schwarz method (reduction of disulphide bonds) and with the {sup 99m}Tc-labelled commercially available Technescan-HIG. Unlike the HYNIC linker, in the two other labelling methods free sulph-hydryl groups are involved in the binding of {sup 99m}Tc. High-performance liquid chromatography analysis of the labelled preparations and of plasma samples revealed aggregate or polymer formation in all three agents; this was least pronounced in the product labelled by means of the Schwarz method. The tested preparations did not show signs of degradation in vitro. The difference in linker chemistry was reflected in the tissue distribution. Thus the biodistribution of {sup 99m}Tc-HYNIC-hIgG was significantly different from the distribution of the two other preparations: abscess (1.4%{+-}0.2%ID/g), muscle, liver, spleen, plasma, lung, bone marrow, and small intestine concentrations were higher at 24 h p.i.; kidney uptake (1.19%{+-}0.08%ID/g) was significantly lower. The abscess-to-plasma and the abscess-to-muscle ratios (0.5 and 11, respectively), however, were in the same range for the three preparations tested. Quantitative analysis of the scintigraphs revealed that the total body clearance of {sup 99m}Tc-HYNIC-hIgG was significantly slower than for the other agents. The abscess uptake of {sup 99m}Tc-HYNIC-hIgG as a percentage of the remaining body activity was significantly higher. Based on its high abscess uptake, its low uptake in the kidneys and the high percentage of its abscess uptake in relation to the remaining body activity, we conclude that {sup 99m}Tc-HYNIC-hIgG seems superior to the two other preparations tested for the detection of infections. (orig.). With 7 figs., 2 tabs.

  5. The limitations on organic detection in Mars-like soils by thermal volatilization-gas chromatography-MS and their implications for the Viking results.

    Science.gov (United States)

    Navarro-González, Rafael; Navarro, Karina F; de la Rosa, José; Iñiguez, Enrique; Molina, Paola; Miranda, Luis D; Morales, Pedro; Cienfuegos, Edith; Coll, Patrice; Raulin, François; Amils, Ricardo; McKay, Christopher P

    2006-10-31

    The failure of Viking Lander thermal volatilization (TV) (without or with thermal degradation)-gas chromatography (GC)-MS experiments to detect organics suggests chemical rather than biological interpretations for the reactivity of the martian soil. Here, we report that TV-GC-MS may be blind to low levels of organics on Mars. A comparison between TV-GC-MS and total organics has been conducted for a variety of Mars analog soils. In the Antarctic Dry Valleys and the Atacama and Libyan Deserts we find 10-90 mug of refractory or graphitic carbon per gram of soil, which would have been undetectable by the Viking TV-GC-MS. In iron-containing soils (jarosites from Rio Tinto and Panoche Valley) and the Mars simulant (palogonite), oxidation of the organic material to carbon dioxide (CO(2)) by iron oxides and/or their salts drastically attenuates the detection of organics. The release of 50-700 ppm of CO(2) by TV-GC-MS in the Viking analysis may indicate that an oxidation of organic material took place. Therefore, the martian surface could have several orders of magnitude more organics than the stated Viking detection limit. Because of the simplicity of sample handling, TV-GC-MS is still considered the standard method for organic detection on future Mars missions. We suggest that the design of future organic instruments for Mars should include other methods to be able to detect extinct and/or extant life.

  6. The limitations on organic detection in Mars-like soils by thermal volatilization–gas chromatography–MS and their implications for the Viking results

    Science.gov (United States)

    Navarro-González, Rafael; Navarro, Karina F.; de la Rosa, José; Iñiguez, Enrique; Molina, Paola; Miranda, Luis D.; Morales, Pedro; Cienfuegos, Edith; Coll, Patrice; Raulin, François; Amils, Ricardo; McKay, Christopher P.

    2006-01-01

    The failure of Viking Lander thermal volatilization (TV) (without or with thermal degradation)–gas chromatography (GC)–MS experiments to detect organics suggests chemical rather than biological interpretations for the reactivity of the martian soil. Here, we report that TV–GC–MS may be blind to low levels of organics on Mars. A comparison between TV–GC–MS and total organics has been conducted for a variety of Mars analog soils. In the Antarctic Dry Valleys and the Atacama and Libyan Deserts we find 10–90 μg of refractory or graphitic carbon per gram of soil, which would have been undetectable by the Viking TV–GC–MS. In iron-containing soils (jarosites from Rio Tinto and Panoche Valley) and the Mars simulant (palogonite), oxidation of the organic material to carbon dioxide (CO2) by iron oxides and/or their salts drastically attenuates the detection of organics. The release of 50–700 ppm of CO2 by TV–GC–MS in the Viking analysis may indicate that an oxidation of organic material took place. Therefore, the martian surface could have several orders of magnitude more organics than the stated Viking detection limit. Because of the simplicity of sample handling, TV–GC–MS is still considered the standard method for organic detection on future Mars missions. We suggest that the design of future organic instruments for Mars should include other methods to be able to detect extinct and/or extant life. PMID:17060639

  7. Quantum state detection and state preparation based on cavity-enhanced nonlinear interaction of atoms with single photon

    Science.gov (United States)

    Hosseini, Mahdi

    Our ability to engineer quantum states of light and matter has significantly advanced over the past two decades, resulting in the production of both Gaussian and non-Gaussian optical states. The resulting tailored quantum states enable quantum technologies such as quantum optical communication, quantum sensing as well as quantum photonic computation. The strong nonlinear light-atom interaction is the key to deterministic quantum state preparation and quantum photonic processing. One route to enhancing the usually weak nonlinear light-atom interactions is to approach the regime of cavity quantum electrodynamics (cQED) interaction by means of high finesse optical resonators. I present results from the MIT experiment of large conditional cross-phase modulation between a signal photon, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. I also present a scheme to probabilistically change the amplitude and phase of a signal photon qubit to, in principle, arbitrary values by postselection on a control photon that has interacted with that state. Notably, small changes of the control photon polarization measurement basis by few degrees can substantially change the amplitude and phase of the signal state. Finally, I present our ongoing effort at Purdue to realize similar peculiar quantum phenomena at the single photon level on chip scale photonic systems.

  8. Development of a sensor prepared by entrapment of MIP particles in electrosynthesised polymer films for electrochemical detection of ephedrine.

    Science.gov (United States)

    Mazzotta, E; Picca, R A; Malitesta, C; Piletsky, S A; Piletska, E V

    2008-02-28

    A voltammetric sensor for (-)-ephedrine has been prepared by a novel approach based on immobilisation of an imprinted polymer for ephedrine (MIPE) in an electrosynthesised polypyrrole (PPY) film. Composite films were grown potentiostatically at 1.0 V vs. Pt (QRE) on a glassy carbon electrode using an unconventional "upside-down" (UD) geometry for the three-electrode cell. As a consequence, a high MIP loading was obtained, as revealed by SEM. The sensor response was evaluated, after overoxidation of PPY matrix, by cyclic voltammetry after pre-concentration in a buffered solution of analyte in 0.5-3 mM concentration range. An ephedrine peak at approximately 0.9 V increasing with concentration and saturating at high concentrations was evident. PPY-modified electrode showed a response, which was distinctly lower than the MIP response for the same concentration of the template. The effect of potential interferences including compounds usually found in human fluids (ascorbic acid, uric acid, urea, glucose, sorbitol, glycine, dopamine) was examined.

  9. A discussion on the merits and limitations of using drive-by monitoring to detect localised damage in a bridge

    Science.gov (United States)

    Hester, David; González, Arturo

    2017-06-01

    Given the large number of bridges that currently have no instrumentation, there are obvious advantages in monitoring the condition of a bridge by analysing the response of a vehicle crossing it. As a result, the last two decades have seen a rise in the research attempting to solve the problem of identifying damage in a bridge from vehicle measurements. This paper examines the theoretical feasibility and practical limitations of a drive-by system in identifying damage associated to localised stiffness losses. First, the nature of the damage feature that is sought within the vehicle response needs to be characterized. For this purpose, the total vehicle response is considered to be made of 'static' and 'dynamic' components, and where the bridge has experienced a localised loss in stiffness, an additional 'damage' component. Understanding the nature of this 'damage' component is crucial to have an informed discussion on how damage can be identified and localised. Leveraging this new understanding, the authors propose a wavelet-based drive-by algorithm. By comparing the effect of the 'damage' component to other key effects defining the measurements such as 'vehicle speed', the 'road profile' and 'noise' on a wavelet contour plot, it is possible to establish if there is a frequency range where drive-by can be successful. The algorithm uses then specific frequency bands to improve the sensitivity to damage with respect to limitations imposed by Vehicle-Bridge vibrations. Recommendations on the selection of the mother wavelet and frequency band are provided. Finally, the paper discusses the impact of noise and road profile on the ability of the approach to identify damage and how periodic measurements can be effective at monitoring localised stiffness changes.

  10. Variation in the limit-of-detection of the ProSpecT Campylobacter microplate enzyme immunoassay in stools spiked with emerging Campylobacter species.

    Science.gov (United States)

    Bojanić, Krunoslav; Midwinter, Anne Camilla; Marshall, Jonathan Craig; Rogers, Lynn Elizabeth; Biggs, Patrick Jon; Acke, Els

    2016-08-01

    Campylobacter enteritis in humans is primarily associated with C. jejuni/coli infection. The impact of other Campylobacter spp. is likely to be underestimated due to the bias of culture methods towards Campylobacter jejuni/coli diagnosis. Stool antigen tests are becoming increasingly popular and appear generally less species-specific. A review of independent studies of the ProSpecT® Campylobacter Microplate enzyme immunoassay (EIA) developed for C. jejuni/coli showed comparable diagnostic results to culture methods but the examination of non-jejuni/coli Campylobacter spp. was limited and the limit-of-detection (LOD), where reported, varied between studies. This study investigated LOD of EIA for Campylobacter upsaliensis, Campylobacter hyointestinalis and Campylobacter helveticus spiked in human stools. Multiple stools and Campylobacter isolates were used in three different concentrations (10(4)-10(9)CFU/ml) to reflect sample heterogeneity. All Campylobacter species evaluated were detectable by EIA. Multivariate analysis showed LOD varied between Campylobacter spp. and faecal consistency as fixed effects and individual faecal samples as random effects. EIA showed excellent performance in replicate testing for both within and between batches of reagents, in agreement between visual and spectrophotometric reading of results, and returned no discordance between the bacterial concentrations within independent dilution test runs (positive results with lower but not higher concentrations). This study shows how limitations in experimental procedures lead to an overestimation of consistency and uniformity of LOD for EIA that may not hold under routine use in diagnostic laboratories. Benefits and limitations for clinical practice and the influence on estimates of performance characteristics from detection of multiple Campylobacter spp. by EIA are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Limitations of Using IL-17A and IFN-γ-Induced Protein 10 to Detect Bovine Tuberculosis

    Science.gov (United States)

    Xin, Ting; Gao, Xintao; Yang, Hongjun; Li, Pingjun; Liang, Qianqian; Hou, Shaohua; Sui, Xiukun; Guo, Xiaoyu; Yuan, Weifeng; Zhu, Hongfei; Ding, Jiabo; Jia, Hong

    2018-01-01

    Bovine tuberculosis (bTB) is primarily caused by infection with Mycobacterium bovis, which belongs to the Mycobacterium tuberculosis complex. The airborne route is considered the most common for transmission of M. bovis, and more than 15% of cattle with bTB shed the Mycobacterium, which can be detect by nested PCR to amplify mycobacterial mpb70 from a nasal swab from a cow. To screen for cytokines fostering early and accurate detection of bTB, peripheral blood mononuclear cells were isolated from naturally M. bovis-infected, experimentally M. bovis 68002-infected, and uninfected cattle, then these cells were stimulated by PPD-B, CFP-10-ESAT-6 (CE), or phosphate-buffered saline (PBS) for 6 h. The levels of interferon gamma (IFN-γ), IFN-γ-induced protein 10 (IP-10), IL-6, IL-12, IL-17A, and tumor necrosis factor alpha mRNA were measured using real-time PCR. To explore the cytokines associated with different periods of M. bovis infection, cattle were divided into three groups: PCR-positive, PCR-negative, and uninfected using the tuberculin skin test, CFP-10/ESAT-6/TB10.4 protein cocktail-based skin test, IFN-γ release assay (IGRA), CFP-10/ESAT-6 (CE)-based IGRA, and nested PCR. The expression of IP-10, IL-17A, and IFN-γ proteins induced by PPD-B, CE, or PBS was detected by ELISA. The results showed that levels of PPD-B-stimulated IL-17A and IP-10 (mRNA and protein), and CE-induced IP-10 (mRNA and protein) were significantly higher in cattle naturally or experimentally infected with M. bovis than in those that were uninfected. The levels of PPD-B- or CE-induced IL-17A and IP-10 (protein) could be used to differentiate M. bovis-infected calves from uninfected ones for 6 to 30 weeks post-infection, whereas PPD-B- and CE-induced IP-10 and IL-17A mRNA expression could be used to differentiate M. bovis-infected calves from uninfected ones between 6 and 58 weeks post-infection. However, CE-induced IL-17A (protein) was not a reliable indicator of M. bovis infection

  12. Use and limitations of radiolabelled anti-CEA antibodies and their fragments for photoscanning detection of human colorectal carcinomas

    Energy Technology Data Exchange (ETDEWEB)

    Mach, J P; Forni, M; Ritschard, J; Buchegger, F; Carrel, S; Widgren, S; Donath, A; Alberto, P [Lausanne Univ. (Switzerland)

    1980-08-01

    Fifty-three patients with histologically proven carcinoma were injected with highly purified (/sup 131/I)-labelled goat antibodies or fragments of antibodies against carcinoembryonic antigen (CEA). Each patient was tested by external photoscanning 4, 24, 36, 48h after injection. In 22 patients (16 of 38 injected with intact antibodies, 5 of 13 with F(ab')/sub 2/ fragments and 1 of 2 with Fab' fragments), an increased concentration of /sup 131/I radioactivity corresponding to the previously known tumor location was detected by photoscanning 36-48 h after injection. Blood pool and secreted radioactivity was determined in all patients by injecting 15 min after scanning, (sup(99m)Tc)-labeled normal serum albumin and free sup(99m)TcO/sub 4//sup -/. The computerized subtraction of sup(99m)Tc from /sup 131/I radioactivity enhanced the definition of tumor localization in the 22 positive patients. However, in spite of the computerized subtraction, interpretation of the scans remained doubtful for 12 patients and was entirely negative for 19 additional patients.

  13. Preliminary minimum detectable limit measurements in 208-L drums for selected actinide isotopes in mock-waste matrices

    International Nuclear Information System (INIS)

    Camp, D.C.; Wang, Tzu-Fang; Martz, H.E.

    1992-01-01

    Preliminary minimum detectable levels (MDLS) of selected actinide isotopes have been determined in full-scale, 55-gallon drums filled with a range of mock-waste materials from combustibles (0.14 g/CM 3 ) to sand (1.7 g/CM 3 ). Measurements were recorded from 100 to 10,000 seconds with selected actinide sources located in these drums at an edge position, on the center axis of a drum and midway between these two positions. Measurements were also made with a 166 Ho source to evaluate the attenuation of these mock-matrix materials as a function of energy. By knowing where the source activity is located within a drum, our preliminary results show that a simply collimated 90% HPGE detector can differentiate between TRU (>100 nCi/g) and LLW amounts of 239 Pu in only 100s of measurement time and with sufficient accuracy in both low and medium density, low Z materials. Other actinides measured so far include 235 U, 241 Am, and 244 Cm. These measurements begin to establish the probable MDLs achievable in the nondestructive assays of real waste drums when using active and passive CT. How future measurements may differ from these preliminary measurements is also discussed

  14. Empty virions in AAV8 vector preparations reduce transduction efficiency and may cause total viral particle dose-limiting side effects

    Directory of Open Access Journals (Sweden)

    Kai Gao

    2014-01-01

    Full Text Available Empty virions are inadvertent by-products of recombinant adeno-associated virus (rAAV packaging process, resulting in vector lots with mixtures of full and empty virions at variable ratios. Impact of empty virions on the efficiency and side effects of rAAV transduction has not been well characterized. Here, we generated partially and completely empty AAV8 virions, fully packaged rAAV8 lots, and mixtures of empty and fully packaged virions with variable ratios of empty virions. The aforementioned dosing formulations of rAAV8 expressing either cellular (EGFP (enhanced green fluorescent protein or nuclear-targeted (n LacZ or secreted (human α1-antitrypsin (hA1AT reporter genes were intravenously injected into two different mouse strains, followed by analyses of transgene expressions and serum alanine aminotransferase (ALT levels at different time points. We found that addition of empty particles to the fixed doses of rAAV8 preparations repressed liver transduction up to 64% (serum hA1AT and 44% (nLacZ in C57BL/6 mice, respectively. The similar trend in inhibiting EGFP expression together with concurrent elevations of serum ALT levels were observed in the BALB/c mice, indicating that empty particles may also exacerbate side effects of rAAV8 EGFP transduction. Our results suggest that removal of empty particles from rAAV preparations may improve efficacy and safety of AAV in clinical applications.

  15. Limit of detection of a fiber optics gyroscope using a super luminescent radiation source; Limite de deteccion de un giroscopio de fibra optica usando una fuente de radiacion superluminiscente

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval R, G.E. [Laboratorio de Optica Aplicada, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510 Mexico D.F. (Mexico); Nikolaev, V.A. [Departamento de Optica y Radiofisica Cuantica, Universidad Estatal de Telecomunicaciones de San Petersburgo, M.A. Bonch-Bruyevich, Kanal Moika 61, Saint Petersburg 191186, (Russian Federation)

    2003-07-01

    The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which is determined with the shot noise. (Author)

  16. Ag/α-Fe{sub 2}O{sub 3} hollow microspheres: Preparation and application for hydrogen peroxide detection

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Xinyuan; Wu, Zhiping; Liao, Fang, E-mail: liaozhang2003@163.com; Zhang, Tingting; Guo, Tingting

    2015-09-15

    In this paper, we demonstrated a simple approach for preparing α-Fe{sub 2}O{sub 3} hollow spheres by mixing ferric nitrate aqueous and glucose in 180 °C. The glucose was found to act as a soft template in the process of α-Fe{sub 2}O{sub 3} hollow spheres formation. Ag/α-Fe{sub 2}O{sub 3} hollow nanocomposite was obtained under UV irradiation without additional reducing agents or initiators. Synthesized Ag/α-Fe{sub 2}O{sub 3} hollow composites exhibited remarkable catalytic performance toward H{sub 2}O{sub 2} reduction. The electrocatalytic activity mechanism of Ag/α-Fe{sub 2}O{sub 3}/GCE were discussed toward the reduction of H{sub 2}O{sub 2} in this paper. - Graphical abstract: Glucose is carbonized as carbon balls in the 180 °C hydrothermal carbonization process, which plays a role of a soft template. Carbon spherical shell is rich in many hydroxyls, which have good hydrophilicity and surface reactivity. When Fe(NO{sub 3}){sub 3} is added to the aqueous solution of Glucose, the hydrophilic -OH will adsorb Fe{sup 3+} to form coordination compound by coordination bond. α-FeOOH is formed on the surface of carbon balls by hydrothermal reaction. After calcination at 500 °C, carbon spheres react with oxygen to form carbon dioxide, which disappears in the air. Meanwhile α-FeOOH is calcined to form α-Fe{sub 2}O{sub 3} hollow spheres.

  17. Study of boron detection limit using the in-air PIGE set-up at LAMFI-USP

    Energy Technology Data Exchange (ETDEWEB)

    Moro, M. V.; Silva, T. F.; Trindade, G. F.; Added, N.; Tabacniks, M. H. [Institute of Physics, University of São Paulo, SP (Brazil)

    2014-11-11

    The quantification of small amounts of boron in materials is of extreme importance in different areas of materials science. Boron is an important contaminant and also a silicon dopant in the semiconductor industry. Boron is also extensively used in nuclear power plants, either for neutron shielding or for safety control and boron is an essential nutrient for life, either vegetable or animal. The production of silicon solar cells, by refining metallurgical-grade silicon (MG-Si) requires the control and reduction of several silicon contaminants to very low concentration levels. Boron is one of the contaminants of solar-grade silicon (SG-Si) that must be controlled and quantified at sub-ppm levels. In the metallurgical purification, boron quantification is usually made by Inductive Coupled Plasma Mass Spectrometry, (ICP-MS) but the results need to be verified by an independent analytical method. In this work we present the results of the analysis of silicon samples by Particle Induced Gamma-Ray Emission (PIGE) aiming the quantification of low concentrations of boron. PIGE analysis was carried out using the in-air external beam line of the Laboratory for Materials Analysis with Ion Beams (LAMFI-USP) by the {sup 10}B(p,αγ({sup 7}Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 10{sup 16} at/cm{sup 2}.

  18. Study of boron detection limit using the in-air PIGE set-up at LAMFI-USP

    Science.gov (United States)

    Moro, M. V.; Silva, T. F.; Trindade, G. F.; Added, N.; Tabacniks, M. H.

    2014-11-01

    The quantification of small amounts of boron in materials is of extreme importance in different areas of materials science. Boron is an important contaminant and also a silicon dopant in the semiconductor industry. Boron is also extensively used in nuclear power plants, either for neutron shielding or for safety control and boron is an essential nutrient for life, either vegetable or animal. The production of silicon solar cells, by refining metallurgical-grade silicon (MG-Si) requires the control and reduction of several silicon contaminants to very low concentration levels. Boron is one of the contaminants of solar-grade silicon (SG-Si) that must be controlled and quantified at sub-ppm levels. In the metallurgical purification, boron quantification is usually made by Inductive Coupled Plasma Mass Spectrometry, (ICP-MS) but the results need to be verified by an independent analytical method. In this work we present the results of the analysis of silicon samples by Particle Induced Gamma-Ray Emission (PIGE) aiming the quantification of low concentrations of boron. PIGE analysis was carried out using the in-air external beam line of the Laboratory for Materials Analysis with Ion Beans (LAMFI-USP) by the 10B ( p ,αγ(7Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 1016 at/cm2.

  19. Study of boron detection limit using the in-air PIGE set-up at LAMFI-USP

    International Nuclear Information System (INIS)

    Moro, M. V.; Silva, T. F.; Trindade, G. F.; Added, N.; Tabacniks, M. H.

    2014-01-01

    The quantification of small amounts of boron in materials is of extreme importance in different areas of materials science. Boron is an important contaminant and also a silicon dopant in the semiconductor industry. Boron is also extensively used in nuclear power plants, either for neutron shielding or for safety control and boron is an essential nutrient for life, either vegetable or animal. The production of silicon solar cells, by refining metallurgical-grade silicon (MG-Si) requires the control and reduction of several silicon contaminants to very low concentration levels. Boron is one of the contaminants of solar-grade silicon (SG-Si) that must be controlled and quantified at sub-ppm levels. In the metallurgical purification, boron quantification is usually made by Inductive Coupled Plasma Mass Spectrometry, (ICP-MS) but the results need to be verified by an independent analytical method. In this work we present the results of the analysis of silicon samples by Particle Induced Gamma-Ray Emission (PIGE) aiming the quantification of low concentrations of boron. PIGE analysis was carried out using the in-air external beam line of the Laboratory for Materials Analysis with Ion Beams (LAMFI-USP) by the 10 B(p,αγ( 7 Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 10 16 at/cm 2

  20. Improvements on Near Real Time Detection of Volcanic Ash Emissions for Emergency Monitoring with Limited Satellite Bands

    Directory of Open Access Journals (Sweden)

    Torge Steensen

    2015-03-01

    Full Text Available Quantifying volcanic ash emissions syneruptively is an important task for the global aviation community. However, due to the near real time nature of volcano monitoring, many parameters important for accurate ash mass estimates cannot be obtained easily. Even when using the best possible estimates of those parameters, uncertainties associated with the ash masses remain high, especially if the satellite data is only available in the traditional 10.8 and 12.0 μm bands. To counteract this limitation, we developed a quantitative comparison between the ash extents in satellite and model data. The focus is the manual cloud edge definition based on the available satellite reverse absorption (RA data as well as other knowledge like pilot reports or ground-based observations followed by an application of the Volcanic Ash Retrieval on the defined subset with an RA threshold of 0 K. This manual aspect, although subjective to the experience of the observer, can show a significant improvement as it provides the ability to highlight ash that otherwise would be obscured by meteorological clouds or, by passing over different surfaces with unaccounted temperatures, might be lost entirely and thus remains undetectable for an automated satellite approach. We show comparisons to Volcanic Ash Transport and Dispersion models and outline a quantitative match as well as percentages of overestimates based on satellite or dispersion model data which can be converted into a level of reliability for near real time volcano monitoring. 

  1. The Capabilities and Limitation of Remote Visual Methods to Detect Service-Induced Cracks in Reactor Components

    International Nuclear Information System (INIS)

    Cumblidge, Stephen E.; Doctor, Steven R.; Anderson, Michael T.

    2006-01-01

    detect cracks of various widths under ideal conditions.

  2. Matrix removal in state of the art sample preparation methods for serum by charged aerosol detection and metabolomics-based LC-MS.

    Science.gov (United States)

    Schimek, Denise; Francesconi, Kevin A; Mautner, Anton; Libiseller, Gunnar; Raml, Reingard; Magnes, Christoph

    2016-04-07

    Investigations into sample preparation procedures usually focus on analyte recovery with no information provided about the fate of other components of the sample (matrix). For many analyses, however, and particularly those using liquid chromatography-mass spectrometry (LC-MS), quantitative measurements are greatly influenced by sample matrix. Using the example of the drug amitriptyline and three of its metabolites in serum, we performed a comprehensive investigation of nine commonly used sample clean-up procedures in terms of their suitability for preparing serum samples. We were monitoring the undesired matrix compounds using a combination of charged aerosol detection (CAD), LC-CAD, and a metabolomics-based LC-MS/MS approach. In this way, we compared analyte recovery of protein precipitation-, liquid-liquid-, solid-phase- and hybrid solid-phase extraction methods. Although all methods provided acceptable recoveries, the highest recovery was obtained by protein precipitation with acetonitrile/formic acid (amitriptyline 113%, nortriptyline 92%, 10-hydroxyamitriptyline 89%, and amitriptyline N-oxide 96%). The quantification of matrix removal by LC-CAD showed that the solid phase extraction method (SPE) provided the lowest remaining matrix load (48-123 μg mL(-1)), which is a 10-40 fold better matrix clean-up than the precipitation- or hybrid solid phase extraction methods. The metabolomics profiles of eleven compound classes, comprising 70 matrix compounds showed the trends of compound class removal for each sample preparation strategy. The collective data set of analyte recovery, matrix removal and matrix compound profile was used to assess the effectiveness of each sample preparation method. The best performance in matrix clean-up and practical handling of small sample volumes was showed by the SPE techniques, particularly HLB SPE. CAD proved to be an effective tool for revealing the considerable differences between the sample preparation methods. This detector can

  3. Comparison of commercial DNA preparation kits for the detection of Brucellae in tissue using quantitative real-time PCR

    Directory of Open Access Journals (Sweden)

    Straube Eberhard

    2010-04-01

    Full Text Available Abstract Background The detection of Brucellae in tissue specimens using PCR assays is difficult because the amount of bacteria is usually low. Therefore, optimised DNA extraction methods are critical. The aim of this study was to assess the performance of commercial kits for the extraction of Brucella DNA. Methods Five kits were evaluated using clinical specimens: QIAamp™ DNA Mini Kit (QIAGEN, peqGold™ Tissue DNA Mini Kit (PeqLab, UltraClean™ Tissue and Cells DNA Isolation Kit (MoBio, DNA Isolation Kit for Cells and Tissues (Roche, and NucleoSpin™ Tissue (Macherey-Nagel. DNA yield was determined using a quantitative real-time PCR assay targeting IS711 that included an internal amplification control. Results Kits of QIAGEN and Roche provided the highest amount of DNA, Macherey-Nagel and Peqlab products were intermediate whereas MoBio yielded the lowest amount of DNA. Differences were significant (p Conclusions We observed differences in DNA yield as high as two orders of magnitude for some samples between the best and the worst DNA extraction kits and inhibition was observed occasionally. This indicates that DNA purification may be more relevant than expected when the amount of DNA in tissue is very low.

  4. A Facile Approach to Preparing Molecularly Imprinted Chitosan for Detecting 2,4,6-Tribromophenol with a Widely Linear Range

    Directory of Open Access Journals (Sweden)

    Limei Huang

    2017-04-01

    Full Text Available The environmental pollution of 2,4,6-tribromophenol (TBP has attracted attention. Based on an urgent need for the better provision of clean water, in situ determination of TBP is of great importance. Here, a facile and effective approach for detecting TBP is developed, based on coupling molecular imprinting technique with electrodeposition of chitosan (CS on the gold electrode. The TBP imprinting CS film was fabricated by using CS as functional material and TBP as template molecule. The experiments show that the morphologies and electrochemical properties of the imprinted film sensor was different from non-imprinted film electrode. The current of the imprinted film was linearly proportional to the TBP concentration, with a wide linear range of 1.0 × 10−7 mol•L−1 to 1.0 × 10−3 mol•L−1. By selecting drop-coating method as a reference for controlled trials with the same functional material, the results illustrated that the electrodeposition enjoyed a widely linear range advantage.

  5. A facile one-pot preparation of Co3O4/g-C3N4 heterojunctions with excellent electrocatalytic activity for the detection of environmental phenolic hormones

    Science.gov (United States)

    Sun, Yanjuan; Jiang, Jizhou; Liu, Yi; Wu, Shengli; Zou, Jing

    2018-02-01

    The Co3O4/g-C3N4 heterojunctions were prepared by a facile one-pot thermal decomposition technique. Compared with g-C3N4, it was found that Co3O4/g-C3N4 heterojunctions possessed a higher Brunner-Emmet-Teller (BET) surface area, which was beneficial to the diffusion of aim molecules on the electrode surfaces. And the optimal Co3O4/g-C3N4 heterojunctions exhibited a narrower band gap and a higher donor density, resulting in an excellent electrocatalytic activity for environmental phenolic hormones. Moreover, the Co3O4/g-C3N4 heterojunctions were used for the electrochemical sensing of environmental phenolic hormones such as bisphenol A, pentachlorophenol, p-nitrophenol and octylphenol. All detection ranges reached three orders of magnitude, showing a lower limit of detection of 10-9 mol L-1. So, sensitivity and accurate determination of environmental phenolic hormones in real water samples may use this Co3O4/g-C3N4 heterojunctions modified electrode.

  6. First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as e /1000 with the Majorana Demonstrator

    Science.gov (United States)

    Alvis, S. I.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Barton, C. J.; Bertrand, F. E.; Brudanin, V.; Busch, M.; Buuck, M.; Caldwell, T. S.; Chan, Y.-D.; Christofferson, C. D.; Chu, P.-H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Gilliss, T.; Giovanetti, G. K.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Haufe, C. R.; Hehn, L.; Henning, R.; Hoppe, E. W.; Howe, M. A.; Konovalov, S. I.; Kouzes, R. T.; Lopez, A. M.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Myslik, J.; O'Shaughnessy, C.; Othman, G.; Pettus, W.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Reine, A. L.; Rielage, K.; Robertson, R. G. H.; Ruof, N. W.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Varner, R. L.; Vasilyev, S.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C.-H.; Yumatov, V.; Zhitnikov, I.; Zhu, B. X.; Majorana Collaboration

    2018-05-01

    The Majorana Demonstrator is an ultralow-background experiment searching for neutrinoless double-beta decay in 76Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly ionizing particles with an electrical charge less than e are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the Majorana Demonstrator by searching for multiple-detector events with individual-detector energy depositions down to 1 keV. This search is background-free, and no candidate events have been found in 285 days of data taking. New direct-detection limits are set for the flux of lightly ionizing particles for charges as low as e /1000 .

  7. Photoinduced triplet-state electron transfer of platinum porphyrin: a one-step direct method for sensing iodide with an unprecedented detection limit

    KAUST Repository

    Masih, Dilshad

    2015-02-05

    Here, we report for the first time a one-step direct method for sensing halides in aqueous solution using phosphorescence quenching of platinum-cationic porphyrin. This method offers an easy, rapid, environmentally friendly, ultra-sensitive (with a previously unattained detection limit of 1 × 10−12 M) and economical method for the determination of iodide. To fully understand the reaction mechanism responsible for the phosphorescence quenching process, we have employed cutting-edge time-resolved laser spectroscopy with broadband capabilities.

  8. Use of oxidative and reducing vapor generation for reducing the detection limits of iodine in biological samples by inductively coupled plasma atomic emission spectrometry

    International Nuclear Information System (INIS)

    Vtorushina, Eh.A.; Saprykin, A.I.; Knapp, G.

    2009-01-01

    Procedures of microwave combustion in an oxygen flow and microwave acid decomposition of biological samples were optimized for the subsequent determination of iodine. A new method was proposed for the generation of molecular iodine from periodate iona using hydrogen peroxide as a reductant. Procedures were developed for determining iodine in biological samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) using oxidative and reducing vapor generation; these allowed the detection limit for iodine to be lowered by 3-4 orders of magnitude. The developed procedures were used to analyze certified reference materials of milk (Skim Milk Powder BCR 150) and seaweed (Sea Lettuce BCR 279) and a Supradyn vitamin complex

  9. Non-destructive micro-X-ray diffraction analysis of painted artefacts: Determination of detection limits for the chromium oxide-zinc oxide matrix

    International Nuclear Information System (INIS)

    Nel, P.; Lau, D.; Hay, D.; Wright, N.

    2006-01-01

    The development of micro-X-ray diffraction (micro-XRD) enables non-destructive, in situ analysis of crystalline pigments on artworks and archaeological objects. Pigments with X-ray diffraction patterns with large peak intensities may complicate the identification of other components with lower absorption coefficients, especially if present in low concentrations in the paint sample. Investigation of this issue involved: (1) micro-XRD examination and analysis of the amorphous and crystalline phases of fifteen pigment films and (2) micro-XRD examination and semi-quantitative analysis of various chromium oxide-zinc oxide mixtures, which established detection limits as low as 5 ± 2%

  10. Improvement in limit of detection in particle induced X-ray emission by means of rise time and pulse shape discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Papp, Tibor E-mail: tibpapp@netscape.nettibpapp@yahoo.ca; Lakatos, Tamas; Nejedly, Zdenek; Campbell, John L

    2002-04-01

    A digital signal processor, based upon high-rate sampling of the preamplifier output, and equipped with rise time and pulse shape discrimination, has been tested in three situations. This processor provided significant improvement of particle induced X-ray emission and X-ray fluorescence detection limits over the state of the art analog processors, depending on the energy and intensity distribution of the X-ray spectra. Additionally it had a superior performance when measurements were performed in an environment of large electronic noise and in large nuclear background environment. It has also improved the reduction of several artifacts in X-ray spectra.

  11. Detecting position using ARKit II: generating position-time graphs in real-time and further information on limitations of ARKit

    Science.gov (United States)

    Dilek, Ufuk; Erol, Mustafa

    2018-05-01

    ARKit is a framework which allows developers to create augmented reality apps for the iPhone and iPad. In a previous study, we had shown that it could be used to detect position in educational physics experiments and emphasized that the ability to provide position data in real-time was one of the prominent features of this newly emerging technology. In this study, we demonstrate an example of how real-time data acquisition can be employed in educational settings, report some of the limitations of ARKit and how we have overcome these limitations. By means of ARKit or a similar framework, ordinary mobile devices can be adapted for use in microcomputer-based lab activities.

  12. Lower limits of spin detection efficiency for two-parameter two-qubit (TPTQ) states with non-ideal ferromagnetic detectors

    Science.gov (United States)

    Majd, Nayereh; Ghasemi, Zahra

    2016-10-01

    We have investigated a TPTQ state as an input state of a non-ideal ferromagnetic detectors. Minimal spin polarization required to demonstrate spin entanglement according to entanglement witness and CHSH inequality with respect to (w.r.t.) their two free parameters have been found, and we have numerically shown that the entanglement witness is less stringent than the direct tests of Bell's inequality in the form of CHSH in the entangled limits of its free parameters. In addition, the lower limits of spin detection efficiency fulfilling secure cryptographic key against eavesdropping have been derived. Finally, we have considered TPTQ state as an output of spin decoherence channel and the region of ballistic transmission time w.r.t. spin relaxation time and spin dephasing time has been found.

  13. A freeze dried kit formulation for the preparation of 99m Tc labelled human polyclonal IgG for the detection of infection and inflammation

    International Nuclear Information System (INIS)

    Pedraza L, M.

    1996-01-01

    A freeze dried kit formulation for the preparation of 99m Tc-labelled human polyclonal IgG for the detection of infection and inflammation employing direct methods for protein labeling was developed. The method comprises reduction of intrinsic disulphide bridges within the antibody molecule by the use of the reductant 2-mercaptoethanol. Following a subsequent purification, the resulting reduced antibody is labeled via Sn 2+ reduction of pertechnetate in the presence of a weak competing ligand ethane-1-hydroxy-1,1-diphosphonate (EHDP). High labeling efficiencies (>90%) were obtained with high in vitro stability and without effect upon antibody immunoreactivity. Methods of analysis were also established permitting identification of radiochemical impurities which may be present in radiopharmaceutical solution. 99m Tc-polyclonal IgG prepared by the kit method was evaluated for scintigraphic localization of inflammatory lesions and abscesses in rabbits. Data demonstrated that the 99m Tc-polyclonal IgG after kit-reconstitution shows excellent stability and is an effective imaging agent of infection and/or inflammation. (Author)

  14. Evaluation of uncertainty and detection limits in 210Pb and 210Po measurement in water by alpha spectrometry using 210Po spontaneous deposition onto a silver disk

    International Nuclear Information System (INIS)

    Fernández, Pedro L.; Gómez, José; Ródenas, Carmen

    2012-01-01

    An easy and accurate method for the determination of 210 Pb and 210 Po in water using 210 Po spontaneous deposition onto a silver disk is proposed and assessed for its detection capabilities according to the ISO Guide for the expression of uncertainty in measurement (GUM) and ISO Standard 11929-7 concerning the evaluation of the characteristic limits for ionizing radiation measurements. The method makes no assumption on the initial values of the activity concentrations of 210 Pb, 210 Bi and 210 Po in the sample to be analyzed, and is based on the alpha spectrometric measurement of 210 Po in two different aliquots: the first one measured five weeks after the sampling date to ensure radioactive equilibrium between 210 Pb and 210 Bi and the second after a sufficient time for the ingrowth of 210 Po from 210 Pb to be significant. As shown, for a recommended time interval of seven months between 210 Po measurements, the applicability of the proposed method is limited to water samples with a 226 Ra to 210 Pb activity ratio C Ra /C Pb ≤4, as usual in natural waters. Using sample and background counting times of 24 h and 240 h, respectively, the detection limit of the activity concentration of each radionuclide at the sampling time for a 1 L sample typically varies between 0.7 and 16 mBq L −1 for 210 Pb in water samples with an initial activity of 210 Po in the range 0–200 mBq L −1 , and between 0.6 and 8.5 mBq L −1 for 210 Po in water samples with an initial activity of 210 Pb in the same range. - Highlights: ► 210 Pb and 210 Po measurement in water by 210 Po spontaneous deposition onto silver disks. ► 210 Pb and 210 Po determination based on 210 Po measurement in two different aliquots. ► Evaluation of characteristic limits in radioactivity measurements using ISO 11929-7. ► 10 Pb - 210 Po detection limits decrease with time elapsed between 210 Po measurements.

  15. Statistical methods for assays with limits of detection: Serum bile acid as a differentiator between patients with normal colons, adenomas, and colorectal cancer

    Directory of Open Access Journals (Sweden)

    Bonnie LaFleur

    2011-01-01

    Full Text Available In analytic chemistry a detection limit (DL is the lowest measurable amount of an analyte that can be distinguished from a blank; many biomedical measurement technologies exhibit this property. From a statistical perspective, these data present inferential challenges because instead of precise measures, one only has information that the value is somewhere between 0 and the DL (below detection limit, BDL. Substitution of BDL values, with 0 or the DL can lead to biased parameter estimates and a loss of statistical power. Statistical methods that make adjustments when dealing with these types of data, often called left-censored data, are available in many commercial statistical packages. Despite this availability, the use of these methods is still not widespread in biomedical literature. We have reviewed the statistical approaches of dealing with BDL values, and used simulations to examine the performance of the commonly used substitution methods and the most widely available statistical methods. We have illustrated these methods using a study undertaken at the Vanderbilt-Ingram Cancer Center, to examine the serum bile acid levels in patients with colorectal cancer and adenoma. We have found that the modern methods for BDL values identify disease-related differences that are often missed, with statistically naive approaches.

  16. Conducting electrospun fibres with polyanionic grafts as highly selective, label-free, electrochemical biosensor with a low detection limit for non-Hodgkin lymphoma gene.

    Science.gov (United States)

    Kerr-Phillips, Thomas E; Aydemir, Nihan; Chan, Eddie Wai Chi; Barker, David; Malmström, Jenny; Plesse, Cedric; Travas-Sejdic, Jadranka

    2018-02-15

    A highly selective, label-free sensor for the non-Hodgkin lymphoma gene, with an aM detection limit, utilizing electrochemical impedance spectroscopy (EIS) is presented. The sensor consists of a conducting electrospun fibre mat, surface-grafted with poly(acrylic acid) (PAA) brushes and a conducting polymer sensing element with covalently attached oligonucleotide probes. The sensor was fabricated from electrospun NBR rubber, embedded with poly(3,4-ethylenedioxythiophene) (PEDOT), followed by grafting poly(acrylic acid) brushes and then electrochemically polymerizing a conducting polymer monomer with ssDNA probe sequence pre-attached. The resulting non-Hodgkin lymphoma gene sensor showed a detection limit of 1aM (1 × 10 -18 mol/L), more than 400 folds lower compared to a thin-film analogue. The sensor presented extraordinary selectivity, with only 1%, 2.7% and 4.6% of the signal recorded for the fully non-complimentary, T-A and G-C base mismatch oligonucleotide sequences, respectively. We suggest that such greatly enhanced selectivity is due to the presence of negatively charged carboxylic acid moieties from PAA grafts that electrostatically repel the non-complementary and mismatch DNA sequences, overcoming the non-specific binding. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Multielement detection limits and sample nebulization efficiencies of an improved ultrasonic nebulizer and a conventional pneumatic nebulizer in inductively coupled plasma-atomic emission spectrometry

    International Nuclear Information System (INIS)

    Olson, K.W.; Haas, W.J. Jr.; Fassel, V.A.

    1977-01-01

    Two important aspects of the analytical performance of a newly developed ultrasonic nebulizer and a specially designed pneumatic nebulizer have been compared for use in inductively coupled plasma--atomic emission spectroscopy (ICP-AES). The ultrasonic nebulizer, when combined with a conventional aerosol desolvation apparatus, provided an order of magnitude or more improvement in simultaneous multielement detection limits as compared to those obtained when the pneumatic nebulizer was used either with or without desolvation. Application of a novel method for direct measurement of the overall efficiency of nebulization to the two systems showed that an approximately tenfold greater rate of sample delivery to the plasma torch was primarily responsible for the superior detection limits afforded by the ultrasonic nebulizer. A unique feature of the ultrasonic nebulizer described is the protection against chemical attack which is achieved by completely enclosing the transducer in an acoustically coupled borosilicate glass cylinder. Direct sample introduction, convenient sample change, and rapid cleanout are other important characteristics of the system which make it an attractive alternate to pneumatic nebulizer systems

  18. Design of Amperometric Biosensors for the Detection of Glucose Prepared by Immobilization of Glucose Oxidase on Conducting (PolyThiophene Films

    Directory of Open Access Journals (Sweden)

    Maria Pilo

    2018-01-01

    Full Text Available Enzyme-based sensors have emerged as important analytical tools with application in diverse fields, and biosensors for the detection of glucose using the enzyme glucose oxidase have been widely investigated. In this work, the preparation of biosensors by electrochemical polymerization of (polythiophenes, namely 2,2′-bithiophene (2,2′-BT and 4,4′-bis(2-methyl-3-butyn-2-ol-2,2′-bithiophene (4,4′-bBT, followed by immobilization of glucose oxidase on the films, is described. N-cyclohexyl-N′-(2-morpholinoethylcarbodiimide metho-p-toluenesulfonate (CMC was used as a condensing agent, and p-benzoquinone (BQ was used as a redox mediator in solution. The glucose oxidase electrodes with films of 2,2′-BT and 4,4′-bBT were then tested for their ability in detecting glucose from synthetic and real samples (pear, apricot, and peach fruit juices.

  19. Simultaneous quantitative determination of six active components in traditional Chinese medicinal preparation Cerebralcare Granule® by RP-HPLC coupled with diode array detection for quality control.

    Science.gov (United States)

    Wang, Xiang-yang; Ma, Xiao-hui; Li, Wei; Chu, Yang; Guo, Jia-hua; Zhou, Shui-ping; Zhu, Yong-hong

    2014-09-01

    A simple, accurate and reliable method for the simultaneous separation and determination of six active components (protocatechuic acid, chlorogenic acid, caffeic acid, paeoniflorin, ferulic acid and rosmarinic acid) in traditional Chinese medicinal preparation Cerebralcare Granule(®) (CG) was developed using reverse-phase high-performance liquid chromatography coupled with diode array detector detection. The chromatographic separation was performed on a Hypersil GOLD C18 column with aqueous formic acid (0.1%, v/v) and acetonitrile as mobile phase at a flow rate of 0.2 ml/min at 30 °C. Because of the different UV characteristics of these components, change detection wavelength method was used for quantitative analysis. All of the analytes showed good linearity (r > 0.9992). The established method showed good precision and relative standard deviations (%) for intra-day and inter-day variations of 0.15-1.81 and 0.11-1.98%, respectively. The validated method was successfully applied to the simultaneously determination of six active components in CG from different batches. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Ultrahigh sensitivity made simple: nanoplasmonic label-free biosensing with an extremely low limit-of-detection for bacterial and cancer diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S; Svedendahl, M; Kaell, M; Gunnarsson, L; Dmitriev, A, E-mail: alexd@chalmers.s [Department of Applied Physics, Chalmers University of Technology, 41296 Goeteborg (Sweden)

    2009-10-28

    We present a simple and robust scheme for biosensing with an ultralow limit-of-detection down to several pg cm{sup -2} (or several tens of attomoles cm{sup -2}) based on optical label-free biodetection with localized surface plasmon resonances. The scheme utilizes cost-effective optical components and comprises a white light source, a properly functionalized sensor surface enclosed in a simple fluidics chip, and a spectral analyzer. The sensor surface is produced by a bottom-up nanofabrication technique with hole mask colloidal lithography. Despite its simplicity, the method is able to reliably detect protein-protein binding events at low picomolar and femtomolar concentrations, which is exemplified by the label-free detection of the extracellular adherence protein (EAP) found on the outer surface of the bacterium Staphylococcus aureus and of prostate-specific antigen (PSA), which is believed to be a prostate cancer marker. These experiments pave the way towards an ultra-sensitive yet compact biodetection platform for point-of-care diagnostics applications.

  1. ICG-assisted blood vessel detection during stereotactic neurosurgery: simulation study on excitation power limitations due to thermal effects in human brain tissue.

    Science.gov (United States)

    Rühm, Adrian; Göbel, Werner; Sroka, Ronald; Stepp, Herbert

    2014-09-01

    Intraoperative blood vessel detection based on intraluminal indocyanin-green (ICG) would allow to minimize the risk of blood vessel perforation during stereotactic brain tumor biopsy. For a fiber-based approach compatible with clinical conditions, the maximum tolerable excitation light power was derived from simulations of the thermal heat load on the tissue. Using the simulation software LITCIT, the temperature distribution in human brain tissue was calculated as a function of time for realistic single-fiber probes (0.72mm active diameter, numerical aperture 0.35, optional focusing to 0.29mm diameter) and for the optimum ICG excitation wavelength of 785nm. The asymptotic maximum temperature in the simulated tissue region was derived for different radiant fluxes at the distal fiber end. Worst case values were assumed for all other parameters. In addition to homogeneous (normal and tumor) brain tissue with homogeneous blood perfusion, models with localized extra blood vessels incorporated ahead of the distal fiber end were investigated. If one demands that destruction of normal brain tissue must be excluded by limiting the tissue heating to 42°C, then the radiant flux at the distal fiber end must be limited to 33mW with and 43mW without focusing. When considering extra blood vessels of 0.1mm diameter incorporated into homogeneously perfused brain tissue, the tolerable radiant flux is reduced to 22mW with and 32mW without focusing. The threshold value according to legal laser safety regulations for human skin tissue is 28.5mW. For the envisaged modality of blood vessel detection, light power limits for an application-relevant fiber configuration were determined and found to be roughly consistent with present legal regulations for skin tissue. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Detection and quantitation of trace phenolphthalein (in pharmaceutical preparations and in forensic exhibits) by liquid chromatography-tandem mass spectrometry, a sensitive and accurate method.

    Science.gov (United States)

    Sharma, Kakali; Sharma, Shiba P; Lahiri, Sujit C

    2013-01-01

    Phenolphthalein, an acid-base indicator and laxative, is important as a constituent of widely used weight-reducing multicomponent food formulations. Phenolphthalein is an useful reagent in forensic science for the identification of blood stains of suspected victims and for apprehending erring officials accepting bribes in graft or trap cases. The pink-colored alkaline hand washes originating from the phenolphthalein-smeared notes can easily be determined spectrophotometrically. But in many cases, colored solution turns colorless with time, which renders the genuineness of bribe cases doubtful to the judiciary. No method is known till now for the detection and identification of phenolphthalein in colorless forensic exhibits with positive proof. Liquid chromatography-tandem mass spectrometry had been found to be most sensitive, accurate method capable of detection and quantitation of trace phenolphthalein in commercial formulations and colorless forensic exhibits with positive proof. The detection limit of phenolphthalein was found to be 1.66 pg/L or ng/mL, and the calibration curve shows good linearity (r(2) = 0.9974). © 2012 American Academy of Forensic Sciences.

  3. Determination of the detection limit and decision threshold for ionizing radiation measurements. Part 3: Fundamentals and application to counting measurements by high resolution gamma spectrometry, without the influence of sample treatment

    International Nuclear Information System (INIS)

    2000-01-01

    This part of ISO 11929 addresses the field of ionizing radiation measurements in which events (in particular pulses) are counted by high resolution gamma spectrometry registrating a pulse-heights distribution (acquisition of a multichannel spectrum), for example on samples. It considers exclusively the random character of radioactive decay and of pulse counting and ignores all other influences (e.g. arising from sample treatment, weighing, enrichment or the instability of the test setup). It assumes that the distance of neighbouring peaks of gamma lines is not smaller than four times the full width half maximum (FWHM) of gamma line and that the background near to gamma line is nearly a straight line. Otherwise ISO 11929-1 or ISO 11929-2 should be used. ISO 11929 consists of the following parts, under the general title Determination of the detection limit and decision threshold for ionizing radiation measurements: Part 1: Fundamentals and application to counting measurements without the influence of sample treatment; Part 2: Fundamentals and application to counting measurements with the influence of sample treatment; Part 3: Fundamentals and application to counting measurements by high resolution gamma spectrometry, without the influence of sample treatment; Part 4: Fundamentals and application to measurements by use of linear scale analogue ratemeters, without the influence of sample treatment. This part of ISO 11929 was prepared in parallel with other International Standards prepared by WG2 (now WG 17): ISO 11932:1996, Activity measurements of solid materials considered for recycling, re-use or disposal as nonradioactive waste, and ISO 11929-1, ISO 11929-2 and ISO 11929-4, and is, consequently, complementary to these documents

  4. Use of environmental TLD data at a nuclear power station to estimate detection limits for radiation exposure due to station operation

    International Nuclear Information System (INIS)

    Lang, E.; Hardeman, J.; Kahn, B.

    1987-01-01

    The environmental radiation monitoring network maintained by the Georgia Department of Natural Resources at the Hatch Nuclear Plant, Baxley, GA, was used to determine the variability in measured background exposures in order to estimate the detection limits for radiation due to station operation. Data were obtained from LiF thermoluminescent dosimeters (TLDs) exposed in sets of four at 46 locations for 16 consecutive quarters from 1982 to 1985. The average exposure for 695 values was 11.8 microC kg-1 y-1 (mR/quarter). At individual locations, the averages of quarterly exposures ranged from 9.3 to 14.3 microC kg-1 y-1 and had standard deviations from 0.8 to 2.2 microC kg-1 y-1 with a typical standard deviation of 1.5 microC kg-1 y-1. The standard deviation due to reading the TLDs and subtracting the transit plus storage exposure, estimated as 0.4 microC kg-1 y-1, contributed only a small fraction of the uncertainty of the mean background; the greater contribution is from temporal fluctuations. There is a spatial pattern of higher background along the Altamaha River but no distinct seasonal pattern. The observation that exposure values at most locations rose and fell in unison suggested a calculational model that adjusts the average exposure level at a location by an increment determined each quarter at control locations. This model reduced the standard deviation for a predicted quarterly background exposure to 0.9 microC kg-1 y-1, with a range of 0.5 to 1.3 microC kg-1 y-1. If the standard deviation of the net value is multiplied by an error probability constant of 3.3 (type I and II errors not greater than 5%), the detection limits range from 2 to 5 microC kg-1 y-1 at the individual locations, with an average of 3 microC kg-1 y-1. This approach or two similar ones described earlier are recommended for improving the detection limit where needed

  5. Detections and Sensitive Upper Limits for Methane and Related Trace Gases on Mars during 2003-2014, and planned extensions in 2016

    Science.gov (United States)

    Mumma, Michael J.; Villanueva, Geronimo L.; Novak, Robert E.

    2015-11-01

    Five groups report methane detections on Mars; all results suggest local release and high temporal variability [1-7]. Our team searched for CH4 on many dates and seasons and detected it on several dates [1, 9, 10]. TLS (Curiosity rover) reported methane upper limits [6], and then detections [7] that were consistent in size with earlier reports and that also showed rapid modulation of CH4 abundance.[8] argued that absorption features assigned to Mars 12CH4 by [1] might instead be weak lines of terrestrial 13CH4. If not properly removed, terrestrial 13CH4 signatures would appear on the blue wing of terrestrial 12CH4 even when Mars is red-shifted - but they do not (Fig. S6 of [1]), demonstrating that terrestrial signatures were correctly removed. [9] demonstrated that including the dependence of δ13CH4 with altitude did not affect the residual features, nor did taking δ13CH4 as zero. Were δ13CH4 important, its omission would have overemphasized the depth of 13CH4 terrestrial absorption, introducing emission features in the residual spectra [1]. However, the residual features are seen in absorption, establishing their origin as non-terrestrial - [8] now agrees with this view.We later reported results for multiple organic gases (CH4, CH3OH, H2CO, C2H6, C2H2, C2H4), hydroperoxyl (HO2), three nitriles (N2O, NH3, HCN) and two chlorinated species (HCl, CH3Cl) [9]. Most of these species cannot be detected with current space assets, owing to instrumental limitations (e.g., spectral resolving power). However, the high resolution infrared spectrometers (NOMAD, ACS) on ExoMars 2016 (Trace Gas Orbiter) will begin measurements in late 2016. In solar occultation, TGO sensitivities will far exceed prior capabilities.We published detailed hemispheric maps of H2O and HDO on Mars, inferring the size of a lost early ocean [10]. In 2016, we plan to acquire 3-D spatial maps of HDO and H2O with ALMA, and improved maps of organics with iSHELL/NASA-IRTF.References: [1] Mumma et al. Sci09

  6. Electrical impedance scanning as a new imaging modality in breast cancer detection - a short review of clinical value on breast application, limitations and perspectives

    International Nuclear Information System (INIS)

    Malich, A.; Boehm, T.; Facius, M.; Kleinteich, I.; Fleck, M.; Sauner, D.; Anderson, R.; Kaiser, W.A.

    2003-01-01

    Objective. Cancer cells exhibit altered local dielectric properties compared to normal cells, measurable as different electrical conductance and capacitance using electrical impedance scanning (EIS). Therefore, active biocompatible current is applied to the patient for calculation of both parameters taking into account frequency, voltage and current flow. Subjects and methods. 240 women with 280 sonographically and/or mammographically suspicious findings were examined using EIS. All lesions were histologically proven. A lesion was scored as positive, when a focal increased conductance and/or capacitance was measurable using EIS. The lesion was visible as a bright area in a 256 grey-scale computer output. Due to system limitations patients having a pacemaker or pregnant had to be excluded from the study. Results. 91/113 malignant and 108/167 benign lesions were correctly identified using EIS (80.5% sensitivity, 64.7% specificity). NPV and PPV of 83.1% and 60.7% were observed, respectively. Accuracy was 0.73. A wide range of factors can induce false positive results, although by an experienced observer a number of these findings can be detected such as scars, skin alterations, contact artefacts, air bubbles and naevi, hairs and interfering bone. Based upon visibility on ultrasound (194 lesions visible, 86 not visible) significant differences in the detection rate occurred. Histology-dependent detectability rate varied significantly with lowest rate in CIS-cases (50%). Specificity values varied histology-depending, too; probably depending on the rate of proliferation between 75% (inflammatory lesions) and papillomata (50%). Best detectability was observed in malignant lesions with a size between 20 and 30 mm. Further possible applications will be discussed regarding the currently available literature (lymph nodes, salivary glands, mathematical and animal based models). Conclusion. EIS appears to be a promising new additional technology providing a rather high

  7. Natural activity in Hudson River estuary samples and their influence on the detection limits for gamma emitting radionuclides using NaI gamma spectrometry

    International Nuclear Information System (INIS)

    Wrenn, M.E.; Jinks, S.M.; Hairr, L.M.; Paschoa, A.S.; Lentsch, J.W.

    1972-01-01

    Sources of natural radioactivity in Hudson River Estuary are described. The technique of analysis for gamma spectrometry of environmental samples is presented and its pros and cons discussed. The distribution of natural radioactivity in water, biota and sediment was reported as well as the role played by the vertical distribution of cesium-137 in sediments as an indicator of the rate of sedimentation. The effect of the presence of natural radionuclides on the detection limits of man-made nuclides in the Hudson River environment is thoroughly examined. The results obtained with a 4-in. sodium iodide well crystal housed in a low background mercury shielding compare favorably with a more sophisticated Ge(Li) system which uses anticoincidence, as far as the analysis of environmental samples is concerned. (U.S.)

  8. Insight From the Statistics of Nothing: Estimating Limits of Change Detection Using Inferred No-Change Areas in DEM Difference Maps and Application to Landslide Hazard Studies

    Science.gov (United States)

    Haneberg, W. C.

    2017-12-01

    Remote characterization of new landslides or areas of ongoing movement using differences in high resolution digital elevation models (DEMs) created through time, for example before and after major rains or earthquakes, is an attractive proposition. In the case of large catastrophic landslides, changes may be apparent enough that simple subtraction suffices. In other cases, statistical noise can obscure landslide signatures and place practical limits on detection. In ideal cases on land, GPS surveys of representative areas at the time of DEM creation can quantify the inherent errors. In less-than-ideal terrestrial cases and virtually all submarine cases, it may be impractical or impossible to independently estimate the DEM errors. Examining DEM difference statistics for areas reasonably inferred to have no change, however, can provide insight into the limits of detectability. Data from inferred no-change areas of airborne LiDAR DEM difference maps of the 2014 Oso, Washington landslide and landslide-prone colluvium slopes along the Ohio River valley in northern Kentucky, show that DEM difference maps can have non-zero mean and slope dependent error components consistent with published studies of DEM errors. Statistical thresholds derived from DEM difference error and slope data can help to distinguish between DEM differences that are likely real—and which may indicate landsliding—from those that are likely spurious or irrelevant. This presentation describes and compares two different approaches, one based upon a heuristic assumption about the proportion of the study area likely covered by new landslides and another based upon the amount of change necessary to ensure difference at a specified level of probability.

  9. Improved limits and portability over currently employed cadmium monitoring systems through preconcentration for detection by way of micro-/nanofluidic mechanisms

    Science.gov (United States)

    Wach, Paul

    concentrate Cd at an initial concentration of 0.5 mol/m3, which is nearly half the limit of commercially available technology. Additionally, this preconcentration mechanism was demonstrated to potentially advance its capabilities by attaching channels in series or parallel to further preconcentrate for improved detection. Finally, measurement of extremely low concentrations of Cd is possible due to differences seen in the concentration distribution profiles once steady-state is reached.

  10. Solid phase extraction of large volume of water and beverage samples to improve detection limits for GC-MS analysis of bisphenol A and four other bisphenols.

    Science.gov (United States)

    Cao, Xu-Liang; Popovic, Svetlana

    2018-01-01

    Solid phase extraction (SPE) of large volumes of water and beverage products was investigated for the GC-MS analysis of bisphenol A (BPA), bisphenol AF (BPAF), bisphenol F (BPF), bisphenol E (BPE), and bisphenol B (BPB). While absolute recoveries of the method were improved for water and some beverage products (e.g. diet cola, iced tea), breakthrough may also have occurred during SPE of 200 mL of other beverages (e.g. BPF in cola). Improvements in method detection limits were observed with the analysis of large sample volumes for all bisphenols at ppt (pg/g) to sub-ppt levels. This improvement was found to be proportional to sample volumes for water and beverage products with less interferences and noise levels around the analytes. Matrix effects and interferences were observed during SPE of larger volumes (100 and 200 mL) of the beverage products, and affected the accurate analysis of BPF. This improved method was used to analyse bisphenols in various beverage samples, and only BPA was detected, with levels ranging from 0.022 to 0.030 ng/g for products in PET bottles, and 0.085 to 0.32 ng/g for products in cans.

  11. Restriction Cascade Exponential Amplification (RCEA) assay with an attomolar detection limit: a novel, highly specific, isothermal alternative to qPCR.

    Science.gov (United States)

    Ghindilis, Andrey L; Smith, Maria W; Simon, Holly M; Seoudi, Ihab A; Yazvenko, Nina S; Murray, Iain A; Fu, Xiaoqing; Smith, Kenneth; Jen-Jacobson, Linda; Xu, Shuang-Yong

    2015-01-13

    An alternative to qPCR was developed for nucleic acid assays, involving signal rather than target amplification. The new technology, Restriction Cascade Exponential Amplification (RCEA), relies on specific cleavage of probe-target hybrids by restriction endonucleases (REase). Two mutant REases for amplification (Ramp), S17C BamHI and K249C EcoRI, were conjugated to oligonucleotides, and immobilized on a solid surface. The signal generation was based on: (i) hybridization of a target DNA to a Ramp-oligonucleotide probe conjugate, followed by (ii) specific cleavage of the probe-target hybrid using a non-immobilized recognition REase. The amount of Ramp released into solution upon cleavage was proportionate to the DNA target amount. Signal amplification was achieved through catalysis, by the free Ramp, of a restriction cascade containing additional oligonucleotide-conjugated Ramp and horseradish peroxidase (HRP). Colorimetric quantification of free HRP indicated that the RCEA achieved a detection limit of 10 aM (10(-17) M) target concentration, or approximately 200 molecules, comparable to the sensitivity of qPCR-based assays. The RCEA assay had high specificity, it was insensitive to non-specific binding, and detected target sequences in the presence of foreign DNA. RCEA is an inexpensive isothermal assay that allows coupling of the restriction cascade signal amplification with any DNA target of interest.

  12. Quantitative method for the detection and localization of quantum-limited events from radionuclides in cells and tissue sections by computer-enhanced video microscopy

    International Nuclear Information System (INIS)

    Pressman, N.J.; Frost, J.K.; Gupta, P.K.; Showers, R.L.; Gill, G.W.; Cook, D.L.; Frost, J.K. Jr.; Traub, R.K.

    1987-01-01

    Cellular dynamics often involve extremely low concentrat