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Sample records for radiotracer efficiency study

  1. UV-photochemical vapor generation of selenium for atomic absorption spectrometry: Optimization and 75Se radiotracer efficiency study

    NASA Astrophysics Data System (ADS)

    Rybínová, Marcela; Musil, Stanislav; Červený, Václav; Vobecký, Miloslav; Rychlovský, Petr

    2016-09-01

    Volatile selenium compounds were generated UV-photochemically in the continuous flow mode using four UV-photoreactors differing in the material of the reaction coil; Teflon tubing and quartz tubes with various inner diameters and wall thicknesses were tested. Atomic absorption spectrometry with an externally heated quartz furnace atomizer was employed as the detector. The relevant experimental generation parameters were optimized and the basic analytical characteristics were determined. Using formic acid as the photochemical agent, limits of detection achieved for selenium were in the range 46-102 ng L- 1 in dependence on the type of UV-photoreactor employed. When nitric acid was also added to the photochemical agent, the limits of detection were reduced to 27-44 ng L- 1. The repeatability did not exceed 2.4% (5 μg L- 1 Se(IV), n = 10). Experiments with 75Se radiotracer have been performed for the first time to quantify the efficiency of UV-photochemical vapor generation (UV-PVG) of selenium. The highest efficiency of 67 ± 1% was obtained for a UV-photoreactor containing a quartz reaction coil (2.0 mm i.d., 4.0 mm o.d.). The generation efficiency of 61 ± 1% was obtained for a Teflon reaction coil (1.0 mm i.d., 1.4 mm o.d.). Mapping of the radiotracer distribution in the individual parts of the apparatus did not reveal substantial transport losses of the analyte in the UV-PVG system.

  2. Monoamine oxidase: Radiotracer chemistry and human studies

    SciTech Connect

    Fowler, Joanna S.; Logan, Jean; Shumay, Elena; Alia-Klein, Nelly; Wang, Gene-Jack; Volkow, Nora D.

    2015-03-01

    Monoamine oxidase (MAO) oxidizes amines from both endogenous and exogenous sources thereby regulating the concentration of neurotransmitter amines such as serot onin, norepinephrine and dopamine as well as many xenobiotics. MAO inhibitor drugs are used in the treatment of Parkinson’s disease and in depression stimulating the development of radiotracer tools to probe the role of MAO in normal human biology and in disease. Over the past 30 since the first radiotracers were developed and the first PET images of MAO in humans were carried out, PET studies of brain MAO in healthy volunteers and in patients have identified different variables which have contributed to different MAO levels in brain and in peripheral organs. MAO radiotracers and PET have also been used to study the current and developing MAO inhibitor drugs including the selection of doses for clinical trials. In this article, we describe (1) the development of MAO radiotracers; (2) human studies including the relationship of brain MAO levels to genotype, personality, neurological and psychiatric disorders; (3) examples of the use of MAO radiotracers in drug research and development. We will conclude with outstanding needs to improve the radiotracers which are currently used and possible new applications.

  3. Monoamine oxidase: Radiotracer chemistry and human studies

    DOE PAGES

    Fowler, Joanna S.; Logan, Jean; Shumay, Elena; ...

    2015-03-01

    Monoamine oxidase (MAO) oxidizes amines from both endogenous and exogenous sources thereby regulating the concentration of neurotransmitter amines such as serot onin, norepinephrine and dopamine as well as many xenobiotics. MAO inhibitor drugs are used in the treatment of Parkinson’s disease and in depression stimulating the development of radiotracer tools to probe the role of MAO in normal human biology and in disease. Over the past 30 since the first radiotracers were developed and the first PET images of MAO in humans were carried out, PET studies of brain MAO in healthy volunteers and in patients have identified different variablesmore » which have contributed to different MAO levels in brain and in peripheral organs. MAO radiotracers and PET have also been used to study the current and developing MAO inhibitor drugs including the selection of doses for clinical trials. In this article, we describe (1) the development of MAO radiotracers; (2) human studies including the relationship of brain MAO levels to genotype, personality, neurological and psychiatric disorders; (3) examples of the use of MAO radiotracers in drug research and development. We will conclude with outstanding needs to improve the radiotracers which are currently used and possible new applications.« less

  4. Radiotracers for PET and SPECT studies of neurotransmitter systems

    SciTech Connect

    Fowler, J.S.

    1991-01-01

    The study of neurotransmitter systems is one of the major thrusts in emission tomography today. The current generation of Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) radiotracers examines neurotransmitter properties from a number of different perspectives including their pre and post synaptic sites and the activity of the enzymes which regulate their concentration. Although the dopamine system has been the most extensively investigated, other neurotransmitter systems including the acetylcholine muscarine, serotonin, benzodiazepine, opiate, NMDA and others are also under intensive development. Enzymes involved in the synthesis and regulation of neurotransmitter concentration, for example monoamine oxidase and amino acid decarboxylase has also been probed in vivo. Medical applications range from the study of normal function and the characterization of neurotransmitter activity in neurological and psychiatric diseases and in heart disease and cancer to the study of the binding of therapeutic drugs and substances of abuse. This chapter will provide an overview of the current generation of radiotracers for PET and SPECT studies of neurotransmitter systems including radiotracer design, synthesis localization mechanisms and applications in emission tomography. 60 refs., 1 tab.

  5. MONOAMINE OXIDASE: RADIOTRACER DEVELOPMENT AND HUMAN STUDIES.

    SciTech Connect

    FOWLER,J.S.; LOGAN,J.; VOLKOW,N.D.; WANG,G.J.; MACGREGOR,R.R.; DING,Y.S.

    2000-09-28

    PET is uniquely capable of providing information on biochemical transformations in the living human body. Although most of the studies of monoamine oxidase (MAO) have focused on measurements in the brain, the role of peripheral MAO as a phase 1 enzyme for the metabolism of drugs and xenobiotics is gaining attention (Strolin Benedetti and Tipton, 1998; Castagnoli et al., 1997.). MAO is well suited for this role because its concentration in organs such as kidneys, liver and digestive organs is high sometimes exceeding that in the brain. Knowledge of the distribution of the MAO subtypes within different organs and different cells is important in determining which substrates (and which drugs and xenobiotics) have access to which MAO subtypes. The highly variable subtype distribution with different species makes human studies even more important. In addition, the deleterious side effects of combining MAO inhibitors with other drugs and with foodstuffs makes it important to know the MAO inhibitory potency of different drugs both in the brain and in peripheral organs (Ulus et al., 2000). Clearly PET can play a role in answering these questions, in drug research and development and in discovering some of the factors which contribute to the highly variable MAO levels in different individuals.

  6. Preliminary study of the use of radiotracers for leak detection in industrial applications

    NASA Astrophysics Data System (ADS)

    Wetchagarun, S.; Petchrak, A.; Tippayakul, C.

    2015-05-01

    One of the most widespread uses of radiotracers in the industrial applications is the leak detection of the systems. This technique can be applied, for example, to detect leak in heat exchangers or along buried industrial pipelines. The ability to perform online investigation is one of the most important advantages of the radiotracer technique over other non-radioactive leak detection methods. In this paper, a preliminary study of the leak detection using radiotracer in the laboratory scale was presented. Br-82 was selected for this work due to its chemical property, its suitable half-life and its on-site availability. The NH4Br in the form of aqueous solution was injected into the experimental system as the radiotracer. Three NaI detectors were placed along the pipelines to measure system flow rate and to detect the leakage from the piping system. The results obtained from the radiotracer technique were compared to those measured by other methods. It is found that the flow rate obtained from the radiotracer technique agreed well with the one obtained from the flow meter. The leak rate result, however, showed discrepancy between results obtained from two different measuring methods indicating further study on leak detection was required before applying this technique in the industrial system.

  7. Radiotracer Dilution Method for Mercury Inventory Study in Electrolytic Cells

    SciTech Connect

    Sugiharto; Su'ud, Zaki; Kurniadi, Rizal; Waris, Abdul; Santoso, Sigit Budi; Abidin, Zainal; Santoso, Gatot Budi

    2010-06-22

    Purpose of the experiment is to demonstrate feasibility the use of radiotracer to measure weight of mercury in electrolytic cells of soda industry. The weight of mercury in each cell of the plant is designed approximately 1700 kg. Radiotracer is prepared by mixing {sup 203}Hg radioactive mercury with 2400 g of inactive mercury in a bath. The respective precisely weighted mercury aliquots to be injected into the cells are prepared by pouring approximately 130 g of radioactive mercury taken from the bath into 13 standard vials, in accordance with the number of the cells tested. Four standard references prepared by further dilution of {+-}2 g active mercury taken from the bath to obtain the dilution factors range of 12,000 to 20,000 from which the calibration graph is constructed. The injection process is conducting by pouring the radioactive mercury from aliquots into the flowing mercury at the inlet side of the cell and allows them to mix thoroughly. It is assumed that the mass of the radiotracer injected into a closed system remains constant, at least during the period of the test. From this experiment it was observed that the mixing time is two days after injection of radioactive mercury. The inactive mercury in each electrolytic cell calculated by the radiotracer method is of the range 1351.529 kg to 1966.354 kg with maximum error (95% confidence) is 1.52 %. The accuracy of measurement of the present method is better than gravimetric one which accounts 4 % of error on average.

  8. A study of residence time distribution using radiotracer technique in the large scale plant facility

    NASA Astrophysics Data System (ADS)

    Wetchagarun, S.; Tippayakul, C.; Petchrak, A.; Sukrod, K.; Khoonkamjorn, P.

    2017-06-01

    As the demand for troubleshooting of large industrial plants increases, radiotracer techniques, which have capability to provide fast, online and effective detections to plant problems, have been continually developed. One of the good potential applications of the radiotracer for troubleshooting in a process plant is the analysis of Residence Time Distribution (RTD). In this paper, the study of RTD in a large scale plant facility using radiotracer technique was presented. The objective of this work is to gain experience on the RTD analysis using radiotracer technique in a “larger than laboratory” scale plant setup which can be comparable to the real industrial application. The experiment was carried out at the sedimentation tank in the water treatment facility of Thailand Institute of Nuclear Technology (Public Organization). Br-82 was selected to use in this work due to its chemical property, its suitable half-life and its on-site availability. NH4Br in the form of aqueous solution was injected into the system as the radiotracer. Six NaI detectors were placed along the pipelines and at the tank in order to determine the RTD of the system. The RTD and the Mean Residence Time (MRT) of the tank was analysed and calculated from the measured data. The experience and knowledge attained from this study is important for extending this technique to be applied to industrial facilities in the future.

  9. Aquatic live animal radiotracing studies for ecotoxicological applications: Addressing fundamental methodological deficiencies.

    PubMed

    Cresswell, Tom; Metian, Marc; Golding, Lisa A; Wood, Mike D

    2017-06-16

    The use of live animal gamma radioisotope tracer techniques in the field of ecotoxicology allows laboratory studies to accurately monitor contaminant biokinetics in real time for an individual organism. However, methods used in published studies for aquatic organisms are rarely described in sufficient detail to allow for study replication or an assessment of the errors associated with live animal radioanalysis to be identified. We evaluate the influence of some important methodological deficiencies through an overview of the literature on live aquatic animal radiotracer techniques and through the results obtained from our radiotracer studies on four aquatic invertebrate species. The main factors discussed are animal rinsing, radioanalysis and geometry corrections. We provide examples of three main techniques in live aquatic animal radiotracer studies to improve data quality control and demonstrate why each technique is crucial in interpreting the data from such studies. The animal rinsing technique is also relevant to non-radioisotope tracer studies, especially those involving nanoparticles. We present clear guidance on how to perform each technique and explain the importance of proper reporting of the validation of each technique for individual studies. In this paper we describe methods that are often used in lab-based radioecology studies but are rarely described in great detail. We hope that this paper will act as the basis for standard operating procedures for future radioecology studies to improve study replication and data quality control. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  10. Carbon-11 labeling of CP-126,998*: A radiotracer for in vivo studies of acetylcholinesterase

    SciTech Connect

    Musachio, J.L.; Flesher, J.E.; Scheffel, U.

    1996-05-01

    The study of acetylcholinesterase (AChE) via PET is of interest as reduced activity of this enzyme has been observed in Alzheimer`s disease. Our efforts to develop a radiotracer for mapping of AChE have focused on the N-benzylpiperidine benzisoxazole, CP-126,998, a highly potent (IC{sub 50}=0.48 nm) and selective inhibitor of AChE. High specific activity [C-11] CP-126,998 was synthesized (14 - 24% radiochemical yield, non-decay corrected) by treatment of the desmethyl precursor, CP-118,954, with [C-11] methyl iodide and tetrabutylammonium hydroxide in DMF. In vivo studies with [C-11] CP-126,998 in mice show that this radiotracer displays highest uptake in striatum (6.2 %ID/g), a brain region known to be rich in AChE. The (striatum-cerebellum)/cerebellar radioactivity ratio reached a maximum of 4.3 at 30 min postinjection, and this ratio decreased to 2.4 at 120 min. .Radiotracer binding was saturable in vivo by pretreatment with CP-118,954. Pretreatment of mice with diisopropylfluorophosphate (4 mg/kg i.p.), a known AChE inhibitor, significantly inhibited binding in striatum in a dose-dependent manner. Initial results suggest that [C-11] CP-126,998 may prove useful as a marker for the study of AChE in humans via PET.

  11. In vivo distribution of liposome encapsulated hemoglobin studied with imaging radiotracers. Progress report

    SciTech Connect

    Phillips, W.T.

    1992-12-01

    This project has as its objective the development of radiotracer imaging technology to follow the in vivo circulation and organ deposition of liposome encapsulated hemoglobin (LEH). LEH will be labeled with technetium-99m or indium-111 and infused into small animals to monitor any in vivo differences between different LEH formulations. These studies will be correlated with any hematological and pathological changes associated with LEH treatment. Development of such non-invasive monitoring techniques may lead to significant cost effective manufacturing and formulation improvements, and ultimately a more efficacious LEH product. The development of this elegant labeling technique should make it possible to study the effect of various LEH modifications on biodistribution non-invasively in primates and humans.

  12. Chemical speciation and cycling of trace elements in estuaries: radiotracer studies in marine microcosms

    SciTech Connect

    Amdurer, M.

    1983-01-01

    The groups studied include: (1) the ''particle-reactive'' elements Fe(III), (Th), Cr(III), Hg, Sn(IV), Pa, and Be, which had the highest particle distribution coefficients and were removed from the water column most rapidly; (2) the ''recyclable'' elements Mn and Co, which undergo rapid cycling between water column and sediment; (3) the ''biologically-cycled elements'' Ba, Ra, Zn, Cd, Se, As and V, which remained in the water column in soluble form for a significantly longer period than group 1 elements; and (4) the ''quasi-conservative'' elements Cs and Na. A chemical fractionation scheme was developed to further study the probable chemical speciation of these elements in the coastal marine environment by using the added radiotracers as analogs. In summer experiments a high molecular weight (> 10/sup 5/amu) colloidal fraction of the particle-reactive elements developed, but this did not hinder their rapid removal from the water column. Separation of Cr(III) from Cr(VI) allowed calculation of the oxidation rate of Cr(III) in this system; the halftime for oxidation ranged from about two weeks in summer to one month in winter. Strong evidence for uptake of Ba and As by phytoplankton during a bloom was developed. Sediment leaching studies showed that the particle-reactive elements were generally associated with an iron-bearing phase in the sediment. Comparing the concentrations of stable and radioactive Fe, Mn and Zn in various sediment phases showed that, nine months after the radiotracer addition, the tracers were still not equilibrated with their stable counterparts. In this shallow, turbulent, benthos-dominated system the major vector for transfer of the trace elements from the water column to the sediment is resuspended sedimentrary particles; there was little evidence for significant biological transport.

  13. Challenges in the development of dopamine D2- and D3-selective radiotracers for PET imaging studies.

    PubMed

    Mach, Robert H; Luedtke, Robert R

    2017-08-31

    The dopamine D2-like receptors (ie, D2/3 receptors) have been the most extensively studied CNS receptor with Positron Emission Tomography (PET). The 3 different radiotracers that have been used in these studies are [(11) C]raclopride, [(18) F]fallypride, and [(11) C]PHNO. Because these radiotracers have a high affinity for both dopamine D2 and D3 receptors, the density of dopamine receptors in the CNS is reported as the D2/3 binding potential, which reflects a measure of the density of both receptor subtypes. Although the development of D2- and D3-selective PET radiotracers has been an active area of research for many years, this by and large presents an unmet need in the area of translational PET imaging studies. This article discusses some of the challenges that have inhibited progress in this area of research and the current status of the development of subtype selective radiotracers for imaging D3 and D2 dopamine receptors with PET. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Radiotracer study of the preparation of high-purity lanthanum fluoride

    SciTech Connect

    Ewing, K.J.; Jaganathan, J.; Peitersen, L.; Aggarwal, I.D. ); Sommers, J.A.; Fahey, J.V. )

    1992-06-01

    This paper reports that the behavior of the impurities iron, cobalt, yttrium, and cerium is determined via radiotracer techniques for the preparation of high-purity lanthanum fluoride. The behavior of nickel and copper during the coprecipitation of a lanthanum nitrate solution is determined by graphite furnace atomic absorption spectrometric (GFAAS) analysis. There is no commercially available radiotracer for neodymium, a key impurity associated with absorption losses in fluoride glasses. However, the chemical behavior of neodymium and that of yttrium are very similar and, therefore, it is reasonable to assume that the behavior of yttrium throughout the processing is indicative of the behavior of neodymium. The concentrations of impurities in lanthanum nitrate, carbonate, and fluoride are estimated using the radiotracer and GFAAS data for each processing step. Results indicate that while high-purity lanthanum carbonate can be prepared, any impurities present in the lanthanum carbonate will be carried quantitatively into lanthanum fluoride upon hydrofluorination.

  15. Removal of cerium ions from aqueous solution by hydrous ferric oxide--a radiotracer study.

    PubMed

    Dubey, Som Shankar; Rao, Battula Sreenivasa

    2011-02-28

    Radiotracer technique has been used to study the removal behavior of Ce (III) ions from aqueous solutions by synthesized and well characterized hydrous ferric oxide (HFO). Adsorptive concentration (10(-4)-10(-8) mol dm(-3)), pH (ca 4.0-10.0) and temperature (303-333 K) were examined for assessing optimal conditions for removal of these ions. The uptake of Ce (III) ions, which fitted well for Freundlich and D-R isotherms, increased with increase in the temperature and no significant desorption took place in the studied temperature range. The presence of some anions/cations affected the uptake of metal ion markedly. Irradiation of hydrous ferric oxide and tungsten oxide by using a 11.1×10(9) Bq (Ra-Be) neutron source having a neutron flux of 3.9×10(6) cm(-2) s(-1) with associated γ-dose rate of 1.72 Gy/h did not influence the extent of adsorption of Ce (III) significantly. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. In-situ radiotracer and electrochemical study of sulfate accumulation on Al 2024 alloy

    SciTech Connect

    Kolics, A.; Thomas, A.E.; Wieckowski, A.

    1995-12-01

    We have applied radiotracer, electrochemical and ultrahigh vacuum techniques to study sulfate accumulation in passive films on pure aluminum and Al 2024 alloy in 0.1 M NaClO{sub 4} containing 0.1 mM Na{sub 2}SO{sub 4}. We have found that the sulfate coverage is pH and electrode potential dependent and that sulfate is bonded to the surface in two distinctively different ways. While the breakdown of the passive film results in sulfate removal, the subsequent repassivation reintroduces the sulfate anion into the passive film. There is a strong tendency of sulfate to remain in the passive film which explains the inhibitive properties of sulfate in aluminum corrosion. Our data reveal that the anomalous sulfate accumulation during the negative-going polarization can be attributed to the copper content of the alloy surface. The formation of copper-containing nodules determines the electrode potential threshold below which sulfate anions desorb. 20 refs., 4 figs.

  17. A radiotracer study of cerium and manganese uptake onto suspended particles in Chesapeake Bay

    SciTech Connect

    Moffett, J.W. )

    1994-01-01

    The oxidation kinetics of Ce(III) and Mn(II) were studied in Chesapeake Bay in March and July 1990 to establish the role of water column redox processes in contributing to Ce anomalies observed in this estuary (SHOLKOVITZ and ELDERFIELD, 1988; SHOLKOVITZ et al., 1992). Oxidation was measured by adding Mn(II) and Ce(III) to freshly collected water samples as radiotracers and measuring their uptake onto the ambient suspended particle assemblage. Mn(II) oxidation was measured by following the uptake of [sup 54]Mn(II) onto suspended particles and utilizing protocols established by other workers to distinguish oxidation from Mn(II) adsorption. The same protocols were applicable to Ce(III), using [sup 139]Ce(III), and were supported by the use of [sup 152]Eu(III) as a nonredox reactive control. Specific rates of Ce(III) and MN(II) oxidation measured at a station in the North Bay (depth = 4 m) in July were 2016% per day and 4032% per day, respectively. In March, at the same station, the specific rate of Mn(II) of oxidation was only 1-% per day, and Ce(III) oxidation was undetectable. Both Ce(III) and Mn(II) oxidation processes were inhibited by azide, indicating that they were microbially mediated. The seasonal differences probably reflect strong seasonal variation in the abundance of Mn oxidizing bacteria. No Ce(III) oxidation occured in samples collected below the oxic/anoxic interface in July. The specific rates of oxidation for both elements were over 1000 times higher than those measured in the Sargasso Sea. However, the specific rates for Ce(III) and Mn(II) were very similar to each other. This fact, coupled with similar spatial and temporal trends for specific oxidation rates, suggests a common mechanism of oxidation of both elements which may be significant in a wide range of marine environments.

  18. [18F]Fluoro-hydroxyphenethylguanidines: Efficient Synthesis and Comparison of Two Structural Isomers as Radiotracers of Cardiac Sympathetic Innervation.

    PubMed

    Jung, Yong-Woon; Jang, Keun Sam; Gu, Guie; Koeppe, Robert A; Sherman, Phillip S; Quesada, Carole A; Raffel, David M

    2017-03-21

    Fluorine-18 labeled phenethylguanidines are currently under development in our laboratory as radiotracers for quantifying regional cardiac sympathetic nerve density using PET imaging techniques. In this study, we report an efficient synthesis of 18F-hydroxyphenethylguanidines consisting of nucleophilic aromatic [18F]fluorination of a protected diaryliodonium salt precursor followed by a single deprotection step to afford the desired radiolabeled compound. This approach has been shown to reliably produce 4-[18F]fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG, [18F]1) and its structural isomer 3-[18F]fluoro-p-hydroxyphenethylguanidine ([18F]3F-PHPG, [18F]2) with good radiochemical yields. Preclinical evaluations of [18F]2 in non-human primates were performed to compare its imaging properties, metabolism, and myocardial kinetics with those obtained previously with [18F]1. The results of these studies have demonstrated that [18F]2 exhibits imaging properties comparable to those of [18F]1. Myocardial tracer kinetic analysis of each tracer provides quantitative metrics of cardiac sympathetic nerve density. Based on these findings, first-in-human PET studies with [18F]1 and [18F]2 are currently in progress to assess their ability to accurately measure regional cardiac sympathetic denervation in patients with heart disease, with the ultimate goal of selecting a lead compound for further clinical development.

  19. Injected radiotracer techniques in hydrology

    NASA Astrophysics Data System (ADS)

    Rao, S. M.

    1984-08-01

    Radioactive tracers which have several advantages over conventional tracers made significant contributions to the development of the injected tracer method in hydrology. A review of the nuclear and the physico-chemical characteristics of the possible radiotracer compounds leads us to conclude that the most effective groundwater tracers are tritiated water (HTO),82Br- and58Co or60Co as a hexacyanocobaltate complex. A discussion of the various case studies in India and abroad covering the three groups of applications mentioned helps us to conclude that well established radiotracer methods with associated interpretational techniques are available for many short range studies in surface and subsurface hydrology.

  20. A philosophy for CNS radiotracer design.

    PubMed

    Van de Bittner, Genevieve C; Ricq, Emily L; Hooker, Jacob M

    2014-10-21

    to predict bioavailability, blood-brain barrier (BBB) permeability, and the associated issues of nonspecific binding and metabolic stability. To evaluate the synthesized chemical library, researchers need to consider high-throughput affinity assays, the analysis of specific binding, and the importance of fast binding kinetics. Finally, we describe how we initially assess preclinical radiotracer imaging, using brain uptake, specific binding, and preliminary kinetic analysis to identify promising radiotracers that may be useful for human brain imaging. Although we discuss these five design components separately and linearly in this Account, in practice we develop new PET-based radiotracers using these design components nonlinearly and iteratively to develop new compounds in the most efficient way possible.

  1. A philosophy for CNS radiotracer design

    SciTech Connect

    Van de Bittner, Genevieve C.; Ricq, Emily L.; Hooker, Jacob M.

    2014-10-01

    available to predict bioavailability, blood–brain barrier (BBB) permeability, and the associated issues of nonspecific binding and metabolic stability. To evaluate the synthesized chemical library, researchers need to consider high-throughput affinity assays, the analysis of specific binding, and the importance of fast binding kinetics. Lastly, we describe how we initially assess preclinical radiotracer imaging, using brain uptake, specific binding, and preliminary kinetic analysis to identify promising radiotracers that may be useful for human brain imaging. Although we discuss these five design components separately and linearly in this Account, in practice we develop new PET-based radiotracers using these design components nonlinearly and iteratively to develop new compounds in the most efficient way possible.

  2. A philosophy for CNS radiotracer design

    DOE PAGES

    Van de Bittner, Genevieve C.; Ricq, Emily L.; Hooker, Jacob M.

    2014-10-01

    available to predict bioavailability, blood–brain barrier (BBB) permeability, and the associated issues of nonspecific binding and metabolic stability. To evaluate the synthesized chemical library, researchers need to consider high-throughput affinity assays, the analysis of specific binding, and the importance of fast binding kinetics. Lastly, we describe how we initially assess preclinical radiotracer imaging, using brain uptake, specific binding, and preliminary kinetic analysis to identify promising radiotracers that may be useful for human brain imaging. Although we discuss these five design components separately and linearly in this Account, in practice we develop new PET-based radiotracers using these design components nonlinearly and iteratively to develop new compounds in the most efficient way possible.« less

  3. A Philosophy for CNS Radiotracer Design

    PubMed Central

    2015-01-01

    are available to predict bioavailability, blood–brain barrier (BBB) permeability, and the associated issues of nonspecific binding and metabolic stability. To evaluate the synthesized chemical library, researchers need to consider high-throughput affinity assays, the analysis of specific binding, and the importance of fast binding kinetics. Finally, we describe how we initially assess preclinical radiotracer imaging, using brain uptake, specific binding, and preliminary kinetic analysis to identify promising radiotracers that may be useful for human brain imaging. Although we discuss these five design components separately and linearly in this Account, in practice we develop new PET-based radiotracers using these design components nonlinearly and iteratively to develop new compounds in the most efficient way possible. PMID:25272291

  4. Radiotracer method for residence time distribution study in multiphase flow system.

    PubMed

    Sugiharto, S; Su'ud, Z; Kurniadi, R; Wibisono, W; Abidin, Z

    2009-01-01

    [(131)I] isotope in different chemical compounds have been injected into 24in hydrocarbon transmission pipeline containing approximately 95% water, 3% crude oil, 2% gas and negligible solid material, respectively. The system is operated at the temperature around 70 degrees C enabling fluids flow is easier in the pipeline. The segment of measurement was chosen far from the junction point of the pipeline, therefore, it was reasonably to assume that the fluids in such multiphase system were separated distinctively. Expandable tubing of injector was used to ensure that the isotopes were injected at the proper place in the sense that [(131)I]Na isotope was injected into water layer and iodo-benzene, ([131])IC(6)H(5,) was injected into crude oil regime. The radiotracer selection was based on the compatibility of radiotracer with each of fluids under investigation. [(131)I]Na was used for measuring flow of water while iodo-benzene, ([131])IC(6)H(5,) was used for measuring flow of crude oil. Two scintillation detectors were used and they are put at the distances 80 and 100m, respectively, from injection point. The residence time distribution data were utilized for calculation water and crude oil flows. Several injections were conducted in the experiments. Although the crude oil density is lighter than the density of water, the result of measurement shows that the water flow is faster than the crude oil flow. As the system is water-dominated, water may act as carrier and the movement of crude oil is slowed due to friction between crude oil with water and crude oil with gas at top layer. Above of all, this result was able to give answer on the question why crude oil always arrives behind water as it is checked at gathering station. In addition, the flow patterns of the water in the pipeline calculated by Reynolds number and predicted by simple tank-in-series model is turbulence in character.

  5. A radiotracer study on the volatilization and transport effects of thermochemical reagents used in the analysis of alumina powders by slurry electrothermal vaporization inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Peschel, Birgit U.; Herdering, Wilhelm; Broekaert, José A. C.

    2007-02-01

    A neutron-activated Al 2O 3 powder SRM 699 (NIST) containing the γ-radiation emitting radionuclides 51Cr, 59Fe, 60Co and 65Zn has been used to study the influence of thermochemical reagents on the volatilization and transport efficiency for these trace elements in electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) of Al 2O 3 powders. From the signals in the γ-spectra for the radiotracers it has been found that less than 2% of the elements Cr, Fe, Co and Zn is left back in a graphite furnace from Al 2O 3 powders at 2200 °C even without addition of a thermochemical reagent and the latter even was found to decrease the volatilization efficiencies. The recovery for the radiotracers on filters at the end of the transport tube as measured from the signals in the γ-spectra, however, was found to increase in most cases (i.e. from about 10% to more than 20%) when Pd(NO 3) 2, Pd(NO 3) 2 + Mg(NO 3) 2, PdCl 2, IrCl 3, SnCl 2, AgCl, NaF, NH 4Cl and NH 4F were added at amounts generally used in electrothermal vaporization inductively coupled plasma mass spectrometry. However, when adding higher amounts as stoichiometrically required for a complete halogenation of the sample matrix in the case of AgCl, C 8F 15O 2Na, IrCl 3 or PdCl 2 the transport efficiencies considerably decrease again. As shown in the case of NH 4Cl the amount of thermochemical reagent used has to be optimized so as to obtain maximum analyte transport efficiencies. A comparison of the influence of NH 4Cl on the transport efficiencies with its influence on the ETV-ICP-MS signals for Fe demonstrates the importance of transport efficiency changes for the effects of thermochemical reagents in electrothermal vaporization inductively coupled plasma mass spectrometry.

  6. Preclinical Comparative Study of (68)Ga-Labeled DOTA, NOTA, and HBED-CC Chelated Radiotracers for Targeting PSMA.

    PubMed

    Ray Banerjee, Sangeeta; Chen, Zhengping; Pullambhatla, Mrudula; Lisok, Ala; Chen, Jian; Mease, Ronnie C; Pomper, Martin G

    2016-06-15

    (68)Ga-labeled, low-molecular-weight imaging agents that target the prostate-specific membrane antigen (PSMA) are increasingly used clinically to detect prostate and other cancers with positron emission tomography (PET). The goal of this study was to compare the pharmacokinetics of three PSMA-targeted radiotracers: (68)Ga-1, using DOTA-monoamide as the chelating agent; (68)Ga-2, containing the macrocyclic chelating agent p-SCN-Bn-NOTA; and (68)Ga-DKFZ-PSMA-11, currently in clinical trials, which uses the acyclic chelating agent, HBED-CC. The PSMA-targeting scaffold for all three agents utilized a similar Glu-urea-Lys-linker construct. Each radiotracer enabled visualization of PSMA+ PC3 PIP tumor, kidney, and urinary bladder as early as 15 min post-injection using small animal PET/computed tomography (PET/CT). (68)Ga-2 demonstrated the fastest rate of clearance from all tissues in this series and displayed higher uptake in PSMA+ PC3 PIP tumor compared to (68)Ga-1 at 1 h post-injection. There was no significant difference in PSMA+ PC3 PIP tumor uptake for the three agents at 2 and 3 h post-injection. (68)Ga-DKFZ-PSMA-11 demonstrated the highest uptake and retention in normal tissues, including kidney, blood, spleen, and salivary glands and PSMA-negative PC3 flu tumors up to 3 h post-injection. In this preclinical evaluation (68)Ga-2 had the most advantageous characteristics for PSMA-targeted PET imaging.

  7. Novel methodology for the study of mercury methylation and reduction in sediments and water using 197Hg radiotracer.

    PubMed

    Ribeiro Guevara, Sergio; Zizek, Suzana; Repinc, Urska; Pérez Catán, Soledad; Jaćimović, Radojko; Horvat, Milena

    2007-03-01

    Mercury tracers are powerful tools that can be used to study mercury transformations in environmental systems, particularly mercury methylation, demethylation and reduction in sediments and water. However, mercury transformation studies using tracers can be subject to error, especially when used to assess methylation potential. The organic mercury extracted can be as low as 0.01% of the endogenous labeled mercury, and artefacts and contamination present during methylmercury (MeHg) extraction processes can cause interference. Solvent extraction methods based on the use of either KBr/H2SO4 or HCl were evaluated in freshwater sediments using 197Hg radiotracer. Values obtained for the 197Hg tracer in the organic phase were up to 25-fold higher when HCl was used, which is due to the coextraction of 197Hg2+ into the organic phase during MeHg extraction. Evaluations of the production of MeHg gave similar results with both MeHg extraction procedures, but due to the higher Hg2+ contamination of the controls, the uncertainty in the determination was higher when HCl was used. The Hg2+ contamination of controls in the HCl extraction method showed a nonlinear correlation with the humic acid content of sediment pore water. Therefore, use of the KBr/H2SO4 method is recommended, since it is free from these interferences. 197Hg radiotracer (T1/2=2.673 d) has a production rate that is about 50 times higher than that of 203Hg (T1/2=46.595 d), the most frequently used mercury radiotracer. Hence it is possible to obtain a similar level of performance to 203Hg when it is used it in short-term experiments and produced by the irradiation of 196Hg with thermal neutrons, using mercury targets with the natural isotopic composition. However, if the 0.15% natural abundance of the 196Hg isotope is increased, the specific activity of the 197Hg tracer can be significantly improved. In the present work, 197Hg tracer was produced from mercury 51.58% enriched in the 196Hg isotope, and a 340-fold

  8. Synthesis and Preliminary PET Imaging Studies of a FAAH Radiotracer ([¹¹C]MPPO) Based on α-Ketoheterocyclic Scaffold.

    PubMed

    Wang, Lu; Yui, Joji; Wang, Qifan; Zhang, Yiding; Mori, Wakana; Shimoda, Yoko; Fujinaga, Masayuki; Kumata, Katsushi; Yamasaki, Tomoteru; Hatori, Akiko; Rotstein, Benjamin H; Collier, Thomas Lee; Ran, Chongzhao; Vasdev, Neil; Zhang, Ming-Rong; Liang, Steven H

    2016-01-20

    Fatty acid amide hydrolase (FAAH) is one of the principle enzymes for metabolizing endogenous cannabinoid neurotransmitters such as anandamide, and thus regulates endocannabinoid (eCB) signaling. Selective pharmacological blockade of FAAH has emerged as a potential therapy to discern the endogenous functions of anandamide-mediated eCB pathways in anxiety, pain, and addiction. Quantification of FAAH in the living brain by positron emission tomography (PET) would help our understanding of the endocannabinoid system in these conditions. While most FAAH radiotracers operate by an irreversible ("suicide") binding mechanism, a FAAH tracer with reversibility would facilitate quantitative analysis. We have identified and radiolabeled a reversible FAAH inhibitor, 7-(2-[(11)C]methoxyphenyl)-1-(5-(pyridin-2-yl)oxazol-2-yl)heptan-1-one ([(11)C]MPPO) in 13% radiochemical yield (nondecay corrected) with >99% radiochemical purity and 2 Ci/μmol (74 GBq/μmol) specific activity. The tracer showed moderate brain uptake (0.8 SUV) with heterogeneous brain distribution. However, blocking studies with a potent FAAH inhibitor URB597 demonstrated a low to modest specificity to the target. Measurement of lipophilicity, metabolite, and efflux pathway analysis were also performed to study the pharmacokinetic profile of [(11)C]MPPO. In all, we reported an efficient radiolabeling and preliminary evaluation of the first-in-class FAAH inhibitor [(11)C]MPPO with α-ketoheterocyclic scaffold.

  9. Radiotracer study of the adsorption of organic compounds on gold. adsorption of chloroacetic and phenylacetic acid, and the effects of cadmium, copper, and silver adatoms on it

    SciTech Connect

    Horani, G.; Andreev, V.N.; Vazarinov, V.E.

    1986-04-01

    This paper studies the adsorption of monochloroacetic and phenylacetic acid (MA and PA, respectively) by the radiotracer technique on gold-plated gold electrodes in acidic solutions. The authors also study the effect of cadmium, copper, and silver adatoms on these processes. The adsorption of MA was measured as a function of potential of the electrode. Data from these measurements are presented. Data show that cadmium, copper, and silver ions present in the solution have no effect on the adsorption of PA at potentials where they are not adsorbed on the gold surface. It is confirmed that the radiotracer technique will be as effective in adsorption studies on the gold-plated gold electrode as it was in the case of the platinized platinum electrode.

  10. A RADIOTRACER TECHNIQUE FOR ADSORPTION AND CATALYSIS STUDIES: APPLICATION TO {sup 14}C-BENZENE CHEMISORPTION AND REHYDROGENATION ON Pt(111)

    SciTech Connect

    Davis, S. M.; Gordon, B. E.; Press, M.; Somorjai, G. A.

    1981-01-01

    A radiotracer counting system was developed for adsorption and catalysis studies in ultrahigh vacuum using small area, single crystal surfaces. The counting system utilizes a rugged, compact, and rotatable surface barrier detector with a sensitivity sufficient to detect about 1x10{sup 12} molecules containing carbon-14. The operating characteristics and performance of this counting system are discussed along with its application to studies of {sup 14}C-benzene chemisorption and rehydrogenation on the (111) crystal face of platinum.

  11. Radiotracer investigations to study the hydrodynamic characteristics of continuous phase in a pulsed sieve plate extraction column

    NASA Astrophysics Data System (ADS)

    Din, G. U.; Khan, I. H.; Chughtai, I. R.; Inayat, M. H.; Jin, J. H.

    2013-05-01

    The present investigations are focused to study the hydrodynamic characteristics of continuous phase in a pulsed sieve plate extraction column using 68Ga in the form of gallium chloride from an industrial radionuclide generator (68Ge/68Ga). Labeling of water with the subject radiotracer in water-kerosene environment was evaluated. Experiments for Residence Time Distribution (RTD) analysis were carried out for a range of dispersed phase superficial velocities in a liquid-liquid extraction pulsed sieve plate column operating in the emulsion regime with water as continuous and kerosene as dispersed phase. Axial Dispersion Model (ADM) was used to simulate the hydrodynamic characteristics of continuous phase. It has been observed that the axial mixing in the continuous phase decreases and slip velocity increases with increase in superficial velocity of dispersed phase while the holdup of continuous phase was found to decrease with increase in superficial velocity of dispersed phase. ADM with open-open boundary condition was found to be a suitable model for the subject system.

  12. Optimization of integrated impeller mixer via radiotracer experiments.

    PubMed

    Othman, N; Kamarudin, S K; Takriff, M S; Rosli, M I; Engku Chik, E M F; Adnan, M A K

    2014-01-01

    Radiotracer experiments are carried out in order to determine the mean residence time (MRT) as well as percentage of dead zone, V dead (%), in an integrated mixer consisting of Rushton and pitched blade turbine (PBT). Conventionally, optimization was performed by varying one parameter and others were held constant (OFAT) which lead to enormous number of experiments. Thus, in this study, a 4-factor 3-level Taguchi L9 orthogonal array was introduced to obtain an accurate optimization of mixing efficiency with minimal number of experiments. This paper describes the optimal conditions of four process parameters, namely, impeller speed, impeller clearance, type of impeller, and sampling time, in obtaining MRT and V dead (%) using radiotracer experiments. The optimum conditions for the experiments were 100 rpm impeller speed, 50 mm impeller clearance, Type A mixer, and 900 s sampling time to reach optimization.

  13. Optimization of Integrated Impeller Mixer via Radiotracer Experiments

    PubMed Central

    Othman, N.; Kamarudin, S. K.; Takriff, M. S.; Rosli, M. I.; Engku Chik, E. M. F.; Adnan, M. A. K.

    2014-01-01

    Radiotracer experiments are carried out in order to determine the mean residence time (MRT) as well as percentage of dead zone, Vdead (%), in an integrated mixer consisting of Rushton and pitched blade turbine (PBT). Conventionally, optimization was performed by varying one parameter and others were held constant (OFAT) which lead to enormous number of experiments. Thus, in this study, a 4-factor 3-level Taguchi L9 orthogonal array was introduced to obtain an accurate optimization of mixing efficiency with minimal number of experiments. This paper describes the optimal conditions of four process parameters, namely, impeller speed, impeller clearance, type of impeller, and sampling time, in obtaining MRT and Vdead (%) using radiotracer experiments. The optimum conditions for the experiments were 100 rpm impeller speed, 50 mm impeller clearance, Type A mixer, and 900 s sampling time to reach optimization. PMID:24741344

  14. A radiotracer method to study efflux transport of iodide liberated from thyroid hormones via deiodination metabolism in the brain.

    PubMed

    Okamura, Toshimitsu; Igarashi, Jun; Kikuchi, Tatsuya; Fukushi, Kiyoshi; Arano, Yasushi; Irie, Toshiaki

    2009-06-05

    Thyroid hormones (TH) play an important role in the development and functional maintenance of the central nervous system. The purpose of this study was to develop a radiotracer method for studying the in vivo efflux transport of iodide liberated by the TH metabolism in the brain. The rationale of our method is as follows: a radioiodinated compound can enter the brain and rapidly release iodide in situ; the iodide efflux rate can be estimated from the clearance of brain radioactivity after disappearance of the iodinated compound. 6-[(125)I]Iodo-9-pentylpurine ([(125)I]9Pe6IP) was designed to enter the brain and release (125)I(-) by the reaction with glutathione and synthesized from the corresponding bromo derivative in a Br/(125)I exchange reaction. The brain kinetics of radioactivity and radioactive metabolites were investigated after intravenous injection of [(125)I]9Pe6IP into mice. The iodide efflux rate was estimated in mice pretreated with perchlorate, an inhibitor of iodide transport from the brain. High brain uptake (5.3% injected dose/g) was observed at 1 min, and almost complete conversion of [(125)I]9Pe6IP to (125)I(-) occurred 10 min after injection. The (125)I(-) uptake from the blood was negligible. (125)I(-) was eliminated from the brain along a single-exponential curve with a half-life of 6.0 min. Furthermore, dose-dependent inhibition of (125)I(-) efflux was observed in mice pretreated with perchlorate. We conclude that 9Pe6IP labeled with (124)I (positron emitter) or (123)I (single-photon emitter) may be useful for studying the in vivo efflux transport of iodide in the brain using nuclear medicine imaging devices.

  15. The western Mediterranean basin as an aged aerosols reservoir. Insights from an old-fashioned but efficient radiotracer

    NASA Astrophysics Data System (ADS)

    Brattich, E.; Hernández-Ceballos, M. A.; Orza, J. A. G.; Bolívar, J. P.; Tositti, L.

    2016-09-01

    The long-term contemporary 210Pb time series acquired during the period 2004-2011 at two distant sites of different altitude in the Mediterranean basin, El Arenosillo (40 m a.s.l. in southwestern Spain) and Mt. Cimone (2165 m a.s.l. in northern Italy), are analyzed and compared. Besides being considered a tracer of continental air masses, 210Pb radionuclide is also a proxy of fine stable aerosol. For this reason, the measurements of PM10 mass concentrations collected at the same time and the corresponding 210Pb/PM10 ratio at the two sites are considered to gain better insights into the origin and size of the particles. Three statistical trajectory methods are applied to identify and characterize the 210Pb source regions at the two sites. The three methods yield similar outcomes in the source identification, which strengthens the robustness of our results. In addition to the importance of the transport from areas of continental Europe, this study highlights the relevant role of the Mediterranean Sea as a major 210Pb reservoir layer associated to the aged air masses that accumulate in the western Mediterranean basin. The analysis of the sources points out the significant influence of northern Africa to 210Pb increases at both sites as well, even though the most intensive episodes are not of Saharan origin.

  16. Radio-tracer techniques for the study of flow in saturated porous materials

    USGS Publications Warehouse

    Skibitzke, H.E.; Chapman, H.T.; Robinson, G.M.; McCullough, Richard A.

    1961-01-01

    An experiment was conducted by the U.S. Geological Survey to determine the feasibility of using a radioactive substance as a tracer in the study of microscopic flow in a saturated porous solid. A radioactive tracer was chosen in preference to dye or other chemical in order to eliminate effects of the tracer itself on the flow system such as those relating to density, viscosity and surface tension. The porous solid was artificial "sandstone" composed of uniform fine grains of sand bonded together with an epoxy adhesive. The sides of the block thus made were sealed with an epoxy coating compound to insure water-tightness. Because of the chemical inertness of the block it was possible to use radioactive phosphorus (P32). Ion-exchange equilibrium was created between the block and nonradioactive phosphoric acid. Then a tracer tagged with P32 was injected into the block in the desired geometric configuration, in this case, a line source. After equilibrium in isotopic exchange was reached between the block and the line source, the block was rinsed, drained and sawn into slices. It was found that a quantitative analysis of the flow system may be made by assaying the dissected block. ?? 1961.

  17. Bacterial mineralization of phenanthrene on thermally activated palygorskite: A (14)C radiotracer study.

    PubMed

    Biswas, Bhabananda; Sarkar, Binoy; Naidu, Ravi

    2017-02-01

    Clay-bacterial interaction can significantly influence the biodegradation of organic contaminants in the environment. A moderate heat treatment of palygorskite could alter the physicochemical properties of the clay mineral and thus support the growth and function of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria. By using (14)C-labelled phenanthrene and a model bacterium Burkholderia sartisoli, we studied the mineralization of phenanthrene on the surface of a moderately heat-treated (up to 400°C) palygorskite. The heat treatment at 400°C induced a reduction of binding sites (e.g., by the elimination of organic matter and/or channel shrinkage) in the palygorskite and thus imparted a weaker sequestration of phenanthrene on its surface and within the pores. As a result, a supplement with the thermally modified palygorskite (400°C) significantly increased (20-30%; p<0.05) the biomineralization of total phenanthrene in a simulated soil slurry system. These results are highly promising to develop a clay mineral based technology for the bioremediation of PAH contaminants in water and soil environments.

  18. [111In-DOTA]Somatostatin-14 analogs as potential pansomatostatin-like radiotracers - first results of a preclinical study

    PubMed Central

    2012-01-01

    Background In this study, we report on the synthesis, radiolabeling, and biological evaluation of two new somatostatin-14 (SS14) analogs, modified with the universal chelator DOTA. We were interested to investigate if and to what extent such radiotracer prototypes may be useful for targeting sst1-5-expressing tumors in man but, most importantly, to outline potential drawbacks and benefits associated with their use. Methods AT1S and AT2S (DOTA-Ala1-Gly2-c[Cys3-Lys4-Asn5-Phe6-Phe7-Trp8/DTrp8-Lys9-Thr10-Phe11-Thr12-Ser13-Cys14-OH], respectively) were synthesized on the solid support and labeled with 111In. The sst1-5 affinity profile of AT1S/AT2S was determined by receptor autoradiography using [Leu8,dTrp22,125I-Tyr25]SS28 as radioligand. The ability of AT2S to stimulate sst2 or sst3 internalization was qualitatively analyzed by an immunofluorescence-based internalization assay using hsst2- or hsst3-expressing HEK293 cells. Furthermore, the internalization of the radioligands [111In]AT1S and [111In]AT2S was studied at 37 °C in AR4-2J cells endogenously expressing sst2. The in vivo stability of [111In]AT1S and [111In]AT2S was tested by high-performance liquid chromatography analysis of mouse blood collected 5 min after radioligand injection, and biodistribution was studied in normal mice. Selectively for [111In]AT2S, biodistribution was further studied in SCID mice bearing AR4-2J, HEK293-hsst2A+, -hsst3+ or -hsst5+ tumors. Results The new SS14-derived analogs were obtained by solid phase peptide synthesis and were easily labeled with 111In. Both SS14 conjugates, AT1S, and its DTrp8 counterpart, AT2S, showed a pansomatostatin affinity profile with the respective hsst1-5 IC50 values in the lower nanomolar range. In addition, AT2S behaved as an agonist for sst2 and sst3 since it stimulated receptor internalization. The 111In radioligands effectively and specifically internalized into rsst2A-expressing AR4-2J cells with [111In]AT2S internalizing faster than [111In]AT1

  19. Study of axial mixing, holdup and slip velocity of dispersed phase in a pulsed sieve plate extraction column using radiotracer technique.

    PubMed

    Ghiyas Ud Din; Imran Rafiq Chughtai; Hameed Inayat, Mansoor; Hussain Khan, Iqbal

    2009-01-01

    Axial mixing, holdup and slip velocity of dispersed phase which are parameters of fundamental importance in the design and operation of liquid-liquid extraction pulsed sieve plate columns have been investigated. Experiments for residence time distribution (RTD) analysis have been carried out for a range of pulsation frequency and amplitude in a liquid-liquid extraction pulsed sieve plate column with water as dispersed and kerosene as continuous phase using radiotracer technique. The column was operated in emulsion region and (99m)Tc in the form of sodium pertechnetate eluted from a (99)Mo/(99m)Tc generator was used to trace the dispersed phase. Axial dispersed plug flow model with open-open boundary condition and two points measurement method was used to simulate the hydrodynamics of dispersed phase. It has been observed that the axial mixing and holdup of dispersed phase increases with increase in pulsation frequency and amplitude until a maximum value is achieved while slip velocity decreases with increase in pulsation frequency and amplitude until it approaches a minimum value. Short lived and low energy radiotracer (99m)Tc in the form of sodium pertechnetate was found to be a good water tracer to study the hydrodynamics of a liquid-liquid extraction pulsed sieve plate column operating with two immiscible liquids, water and kerosene. Axial dispersed plug flow model with open-open boundary condition was found to be a suitable model to describe the hydrodynamics of dispersed phase in the pulsed sieve plate extraction column.

  20. Model studies using supercritical carbon dioxide fluid (SF CO{sub 2}) as a reaction medium for radiotracer synthesis and purification

    SciTech Connect

    Ferrieri, R.A.; Fowler, J.S.; Wolf, A.P.

    1994-05-01

    Supercritical fluids (SFs) have found widespread use in the analytical field as solvents for compound purification, and initial results on their use for radiotracer synthesis have been reported. SF`s possess the unique feature that their solvating strength can be altered drastically through small changes in pressure and temperature of the fluid within the supercritical regime. We have modified a SF chromatograph to allow us to investigate its use in radiotracer synthesis and purification. The solubility of several PET radiotracers was measured in SF CO{sub 2} at 5000 psi and 55{degrees}C and showed the following: raclopride, 68 {mu}g/mL{sup 2}; (L)-deprenyl, 85 {mu}g/mL; flumazenil, 61 {mu}g/mL; (-)cocaine, 108 {mu}g/mL; ritalin, 45 {mu}g/Ml; and cogentin, 250 {mu}g/mL. Analytical separations were achieved on 30 to 50 {mu}g amounts of (L)-deprenyl (3.9 min RT) and nor-deprenyl (4.7 min RT), as well as raclopride (10.8 min RT) and nor-raclopride (10.3 min RT) using 250 mm x 4.5 mm i.d. Ultracarb 5 ODS (30), and 75 mm x 4.5 mm i.d. silica columns, respectively, and pure SF CO{sub 2} as the mobile phase. Model studies on simple N-alkylation reactions were also carried out using pur SF CO{sub 2} as the reaction medium on a modified alumina support. (L)-Deprenyl was synthesized from only 100 {mu}g of the starting labelling substrate using 500 mg of alumina impregnated with triphenylphosphine diiodide (20% by wt.) and maintained at 170{degrees}C. The methylating agent, methyl iodide, was generated in situ from methanol, but was always present in excess of the substrate. Studies are in progress to reduce methanol amounts. Pressure studies of SF CO{sub 2} ranging from 3000 to 6000 psi showed an 80% increase in the methylation reaction relative to the amount of starting substrate suggesting an effect of the fluid density. Temperature was also a critical parameter here as the reaction did not proceed at 80{degrees}C for similiar pressures.

  1. PET Radiotracers: crossing the blood-brain barrier and surviving metabolism

    PubMed Central

    Pike, Victor W.

    2009-01-01

    Radiotracers for imaging protein targets in living human brain with positron emission tomography (PET) are increasingly useful in clinical research and in drug development. Such radiotracers must fulfill many criteria, among which an ability to enter brain adequately and reversibly without contamination by troublesome radiometabolites is desirable for accurate measurement of the density of a target protein (e.g., neuroreceptor, transporter, enzyme or plaque). Candidate radiotracers may fail as a result of poor passive brain entry, rejection from brain by efflux transporters or undesirable metabolism. These issues are reviewed. Emerging PET radiotracers for measuring efflux transporter function, and new strategies for ameliorating radiotracer metabolism are discussed. A growing understanding of the molecular features affecting the brain penetration, metabolism and efflux transporter sensitivity of prospective radiotracers should ultimately lead to their more rational and efficient design, and also to their greater efficacy. PMID:19616318

  2. Cerenkov Luminescence Imaging as a Modality to Evaluate Antibody-Based PET Radiotracers.

    PubMed

    D'Souza, Jimson W; Hensley, Harvey; Doss, Mohan; Beigarten, Charles; Torgov, Michael; Olafsen, Tove; Yu, Jian Q; Robinson, Matthew K

    2017-01-01

    Antibodies, and engineered antibody fragments, labeled with radioisotopes are being developed as radiotracers for the detection and phenotyping of diseases such as cancer. The development of antibody-based radiotracers requires extensive characterization of their in vitro and in vivo properties, including their ability to target tumors in an antigen-selective manner. In this study, we investigated the use of Cerenkov luminescence imaging (CLI) as compared with PET as a modality for evaluating the in vivo behavior of antibody-based radiotracers.

  3. Synthesis, biological evaluation, and molecular dynamics (MD) simulation studies of three novel F-18 labeled and focal adhesion kinase (FAK) targeted 5-bromo pyrimidines as radiotracers for tumor.

    PubMed

    Fang, Yu; Wang, Dawei; Xu, Xingyu; Liu, Jianping; Wu, Aiqin; Li, Xiang; Xue, Qianqian; Wang, Huan; Wang, Hang; Zhang, Huabei

    2017-02-15

    Focal adhesion kinase (FAK) is considered as an attractive target for oncology. A series of F-18 labeled 5-bromo-N(2)-(4-(2-fluoro-pegylated (FPEG))-3,5-dimethoxyphenyl)-N(4)-(4-methoxyphenyl)pyrimidine-2,4-diamine derivatives were prepared and evaluated as the FAK targeted radiotracers for the early diagnoses of tumor. For the study of the FAK targeted drug molecules, this was the first attempt to develop the tumor diagnostic imaging agents on the radiopharmaceutical level. They inhibited the activity of FAK with IC50 in the range of 91.4-425.7 nM, and among which the result of the [(19)F]2 was relatively good and had a modest IC50 of 91.4 nM. The [(19)F]2 was also profiled in vitro against some other kinds of cancer-related kinases (including two kinds of non-receptor tyrosine kinase: PYK2 and JAK2, and three kinds of receptor tyrosine kinase: IGF-1R, EGFR and PDGFRβ). It displayed 25.2 folds selectivity against PYK2, 35.1 folds selectivity against EGFR, and more than 100 folds selectivity against IGF-1R, JAK2 and PDGFRβ. For the biodistribution in S180 bearing mice, the corresponding [(18)F]2 were also relatively good, with modest tumor uptake of 5.47 ± 0.19 and 5.80 ± 0.06 %ID/g at 15 and 30 min post-injection, respectively. Furthermore, its tumor/muscle, tumor/bone and tumor/blood ratio at 15 min post-injection were 3.16, 2.53 and 4.52, respectively. And its tumor/muscle, tumor/bone and tumor/blood ratio at 30 min post-injection were 3.14, 2.76 and 4.43, respectively. In addition, coronal micro-PET/CT images of a mouse bearing S180 tumor clearly confirmed that [(18)F]2 could be accumulated in tumor, especially at 30 min post-injection. Besides, for the [(18)F]2, both the biodistribution data and the micro-PET/CT imaging study showed significantly reduced uptake of the radiotracer in the tumor tissue at 30 min post-injection in mice that received PF-562,271 (one of the reported best selective FAK inhibitor which was developed by Pfitzer Inc. and

  4. Synthesis and bioevaluation of [18F]4-fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG): a novel radiotracer for quantitative PET studies of cardiac sympathetic innervation

    PubMed Central

    Jang, Keun Sam; Jung, Yong-Woon; Sherman, Phillip S.; Quesada, Carole A.; Gu, Guie; Raffel, David M.

    2013-01-01

    A new cardiac sympathetic nerve imaging agent, [18F]4-fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG), was synthesized and evaluated. The radiosynthetic intermediate [18F]4-fluoro-m-tyramine ([18F]4F-MTA) was prepared and then sequentially reacted with cyanogen bromide and NH4Br/NH4OH to afford [18F]4F-MHPG. Initial bioevaluations of [18F]4F-MHPG (biodistribution studies in rats and kinetic studies in the isolated rat heart) were similar to results previously reported for the carbon-11 labeled analog [11C]4F-MHPG. The neuronal uptake rate of [18F]4F-MHPG into the isolated rat heart was 0.68 ml/min/g wet and its retention time in sympathetic neurons was very long (T1/2 > 13 h). A PET imaging study in a nonhuman primate with [18F]4F-MHPG provided high quality images of the heart, with heart-to-blood ratios at 80–90 min after injection of 5-to-1. These initial kinetic and imaging studies of [18F]4F-MHPG suggest that this radiotracer may allow for more accurate quantification of regional cardiac sympathetic nerve density than is currently possible with existing neuronal imaging agents. PMID:23416009

  5. Radiotracers for PETT: new developments and perspectives

    SciTech Connect

    Fowler, J.S.; Wolf, A.P.

    1983-01-01

    Radiotracer development with positron emitters has its major focus on problems in the neurosciences. Progress is reviewed for high-level isotope production and labelled precurser synthesis with the medical cyclotron. The study of regional brain glucose metabolism represented the first extension of one of the methods of neurochemical autoradiography to humans and the study of brain protein synthesis and neurotransmitter receptors followed. In a more general sense, one PETT instrumentation will provide resolution in the 5 mm range is already emerging. Research status is reviewed. 103 references. (PSB)

  6. The heritage of radiotracers for PET

    SciTech Connect

    Fowler, J.S.; Wolf, A.P.

    1988-05-01

    The history of PET research clearly demonstrates that it is advances in chemistry coupled with a detailed examination of the biochemistry of new radiotracers which has allowed the PET method to be applied to new areas of biology and medicine. Radiotracers whose regional distribution reflects glucose metabolism, neutrotransmitter activity and enzyme activity have all required the development of rapid synthetic methods for the radiotracers themselves and the characterization of their biochemical behavior. This article traces some of the advances in the production of labeled precursors and in radiotracer synthesis and evaluation which have shaped the rapidly expanding application of PET to problems in the neurosciences, in cardiology and in oncology. 54 refs.

  7. The Heritage of Radiotracers for PET

    DOE R&D Accomplishments Database

    Fowler, J. S.; Wolf, A. P.

    1988-05-01

    The history of PET research clearly demonstrates that it is advances in chemistry coupled with a detailed examination of the biochemistry of new radiotracers which has allowed the PET method to be applied to new areas of biology and medicine. Radiotracers whose regional distribution reflects glucose metabolism, neutrotransmitter activity and enzyme activity have all required the development of rapid synthetic methods for the radiotracers themselves and the characterization of their biochemical behavior. This article traces some of the advances in the production of labeled precursors and in radiotracer synthesis and evaluation which have shaped the rapidly expanding application of PET to problems in the neurosciences, in cardiology and in oncology.

  8. Studies on the sorption and desorption characteristics of Zn(II) on the surface soils of nuclear power plant sites in India using a radiotracer technique.

    PubMed

    Dahiya, Sudhir; Shanwal, A V; Hegde, A G

    2005-09-01

    Zinc adsorption was studied in the soils of three nuclear power plant sites of India. 65Zn was used as a radiotracer to study the sorption characteristics of Zn(II). The sorption of zinc was determined at 25 and 45 degrees C at pH 7.8+/-0.2 in the solution of 0.01 M Ca(NO3)2 as supporting electrolyte. The sorption data was tested both in Freundlich and Langmuir isotherms and could be described satisfactorily. The effect of organic matter and other physico-chemical properties on the uptake of zinc was also studied in all the soil samples. The results showed that the cation exchange capacity, organic matter, pH and clay content were the main contributors to zinc sorption in these soils. The adsorption maximum was found to be higher in the soil on Kakarpara Atomic Power Plant sites soils having high organic matter and clay content. The zinc supply parameters of the soils are also discussed. In the desorption studies, the sequential extraction of the adsorbed zinc from soils showed that the diethylene triamine penta acetic acid extracted maximum amount of adsorbed zinc than CaCl2 and Mg(NO3)2. The zinc sorption on the soil and amount of zinc retention after extractants desorption shows a positively correlation with vermiculite and smectite mineral content present in the clay fraction of the soil. The amount desorbed by strong base (NaOH) and demineralised water was almost negligible from soils of all the sites, whereas the desorption by strong acid (HNO3) was 75-96% of the adsorbed zinc.

  9. The Expanding Reach of Environmental Radiotracers - New Chronometers And More Sensitive Measurements

    NASA Astrophysics Data System (ADS)

    Aalseth, C.

    2015-12-01

    Radiotracers in the environment provide powerful tools for understanding environmental processes. Viewed as an age continuum, methods using shorter-lived radionuclides (<100 y) like 3H, 7Be, 85Kr, 134Cs, and 137Cs generally rely on measurements of radioactive decay in samples. Methods using longer-lived radionuclides (>1,000 y) like 10Be, 14C, 36Cl, and 81Kr generally rely on atom-counting measurements such as accelerator mass spectrometry. Significant challenges exist in the age range between 100 and 1,000 years where useful radiotracers are difficult to measure by either method and can have very low abundance. These challenges are being addressed with more sensitive measurements using both atom counting and radioactive decay, extending the reach of established radiotracers as well as adding new chronometers. Improvements in atom-counting methods will be reviewed; the practicality of using 81Kr (abundance ~5×10-13 in atmospheric krypton) for age-dating old aquifers has been established and current work focuses on improving sample utilization efficiency to allow smaller samples to be measured. Better efficiency also brings lower-abundance isotopes within reach, for example 39Ar. Improvements in radioactive decay counting will be reviewed; these take advantage of ultra-pure materials to achieve lower backgrounds and are adding new age-dating reach to the environmental science tool-set with intermediate half-life radionuclides, for example 32Si for sediment cores. These methods also improve sensitivity for established radiotracers like 3H and will allow smaller samples to be measured, allowing specific processes to be traced. For example, using 3H as an indicator of carbon cycling through organic compounds in soil systems. Progress in both atom counting and decay counting is expanding the use of 39Ar for age-dating aquifers, measuring ocean mixing, and age-dating younger glacial ice. Argon-39 is a challenging intermediate-age radiotracer (269-year half-life) with

  10. Principle component analysis for radiotracer signal separation.

    PubMed

    Kasban, H; Arafa, H; Elaraby, S M S

    2016-06-01

    Radiotracers can be used in several industrial applications by injecting the radiotracer into the industrial system and monitoring the radiation using radiation detectors for obtaining signals. These signals are analyzed to obtain indications about what is happening within the system or to determine the problems that may be present in the system. For multi-phase system analysis, more than one radiotracer is used and the result is a mixture of radiotracers signals. The problem is in such cases is how to separate these signals from each other. The paper presents a proposed method based on Principle Component Analysis (PCA) for separating mixed two radiotracer signals from each other. Two different radiotracers (Technetium-99m (Tc(99m)) and Barium-137m (Ba(137m))) were injected into a physical model for simulation of chemical reactor (PMSCR-MK2) for obtaining the radiotracer signals using radiation detectors and Data Acquisition System (DAS). The radiotracer signals are mixed and signal processing steps are performed include background correction and signal de-noising, then applying the signal separation algorithms. Three separation algorithms have been carried out; time domain based separation algorithm, Independent Component Analysis (ICA) based separation algorithm, and Principal Components Analysis (PCA) based separation algorithm. The results proved the superiority of the PCA based separation algorithm to the other based separation algorithm, and PCA based separation algorithm and the signal processing steps gives a considerable improvement of the separation process.

  11. PET Radiotracers of the Cardiovascular System.

    PubMed

    Gropler, Robert J

    2009-01-01

    Cardiovascular PET provides exquisite measurements of key aspects of the cardiovascular system and as a consequence it plays central role in cardiovascular investigation. Moreover, PET is now playing an ever increasing role in the management of the cardiac patient. Central to the success of PET is the development and use of novel radiotracers that permit measurements of key aspects of cardiovascular health such as myocardial perfusion, metabolism, and neuronal function. Moreover, the development of molecular imaging radiotracers is now permitting the interrogation of cellular and sub cellular processes. This article highlights these various radiotracers and their role in both cardiovascular research and potential clinical applications.

  12. Design, synthesis and evaluation of [(3)H]PF-7191, a highly specific nociceptin opioid peptide (NOP) receptor radiotracer for in vivo receptor occupancy (RO) studies.

    PubMed

    Zhang, Lei; Drummond, Elena; Brodney, Michael A; Cianfrogna, Julie; Drozda, Susan E; Grimwood, Sarah; Vanase-Frawley, Michelle A; Villalobos, Anabella

    2014-11-15

    Herein we report the identification of (+)-N-(2-((1H-pyrazol-1-yl)methyl)-3-((1R,3r,5S)-6'-fluoro-8-azaspiro[bicyclo[3.2.1]octane-3,1'-isochroman]-8-yl)propyl)-N-[(3)H]-methylacetamide {[(3)H]PF-7191 [(+)-11]} as a promising radiotracer for the nociceptin opioid peptide (NOP) receptor. (+)-11 demonstrated high NOP binding affinity (Ki = 0.1 nM), excellent selectivity over other opioid receptors (>1000×) and good brain permeability in rats (C(b,u)/C(p,u) = 0.29). Subsequent characterization of [(3)H](+)-11 showed a high level of specific binding and a brain bio-distribution pattern consistent with known NOP receptor expression. Furthermore, the in vivo brain binding of [(3)H](+)-11 in rats was inhibited by a selective NOP receptor antagonist in a dose-responsive manner. This overall favorable profile indicated that [(3)H](+)-11 is a robust radiotracer for pre-clinical in vivo receptor occupancy (RO) measurements and a possible substrate for carbon-11 labeling for positron emission tomography (PET) imaging in higher species. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Radiotracer investigation in a glass production unit.

    PubMed

    Pant, H J; Goswami, Sunil; Biswal, Jayashree; Samantaray, J S; Sharma, V K; Singhal, Sorabh

    2016-10-01

    A radiotracer investigation was carried out in a glass production unit in a glass industry. Lanthanum-140 as lanthanium oxide mixed with silica was used as a radiotracer to trace the molten glass in various sections of the unit. Residence time distributions of molten glass were measured and analyzed to identify the flow abnormities. The flow parameters such as breakthrough time, mean residence time, homogenization time, dead volume and flow patterns in different sections of the unit were obtained from the measured RTD data. The results of the investigation were used to improve and optimize the operation of the glass production unit.

  14. A Mn-54 Radiotracer Study of Mn Isotope Solid-Liquid Exchange during Reductive Transformation of Vernadite (δ-MnO₂) by Aqueous Mn(II)

    SciTech Connect

    Elzinga, Evert J.; Kustka, Adam B.

    2015-04-09

    We employed Mn-54 radiotracers to characterize the extent and dynamics of Mn atom exchange between aqueous Mn(II) and vernadite (δ-Mn(IV)O2) at pH 7.5 under anoxic conditions. Exchange of Mn atoms between the solid and liquid phase is rapid, reaching dynamic equilibrium in 2–4 days. We propose that during the initial stages of reaction, Mn atom exchange occurs through consecutive comproportionation-disproportionation reactions where interfacial electron transfer from adsorbed Mn(II) to lattice Mn(IV) generates labile Mn(III) cations that rapidly disproportionate to reform aqueous Mn(II) and solid-phase Mn(IV). Following nucleation of Mn(III)OOH phases, additional exchange likely occurs through electron transfer from aqueous Mn(II) to solid-phase Mn(III). Our results provide evidence for the fast and extensive production of transient Mn(III) species at the vernadite surface upon contact of this substrate with dissolved Mn(II). We further show that HEPES buffer is a reductant of lattice Mn(IV) in the vernadite structure in our experiments. The methods and results presented here introduce application of Mn-54 tracers as a facile tool to further investigate the formation kinetics of labile Mn(III) surface species and their impacts on Mn-oxide structure and reactivity over a range of environmentally relevant geochemical conditions.

  15. Radiotracer properties determined by high performance liquid chromatography: a potential tool for brain radiotracer discovery.

    PubMed

    Tavares, Adriana Alexandre S; Lewsey, James; Dewar, Deborah; Pimlott, Sally L

    2012-01-01

    Previously, development of novel brain radiotracers has largely relied on simple screening tools. Improved selection methods at the early stages of radiotracer discovery and an increased understanding of the relationships between in vitro physicochemical and in vivo radiotracer properties are needed. We investigated if high performance liquid chromatography (HPLC) methodologies could provide criteria for lead candidate selection by comparing HPLC measurements with radiotracer properties in humans. Ten molecules, previously used as radiotracers in humans, were analysed to obtain the following measures: partition coefficient (Log P); permeability (P(m)); percentage of plasma protein binding (%PPB); and membrane partition coefficient (K(m)). Relationships between brain entry measurements (Log P, P(m) and %PPB) and in vivo brain percentage injected dose (%ID); and K(m) and specific binding in vivo (BP(ND)) were investigated. Log P values obtained using in silico packages and flask methods were compared with Log P values obtained using HPLC. The modelled associations with %ID were stronger for %PPB (r(2)=0.65) and P(m) (r(2)=0.77) than for Log P (r(2)=0.47) while 86% of BP(ND) variance was explained by K(m). Log P values were variable dependant on the methodology used. Log P should not be relied upon as a predictor of blood-brain barrier penetration during brain radiotracer discovery. HPLC measurements of permeability, %PPB and membrane interactions may be potentially useful in predicting in vivo performance and hence allow evaluation and ranking of compound libraries for the selection of lead radiotracer candidates at early stages of radiotracer discovery. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Radiotracer-based strategies to image angiogenesis.

    PubMed

    Haubner, R H; Wester, H J; Weber, W A; Schwaiger, M

    2003-09-01

    Tumour-induced angiogenesis plays an important role in tumour progression. Great efforts are made to develop therapeutic strategies to interfere with this process resulting in the starvation of the tumour. However, strategies to monitor conventional therapies seems to be inappropriate to control these approaches. Thus, there is a keen interest in developing methods supplying information about the corresponding therapeutical effects. Several radiotracer-based approaches focused on different targets in the angiogenic process are currently investigated. One class of tracers is based on matrix metalloproteinases inhibitors. These compounds show promising results in in vitro assays. However, initial data from in vivo studies using murine tumour models could not confirm successful non-invasive monitoring of MMP activity yet. Another strategy uses a radiolabelled single chain fragment against the ED-B domain of fibronectin, an extracellular matrix protein. Promising results demonstrated selective accumulation of the tracer in the tumour vasculature of a murine tumour model. Most of the studies are concentrated on the development of radiolabelled antagonists of the integrin alpha(v)beta(3). This heterodimeric transmembrane glycoprotein is involved in the migration of activated endothelial cells during formation of new vessels. Different compounds have been labelled with (18F), (111)In, (99m)Tc, (90)Y and several iodine isotopes. In in vitro assays most of them revealed high alpha(v)beta(3) affinity and selectivity. Moreover, in different murine tumour models successful non-invasive determination of alpha(v)beta(3) expression has been shown. Some of these approaches indicate that tumour-induced angiogenesis can be monitored in animal studies. Nevertheless, translation of these approaches into clinical settings allowing visualisation of tumour-induced angiogenesis in patients needs still to be demonstrated.

  17. Molecular Imaging of Prostate Cancer: PET Radiotracers

    PubMed Central

    Jadvar, Hossein

    2012-01-01

    OBJECTIVE Recent advances in the fundamental understanding of the complex biology of prostate cancer have provided an increasing number of potential targets for imaging and treatment. The imaging evaluation of prostate cancer needs to be tailored to the various phases of this remarkably heterogeneous disease. CONCLUSION In this article, I review the current state of affairs on a range of PET radiotracers for potential use in the imaging evaluation of men with prostate cancer. PMID:22826388

  18. Alternative approaches for PET radiotracer development in Alzheimer's disease: imaging beyond plaque.

    PubMed

    Holland, Jason P; Liang, Steven H; Rotstein, Benjamin H; Collier, Thomas L; Stephenson, Nickeisha A; Greguric, Ivan; Vasdev, Neil

    2014-04-01

    Alzheimer's disease (AD) and related dementias show increasing clinical prevalence, yet our understanding of the etiology and pathobiology of disease-related neurodegeneration remains limited. In this regard, noninvasive imaging with radiotracers for positron emission tomography (PET) presents a unique tool for quantifying spatial and temporal changes in characteristic biological markers of brain disease and for assessing potential drug efficacy. PET radiotracers targeting different protein markers are being developed to address questions pertaining to the molecular and/or genetic heterogeneity of AD and related dementias. For example, radiotracers including [(11) C]-PiB and [(18) F]-AV-45 (Florbetapir) are being used to measure the density of Aβ-plaques in AD patients and to interrogate the biological mechanisms of disease initiation and progression. Our focus is on the development of novel PET imaging agents, targeting proteins beyond Aβ-plaques, which can be used to investigate the broader mechanism of AD pathogenesis. Here, we present the chemical basis of various radiotracers which show promise in preclinical or clinical studies for use in evaluating the phenotypic or biochemical characteristics of AD. Radiotracers for PET imaging neuroinflammation, metal ion association with Aβ-plaques, tau protein, cholinergic and cannabinoid receptors, and enzymes including glycogen-synthase kinase-3β and monoamine oxidase B amongst others, and their connection to AD are highlighted.

  19. Current status of positron emission tomography radiotracers for serotonin receptors in humans.

    PubMed

    Zimmer, Luc; Le Bars, Didier

    2013-01-01

    Serotonin (5-HT) neurotransmission plays a key modulatory role in the brain. This system is critical for pathophysiological processes and many drug treatments for brain disorders interact with its 14 subtypes of receptors. Positron emission tomography (PET) is a unique tool for the study of the living brain in translational studies from animal models to patients in neurology or psychiatry. This short review is intended to cover the current status of PET radioligands used for imaging human brain 5-HT receptors. Here, we describe the available PET radioligands for the 5-HT1A , 5-HT1B , 5-HT2A , 5-HT4 and 5-HT6 receptors. Finally, we highlight the future challenges for a functional PET imaging of serotonin receptors, including the research towards specific PET radiotracers for yet unexplored serotonin receptors, the need of radiotracers for endogenous serotonin level measurement and the contribution of agonist radiotracers for functional imaging of 5-HT neurotransmission.

  20. A method based on Monte Carlo simulations and voxelized anatomical atlases to evaluate and correct uncertainties on radiotracer accumulation quantitation in beta microprobe studies in the rat brain

    NASA Astrophysics Data System (ADS)

    Pain, F.; Dhenain, M.; Gurden, H.; Routier, A. L.; Lefebvre, F.; Mastrippolito, R.; Lanièce, P.

    2008-10-01

    The β-microprobe is a simple and versatile technique complementary to small animal positron emission tomography (PET). It relies on local measurements of the concentration of positron-labeled molecules. So far, it has been successfully used in anesthetized rats for pharmacokinetics experiments and for the study of brain energetic metabolism. However, the ability of the technique to provide accurate quantitative measurements using 18F, 11C and 15O tracers is likely to suffer from the contribution of 511 keV gamma rays background to the signal and from the contribution of positrons from brain loci surrounding the locus of interest. The aim of the present paper is to provide a method of evaluating several parameters, which are supposed to affect the quantification of recordings performed in vivo with this methodology. We have developed realistic voxelized phantoms of the rat whole body and brain, and used them as input geometries for Monte Carlo simulations of previous β-microprobe reports. In the context of realistic experiments (binding of 11C-Raclopride to D2 dopaminergic receptors in the striatum; local glucose metabolic rate measurement with 18F-FDG and H2O15 blood flow measurements in the somatosensory cortex), we have calculated the detection efficiencies and corresponding contribution of 511 keV gammas from peripheral organs accumulation. We confirmed that the 511 keV gammas background does not impair quantification. To evaluate the contribution of positrons from adjacent structures, we have developed β-Assistant, a program based on a rat brain voxelized atlas and matrices of local detection efficiencies calculated by Monte Carlo simulations for several probe geometries. This program was used to calculate the 'apparent sensitivity' of the probe for each brain structure included in the detection volume. For a given localization of a probe within the brain, this allows us to quantify the different sources of beta signal. Finally, since stereotaxic accuracy is

  1. Radiotracer Imaging of Sediment Columns

    NASA Astrophysics Data System (ADS)

    Moses, W. W.; O'Neil, J. P.; Boutchko, R.; Nico, P. S.; Druhan, J. L.; Vandehey, N. T.

    2010-12-01

    Nuclear medical PET and SPECT cameras routinely image radioactivity concentration of gamma ray emitting isotopes (PET - 511 keV; SPECT - 75-300 keV). We have used nuclear medical imaging technology to study contaminant transport in sediment columns. Specifically, we use Tc-99m (T1/2 = 6 h, Eγ = 140 keV) and a SPECT camera to image the bacteria mediated reduction of pertechnetate, [Tc(VII)O4]- + Fe(II) → Tc(IV)O2 + Fe(III). A 45 mL bolus of Tc-99m (32 mCi) labeled sodium pertechnetate was infused into a column (35cm x 10cm Ø) containing uranium-contaminated subsurface sediment from the Rifle, CO site. A flow rate of 1.25 ml/min of artificial groundwater was maintained in the column. Using a GE Millennium VG camera, we imaged the column for 12 hours, acquiring 44 frames. As the microbes in the sediment were inactive, we expected most of the iron to be Fe(III). The images were consistent with this hypothesis, and the Tc-99m pertechnetate acted like a conservative tracer. Virtually no binding of the Tc-99m was observed, and while the bolus of activity propagated fairly uniformly through the column, some inhomogeneity attributed to sediment packing was observed. We expect that after augmentation by acetate, the bacteria will metabolically reduce Fe(III) to Fe(II), leading to significant Tc-99m binding. Imaging sediment columns using nuclear medicine techniques has many attractive features. Trace quantities of the radiolabeled compounds are used (micro- to nano- molar) and the half-lives of many of these tracers are short (<1 day). This allows multiple measurements to be made on the same column and thus the sediment biology to be monitored non-invasively over time (i.e. after an augmentation has been introduced) and minimizes long-lived radioactive waste. Different parameters can be measured, depending on the tracer type and delivery. A constant infusion of a conservative tracer, such as the positron emitter Br-76 (T1/2= 16.2 hr), measures the exclusion fraction (as

  2. Fluorine-18 patents (2009–2015). Part 1: novel radiotracers

    PubMed Central

    Brooks, Allen F; Drake, Lindsey R; Stewart, Megan N; Cary, Brian P; Jackson, Isaac M; Mallette, Dale; Mossine, Andrew V; Scott, Peter JH

    2016-01-01

    The most commonly utilized PET radionuclide is fluorine-18 (18F) because of its convenient half-life and excellent imaging properties. In this review, we present the first analysis of patents issued for radiotracers labeled with fluorine-18 (between 2009 and 2015), and provide perspective on current trends and future directions in PET radiotracer development. PMID:26670619

  3. Further evaluation of [11C]MP-10 as a radiotracer for phosphodiesterase 10A (PDE10A): PET imaging study in rhesus monkeys and brain tissue metabolite analysis

    PubMed Central

    Lin, Shu-fei; Labaree, David; Chen, Ming-Kai; Holden, Daniel; Gallezot, Jean-Dominique; Kapinos, Michael; Teng, Jo-Ku; Najafzadeh, Soheila; Plisson, Christophe; Rabiner, Eugenii A.; Gunn, Roger N.; Carson, Richard E.; Huang, Yiyun

    2014-01-01

    [11C]MP-10 is a potent and specific PET tracer previously shown to be suitable for imaging the PDE10A in baboons with reversible kinetics and high specific binding. However, another report indicated that [11C]MP-10 displayed seemingly irreversible kinetics in rhesus monkeys, potentially due to the presence of a radiolabeled metabolite capable of penetrating the blood-brain-barrier (BBB) into the brain. This study was designed to address the discrepancies between the species by re-evaluating [11C]MP-10 in vivo in rhesus monkey with baseline scans to assess tissue uptake kinetics and self-blocking scans with unlabeled MP-10 to determine binding specificity. Ex vivo studies with one rhesus monkey and 4 Sprague-Dawley rats were also performed to investigate the presence of radiolabeled metabolites in the brain. Our results indicated that [11C]MP-10 displayed reversible uptake kinetics in rhesus monkeys, albeit slower than in baboons. Administration of unlabeled MP-10 reduced the binding of [11C]MP-10 in a dose-dependent manner in all brain regions including the cerebellum. Consequently, the cerebellum appeared not to be a suitable reference tissue in rhesus monkeys. Regional volume of distribution (VT) was mostly reliably derived with the multilinear analysis (MA1) method. In ex vivo studies in the monkey and rats only negligible (< 2.7%) amount of radiometabolites was seen in the brain of either species. In summary, results from the present study strongly support the suitability of [11C]MP-10 as a radiotracer for PET imaging and quantification of PDE10A in non-human primates. PMID:25450608

  4. Bioaccumulation of (63)Ni in the scleractinian coral Stylophora pistillata and isolated Symbiodinium using radiotracer techniques.

    PubMed

    Hédouin, Laetitia; Metian, Marc; Teyssié, Jean-Louis; Oberhänsli, François; Ferrier-Pagès, Christine; Warnau, Michel

    2016-08-01

    Development of nickel mining activities along the New Caledonia coasts threatens the biodiversity of coral reefs. Although the validation of tropical marine organisms as bioindicators of metal mining contamination has received much attention in the literature over the last decade, few studies have examined the potential of corals, the fundamental organisms of coral reefs, to monitor nickel (Ni) contamination in tropical marine ecosystems. In an effort to bridge this gap, the present work investigated the bioaccumulation of (63)Ni in the scleractinian coral Stylophora pistillata and in its isolated zooxanthellae Symbiodinium, using radiotracer techniques. Results highlight the high capacities of coral tissues (zooxanthellae and host tissues) to efficiently bioconcentrate (63)Ni compared to skeleton (Concentration Factors CF at 14 days of exposure are 3 orders of magnitude higher in tissues than in skeleton). When non-contaminated conditions were restored, (63)Ni was more efficiently retained in skeleton than in coral tissues, with biological half-lives (Tb½) of 44.3 and 6.5 days, respectively. In addition, our work showed that Symbiodinium bioconcentrated (63)Ni exponentially, with a vol/vol concentration factor at steady state (VCFSS) reaching 14,056. However, compilation of our results highlighted that despite efficient bioconcentration of (63)Ni in Symbiodinium, their contribution to the whole (63)Ni accumulation in coral nubbins represents less than 7%, suggesting that other biologically controlled processes occur in coral host allowing such efficient bioconcentration in coral tissues. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Preclinical acute toxicity studies and rodent-based dosimetry estimates of the novel sigma-1 receptor radiotracer [(18)F]FPS.

    PubMed

    Waterhouse, Rikki N; Stabin, Michael G; Page, John G

    2003-07-01

    [(18)F]1-(Fluoropropyl)-4-[(4-cyanophenoxy)methyl]piperidine ([(18)F]FPS) is a novel high affinity (KD = 0.5 nM) sigma receptor radioligand that exhibits saturable and selective in vivo binding to sigma receptors in rats, mice and non-human primates. In order to support an IND application for the characterization of [(18)F]FPS through PET imaging studies in humans, single organ and whole body radiation adsorbed doses associated with [(18)F]FPS injection were estimated from distribution data obtained in rats. In addition, acute toxicity studies were conducted in rats and rabbits and limited toxicity analyses were performed in dogs. Radiation dosimetry estimates obtained using rat biodistribution analysis of [(18)F]FPS suggest that most organs would receive around 0.012-0.015 mGy/MBq. The adrenal glands, brain, kidneys, lungs, and spleen would receive slightly higher doses (0.02-0.03 mGy/MBq). The adrenal glands were identified as the organs receiving the greatest adsorbed radiation dose. The total exposure resulting from a 5 mCi administration of [(18)F]FPS is well below the FDA defined limits for yearly cumulative and per study exposures to research participants. Extended acute toxicity studies in rats and rabbits, and limited acute toxicity studies in beagle dogs suggest at least a 175-fold safety margin in humans at a mass dose limit of 2.8 microg per intravenous injection. This estimate is based on the measured no observable effect doses (in mg/m(2)) in these species. These data support the expectation that [(18)F]FPS will be safe for use in human PET imaging studies at a maximum administration of 5 mCi and a mass dose equal to or less than 2.8 microg FPS per injection.

  6. PET Imaging of D2/3 agonist binding in healthy human subjects with the radiotracer [11C]-N-propyl-nor-apomorphine (NPA): preliminary evaluation and reproducibility studies

    PubMed Central

    Narendran, Rajesh; Frankle, W. Gordon; Mason, N. Scott; Laymon, Charles M.; Lopresti, Brian J; Price, Julie C.; Kendro, Steve; Vora, Shivangi; Litschge, Maralee; Mountz, James M.; Mathis, Chester A.

    2009-01-01

    Objective (-)-N-[11C]-Propyl-norapomorphine (NPA) is a full dopamine D2/3 receptor agonist radiotracer suitable for imaging D2/3 receptors configured in a state of high affinity for agonists using Positron Emission Tomography (PET). The aim of the present study was to define the optimal analytic method to derive accurate and reliable D2/3 receptor parameters with [11C]NPA. Methods Six healthy subjects (4 females/2 males) underwent two [11C]NPA scans in the same day. D2/3 receptor binding parameters were estimated using kinetic analysis (using 1- and 2- tissue compartment models) as well as simplified reference tissue method in the three functional subdivisions of the striatum (associative striatum, AST; limbic striatum LST and sensorimotor striatum SMST). The test-retest variability and intraclass correlation coefficient were assessed for distribution volume (VT), binding potential relative to plasma concentration (BPP), and binding potential relative to nondisplaceable uptake (BPND) Results A two-tissue compartment kinetic model adequately described the functional subdivisions of the striatum as well as cerebellum time-activity data. The reproducibility of VT was excellent (≤ 10%) in all regions, for this approach. The reproducibility of both BPP (≤ 12%) and BPND (≤ 10%) was also excellent. The intraclass correlation coefficient of BPP and BPND were acceptable as well (> 0.75) in the three functional subdivisions of the striatum. Although SRTM led to an underestimation of BPND values relative to that estimated by kinetic analysis by 8 to 13%, the values derived using both the methods were reasonably well correlated (r2 = 0.89, n = 84). Both methods were similarly effective at detecting the differences in [11C]NPA BPND between subjects. Conclusion The results of this study indicate that [11C]NPA can be used to measure D2/3 receptors configured in a state of high affinity for the agonists with high reliability and reproducibility in the functional subdivisions

  7. Radiotracer Technology in Mixing Processes for Industrial Applications

    PubMed Central

    Othman, N.; Kamarudin, S. K.

    2014-01-01

    Many problems associated with the mixing process remain unsolved and result in poor mixing performance. The residence time distribution (RTD) and the mixing time are the most important parameters that determine the homogenisation that is achieved in the mixing vessel and are discussed in detail in this paper. In addition, this paper reviews the current problems associated with conventional tracers, mathematical models, and computational fluid dynamics simulations involved in radiotracer experiments and hybrid of radiotracer. PMID:24616642

  8. Exploring the transport of plant metabolites using positron emitting radiotracers

    PubMed Central

    Kiser, Matthew R.; Reid, Chantal D.; Crowell, Alexander S.; Phillips, Richard P.; Howell, Calvin R.

    2008-01-01

    Short-lived positron-emitting radiotracer techniques provide time-dependent data that are critical for developing models of metabolite transport and resource distribution in plants and their microenvironments. Until recently these techniques were applied to measure radiotracer accumulation in coarse regions along transport pathways. The recent application of positron emission tomography (PET) techniques to plant research allows for detailed quantification of real-time metabolite dynamics on previously unexplored spatial scales. PET provides dynamic information with millimeter-scale resolution on labeled carbon, nitrogen, and water transport over a small plant-size field of view. Because details at the millimeter scale may not be required for all regions of interest, hybrid detection systems that combine high-resolution imaging with other radiotracer counting technologies offer the versatility needed to pursue wide-ranging plant physiological and ecological research. In this perspective we describe a recently developed hybrid detection system at Duke University that provides researchers with the flexibility required to carry out measurements of the dynamic responses of whole plants to environmental change using short-lived radiotracers. Following a brief historical development of radiotracer applications to plant research, the role of radiotracers is presented in the context of various applications at the leaf to the whole-plant level that integrates cellular and subcellular signals and∕or controls. PMID:19404430

  9. Radiotracer investigations in aniline production reactors.

    PubMed

    Pant, H J; Yelgoankar, V N

    2002-09-01

    Radiotracer investigations were carried out to measure the residence time distribution (RTD) of the heat transfer medium (HTM) in two identical aniline production reactors. One was operating abnormally while the other functioned normally. Investigations were carried out to identify the cause(s) of inadequate heat transfer from the tube-side to the shell-side of the abnormally operating reactor. For measuring the RTD of the HTM in the shell-side of the reactor. 82Br as paradibromobenzene was used as a tracer. The analysis of the measured RTD data revealed that about 60% of the shell-side volume of the abnormally operating reactor was fouled/dead, this being the root cause of the inadequate heat transfer. The modelling of RTD data indicated undesired parallel flow streams in the shell-side of the abnormal reactor. Shutdown of the abnormally operating reactor was instituted to allow remediation, fouling subsequently being visibly confirmed. The planned shutdown resulted in reduction in downtime, with substantial economic benefit to the industry.

  10. Long-Circulating and pH-Sensitive Liposome Preparation Trapping a Radiotracer for Inflammation Site Detection.

    PubMed

    Mota, Luciene Das Graças; de Barros, André Luís Branco; Fuscaldi, Leonardo Lima; de Oliveira, Mônica Cristina; Cardoso, Valbert Nascimento

    2015-06-01

    Inflammatory and infectious diseases are one of the most common causes of mortality and morbidity. This paper aimed to prepare and to evaluate the ability of long-circulating and pH-sensitive liposomes, trapping a radiotracer, to identify inflamed focus. The physicochemical characterization of freeze-dried liposomes, using glucose as cryoprotectant, showed 80% of the vesicles with adequate mean diameter and good vesicle size homogeneity. Radiotracer encapsulation percentage in liposomes was 10.65%, of which 4.88% was adsorbed on the surface of the vesicles. Furthermore, liposomes presented positive zeta potential. Freeze-dried liposomes, stored for 180 days at 4 degrees C, did not show significant changes in the mean diameter, indicating good stability. Free radiotracer and radiolabeled liposomes were injected into inflammation focus-bearing rats, and ex-vivo biodistribution studies and scintigraphic images were performed. Results showed that radiopharmaceutical, free and encapsulated into liposomes, were able to identify the inflamed site. Target/non-target ratios, obtained by scintigraphic images, were greater than 1.5 at all investigated times. Data did not show significant differences between the free radiotracer and radiolabeled liposomes. Results suggest that this liposomal preparation could be employed as an alternative procedure for inflamed site detection by means of scintigraphic images. However, as the radiotracer is adsorbed onto the liposome surface by electrostatic forces, it is suggested that a neutral radiopharmaceutical be used to confirm the potential of this formulation as a scintigraphic probe for inflammation/infection detection.

  11. Cerenkov Luminescence Imaging as a Modality to Evaluate Antibody-Based PET Radiotracers

    PubMed Central

    D’Souza, Jimson W.; Hensley, Harvey; Doss, Mohan; Beigarten, Charles; Torgov, Michael; Olafsen, Tove; Yu, Jian Q.

    2017-01-01

    Antibodies, and engineered antibody fragments, labeled with radioisotopes are being developed as radiotracers for the detection and phenotyping of diseases such as cancer. The development of antibody-based radiotracers requires extensive characterization of their in vitro and in vivo properties, including their ability to target tumors in an antigen-selective manner. In this study, we investigated the use of Cerenkov luminescence imaging (CLI) as compared with PET as a modality for evaluating the in vivo behavior of antibody-based radiotracers. Methods: The anti–prostate-specific membrane antigen (PSMA) huJ591 antibody (IgG; 150 kDa) and its minibody (Mb; 80 kDa) format were functionalized with the chelator 1,4,7-triazacyclononane-1-glutaric acid-4,7-diacetic acid (NODAGA) and radiolabeled with the positron-emitting radionuclide 64Cu (half-life, 12.7 h). Immunoreactive preparations of the radiolabeled antibodies were injected into NCr nu/nu mice harboring PSMA-positive CWR22Rv1 and PSMA-negative PC-3 tumor xenografts. Tumor targeting was evaluated by both PET and CLI. Results: 64Cu-NODAGA-PSMA-IgG and 64Cu-NODAGA-PSMA-Mb retained the ability to bind cell surface PSMA, and both radiotracers exhibited selective uptake into PSMA-positive tumors. Under the experimental conditions used, PSMA-selective uptake of 64Cu-NODAGA-PSMA-IgG and 64Cu-NODAGA-PSMA-Mb was observed by CLI as early as 3 h after injection, with tumor-to-background ratios peaking at 24 (IgG) and 16 (Mb) h after injection. Targeting data generated by CLI correlated with that generated by PET and necropsy. Conclusion: CLI provided a rapid and simple assessment of the targeting specificity and pharmacokinetics of the antibody-based PET radiotracers that correlated well with the behavior observed by standard PET imaging. Moreover, CLI provided clear discrimination between uptake kinetics of an intact IgG and its small-molecular-weight derivative Mb. These data support the use of CLI for the evaluation of

  12. Demonstrating the efficacy of bioventing using radiotracers

    SciTech Connect

    Baker, R.S.; Ghaemghami, J.; Simkins, S.; Mallory, L.M.

    1994-12-31

    Direct evidence to support the effectiveness of bioventing was obtained in columns simulating unsaturated zone dynamics. Fine sandy loam from the capillary fringe of a site contaminated with toluene and xylenes was packed into glass columns. Radiolabeled [U-ring-{sup 14}C] toluene and [U-ring-{sup 14}C] m-xylene were separately added to gamma-irradiated control columns and identical nonsterile columns. Toluene (or m-xylene) and CO{sub 2} present in air drawn through the soil were continuously captured in organic vapor and NaOH traps, respectively. The addition of a radiotracer to all columns permitted an accounting of the contaminant mass balance among volatilized, biodegraded, residual, and leached fractions. During two trials involving {sup 14}C-toluene and {sup 14}C-m-xylene, 46 to 57% and 40 to 46%, respectively, of the added {sup 14}C was oxidized to {sup 14}CO{sub 2} in the nonsterile columns, demonstrating that bioremediation had been effective. Volatilization of 75% of added {sup 14}C-toluene and 54% of added {sup 14}C-m-xylene occurred in the sterile controls, whereas the nonsterile columns experienced volatile losses of less than 0.4% and 0.7%, respectively. As virtually no volatile hydrocarbons were detected in the offgas over the course of the bioventing tests from the nonsterile columns, despite the high airflow rate (15 to 20 pore volumes d{sup {minus}1}), offgas treatment may prove unnecessary during bioventing of some field sites.

  13. Development of a Fluorinated Class-I HDAC Radiotracer Reveals Key Chemical Determinants of Brain Penetrance.

    PubMed

    Strebl, Martin G; Wang, Changning; Schroeder, Frederick A; Placzek, Michael S; Wey, Hsiao-Ying; Van de Bittner, Genevieve C; Neelamegam, Ramesh; Hooker, Jacob M

    2016-05-18

    Despite major efforts, our knowledge about many brain diseases remains remarkably limited. Epigenetic dysregulation has been one of the few leads toward identifying the causes and potential treatments of psychiatric disease over the past decade. A new positron emission tomography radiotracer, [(11)C]Martinostat, has enabled the study of histone deacetylase in living human subjects. A unique property of [(11)C]Martinostat is its profound brain penetrance, a feature that is challenging to engineer intentionally. In order to understand determining factors for the high brain-uptake of Martinostat, a series of compounds was evaluated in rodents and nonhuman primates. The study revealed the major structural contributors to brain uptake, as well as a more clinically relevant fluorinated HDAC radiotracer with comparable behavior to Martinostat, yet longer half-life.

  14. Evaluation of a novel radiotracer for positron emission tomography imaging of reactive oxygen species in the central nervous system.

    PubMed

    Wilson, Alan A; Sadovski, Oleg; Nobrega, José N; Raymond, Roger J; Bambico, Francis R; Nashed, Mina G; Garcia, Armando; Bloomfield, Peter M; Houle, Sylvain; Mizrahi, Romina; Tong, Junchao

    2017-06-01

    Few, if any, radiotracers are available for the in vivo imaging of reactive oxygen species (ROS) in the central nervous system. ROS play a critical role in normal cell processes such as signaling and homeostasis but overproduction of ROS is implicated in several disorders. We describe here the radiosynthesis and initial ex vivo and in vivo evaluation of [(11)C]hydromethidine ([(11)C]HM) as a radiotracer to image ROS using positron emission tomography (PET). [(11)C]HM and its deuterated isotopologue [(11)C](4) were produced using [(11)C]methyl triflate in a one-pot, two-step reaction and purified by high performance liquid chromatography. Ex vivo biodistribution studies were performed after tail vein injections of both radiotracers. To demonstrate sensitivity of uptake to ROS, [(11)C]HM was administered to rats treated systemically with lipopolysaccharide (LPS). In addition, ex vivo autoradiography and in vivo PET imaging were performed using [(11)C]HM on rats which had been microinjected with sodium nitroprusside (SNP) to induce ROS. [(11)C]HM and [(11)C](4) radiosyntheses were reliable and produced the radiotracers at high specific activities and radiochemical purities. Both radiotracers demonstrated good brain uptake and fast washout of radioactivity, but [(11)C](4) washout was faster. Pretreatment with LPS resulted in a significant increase in brain retention of radioactivity. Ex vivo autoradiography and PET imaging of rats unilaterally treated with microinjections of SNP demonstrated increased retention of radioactivity in the treated side of the brain. [(11)C]HM has the attributes of a radiotracer for PET imaging of ROS in the brain including good brain penetration and increased retention of radioactivity in animal models of oxidative stress. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Uptake of the prostate-specific membrane antigen-targeted PET radiotracer 18F-DCFPyL in elastofibroma dorsi.

    PubMed

    Gorin, Michael A; Marashdeh, Wael; Ross, Ashley E; Allaf, Mohammad E; Pienta, Kenneth J; Pomper, Martin G; Rowe, Steven P

    2017-09-01

    PET imaging using radiotracers that target prostate-specific membrane antigen (PSMA) are increasingly being used in the evaluation of men with prostate cancer (PCa). It is therefore of increasing importance for imaging specialists to recognize potential pitfalls of this novel imaging technique. In this report, we describe a series of benign elastofibroma dorsi with uptake of the PSMA-targeted PET radiotracer F-DCFPyL. We retrospectively analyzed the imaging data of 75 men with PCa who were consecutively imaged with F-DCFPyL PET/CT. Acquired images were reviewed for the presence of radiotracer uptake in the region of the scapular tip adjacent to the chest wall. Only those lesions with discrete radiotracer uptake corresponding to an area on CT with the characteristic appearance of an elastofibroma were considered positive. In total, 18/75 (24.0%) patients had evidence of at least one elastofibroma dorsi on F-DCFPyL PET/CT. Eight (44.4%) of these patients had unilateral lesions, all of which were right sided. Detected lesions had a median maximal diameter of 2.3 cm (range: 1.3-8.4 cm) and a median perpendicular thickness to the chest wall of 0.9 cm (range: 0.6-2.5 cm). The median maximum standardized uptake value of detected lesions was 1.4 (range: 1.1-2.4) and the median maximum standardized uptake value corrected to lean body mass was 1.1 (range: 0.8-1.7). This study is the first to report uptake of a PSMA-targeted PET radiotracer in elastofibroma dorsi. Radiotracer uptake in these benign lesions should not be falsely mistaken as sites of metastatic PCa.

  16. Investigation of flow behaviour of coal particles in a pilot-scale fluidized bed gasifier (FBG) using radiotracer technique.

    PubMed

    Pant, H J; Sharma, V K; Kamudu, M Vidya; Prakash, S G; Krishanamoorthy, S; Anandam, G; Rao, P Seshubabu; Ramani, N V S; Singh, Gursharan; Sonde, R R

    2009-09-01

    Knowledge of residence time distribution (RTD), mean residence time (MRT) and degree of axial mixing of solid phase is required for efficient operation of coal gasification process. Radiotracer technique was used to measure the RTD of coal particles in a pilot-scale fluidized bed gasifier (FBG). Two different radiotracers i.e. lanthanum-140 and gold-198 labeled coal particles (100 gm) were independently used as radiotracers. The radiotracer was instantaneously injected into the coal feed line and monitored at the ash extraction line at the bottom and gas outlet at the top of the gasifier using collimated scintillation detectors. The measured RTD data were treated and MRTs of coal/ash particles were determined. The treated data were simulated using tanks-in-series model. The simulation of RTD data indicated good degree of mixing with small fraction of the feed material bypassing/short-circuiting from the bottom of the gasifier. The results of the investigation were found useful for optimizing the design and operation of the FBG, and scale-up of the gasification process.

  17. New-generation radiotracers for nAChR and NET.

    PubMed

    Ding, Yu-Shin; Fowler, Joanna

    2005-10-01

    Advances in radiotracer chemistry and instrumentation have merged to make positron emission tomography (PET) a powerful tool in the biomedical sciences. Positron emission tomography has found increased application in the study of drugs affecting the brain and whole body, including the measurement of drug pharmacokinetics (using a positron-emitter-labeled drug) and drug pharmacodynamics (using a labeled tracer). Thus, radiotracers are major scientific tools enabling investigations of molecular phenomena, which are at the heart of understanding human disease and developing effective treatments; however, there is evidently a bottleneck in translating basic research to clinical practice. In the meantime, the poor ability to predict the in vivo behavior of chemical compounds based on their log P's and affinities emphasizes the need for more knowledge in this area. In this article, we focus on the development and translation of radiotracers for PET studies of the nicotinic acetylcholine receptor (nAChR) and the norepinephrine transporter (NET), two molecular systems that urgently need such an important tool to better understand their functional significance in the living human brain.

  18. High efficiency motor rewind study

    NASA Astrophysics Data System (ADS)

    Wallace, A. K.; Spee, R.

    1991-02-01

    The objective of performing this work was to evaluate a new technology used for rewinding electric motors. Motor performance evaluation was conducted at the motor test facility at Oregon State University. The test program consisted of comparing new high efficiency motor technology and standard rewind technology with the Unity-Plus system. The Unity-Plus configuration exhibited reduced efficiency over the complete load range compared to the other motors. Appropriately sized capacitors connected to the terminals of the conventional induction motor produced the same power factor improvement as the Unity-Plus system. Torque production and torque pulsation were very similar for all systems. The Unity-Plus configuration drew lower starting currents but the duration of the starting transient was increased. Motor temperature rise was about the same for all systems. Noise levels were about the same in all systems. Although determination of time to failure was not undertaken, the expected lifetime of the Unit-Plus system is probably less due to higher capacitor stress and higher insulation stress. The investigation concludes that a conventional induction motor with terminal capacitors is the most acceptable way of obtaining good efficiency and power factor and the Unity-Plus system cannot be recommended on the basis of any of the evaluation criteria used in this study.

  19. SPECT-OPT multimodal imaging enables accurate evaluation of radiotracers for β-cell mass assessments

    PubMed Central

    Eter, Wael A.; Parween, Saba; Joosten, Lieke; Frielink, Cathelijne; Eriksson, Maria; Brom, Maarten; Ahlgren, Ulf; Gotthardt, Martin

    2016-01-01

    Single Photon Emission Computed Tomography (SPECT) has become a promising experimental approach to monitor changes in β-cell mass (BCM) during diabetes progression. SPECT imaging of pancreatic islets is most commonly cross-validated by stereological analysis of histological pancreatic sections after insulin staining. Typically, stereological methods do not accurately determine the total β-cell volume, which is inconvenient when correlating total pancreatic tracer uptake with BCM. Alternative methods are therefore warranted to cross-validate β-cell imaging using radiotracers. In this study, we introduce multimodal SPECT - optical projection tomography (OPT) imaging as an accurate approach to cross-validate radionuclide-based imaging of β-cells. Uptake of a promising radiotracer for β-cell imaging by SPECT, 111In-exendin-3, was measured by ex vivo-SPECT and cross evaluated by 3D quantitative OPT imaging as well as with histology within healthy and alloxan-treated Brown Norway rat pancreata. SPECT signal was in excellent linear correlation with OPT data as compared to histology. While histological determination of islet spatial distribution was challenging, SPECT and OPT revealed similar distribution patterns of 111In-exendin-3 and insulin positive β-cell volumes between different pancreatic lobes, both visually and quantitatively. We propose ex vivo SPECT-OPT multimodal imaging as a highly accurate strategy for validating the performance of β-cell radiotracers. PMID:27080529

  20. SPECT-OPT multimodal imaging enables accurate evaluation of radiotracers for β-cell mass assessments.

    PubMed

    Eter, Wael A; Parween, Saba; Joosten, Lieke; Frielink, Cathelijne; Eriksson, Maria; Brom, Maarten; Ahlgren, Ulf; Gotthardt, Martin

    2016-04-15

    Single Photon Emission Computed Tomography (SPECT) has become a promising experimental approach to monitor changes in β-cell mass (BCM) during diabetes progression. SPECT imaging of pancreatic islets is most commonly cross-validated by stereological analysis of histological pancreatic sections after insulin staining. Typically, stereological methods do not accurately determine the total β-cell volume, which is inconvenient when correlating total pancreatic tracer uptake with BCM. Alternative methods are therefore warranted to cross-validate β-cell imaging using radiotracers. In this study, we introduce multimodal SPECT - optical projection tomography (OPT) imaging as an accurate approach to cross-validate radionuclide-based imaging of β-cells. Uptake of a promising radiotracer for β-cell imaging by SPECT, (111)In-exendin-3, was measured by ex vivo-SPECT and cross evaluated by 3D quantitative OPT imaging as well as with histology within healthy and alloxan-treated Brown Norway rat pancreata. SPECT signal was in excellent linear correlation with OPT data as compared to histology. While histological determination of islet spatial distribution was challenging, SPECT and OPT revealed similar distribution patterns of (111)In-exendin-3 and insulin positive β-cell volumes between different pancreatic lobes, both visually and quantitatively. We propose ex vivo SPECT-OPT multimodal imaging as a highly accurate strategy for validating the performance of β-cell radiotracers.

  1. Radiotracers Used for the Scintigraphic Detection of Infection and Inflammation

    PubMed Central

    Tsopelas, Chris

    2015-01-01

    Over the last forty years, a small group of commercial radiopharmaceuticals have found their way into routine medical use, for the diagnostic imaging of patients with infection or inflammation. These molecular radiotracers usually participate in the immune response to an antigen, by tagging leukocytes or other molecules/cells that are endogenous to the process. Currently there is an advancing effort by researchers in the preclinical domain to design and develop new agents for this application. This review discusses radiopharmaceuticals used in the nuclear medicine clinic today, as well as those potential radiotracers that exploit an organism's defence mechanisms to an infectious or inflammatory event. PMID:25741532

  2. The uses of radiotracers in the life sciences

    NASA Astrophysics Data System (ADS)

    Ruth, Thomas J.

    2009-01-01

    Radionuclides have been used to follow physical, chemical and biological processes almost from the time of their discovery. Probably the application with the biggest impact has been in the medical field where radionuclides have been incorporated into biologically active molecules and used to diagnose a wide variety of diseases and to treat many disorders. Other uses in the life sciences, in general, are related to using a radioactive isotope as marker for an existing species such as nitrogen-13 in plant studies or copper-67 to track copper catalysts in phytoplankton. This review describes in general terms these uses as well as providing the reader with the background related to the physical properties of radioactive decay, the concepts associated with the production of radionuclides using reactors or accelerators and the fundamentals of imaging radioactivity. The advances in imaging technology in recent years has had a profound impact on the use of radionuclides in positron emission tomography and the coupling of other imaging modalities to provide very precise insights into human disease. The variety of uses for radiotracers in science is almost boundless dependent only upon ones imagination.

  3. Pharmacokinetic evaluation of the tau PET radiotracer [18F]T807 ([18F]AV-1451) in human subjects.

    PubMed

    Wooten, Dustin; Guehl, Nicolas J; Verwer, Eline E; Shoup, Timothy M; Yokell, Daniel L; Zubcevik, Nevena; Vasdev, Neil; Zafonte, Ross D; Johnson, Keith A; El Fakhri, Georges; Normandin, Marc David

    2016-09-22

    [(18)F]T807 is a PET radiotracer developed for imaging tau protein aggregates, which are implicated in neurological disorders including Alzheimer's disease (AD) and traumatic brain injury (TBI). The current study characterizes [(18)F]T807 pharmacokinetics in human subjects using dynamic PET imaging and metabolite-corrected arterial input functions.

  4. The Production of Radionuclides for Radiotracers in Nuclear Medicine

    NASA Astrophysics Data System (ADS)

    Ruth, Thomas J.

    Medical applications represent the vast majority of the uses for radiotracers. This review addresses how accelerators are employed for the production of high purity radionuclides that are used in basic biomedical research, as well as for clinical medicine both for diagnosing disease and for treatment.

  5. Radiolabeled Cyclic RGD Peptides as Radiotracers for Imaging Tumors and Thrombosis by SPECT

    PubMed Central

    Zhou, Yang; Chakraborty, Sudipta; Liu, Shuang

    2011-01-01

    The integrin family is a group of transmembrane glycoprotein comprised of 19 α- and 8 β-subunits that are expressed in 25 different α/β heterodimeric combinations on the cell surface. Integrins play critical roles in many physiological processes, including cell attachment, proliferation, bone remodeling, and wound healing. Integrins also contribute to pathological events such as thrombosis, atherosclerosis, tumor invasion, angiogenesis and metastasis, infection by pathogenic microorganisms, and immune dysfunction. Among 25 members of the integrin family, the αvβ3 is studied most extensively for its role of tumor growth, progression and angiogenesis. In contrast, the αIIbβ3 is expressed exclusively on platelets, facilitates the intercellular bidirectional signaling (“inside-out” and “outside-in”) and allows the aggregation of platelets during vascular injury. The αIIbβ3 plays an important role in thrombosis by its activation and binding to fibrinogen especially in arterial thrombosis due to the high blood flow rate. In the resting state, the αIIbβ3 on platelets does not bind to fibrinogen; on activation, the conformation of platelet is altered and the binding sites of αIIbβ3 are exposed for fibrinogen to crosslink platelets. Over the last two decades, integrins have been proposed as the molecular targets for diagnosis and therapy of cancer, thrombosis and other diseases. Several excellent review articles have appeared recently to cover a broad range of topics related to the integrin-targeted radiotracers and their nuclear medicine applications in tumor imaging by single photon emission computed tomography (SPECT) or a positron-emitting radionuclide for positron emission tomography (PET). This review will focus on recent developments of αvβ3-targeted radiotracers for imaging tumors and the use of αIIbβ3-targeted radiotracers for thrombosis imaging, and discuss different approaches to maximize the targeting capability of cyclic RGD peptides

  6. Radiotracers For Lipid Signaling Pathways In Biological Systems

    SciTech Connect

    Gatley, S. J.

    2016-09-26

    The primary focus of this project continues to be the development of radiotracers and radiotracer methodology for studying physiology and biochemistry. The compounds that have been labeled areacylethanolamines and acylglycerols that are, as classes, represented in both in plants and in animals. In the latter, some of these act as ligands for cannabinoid receptors and they are therefore known as endocannabinoids. Cannabinoid receptors are not found in plant genomes so that plants must contain other receptors and signaling systems that use acylethanolamines. Relatively little work has been done on that issue, though acylethanolamines do modulate plant growth and stress resistance, thus possessing obvious relevance to agriculture and energy production. Progress has been described in five peer-reviewed papers and seven meeting abstracts. Preparation of 2-acylglycerol lipid messengers in high purity. A novel enzymatic synthesis was developedthat gave pure 2-acylglycerols free of any rearrrangement to the thermodynamically more stable 1(3)-acylglycerol byproducts. The method utilized 1,3-dibutyryl-2-acylglycerol substrate ethanolysis by a resinimobilized lipase. Thus, pure radiolabeled 2-acylglycerols can now be conveniently prepared just prior to their utilization. These synthetic studies were published in the Journal of Medicinal Chemistry, 2011. Diacylglycerol lipase assay methodology. Diacylglycerol lipases (DAGLs) generate 2- acylglycerols, and are thus potential targets for disease- or growth-modifying agents, by means of reducing formation of 2-acylglycerols. A radioTLC assay of the hydrolysis of radiolabeled diglyceride substrate [1''-carbon-14]2-arachidonoyl-1-stearoyl-sn-glycerol has been implemented, and used to validate a novel, potentially highthroughput fluorescence resonance energy transfer (FRET) based assay. A number of new DAGL inhibitors that have selectivity for DAGLs were synthesized and screened. This work was very recently published in Bioorganic

  7. Optical imaging of Cerenkov light generation from positron-emitting radiotracers

    PubMed Central

    Robertson, R; Germanos, M S; Li, C; Mitchell, G S; Cherry, S R; Silva, M D

    2009-01-01

    Radiotracers labeled with high-energy positron-emitters, such as those commonly used for positron emission tomography (PET) studies, emit visible light immediately following decay in a medium. This phenomenon, not previously described for these imaging tracers, is consistent with Cerenkov radiation and has several potential applications, especially for in vivo molecular imaging studies. Herein we detail a new molecular imaging tool, Cerenkov Luminescence Imaging, the experiments conducted that support our interpretation of the source of the signal, and proof-of-concept in vivo studies that set the foundation for future application of this new method. PMID:19636082

  8. Optical reaction cell and light source for [18F] fluoride radiotracer synthesis

    DOEpatents

    Ferrieri, R.A.; Schlyer, D.; Becker, R.J.

    1998-09-15

    An apparatus is disclosed for performing organic synthetic reactions, particularly no-carrier-added nucleophilic radiofluorination reactions for PET radiotracer production. The apparatus includes an optical reaction cell and a source of broadband infrared radiant energy, which permits direct coupling of the emitted radiant energy with the reaction medium to heat the reaction medium. Preferably, the apparatus includes means for focusing the emitted radiant energy into the reaction cell, and the reaction cell itself is preferably configured to reflect transmitted radiant energy back into the reaction medium to further improve the efficiency of the apparatus. The apparatus is well suited to the production of high-yield syntheses of 2-[{sup 18}F]fluoro-2-deoxy-Dglucose. Also provided is a method for performing organic synthetic reactions, including the manufacture of [{sup 18}F]-labeled compounds useful as PET radiotracers, and particularly for the preparation of 2-[{sup 18}F]fluoro-2-deoxy-D-glucose in higher yields than previously possible. 4 figs.

  9. Optical reaction cell and light source for ›18F! fluoride radiotracer synthesis

    DOEpatents

    Ferrieri, Richard A.; Schlyer, David; Becker, Richard J.

    1998-09-15

    Apparatus for performing organic synthetic reactions, particularly no-carrier-added nucleophilic radiofluorination reactions for PET radiotracer production. The apparatus includes an optical reaction cell and a source of broadband infrared radiant energy, which permits direct coupling of the emitted radiant energy with the reaction medium to heat the reaction medium. Preferably, the apparatus includes means for focusing the emitted radiant energy into the reaction cell, and the reaction cell itself is preferably configured to reflect transmitted radiant energy back into the reaction medium to further improve the efficiency of the apparatus. The apparatus is well suited to the production of high-yield syntheses of 2-›.sup.18 F!fluoro-2-deoxy-D-glucose. Also provided is a method for performing organic synthetic reactions, including the manufacture of ›.sup.18 F!-labeled compounds useful as PET radiotracers, and particularly for the preparation of 2-›.sup.18 F!fluoro-2-deoxy-D-glucose in higher yields than previously possible.

  10. Microbially mediated cobalt oxidation in seawater revealed by radiotracer experiments

    SciTech Connect

    Lee, B.G.; Fisher, N.S. )

    1993-12-01

    The influence of microbial activity on Co and Mn oxidation in decomposing diatom cultures was determined with radiotracer techniques. Adding a consortium of microorganisms collected from coastal seawater (0.2-3-[mu]m size fraction) to the cultures increased particulate Co formation rates at 18[degrees]C by an order of magnitude (to 3.8% d[sup [minus]1]) and particulate Mn formation rates 3-fold (to 7.9% d[sup [minus

  11. Guide for Conducting Energy Efficiency Potential Studies

    EPA Pesticide Factsheets

    The Guide for Conducting Energy Efficiency Potential Studies is provided to assist state officials, regulators, legislators, and others in implementing the recommendations of the National Action Plan for Energy Efficiency.

  12. Radionuclides, radiotracers and radiopharmaceuticals for in vivo diagnosis

    NASA Astrophysics Data System (ADS)

    Wiebe, Leonard I.

    Radioactive tracers for in vivo clinical diagnosis fall within a narrow, strictly-defined set of specifications in respect of their physical properties, chemical and biochemical characteristics, and (approved) medical applications. The type of radioactive decay and physical half-life of the radionuclide are immutable properties which, along with the demands of production and supply, limit the choice of radionuclides used in medicine to only a small fraction of those known to exist. In use, the biochemical and physiological properties of a radiotracer are dictated by the chemical form of the radionuclide. This chemical form may range from elemental, molecular or ionic, to complex compounds formed by coordinate or covalent bonding of the radionuclide to either simple organic or inorganic molecules, or complex macromolecules. Few of the radiotracers which are tested in model systems ever become radiopharmaceuticals in the strictest sense. Radionuclides, radiotracers and radiopharmaceuticals in use are reviewed. Drug legislation and regulations concerning drug manufacture, as well as hospital ethical constraints and legislation concerning unsealed sources of radiation must all be satisfied in order to translate a radiopharmaceutical from the laboratory to clinical use.

  13. Prediction of water vapor transport rates across polyvinylchloride packaging systems using a novel radiotracer method

    SciTech Connect

    Wood, R.W.; Mulski, M.J.; Kuu, W.Y. )

    1990-09-01

    A radiotracer method is used to study the transport properties of water vapor in polyvinylchloride (PVC), a plastic commonly used in the packaging of parenteral solutions. Water vapor transport across a PVC film appears to be Fickian in nature. Using the steady-state solution of Fick's second law and the permeability coefficient of water vapor across the PVC film obtained using the described method, the predicted water vapor transport rate (WVTR) for a parenteral solution packaged in PVC is in reasonable agreement with actual WVTR as determined by weight loss under precisely controlled conditions.

  14. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, T. R.; Lieb, D.; Oettinger, P. E.; Goodale, D. B.

    1977-01-01

    Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

  15. Effect of Cyclosporin A on the Uptake of D3-Selective PET Radiotracers in Rat Brain

    PubMed Central

    Tu, Zhude; Li, Shihong; Xu, Jinbin; Chu, Wenhua; Jones, Lynne A.; Luedtke, Robert R.; Mach, Robert H.

    2011-01-01

    Introduction Four benzamide analogs having a high affinity and selectivity for D3 versus D2 receptors were radiolabeled with 11C or 18F for in vivo evaluation. Methods Precursors were synthesized and the four D3 selective benzamide analogs were radiolabeled. The tissue distribution and brain uptake of the four compounds were evaluated in control rats and rats pretreated with cyclosporin A, a modulator of P-glycoprotein and an inhibitor of other ABC efflux transporters that contribute to the blood brain barrier. MicroPET imaging was carried out for [11C]6 in a control and a cyclosporin A pre-treated rat. Results All four compounds showed low brain uptake in control rats at 5 and 30 min post-injection; despite recently reported rat behavioral studies conducted on analogs 6 (WC-10) and 7 (WC-44). Following administration of cyclosporin A, increased brain uptake was observed with all four PET radiotracers at both 5 and 30 min post-i.v. injection. An increase in brain uptake following modulation/inhibition of the ABC transporters was also observed in the microPET study. Conclusions These data suggest that D3 selective conformationally-flexible benzamide analogs which contain a N-2-methoxyphenylpiperazine moiety are substrates for P-glycoprotein or other ABC transporters expressed at the blood-brain barrier, and that PET radiotracers containing this pharmacophore may display low brain uptake in rodents due to the action of these efflux transporters. PMID:21718948

  16. Combination of sealed source and radiotracer technique to understand malfunctioning in a chemical plant.

    PubMed

    Yelgaonkar, V N; Jayakumar, T K; Singh, Sudhir; Sharma, M K

    2009-01-01

    Pure terphthalic acid (PTA) is produced by the oxidation of paraxylene in an oxidation reactor of a PTA plant. Since the reaction is exothermic, the temperature rises above 210 degrees C. Vapours formed in the reactor are passed through a series of heat exchangers and the cooled liquid is fed back to the reactor, which flows to the reactor by gravity. In one of the heat exchangers, improper flow distribution in the inlet and outlet pipelines was suspected. Maldistribution of flow in the heat exchanger was also suspected. Gamma scanning of the pipelines and a radiotracer experiment were carried out in the heat exchanger to study the malfunctioning. A specially fabricated pipe scanner was used to scan both 24in diameter and 16in diameter pipelines. From gamma scanning of the pipelines mostly on the bends, absence of the full bore flow of the liquid was observed. Presence of vapours along with the liquid could be obstructing the liquid flow, thereby causing the malfunctioning. A radiotracer experiment was also carried out to study the flow pattern in the heat exchanger. From the experiment, mean residence time of the heat exchanger was estimated as 470s, which theoretically should be about 102s. It indicated that the flow is decelerated in the heat exchanger because of the presence of vapour lock in the tube side.

  17. Chemistry and biology of radiotracers that target changes in sympathetic and parasympathetic nervous systems in heart disease.

    PubMed

    Eckelman, William C; Dilsizian, Vasken

    2015-06-01

    Following the discovery of the sympathetic and parasympathetic nervous system, numerous adrenoceptor drugs were radiolabeled and potent radioligands were prepared in order to image the β-adrenergic and the muscarinic systems. But the greatest effort has been in preparing noradrenaline analogs, such as norepinephrine, (11)C-metahydroxyephedrine, and (123)I-metaiodobenzylguanidine that measure cardiac sympathetic nerve varicosities. Given the technical and clinical challenges in designing and validating targeted adrenoceptor-binding radiotracers, namely the heavily weighted flow dependence and relatively low target-to-background ratio, both requiring complicated mathematic analysis, and the inability of targeted adrenoceptor radioligands to have an impact on clinical care of heart disease, the emphasis has been on radioligands monitoring the norepinephrine pathway. The chemistry and biology of such radiotracers, and the clinical and prognostic impact of these innervation imaging studies in patients with heart disease, are examined.

  18. Establishment of a trimodality analytical platform for tracing, imaging and quantification of gold nanoparticles in animals by radiotracer techniques.

    PubMed

    Chen, Chien-Hung; Lin, Fong-Sian; Liao, Wei-Neng; Liang, Sanching L; Chen, Min-Hua; Chen, Yo-Wen; Lin, Wan-Yu; Hsu, Ming-Hua; Wang, Mei-Ya; Peir, Jinn-Jer; Chou, Fong-In; Chen, Ching-Ya; Chen, Sih-Yu; Huang, Su-Chin; Yang, Mo-Hsiung; Hueng, Dueng-Yuan; Hwu, Yeukuang; Yang, Chung-Shi; Chen, Jen-Kun

    2015-01-06

    This study aims to establish a (198)Au-radiotracer technique for in vivo tracing, rapid quantification, and ex vivo visualization of PEGylated gold nanoparticles (GNPs) in animals, organs and tissue dissections. The advantages of GNPs lie in its superior optical property, biocompatibility and versatile conjugation chemistry, which are promising to develop diagnostic probes and drug delivery systems. (198)Au is used as a radiotracer because it simultaneously emits beta and gamma radiations with proper energy and half-life; therefore, (198)Au can be used for bioanalytical purposes. The (198)Au-tagged radioactive gold nanoparticles ((198)Au-GNPs) were prepared simply by irradiating the GNPs in a nuclear reactor through the (197)Au(n,γ)(198)Au reaction and subsequently the (198)Au-GNPs were subjected to surface modification with polyethylene glycol to form PEGylated (198)Au-GNPs. The (198)Au-GNPs retained physicochemical properties that were the same as those of GNP before neutron irradiation. Pharmacokinetic and biodisposition studies were performed by intravenously injecting three types of (198)Au-GNPs with or without PEGylation into mice; the γ radiation in blood specimens and dissected organs was then measured. The (198)Au-radiotracer technique enables rapid quantification freed from tedious sample preparation and shows more than 95% recovery of injected GNPs. Clinical gamma scintigraphy was proved feasible to explore spatial- and temporal-resolved biodisposition of (198)Au-GNPs in living animals. Moreover, autoradiography, which recorded beta particles from (198)Au, enabled visualizing the heterogeneous biodisposition of (198)Au-GNPs in different microenvironments and tissues. In this study, the (198)Au-radiotracer technique facilitated creating a trimodality analytical platform for tracing, quantifying and imaging GNPs in animals.

  19. Designing steriod receptor-based radiotracers to image breast and prostate tumors

    SciTech Connect

    Katzenellenbogen, J.A.

    1995-06-01

    Imaging of breast or prostate cancers based on their content of steroid receptors poses a major challenge in the design of radiotracers. Receptors for steroid hormones are proteins that interact at specific sites in chromatin. Several analogs of estrogens, progestins and androgens have been radiolabeled and evaluated both in vitro and in vivo for receptor binding affinity and selectivity. Breast tumors in patients have been imaged with [{sup 18}F]fluoroestradiol. Scintigraphic images with radiolabeled progestin analogs may be useful for monitoring the efficacy of tamoxifen treatment in breast cancer patients. Tissue distribution and imaging studies in animals with fluorine-substituted androgens indicate that it may be possible to develop a steroid receptor-based radiotracer for staging prostate cancer. Radiochemists are reporting some progress in labeling steroid receptor ligands with {sup 99m}Tc. By using the techniques of molecular nuclear medicine, new imaging procedures could be developed that might provide more precise information to help characterize disease and effect treatment decisions in patients with breast or prostate cancers. 55 refs., 4 figs., 4 tabs.

  20. Development of gamma-emitting, receptor binding radiotracers for imaging the brain and pancreas

    SciTech Connect

    Reba, R.C.

    1990-01-01

    This progress report covers period from Nov. 1, 1989 to Aug. 31, 1990. The long term objective was to develop receptor-binding radiotracers for SPECT or PET imaging of CNS or peripheral nervous system. The specific chemistry aims, as understood on the basis of past findings, were: to synthesize and develop a more polar analogs of 4IQNB, possessing similar binding characteristics but eliminated more rapidly from the surrounding tissues and the target organ, to design a method of introducing a technetium chelating group onto a molecule or cholinergic agent without drastic lowering of its apparent affinity, to synthesize and develop radiotracers based on m-AChR antagonists selective for one of the subtypes of the receptor. The chemistry service aims were to prepare and characterize (R,R)- and (R,S)-4IQNB and derivatives, to provide the triazene intermediate to other investigators, and to provide ({sup 123}I)4IQNB for in vivo imaging. The biochemistry aims were to characterize the vitro and in vivo properties of novel compounds and to perform the pharmacokinetic studies. 3 refs., 5 tabs.

  1. Value of Sentinel Lymph Node (SLN) Mapping and Biopsy using Combined Intracervical Radiotracers and Blue Dye Injections for Endometrial Cancer

    PubMed

    Farzaneh, Farah; Moridi, Atefeh; Azizmohammadi, Zahra; Ansari J, Mojtaba; Hosseini, Maryam Sadat; Arab, Maliheh; Ashrafganjoei, Tahereh; Mazaheri, Mina

    2017-02-01

    Background: Lymphadenectomy, as part of the initial surgical staging of patients with endometrial carcinoma, remains a controversial topic in gynecologic oncology. Sentinel lymph node (SLN) mapping has become a well-accepted procedure for melanomas and breast cancer; a number of investigators have begun to explore the utility and accuracy of this technique with regard to endometrial cancer. Aim: This study was conducted to evaluate SLN mapping of early stage endometrial cancer with blue dye in conjunction with a radioactive tracer. Subjects and methods: In this prospective cross-sectional study, patients with stage I and II endometrial cancer who were candidates for systemic lymph node dissection during surgery were enrolled, some underwent lymph node mapping and SLN biopsy using combined intra cervical radiotracer and blue dye injections and some applying only an intra cervical radiotracer. SLNs and other lymph nodes were sent for pathological assessment. Sensitivity, specificity, the positive predictive value, and the negative predictive value were calculated as predictive values for the radiotracer and blue dye. Results: Pre-operative lymph node mapping showed SLN in 29 out of 30 patients. Intra operations in 29/30 patients, SLNs were harvested by gamma probe; in 13 out of 19 patients SLNs were detected by blue dye. The median number of SLNs per patient was 3 and the total number of SLNs detected was 81. Four patients had positive pelvic lymph nodes. All of the positive nodes were SLNs. Using this technique (radiotracer and blue dye) an overall detection rate of 96.7%, an NPV of 100%, a sensitivity of 100% and a specificity of 3.85% were achieved. Conclusion: Results of SLN research for endometrial cancer are promising and make feasible the possibility of avoiding unnecessary aggressive surgical procedures in near future by advances in SLN mapping. Creative Commons Attribution License

  2. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, D. P.; Oettinger, P. E.

    1976-01-01

    The objective is to improve thermionic converter performance by means of reduced interelectrode losses, greater emitter capabilities, and lower collector work functions until the converter performance level is suitable for out-of-core space reactors and radioisotope generators. Electrode screening experiments have identified several promising collector materials. Back emission work function measurements of a ZnO collector in a thermionic diode have given values less than 1.3 eV. Diode tests were conducted over the range of temperatures of interest for space power applications. Enhanced mode converter experiments have included triodes operated in both the surface ionization and plasmatron modes. Pulsed triodes were studied as a function of pulse length, pulse potential, inert gas fill pressure, cesium pressure, spacing, emitter temperature and collector temperature. Current amplifications (i.e., mean output current/mean grid current) of several hundred were observed up to output current densities of one amp/sq cm. These data correspond to an equivalent arc drop less than 0.1 eV.

  3. PET-Specific Parameters and Radiotracers in Theoretical Tumour Modelling

    PubMed Central

    Marcu, Loredana G.; Bezak, Eva

    2015-01-01

    The innovation of computational techniques serves as an important step toward optimized, patient-specific management of cancer. In particular, in silico simulation of tumour growth and treatment response may eventually yield accurate information on disease progression, enhance the quality of cancer treatment, and explain why certain therapies are effective where others are not. In silico modelling is demonstrated to considerably benefit from information obtainable with PET and PET/CT. In particular, models have successfully integrated tumour glucose metabolism, cell proliferation, and cell oxygenation from multiple tracers in order to simulate tumour behaviour. With the development of novel radiotracers to image additional tumour phenomena, such as pH and gene expression, the value of PET and PET/CT data for use in tumour models will continue to grow. In this work, the use of PET and PET/CT information in in silico tumour models is reviewed. The various parameters that can be obtained using PET and PET/CT are detailed, as well as the radiotracers that may be used for this purpose, their utility, and limitations. The biophysical measures used to quantify PET and PET/CT data are also described. Finally, a list of in silico models that incorporate PET and/or PET/CT data is provided and reviewed. PMID:25788973

  4. Development of a 99Mo/99mTc generator using alumina microspheres for industrial radiotracer applications.

    PubMed

    Dash, Ashutosh; Chakravarty, Rubel; Ram, Ramu; Pillai, K T; Yadav, Yugandhara Y; Wagh, D N; Verma, Rakesh; Biswas, Sujoy; Venkatesh, Meera

    2012-01-01

    A chromatographic (99)Mo/(99m)Tc generator for industrial applications has been developed using alumina microspheres synthesized through sol-gel process to obtain (99m)Tc in both aqueous and non-aqueous media. The sorbent was mesoporous, mechanically strong and possessed high surface area. (99m)Tc could be eluted from generator system using either acetone or 0.9% NaCl solution with appreciably high yields and high radiochemical as well as radionuclidic purity. The facile, versatile generator provides an efficient way to access (99m)Tc at industrial sites for radiotracer applications.

  5. Travel Efficiency Assessment Method: Three Case Studies

    EPA Pesticide Factsheets

    This slide presentation summarizes three case studies EPA conducted in partnership with Boston, Kansas City, and Tucson, to assess the potential benefits of employing travel efficiency strategies in these areas.

  6. High efficiency microfluidic beta detector for pharmacokinetic studies in small animals

    NASA Astrophysics Data System (ADS)

    Convert, Laurence; Girard-Baril, Frédérique; Renaudin, Alan; Grondin, Étienne; Jaouad, Abdelatif; Aimez, Vincent; Charette, Paul; Lecomte, Roger

    2011-10-01

    New radiotracers are continuously being developed to improve diagnostic efficiency using Single Photon Emission Computed Tomography (SPECT) or Positron Emission Tomography (PET). The characterization of their pharmacokinetics requires blood radioactivity monitoring over time during the scan and is very challenging in small animals because of the low volume of blood available. In this work, a prototype microfluidic blood counter made of a microchannel atop a silicon substrate containing PIN photodiodes is proposed to improve beta detection efficiency in a small volume by eliminating unnecessary interfaces between fluid and detector. A flat rectangular-shaped epoxy channel, 36 μm×1.26 mm cross section and 31.5 mm in length, was microfabricated over a die containing an array of 2×2 mm 2 PIN photodiodes, leaving only a few micrometers of epoxy floor layer between the fluid and the photodiode sensitive surface. This geometry leads to a quasi 2D source, optimizing geometrical detection efficiency that was estimated at 41% using solid angle calculation. CV- IV measurements were made at each fabrication step to confirm that the microchannel components had no significant effects on the diodes' electrical characteristics. The chip was wire-bonded to a PCB and connected to charge sensitive preamplifier and amplifier modules for pulse shaping. Energy spectra recorded for different isotopes showed continuous beta distribution for PET isotopes and monoenergetic conversion electron peaks for 99mTc. Absolute sensitivity was determined for the most popular PET and SPECT radioisotopes and ranged from 26% to 33% for PET tracers ( 18F, 13N, 11C, 68Ga) and more than 2% for 99mTc. Input functions were successfully simulated with 18F, confirming the setup's suitability for pharmacokinetic modeling of PET and SPECT radiotracers in animal experiments. By using standard materials and procedures, the fabrication process is well suited to on-chip microfluidic functionality, allowing full

  7. Design Study of Small Efficient Cryocoolers.

    DTIC Science & Technology

    1980-11-01

    I~ V 1k I HL I 1 o’i AL A19 9 0 8 (92 DESIGN STUDY OF SMALL EFFICIENT CRYOCOOLERS PHILIPS LABORATORIES A Division of North American Philips...REPORT A PERIOD COVERED Final Technical Report DESIGN SJDY OF SMALL EFFICIENT CRYOCOOLERS April 14 - Sept. 11, 1980 6. PERFORMING ORG. REPORT NUMBER 7... Stirling cycle refrigerator linear motor cryogenic refrigerator for 100K triple-expansion Stirling -cycle refrigerator free-displacer, free-piston

  8. Radiotracer imaging of dopaminergic transmission in neuropsychiatric disorders.

    PubMed

    Verhoeff, N P

    1999-12-01

    This article will review the capabilities and accomplishments of radiotracer imaging with single photon emission computed tomography (SPECT) and positron emission tomography (PET) to measure pre-, post-, and "intra-synaptic" aspects of dopaminergic (DAergic) neurotransmission. The presynaptic site can be labeled with probes for the dopamine transporter (DAT) or the synthetic enzyme aromatic L-amino acid decarboxylase ("dopa decarboxylase"). The postsynaptic sites can be labeled with probes for either the dopamine D1 receptor (D1R) or the dopamine D2 receptor (D2R). The "synaptic" measurements are made indirectly by measurements of the interaction/displacement of receptor tracers by endogenous dopamine (DA). Agents are used which either release (e.g., amphetamine) or deplete (e.g., alpha-methyl-paratyrosine (AMPT), an inhibitor of tyrosine hydroxylase) tissue stores of DA. The application of these paradigms will be reviewed with special emphasis to neuropsychiatric diseases such as schizophrenia and idiopathic Parkinson's disease (IPD).

  9. Radiotracers for Cardiac Sympathetic Innervation: Transport Kinetics and Binding Affinities for the Human Norepinephrine Transporter

    PubMed Central

    Raffel, David M.; Chen, Wei; Jung, Yong-Woon; Jang, Keun Sam; Gu, Guie; Cozzi, Nicholas V.

    2013-01-01

    Introduction Most radiotracers for imaging of cardiac sympathetic innervation are substrates of the norepinephrine transporter (NET). The goal of this study was to characterize the NET transport kinetics and binding affinities of several sympathetic nerve radiotracers, including [11C]-(−)-meta-hydroxyephedrine, [11C]-(−)-epinephrine, and a series of [11C]-labeled phenethylguanidines under development in our laboratory. For comparison, the NET transport kinetics and binding affinities of some [3H]-labeled biogenic amines were also determined. Methods Transport kinetics studies were performed using rat C6 glioma cells stably transfected with the human norepinephrine transporter (C6-hNET cells). For each radiolabeled NET substrate, saturation transport assays with C6-hNET cells measured the Michaelis-Menten transport constants Km and Vmax for NET transport. Competitive inhibition binding assays with homogenized C6-hNET cells and [3H]mazindol provided estimates of binding affinities (KI) for NET. Results Km, Vmax and KI values were determined for each NET substrate with a high degree of reproducibility. Interestingly, C6-hNET transport rates for ‘tracer concentrations’ of substrate, given by the ratio Vmax/Km, were found to be highly correlated with neuronal transport rates measured previously in isolated rat hearts (r2 = 0.96). This suggests that the transport constants Km and Vmax measured using the C6-hNET cells accurately reflect in vivo transport kinetics. Conclusion The results of these studies show how structural changes in NET substrates influence NET binding and transport constants, providing valuable insights that can be used in the design of new tracers with more optimal kinetics for quantifying regional sympathetic nerve density. PMID:23306137

  10. Experimental observation of silver and gold penetration into dental ceramic by means of a radiotracer technique

    SciTech Connect

    Moya, F.; Payan, J.; Bernardini, J.; Moya, E.G.

    1987-12-01

    A radiotracer technique was used to study silver and gold diffusion into dental porcelain under experimental conditions close to the real conditions in prosthetic laboratories for porcelain bakes. It was clearly shown that these non-oxidizable elements were able to diffuse into the ceramic as well as oxidizable ones. The penetration depth varied widely according to the element. The ratio DAg/DAu was about 10(3) around 850 degrees C. In contrast to gold, the silver diffusion rate was high enough to allow silver, from the metallic alloy, to be present at the external ceramic surface after diffusion into the ceramic. Hence, the greening of dental porcelains baked on silver-rich alloys could be explained mainly by a solid-state diffusion mechanism.

  11. Flow Rate Measurement Using {sup 99m}Tc Radiotracer Method in a Pipe Installation

    SciTech Connect

    Sipaun, S. M.; Bakar, A. Q. Abu; Othman, N.; Shaari, M. R.; Adnan, M. A. K.; Yusof, J. Mohd; Demanah, R.

    2010-07-07

    Flow rate is a significant parameter for managing processes in chemical processing plants and water processing facility. Accurate measurement of the flow rate allows engineers to monitor the delivery of process material, which in turn impacts a plant's capacity to produce their products. One of the available methods for determining the flow rate of a process material is by introducing a radiotracer to the system that mimics the material's flow pattern. In this study, a low activity Technetium-99m radioisotope was injected into a water piping setup and the 2'' x 2'' NaI (Tl) detectors were calibrated to detect spectrum peaks at specific points of the pipe installation. Using pulse velocity method, water flow rate was determined to be 11.3 litres per minute. For the sampling method, at different pump capacity, the flow rate was 15.0 litres per minute.

  12. Ultra-efficient Engine Diameter Study

    NASA Technical Reports Server (NTRS)

    Daggett, David L.; Brown, Stephen T.; Kawai, Ron T.

    2003-01-01

    Engine fan diameter and Bypass Ratio (BPR) optimization studies have been conducted since the beginning of the turbofan age with the recognition that reducing the engine core jet velocity and increasing fan mass flow rate generally increases propulsive efficiency. However, performance tradeoffs limit the amount of fan flow achievable without reducing airplane efficiency. This study identifies the optimum engine fan diameter and BPR, given the advanced Ultra-Efficient Engine Technology (UEET) powerplant efficiencies, for use on an advanced subsonic airframe. Engine diameter studies have historically focused on specific engine size options, and were limited by existing technology and transportation infrastructure (e.g., ability to fit bare engines through aircraft doors and into cargo holds). This study is unique in defining the optimum fan diameter and drivers for future 2015 (UEET) powerplants while not limiting engine fan diameter by external constraints. This report follows on to a study identifying the system integration issues of UEET engines. This Engine Diameter study was managed by Boeing Phantom Works, Seattle, Washington through the NASA Glenn Revolutionary Aero Space Engine Research (RASER) contract under task order 10. Boeing Phantom Works, Huntington Beach, completed the engine/airplane sizing optimization, while the Boeing Commercial Airplane group (BCA) provided design oversight. A separate subcontract to support the overall project was issued to Tuskegee University.

  13. Quantification of radiotracer uptake with a dedicated breast PET imaging system.

    PubMed

    Raylman, Raymond R; Smith, Mark F; Kinahan, Paul E; Majewski, Stan

    2008-11-01

    Tomographic breast imaging techniques can be used to quantify radiotracer uptake in breast and tumor tissue. However, physical processes common to PET imaging can confound accurate quantification. In this investigation, we assessed the effects of these phenomena and tested correction schemes for our new positron emission mammography-tomography system (PEM-PET). The PEM-PET scanner utilizes two sets of rotating planar detector heads. Each unit consists of a 4×3 array of Hamamatsu H8500 flat panel position sensitive photomultipliers coupled to a 96×72 array of 2×2×15mm3 LYSO detector elements (pitch=2.1mm). Image reconstruction is performed with a 3D-OSEM algorithm parallelized to run on a multiprocessor computer system. The reconstructed field-of-view is 15×15×15cm3. Much of the testing procedures were based on NEMA-NU2/2001 protocols. Count rate losses due to pulse pile-up, image contamination due to acceptance of random coincidences and Compton scatter, and image artifacts produced by photon attenuation were measured. It was found that the system was susceptible to count rate losses when moderate levels of radiation were present in the scanner due to the current design of the event trigger electronics. Application of corrections for Compton scattering, photon attenuation and dead time resulted in improved estimations of F18 concentration in simplified phantom studies. Results from these preliminary studies indicate that the PEM-PET scanner will be useful for the quantification of radiotracer uptake in breast tumors, possibly facilitating early assessment of cancer treatments. © 2008 American Association of Physicists in Medicine.

  14. Quantification of radiotracer uptake with a dedicated breast PET imaging system.

    PubMed

    Raylmana, Raymond R; Smith, Mark F; Kinahan, Paul E; Majewski, Stan

    2008-11-01

    Tomographic breast imaging techniques can be used to quantify radiotracer uptake in breast and tumor tissue. However, physical processes common to PET imaging can confound accurate quantification. In this investigation, we assessed the effects of these phenomena and tested correction schemes for our new positron emission mammography-tomography system (PEM-PET). The PEM-PET scanner utilizes two sets of rotating planar detector heads. Each unit consists of a 4 x 3 array of Hamamatsu H8500 flat panel position sensitive photomultipliers coupled to a 96 x 72 array of 2 x 2 x 15 mm3 LYSO detector elements (pitch = 2.1 mm). Image reconstruction is performed with a 3D-OSEM algorithm parallelized to run on a multiprocessor computer system. The reconstructed field-of-view is 15 x 15 x 15 cm3. Much of the testing procedures were based on NEMA-NU2/2001 protocols. Count rate losses due to pulse pile-up, image contamination due to acceptance of random coincidences and Compton scatter, and image artifacts produced by photon attenuation were measured. It was found that the system was susceptible to count rate losses when moderate levels of radiation were present in the scanner due to the current design of the event trigger electronics. Application of corrections for Compton scattering, photon attenuation and dead time resulted in improved estimations of 18F concentration in simplified phantom studies. Results from these preliminary studies indicate that the PEM-PET scanner will be useful for the quantification of radiotracer uptake in breast tumors, possibly facilitating early assessment of cancer treatments.

  15. Quantification of radiotracer uptake with a dedicated breast PET imaging system

    PubMed Central

    Raylman, Raymond R.; Smith, Mark F.; Kinahan, Paul E.; Majewski, Stan

    2008-01-01

    Tomographic breast imaging techniques can be used to quantify radiotracer uptake in breast and tumor tissue. However, physical processes common to PET imaging can confound accurate quantification. In this investigation, we assessed the effects of these phenomena and tested correction schemes for our new positron emission mammography–tomography system (PEM–PET). The PEM–PET scanner utilizes two sets of rotating planar detector heads. Each unit consists of a 4×3 array of Hamamatsu H8500 flat panel position sensitive photomultipliers coupled to a 96×72 array of 2×2×15 mm3 LYSO detector elements (pitch=2.1 mm). Image reconstruction is performed with a 3D-OSEM algorithm parallelized to run on a multiprocessor computer system. The reconstructed field-of-view is 15×15×15 cm3. Much of the testing procedures were based on NEMA-NU2∕2001 protocols. Count rate losses due to pulse pile-up, image contamination due to acceptance of random coincidences and Compton scatter, and image artifacts produced by photon attenuation were measured. It was found that the system was susceptible to count rate losses when moderate levels of radiation were present in the scanner due to the current design of the event trigger electronics. Application of corrections for Compton scattering, photon attenuation and dead time resulted in improved estimations of 18F concentration in simplified phantom studies. Results from these preliminary studies indicate that the PEM–PET scanner will be useful for the quantification of radiotracer uptake in breast tumors, possibly facilitating early assessment of cancer treatments. PMID:19070233

  16. Methods for studying close-track efficiency

    SciTech Connect

    Mac Mestayer; Konstantin Mikhaylov; Aleksey Stavinskiy; Alexander Vlassov

    2004-05-01

    Wire chambers used for particle tracking suffer a loss of efficiency when the trajectories of two particles from the same event are very close together in space. We describe two new methods for the study of this close-track efficiency. One is based on the study of a correlation function for particles with different masses as a function of their relative momenta in the laboratory reference system. The other method is based on the analysis of artificial events, constructed by merging raw data from separate events. Both methods and the standard Monte Carlo method were applied to data from the CLAS detector at Jefferson Laboratory. All three methods provide the same result for close-track efficiency with an accuracy sufficient for practical application.

  17. Long Half-life (89)Zr Labeled Radiotracers Can Guide In Suite Percutaneous Molecular Imaging PET/CT-guided Biopsies Without Reinjection of Radiotracer.

    PubMed

    Cornelis, Francois H; Durack, Jeremy; Pandit-Taskar, Neeta; Ulaner, Gary A; Lewis, Jason S; Morris, Michael J; Solomon, Stephen B

    2017-08-17

    Rationale: To evaluate the feasibility of in suite Zr89 labeled radiotracer positron emission tomography-computed tomography (PET/CT)-guided biopsies performed without reinjection. Methods: From 2013-2016, 12 patients (7 males, 5 females; mean age 61 years, range 40-75) with suspected metastatic prostate or breast carcinoma on either imaging or biochemical progression underwent 14 percutaneous biopsies after diagnostic PET/CT using (89)Zr labeled radiotracers (mean dose: 180MBq; range: 126-189MBq) targeting prostate specific membrane antigen (PSMA) (n = 7) or human epidermal growth factor receptor 2 (HER2) (n = 5). Biopsies were performed in a PET/CT suite without radiotracer reinjection. Results: Biopsies were performed without complications a mean of 6.2 days (range, 0-13) after injection of radiotracers in bone (n = 7), pleura (n = 3), lymph nodes (n = 2) and liver (n = 2). All biopsies were positive for malignancy on pathology. A concordance between the initial diagnostic imaging findings and biopsies results was observed. The additional radiation (mean dose length product) due to CT procedures was 1581 mGy/cm (379-2686). No complications were reported. Conclusion: Molecular imaging PET/CT-guided biopsies using (89)Zr labeled radiotracers are safe and effective without tracer reinjection. Copyright © 2017 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  18. Functional investigation of bone implant viability using radiotracers in a new model of osteonecrosis

    PubMed Central

    Schiper, Luis; Faintuch, Bluma Linkowski; da Silva Badaró, Roberto José; de Oliveira, Erica Aparecida; Chavez, Victor E. Arana; Chinen, Elisangela; Faintuch, Joel

    2016-01-01

    OBJECTIVES: Conventional imaging methods are excellent for the morphological characterization of the consequences of osteonecrosis; however, only specialized techniques have been considered useful for obtaining functional information. To explore the affinity of radiotracers for severely devascularized bone, a new mouse model of isolated femur implanted in a subcutaneous abdominal pocket was devised. To maintain animal mobility and longevity, the femur was harvested from syngeneic donors. Two technetium-99m-labeled tracers targeting angiogenesis and bone matrix were selected. METHODS: Medronic acid and a homodimer peptide conjugated with RGDfK were radiolabeled with technetium-99m, and biodistribution was evaluated in Swiss mice. The grafted and control femurs were evaluated after 15, 30 and 60 days, including computed tomography (CT) and histological analysis. RESULTS: Radiolabeling achieved high (>95%) radiochemical purity. The biodistribution confirmed good blood clearance 1 hour after administration. For 99mTc-hydrazinonicotinic acid (HYNIC)-E-[c(RGDfK)2, remarkable renal excretion was observed compared to 99mTc-methylene diphosphonate (MDP), but the latter, as expected, revealed higher bone uptake. The results obtained in the control femur were equal at all time points. In the implanted femur, 99mTc-HYNIC-E-[c(RGDfK)2 uptake was highest after 15 days, consistent with early angiogenesis. Regarding 99mTc-MDP in the implant, similar uptake was documented at all time points, consistent with sustained bone viability; however, the uptake was lower than that detected in the control femur, as confirmed by histology. CONCLUSIONS: 1) Graft viability was successfully diagnosed using radiotracers in severely ischemic bone at all time points. 2) Analogously, indirect information about angiogenesis could be gathered using 999mTc-HYNIC-E-[c(RGDfK)2. 3) These techniques appear promising and warrant further studies to determine their potential clinical applications. PMID

  19. Amyloid PET imaging in Alzheimer’s disease: A comparison of three radiotracers

    PubMed Central

    Landau, SM.; Thomas, BA.; Thurfjell, L.; Schmidt, M.; Margolin, R.; Mintun, M.; Pontecorvo, M.; Baker, SL.; Jagust, WJ.

    2014-01-01

    Purpose The increasing use of amyloid PET in Alzheimer’s disease research and clinical trials has motivated efforts to standardize methodology. We compared tracer retention for 11C radiotracer Pittsburgh Compound B (PiB) with two 18F amyloid radiotracers (florbetapir and flutemetamol) using two study populations. We also examined the feasibility of converting between tracer-specific measures, using PiB as the common link between the two 18F tracers. Methods One group of subjects (N=40) underwent PiB and flutemetamol imaging sessions and a separate group (N=32) underwent PiB and florbetapir imaging sessions. We compared cortical and white matter retention for each F18 tracer relative to PiB, as well as several reference regions and image analysis methods. Associations between tracer pairs were used to convert thresholds for amyloid positivity between tracer-specific values. Results Cortical retention for each pair of tracers was strongly correlated regardless of reference region (flutemetamol-PiB, ρ=0.84–0.99; florbetapir-PiB, ρ=0.83–0.97) and analysis method (ρ=0.90–0.99). Compared to PiB, flutemetamol had higher white matter retention, while florbetapir had lower cortical retention. Two previously established independent thresholds for amyloid positivity were highly consistent when values were converted between tracer pairs. Conclusions Despite differing white and grey matter retention characteristics, cortical retention for each F18 tracer was highly correlated with PiB, enabling conversion of thresholds across tracer measurement scales with a high level of internal consistency. Standardization of analysis methods and measurement scales may facilitate the comparison of amyloid PET data obtained using different tracers. PMID:24647577

  20. The Study on Energy Efficiency in Africa

    NASA Astrophysics Data System (ADS)

    Wu, Jinduo

    This paper is dedicated to explore the dynamic performance of energy efficiency in Africa, with panel data in country level, taking energy yield, power consumption, electricity transmission and distribution losses into account, the paper employ stochastic frontier mode,highlighting a dummy variable in energy output in terms of net imports of energy and power, which minify the deviation of estimated variables. The results show that returns of scale did not appear in energy and power industry in Africa, electricity transmission and distribution losses contribute most to GDP per unit of energy. In country level, Republic of Congo and Botswana suggest an obvious energy efficiency advantage. Energy efficiency in Mozambique and Democratic Republic of Congo are not very satisfying during the studying year

  1. Energy-efficient electric motors study

    SciTech Connect

    Not Available

    1981-03-23

    The study identifies the industrial decision makers, investigated the information they needed to know, how they can best be reached, and the motivating factors for purchasing energy-efficient electric motors. A survey was conducted of purchasers of integral horsepower polyphase motors. The survey measured current knowledge of and awareness of energy-efficient motors, decision-making criteria, information sources, purchase and usage patterns, and related factors. The survey data were used for the electric motor market penetration analysis. Additionally, a telephone survey was made. The study also provides analyses of distribution channels, commercialization constraints, and the impacts of government programs and rising energy prices. A description of study findings, conclusions, and recommendations is presented. Sample questionnaires and copies of letters to respondents are presented in 3 appendices. Appendices D and E contain descriptions of the methods used. (MCW)

  2. In vivo vulnerability to competition by endogenous dopamine: comparison of the D2 receptor agonist radiotracer (-)-N-[11C]propyl-norapomorphine ([11C]NPA) with the D2 receptor antagonist radiotracer [11C]-raclopride.

    PubMed

    Narendran, Rajesh; Hwang, Dah-Ren; Slifstein, Mark; Talbot, Peter S; Erritzoe, David; Huang, Yiyun; Cooper, Thomas B; Martinez, Diana; Kegeles, Lawrence S; Abi-Dargham, Anissa; Laruelle, Marc

    2004-06-01

    (-)-N-Propyl-norapomorphine (NPA) is a full dopamine (DA) D2 receptor agonist and [11C]NPA is a suitable radiotracer to image D2 receptors configured in a state of high affinity for agonists with positron emission tomography (PET). In this study the vulnerability of the in vivo binding of [11C]NPA to acute fluctuation in synaptic DA was assessed with PET in baboons and compared to that of the reference D2 receptor antagonist radiotracer [11C]raclopride. Three male baboons were studied with [11C]raclopride and [11C]NPA under baseline conditions and following administration of the potent DA releaser amphetamine (0.3, 0.5, and 1.0 mg kg(-1) i.v.). Kinetic modeling with an arterial input function was used to derive the striatal specific-to-nonspecific equilibrium partition coefficient (V3"). [11C]Raclopride V3" was reduced by 24 +/- 10%, 32 +/- 6%, and 44 +/- 9% following amphetamine doses of 0.3, 0.5, and 1.0 mg kg(-1), respectively. [11C]NPA V3" was reduced by 32 +/- 2%, 45 +/- 3%, and 53 +/- 9% following amphetamine doses of 0.3, 0.5, and 1.0 mg kg(-1), respectively. Thus, endogenous DA was more effective at competing with [11C]NPA binding compared to [11C]raclopride binding, a finding consistent with the pharmacology of these tracers (agonist vs. antagonist). These results also suggest that 71% of D2 receptors are configured in a state of high affinity for agonists in vivo. In conclusion, [11C]NPA might provide a superior radiotracer to probe presynaptic DA function with PET in health and disease.

  3. OpenPET: A Flexible Electronics System for Radiotracer Imaging

    PubMed Central

    Moses, W. W.; Buckley, S.; Vu, C.; Peng, Q.; Pavlov, N.; Choong, W.-S.; Wu, J.; Jackson, C.

    2011-01-01

    We present the design for OpenPET, an electronics readout system designed for prototype radiotracer imaging instruments. The critical requirements are that it has sufficient performance, channel count, channel density, and power consumption to service a complete camera, and yet be simple, flexible, and customizable enough to be used with almost any detector or camera design. An important feature of this system is that each analog input is processed independently. Each input can be configured to accept signals of either polarity as well as either differential or ground referenced signals. Each signal is digitized by a continuously sampled ADC, which is processed by an FPGA to extract pulse height information. A leading edge discriminator creates a timing edge that is “time stamped” by a TDC implemented inside the FPGA. This digital information from each channel is sent to an FPGA that services 16 analog channels, and information from multiple channels is processed by this FPGA to perform logic for crystal lookup, DOI calculation, calibration, etc. As all of this processing is controlled by firmware and software, it can be modified / customized easily. The system is open source, meaning that all technical data (specifications, schematics and board layout files, source code, and instructions) will be publicly available. PMID:21297894

  4. [11C]CURB: Evaluation of a novel radiotracer for imaging fatty acid amide hydrolase by positron emission tomography.

    PubMed

    Wilson, Alan A; Garcia, Armando; Parkes, Jun; Houle, Sylvain; Tong, Junchao; Vasdev, Neil

    2011-02-01

    Fatty acid amide hydrolase (FAAH) is the enzyme responsible for metabolising the endogenous cannabinoid, anandamide, and thus represents an important target for molecular imaging. To date, no radiotracer has been shown to be useful for imaging of FAAH using either positron emission tomography (PET) or single photon emission computed tomography (SPECT). We here determine the suitability of a novel carbon-11-labeled inhibitor of FAAH via ex vivo biodistribution studies in rat brain in conjunction with pharmacological challenges. A potent irreversible inhibitor of FAAH, URB694, radiolabeled with carbon-11 in the carbonyl position ([(11)C]CURB), was administered to male rats via tail-vein injection. Rats were sacrificed at various time points postinjection, and tissue samples were dissected, counted and weighed. Specific binding to FAAH was investigated by pretreatment of animals with URB694 or URB597. For metabolism and mechanism of binding studies, whole brains were excised post-radiotracer injection, homogenised and extracted exhaustively with 80% aq. acetonitrile to determine the time course and fraction of radioactivity that was irreversibly bound to brain parenchyma. Upon intravenous injection into rats, [(11)C]CURB showed high brain uptake [standard uptake value (SUV) of 1.6-2.4 at 5 min] with little washout over time, which is characteristic of irreversible binding. Highest uptake of radioactivity was seen in the cortex, intermediate in the cerebellum and lowest in the hypothalamus, reflecting the reported distribution of FAAH. Brain uptake of radioactivity was decreased in a dose-dependent manner by pretreatment with increasing amounts of URB694, demonstrating that binding was saturable. Pretreatment with the well-characterised FAAH inhibitor, URB597, reduced binding in all brain regions by 70-80%. Homogenised brain extraction experiments demonstrated unequivocally that [(11)C]CURB was irreversibly bound to FAAH. The title radiotracer demonstrates favourable

  5. Energy-efficient electric motors study

    NASA Astrophysics Data System (ADS)

    1981-03-01

    A survey conducted of purchasers of integral horsepower polyphase motors measured current knowledge of and awareness of energy efficient motors, decision making criteria, information sources, purchase and usage patterns, and related factors. The data obtained were used for the electric motor market penetration analysis. Additionally, a telephone survey was made. The study also provides analyses of distribution channels, commercialization constraints, and the impacts of government programs and rising energy prices. Study findings, conclusions, and recommendations are presented. Sample questionnaires and copies of letters to respondents are presented in appendices as well as descriptions of the methods used.

  6. The host plant Pinus pinaster exerts specific effects on phosphate efflux and polyphosphate metabolism of the ectomycorrhizal fungus Hebeloma cylindrosporum: a radiotracer, cytological staining and (31) P NMR spectroscopy study.

    PubMed

    Torres-Aquino, Margarita; Becquer, Adeline; Le Guernevé, Christine; Louche, Julien; Amenc, Laurie K; Staunton, Siobhan; Quiquampoix, Hervé; Plassard, Claude

    2017-02-01

    Ectomycorrhizal (ECM) association can improve plant phosphorus (P) nutrition. Polyphosphates (polyP) synthesized in distant fungal cells after P uptake may contribute to P supply from the fungus to the host plant if they are hydrolyzed to phosphate in ECM roots then transferred to the host plant when required. In this study, we addressed this hypothesis for the ECM fungus Hebeloma cylindrosporum grown in vitro and incubated without plant or with host (Pinus pinaster) and non-host (Zea mays) plants, using an experimental system simulating the symbiotic interface. We used (32) P labelling to quantify P accumulation and P efflux and in vivo and in vitro nuclear magnetic resonance (NMR) spectroscopy and cytological staining to follow the fate of fungal polyP. Phosphate supply triggered a massive P accumulation as newly synthesized long-chain polyP in H. cylindrosporum if previously grown under P-deficient conditions. P efflux from H. cylindrosporum towards the roots was stimulated by both host and non-host plants. However, the host plant enhanced (32) P release compared with the non-host plant and specifically increased the proportion of short-chain polyP in the interacting mycelia. These results support the existence of specific host plant effects on fungal P metabolism able to provide P in the apoplast of ectomycorrhizal roots.

  7. Scaling Studies of Efficient Raman Converters.

    DTIC Science & Technology

    1983-07-01

    with injection pulse lengths as short as 35 ns. This suggests that appropriate _ electric-discharge pumped XeF lasers with spectral tuning may be...the course of this study, we have demonstrated injection locking of an e-beam pumped XeF laser to a narrow spectral bandwidth with high efficiency...electric-discharge- pumped XeF laser may provide adequate in- jection radiation to control larger, e-beam excited XeF lasers . The analysis of repetitively

  8. Wisconsin collector-efficiency study, phase two

    SciTech Connect

    Abright, B.L.

    1982-01-15

    The collector efficiency study developed a solar collector rating methodology specific to Wisconsin conditions. Existing rating programs were researched and a collector methodology was developed. A computer program was written to calculate the collector ratings and 25 collector models were rated. The accuracy of the proposed rating methodology was evaluated for 16 collectors placed in 11 domestic hot water systems. One liquid space heating analysis with storage and one air space heating analysis without storage were completed. A solar assisted heat pump in which the solar collectors function as evaporators was also analyzed.

  9. Separation of analyte and matrix for the direct analysis of high-purity molybdenum-based materials by electrothermal atomic spectrometry methods—I. Radiotracer investigation of thermal extraction of impurities in a graphite cup

    NASA Astrophysics Data System (ADS)

    Dočekal, Bohumil; Krivan, Viliam; Franek, Martin

    1994-06-01

    By means of radiotracers, thermal vaporization of a number of detrimental trace elements (alkali, alkali earth and heavy metals) from metallic molybdenum powder has been studied. For this purpose, molybdenum samples labelled with appropriate radiotracers of the trace elements were prepared from a slurry of molybdenum oxide, ammonium molybdate solution and a radiotracer solution. Vaporization yields were measured after electrothermal treatment of the samples at temperatures between 1900 and 3000°C. Alkali and alkali earth elements, copper and zinc were vaporized with yields higher than 98%. Possible application of the electrothermal vaporization technique to the direct analysis of high-purity molybdenumbased materials by atomic absorption and atomic emission spectrometry is discussed.

  10. Efficient Study Design for Next Generation Sequencing

    PubMed Central

    Sampson, Joshua; Jacobs, Kevin; Yeager, Meredith; Chanock, Stephen; Chatterjee, Nilanjan

    2011-01-01

    Next Generation Sequencing represents a powerful tool for detecting genetic variation associated with human disease. Because of the high cost of this technology, it is critical that we develop efficient study designs that consider the trade-off between the number of subjects (n) and the coverage depth (μ). How we divide our resources between the two can greatly impact study success, particularly in pilot studies. We propose a strategy for selecting the optimal combination of n and μ for studies aimed at detecting rare variants and for studies aimed at detecting associations between rare or uncommon variants and disease. For detecting rare variants, we find the optimal coverage depth to be between 2 and 8 reads when using the likelihood ratio test. For association studies, we find the strategy of sequencing all available subjects to be preferable. In deriving these combinations, we provide a detailed analysis describing the distribution of depth across a genome and the depth needed to identify a minor allele in an individual. The optimal coverage depth depends on the aims of the study, and the chosen depth can have a large impact on study success. PMID:21370254

  11. Comparison of Amino Acid Positron Emission Tomographic Radiotracers for Molecular Imaging of Primary and Metastatic Brain Tumors

    PubMed Central

    Juhász, Csaba; Dwivedi, Shalini; Kamson, David O.; Michelhaugh, Sharon K.; Mittal, Sandeep

    2014-01-01

    Positron emission tomography (PET) is an imaging technology that can detect and characterize tumors based on their molecular and biochemical properties, such as altered glucose, nucleoside, or amino acid metabolism. PET plays a significant role in the diagnosis, prognostication, and treatment of various cancers, including brain tumors. In this article, we compare uptake mechanisms and the clinical performance of the amino acid PET radiotracers (l-[methyl-11C]methionine [MET], 18F-fluoroethyl-tyrosine [FET], 18F-fluoro-l-dihydroxy-phenylalanine [FDOPA], and 11C-alpha-methyl-l-tryptophan [AMT]) most commonly used for brain tumor imaging. First, we discuss and compare the mechanisms of tumoral transport and accumulation, the basis of differential performance of these radioligands in clinical studies. Then we summarize studies that provided direct comparisons among these amino acid tracers and to clinically used 2-deoxy-2[18F]fluoro-d-glucose [FDG] PET imaging. We also discuss how tracer kinetic analysis can enhance the clinical information obtained from amino acid PET images. We discuss both similarities and differences in potential clinical value for each radioligand. This comparative review can guide which radiotracer to favor in future clinical trials aimed at defining the role of these molecular imaging modalities in the clinical management of brain tumor patients. PMID:24825818

  12. A new method for SPECT quantification of targeted radiotracers uptake in the myocardium.

    PubMed

    Li, Shimin; Dobrucki, Lawrence W; Sinusas, Albert J; Liu, Yi-Hwa

    2005-01-01

    We developed a new method for absolute quantification of targeted radiotracers uptake in the myocardium using hybrid SPECT/CT and an external reference point source. A segmentation algorithm based on the level set was developed to determine the endocardial edges from CT, which were subsequently applied to the physically co-registered SPECT. A 3-D Gaussian fitting method was applied for quantification of the external point source. The total targeted radiotracer activity in the myocardium was normalized to that in the point source to calculate the absolute uptake of targeted radiotracer in the myocardium. Preliminary validation was performed in rats with ischemia-induced angiogenesis. The quantified in vivo radiotracer uptake was compared to the postmortem tissue radioactive well-counting of the myocardium. Our methods worked well for identification of the endocardial edges. Quantification of the focal uptake was consistent with the well-counting data. Our methods may have the potential of providing precise absolute quantification of targeted radiotracer uptake in the myocardium.

  13. Field study of energy-efficient showerheads

    SciTech Connect

    Bailey, S.A.; Warwick, W.M.; Lauhala, A.J.; Hickman, C.H.; Dent, C.L.

    1992-09-01

    In August 1991, the Bonneville Power Administration (Bonneville) initiated an energy-efficient showerhead performance assessment project. Approximately 98 homes are participating in this study. All are metered under the Regional End-Use Metering Program (REMP), which is operated by the Pacific Northwest Laboratory (PNL) for Bonneville. Hourly pre- and post-retrofit electrical water heating consumption data will be analyzed using the REMP data archive. The goal of this study is to identify factors affecting energy savings from retrofit of energy-efficient shower heads which will be used to develop an ``algorithm`` to credit participants in retrofit programs with savings. This algorithm must be easy to apply, credible, and adoptable to conditions which may vary among utilities in Bonneville`s Pacific Northwest service area. This field data collection project was designed to collect information about site and occupant characteristics that may affect participation and performance. These data are used to verify or modify assumptions used in engineering models to project energy savings. Estimates of measure performance based on comparisons of energy use are not included in this paper because sufficient post-retrofit data is not yet available. Field data failed to confirm several critical assumptions used to project energy savings. Showerhead water flow rates and anticipated reductions from the retrofit measures were less than expected. Participation in this voluntary study was relatively low considering its risk- and cost-free design. Finally, barriers were encountered that prevented retrofits at some participating sites. The cumulative effect of all factors could reduce projected savings 70% over initial engineering estimates, if 100% participation is assumed.

  14. Field study of energy-efficient showerheads

    SciTech Connect

    Bailey, S.A.; Warwick, W.M.; Lauhala, A.J. ); Hickman, C.H. ); Dent, C.L. )

    1992-09-01

    In August 1991, the Bonneville Power Administration (Bonneville) initiated an energy-efficient showerhead performance assessment project. Approximately 98 homes are participating in this study. All are metered under the Regional End-Use Metering Program (REMP), which is operated by the Pacific Northwest Laboratory (PNL) for Bonneville. Hourly pre- and post-retrofit electrical water heating consumption data will be analyzed using the REMP data archive. The goal of this study is to identify factors affecting energy savings from retrofit of energy-efficient shower heads which will be used to develop an algorithm'' to credit participants in retrofit programs with savings. This algorithm must be easy to apply, credible, and adoptable to conditions which may vary among utilities in Bonneville's Pacific Northwest service area. This field data collection project was designed to collect information about site and occupant characteristics that may affect participation and performance. These data are used to verify or modify assumptions used in engineering models to project energy savings. Estimates of measure performance based on comparisons of energy use are not included in this paper because sufficient post-retrofit data is not yet available. Field data failed to confirm several critical assumptions used to project energy savings. Showerhead water flow rates and anticipated reductions from the retrofit measures were less than expected. Participation in this voluntary study was relatively low considering its risk- and cost-free design. Finally, barriers were encountered that prevented retrofits at some participating sites. The cumulative effect of all factors could reduce projected savings 70% over initial engineering estimates, if 100% participation is assumed.

  15. Cyclotron production and potential clinical application of Iodine-124 labeled radiotracers

    NASA Astrophysics Data System (ADS)

    Finn, R.; Balatoni, J.; Kothari, P.; Pentlow, K.; Sheh, Y.; Lom, C.; Dahl, J.; Eckelman, W.; Plascjak, P.; Adams, H. R.; Larson, S. M.

    2001-07-01

    Positron emission tomography (PET) is a dynamic molecular imaging technique applicable to clinical research, drug development as well as clinical diagnoses. The potential for PET is derived from specificity of the radiotracers and radioligands that are synthesized to monitor the biochemical or physiological processes. Further developments will depend on an increasing availability of unique radiotracers. Iodine-124, a radionuclide that has potential for both diagnostic and therapeutic applications, possesses a half-life of 4.18 days and decays by positron emission (23.3%) and electron capture (76.7%). The preparation of this radionuclide via the 124Te(p,n)124I nuclear reaction is described as well as chemistry associated with the preparation of specific radiotracers and radiopharmaceuticals incorporating iodine-124 at Memorial Sloan-Kettering Cancer Center.

  16. Synthesis and biological characterisation of 18F-SIG343 and 18F-SIG353, novel and high selectivity σ2 radiotracers, for tumour imaging properties

    PubMed Central

    2013-01-01

    Background Sigma2 (σ2) receptors are highly expressed in cancer cell lines and in tumours. Two novel selective 18F-phthalimido σ2 ligands, 18F-SIG343 and 18F-SIG353, were prepared and characterised for their potential tumour imaging properties. Methods Preparation of 18F-SIG343 and 18F-SIG353 was achieved via nucleophilic substitution of their respective nitro precursors. In vitro studies including radioreceptor binding assays in the rat brain membrane and cell uptake studies in the A375 cell line were performed. In vivo studies were carried out in mice bearing A375 tumours including positron emission tomography (PET) imaging, biodistribution, blocking and metabolite studies. Results In vitro studies showed that SIG343 and SIG353 displayed excellent affinity and selectivity for σ2 receptors (Ki(σ2) = 8 and 3 nM, σ2:σ1 = 200- and 110-fold, respectively). The σ2 selectivity of 18F-SIG343 was further confirmed by blocking studies in A375 cells, however, not noted for 18F-SIG353. Biodistribution studies showed that both radiotracers had similar characteristics including moderately high tumour uptake (4%ID/g to 5%ID/g); low bone uptake (3%ID/g to 4%ID/g); and high tumour-to-muscle uptake ratios (four- to sevenfold) up to 120 min. Although radiotracer uptake in organs known to express σ receptors was significantly blocked by pre-injection of competing σ ligands, the blocking effect was not observed in the tumour. PET imaging studies indicated major radioactive localisation in the chest cavity for both ligands, with approximately 1%ID/g uptake in the tumour at 120 min. Metabolite studies showed that the original radiotracers remained unchanged 65% to 80% in the tumour up to 120 min. Conclusions The lead ligands showed promising in vitro and in vivo characteristics. However, PET imaging indicated low tumour-to-background ratios. Furthermore, we were unable to demonstrate that uptake in the A375 tumour was σ2-specific. 18F-SIG343 and 18F-SIG343 do not

  17. 18F-THK5351: A Novel PET Radiotracer for Imaging Neurofibrillary Pathology in Alzheimer Disease.

    PubMed

    Harada, Ryuichi; Okamura, Nobuyuki; Furumoto, Shozo; Furukawa, Katsutoshi; Ishiki, Aiko; Tomita, Naoki; Tago, Tetsuro; Hiraoka, Kotaro; Watanuki, Shoichi; Shidahara, Miho; Miyake, Masayasu; Ishikawa, Yoichi; Matsuda, Rin; Inami, Akie; Yoshikawa, Takeo; Funaki, Yoshihito; Iwata, Ren; Tashiro, Manabu; Yanai, Kazuhiko; Arai, Hiroyuki; Kudo, Yukitsuka

    2016-02-01

    Imaging of neurofibrillary pathology in the brain helps in diagnosing dementia, tracking disease progression, and evaluating the therapeutic efficacy of antidementia drugs. The radiotracers used in this imaging must be highly sensitive and specific for tau protein fibrils in the human brain. We developed a novel tau PET tracer, (18)F-THK5351, through compound optimization of arylquinoline derivatives. The in vitro binding properties, pharmacokinetics, and safety of (18)F-THK5351 were investigated, and a clinical study on Alzheimer disease (AD) patients was performed. (18)F-THK5351 demonstrated higher binding affinity for hippocampal homogenates from AD brains and faster dissociation from white-matter tissue than did (18)F-THK5117. The THK5351 binding amount correlated with the amount of tau deposits in human brain samples. Autoradiography of brain sections revealed that THK5351 bound to neurofibrillary tangles selectively and with a higher signal-to-background ratio than did THK5117. THK5351 exhibited favorable pharmacokinetics and no defluorination in mice. In first-in-human PET studies in AD patients, (18)F-THK5351 demonstrated faster kinetics, higher contrast, and lower retention in subcortical white matter than(18)F-THK5117. (18)F-THK5351 is a useful PET tracer for the early detection of neurofibrillary pathology in AD patients. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  18. Distributed Microprocessor Automation Network for Synthesizing Radiotracers Used in Positron Emission Tomography [PET

    DOE R&D Accomplishments Database

    Russell, J. A. G.; Alexoff, D. L.; Wolf, A. P.

    1984-09-01

    This presentation describes an evolving distributed microprocessor network for automating the routine production synthesis of radiotracers used in Positron Emission Tomography. We first present a brief overview of the PET method for measuring biological function, and then outline the general procedure for producing a radiotracer. The paper identifies several reasons for our automating the syntheses of these compounds. There is a description of the distributed microprocessor network architecture chosen and the rationale for that choice. Finally, we speculate about how this network may be exploited to extend the power of the PET method from the large university or National Laboratory to the biomedical research and clinical community at large. (DT)

  19. Distributed microprocessor automation network for synthesizing radiotracers used in positron emission tomography

    SciTech Connect

    Russell, J.A.G.; Alexoff, D.L.; Wolf, A.P.

    1984-09-01

    This presentation describes an evolving distributed microprocessor network for automating the routine production synthesis of radiotracers used in Positron Emission Tomography. We first present a brief overview of the PET method for measuring biological function, and then outline the general procedure for producing a radiotracer. The paper identifies several reasons for our automating the syntheses of these compounds. There is a description of the distributed microprocessor network architecture chosen and the rationale for that choice. Finally, we speculate about how this network may be exploited to extend the power of the PET method from the large university or National Laboratory to the biomedical research and clinical community at large. 20 refs. (DT)

  20. Development of a system for real-time measurements of metabolite transport in plants using short-lived positron-emitting radiotracers

    NASA Astrophysics Data System (ADS)

    Kiser, Matthew R.

    be introduced to plants as biologically active molecules such as 11CO2, N13O-3, 18F--[H2O], and H152O . Plants for these studies are grown in controlled-environment chambers at the Phytotron. The chambers offer an array of control for temperature, humidity, atmospheric CO2 concentration, and light intensity. Additionally, the Phytotron houses one large reach-in growth chamber that is dedicated to this project for radioisotope labeling measurements. There are several important properties of short-lived positron-emitting radio-tracers that make them well suited for use in investigating metabolite transport in plants. First, because the molecular mass of a radioisotope-tagged compound is only minutely different from the corresponding stable compound, radiotracer substances should be metabolized and transported in plants the same as their non-radioactive counterparts. Second, because the relatively high energy gamma rays emitted from electron-positron annihilation are attenuated very little by plant tissue, the real-time distribution of a radiotracer can be measured in vivo in plants. Finally, the short radioactive half-lives of these isotopes allow for repeat measurements on the same plant in a short period of time. For example, in studies of short-term environmental changes on plant metabolite dynamics, a single plant can be labeled multiple times to measure its responses to different, environmental conditions. Also, different short-lived radiotracers can be applied to the same plant over a short period of time to investigate the transport and allocation of various metabolites. This newly developed system provides the capabilities for production of 11CO2 at TUNL, transfer of the 11CO 2 gas from the target area at TUNL to a radiation-shielded cryogenic trap at the Phytotron, labeling of photoassimilates with 11C, and in vivo gamma-ray detection for real-time measurements of the radiotracer distribution in small plants. The experimental techniques and instrumentation

  1. Design and evaluation of radiotracers for determination of regional cerebral blood flow with PET

    SciTech Connect

    Lambrecht, R.M.; Duncan, C.C.; Shiue, C.Y.

    1982-01-01

    The tracer kinetics of 4-Fluoro(/sup 18/F)-, 4-Bromo(/sup 82/Br)- and 4-Iodo(/sup 125/I)-antipyrine and /sup 15/O-water were compared in a cat or baboon animal model. First-pass cerebral extraction and clearance with alterations in PaCO/sub 2/ were measured for whole brain. The Renkin/Crone model was used to evaluate brain capillary permeability-surface area product for 4-/sup 18/FAP in cats. Positron-emission-tomographic measurements required development of an instrument and technique for control of the arterial concentration of the radiotracer as a ramp function, so that tracer concentration changes due to radioactive decay or altered physiological processes could be accurately described with PET. Pharmacokinetic and tissue-distribution studies in cats were used to determine dosimetry for 4-/sup 18/FAP. 4-Bromoantipyrine labeled with /sup 78/Br (t = 6.5 m) is suggested as a tracer for determination of rCBF with PET.

  2. Investigating phosphorus uptake in anoxic and sulfidic surface sediments with 33P radiotracer experiments

    NASA Astrophysics Data System (ADS)

    Dijkstra, Nikki; Kraal, Peter; Gonzalez, Santiago; Slomp, Caroline

    2016-04-01

    Phosphorus (P) is a key nutrient for marine organisms. Enhanced P availability in the water column can fuel algal blooms and the development of bottom water anoxia. Recently, it was suggested that micro-organisms in sediments overlain by anoxic and sulfidic bottom waters might take up dissolved P and form Fe(II)-P minerals, thereby enhancing P removal. In this study, we investigated the uptake of P in surface sediments with 33P radiotracer experiments. The sediments were recovered from the anoxic and sulfidic deep basin of the Black Sea and, for comparison, from the adjacent oxic shelf. Results suggest a very fast sedimentary uptake of 33P at all sites but in particular for sediments from the oxic shelf. At all sites, most 33P was sequestered in the citrate-dithionite-bicarbonate-(CDB)-extractable sediment P fraction. No significant differences with abiotic controls were observed, implying that micro-organisms were not directly involved in the P uptake. Whereas 33P uptake by the oxic shelf sediment was likely controlled by sorption of 33P to iron(Fe)-(oxyhydr)oxides, the nature of the CDB-extractable P fraction in the deep basin sediments remains unclear. We discuss whether authigenic formation of Fe(II)-P minerals or fast adsorption of P to calcites may explain our findings.

  3. Design of a serotonin 4 receptor radiotracer with decreased lipophilicity for single photon emission computed tomography.

    PubMed

    Fresneau, Nathalie; Dumas, Noé; Tournier, Benjamin B; Fossey, Christine; Ballandonne, Céline; Lesnard, Aurélien; Millet, Philippe; Charnay, Yves; Cailly, Thomas; Bouillon, Jean-Philippe; Fabis, Frédéric

    2015-04-13

    With the aim to develop a suitable radiotracer for the brain imaging of the serotonin 4 receptor subtype (5-HT4R) using single photon emission computed tomography (SPECT), we synthesized and evaluated a library of di- and triazaphenanthridines with lipophilicity values which were in the range expected to favour brain penetration, and which demonstrated specific binding to the target of interest. Adding additional nitrogen atoms to previously described phenanthridine ligands exhibiting a high unspecific binding, we were able to design a radioiodinated compound [(125)I]14. This compound exhibited a binding affinity value of 0.094 nM toward human 5-HT4R and a high selectivity over other serotonin receptor subtypes (5-HTR). In vivo SPECT imaging studies and competition experiments demonstrated that the decreased lipophilicity (in comparison with our previously reported compounds 4 and 5) allowed a more specific labelling of the 5-HT4R brain-containing regions. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  4. Biochemical quantification of sympathetic nervous activity in humans using radiotracer methodology: fallibility of plasma noradrenaline measurements

    SciTech Connect

    Esler, M.; Leonard, P.; O'Dea, K.; Jackman, G.; Jennings, G.; Korner, P.

    1982-01-01

    We have developed radiotracer techniques for studying noradrenaline kinetics, to assess better sympathetic nervous system function in humans. Tritiated l-noradrenaline was infused intravenously (0.35 microCi/m2/min) to plateau plasma concentration. Noradrenaline plasma clearance was calculated from plasma tritiated noradrenaline concentration at steady state, and the rate of spillover of noradrenaline to plasma derived from plasma noradrenaline specific radioactivity. Mean noradrenaline spillover at rest in 34 normal subjects was 0.33 micrograms/m2/min (range 0.17-0.61 micrograms/m2/min). Predictably, noradrenaline spillover was reduced in patients with subnormal sympathetic nervous system activity, 0.16 +/- 0.09 micrograms/m2/min in eight patients with idiopathic peripheral autonomic insufficiency, and 0.11 +/- 0.07 micrograms/m2/min (mean +/- SD) in six patients with essential hypertension treated with clonidine (0.45 mg daily). Noradrenaline line plasma clearance in normal subjects was 1.32 +/- 0.28 L/m2/min. Clearance fell with age, causing the previously described rise in plasma noradrenaline concentration with aging. Unexpected effects of drugs were encountered, for example chronic beta-adrenergic blockade in patients with essential hypertension reduced noradrenaline clearance. Plasma noradrenaline concentration measurements were not in agreement with noradrenaline release rate values, and do not reliably indicate sympathetic nervous system activity, in instances such as these where noradrenaline clearance is abnormal.

  5. Batch-reactor microfluidic device: first human use of a microfluidically produced PET radiotracer.

    PubMed

    Lebedev, Artem; Miraghaie, Reza; Kotta, Kishore; Ball, Carroll E; Zhang, Jianzhong; Buchsbaum, Monte S; Kolb, Hartmuth C; Elizarov, Arkadij

    2013-01-07

    The very first microfluidic device used for the production of (18)F-labeled tracers for clinical research is reported along with the first human Positron Emission Tomography scan obtained with a microfluidically produced radiotracer. The system integrates all operations necessary for the transformation of [(18)F]fluoride in irradiated cyclotron target water to a dose of radiopharmaceutical suitable for use in clinical research. The key microfluidic technologies developed for the device are a fluoride concentration system and a microfluidic batch reactor assembly. Concentration of fluoride was achieved by means of absorption of the fluoride anion on a micro ion-exchange column (5 μL of resin) followed by release of the radioactivity with 45 μL of the release solution (95 ± 3% overall efficiency). The reactor assembly includes an injection-molded reactor chip and a transparent machined lid press-fitted together. The resulting 50 μL cavity has a unique shape designed to minimize losses of liquid during reactor filling and liquid evaporation. The cavity has 8 ports for gases and liquids, each equipped with a 2-way on-chip mechanical valve rated for pressure up to 20.68 bar (300 psi). The temperature is controlled by a thermoelectric heater capable of heating the reactor up to 180 °C from RT in 150 s. A camera captures live video of the processes in the reactor. HPLC-based purification and reformulation units are also integrated in the device. The system is based on "split-box architecture", with reagents loaded from outside of the radiation shielding. It can be installed either in a standard hot cell, or as a self-shielded unit. Along with a high level of integration and automation, split-box architecture allowed for multiple production runs without the user being exposed to radiation fields. The system was used to support clinical trials of [(18)F]fallypride, a neuroimaging radiopharmaceutical under IND Application #109,880.

  6. Evaluation of bone-seeking novel radiotracer (68)Ga-NO2AP-Bisphosphonate for the detection of skeletal metastases in carcinoma breast.

    PubMed

    Passah, Averilicia; Tripathi, Madhavi; Ballal, Sanjana; Yadav, Madhav Prasad; Kumar, Rajeev; Roesch, Frank; Meckel, Marian; Sarathi Chakraborty, Partha; Bal, Chandrasekhar

    2017-01-01

    The successful labelling of bisphosphonates (BP) with (68)Ga using macrocyclic chelators such as the based triazacyclononane (NO2AP) is a step forward in the in-house availability of a novel bone-seeking PET radiopharmaceutical with dual advantage of PET/CT imaging and generator production. In this study, we compared the novel generator-based skeletal radiotracer (68)Ga-1,4,7-triazacyclonone-1,4-diacetic acid ((68)Ga-NO2AP-BP) with sodium fluoride ((18)F-NaF) for the detection of skeletal metastases in breast cancer patients. In addition, dosimetric analysis of (68)Ga-NO2AP-BP was performed in a subset of patients. This was a prospective study of histopathologically proven cases of breast cancer patients who were referred for bone scintigraphy and underwent positron emission tomography/computed tomography (PET/CT) with (18)F-NaF and (68)Ga-NO2AP-BP within a week in random order. The scans of each patient were compared both qualitatively for image quality and quantitatively for number of lesions and SUVmax of lesions. Dosimetric analysis was performed in five patients. Their PET/CT scans were acquired at multiple time points and urine and blood samples were collected. Dosimetric calculations were performed using OLINDA/EXM 1.1 software. Statistical analysis was done using Stata 13 (StataCorp) software package. An agreement analysis regarding number of lesions detected with the two skeletal radiotracers was carried out. The image quality of (68)Ga-NO2AP-BP PET/CT scans were comparable to that of (18)F-NaF. There was no statistically significant difference in the SUVmax of lesions, normal bone and lesion to background ratio between the two skeletal radiotracers. There was good agreement in the number of lesions detected by both skeletal radiotracers. The mean whole body effective dose for (68)Ga-NO2AP-BP was 0.00583 mSv/MBq and the effective dose equivalent was 0.0086 mSv/MBq. The excellent lesion detection agreement between (68)Ga-NO2AP-BP and (18)F-NaF favours the

  7. Use of supercritical carbon dioxide fluid as a solvent for the purification of pet radiotracers

    SciTech Connect

    Ferrieri, R.A.; Fowler, J.S.; Wolf, A.P.

    1993-12-31

    We have identified superfluid chromatography (SFC) as a promising method which could offer advantages in radiotracer purification through rapid separation, as well as, improved recovery and purity of labeled product. Using SF CO{sub 2} as the mobile phase for chromatographic separation of labeled product would eliminate the need for solvent removal from product prior to delivery.

  8. Increasing the accuracy of radiotracer monitoring in one-dimensional flow using polynomial deconvolution correction.

    PubMed

    Gholipour Peyvandi, Reza; Taheri, Ali

    2016-01-01

    Factors such as type of fluid movement and gamma-ray scattering may decrease the precision of the radiotracer monitoring as the response to a short tracer injection. Practical experiences using polynomial deconvolution techniques are presented. These techniques were successfully applied for correcting the obtained experimental results and increasing the time resolution of the method. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. An Investigation of the Effectiveness of Radiotracer Techniques for Instruction in Microbiology.

    ERIC Educational Resources Information Center

    Hurlburt, Evelyn McClelland

    Students in a junior college microbiology course were randomly assigned to one of two laboratory treatments: one using radiotracer techniques to investigate aspects of microbial metabolism, and the other using conventional techniques to investigate the same metabolic features. An achievement test administered at the completion of the unit and six…

  10. PET imaging of HSV1-tk mutants with acquired specificity toward pyrimidine- and acycloguanosine-based radiotracers.

    PubMed

    Likar, Yury; Dobrenkov, Konstantin; Olszewska, Malgorzata; Shenker, Larissa; Cai, Shangde; Hricak, Hedvig; Ponomarev, Vladimir

    2009-08-01

    The aim of this study was to create an alternative mutant of the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene with reduced phosphorylation capacity for acycloguanosine derivatives, but not pyrimidine-based compounds that will allow for successful PET imaging. A new mutant of HSV1-tk reporter gene, suitable for PET imaging using pyrimidine-based radiotracers, was developed. The HSV1-tk mutant contains an arginine-to-glutamine substitution at position 176 (HSV1-R176Qtk) of the nucleoside binding region of the enzyme. The mutant-gene product showed favorable enzymatic characteristics toward pyrimidine-based nucleosides, while exhibiting reduced activity with acycloguanosine derivatives. In order to enhance HSV1-R176Qtk reporter activity with pyrimidine-based radiotracers, we introduced the R176Q substitution into the more active HSV1-sr39tk mutant. U87 human glioma cells transduced with the HSV1-R176Qsr39tk double mutant reporter gene showed high (3)H-FEAU pyrimidine nucleoside and low (3)H-penciclovir acycloguanosine analog uptake in vitro. PET imaging also demonstrated high (18)F-FEAU and low (18)F-FHBG accumulation in HSV1-R176Qsr39tk+ xenografts. The feasibility of imaging two independent nucleoside-specific HSV1-tk mutants in the same animal with PET was demonstrated. Two opposite xenografts expressing the HSV1-R176Qsr39tk reporter gene and the previously described acycloguanosine-specific mutant of HSV1-tk, HSV1-A167Ysr39tk reporter gene, were imaged using a short-lived pyrimidine-based (18)F-FEAU and an acycloguanosine-based (18)F-FHBG radiotracer, respectively, administered on 2 consecutive days. We conclude that in combination with acycloguanosine-specific HSV1-A167Ysr39tk reporter gene, a HSV1-tk mutant containing the R176Q substitution could be used for PET imaging of two different cell populations or concurrent molecular biological processes in the same living subject.

  11. Study of the Efficiency of STIRAP

    NASA Astrophysics Data System (ADS)

    Sun, Yuan; Zakharov, Vladislav; Metcalf, Harold

    2014-05-01

    We measure the efficiency of the STIRAP process in exciting 23S metastable He atoms (He*) to Rydberg states. Atoms in a beam are excited to 33P by λ = 389 nm light (blue), and from there to Rydberg states by ~ 800 nm (red) light. The parallel laser beams are perpendicular to the atomic beam, arranged so that the atoms encounter the red light first (in counterintuitive order), partially overlapping with the blue. Although the lasers are CW, the atoms fly through their mm-size beams at v ~ 1070 m/s so they see μs pulses of light. The primary detection scheme uses a stainless steel detector (SSD) as a target from which He* can efficiently eject an electron. A bichromatic light beam at λ = 1083 nm exerts a strong transverse force on He* atoms that deflects them into the offset SSD, but Rydberg atoms are unaffected, thus allowing an absolute measure of the Rydberg atoms. A secondary detection method exploits the relative ease of ionizing Rydberg atoms by background blackbody radiation. The efficiency of Rydberg production is partly limited by the residual transverse velocity spread of the atomic beam, causing Doppler broadening. This will be partially remedied with an optical molasses for transverse cooling just before the STIRAP region. Supported by ONR.

  12. Barriers to Industrial Energy Efficiency - Study (Appendix A), June 2015

    SciTech Connect

    2015-06-01

    This study examines barriers that impede the adoption of energy efficient technologies and practices in the industrial sector, and identifies successful examples and opportunities to overcome these barriers. Three groups of energy efficiency technologies and measures were examined: industrial end-use energy efficiency, industrial demand response, and industrial combined heat and power. This study also includes the estimated economic benefits from hypothetical Federal energy efficiency matching grants, as directed by the Act.

  13. In situ lithium diffusion measurement in solid ionic conductors using short-lived radiotracer beam of 8Li

    NASA Astrophysics Data System (ADS)

    Ishiyama, H.; Jeong, S. C.; Watanabe, Y. X.; Hirayama, Y.; Imai, N.; Miyatake, H.; Oyaizu, M.; Osa, A.; Otokawa, Y.; Matsuda, M.; Nishio, K.; Makii, H.; Sato, T. K.; Kuwata, N.; Kawamura, J.; Nakao, A.; Ueno, H.; Kim, Y. H.; Kimura, S.; Mukai, M.

    2015-07-01

    We developed an in situ radiotracer method for diffusion studies in solids using short-lived α-emitting 8Li tracer. In the method, while implanting a pulsed 8Li beam into a solid material of interest, the α particles emitted into the implantation side of the sample surface were detected as a function of time. By changing the implantation depth and the detection angle against the sample surface according to lithium diffusivity (deep implantation and large angle with a large solid angle, or shallow implantation and small angle with a narrow solid angle), the method can be sensitive to a wide range of diffusion length ranging from micrometer scale to nanometer scale per second. The feasibility of the method was demonstrated by measuring the lithium diffusion coefficients to the order of 10-12 cm2/s in lithium ionic conductors.

  14. SU-E-I-80: Beta-Minus Emitting Radiotracers Improves Molecular Endoscopy

    SciTech Connect

    Carpenter, C; Ma, X; Sun, C; Pratx, G; Cheng, Z; Xing, L

    2014-06-01

    Purpose: Molecular Endoscopy using Cerenkov Luminescence can be used to monitor the distribution of many clinically-available PET and SPECT probes for endoscopic applications. A main limitation of Cerenkov is its limited sensitivity to small concentrations of radiotracer when using light guides s. Herein we demonstrate that the use of a high energy beta emitting radioisotope, exemplified here with 90Y provides superior sensitivity to 18F because of its higher light output and its lack of corresponding gamma emission. Methods: A series of phantom experiments were performed to compare the sensitivity and noise of the CLE system for imaging 90Y and 18F. Three vials of known concentrations of 90Y (0.008 μCi, 0.08 μCi, 1 μCi) were placed in centrifuge tubes and isolated from each other. One vial of 18F (100 μCi) was placed in the imaging chamber and imaged over the course of decay (19 hours, 43 minutes, or ∼10 half-lives). Image time-points were formed from 5-minute integrations. Results: Using an SNR of 10 to define the noise-floor, the 90Y minimum detectable activity was 0.056 μCi. To the contrast, the minimum detectable activity for 18F was 11.63 μCi. These data demonstrate a 207-fold improvement in SNR of 90Y compared to 18F, when controlled for activity. Conclusion: This study demonstrated that a pure β- radionuclide such as 90Y be used is superior to 18F for Cerenkov Endoscopy. Further study is needed to demonstrate its utility in preclinical studies, endoscopic applications, intraoperative, and radiotherapy applications.

  15. Evaluation of 64Cu-Labeled Acridinium Cation: A PET Radiotracer Targeting Tumor Mitochondria

    PubMed Central

    Zhou, Yang; Kim, Young-Seung; Shi, Jiyun; Jacobson, Orit; Chen, Xiaoyuan; Liu, Shuang

    2011-01-01

    This report presents the synthesis and evaluations of 64Cu(DO3A-xy-ACR) (DO3A-xy-ACR = 2,6-bis(dimethylamino)-10-(4-((4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)methyl)benzyl)acridin-10-ium) as a radiotracer for imaging tumors in athymic nude mice bearing U87MG glioma xenografts by PET (positron emission tomography). The biodistribution data suggested that 64Cu(DO3A-xy-ACR) was excreted mainly through the renal system with >65% of injected radioactivity being recovered from urine samples at 1 h post-injection (p.i.). The tumor uptake of 64Cu(DO3A-xy-ACR) was 1.07 ± 0.23, 1.58 ± 0.55, 2.71 ± 0.66, 3.47 ± 1.19, and 3.52 ± 1.72 %ID/g at 0.5, 1, 2, 4 and 24 h p.i., respectively. 64Cu(DO3A-xy-ACR) had very high liver uptake (31.90 ± 3.98, 24.95 ± 5.64, 15.20 ± 4.29, 14.09 ± 6.82, and 8.18 ± 1.27 %ID/g at 0.5, 1, 2, 4 and 24 h p.i., respectively) with low tumor/liver ratios. MicroPET studies showed that the tumors were clearly visualized as early as 30 min p.i. in the glioma-bearing mouse administered with 64Cu(DO3A-xy-ACR). The high liver radioactivity accumulation was also seen. 64Cu(DO3A-xy-ACR) had a relatively high metabolic stability during excretion via both renal and hepatobiliary routes; but it was completely decomposed in the liver homogenate. We explored the localization mechanism of Cu(DO3A-xy-ACR) using both U87MG human glioma and the cultured primary U87MG glioma cells. The results from the cellular staining assays showed that 64Cu(DO3A-xy-ACR) is able to localize in the mitochondria of living U87MG glioma cells due to the enhanced negative mitochondrial potential as compared to normal cells. Although 64Cu(DO3A-xy-ACR) is not an ideal PET radiotracer for tumor imaging due to its high liver uptake, the results from this study strongly suggest that 64Cu-labeled acridinium cations are indeed able to localize in the energized mitochondria of tumor cells. PMID:21413736

  16. [Tumor targeting efficacy of a novel PET radiotracer (1)8F-AlF-NOTA-PRGD2 in mice].

    PubMed

    Wu, Hubing; Wang, Quanshi; Han, Yanjiang; Zhou, Wenlan; Li, Hongsheng; Tian, Ying; Wang, Qiaoyu

    2014-01-01

    To investigate the tumor targeting efficacy of (18)F-AlF-NOTA-PRGD2, a novel radiotracer of Arginine-glycine-aspartic acid (RGD) peptides. (18)F-AlF-NOTA-PRGD2 was synthesized in one-step by conjugating NOTA-PRGD2 with (18)F-AlF at 100 degrees celsius;. The tumor targeting efficacy and in vivo biodistribution profile of (18)F-AlF-NOTA-PRGD2, following intravenous injection via the tail vein, were evaluated in a nude mouse model bearing subcutaneous U87MG glioblastoma xenograft by radioactivity biodistribution assessment, PET/CT and microPET/CT. NOTA-PRGD2 was (18)F-fluorinated successfully in one-step with a yield of 17%-25% within 15-20 min. Radioactivity biodistribution study confirmed the tumor-targeting ability of (18)F-AlF-NOTA-PRGD2 in the tumor-bearing mice. At 1 and 2 h following injection, (18)F-AlF-NOTA-PRGD2 uptake in the tumor reached 4.14∓1.44 and 2.80∓1.18 % ID/g (t=1.910, P=0.070) with tumor/brain ratios of 2.95∓0.61 and 5.21∓2.62, respectively (t=-1.686, P=0.167). Both PET/CT and microPET/CT were capable of showing the radioactivity biodistribution of (18)F-AlF-NOTA-PRGD2 in the mouse model and clearly displayed the tumor, but microPET/CT showed a much better image quality. (18)F-AlF-NOTA-PRGD2 prepared by one-step radiosynthesis can selectively target to the tumor, demonstrating its potential as a good radiotracer for tumor imaging.

  17. Improving AMS Detection of the Biomedical Radiotracer 41Ca with Segmented Radio-Frequency Quadrupoles

    NASA Astrophysics Data System (ADS)

    Alary, Jean-Francois; Javahery, Gholamreza; Kieser, William E.; Litherland, Albert E.; Cousins, Lisa M.

    41Ca is an important biomedical radiotracer finding many applications in biological, nutritional and medical studies. The detection of 41Ca by AMS is however limited by an important background signal of 41K originating from biological samples and from contaminated cesium in the source. An approach consisting of using PbF2-assisted in-source fluorination in combination with an Isobar Separator for Anions (ISA), a device incorporating a low energy radio frequency quadrupole (RFQ) gas cell, promises to push down the limit of detection of 41Ca attainable on small (<3 MV) accelerator mass spectrometry (AMS) systems by several orders of magnitude. Such on-line reduction of 41K should also result in a simplification of biological sample preparation and less concern about variable 41K contamination of the cesium beam. The selective collision-induced fragmentation of KF3- versus CaF3-, occurring in the gas cell of an ISA equipped with a double segment RFQ, have been reported earlier1), leading to K being suppressed by a factor of 1e4 over Ca. We present here the future configuration of the ISA, redesigned using multi-segmented RFQ to enhance further this effect and improve transmission through the gas cell. A segmented RFQ is an appropriate tool to finely control ion energy down to the few eV's separating the fragmentation energies of the two fluoride species. This pre-commercial ISA destined to be used at the newly established A. E. Lalonde AMS laboratory at University of Ottawa (Canada) will be presented. Some practicalities of integrating a low energy RFQ-based device in a high energy AMS system will also be discussed.

  18. Operationally efficient propulsion system study (OEPSS) data book. Volume 6; Space Transfer Propulsion Operational Efficiency Study Task of OEPSS

    NASA Technical Reports Server (NTRS)

    Harmon, Timothy J.

    1992-01-01

    This document is the final report for the Space Transfer Propulsion Operational Efficiency Study Task of the Operationally Efficient Propulsion System Study (OEPSS) conducted by the Rocketdyne Division of Rockwell International. This Study task studied, evaluated and identified design concepts and technologies which minimized launch and in-space operations and optimized in-space vehicle propulsion system operability.

  19. Radiosynthesis and bioevaluation of [68Ga]-labeled 5,10,15,20-tetra(4-methylpyridyl)-porphyrin for possible application as a PET radiotracer for tumor imaging.

    PubMed

    Bhadwal, Mohini; Das, Tapas; Dev Sarma, Haladhar; Banerjee, Sharmila

    2015-02-01

    Porphyrins have inherent ability to localize preferentially in tumor lesions. Cationic porphyrins are readily water soluble and reported to exhibit strong DNA-binding capabilities. Therefore, attempt has been made to prepare a water soluble [(68)Ga]-labeled cationic porphyrin, viz., 5,10,15,20-tetra(4-methylpyridyl)porphyrin (TMP), and evaluate its potential as a positron emission tomography (PET) radiotracer for tumor imaging. The cationic porphyrin TMP was synthesized following a two-step procedure and subsequently radiolabeled with Ga-68, eluted from a commercial (68)Ge/(68)Ga generator. Purification of the [(68)Ga]-labeled porphyrin derivative was carried out using Sep-Pak(®) cartridges. The tumor-targeting potential of the [(68)Ga]-labeled-5,10,15,20-tetra(4-methylpyridyl)porphyrin was evaluated by biodistribution studies in Swiss mice bearing fibrosarcoma tumor. Under optimized reaction conditions, [(68)Ga]-labeled TMP was obtained with ~90 % radiochemical purity which was subsequently improved to >99 % after purification through Sep-Pak(®) cartridges. Biodistribution studies revealed high tumor uptake of the radiotracer within 30-min post-injection (6.47 ± 0.87 % of injected activity) and retention until the final 2 h post-administration (4.48 ± 1.11 % of injected activity) time point. The initial uptake observed in non-target organs cleared away with time resulting in gradually improving tumor/blood and tumor/muscle ratios. Preliminary bioevaluation studies indicated the potential of the radiolabeled porphyrin derivative for tumor imaging, and further detailed studies are warranted to evaluate the true potential of the developed radiotracer.

  20. Synthesis of carbon-11, fluorine-18, and nitrogen-13 labeled radiotracers for biomedical applications

    SciTech Connect

    Fowler, J.S.; Wolf, A.P.

    1981-01-01

    A number of reviews, many of them recent, have appeared on various aspects of /sup 11/C, /sup 18/F and /sup 13/N-labeled radiotracers. This monograph treats the topic principally from the standpoint of synthetic organic chemistry while keeping in perspective the necessity of integrating the organic chemistry with the design and ultimate application of the radiotracer. Where possible, recent examples from the literature of organic synthesis are introduced to suggest potentially new routes which may be applied to problems in labeling organic molecules with the short-lived positron emitters, carbon-11, fluorine-18, and nitrogen-13. The literature survey of carbon-11, fluorine-18 and nitrogen-13 labeled compounds presented are of particular value to scientists working in this field. Two appendices are also included to provide supplementary general references. A subject index concludes this volume.

  1. (68) Ga-labeled Ciprofloxacin Conjugates as Radiotracers for Targeting Bacterial Infection.

    PubMed

    Satpati, Drishty; Arjun, Chanda; Krishnamohan, Repaka; Samuel, Grace; Banerjee, Sharmila

    2016-05-01

    With an aim of developing a bacteria-specific molecular imaging agent, ciprofloxacin has been modified with a propylamine spacer and linked to two common bifunctional chelators, p-SCN-Bz-DOTA and p-SCN-Bz-NOTA. The two ciprofloxacin conjugates, CP-PA-SCN-Bz-DOTA (1) and CP-PA-SCN-Bz-NOTA (2), were radiolabeled with (68)Ga in >90% radiochemical yield and were moderately stable in vitro for 4 h. The efficacy of (68)Ga-1 and (68)Ga-2 has been investigated in vitro in Staphylococcus aureus cells where bacterial binding of the radiotracers (0.9-1.0% for (68)Ga-1 and 1.6-2.3% for (68)Ga-2) could not be blocked in the presence of excess amount of unlabeled ciprofloxacin. However, uptake of radiotracers in live bacterial cells was significantly higher (p < 0.01) than that in non-viable bacterial cells. Bacterial infection targeting efficacy of (68)Ga-1 and (68)Ga-2 was tested in vivo in rats where the infected muscle-to-inflamed muscle ((68)Ga-1: 2 ± 0.2, (68)Ga-2: 3 ± 0.5) and infected muscle-to-normal muscle ratios ((68)Ga-1: 3 ± 0.4, (68)Ga-2: 6.6 ± 0.8) were found to improve at 120 min p.i. Fast blood clearance and renal excretion was observed for both the radiotracers. The two (68)Ga-labeled infection targeting radiotracers could discriminate between bacterial infection and inflammation in vivo and are worthy of further detailed investigation as infection imaging agents at the clinical level. © 2015 John Wiley & Sons A/S.

  2. Cerenkov luminescence endoscopy: Improved molecular sensitivity with β--emitting radiotracers

    DOE PAGES

    Carpenter, Colin M.; Ma, Xiaowei; Liu, Hongguang; ...

    2014-10-09

    Cerenkov luminescence endoscopy (CLE) is an optical technique that captures the Cerenkov photons emitted from highly energetic moving charged particles (β+ or β$-$) and can be used to monitor the distribution of many clinically available radioactive probes. A main limitation of CLE is its limited sensitivity to small concentrations of radiotracer, especially when used with a light guide. We investigated the improvement in the sensitivity of CLE brought about by using a β$-$ radiotracer that improved Cerenkov signal due to both higher β-particle energy and lower γ noise in the imaging optics because of the lack of positron annihilation. Here,more » the signal-to-noise ratio (SNR) of 90Y was compared with that of 18F in both phantoms and small-animal tumor models. Sensitivity and noise characteristics were demonstrated using vials of activity both at the surface and beneath 1 cm of tissue. Rodent U87MG glioma xenograft models were imaged with radiotracers bound to arginine-glycine-aspartate (RGD) peptides to determine the SNR. As a result, γ noise from 18F was demonstrated by both an observed blurring across the field of view and a more pronounced fall-off with distance. A decreased γ background and increased energy of the β particles resulted in a 207-fold improvement in the sensitivity of 90Y compared with 18F in phantoms. 90Y-bound RGD peptide produced a higher tumor-to-background SNR than 18F in a mouse model. In conclusion, the use of 90Y for Cerenkov endoscopic imaging enabled superior results compared with an 18F radiotracer.« less

  3. Cerenkov luminescence endoscopy: Improved molecular sensitivity with β--emitting radiotracers

    SciTech Connect

    Carpenter, Colin M.; Ma, Xiaowei; Liu, Hongguang; Sun, Conroy; Pratx, Guillem; Wang, Jing; Gambhir, Sanjiv S.; Xing, Lei; Cheng, Zhen

    2014-10-09

    Cerenkov luminescence endoscopy (CLE) is an optical technique that captures the Cerenkov photons emitted from highly energetic moving charged particles (β+ or β$-$) and can be used to monitor the distribution of many clinically available radioactive probes. A main limitation of CLE is its limited sensitivity to small concentrations of radiotracer, especially when used with a light guide. We investigated the improvement in the sensitivity of CLE brought about by using a β$-$ radiotracer that improved Cerenkov signal due to both higher β-particle energy and lower γ noise in the imaging optics because of the lack of positron annihilation. Here, the signal-to-noise ratio (SNR) of 90Y was compared with that of 18F in both phantoms and small-animal tumor models. Sensitivity and noise characteristics were demonstrated using vials of activity both at the surface and beneath 1 cm of tissue. Rodent U87MG glioma xenograft models were imaged with radiotracers bound to arginine-glycine-aspartate (RGD) peptides to determine the SNR. As a result, γ noise from 18F was demonstrated by both an observed blurring across the field of view and a more pronounced fall-off with distance. A decreased γ background and increased energy of the β particles resulted in a 207-fold improvement in the sensitivity of 90Y compared with 18F in phantoms. 90Y-bound RGD peptide produced a higher tumor-to-background SNR than 18F in a mouse model. In conclusion, the use of 90Y for Cerenkov endoscopic imaging enabled superior results compared with an 18F radiotracer.

  4. XECT--a least squares curve fitting program for generalized radiotracer clearance model.

    PubMed

    Szczesny, S; Turczyński, B

    1991-01-01

    The program uses the joint Monte Carlo-Simplex algorithm for fitting the generalized, non-monoexponential model of externally detected decay of radiotracer activity in the tissue. The optimal values of the model parameters (together with the rate of the blood flow) are calculated. A table and plot of the experimental points and the fitted curve are generated. The program was written in Borland's Turbo Pascal 5.5 for the IBM PC XT/AT and compatible microcomputers.

  5. Residence time distribution measurements in a pilot-scale poison tank using radiotracer technique.

    PubMed

    Pant, H J; Goswami, Sunil; Samantray, J S; Sharma, V K; Maheshwari, N K

    2015-09-01

    Various types of systems are used to control the reactivity and shutting down of a nuclear reactor during emergency and routine shutdown operations. Injection of boron solution (borated water) into the core of a reactor is one of the commonly used methods during emergency operation. A pilot-scale poison tank was designed and fabricated to simulate injection of boron poison into the core of a reactor along with coolant water. In order to design a full-scale poison tank, it was desired to characterize flow of liquid from the tank. Residence time distribution (RTD) measurement and analysis was adopted to characterize the flow dynamics. Radiotracer technique was applied to measure RTD of aqueous phase in the tank using Bromine-82 as a radiotracer. RTD measurements were carried out with two different modes of operation of the tank and at different flow rates. In Mode-1, the radiotracer was instantaneously injected at the inlet and monitored at the outlet, whereas in Mode-2, the tank was filled with radiotracer and its concentration was measured at the outlet. From the measured RTD curves, mean residence times (MRTs), dead volume and fraction of liquid pumped in with time were determined. The treated RTD curves were modeled using suitable mathematical models. An axial dispersion model with high degree of backmixing was found suitable to describe flow when operated in Mode-1, whereas a tanks-in-series model with backmixing was found suitable to describe flow of the poison in the tank when operated in Mode-2. The results were utilized to scale-up and design a full-scale poison tank for a nuclear reactor.

  6. Cerenkov Luminescence Endoscopy: Improved Molecular Sensitivity with β−-Emitting Radiotracers

    PubMed Central

    Carpenter, Colin M.; Ma, Xiaowei; Liu, Hongguang; Sun, Conroy; Pratx, Guillem; Wang, Jing; Gambhir, Sanjiv S.; Xing, Lei; Cheng, Zhen

    2015-01-01

    Cerenkov luminescence endoscopy (CLE) is an optical technique that captures the Cerenkov photons emitted from highly energetic moving charged particles (β+ or β−) and can be used to monitor the distribution of many clinically available radioactive probes. A main limitation of CLE is its limited sensitivity to small concentrations of radiotracer, especially when used with a light guide. We investigated the improvement in the sensitivity of CLE brought about by using a β− radiotracer that improved Cerenkov signal due to both higher β-particle energy and lower γ noise in the imaging optics because of the lack of positron annihilation. Methods The signal-to-noise ratio (SNR) of 90Y was compared with that of 18F in both phantoms and small-animal tumor models. Sensitivity and noise characteristics were demonstrated using vials of activity both at the surface and beneath 1 cm of tissue. Rodent U87MG glioma xenograft models were imaged with radiotracers bound to arginine-glycine-aspartate (RGD) peptides to determine the SNR. Results γ noise from 18F was demonstrated by both an observed blurring across the field of view and a more pronounced fall-off with distance. A decreased γ background and increased energy of the β particles resulted in a 207-fold improvement in the sensitivity of 90Y compared with 18F in phantoms. 90Y-bound RGD peptide produced a higher tumor-to-background SNR than 18F in a mouse model. Conclusion The use of 90Y for Cerenkov endoscopic imaging enabled superior results compared with an 18F radiotracer. PMID:25300598

  7. Radiation dosimetry and biodistribution of the translocator protein radiotracer [(11)C]DAA1106 determined with PET/CT in healthy human volunteers.

    PubMed

    Brody, Arthur L; Okita, Kyoji; Shieh, Jennifer; Liang, Lidia; Hubert, Robert; Mamoun, Michael; Farahi, Judah; Mandelkern, Mark A

    2014-01-01

    When microglia become activated (an integral part of neuroinflammation), cellular morphology changes and expression of translocator protein (TSPO) 18 kDa is increased. Over the past several years, [(11)C]DAA1106 has emerged as a reliable radiotracer for labeling TSPO with high affinity during positron emission tomography (PET) scanning. While [(11)C]DAA1106 PET scanning has been used in several research studies, a radiation dosimetry study of this radiotracer in humans has not yet been published. Twelve healthy participants underwent full body dynamic [(11)C]DAA1106 PET scanning, with 8 sequential whole body scans (approximately 12 bed positions each), following a single injection. Regions of interest were drawn manually, and time activity curves (TACs) were obtained for 15 organs. OLINDA/EXM 1.1 was used to compute radiation absorbed doses to the target organs, as well as effective dose (ED) and effective dose equivalent (EDE). The ED and EDE were 4.06 ± 0.58 μSv/MBq and 5.89 ± 0.83 μSv/MBq, respectively. The highest absorbed doses were to the heart wall, kidney, liver, pancreas, and spleen. TACs revealed that peak dose rates are during the first scan (at 6 min) for all organs other than the urinary bladder wall, which had its peak dose rate during the fourth scan (at 30 min). The recently developed radiotracer [(11)C]DAA1106 has its EDE and target-organ absorbed dose such that, for a single administration, its radiation dosimetry is well within the U.S. FDA guidelines for basic research studies in adults. This dose level implies that the dosimetry for multiple [(11)C]DAA1106 scans within a given year also falls within FDA guidelines, and this favorable property makes this radiotracer suitable for examining microglial activation repeatedly over time, which may in the future be useful for longitudinal tracking of disease progression and monitoring of therapy response in conditions marked by neuroinflammation (e.g., head trauma and multiple sclerosis). Published

  8. Hypersonic code efficiency and validation studies

    NASA Technical Reports Server (NTRS)

    Bennett, Bradford C.

    1992-01-01

    Renewed interest in hypersonic and supersonic flows spurred the development of the Compressible Navier-Stokes (CNS) code. Originally developed for external flows, CNS was modified to enable it to also be applied to internal high speed flows. In the initial phase of this study CNS was applied to both internal flow applications and fellow researchers were taught to run CNS. The second phase of this research was the development of surface grids over various aircraft configurations for the High Speed Research Program (HSRP). The complex nature of these configurations required the development of improved surface grid generation techniques. A significant portion of the grid generation effort was devoted to testing and recommending modifications to early versions of the S3D surface grid generation code.

  9. Stress and efficiency studies in EFG

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The goals of this program were: (1) to define minimum stress configurations for silicon sheet growth at high speeds; (2) to quantify dislocation electrical activity and their limits on minority carrier diffusion length in deformed silicon; and (3) to study reasons for degradation of lifetime with increases in doping level in edge-defined film-fed growth (EFG) materials. A finite element model was developed for calculating residual stress with plastic deformation. A finite element model was verified for EFG control variable relationships to temperature field of the sheet to permit prediction of profiles and stresses encountered in EFG systems. A residual stress measurement technique was developed for finite size EFG material blanks using shadow Moire interferometry. Transient creep response of silicon was investigated in the temperature range between 800 and 1400 C in strain and strain regimes of interest in stress analysis of sheet growth. Quantitative relationships were established between minority carrier diffusion length and dislocation densities using Electron Beam Induced Current (EBIC) measurement in FZ silicon deformed in four point bending tests.

  10. Synthesis and Biological Evaluation of Thiophene-Based Cannabinoid Receptor Type 2 Radiotracers for PET Imaging

    PubMed Central

    Haider, Ahmed; Müller Herde, Adrienne; Slavik, Roger; Weber, Markus; Mugnaini, Claudia; Ligresti, Alessia; Schibli, Roger; Mu, Linjing; Mensah Ametamey, Simon

    2016-01-01

    Over the past two decades, our understanding of the endocannabinoid system has greatly improved due to the wealth of results obtained from exploratory studies. Currently, two cannabinoid receptor subtypes have been well-characterized. The cannabinoid receptor type 1 (CB1) is widely expressed in the central nervous system, while the levels of the cannabinoid receptor type 2 (CB2) in the brain and spinal cord of healthy individuals are relatively low. However, recent studies demonstrated a CB2 upregulation on activated microglia upon neuroinflammation, an indicator of neurodegeneration. Our research group aims to develop a suitable positron emission tomography (PET) tracer to visualize the CB2 receptor in patients suffering from neurodegenerative diseases. Herein we report two novel thiophene-based 11C-labeled PET ligands designated [11C]AAT-015 and [11C]AAT-778. The reference compounds were synthesized using Gewald reaction conditions to obtain the aminothiophene intermediates, followed by amide formation. Saponification of the esters provided their corresponding precursors. Binding affinity studies revealed Ki-values of 3.3 ± 0.5 nM (CB2) and 1.0 ± 0.2 μM (CB1) for AAT-015. AAT-778 showed similar Ki-values of 4.3 ± 0.7 nM (CB2) and 1.1 ± 0.1 μM (CB1). Radiosynthesis was carried out under basic conditions using [11C]iodomethane as methylating agent. After semi-preparative HPLC purification both radiolabeled compounds were obtained in 99% radiochemical purity and the radiochemical yields ranged from 12 to 37%. Specific activity was between 96 and 449 GBq/μmol for both tracers. In order to demonstrate CB2 specificity of [11C]AAT-015 and [11C]AAT-778, we carried out autoradiography studies using CB2-positive mouse/rat spleen tissues. The obtained results revealed unspecific binding in spleen tissue that was not blocked by an excess of CB2-specific ligand GW402833. For in vivo analysis, [11C]AAT-015 was administered to healthy rats via tail-vein injection

  11. Synthesis and Biological Evaluation of Thiophene-Based Cannabinoid Receptor Type 2 Radiotracers for PET Imaging.

    PubMed

    Haider, Ahmed; Müller Herde, Adrienne; Slavik, Roger; Weber, Markus; Mugnaini, Claudia; Ligresti, Alessia; Schibli, Roger; Mu, Linjing; Mensah Ametamey, Simon

    2016-01-01

    Over the past two decades, our understanding of the endocannabinoid system has greatly improved due to the wealth of results obtained from exploratory studies. Currently, two cannabinoid receptor subtypes have been well-characterized. The cannabinoid receptor type 1 (CB1) is widely expressed in the central nervous system, while the levels of the cannabinoid receptor type 2 (CB2) in the brain and spinal cord of healthy individuals are relatively low. However, recent studies demonstrated a CB2 upregulation on activated microglia upon neuroinflammation, an indicator of neurodegeneration. Our research group aims to develop a suitable positron emission tomography (PET) tracer to visualize the CB2 receptor in patients suffering from neurodegenerative diseases. Herein we report two novel thiophene-based (11)C-labeled PET ligands designated [(11)C]AAT-015 and [(11)C]AAT-778. The reference compounds were synthesized using Gewald reaction conditions to obtain the aminothiophene intermediates, followed by amide formation. Saponification of the esters provided their corresponding precursors. Binding affinity studies revealed Ki-values of 3.3 ± 0.5 nM (CB2) and 1.0 ± 0.2 μM (CB1) for AAT-015. AAT-778 showed similar Ki-values of 4.3 ± 0.7 nM (CB2) and 1.1 ± 0.1 μM (CB1). Radiosynthesis was carried out under basic conditions using [(11)C]iodomethane as methylating agent. After semi-preparative HPLC purification both radiolabeled compounds were obtained in 99% radiochemical purity and the radiochemical yields ranged from 12 to 37%. Specific activity was between 96 and 449 GBq/μmol for both tracers. In order to demonstrate CB2 specificity of [(11)C]AAT-015 and [(11)C]AAT-778, we carried out autoradiography studies using CB2-positive mouse/rat spleen tissues. The obtained results revealed unspecific binding in spleen tissue that was not blocked by an excess of CB2-specific ligand GW402833. For in vivo analysis, [(11)C]AAT-015 was administered to healthy rats via tail

  12. Coeur d'Alene Tribe Energy Efficiency Feasibility Study

    SciTech Connect

    Allgood, Tiffany L.; Sorter, Andy

    2014-09-01

    The Coeur d'Alene Tribe's Energy Efficiency Feasibility Study (EEFS) is the culminating document that compiles the energy efficiency and building performance assessment and project prioritization process completed on 36 Tribally owned and operated facilities within Tribal lands. The EEFS contains sections on initial findings, utility billing analyses, energy conservation measures and prioritization and funding sources and strategies for energy project implementation.

  13. Preclinical radiation dosimetry for the novel SV2A radiotracer [18F]UCB-H

    PubMed Central

    2013-01-01

    Background [18F]UCB-H was developed as a novel radiotracer with a high affinity for synaptic vesicle protein 2A, the binding site for the antiepileptic levetiracetam. The objectives of this study were to evaluate the radiation dosimetry of [18F]UCB-H in a preclinical trial and to determine the maximum injectable dose according to guidelines for human biomedical research. The radiation dosimetry was derived by organ harvesting and dynamic micro positron emission tomography (PET) imaging in mice, and the results of both methods were compared. Methods Twenty-four male C57BL-6 mice were injected with 6.96 ± 0.81 MBq of [18F]UCB-H, and the biodistribution was determined by organ harvesting at 2, 5, 10, 30, 60, and 120 min (n = 4 for each time point). Dynamic microPET imaging was performed on five male C57BL-6 mice after the injection of 9.19 ± 3.40 MBq of [18F]UCB-H. A theoretical dynamic bladder model was applied to simulate urinary excretion. Human radiation dose estimates were derived from animal data using the International Commission on Radiological Protection 103 tissue weighting factors. Results Based on organ harvesting, the urinary bladder wall, liver and brain received the highest radiation dose with a resulting effective dose of 1.88E-02 mSv/MBq. Based on dynamic imaging an effective dose of 1.86E-02 mSv/MBq was calculated, with the urinary bladder wall and liver (brain was not in the imaging field of view) receiving the highest radiation. Conclusions This first preclinical dosimetry study of [18F]UCB-H showed that the tracer meets the standard criteria for radiation exposure in clinical studies. The dose-limiting organ based on US Food and Drug Administration (FDA) and European guidelines was the urinary bladder wall for FDA and the effective dose for Europe with a maximum injectable single dose of approximately 325 MBq was calculated. Although microPET imaging showed significant deviations from organ harvesting, the Pearson’s correlation coefficient

  14. Microfluidic reactor for the radiosynthesis of PET radiotracers.

    PubMed

    Gillies, J M; Prenant, C; Chimon, G N; Smethurst, G J; Perrie, W; Hamblett, I; Dekker, B; Zweit, J

    2006-03-01

    Here we show the first application of a microfabricated reaction system to PET radiochemistry, we term "microfluidic PET". The short half-life of the positron emitting isotopes and the trace chemical quantities used in radiolabelling make PET radiochemistry amenable to miniaturisation. Microfluidic technologies are capable of controlling and transferring tiny quantities of liquids which allow chemical and biochemical assays to be integrated and carried out on a small scale. Such technologies provide distinct advantages over current methods of PET radiochemical synthesis. To demonstrate "proof of principle" we have investigated the radiohalogenation of small and large molecular weight molecules using the microfluidic device. These reactions involved the direct radioiodination of the apoptosis marker Annexin V using iodine-124, the indirect radioiodination of the anti-cancer drug doxorubicin from a tin-butyl precursor and the radiosynthesis of 2-[(18)F]FDG from a mannose triflate precursor and fluorine-18 and hence provide a test bed for microfluidic reactions. We demonstrate the rapid radioiodination of the protein Annexin V (40% radiochemical yield within 1 min) and the rapid radiofluorination of 2-[(18)F]FDG (60% radiochemical yield within 4s) using a polymer microreactor chip. Chromatographic analysis showed that the labelling efficiency of the unoptimised microfluidic chip is comparable to conventional PET radiolabelling reactions.

  15. Comparison of three devices for automated infusion of positron-emitting radiotracers.

    PubMed

    Miyaji, Noriaki; Miwa, Kenta; Wagatsuma, Kei; Murata, Taisuke; Umeda, Takuro; Terauchi, Takashi; Koizumi, Mitsuru

    2017-03-09

    The administration accuracy and precision of automated infusion device for positron-emitting radiotracer is directly associated with bias and variance in standardized uptake values (SUV) of (18)F-FDG PET/CT. Therefore, the accuracy of such devices must be confirmed and calibrated at locations where they are used. The present study aimed to validate the administration accuracy of three automated infusion devices for quantitative PET assessment. Methods: Temporal variations as well as variations in radioactive concentrations and dispensed volumes of (18)F-FDG were determined for the M-130, the AI-300 (both Sumitomo Heavy Industries Ltd., Japan), and the UG-05 (Universal Giken Co. Ltd., Japan) automated infusion devices. The total test dispensed volumes were 25, 20 and 18.5 mL, respectively. A reference value was generated by measuring amounts of radioactivity using a standard dose calibrator. Administration accuracy was validated according to the criteria of the Japanese Society of Nuclear Medicine (JSNM). Results: Temporal variation in the M-130 and UG-05 for specified 185 MBq was a relatively stable in the range -1.60 to 0.92% and 1.16 to 5.35%, respectively, whereas that in the AI-300 was -0.55 to 8.68%. For M-130 and UG-05, the difference between measured and reference value was in the range -5 to 5%. The values measured by the AI-300 deviated from the reference values by a maximum of 30%, which depends on radioactive concentration and dispensed volume of (18)F-FDG. Conclusion: The administration accuracy of the AI-300 varied considerably under different conditions, but a software update might somewhat improve this. Our findings indicate that dispensed volumes of (18)F-FDG should be carefully considered when the radioactive concentration is high. Administration accuracy should be regularly confirmed at each location to maintain the quality of quantitative PET assessment. The present study provides useful information about how to confirm the administration

  16. The Water Efficiency Paradox, a study of Central Asia

    NASA Astrophysics Data System (ADS)

    Merks, Joreen; Bastiaanssen, Wim

    2017-04-01

    Water scarcity is a rapidly growing concern in the semi-arid areas of Central Asia. Water savings and efficiency improvement programs are promoted as a possibility to save the Aral Sea. The Aral Seas lost 92% of its volume between 1960 and 2009. Projects on rehabilitating the Aral Sea and increasing the efficiency of water use in the irrigation sector are, however, not making progress. In Central Asia, 90% of the water withdrawal is allocated to agriculture. Irrigation efficiency programs often disregard the downstream connectivity of the water flow path. Not all water being applied is consumed by crop evapotranspiration and in fact an equally great portion of water returns back into the river basin system and is reused downstream. This cascade effect implies that results in one location can induce a scarcity of water in another location. The cascade effect in the Syr Darya has been studied by means of the Aral Sea Basin Management Model (ASBMM) designed by SIC-ICWC and remote sensing data produced by UNESCO-IHE. We will demonstrate the impact of increasing irrigation efficiency locally on the overall water consumption in the basin. We will show that efficiency increases with larger areas, and that there are caps to the maximum efficiency at basin scale. Increasing efficiency is thus not self-evident. Classical solutions on promoting increase of efficiency and water savings are therefore outdated and misleads stakeholders. We will look into the misconceptions and challenges in the communication between researchers and policy makers regarding increasing efficiency.

  17. In vivo imaging of reactive oxygen species in mouse brain by using [3H]hydromethidine as a potential radical trapping radiotracer.

    PubMed

    Abe, Kohji; Takai, Nozomi; Fukumoto, Kazumi; Imamoto, Natsumi; Tonomura, Misato; Ito, Miwa; Kanegawa, Naoki; Sakai, Katsunori; Morimoto, Kenji; Todoroki, Kenichiro; Inoue, Osamu

    2014-12-01

    To assess reactive oxygen species (ROS) production by detecting the fluorescent oxidation product, hydroethidine has been used extensively. The present study was undertaken to evaluate the potential of the hydroethidine derivative as a radiotracer to measure in vivo brain ROS production. [(3)H]-labeled N-methyl-2,3-diamino-6-phenyl-dihydrophenanthridine ([(3)H]Hydromethidine) was synthesized, and evaluated using in vitro radical-induced oxidization and in vivo brain ROS production model. In vitro studies have indicated that [(3)H]Hydromethidine is converted to oxidized products by a superoxide radical (O(2)(•)-) and a hydroxyl radical (OH(•)-) but not hydrogen peroxide (H(2)O(2)). In vivo whole-body distribution study showed that [(3)H]Hydromethidine rapidly penetrated the brain and then was washed out in normal mice. Microinjection of sodium nitroprusside (SNP) into the brain was performed to produce ROS such as OH(•)- via Fenton reaction. A significant accumulation of radioactivity immediately after [(3)H]Hydromethidine injection was seen in the side of the brain treated with SNP (5 and 20 nmol) compared with that in the contralateral side. These results indicated that [(3)H]Hydromethidine freely penetrated into the brain where it was rapidly converted to oxidized forms, which were trapped there in response to the production of ROS. Thus, [(3)H]Hydromethidine should be useful as a radical trapping radiotracer in the brain.

  18. Strategies for Energy Efficient Remodeling: SEER 2003 Case Study Report

    SciTech Connect

    2004-11-01

    The goal of the Strategies for Energy Efficiency in Remodeling (SEER) project is to provide information, based on research and case studies, to remodelers and consumers about opportunities to increase home energy performance.

  19. In Vivo Imaging of Experimental Melanoma Tumors using the Novel Radiotracer (68)Ga-NODAGA-Procainamide (PCA).

    PubMed

    Kertész, István; Vida, András; Nagy, Gábor; Emri, Miklós; Farkas, Antal; Kis, Adrienn; Angyal, János; Dénes, Noémi; Szabó, Judit P; Kovács, Tünde; Bai, Péter; Trencsényi, György

    2017-01-01

    The most aggressive form of skin cancer is the malignant melanoma. Because of its high metastatic potential the early detection of primary melanoma tumors and metastases using non-invasive PET imaging determines the outcome of the disease. Previous studies have already shown that benzamide derivatives, such as procainamide (PCA) specifically bind to melanin pigment. The aim of this study was to synthesize and investigate the melanin specificity of the novel (68)Ga-labeled NODAGA-PCA molecule in vitro and in vivo using PET techniques. Procainamide (PCA) was conjugated with NODAGA chelator and was labeled with Ga-68 ((68)Ga-NODAGA-PCA). The melanin specificity of (68)Ga-NODAGA-PCA was tested in vitro, ex vivo and in vivo using melanotic B16-F10 and amelanotic Melur melanoma cell lines. By subcutaneous and intravenous injection of melanoma cells tumor-bearing mice were prepared, on which biodistribution studies and small animal PET/CT scans were performed for (68)Ga-NODAGA-PCA and (18)FDG tracers. (68)Ga-NODAGA-PCA was produced with high specific activity (14.9±3.9 GBq/µmol) and with excellent radiochemical purity (98%<), at all cases. In vitro experiments showed that (68)Ga-NODAGA-PCA uptake of B16-F10 cells was significantly (p≤0.01) higher than Melur cells. Ex vivo biodistribution and in vivo PET/CT studies using subcutaneous and metastatic tumor models showed significantly (p≤0.01) higher (68)Ga-NODAGA-PCA uptake in B16-F10 primary tumors and lung metastases in comparison with amelanotic Melur tumors. In experiments where (18)FDG and (68)Ga-NODAGA-PCA uptake of B16-F10 tumors was compared, we found that the tumor-to-muscle (T/M) and tumor-to-lung (T/L) ratios were significantly (p≤0.05 and p≤0.01) higher using (68)Ga-NODAGA-PCA than the (18)FDG accumulation. Our novel radiotracer (68)Ga-NODAGA-PCA showed specific binding to the melanin producing experimental melanoma tumors. Therefore, (68)Ga-NODAGA-PCA is a suitable diagnostic radiotracer for the

  20. In Vivo Imaging of Experimental Melanoma Tumors using the Novel Radiotracer 68Ga-NODAGA-Procainamide (PCA)

    PubMed Central

    Kertész, István; Vida, András; Nagy, Gábor; Emri, Miklós; Farkas, Antal; Kis, Adrienn; Angyal, János; Dénes, Noémi; Szabó, Judit P.; Kovács, Tünde; Bai, Péter; Trencsényi, György

    2017-01-01

    Purpose: The most aggressive form of skin cancer is the malignant melanoma. Because of its high metastatic potential the early detection of primary melanoma tumors and metastases using non-invasive PET imaging determines the outcome of the disease. Previous studies have already shown that benzamide derivatives, such as procainamide (PCA) specifically bind to melanin pigment. The aim of this study was to synthesize and investigate the melanin specificity of the novel 68Ga-labeled NODAGA-PCA molecule in vitro and in vivo using PET techniques. Methods: Procainamide (PCA) was conjugated with NODAGA chelator and was labeled with Ga-68 (68Ga-NODAGA-PCA). The melanin specificity of 68Ga-NODAGA-PCA was tested in vitro, ex vivo and in vivo using melanotic B16-F10 and amelanotic Melur melanoma cell lines. By subcutaneous and intravenous injection of melanoma cells tumor-bearing mice were prepared, on which biodistribution studies and small animal PET/CT scans were performed for 68Ga-NODAGA-PCA and 18FDG tracers. Results: 68Ga-NODAGA-PCA was produced with high specific activity (14.9±3.9 GBq/µmol) and with excellent radiochemical purity (98%<), at all cases. In vitro experiments showed that 68Ga-NODAGA-PCA uptake of B16-F10 cells was significantly (p≤0.01) higher than Melur cells. Ex vivo biodistribution and in vivo PET/CT studies using subcutaneous and metastatic tumor models showed significantly (p≤0.01) higher 68Ga-NODAGA-PCA uptake in B16-F10 primary tumors and lung metastases in comparison with amelanotic Melur tumors. In experiments where 18FDG and 68Ga-NODAGA-PCA uptake of B16-F10 tumors was compared, we found that the tumor-to-muscle (T/M) and tumor-to-lung (T/L) ratios were significantly (p≤0.05 and p≤0.01) higher using 68Ga-NODAGA-PCA than the 18FDG accumulation. Conclusion: Our novel radiotracer 68Ga-NODAGA-PCA showed specific binding to the melanin producing experimental melanoma tumors. Therefore, 68Ga-NODAGA-PCA is a suitable diagnostic radiotracer for

  1. Distractor Efficiency: A Study into the Nature of Distractor Efficiency in Foreign Language Testing.

    ERIC Educational Resources Information Center

    Goodrich, Hubbard C.

    The aim of the research in question was to investigate the efficiency of various classes of distractors used in multiple-choice vocabulary question testing. Much of the quality of multiple-choice questions relies on the extent to which incorrect choices tempt the less proficient student. The study selected 8 classes of distractors and attempted to…

  2. Investigation of hydrodynamic behaviour of membranes using radiotracer techniques

    NASA Astrophysics Data System (ADS)

    Miskiewicz, A.; Zakrzewska-Trznadel, G.

    2013-05-01

    The aim of the work was to study membrane devices using short-lived radioisotopes like Ba-137m and Ga-68 as tracers. These radioisotopes were obtained from radionuclide generators: Cs-137/Ba-137m and Ge-68/Ga-68. The first radionuclide, namely Ba-137m with a half-life of 2.55 minutes was applied as a liquid phase tracer for studying hydrodynamic conditions inside the membrane apparatus. The membrane module with ceramic membranes was tested by using Ba-137m. The experiments showed that this radionuclide with a short half-life is a perfect tracer for liquid phase, whereas Ga-68 with longer half-life equal to 68 minutes was considered as a solid phase (bentonite) tracer. Ga-68 was used to gain more knowledge about the phenomena occurring in the membrane boundary layer. After kinetic studies of isotope adsorption into the carrier material, the growth rate of the deposit layer as well as deposit's thickness on the flat-sheet membrane were studied. The influence of such process parameters like pressure, linear velocity of liquid and feed concentration on formation of the bentonite layer on the membrane surface was studied.

  3. Applications of Beta Particle Detection for Synthesis and Usage of Radiotracers Developed for Positron Emission Tomography

    NASA Astrophysics Data System (ADS)

    Dooraghi, Alex Abreu

    Positron Emission Tomography (PET) is a noninvasive molecular imaging tool that requires the use of a radioactive compound or radiotracer which targets a molecular pathway of interest. We have developed and employed three beta particle radiation detection systems to advance PET. Specifically, the goals of these systems are to: 1. Automate dispensing of solutions containing a positron emitting isotope. 2. Monitor radioactivity on-chip during synthesis of a positron emitting radiotracer. 3. Assay cellular uptake on-chip of a positron emitting radiotracer. Automated protocols for measuring and dispensing solutions containing radioisotopes are essential not only for providing an optimum environment for radiation workers, but also to ensure a quantitatively accurate workflow. For the first project, we describe the development and performance of a system for automated radioactivity distribution of beta particle emitting radioisotopes such as fluorine-18 (F-18). Key to the system is a radiation detector in-line with a peristaltic pump. The system demonstrates volume accuracy within 5 % for volumes of 20 muL or greater. When considering volumes of 20 muL or greater, delivered radioactivity is in agreement with the requested radioactivity as measured with the dose calibrator. The integration of the detector and pump leads to a flexible system that can accurately dispense solutions containing F-18 in radioactivity concentrations directly produced from a cyclotron (~ 0.1-1 mCi/muL), to low activity concentrations intended for preclinical mouse scans (~ 1-10 muCi/muL), and anywhere in between. Electrowetting on dielectric (EWOD) is an attractive microfluidic platform for batch synthesis of PET radiotracers. Visualization of radioisotopes on-chip is critical for synthesis optimization and technological development. For the second project, we describe the development and performance of a Cerenkov/real-time imaging system for PET radiotracer synthesis on EWOD. We also investigate

  4. PET Radiotracers for Imaging the Proliferation Status of Breast Tumors

    DTIC Science & Technology

    2004-12-01

    that are antagonists of the dopamine D3 protein coupled receptor protein superfamily. Based receptor.t ’ 2 This interest was largely generated by the...receptor- based biomarker of of proliferation in breast tumor cells growing both in vitro and in vivo. During the second year of the three-year IDEA project...nucleoside- based approach that has been hypothesized to measure the proliferation in solid tumors. These studies were funded in part through the NIH grant CA1

  5. Tactics for preclinical validation of receptor-binding radiotracers.

    PubMed

    Lever, Susan Z; Fan, Kuo-Hsien; Lever, John R

    2017-01-01

    Aspects of radiopharmaceutical development are illustrated through preclinical studies of [(125)I]-(E)-1-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-4-(iodoallyl)piperazine ([(125)I]-E-IA-BF-PE-PIPZE), a radioligand for sigma-1 (σ1) receptors, coupled with examples from the recent literature. Findings are compared to those previously observed for [(125)I]-(E)-1-(2-(2,3-dimethoxy-5-yl)ethyl)-4-(iodoallyl)piperazine ([(125)I]-E-IA-DM-PE-PIPZE). Syntheses of E-IA-BF-PE-PIPZE and [(125)I]-E-IA-BF-PE-PIPZE were accomplished by standard methods. In vitro receptor binding studies and autoradiography were performed, and binding potential was predicted. Measurements of lipophilicity and protein binding were obtained. In vivo studies were conducted in mice to evaluate radioligand stability, as well as specific binding to σ1 sites in brain, brain regions and peripheral organs in the presence and absence of potential blockers. E-IA-BF-PE-PIPZE exhibited high affinity and selectivity for σ1 receptors (Ki = 0.43 ± 0.03 nM, σ2/σ1 = 173). [(125)I]-E-IA-BF-PE-PIPZE was prepared in good yield and purity, with high specific activity. Radioligand binding provided dissociation (koff) and association (kon) rate constants, along with a measured Kd of 0.24 ± 0.01 nM and Bmax of 472 ± 13 fmol/mg protein. The radioligand proved suitable for quantitative autoradiography in vitro using brain sections. Moderate lipophilicity, Log D7.4 2.69 ± 0.28, was determined, and protein binding was 71 ± 0.3%. In vivo, high initial whole brain uptake, >6% injected dose/g, cleared slowly over 24 h. Specific binding represented 75% to 93% of total binding from 15 min to 24 h. Findings were confirmed and extended by regional brain biodistribution. Radiometabolites were not observed in brain (1%). Substitution of dihydrobenzofuranylethyl for dimethoxyphenethyl increased radioligand affinity for σ1 receptors by 16-fold. While high specific binding to σ1 receptors was observed for both radioligands in vivo

  6. Transmutation products may influence radiotracer diffusion rates in an ionic solid.

    PubMed

    Wei, G C; Wuensch, B J

    1977-07-08

    An inherent aspect of radiotracer diffusion is that alpha, beta(+), or beta(-) emission produces a daughter element of different ionization state. This process must either cause a change in the vacancy concentrations or create space charge, depending on the effectiveness of the internal sources or sinks. Four coupled equations established to model the kinetics, when solved by numerical methods, predict that the apparent tracer diffusion rate may easily be in error by a factor of 2 or 3 and, under certain conditions, by as much as an order of magnitude.

  7. Ibuprofen induces reduction of the proliferation-seeking radiotracer 99mTc-(V)DMSA uptake in severe epithelial breast hyperplasia without atypia.

    PubMed

    Papantoniou, Vassilios; Tsaroucha, Angeliki; Valsamaki, Pipitsa; Tsiouris, Spyridon; Sotiropoulou, Evangelia; Karianos, Theodore; Marinopoulos, Spyridon; Fothiadaki, Athina; Sotiropoulou, Maria; Archontaki, Aikaterini; Syrgiannis, Konstantinos; Dimitrakakis, Konstantinos; Antsaklis, Aris

    2010-10-01

    The purpose of this study was to investigate if ibuprofen intake can influence mammary uptake of the proliferation-seeking radiotracer technetium 99m-pentavalent dimercaptosuccinic acid (99mTc-(V)DMSA) in women with severe epithelial and atypical epithelial breast hyperplasia. Eight patients with histologically confirmed severe epithelial breast hyperplasia with (n  =  4) and without atypia (n  =  4) were submitted prospectively to 99mTc-(V)DMSA scintimammography before and after a 4-week course of 400 mg ibuprofen daily oral intake. Lesion to background ratios 60 minutes postinjection were calculated and compared (t-test) before and after ibuprofen administration. Prior to ibuprofen, the patients with severe epithelial hyperplasia displayed a significantly higher 99mTc-(V)DMSA uptake ratio compared to those with atypical epithelial hyperplasia (2.40 ± 0.32 vs 1.67 ± 0.09, respectively; p  =  .003). They also exhibited a more substantial percent decline in tracer uptake postibuprofen compared to women with atypical epithelial hyperplasia (62.0 ± 7.1 vs 15.0 ± 0.2, respectively; p  =  .001). Ibuprofen induces significant uptake reduction of the proliferation-seeking radiotracer 99mTc-(V)DMSA in severe epithelial breast hyperplasia without atypia. This agent could therefore constitute a potential imaging tool for monitoring chemoprophylaxis effectiveness in women at the early stages of malignant transformation.

  8. A 1-methyl-4-piperidinyl cytectrene carboxylate labeled by the technetium 99m, a radiotracer for rat brain acetylcholinesterase activity.

    PubMed

    Mejri, Najoua; Barhoumi, Chokri; Trabelsi, Moez; Mekni, Abdelkader; Said, Nadia Malek; Saidi, Mouldi

    2010-02-01

    Alzheimer's disease (AD) is a degenerative neurological disorder that causes progressive and irreversible loss of connections between brain cells and loss of mental functions. Clinical and postmortem studies show that the biochemical changes in brains of AD patients include decrease in acetylcholinesterase (AChE) activity. Our aim was to study AChE activity using piperidinyl ester labelled with technetium-99m. In vivo and in vitro studies demonstrated that labelled piperidinyl ester was a substrate for AChE. The hydrolytic rate of this substrate was measured and the specificity was evaluated using the inhibitor BW284c51. The rhenium analogues of the technetium-labelled substrate were used to determine the affinity constant (K(m)) and the maximum reaction velocity (V(max)) because of the high specific activity of technetium. The high hydrolytic rate and high specificity of the substrate for AChE make it suitable as an in vivo radiotracer for studying AChE activity in the brain.

  9. A comparative evaluation of the dopamine D(2/3) agonist radiotracer [11C](-)-N-propyl-norapomorphine and antagonist [11C]raclopride to measure amphetamine-induced dopamine release in the human striatum.

    PubMed

    Narendran, Rajesh; Mason, N Scott; Laymon, Charles M; Lopresti, Brian J; Velasquez, Natalie D; May, Maureen A; Kendro, Steve; Martinez, Diana; Mathis, Chester A; Frankle, W Gordon

    2010-05-01

    (-)-N-Propyl-norapomorphine (NPA) is a full dopamine D(2/3) receptor agonist, and [(11)C]NPA is a suitable radiotracer to image D(2/3) receptors configured in a state of high affinity for agonists with positron emission tomography (PET). In this study, the vulnerability of the in vivo binding of [11C]NPA to acute fluctuation in synaptic dopamine was assessed with PET in healthy humans and compared with that of the reference D(2/3) receptor antagonist radiotracer [11C]raclopride. Ten subjects (eight females and two males) were studied on two separate days, a minimum of 1 week apart, both with [11C]raclopride and [11C]NPA at baseline and after the administration of 0.5 mg x kg(-1) oral d-amphetamine. Kinetic modeling with an arterial input function was used to derive the binding potential relative to nonspecific uptake (BPND) in the ventral striatum (VST), caudate (CAD), and putamen (PUT). [11C]Raclopride BPND was significantly reduced by 9.7 +/- 4.4, 8.4 +/- 4.2, and 14.7 +/- 4.8% after amphetamine administration in the VST, CAD, and PUT. [11C]NPA BPND was also reduced significantly, by 16.0 +/- 7.0, 16.1 +/- 6.1, and 21.9 +/- 4.9% after the same dose of amphetamine in the VST, CAD, and PUT. Although these results suggest that [11C]NPA is more vulnerable to endogenous competition by dopamine compared with [11C]raclopride by a factor of 1.49 to 1.90, the same data for a related outcome measure, binding potential relative to plasma concentration, was not significant. Nevertheless, these data add to the growing literature that suggests D(2/3) agonist radiotracers are more vulnerable to endogenous competition by dopamine than existing D(2/3) antagonist radiotracers.

  10. A Study of Visual Efficiency Necessary for Beginning Reading.

    ERIC Educational Resources Information Center

    Young, Beverly S.; And Others

    A study was conducted to determine if there were significant differences in vision between beginning readers who learn to read easily and those who learn with difficulty (dyslexics). In addition, the study examined the mean of the high achievers (rather than expert opinion) to discover the degree to which visual efficiency was normally needed for…

  11. Managing Lymphoma with Non-FDG Radiotracers: Current Clinical and Preclinical Applications

    PubMed Central

    Kong, Fan-Lin; Ford, Richard J.; Yang, David J.

    2013-01-01

    Nuclear medicine imaging modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have played a prominent role in lymphoma management. PET with [18F]Fluoro-2-deoxy-D-glucose (FDG) is the most commonly used tool for lymphoma imaging. However, FDG-PET has several limitations that give the false positive or false negative diagnosis of lymphoma. Therefore, development of new radiotracers with higher sensitivity, specificity, and different uptake mechanism is in great demand in the management of lymphoma. This paper reviews non-FDG radiopharmaceuticals that have been applied for PET and SPECT imaging in patients with different types of lymphoma, with attention to diagnosis, staging, therapy response assessment, and surveillance for disease relapse. In addition, we introduce three radiolabeled anti-CD20 antibodies for radioimmunotherapy, which is another important arm for lymphoma treatment and management. Finally, the relatively promising radiotracers that are currently under preclinical development are also discussed in this paper. PMID:23841079

  12. Radiotracer Injection Into the Catheter Balloon: A Subtle Pitfall Which Can Be Overlooked in Direct Radionuclide Cystography.

    PubMed

    Massoudi, Toktam; Shayegani, Hamed; Sadeghi, Ramin

    2017-04-01

    We reported a 4-year-old girl with history of bilateral vesicoureteral reflux who underwent direct radionuclide cystography in our department. Radiotracer was mistakenly injected in the catheter balloon. The filling phase showed no change in the bladder volume, and the catheter balloon was apparent as an intense activity in the base of the bladder. The procedure was repeated with correct injection of the tracer into the catheter. Wrong injection of the radiotracer into the catheter balloon should always be borne in mind in similar cases.

  13. Microfluidic preparation of radiopharmaceuticals for use in imaging studies

    NASA Astrophysics Data System (ADS)

    Collier, T. L.

    2014-05-01

    Microfluidics have revolutionized the field of radiopharmaceuticals in allowing for the rapid optimization of chemical processes and increased productivity in the preparation of radiotracers used in the development of imaging agents for clinical research and the study of biological processes. This presentation will cover the rapid preparation of radiotracers including simultaneous and sequential syntheses as well as the preparation of clinically useful amounts of radiotracers, as well as the rapid purification of such materials.

  14. (ACEEE summer study on energy efficiency in buildings)

    SciTech Connect

    Not Available

    1990-01-01

    The ACEEE Summer Study is a biennial conference that aims to bring together the foremost researchers, practitioners and policy makers involved in research on energy efficiency in buildings. The 1990 Summer Study had the objective to facilitate the exchange of research and implementation results and encourage the advancement of knowledge in the field of energy efficiency in buildings. The research papers presented at the conference published and distributed. Two hundred seventy two papers were presented. These individual papers, published in ten volumes, have been processed separately for the Energy Data Base.

  15. Clinical Translation of a Dual Integrin αvβ3- and Gastrin-Releasing Peptide Receptor-Targeting PET Radiotracer, 68Ga-BBN-RGD.

    PubMed

    Zhang, Jingjing; Niu, Gang; Lang, Lixin; Li, Fang; Fan, Xinrong; Yan, Xuefeng; Yao, Shaobo; Yan, Weigang; Huo, Li; Chen, Libo; Li, Zhiyuan; Zhu, Zhaohui; Chen, Xiaoyuan

    2017-02-01

    This study aimed to document the first-in-human application of a (68)Ga-labeled heterodimeric peptide BBN-RGD (bombesin-RGD) that targets both integrin αvβ3 and gastrin-releasing peptide receptor (GRPR). We evaluated the safety and assessed the clinical diagnostic value of (68)Ga-BBN-RGD PET/CT in prostate cancer patients in comparison with (68)Ga-BBN. Five healthy volunteers (4 men and 1 woman; age range, 28-53 y) were enrolled to validate the safety of (68)Ga-BBN-RGD. Dosimetry was calculated using the OLINDA/EXM software. Thirteen patients with prostate cancer (4 newly diagnosed and 9 posttherapy) were enrolled. All the patients underwent PET/CT scans 15-30 min after intravenous injection of 1.85 MBq (0.05 mCi) per kilogram of body weight of (68)Ga-BBN-RGD and also accepted (68)Ga-BBN PET/CT within 2 wk for comparison. With a mean injected dose of 107.3 ± 14.8 MBq per patient, no side effect was found during the whole procedure and 2 wk follow-up, demonstrating the safety of (68)Ga-BBN-RGD. A patient would be exposed to a radiation dose of 2.90 mSv with an injected dose of 129.5 MBq (3.5 mCi), which is much lower than the dose limit set by the Food and Drug Administration. In 13 patients with prostate cancer diagnosed by biopsy, (68)Ga-BBN-RGD PET/CT detected 3 of 4 primary tumors, 14 metastatic lymph nodes, and 20 bone lesions with an SUVmax of 4.46 ± 0.50, 6.26 ± 2.95, and 4.84 ± 1.57, respectively. Only 2 of 4 primary tumors, 5 lymph nodes, and 12 bone lesions were positive on (68)Ga-BBN PET/CT, with the SUVmax of 2.98 ± 1.24, 4.17 ± 1.89, and 3.61 ± 1.85, respectively. This study indicates the safety and efficiency of a new type of dual integrin αvβ3- and GRPR-targeting PET radiotracer in prostate cancer diagnosis and staging. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

  16. Optimizing tumor targeting of the lipophilic EGFR-binding radiotracer SKI 243 using a liposomal nanoparticle delivery system.

    PubMed

    Medina, Oula Penate; Pillarsetty, Nagavarakishore; Glekas, Athanasios; Punzalan, Blesida; Longo, Valerie; Gönen, Mithat; Zanzonico, Pat; Smith-Jones, Peter; Larson, Steven M

    2011-02-10

    Positron emission tomography (PET) of epidermal growth factor receptor (EGFR) kinase-specific radiolabeled tracers could provide a means for non-invasively characterizing EGFR expression and signaling activity in patients' tumors before, during, and after therapy with EGFR inhibitors. Towards this goal, our group has developed PET tracers which irreversibly bind to EGFR. However, tumor uptake is relatively low because of both the lipophilicity of such tracers (e.g. the morpholino-[124I]-IPQA [SKI 212243]), with octanol-to-water partition coefficients of up to 4, and a short dwell time in the blood and significant hepatobiliary clearance and intestinal reuptake. Liposomal nanoparticle delivery systems may favorably alter the pharmacokinetic profile and improve tumor targeting of highly lipophilic but otherwise promising cancer imaging tracers, such as the EGFR inhibitor SKI 243. SKI 243 is therefore an interesting model molecule for incorporation into lipid-based nanoparticles, as it would not only improve their solubility but also increase the circulation time, availability and, potentially, targeting of tumors. In the current study, we compared the pharmacokinetics and tumor targeting of the bare EGFR kinase-targeting radiotracer SKI 212243 (SKI 243) with that of the same tracer embedded in liposomes. SKI 243 and liposomal SKI 243 are both taken up by tumor xenografts but liposomal SKI 243 remained in the blood longer and consequently exhibited a 3- to 6-fold increase in uptake in the tumor among several other organs.

  17. Radiotracer computer modeling evidence that phospho-base methylation is the main route of choline synthesis in tobacco

    SciTech Connect

    McNeil, S.D.; Nuccio, M.L.; Rhodes, D.; Shachar-Hill, Y.; Hanson, A.D.

    2000-05-01

    Among flowering plants, the synthesis of choline (Cho) from ethanolamine (EA) can potentially occur via three parallel, interconnected pathways involving methylation of free bases, phospho-bases, or phosphatidyl-bases. The authors investigated which pathways operate in tobacco (Nicotiana tabacum L.) because previous work has shown that the endogenous Cho supply limits accumulation of glycine betaine in transgenic tobacco plants engineered to convert Cho to glycine betaine. The kinetics of metabolite labeling were monitored in leaf discs supplied with [{sup 33}P]phospho-EA,[{sup 33}P]phospho-monomethylethanolamine, or [{sup 14}C]formate, and the data were subjected to computer modeling. Because partial hydrolysis of phospho-bases occurred in the apoplast, modeling of phospho-base metabolism required consideration of the re-entry of [{sup 33}P]phosphate into the network. Modeling of [{sup 14}C]formate metabolism required consideration of the labeling of the EA and methyl moieties of Cho. Results supported the following conclusions: (a) The first methylation step occurs solely at the phospho-base level; (b) the second and third methylations occur mainly (83%--92% and 65%--85%, respectively) at the phospho-base level, with the remainder occurring at the phosphatidyl-base level; and (c) free Cho originates predominantly from phosphatidylcholine rather than from phospho-Cho. This study illustrates how computer modeling of radiotracer data, in conjunction with information on chemical pool sizes, can provide a coherent, quantitative picture of fluxes within a complex metabolic network.

  18. Results from an energy-efficient showerhead field study

    SciTech Connect

    Warwick, W.M.; Bailey, S.A.

    1993-06-01

    In 1991 the Bonneville Power Administration (Bonneville) initiated research to determine the energy savings potential of energy-efficient showerheads, including a two-phase study by Pacific Northwest Laboratory (PNL). The PNL study focused on 154 homes monitored with end-use metering equipment. In the first phase of the study, PNL recruited participants from the homes, installed energy efficient showerheads, and collected occupant and site characteristics data. The second phase of the study is an analysis of the end-use load data to estimate energy use and savings from showerheads over a two-year period. This report presents the results from the first phase field study. Program results are based on the number of homes that participated in various aspects of the study. Among the 154 of homes selected for the study, 65% agreed to participate. Eighty-eight percent of these homes actually had their showerheads replaced. After 15 months, 94% of the homes where showerheads were installed still had at least one in place. Measure results are based on the number of showerheads that were installed. The 154 homes contained an estimated 240 showerheads that could have been replaced. Sixty-six percent of these showerheads were actually replaced. If only showers in participant homes are considered, 83% of the showerheads were replaced. Measure persistence at the end of 15 months was 94%. The water flow rate from existing showerheads averaged 3.2 gallons per minute (gpm) at participating sites. Average water pressure for city-supplied water was 66 pounds per square inch (psi). Water pressure at homes on wells was over 40% lower, which reduced savings potential. The energy-efficient showerheads had an average flow rate of 1.8 gpm. Observed water flow reductions of 1.4 gpm were obtained from retrofit of energy-efficient showerheads. In about 20% of the showers, water flows remained constant or actually increased after retrofit of energy-efficient showerheads.

  19. Energy Efficiency of Higher Education Buildings: A Case Study

    ERIC Educational Resources Information Center

    Soares, Nelson; Pereira, Luísa Dias; Ferreira, João; Conceição, Pedro; da Silva, Patrícia Pereira

    2015-01-01

    Purpose: This paper aims to propose an energy efficiency plan (with technical and behavioural improvement measures) for a Portuguese higher education building--the Teaching Building of the Faculty of Economics of the University of Coimbra (FEUC). Design/methodology/approach: The study was developed in the context of both the "Green…

  20. Energy-Efficient Schools: Three Case Studies from Oregon.

    ERIC Educational Resources Information Center

    2003

    This document presents case studies of three schools or districts in Oregon that have implemented steps to promote energy efficiency. Steps taken by the schools include daylighting, energy audits, special energy loans, new ventilation design, and sustainable building practices. The facilities described are Ash Creek Intermediate School in…

  1. Energy Efficiency of Higher Education Buildings: A Case Study

    ERIC Educational Resources Information Center

    Soares, Nelson; Pereira, Luísa Dias; Ferreira, João; Conceição, Pedro; da Silva, Patrícia Pereira

    2015-01-01

    Purpose: This paper aims to propose an energy efficiency plan (with technical and behavioural improvement measures) for a Portuguese higher education building--the Teaching Building of the Faculty of Economics of the University of Coimbra (FEUC). Design/methodology/approach: The study was developed in the context of both the "Green…

  2. Radiosynthesis and Evaluation of [11C-Carbonyl]-Labeled Carbamates as Fatty Acid Amide Hydrolase Radiotracers for Positron Emission Tomography

    PubMed Central

    2012-01-01

    Fatty acid amide hydrolase (FAAH) plays a key role in regulating the tone of the endocannabinoid system. Radiotracers are required to image and quantify FAAH activity in vivo. We have synthesized a series of potent FAAH inhibitors encompassing two classes of N-alkyl-O-arylcarbamates and radiolabeled eight of them with carbon-11. The [11C-carbonyl]-radiotracers were evaluated in vitro and ex vivo in rats as potential FAAH imaging agents for positron emission tomography (PET). Both sets of [11C]O-arylcarbamates showed good to excellent brain penetration and an appropriate regional distribution. Pretreatments with a FAAH inhibitor demonstrated that 80–95% of brain uptake of radioactivity constituted binding of the radiotracers to FAAH. Brain extraction measurements showed that binding to FAAH was irreversible and kinetically different for the two classes of carbamates. These promising results are discussed in terms of the requirements of a suitable radiotracer for the in vivo imaging of FAAH using PET. PMID:23214511

  3. Operationally Efficient Propulsion System Study (OEPSS) data book. Executive summary

    NASA Technical Reports Server (NTRS)

    Wong, George S.

    1990-01-01

    The study was initiated to identify operations problems and cost drivers for current propulsion systems and to identify technology and design approaches to increase the operational efficiency and reduce operations costs for future propulsion systems. To provide readily usable data for the Advanced Launch System (ALS) program, the results of the Operationally Efficient Propulsion System Study (OEPSS) were organized into a series of OEPSS Data Books as follows: Volume 1, Generic Ground Operations Data; Volume 2, Ground Operations Problems; Volume 3, Operations Technology; Volume 4, OEPSS Design Concepts; and Volume 5, OEPSS Final Review Briefing, which summarizes the activities and results of the study. Summarized here are the salient results of the first year. A synopsis of each volume listed above is presented.

  4. Coupling Radiotracer Experiments with Chemical Fractionation for the Estimation of Respiratory Fluxes.

    PubMed

    Obata, Toshihiro; Rosado-Souza, Laise; Fernie, Alisdair R

    2017-01-01

    Carbohydrates catabolized via respiratory processes are not only used for energy production but also for biosynthesis of cellular components including soluble molecules (sugars, amino acids, organic acids, and their derivatives) and insoluble macromolecules (proteins, starch, and cell wall). Radiotracer experiments using (14)C-labeled glucose provide a global picture of the fate of respired carbon in the metabolic network. This method is based on a chemical fractionation of biomolecules in (14)C-glucose fed plant materials and the subsequent determination of radioactivity in each fraction. Metabolic flux into each fraction can be estimated from the specific activity of the hexose phosphate pool. Here, we describe the procedure for glucose metabolism in potato tuber but similar protocols can be adopted for various plant organs and substrates.

  5. Working against time: Rapid radiotracer synthesis and imaging the human brain

    SciTech Connect

    Fowler, J.S.; Wolf, A.P.

    1997-04-01

    In this Account, the authors describe some advances in radiotracer chemistry which have made it possible to probe the chemical anatomy of the human brain while working within a very restricted time scale. Though we highlight research from our laboratory, it is important to emphasize that advances in PET brain imaging have come from many laboratories throughout the world. Thus, for a more comprehensive treatment of PET technology the reader is referred to textbooks and review articles cited in this Account. Since many of the milestones in delineating biochemical transformations and the movement of drugs in the human brain have involved radiosynthesis with carbon-11 and fluorine-18, we focus on these two isotopes. 50 refs., 6 figs., 1 tab.

  6. Metabolite identification of a radiotracer by electrochemistry coupled to liquid chromatography with mass spectrometric and radioactivity detection.

    PubMed

    Baumann, Anne; Faust, Andreas; Law, Marylin P; Kuhlmann, Michael T; Kopka, Klaus; Schäfers, Michael; Karst, Uwe

    2011-07-01

    Radioligands, which specifically bind to a receptor or enzyme (target), enable molecular imaging of the target expression by positron emission tomography (PET). One very promising PET tracer is (S)-1-(4-(2-[(18)F]-fluoroethoxy)benzyl)-5-[1-(2-methoxymethylpyrrolidinyl)sulfonyl]isatin (isatin), a caspase-3 inhibitor, which has been developed at the University Hospital of Münster to image cell death (apoptosis). The translation of this novel tracer from preclinical evaluation to clinical examinations requires biodistribution studies, which characterize the pharmakodynamics and metabolic fate of the compound. This information is used to further optimize the radioligands and to interpret radioactive signals from tissues upon injection of the radioligand in vivo with respect to their specificity. The analysis of the metabolism of radioligands is hampered by the low amount of the compound being typically injected (nano/picomolar amount per injection). In the present study, electrochemistry (EC) is applied to elucidate the oxidative metabolism pathway of the radiotracer. Previous studies have demonstrated that EC can be utilized as a complementary tool to conventional in vitro approaches in drug metabolism studies. Thereby, potential oxidative metabolites of the isatin are determined by EC coupled to electrospray ionization mass spectrometry (EC/ESI-MS). Moreover, using EC/liquid chromatography (LC) and ESI-ion trap MS(n), structural elucidation of the oxidation products is performed. Comparatively to EC, in vitro metabolism studies with rat liver microsomes are conducted. Finally, the developed LC/ESI-MS method is applied to determine metabolites in body fluids and cell extracts from in vivo studies with the nonradioactive ((19)F) and radioactive isatin ((18)F). On the basis of the electrochemically generated oxidation products of the radioligand, the major radioactive metabolite occurring in vivo was successfully identified.

  7. A study of IMRT planning parameters on planning efficiency, delivery efficiency, and plan quality

    SciTech Connect

    Mittauer, Kathryn; Lu Bo; Yan Guanghua; Kahler, Darren; Amdur, Robert; Liu Chihray; Gopal, Arun

    2013-06-15

    Purpose: To improve planning and delivery efficiency of head and neck IMRT without compromising planning quality through the evaluation of inverse planning parameters.Methods: Eleven head and neck patients with pre-existing IMRT treatment plans were selected for this retrospective study. The Pinnacle treatment planning system (TPS) was used to compute new treatment plans for each patient by varying the individual or the combined parameters of dose/fluence grid resolution, minimum MU per segment, and minimum segment area. Forty-five plans per patient were generated with the following variations: 4 dose/fluence grid resolution plans, 12 minimum segment area plans, 9 minimum MU plans, and 20 combined minimum segment area/minimum MU plans. Each plan was evaluated and compared to others based on dose volume histograms (DVHs) (i.e., plan quality), planning time, and delivery time. To evaluate delivery efficiency, a model was developed that estimated the delivery time of a treatment plan, and validated through measurements on an Elekta Synergy linear accelerator. Results: The uncertainty (i.e., variation) of the dose-volume index due to dose calculation grid variation was as high as 8.2% (5.5 Gy in absolute dose) for planning target volumes (PTVs) and 13.3% (2.1 Gy in absolute dose) for planning at risk volumes (PRVs). Comparison results of dose distributions indicated that smaller volumes were more susceptible to uncertainties. The grid resolution of a 4 mm dose grid with a 2 mm fluence grid was recommended, since it can reduce the final dose calculation time by 63% compared to the accepted standard (2 mm dose grid with a 2 mm fluence grid resolution) while maintaining a similar level of dose-volume index variation. Threshold values that maintained adequate plan quality (DVH results of the PTVs and PRVs remained satisfied for their dose objectives) were 5 cm{sup 2} for minimum segment area and 5 MU for minimum MU. As the minimum MU parameter was increased, the number of

  8. A study of IMRT planning parameters on planning efficiency, delivery efficiency, and plan quality.

    PubMed

    Mittauer, Kathryn; Lu, Bo; Yan, Guanghua; Kahler, Darren; Gopal, Arun; Amdur, Robert; Liu, Chihray

    2013-06-01

    To improve planning and delivery efficiency of head and neck IMRT without compromising planning quality through the evaluation of inverse planning parameters. Eleven head and neck patients with pre-existing IMRT treatment plans were selected for this retrospective study. The Pinnacle treatment planning system (TPS) was used to compute new treatment plans for each patient by varying the individual or the combined parameters of dose∕fluence grid resolution, minimum MU per segment, and minimum segment area. Forty-five plans per patient were generated with the following variations: 4 dose∕fluence grid resolution plans, 12 minimum segment area plans, 9 minimum MU plans, and 20 combined minimum segment area∕minimum MU plans. Each plan was evaluated and compared to others based on dose volume histograms (DVHs) (i.e., plan quality), planning time, and delivery time. To evaluate delivery efficiency, a model was developed that estimated the delivery time of a treatment plan, and validated through measurements on an Elekta Synergy linear accelerator. The uncertainty (i.e., variation) of the dose-volume index due to dose calculation grid variation was as high as 8.2% (5.5 Gy in absolute dose) for planning target volumes (PTVs) and 13.3% (2.1 Gy in absolute dose) for planning at risk volumes (PRVs). Comparison results of dose distributions indicated that smaller volumes were more susceptible to uncertainties. The grid resolution of a 4 mm dose grid with a 2 mm fluence grid was recommended, since it can reduce the final dose calculation time by 63% compared to the accepted standard (2 mm dose grid with a 2 mm fluence grid resolution) while maintaining a similar level of dose-volume index variation. Threshold values that maintained adequate plan quality (DVH results of the PTVs and PRVs remained satisfied for their dose objectives) were 5 cm(2) for minimum segment area and 5 MU for minimum MU. As the minimum MU parameter was increased, the number of segments and delivery

  9. PET Cell Tracking Using 18F-FLT is Not Limited by Local Reuptake of Free Radiotracer

    PubMed Central

    MacAskill, Mark G.; Tavares, Adriana S.; Wu, Junxi; Lucatelli, Christophe; Mountford, Joanne C.; Baker, Andrew H.; Newby, David E.; Hadoke, Patrick W. F.

    2017-01-01

    Assessing the retention of cell therapies following implantation is vital and often achieved by labelling cells with 2′-[18F]-fluoro-2′-deoxy-D-glucose (18F-FDG). However, this approach is limited by local retention of cell-effluxed radiotracer. Here, in a preclinical model of critical limb ischemia, we assessed a novel method of cell tracking using 3′-deoxy-3′-L-[18F]-fluorothymidine (18F-FLT); a clinically available radiotracer which we hypothesise will result in minimal local radiotracer reuptake and allow a more accurate estimation of cell retention. Human endothelial cells (HUVECs) were incubated with 18F-FDG or 18F-FLT and cell characteristics were evaluated. Dynamic positron emission tomography (PET) images were acquired post-injection of free 18F-FDG/18F-FLT or 18F-FDG/18F-FLT-labelled HUVECs, following the surgical induction of mouse hind-limb ischemia. In vitro, radiotracer incorporation and efflux was similar with no effect on cell viability, function or proliferation under optimised conditions (5 MBq/mL, 60 min). Injection of free radiotracer demonstrated a faster clearance of 18F-FLT from the injection site vs. 18F-FDG (p ≤ 0.001), indicating local cellular uptake. Using 18F-FLT-labelling, estimation of HUVEC retention within the engraftment site 4 hr post-administration was 24.5 ± 3.2%. PET cell tracking using 18F-FLT labelling is an improved approach vs. 18F-FDG as it is not susceptible to local host cell reuptake, resulting in a more accurate estimation of cell retention. PMID:28287126

  10. Predicting Future Morphological Changes of Lesions from Radiotracer Uptake in 18F-FDG-PET Images

    PubMed Central

    Bagci, Ulas; Yao, Jianhua; Miller-Jaster, Kirsten; Chen, Xinjian; Mollura, Daniel J.

    2013-01-01

    We introduce a novel computational framework to enable automated identification of texture and shape features of lesions on 18F-FDG-PET images through a graph-based image segmentation method. The proposed framework predicts future morphological changes of lesions with high accuracy. The presented methodology has several benefits over conventional qualitative and semi-quantitative methods, due to its fully quantitative nature and high accuracy in each step of (i) detection, (ii) segmentation, and (iii) feature extraction. To evaluate our proposed computational framework, thirty patients received 2 18F-FDG-PET scans (60 scans total), at two different time points. Metastatic papillary renal cell carcinoma, cerebellar hemongioblastoma, non-small cell lung cancer, neurofibroma, lymphomatoid granulomatosis, lung neoplasm, neuroendocrine tumor, soft tissue thoracic mass, nonnecrotizing granulomatous inflammation, renal cell carcinoma with papillary and cystic features, diffuse large B-cell lymphoma, metastatic alveolar soft part sarcoma, and small cell lung cancer were included in this analysis. The radiotracer accumulation in patients' scans was automatically detected and segmented by the proposed segmentation algorithm. Delineated regions were used to extract shape and textural features, with the proposed adaptive feature extraction framework, as well as standardized uptake values (SUV) of uptake regions, to conduct a broad quantitative analysis. Evaluation of segmentation results indicates that our proposed segmentation algorithm has a mean dice similarity coefficient of 85.75±1.75%. We found that 28 of 68 extracted imaging features were correlated well with SUVmax (p<0.05), and some of the textural features (such as entropy and maximum probability) were superior in predicting morphological changes of radiotracer uptake regions longitudinally, compared to single intensity feature such as SUVmax. We also found that integrating textural features with SUV measurements

  11. A study of efficiency in low resistivity silicon solar cells

    NASA Technical Reports Server (NTRS)

    Dunbar, P. M.; Hauser, J. R.

    1976-01-01

    A general device-analysis program has been utilized to study the efficiency of silicon solar cells. The analysis is applied to specific geometries of both n(+)-p and n(+)-p-p(+) solar cells, and involves a numerical solution of the basic transport and continuity equations. This approach allows solutions that are free of typical limiting assumptions involved in solving the device equations as well as solutions relating to lifetime, mobility variations, and diffused-region profiles. The analysis includes available empirical information on diffusion length, mobility, and lifetime as a function of doping, as well as a Gaussian profile for the diffused region. Results are presented which illustrate the limitations of efficiency as a function of doping. It is found that the maximum efficiencies for both types of cell converge at lower resistivities to around 16% with air-mass-zero radiation and a single-layer absorbing-SiO antireflecting film. It is also found that the minority-carrier lifetime, both in the n(+) surface and p-type bulk regions, presents serious limitations to conversion efficiency, particularly in the low-resistivity cells.

  12. A study of efficiency in low resistivity silicon solar cells

    NASA Technical Reports Server (NTRS)

    Dunbar, P. M.; Hauser, J. R.

    1976-01-01

    A general device-analysis program has been utilized to study the efficiency of silicon solar cells. The analysis is applied to specific geometries of both n(+)-p and n(+)-p-p(+) solar cells, and involves a numerical solution of the basic transport and continuity equations. This approach allows solutions that are free of typical limiting assumptions involved in solving the device equations as well as solutions relating to lifetime, mobility variations, and diffused-region profiles. The analysis includes available empirical information on diffusion length, mobility, and lifetime as a function of doping, as well as a Gaussian profile for the diffused region. Results are presented which illustrate the limitations of efficiency as a function of doping. It is found that the maximum efficiencies for both types of cell converge at lower resistivities to around 16% with air-mass-zero radiation and a single-layer absorbing-SiO antireflecting film. It is also found that the minority-carrier lifetime, both in the n(+) surface and p-type bulk regions, presents serious limitations to conversion efficiency, particularly in the low-resistivity cells.

  13. H-CRRETAWAC-OH, a Lead Structure for the Development of Radiotracer Targeting Integrin α5β1?

    PubMed Central

    Maschauer, Simone; Einsiedel, Jürgen; Eder, Iris E.; Gmeiner, Peter; Virgolini, Irene J.

    2014-01-01

    Imaging of angiogenic processes is of great interest in preclinical research as well as in clinical settings. The most commonly addressed target structure for imaging angiogenesis is the integrin αvβ3. Here we describe the synthesis and evaluation of [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH, a radiolabelled peptide designed to selectively target the integrin α5β1. Conjugation of 4-nitrophenyl-(RS)-2-[18F]fluoropropionate provided [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH in high radiochemical purity (>95%) and a radiochemical yield of approx. 55%. In vitro evaluation showed α5β1 binding affinity in the nanomolar range, whereas affinity to αvβ3 and αIIbβ3 was >50 μM. Cell uptake studies using human melanoma M21 (αvβ3-positive andα5β1-negative), human melanoma M21-L (αvβ3-negative and α5β1-negative), and human prostate carcinoma DU145 (αvβ3-negative and α5β1-positive) confirmed receptor-specific binding. The radiotracer was stable in human serum and showed low protein binding. Biodistribution studies showed tumour uptake ranging from 2.5 to 3.5% ID/g between 30 and 120 min post-injection. However, blocking studies and studies using mice bearing α5β1-negative M21 tumours did not confirm receptor-specific uptake of [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH, although this radiopeptide revealed high affinity and substantial selectivity to α5β1 in vitro. Further experiments are needed to study the in vivo metabolism of this peptide and to develop improved radiopeptide candidates suitable for PET imaging of α5β1 expression in vivo. PMID:25374888

  14. Operationally Efficient Propulsion System Study (OEPSS): OEPSS Video Script

    NASA Technical Reports Server (NTRS)

    Wong, George S.; Waldrop, Glen S.; Trent, Donnie (Editor)

    1992-01-01

    The OEPSS video film, along with the OEPSS Databooks, provides a data base of current launch experience that will be useful for design of future expendable and reusable launch systems. The focus is on the launch processing of propulsion systems. A brief 15-minute overview of the OEPSS study results is found at the beginning of the film. The remainder of the film discusses in more detail: current ground operations at the Kennedy Space Center; typical operations issues and problems; critical operations technologies; and efficiency of booster and space propulsion systems. The impact of system architecture on the launch site and its facility infrastucture is emphasized. Finally, a particularly valuable analytical tool, developed during the OEPSS study, that will provide for the "first time" a quantitative measure of operations efficiency for a propulsion system is described.

  15. [Efficiency of standard versus instrumental studies in detecting helminth eggs].

    PubMed

    Upyrev, A V; Khromenkova, E P; Tverdokhlebova, T I

    2012-01-01

    Testing confirmed that the applied brush washing methods developed in the 1970s could provide the adequate representativeness of a sample and full information on the actual presence of helminth eggs in the objects under study. An instrumental study was found to increase the probability of helminth egg detection by up to 3.1 times due to the representativeness of a sample, to reduce the labor- and time-consumption to have analysis results, as well as to unify a procedure for sanitary parasitological studies of washouts, and to enhance the efficiency of the equipment already used in parasitology laboratories.

  16. Development of Kit Formulations for 99mTcN-MPO: A Cationic Radiotracer for Myocardial Perfusion Imaging

    PubMed Central

    Zheng, Yumin; Ji, Shundong; Tomaselli, Elena; Liu, Shuang

    2015-01-01

    The objective of this study was to develop a kit formulation for 99mTcN-MPO to support its clinical evaluations as a SPECT radiotracer. Radiolabeling studies were performed using three different formulations (two-vial formulation and single-vial formulations with/without SnCl2) to explore the factors influencing radiochemical purity (RCP) of 99mTcN-MPO. We found that the most important factor affecting the RCP of 99mTcN-MPO was the purity of PNP5. 99mTcN-MPO was prepared >98% RCP (n = 20) using the two-vial formulation. For single-vial formulations with/without SnCl2, β-cyclodextrin (β-CD) is particularly useful as a stabilizer for PNP5. The RCP of 99mTcN-MPO was 95 – 98% using β-CD, but its RCP was only 90 – 93% with γ-CD. It seems that PNP5 fits better into the inner cavity of β-CD, which forms more stable inclusion complex than γ-CD in the single-vial formulations. The results from biodistribution and imaging studies in Sprague-Dawley (SD) rats clearly demonstrated biological equivalence of three different formulations. SPECT data suggested that high quality images could be obtained at 0 – 30 min post-injection without significant interference from the liver radioactivity. Considering the ease for 99mTc-labeling and high RCP of 99mTcN-MPO, the non-SnCl2 single-vial formulation is an attractive choice for future clinical studies. PMID:25070025

  17. Human Brain Imaging of α7 nAChR with [18F]ASEM: a New PET Radiotracer for Neuropsychiatry and Determination of Drug Occupancy

    PubMed Central

    Wong, Dean F.; Kuwabara, Hiroto; Pomper, Martin; Holt, Daniel P.; Brasic, James R.; George, Noble; Frolov, Boris; Willis, William; Gao, Yongjun; Valentine, Heather; Nandi, Ayon; Gapasin, Lorena; Dannals, Robert F.; Horti, Andrew G.

    2017-01-01

    Purpose Using the α7-nAChR radiotracer, [18F]ASEM, we present the first successful human positron emission tomography (PET) studies. Rodent occupancy with three clinically employed α7-nAChR drugs confirms the specificity of the radiotracer. Procedures Five healthy male subjects were imaged for 90 min following IV [18F]ASEM. Two subjects were scanned for the second time (test/retest; TRV). Mouse biodistribution of [18F]ASEM was carried out in CD1 mice injected with using human equivalent doses of DMXB-A, EVP-6124, and varenicline to block specific binding. Results [18F]ASEM readily entered the brain and peaked at 15 min post-injection with reversible kinetics and a peak %SUV of about 400 %. The regional human brain distribution of [18F]ASEM matched previous in vitro data and baboon PET results. The precuneus, parietal, occipital, cingulate cortexes, putamen, and thalamus showed high values of distribution volume (>20 ml/ml) and binding potentials >1 with TRV averaged 10.8±5.1 %. In mouse distribution studies, there was significant dose-dependent blockade in the mouse brain with DMXB-A as well as the other two α7-nAChR drugs. Conclusions The characteristics of [18F]ASEM are consistent with the ability to quantify α7-nAChR in the human brain. [18F]ASEM is suitable for imaging neuropsychiatric disorders and target engagement (receptor occupancy) of potential α7-nAChR drugs. PMID:25145965

  18. Aircraft energy efficiency laminar flow control wing design study

    NASA Technical Reports Server (NTRS)

    Bonner, T. F., Jr.; Pride, J. D., Jr.; Fernald, W. W.

    1977-01-01

    An engineering design study was performed in which laminar flow control (LFC) was integrated into the wing of a commercial passenger transport aircraft. A baseline aircraft configuration was selected and the wing geometry was defined. The LFC system, with suction slots, ducting, and suction pumps was integrated with the wing structure. The use of standard aluminum technology and advanced superplastic formed diffusion bonded titanium technology was evaluated. The results of the design study show that the LFC system can be integrated with the wing structure to provide a structurally and aerodynamically efficient wing for a commercial transport aircraft.

  19. 2'[(18)F]-fluoroethylrhodamine B is a promising radiotracer to measure P-glycoprotein function.

    PubMed

    Trencsényi, György; Kertész, István; Krasznai, Zoárd T; Máté, Gábor; Szalóki, Gábor; Szabó Judit, P; Kárpáti, Levente; Krasznai, Zoltán; Márián, Teréz; Goda, Katalin

    2015-07-10

    In vivo detection of the emergence of P-glycoprotein (Pgp) mediated multidrug resistance in tumors could be beneficial for patients treated with anticancer drugs. PET technique in combination with appropriate radiotracers could be the most convenient method for detection of Pgp function. Rhodamine derivatives are validated fluorescent probes for measurement of mitochondrial membrane potential and also Pgp function. The aim of this study was to investigate whether 2'[(18)F]-fluoroethylrhodamine B ((18)FRB) a halogenated rhodamine derivative previously synthesized for PET assessment of myocardial perfusion preserved its Pgp substrate character. ATPase assay as well as accumulation experiments carried out using Pgp(+) and Pgp(-) human gynecologic (A2780/A2780(AD) and KB-3-1/KB-V1) and a mouse fibroblast cell pairs (NIH 3T3 and NIH 3T3 MDR1) were applied to study the interaction of (18)FRB with Pgp. ATPase assay proved that (18)FRB is a high affinity substrate of Pgp. Pgp(-) cells accumulated the (18)FRB rapidly in accordance with its lipophilic character. Dissipation of the mitochondrial proton gradient by a proton ionophore CCCP decreased the accumulation of rhodamine 123 (R123) and (18)FRB into Pgp(-) cells. Pgp(+) cells exhibited very low R123 and (18)FRB accumulation (around 1-8% of the Pgp(-) cell lines) which was not sensitive to the mitochondrial proton gradient; rather it was increased by the Pgp inhibitor cyclosporine A (CsA). Based on the above data we conclude that (18)FRB is a high affinity Pgp substrate and consequently a potential PET tracer to detect multidrug resistant tumors as well as the function of physiological barriers expressing Pgp.

  20. Cutting Efficiency of Instruments with Different Movements: a Comparative Study

    PubMed Central

    Plotino, Gianluca; Al-Sudani, Dina; Rubini, Alessio Giansiracusa; Sannino, Gianpaolo; Piasecki, Lucila; Putortì, Ermanno; Testarelli, Luca; Gambarini, Gianluca

    2015-01-01

    ABSTRACT Objectives The aim of the present study was to evaluate the cutting efficiency of two new reciprocating instruments, Twisted File Adaptive and WaveOne Primary. Material and Methods 10 new Twisted File Adaptive (TF Adaptive) (SybronEndo, Glendora, CA, USA) and 10 new WaveOne Primary files (Dentsply Maillefer, Ballaigues, Switzerland) were activated using a torque-controlled motor, respectively TFA motor (SybronEndo, Glendora, CA, USA) and Silver motor (VDW, Munich, Germany). The device used for the cutting test consisted on a mainframe to which a mobile plastic support for the hand-piece is connected and a stainless-steel block containing a Plexiglas block against which the cutting efficiency of the instruments was tested. The length of the block cut in 1 minute was measured in a computerized program with a precision of 0.1 mm. Mean and standard deviations of each group were calculated and data were statistically analyzed with one-way ANOVA and Bonferroni t test (P < 0.05). Results TF Adaptive displayed significantly greater maximum penetration depth than WaveOne Primary (P < 0.05). In fact, TF Adaptive instruments (Group 1) cut the Plexiglas block to a mean depth of 8.7 (SD 0.5) mm, while WaveOne Primary instruments cut the Plexiglas block to a mean depth of 6.4 (SD 0.3) mm. Conclusions Twisted File Adaptive instruments demonstrated statistically higher cutting efficiency than WaveOne instruments. PMID:25937877

  1. Cutting efficiency of instruments with different movements: a comparative study.

    PubMed

    Tocci, Luigi; Plotino, Gianluca; Al-Sudani, Dina; Rubini, Alessio Giansiracusa; Sannino, Gianpaolo; Piasecki, Lucila; Putortì, Ermanno; Testarelli, Luca; Gambarini, Gianluca

    2015-01-01

    The aim of the present study was to evaluate the cutting efficiency of two new reciprocating instruments, Twisted File Adaptive and WaveOne Primary. 10 new Twisted File Adaptive (TF Adaptive) (SybronEndo, Glendora, CA, USA) and 10 new WaveOne Primary files (Dentsply Maillefer, Ballaigues, Switzerland) were activated using a torque-controlled motor, respectively TFA motor (SybronEndo, Glendora, CA, USA) and Silver motor (VDW, Munich, Germany). The device used for the cutting test consisted on a mainframe to which a mobile plastic support for the hand-piece is connected and a stainless-steel block containing a Plexiglas block against which the cutting efficiency of the instruments was tested. The length of the block cut in 1 minute was measured in a computerized program with a precision of 0.1 mm. Mean and standard deviations of each group were calculated and data were statistically analyzed with one-way ANOVA and Bonferroni t test (P < 0.05). TF Adaptive displayed significantly greater maximum penetration depth than WaveOne Primary (P < 0.05). In fact, TF Adaptive instruments (Group 1) cut the Plexiglas block to a mean depth of 8.7 (SD 0.5) mm, while WaveOne Primary instruments cut the Plexiglas block to a mean depth of 6.4 (SD 0.3) mm. Twisted File Adaptive instruments demonstrated statistically higher cutting efficiency than WaveOne instruments.

  2. Swimming Efficiently: An Analytical Study of Optimal Swimming in Fish

    NASA Astrophysics Data System (ADS)

    Wiens, A. Josh; Hosoi, Anette

    2014-11-01

    The Strouhal Number (St) , is widely considered to be the defining parameter for efficient undulatory swimming. Biological studies have shown that fish species across a broad range of shapes and sizes adhere to a narrow St range (0 . 2 < St < 0 . 4). Despite its significance, St alone provides an incomplete description of the kinematics and geometry of a swimming fish. The dimensionless speed and amplitude of the body wave, along with the size and shape of the body can also play a significant role in swimming performance. We apply Lighthill's elongated body theory to construct a simple but powerful reduction of the steady-swimming problem. Through this reduction, the energetic efficiency of a swimming fish can be directly expressed as an analytical function of body geometry and kinematics. In this reduced form, the interplay between the parameters of the system, and their collective role in determining the performance of the swimmer can be readily observed and understood. In particular, the reduced model is applied to understand how wave amplitude, wave speed, and St must relate for optimal swimming efficiency. Following this, we then explore how these relationships are altered by geometric factors such as tail size and compliance.

  3. Pre-clinical validation of a novel alpha-7 nicotinic receptor radiotracer, [(3)H]AZ11637326: target localization, biodistribution and ligand occupancy in the rat brain.

    PubMed

    Maier, Donna L; Hill, Geraldine; Ding, Min; Tuke, David; Einstein, Emily; Gurley, David; Gordon, John C; Bock, Mary J; Smith, Jeff S; Bialecki, Russell; Eisman, Mark; Elmore, Charles S; Werkheiser, Jennifer L

    2011-01-01

    The alpha-7 neuronal nicotinic receptor is a novel pharmacological target for psychiatric and cognitive disorders. Selective radiotracer tools for pre-clinical receptor occupancy can facilitate the interpretation of the biological actions of small molecules at a target receptor. We discovered a high affinity nicotinic alpha-7 subtype-selective ligand, AZ11637326, with physical-chemical and pharmacokinetic properties suitable for an in vivo radioligand tool. [(3)H]AZ11637326 synthesis by tritiodehalogenation of the corresponding tribromide precursor yielded a high specific activity radiotracer with high affinity alpha-7 receptor binding in the rat hippocampus determined by autoradiography (Kd = 0.2 nM). When [(3)H]AZ11637326 was administered to rats by intravenous bolus, rapid uptake was measured in the brain followed by a 3-4 fold greater specific binding in regions containing the alpha-7 receptor (frontal cortex, hippocampus, hypothalamus and midbrain) when compared to non-target regions (striatum and cerebellum). Systemic administration of the high affinity alpha-7 receptor antagonist, methyllycaconitine (MLA), or pretreatment with alpha-7 selective agonists (AR-R17779, PyrQTC, DBCO-4-POM, and DBCO-3-POM) significantly blocked the alpha-7 specific binding of [(3)H]AZ11637326 in the rat brain. The rank order of ligand ED(50) values for in vivo alpha-7 receptor occupancy in rat hippocampus was: DBCO-4-POM > DBCO-3-POM ∼ MLA > PyrQTC > AR-R17779. The occupancy affinity shift was consistent with in vitro binding affinity in autoradiography. Our studies established the optimal conditions for [(3)H]AZ11637326 in vivo specific binding in the rat brain and support the use of [(3)H]AZ11637326 as a pre-clinical tool for assessment of novel alpha-7 compounds in drug discovery.

  4. (Findings of the Costa Rica power sector efficiency study)

    SciTech Connect

    Waddle, D.B.

    1990-10-08

    To present findings of the Costa Rica Power Sector Efficiency Study to the Instituto Costarricense de Electridad, and to the Ministry of Energy, Natural Resources and Mining. To discuss the progress and plans for the Central American Rural Electrification Project with US Agency for International Development (USAID)/Regional Office Central American Program (ROCAP). I traveled to San Jose, Costa Rica to present the findings of the Costa Rica Power Sector Efficiency Study to our counterparts in the utility and the Ministry of Energy. Discussions were held with line level managers at Instituto Costarricensede Electricidad (ICE) and Ministry of Energy Mines and Natural Resources (MIRENEM), as well as a plan of action set for the final stage of the project. Discussions were held for a one day period with both the bilateral Agency for International Development (AID) and the regional AID mission regarding the need for a similar study in Guatemala and matters directly pertaining to the Central American Rural Electrification Study (CARES) project.

  5. Studying synaptic efficiency by post-hoc immunolabelling

    PubMed Central

    2013-01-01

    Background In terms of vesicular recycling, synaptic efficiency is a key determinant of the fidelity of synaptic transmission. The ability of a presynaptic terminal to reuse its vesicular content is thought to be a signature of synaptic maturity and this process depends on the activity of several proteins that govern exo/endocytosis. Upon stimulation, individual terminals in networks of cultured cerebellar granule neurons exhibit heterogeneous exocytic responses, which reflect the distinct states of maturity and plasticity intrinsic to individual synaptic terminals. This dynamic scenario serves as the substrate for processes such as scaling, plasticity and synaptic weight redistribution. Presynaptic strength has been associated with the activity of several types of proteins, including the scaffolding proteins that form the active zone cytomatrix and the proteins involved in presynaptic exocytosis. Methods We have combined fluorescence imaging techniques using the styryl dye FM1-43 in primary cultures of cerebellar granule cells with subsequent post-hoc immunocytochemistry in order to study synaptic efficiency in terms of vesicular release. We describe a protocol to easily quantify these results with minimal user intervention. Results In this study we describe a technique that specifically correlates presynaptic activity with the levels of presynaptic markers. This method involves the use of the styryl dye FM1-43 to estimate the release capacity of a synaptic terminal, and the subsequent post-hoc immunolabelling of thousands of individual nerve terminals. We observed a strong correlation between the release capacity of the nerve terminal and the levels of the RIM1α but not the Munc13-1 protein in the active zone. Conclusions Our findings support those of previous studies and point out to RIM1α as a crucial factor in determining synaptic efficiency. These results also demonstrate that this technique is a useful tool to analyse the molecular differences

  6. Efficiency Studies for the new Muon Telescope Detector at STAR

    NASA Astrophysics Data System (ADS)

    Carson, Hannah; STAR Collaboration

    2013-10-01

    The Muon Telescope Detector (MTD) is a new detector subsystem in STAR at the Relativistic Heavy Ion Collider (RHIC). The MTD will contribute to studies of the matter being created in heavy-ion collisions by allowing measurements of the J/Psi meson and the different Upsilon states over a broad transverse momentum range via the reconstruction of their di-muon decays. Simulations to estimate the efficiency of the MTD for detecting muons were performed. The results of these simulations will be presented.

  7. Energy efficient engine: Preliminary design and integration studies

    NASA Technical Reports Server (NTRS)

    Johnston, R. P.; Hirschkron, R.; Koch, C. C.; Neitzel, R. E.; Vinson, P. W.

    1978-01-01

    Parametric design and mission evaluations of advanced turbofan configurations were conducted for future transport aircraft application. Economics, environmental suitability and fuel efficiency were investigated and compared with goals set by NASA. Of the candidate engines which included mixed- and separate-flow, direct-drive and geared configurations, an advanced mixed-flow direct-drive configuration was selected for further design and evaluation. All goals were judged to have been met except the acoustic goal. Also conducted was a performance risk analysis and a preliminary aerodynamic design of the 10 stage 23:1 pressure ratio compressor used in the study engines.

  8. Radiation efficiency during slow crack propagation: an experimental study.

    NASA Astrophysics Data System (ADS)

    Jestin, Camille; Lengliné, Olivier; Schmittbuhl, Jean

    2017-04-01

    Creeping faults are known to host a significant aseismic deformation. However, the observations of micro-earthquake activity related to creeping faults (e.g. San Andreas Faults, North Anatolian Fault) suggest the presence of strong lateral variabilities of the energy partitioning between radiated and fracture energies. The seismic over aseismic slip ratio is rather difficult to image over time and at depth because of observational limitations (spatial resolution, sufficiently broad band instruments, etc.). In this study, we aim to capture in great details the energy partitioning during the slow propagation of mode I fracture along a heterogeneous interface, where the toughness is strongly varying in space.We lead experiments at laboratory scale on a rock analog model (PMMA) enabling a precise monitoring of fracture pinning and depinning on local asperities in the brittle-creep regime. Indeed, optical imaging through the transparent material allows the high resolution description of the fracture front position and velocity during its propagation. At the same time, acoustic emissions are also measured by accelerometers positioned around the rupture. Combining acoustic records, measurements of the crack front position and the loading curve, we compute the total radiated energy and the fracture energy. We deduce from them the radiation efficiency, ηR, characterizing the proportion of the available energy that is radiated in form of seismic wave. We show an increase of ηR with the crack rupture speed computed for each of our experiments in the sub-critical crack propagation domain. Our experimental estimates of ηR are larger than the theoretical model proposed by Freund, stating that the radiation efficiency of crack propagation in homogeneous media is proportional to the crack velocity. Our results are demonstrated to be in agreement with existing studies which showed that the distribution of crack front velocity in a heterogeneous medium can be well described by a

  9. Development of gamma emitting receptor binding radiotracers for imaging the brain and pancreas. Final technical progress report, March 1, 1988--May 31, 1993

    SciTech Connect

    1996-01-01

    This document give paragraph synopses of results in research on brain and pancreas imaging, using radiotracers. General catagories of research included chemistry, pharmacology, imaging physics, and kinetic modeling. A list of publications is included

  10. Semi-automated lab-on-a-chip for dispensing GA-68 radiotracers

    SciTech Connect

    Weinberg, Irving

    2014-03-12

    We solved a technical problem that is hindering American progress in molecular medicine, and restricting US citizens from receiving optimal diagnostic care. Specifically, the project deals with a mother/daughter generator of positron-emitting radiotracers (Ge-68/Ga-68). These generator systems are approved in Europe but cannot be used in the USA, because of safety issues related to possible breakthrough of long-lived Ge-68 (mother) atoms. Europeans have demonstrated abilities of Ga-68-labeled radiotracers to image cancer foci with high sensitivity and specificity, and to use such methods to effectively plan therapy.The USA Food and Drug Administration (FDA) and Nuclear Regulatory Commission (NRC) have taken the position that every patient administration of Ga-68 should be preceded by an assay demonstrated that Ge-68 breakthrough is within acceptable limits. Breakthrough of parent elements is a sensitive subject at the FDA, as evidenced by the recent recall of Rb-82 generators due to inadvertent administrations of Sr-82. Commercially, there is no acceptable rapid method for assaying breakthrough of Ge-68 prior to each human administration. The gamma emissions of daughter Ga-68 have higher energies than the parent Ge-68, so that the shielding assays typically employed for Mo-99/Tc-99m generators cannot be applied to Ga-68 generators. The half-life of Ga-68 is 68 minutes, so that the standard 10-half-life delay (used to assess breakthrough in Sr-82/Rb-82 generators) cannot be applied to Ga-68 generators. As a result of the aforementioned regulatory requirements, Ga-68 generators are sold in the USA for animal use only.The American clinical community’s inability to utilize Ga-68 generators impairs abilities to treat patients domestically, and puts the USA at a disadvantage in developing exportable products. The proposed DOE project aimed to take advantage of recent technological advances developed for lab-on-a-chip (LOC) applications. Based on our experiences

  11. Energy efficient engine preliminary design and integration study

    NASA Technical Reports Server (NTRS)

    Gray, D. E.

    1978-01-01

    The technology and configurational requirements of an all new 1990's energy efficient turbofan engine having a twin spool arrangement with a directly coupled fan and low-pressure turbine, a mixed exhaust nacelle, and a high 38.6:1 overall pressure ratio were studied. Major advanced technology design features required to provide the overall benefits were a high pressure ratio compression system, a thermally actuated advanced clearance control system, lightweight shroudless fan blades, a low maintenance cost one-stage high pressure turbine, a short efficient mixer and structurally integrated engine and nacelle. A conceptual design analysis was followed by integration and performance analyses of geared and direct-drive fan engines with separate or mixed exhaust nacelles to refine previously designed engine cycles. Preliminary design and more detailed engine-aircraft integration analysis were then conducted on the more promising configurations. Engine and aircraft sizing, fuel burned, and airframe noise studies on projected 1990's domestic and international aircraft produced sufficient definition of configurational and advanced technology requirements to allow immediate initiation of component technology development.

  12. Bilateral axillary lymph node uptake of radiotracer during lower extremity and scrotal lymphoscintigraphy in a case of primary scrotal lymphoedema

    PubMed Central

    Jain, Anuj; Jaimini, Abhinav

    2011-01-01

    Lymphoscintigraphy is a useful technique for the evaluation of lymphatic function in the presence of limb swelling. The authors report a case where genital swelling in a 20-year-old man was investigated by lymphoscintigraphy. We performed lower limb lymphoscintigraphy and scrotal lymphoscintigraphy in the patient on two different days. Lower limb revealed dermal backflow pattern in lower limbs, inguinoscrotal reflux of the lymph and unexpected avid radiotracer uptake in the axillae bilaterally. Scrotal lymphoscintigraphy revealed slow movement of the lymph from the scrotal skin and again unexpected avid radiotracer uptake in the axillae bilaterally. Findings were concluded as congenital hypoplasia of lymphatics in lower limbs, congenital lymphectasia/compensatory megalymphatics in scrotum and aberrant lymphatic pathway, possibly due to malfunctioning/nonfunctioning thoracic duct. PMID:23559718

  13. Efficient Project Delivery Using Lean Principles - An Indian Case Study

    NASA Astrophysics Data System (ADS)

    Kovvuri, P. Ramachandra Reddy; Sawhney, Anil; Ahuja, Ritu; Sreekumar, Aiswarya

    2016-03-01

    Construction industry in India is growing at a rapid pace. Along with this growth, the industry is facing numerous challenges that are making delivery of projects inefficient. Experts believe that capacity constraints in the industry need to be addressed immediately. Government has recommended `introduction of efficient technologies and modern management techniques' to increase the productivity of the industry. In this context, lean principles can act as a lever to make project delivery more efficient and provide the much needed impetus to the Indian construction sector. Around the globe lean principles are showing positive results on the projects. Project teams are reporting improvements in construction time, cost and quality along with softer benefits of enhanced collaboration, coordination and trust in project teams. Can adoption of lean principles provide similar benefits in the Indian construction sector? This research was conducted to answer this question. Using an action research approach a key lean construction tool called Last Planner System (LPS) was tested on a large Indian construction project. The work described in this work investigates the improvements achieved in project delivery by adopting LPS in Indian construction sector. Comparison in pre- and post-implementation data demonstrates increase in the certainty of work-flow and improves schedule compliance. This is measured through a simple LPS metric called percent plan complete. Explicit improvements in schedule performance are seen during 8 week LPS implementation along with implicit improvements in coordination, collaboration and trust in the project team. This work reports the findings of LPS implementation on the case study project outlining the barriers and drivers to adoption, strategies needed to ensure successful implementation and roadmap for implementation. Based on the findings the authors envision that lean construction can make project delivery more efficient in India.

  14. Otolaryngology resident workflow: a time-motion and efficiency study.

    PubMed

    Victores, Andrew; Roberts, Jess; Sturm-O'Brien, Angela; Victores, Nina; Uecker, Wil; Alford, Bobby; Takashima, Mas

    2011-05-01

    To investigate workflow in an otolaryngology-head and neck surgery residency program over 1 year and identify areas for improvement in the efficiency of resident education and training. Time-motion study. An urban, county hospital and a Veterans Affairs medical center hospital. Subjects and Methods. Eight otolaryngology residents (4 residents at postgraduate year [PGY] 2 and 4 at PGY 4) were studied using direct observations early and late in the 2008-2009 academic year. Resident activities were categorized, and a database program was generated for a handheld computer to facilitate time entry. Resident activities were classified into a taxonomy of tasks and their educational value was assessed. For each PGY level studied, observations were made for clinic and operative days. Residents spent their day on direct patient care (43.5%), indirect patient care (33.7%), didactic education (9.6%), personal activities (7.5%), and transit (5.8%), with activities of marginal educational value consuming 16% of their time. Major inefficiencies included managing administrative tasks, scheduling, and technical difficulties. On average, residents devoted significantly more time to marginal tasks on clinic days (19%) than on operative days (12%; P < .001). These data were compared with previously published data obtained during the pre–Accreditation Council for Graduate Medical Education (ACGME) duty hour mandates era. This study evaluates resident workflow and efficiency over the course of a PGY in an ACGME-accredited otolaryngology residency program. By understanding the time motion of residents, interruptions and inefficiencies in workflow can be identified to direct future changes to enhance resident education and training in the era of the ACGME duty hours mandate.

  15. A twin study of weight loss and metabolic efficiency.

    PubMed

    Hainer, V; Stunkard, A; Kunesová, M; Parízková, J; Stich, V; Allison, D B

    2001-04-01

    To assess the genetic contribution to determinants of therapeutic weight loss in obese female identical twins. Subjects were studied for 40 days on an inpatient unit in three phases: 7 baseline days; 28 days of weight reduction by a very low calorie diet (1.6 MJ per day); and 5 days after weight reduction. Fourteen pairs of premenopausal obese female identical twins (age: 39.0+/-1.7 y; body weight (BW): 93.9+/-21.2 kg; body mass index (BMI): 34.2+/-7.8 kg/m2). : Body composition by hydrodensitometry and resting metabolic rate by indirect calorimetry were assessed before and after weight loss. : There was great variability among pairs in loss of weight (5.9-12.4 kg) and body fat (3.1-12.4 kg). By contrast, the intraclass correlation (ICC) within twin pairs was 0.85, P<0.001 for weight and 0.88, P<0.001 for body fat. A measure of metabolic efficiency, calculated as the difference between 'estimated' and 'measured' energy deficit showed high intrapair correlation (ICC=0.77; P<0.001). The high correlation in metabolic efficiency within twin pairs in response to therapeutic weight loss suggests a strong genetic contribution.

  16. (Energy efficiency improvement studies for Costa Rica and Guatemala)

    SciTech Connect

    Waddle, D.B.

    1990-05-30

    I travelled to San Jose, Cost Rica, on May 20, 1990 to report on the progress of the Integrated Power Sector Efficiency Analysis Project to the Instituto Costarrincense de Electricidad, and to USAID/San Jose. I also discussed the progress and plans for the CONELECTRICAS Small Hydroelectric Project supported by ORNL through the Renewable Energy Applications and Training Project. Both projects are proceeding on schedule. ORNL will complete further supply side analysis after comments are submitted by ICE, with respect to the information provided on this visit. The CONELECTRICAS project will require further ORNL input to assist in optimization of equipment selection and to perform the required financial and economic cost analyses. I travelled to Guatemala City on May 22, 1990. I met with Instituto Nacional de Electricacion (INDE) to discuss the findings and recommendations of the Electric Power Utility Efficiency Improvement Study undertaken in February, 1990. I also met with Mario Funes to discuss future ORNL assistance to ROCAP in support of the CARES project as well as other ROCAP energy initiatives.

  17. Online crowdsourcing for efficient rating of speech: A validation study

    PubMed Central

    Byun, Tara McAllister; Halpin, Peter F.; Szeredi, Daniel

    2015-01-01

    Blinded listener ratings are essential for valid assessment of interventions for speech disorders, but collecting these ratings can be time-intensive and costly. This study evaluated the validity of speech ratings obtained through online crowdsourcing, a potentially more efficient approach. 100 words from children with /r/ misarticulation were electronically presented for binary rating by 35 phonetically trained listeners and 205 naïve listeners recruited through the Amazon Mechanical Turk (AMT) crowdsourcing platform. Bootstrapping was used to compare different-sized samples of AMT listeners against a “gold standard” (mode across all trained listeners) and an “industry standard” (mode across bootstrapped samples of 3 trained listeners). There was strong overall agreement between trained and AMT listeners. The “industry standard” level of performance was matched by bootstrapped samples with n = 9 AMT listeners. These results support the hypothesis that valid ratings of speech data can be obtained in an efficient manner through AMT. Researchers in communication disorders could benefit from increased awareness of this method. PMID:25578293

  18. Experimental study on mixing efficiency in water supply rectangular tanks

    NASA Astrophysics Data System (ADS)

    Bateman, A.; Medina, V.; Mujal, A.

    2009-04-01

    Phenomenon of mixing in drinking water storage tanks and reservoirs has a direct effect on the quality of water. Creation of poor mixing zones and volume stratification can have negative effects in public health. The design of a storage tank must consider the conditions of the inlet and outlets, and also their orientation (vertical or horizontal) to prevent the formation of these zones. Experiments done in a reduced scaled-model with a rectangular base and three different inlets (two waterfalls and a pipe inlet) had the objective to decide which of these inlets achieved the best mixing efficiency. Four situations were considered while three entrances, two unsteady: filling and drawing, and two steady with different outlets. Moreover the effects of columns that support the roof of the tank were studied by running the three entrances with and without columns in the four situations. Neglecting the viscous scale effects, the time taken to mix the volume stored depends on the distance between the inlet and the opposite wall as though as its orientation. Taking into account the whole tank columns have a negative effect on mixing efficiency although they divide the flux and create local zones of turbulence around them, increasing local mixing. Using a digital treating image technique the results are found in a quantitative way.

  19. Development of indazolylpyrimidine derivatives as high-affine EphB4 receptor ligands and potential PET radiotracers.

    PubMed

    Ebert, Kristin; Wiemer, Jens; Caballero, Julio; Köckerling, Martin; Steinbach, Jörg; Pietzsch, Jens; Mamat, Constantin

    2015-09-01

    Due to their essential role in the pathogenesis of cancer, members of the Eph (erythropoietin-producing hepatoma cell line-A2) receptor tyrosine kinase family represent promising candidates for molecular imaging. Thus, the development and preparation of novel radiotracers for the noninvasive imaging of the EphB4 receptor via positron emission tomography (PET) is described. First in silico investigations with the indazolylpyrimidine lead compound which is known to be highly affine to EphB4 were executed to identify favorable labeling positions for an introduction of fluorine-18 to retain the affinity. Based on this, reference compounds as well as precursors were developed and labeled with carbon-11 and fluorine-18, respectively. For this purpose, a protecting group strategy essentially had to be generated to prevent unwanted methylation and to enable the introduction of fluorine-18. Further, a convenient radiolabeling strategy using [(11)C]methyl iodide was established which afforded the isotopically labeled radiotracer in 30-35% RCY (d.c.) which is identical with the original inhibitor molecule. A spiro ammonium precursor was prepared for radiolabeling with fluorine-18. Unfortunately, the labeling did not lead to the desired (18)F-radiotracer under the chosen conditions.

  20. Imaging cardiac SCN5A using the novel F-18 radiotracer radiocaine

    PubMed Central

    Hooker, Jacob M.; Strebl, Martin G.; Schroeder, Frederick A.; Wey, Hsiao-Ying; Ambardekar, Amrut V.; McKinsey, Timothy A.; Schoenberger, Matthias

    2017-01-01

    The key function of the heart, a well-orchestrated series of contractions, is controlled by cardiac action potentials. These action potentials are initiated and propagated by a single isoform of voltage gated sodium channels – SCN5A. However, linking changes in SCN5A expression levels to human disease in vivo has not yet been possible. Radiocaine, an F-18 radiotracer for positron emission tomography (PET), is the first SCN5A imaging agent in the heart. Explants from healthy and failing human hearts were compared using radiocaine autoradiography to determine that the failing heart has ~30% lower SCN5A levels - the first evidence of changes in SCN5A expression in humans as a function of disease. Paving the way for translational imaging, radiocaine proved to exhibit high in vivo specific binding to the myocardium of non-human primates. We envision that SCN5A measurements using PET imaging may serve as a novel diagnostic tool to stratify arrhythmia risk and assess for progression of heart failure in patients with a broad spectrum of cardiovascular diseases. PMID:28205593

  1. Agonist signalling properties of radiotracers used for imaging of dopamine D2/3 receptors

    PubMed Central

    2014-01-01

    Background Dopamine D2/3 receptor (D2/3R) agonist radiopharmaceuticals are considered superior to antagonists to detect dopamine release, e.g. induced by amphetamines. Agonists bind preferentially to the high-affinity state of the dopamine D2R, which has been proposed as the reason why agonists are more sensitive to detect dopamine release than antagonist radiopharmaceuticals, but this theory has been challenged. Interestingly, not all agonists similarly activate the classic cyclic adenosine mono phosphate (cAMP) and the ?-arrestin-2 pathway, some stimulate preferentially one of these pathways; a phenomenon called biased agonism. Because these pathways can be affected separately by pathologies or drugs (including dopamine releasers), it is important to know how agonist radiotracers act on these pathways. Therefore, we characterized the intracellular signalling of the well-known D2/3R agonist radiopharmaceuticals NPA and PHNO and of several novel D2/3R agonists. Methods cAMP accumulation and ?-arrestin-2 recruitment were measured on cells expressing human D2R. Results All tested agonists showed (almost) full agonism in both pathways. Conclusions The tested D2/3R agonist radiopharmaceuticals did not exhibit biased agonism in vitro. Consequently, it is likely that drugs (including psychostimulants like amphetamines) and/or pathologies that influence the cAMP and/or the ?-arrestin-2 pathway may influence the binding of these radiopharmaceuticals. PMID:25977878

  2. PET and SPECT Radiotracers to Assess Function and Expression of ABC Transporters in Vivo

    PubMed Central

    Mairinger, Severin; Erker, Thomas; Müller, Markus; Langer, Oliver

    2013-01-01

    Adenosine triphosphate-binding cassette (ABC) transporters, such as P-glycoprotein (Pgp, ABCB1), breast cancer resistance protein (BCRP, ABCG2) and multidrug resistance-associated proteins (MRPs) are expressed in high concentrations at various physiological barriers (e.g. blood-brain barrier, blood-testis barrier, blood-tumor barrier), where they impede the tissue accumulation of various drugs by active efflux transport. Changes in ABC transporter expression and function are thought to be implicated in various diseases, such as cancer, epilepsy, Alzheimer’s and Parkinson’s disease. The availability of a non-invasive imaging method which allows for measuring ABC transporter function or expression in vivo would be of great clinical use in that it could facilitate the identification of those patients that would benefit from treatment with ABC transporter modulating drugs. To date three different kinds of imaging probes have been described to measure ABC transporters in vivo: i) radiolabelled transporter substrates ii) radiolabelled transporter inhibitors and iii) radiolabelled prodrugs which are enzymatically converted into transporter substrates in the organ of interest (e.g. brain). The design of new imaging probes to visualize efflux transporters is inter alia complicated by the overlapping substrate recognition pattern of different ABC transporter types. The present article will describe currently available ABC transporter radiotracers for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) and critically discuss strengths and limitations of individual probes and their potential clinical applications. PMID:21434859

  3. Detailed spatio-temporal solids concentration profiling during batch settling of activated sludge using a radiotracer.

    PubMed

    De Clercq, Jeriffa; Jacobs, Filip; Kinnear, David J; Nopens, Ingmar; Dierckx, Rudi A; Defrancq, Jacques; Vanrolleghem, Peter A

    2005-05-01

    In building and tuning good settling models for secondary clarifiers of wastewater treatment plants, there is a need for measured continuous solids concentration profiles during batch settling. Conventional measuring techniques have difficulties in recording this kind of data, either because they are invasive, or because of the low solids concentration and/or solids density of activated sludge. This paper investigates a novel non-invasive measurement technique borrowed from nuclear medicine, using a solids radiotracer and gamma cameras, to obtain solids concentration profiles during the batch settling of activated sludge, in a pilot-scale column with a height of 1m. The technique does not disturb the settling process, does not alter the settling characteristics, gives profiles every minute and every few millimeters, and is capable of measuring in a range of 0-25 g/l with high accuracy. Dynamic solids concentration profile measurements were performed for sludges of different wastewater treatment plants, and at different initial concentrations. The results show a quantitative representation of the settling process, and reveal hindered and compression settling.

  4. Bioavailability and distribution and of ceria nanoparticles in simulated aquatic ecosystems, quantification with a radiotracer technique.

    PubMed

    Lu, Kai; Zhang, Zhiyong; He, Xiao; Ma, Yuhui; Zhou, Kebin; Zhang, Haifeng; Bai, Wei; Ding, Yayun; Wu, Zhenqiang; Zhao, Yuliang; Chai, Zhifang

    2010-12-01

    Although the presence of manufactured nanoparticles in the aquatic environment is still largely undocumented, their release could certainly occur in the future, particularly via municipal treatment plant effluents of cities supporting nano-industries. To get an initial estimate of the environmental behavior of nanomaterials, we investigated the distribution and accumulation of ceria nanoparticles in simulated aquatic ecosystems which included aquatic plant, shellfish, fish, water, and sediment using a radiotracer technique. Radioactive ceria (141CeO2) nanoparticles with a diameter of ca. 7 nm were synthesized by a precipitation method and added to the simulated aquatic ecosystems. The results indicate that the concentration of ceria nanoparticles in water decreased to a steady-state value after 3 days; meanwhile, the concentrations of ceria nanoparticles in the aquatic plant and sediment increased to their highest values. The distribution and accumulation characteristics of ceria nanoparticles in various aquatic organisms were different. Ceratophyllum demersum showed a high ability of accumulation of ceria nanoparticles from water.

  5. Efficient methods for studying stochastic disease and population dynamics.

    PubMed

    Keeling, M J; Ross, J V

    2009-01-01

    Stochastic ecological and epidemiological models are now routinely used to inform management and decision making throughout conservation and public-health. A difficulty with the use of such models is the need to resort to simulation methods when the population size (and hence the size of the state space) becomes large, resulting in the need for a large amount of computation to achieve statistical confidence in results. Here we present two methods that allow evaluation of all quantities associated with one- (and higher) dimensional Markov processes with large state spaces. We illustrate these methods using SIS disease dynamics and studying species that are affected by catastrophic events. The methods allow the possibility of extending exact Markov methods to real-world problems, providing techniques for efficient parameterisation and subsequent analysis.

  6. Suitable scheme study of Chinese Building Energy Efficiency CDM Projects

    NASA Astrophysics Data System (ADS)

    Huang, Beijia; Yang, Haizhen; Wang, Shaoping; Wang, Feng

    2010-11-01

    China has great potential to develop Building Energy Efficiency Clean Development Mechanism (BEE CDM) projects, although have many challenges. Our results show that large-scale public buildings and urban residential buildings have relatively high BEE CDM potential, when comparing their characteristics to the CDM project requirements. The building enclosure, illumination energy conservation, air condition energy saving, solar thermal, and solar photovoltaic technology have relatively high application potential while considering the energy saving potential and marginal emission reduction cost. Case study of large-scale buildings shows that technology integration of building enclosure, illumination energy conservation, air condition energy saving, solar thermal can reduce required building number to 130 in order to meet the 1×105 tCO2 e/a reduction criteria. Some suggestions are also given in this paper.

  7. Experimental Study of Internal Gettering Efficiency of Iron in Silicon

    NASA Astrophysics Data System (ADS)

    Haarahiltunen, A.; Yli-Koski, M.; Väinölä, H.; Palokangas, M.; Saarnilehto, E.; Sinkkonen, J.

    2004-01-01

    We have studied internal gettering efficiency of iron in silicon by Deep Level Transient Spectroscopy (DLTS) and standard lifetime methods (SPV, µPCD). Conventional high low high anneals were performed to produce a series of wafers with varying denuded zone (DZ) width and oxygen precipitation density. The wafers were intentionally iron contaminated to a level of about 3 5*1013cm 3. After contamination the wafers were annealed at 900°C and then slowly cooled to 850, 800, 750, 700 or 600°C. After cooling the remaining interstitial iron concentration was measured by SPV, µ-PCD and DLTS. The experimental results are compared with simulations. Our results indicate that with this contamination level, the gettering is effective only at temperatures below 750°C when iron is supersaturated over a factor of twenty. For temperatures above 750°C the gettering is limited by iron precipitation in the bulk.

  8. Characterization of fast-decaying PET radiotracers solely through LC-MS/MS of constituent radioactive and carrier isotopologues

    PubMed Central

    2013-01-01

    Background The characterization of fast-decaying radiotracers that are labeled with carbon-11 (t1/2 = 20.38 min), including critical measurement of specific radioactivity (activity per mole at a specific time) before release for use in positron-emission tomography (PET), has relied heavily on chromatographic plus radiometric measurements, each of which may be vulnerable to significant errors. Thus, we aimed to develop a mass-specific detection method using sensitive liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) for identifying 11C-labeled tracers and for verifying their specific radioactivities. Methods The LC-MS/MS was tuned and set up with methods to generate and measure the product ions specific for carbon-11 species and M + 1 carrier (predominantly the carbon-13 isotopologue) in four 11C-labeled tracers. These radiotracers were synthesized and then analyzed before extensive carbon-11 decay. The peak areas of carbon-11 species and M + 1 carrier from the LC-MS/MS measurement and the calculated abundances of carbon-12 carrier and M + 1 radioactive species gave the mole fraction of carbon-11 species in each sample. This value upon multiplication with the theoretical specific radioactivity of carbon-11 gave the specific radioactivity of the radiotracer. Results LC-MS/MS of each 11C-labeled tracer generated the product ion peaks for carbon-11 species and M + 1 carrier at the expected LC retention time. The intensity of the radioactive peak diminished as time elapsed and was undetectable after six half-lives of carbon-11. Measurements of radiotracer-specific radioactivity determined solely by LC-MS/MS at timed intervals gave a half-life for carbon-11 (20.43 min) in excellent agreement with the value obtained radiometrically. Additionally, the LC-MS/MS measurement gave specific radioactivity values (83 to 505 GBq/μmol) in good agreement with those from conventional radiometric methods. Conclusions 11C-Labeled tracers were

  9. Characterization of fast-decaying PET radiotracers solely through LC-MS/MS of constituent radioactive and carrier isotopologues.

    PubMed

    Shetty, H Umesha; Morse, Cheryl L; Zhang, Yi; Pike, Victor W

    2013-01-12

    The characterization of fast-decaying radiotracers that are labeled with carbon-11 (t1/2 = 20.38 min), including critical measurement of specific radioactivity (activity per mole at a specific time) before release for use in positron-emission tomography (PET), has relied heavily on chromatographic plus radiometric measurements, each of which may be vulnerable to significant errors. Thus, we aimed to develop a mass-specific detection method using sensitive liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) for identifying 11C-labeled tracers and for verifying their specific radioactivities. The LC-MS/MS was tuned and set up with methods to generate and measure the product ions specific for carbon-11 species and M + 1 carrier (predominantly the carbon-13 isotopologue) in four 11C-labeled tracers. These radiotracers were synthesized and then analyzed before extensive carbon-11 decay. The peak areas of carbon-11 species and M + 1 carrier from the LC-MS/MS measurement and the calculated abundances of carbon-12 carrier and M + 1 radioactive species gave the mole fraction of carbon-11 species in each sample. This value upon multiplication with the theoretical specific radioactivity of carbon-11 gave the specific radioactivity of the radiotracer. LC-MS/MS of each 11C-labeled tracer generated the product ion peaks for carbon-11 species and M + 1 carrier at the expected LC retention time. The intensity of the radioactive peak diminished as time elapsed and was undetectable after six half-lives of carbon-11. Measurements of radiotracer-specific radioactivity determined solely by LC-MS/MS at timed intervals gave a half-life for carbon-11 (20.43 min) in excellent agreement with the value obtained radiometrically. Additionally, the LC-MS/MS measurement gave specific radioactivity values (83 to 505 GBq/μmol) in good agreement with those from conventional radiometric methods. 11C-Labeled tracers were characterized at a fundamental level

  10. Federal energy efficiency and water conservation funding study

    SciTech Connect

    1998-01-01

    This report contains the results of a study required by section 162 of the Energy Policy Act of 1992 (EPAct). It outlines options for financing energy and water conservation measures at Federal facilities as required by Part 3 of Title V of the National Energy Policy and Conservation Act (NECPA) (42 U.S.C. 8251 et seq.) as amended by EPAct. It addresses: (1) the estimated Federal financial investment necessary to install energy and water conservation measures to meet NECPA and Executive Order requirements; (2) the use of revolving funds and other funding mechanisms which offer stable, long-term financing of energy and water conservation measures; and (3) the means for capitalizing such funds. On March 8, 1994, President Clinton signed Executive Order 12902. This Executive Order is an aggressive mandate to improve energy efficiency and water conservation in Federal buildings nationwide. This Executive Order is designed to meet and exceed requirements for Federal energy and water efficiency that were contained in section 152 of EPAct. Section 152 mandated that Federal agencies use all cost effective measures with less than a ten year payback to reduce energy consumption in their facilities by 20% by the year 2000 compared to 1985 levels. In addition, Executive Order 12902 established a requirement to use cost effective measures to reduce energy use by fiscal year 2005 by 30% compared to 1985 energy use. This report provides estimates for the energy and water conservation investments needed to achieve the NECPA and Executive Order goals as well as estimates for the contribution from various funding sources and a review of the mechanisms for funding these investments.

  11. Imaging the Cytokine Receptor CXCR4 in Atherosclerotic Plaques with the Radiotracer (68)Ga-Pentixafor for PET.

    PubMed

    Hyafil, Fabien; Pelisek, Jaroslav; Laitinen, Iina; Schottelius, Margret; Mohring, Miriam; Döring, Yvonne; van der Vorst, Emiel P C; Kallmayer, Michael; Steiger, Katja; Poschenrieder, Andreas; Notni, Johannes; Fischer, Johannes; Baumgartner, Christine; Rischpler, Christoph; Nekolla, Stephan G; Weber, Christian; Eckstein, Hans-Henning; Wester, Hans-Jürgen; Schwaiger, Markus

    2017-03-01

    (68)Ga-pentixafor is a radiotracer for PET that binds with nanomolar affinity to CXCR4. The CXCR4 receptor is expressed at the surface of inflammatory cells. The objective of the study was to analyze the ability of radiolabeled pentixafor to detect CXCR4 expression on inflammatory cells present in atherosclerotic plaques of an experimental rabbit model. Methods: Atherosclerotic plaques were induced by endothelial abrasion of the right carotid artery and abdominal aorta of 7 rabbits fed an atherogenic diet. Five noninjured rabbits fed a chow diet were used as controls. Rabbits were imaged on a PET/MR system after injection of (68)Ga-pentixafor (15 MBq/kg). Vascular signal was quantified as tissue-to-background ratio (TBR). Biodistribution and autoradiographic studies were performed 1 h after injection of (125)I-pentixafor (7.5 MBq/kg). In addition, blocking studies were performed in 2 atherosclerotic rabbits with preinjection of the CXCR4 inhibitor AMD3100. Tracer uptake was quantified on arterial cryosections using autoradiography and compared with CXCR4 and RAM-11 (macrophage) expression on adjacent histologic sections. Results: One hour after injection of (68)Ga-pentixafor, strong signals were detected in vivo with PET/MR imaging in atherosclerotic plaques of the abdominal aorta and right carotid artery as compared with normal control arteries (mean TBR = 1.95 ± 0.51 vs. 1.22 ± 0.25 and mean TBR = 1.24 ± 0.38 vs. 0.96 ± 0.37, respectively; P < 0.05 for both). Blocking studies with preinjection of a CXCR4 inhibitor reduced (125)I-pentixafor uptake in atherosclerotic plaques by approximately 40%. (125)I-pentixafor uptake in the vessel wall on autoradiographies was located in macrophage-rich regions of atherosclerotic plaques and correlated with the intensity of CXCR4 expression on corresponding cryosections (r(2) = 0.61; P < 0.05). Conclusion:(68)Ga-pentixafor allows for the noninvasive detection of CXCR4 expression in the vessel wall with PET and emerges as a

  12. Methodological considerations regarding the use of inorganic 197Hg(II) radiotracer to assess mercury methylation potential rates in lake sediment

    USGS Publications Warehouse

    Perez, Catan S.; Guevara, S.R.; Marvin-DiPasquale, M.; Magnavacca, C.; Cohen, I.M.; Arribere, M.

    2007-01-01

    Methodological considerations on the determination of benthic methyl-mercury (CH3Hg) production potentials were investigated on lake sediment, using 197Hg radiotracer. Three methods to arrest bacterial activity were compared: flash freezing, thermal sterilization, and ??-irradiation. Flash freezing showed similar CH3Hg recoveries as thermal sterilization, which was both 50% higher than the recoveries obtained with ??-ray irradiation. No additional radiolabel was recovered in kill-control samples after an additional 24 or 65 h of incubation, suggesting that all treatments were effective at arresting Hg(II)-methylating bacterial activity, and that the initial recoveries are likely due to non-methylated 197Hg(II) carry-over in the organic extraction and/or [197Hg]CH3Hg produced via abiotic reactions. Two CH3Hg extraction methods from sediment were compared: (a) direct extraction into toluene after sediment leaching with CuSO4 and HCl and (b) the same extraction with an additional back-extraction step to thiosulphate. Similar information was obtained with both methods, but the low efficiency observed and the extra work associated with the back-extraction procedure represent significant disadvantages, even tough the direct extraction involves higher Hg(II) carry over. ?? 2007 Elsevier Ltd. All rights reserved.

  13. Development of a high efficiency and high resolution Compton probe for prostate imaging

    NASA Astrophysics Data System (ADS)

    Bernabeu, J.; Clinthorne, N. H.; Dewaraja, Y.; Lacasta, C.; Llosá, G.; Mikuž, M.; Roe, S.; Rogers, W. L.; Studen, A.; Weilhammer, P.; Zhang, L.; Žontar, D.

    2004-07-01

    The ability to diagnose early prostate cancer has outpaced imaging methods for accurate localization and staging of the disease. A precise determination of the extent of local disease is difficult and, unfortunately, present imaging instrumentation employing radiotracer techniques (PET, SPECT, planar scintigraphy) is limited in its ability to provide detailed information when imaging the prostate due to modest spatial resolution, often poor counting efficiency, and photon attenuation. The innovation in the work described here is the use of a silicon prostate probe based on the principle of the Compton scatter camera. Simulation studies show that the endorectal prostate probe will enhance the spatial resolution by a factor 4-5 and, simultaneously, provide a gain in efficiency of a factor 16-40 over conventional nuclear medicine cameras. The ongoing tasks are focused on the design optimization of a Compton probe prototype.

  14. Synthesis and Evaluation of [11C]LY2795050 as a Novel Kappa Opioid Receptor Antagonist Radiotracer for PET Imaging

    PubMed Central

    Zheng, Ming-Qiang; Nabulsi, Nabeel; Kim, Su Jin; Tomasi, Giampaolo; Lin, Shu-fei; Mitch, Charles; Quimby, Steven; Barth, Vanessa; Rash, Karen; Masters, John; Navarro, Antonio; Seest, Eric; Morris, Evan E.; Carson, Richard E.; Huang, Yiyun

    2013-01-01

    Kappa opioid receptors (KOR) are believed to be involved in the pathophysiology of depression, anxiety disorders, drug abuse and alcoholism. To date, only one tracer, the kappa opioid receptor agonist [11C]GR103545, has been reported to be able to image KOR in primates. The goal of the present study was to synthesize the selective KOR antagonist [11C]LY2795050 and evaluate its potential as a PET tracer to image KOR in vivo. METHODS In vitro binding affinity of LY2795050 was measured in radioligand competition binding assays. Ex vivo experiments were conducted using microdosing of the unlabelled ligand in Sprague-Dawley rats, as well as wild-type and KOR knock-out mice, to assess the ligand’s potential as a tracer candidate. Imaging experiments with [11C]LY2795050 in monkeys were carried out on the Focus-220 PET scanner with arterial blood input function measurement. Binding parameters were determined with kinetic modeling analysis. RESULTS LY2795050 displays full antagonist activity and high binding affinity and selectivity for KOR. Microdosing studies in rodents and ex vivo analysis of tissue concentrations with LC/MS/MS identified LY2795050 as an appropriate tracer candidate able to provide specific binding signals in vivo. [11C]LY2795050 was prepared in an average yield of 12% and >99% radiochemical purity. In rhesus monkeys, [11C]LY2795050 displayed a moderate rate of peripheral metabolism, with ∼40% of parent compound remaining at 30 min postinjection. In the brain, [11C]LY2795050 displayed fast uptake kinetics (regional activity peak times < 20 min) and an uptake pattern consistent with the distribution of KOR in primates. Pretreatment with naloxone (1 mg/kg, iv) resulted in a uniform distribution of radioactivity. Further, specific binding of [11C]LY2795050 was reduced by the selective KOR antagonist LY2456302 in a dose-dependent manner. CONCLUSION [11C]LY2795050 displayed favorable pharmacokinetic properties and binding profiles in vivo, and therefore

  15. [{sup 11}C]d-threo-Methylphenidate, a new radiotracer for the dopamine transporter. Characterization in baboon and human brain

    SciTech Connect

    Ding, Y.S.; Volkow, N.D.; Fowler, J.S.

    1995-05-01

    dl-threo Methylphenidate (MP, Ritalin) is a psychostimulant drug which binds to the dopamine transporter (DAT). We evaluated [{sup 11}C]d-threo-methylphenidate ([{sup 11}C]d-MP), the more active enantiomer, as a radiotracer for the DAT in baboons and human brain. Stereoselectivity, saturability and pharmacological specificity and reproducibility were examined. Stereoselectivity was examined in baboons by comparing [{sup 11C}]d-MP,[{sup 11}C]l-MP and [{sup 11}C]dl-MP. Unlabeled MP was used to assess the reversibility and saturability of the binding. GBR 12909,{beta}-(4-iodophenyl)tropane-2-carboxylic acid methyl ester ({beta}-CIT), tomoxetine and citalopram were used to assess the specificity of the binding. The ratios between the radioactivity in the striatum to that in cerebellum (ST/CB) were 3.3,2.2 and 1.1 for [{sup 11}C]d-MP,[{sup 11}C]dl-MP and [{sup 11}C]l-MP respectively. Most of the striatal binding of [{sup 11}C]d-threo-MP was displaced by injection of nonradioactive MP demonstrating reversibility. Pretreatment with MP (0.5 mg/kg), GBR12909 (1.5 mg/kg) or {beta}-CIT (0.3 mg/kg) reduced ST/CB by about 60% and the ratios of distribution volumes at the steady-state for the triatum to cerebellum (DV{sub st/}DV{sub cb}) by about 50%. Pretreatment with tomoxetine (3.0 mg/kg) or citalopram (2.0 mg/kg), inhibitors of the norepinephrine and serotonin transporter, had no effect. Studies of [{sup 11}C]d-MP in the human brain showed highest uptake in basal ganglia with a half clearance time of about 60 minutes. Repeated studies in 6 normal human subjects showed differences in DV{sub st/}DV{sub cb} between -7% and 8%. MP pretreatment decreased BG but no cortical or cerebellar binding and reduced Bmax/Kd by 91%.

  16. A theoretical study of the efficiency of the general circulation

    NASA Technical Reports Server (NTRS)

    Schulman, L. L.

    1977-01-01

    The paper examines the problem of explaining the atmospheric efficiency, or equivalently, the rate of generation of available potential energy (APE) by diabatic heating. Attention is focused on determining the maximum possible rate of generation of APE and its accompanying temperature field, which does not require a knowledge of the atmospheric motions leading to temperature distribution. Qualitative and quantitative results indicate that the atmosphere may be operating within approximately a factor of 2 of its maximum efficiency. The general circulation may be operating at nearly its maximum efficiency.

  17. Efficiency of thermography in the study of hydrological connectivity

    NASA Astrophysics Data System (ADS)

    Cantreul, Vincent; Burgeon, Victor; Triquet, Johan; Tuerlinck, Manon; Vaelen, Guillaume; Leemans, Vincent; Degré, Aurore

    2016-04-01

    Hydrologic connectivity is an emerging concept which permits deeper understanding of catchments behavior. However, the measurements of functional connectivity is complex and still needs new developments in order to approach the « dynamic » part of the story. This study aims at assessing the efficiency of thermography to analyze hydrologic connectivity in an agricultural catchment in Belgium (loamy soils). Tests have been performed on experimental tubs at first and on field at second. Under controlled conditions, hot milk was spread on an experimental tub with bare soil and grass. The hot milk permits to compare color tracer with thermic one. The results are quite good. The binarization of pictures from usual camera and from thermic one gives similar percentage of runoff coverage at same locations. The mean difference is about 8% for bare soils and 10% for planted grass. There is a slight overestimation with thermic camera because of time delay of soil cooling after milk passing. In the same time in the planted grass, there are some runoff pixels which are hidden by vegetation. On field, blue colored water was used to simulate a rainfall on a field covered with mustard and on the same field without any coverage. Where runoff flows, the soil appears warmer because of heat extracted by water in the soil. The results comparing visual and thermic pictures are more nuanced. The mean difference reaches 30% on bare soil. Indeed, (i) the rainfall drops seem to hide the runoff during the rain; (ii) the vegetation density (mustard) is quite a problem for runoff detection. However, the difference between successive time pictures permits to distinguish flow paths easily. In conclusion, thermography stands as a good alternative for connectivity study. It's obviously a preliminary study which gives some indications of the possible use of thermography. At present, we are testing real rainfalls (different types) with different camera's positions and different land use (different

  18. Detective quantum efficiency (DQE) in PET scanners: A simulation study.

    PubMed

    Karpetas, George E; Michail, Christos M; Fountos, George P; Kalyvas, Nektarios I; Valais, Ioannis G; Kandarakis, Ioannis S; Panayiotakis, George S

    2017-07-01

    The aim of the present study is to introduce the detective quantum efficiency (DQE) for the image quality assessment of positron emission tomography (PET) scanners. For this purpose, a thin layer chromatography (TLC) plane source was simulated using a previously validated, scanner and source geometry, Monte Carlo (MC) model. The model was developed with the Geant4 application for tomographic emission (GATE) MC package and reconstructed images obtained with the software for tomographic image reconstruction (STIR), with cluster computing. The GE Discovery ST PET scanner was simulated by using a previously validated code. A plane source consisting of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrate, immersed in 18F-FDG bath solution (1MBq). Image quality was assessed in terms of the modulation transfer function (MTF) and the normalized noise power spectrum (NNPS) in order to obtain the detective quantum efficiency (DQE). MTF curves were estimated from transverse reconstructed images of the plane source, whereas the NNPS data were estimated from the corresponding coronal images. Images were reconstructed by the maximum likelihood estimation ordered subsets maximum a posteriori one step late (MLE)-OS-MAP-OSL algorithm, by using various subsets 1-21) and iterations 1-20). MTF values were found to increase up to the 12th iteration whereas remain almost constant thereafter. However, the range of the increase in the MTF is limited as the number of subsets increases. The noise levels were found to increase with the corresponding increase of both the number of iterations and subsets. The maximum NNPS value (0.517mm(2)) was observed for the 420 MLEM-equivalent iterations reconstructed image at 0cycles/mm. Finally DQE values were found to increase for spatial frequencies up to 0.038cycles/mm and to decrease thereafter with the corresponding increase in both number of iterations and subsets. The maximum DQE value (0.48 at 0.038cycles/mm) was

  19. In Vivo Quantification of Human Serotonin 1A Receptor Using 11C-CUMI-101, an Agonist PET Radiotracer

    PubMed Central

    Milak, Matthew S.; DeLorenzo, Christine; Zanderigo, Francesca; Prabhakaran, Jaya; Kumar, J.S. Dileep; Majo, Vattoly J.; Mann, J. John; Parsey, Ramin V.

    2013-01-01

    The serotonin (5-hydroxytryptamine, or 5-HT) type 1A receptor (5-HT1AR) is implicated in the pathophysiology of numerous neuropsychiatric disorders. We have published the initial evaluation and reproducibility in vivo of [O-methyl-11C]2-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5 (2H,4H)dione (11C-CUMI-101), a novel 5-HT1A agonist radiotracer, in Papio anubis. Here, we report the optimal modeling parameters of 11C-CUMI-101 for human PET studies. Methods PET scans were obtained for 7 adult human volunteers. 11C-CUMI-101 was injected as an intravenous bolus, and emission data were collected for 120 min in 3-dimensional mode. We evaluated 10 different models using metabolite-corrected arterial input functions or reference region approaches and several outcome measures. Results When using binding potential (BPF = Bavail/KD [total available receptor concentration divided by the equilibrium dissociation constant]) as the outcome measure, the likelihood estimation in the graphical analysis (LEGA) model performed slightly better than the other methods evaluated at full scan duration. The average test–retest percentage difference was 9.90% ± 5.60%. When using BPND (BPND = fnd × Bavail/KD; BPND equals the product of BPF and fnd [free fraction in the nondisplaceable compartment]), the simplified reference tissue method (SRTM) achieved the lowest percentage difference and smallest bias when compared with nondisplaceable binding potential obtained from LEGA using the metabolite-corrected plasma input function (r2 = 0.99; slope = 0.92). The time–stability analysis indicates that a 120-min scan is sufficient for the stable estimation of outcome measures. Voxel results were comparable to region-of-interest–based analysis, with higher spatial resolution. Conclusion On the basis of its measurable and stable free fraction, high affinity and selectivity, good blood–brain barrier permeability, and plasma and brain kinetics, 11C-CUMI-101 is

  20. Pharmacokinetic evaluation of the tau PET radiotracer 18F-T807 (18F-AV-1451) in human subjects

    PubMed Central

    Wooten, Dustin W.; Guehl, Nicolas J.; Verwer, Eline E.; Shoup, Timothy M.; Yokell, Daniel L.; Zubcevik, Nevena; Vasdev, Neil; Zafonte, Ross D.; Johnson, Keith A.; Fakhri, Georges El; Normandin, Marc D.

    2017-01-01

    18F-T807 is a PET radiotracer developed for imaging tau protein aggregates, which are implicated in neurological disorders including Alzheimer's disease (AD) and traumatic brain injury (TBI). The current study characterizes 18F-T807 pharmacokinetics in human subjects using dynamic PET imaging and metabolite-corrected arterial input functions. Methods Nine subjects (4 control, 3 with history of TBI, 2 mild cognitive impairment (MCI) due to suspected AD) underwent dynamic PET imaging for up to 120 minutes after bolus injection of 18F-T807 with arterial blood sampling. Total volume of distribution (VT) was estimated using compartmental modeling (one- and two-tissue configurations) and graphical analysis techniques (Logan and MA1 regression methods). Reference region-based methods of quantification were explored including Logan distribution volume ratio (DVR) and static standardized uptake value ratio (SUVR) utilizing the cerebellum as a reference tissue. Results Percent unmetabolized 18F-T807 in plasma followed a single exponential with T1/2 of 17.0±4.2 minutes. Metabolite corrected plasma radioactivity concentration fit a bi-exponential (T1/2: 18.1±5.8; 2.4±0.5 minutes). 18F-T807 in gray matter peaked quickly (SUV >2 at ∼5 minutes). Compartmental modeling resulted in good fits and the two-tissue model with estimated blood volume correction (2Tv) performed best, particularly in regions with elevated binding. VT was greater in MCI subjects than controls in the occipital, parietal, and temporal cortices as well as the posterior cingulate gyrus, precuneus, and mesial temporal cortex. High focal uptake was found in the posterior corpus callosum of a TBI subject. Plots from Logan and MA1 graphical methods became linear by 30 minutes, yielding regional estimates of VT in excellent agreement with compartmental analysis and providing high quality parametric maps when applied in voxelwise fashion. Reference region based approaches including Logan DVR (t*=55 min) and SUVR

  1. Novel (99m)Tc(III) Complexes [(99m)TcCl(CDO)(CDOH)2B-R] (CDOH2 = Cyclohexanedione Dioxime) Useful as Radiotracers for Heart Imaging.

    PubMed

    Liu, Min; Fang, Wei; Liu, Shuang

    2016-11-16

    In this study, we evaluated seven new (99m)Tc(III) complexes [(99m)TcCl(CDO)(CDOH)2B-R] ((99m)Tc-2Fboroxime: R = 2-formylfuran-3-yl (2F); (99m)Tc-3Fboroxime: R = furan-3-yl (3F); (99m)Tc-5Fboroxime: R = 5-formyfuran-2-yl (5F); (99m)Tc-HPboroxime: R = 6-hydroxylpyridin-2-yl (HP); (99m)Tc-MPYboroxime: R = 5-methoxypyridin-3-yl (MPY); (99m)Tc-PMboroxime: R = 1,5-pyrimidin-3-yl (PM); and (99m)Tc-4PYboroxime: R = pyridin-4-yl (4PY)) for their potential as heart imaging agents. All new (99m)Tc(III) radiotracers except (99m)Tc-2Fboroxime were prepared with high radiochemical purity (RCP > 95%). The low RCP (∼75%) for (99m)Tc-2Fboroxime is most likely caused by steric hindrance from the 3-formyl group. Biodistribution and imaging studies were performed in SD rats. Planar image quantification was performed to compare their myocardial retention times. We found that the myocardial washout curves of new (99m)Tc(III) radiotracers were best fitted the biexponential decay function. The AUC (area under the curve) values followed the general trend: (99m)Tc-5Fboroxime (129 ± 6) > (99m)Tc-3Fboroxime (114 ± 11) > (99m)Tc-Teboroxime (104 ± 16) > (99m)Tc-MPYboroxime (92 ± 18) > (99m)Tc-4PYboroxime (77 ± 10) > (99m)Tc-PMboroxime (68 ± 14) ≈ (99m)Tc-HPboroxime (62 ± 14). The 2 min heart uptake values from biodistribution studies follow the ranking order of (99m)Tc-5Fboroxime (3.75 ± 0.15%ID/g) ≈ (99m)Tc-MPYboroxime (3.73 ± 0.24%ID/g) > (99m)Tc-PMboroxime (3.47 ± 0.15%ID/g) ≈ (99m)Tc-3Fboroxime ≈ (3.25 ± 0.77%ID/g). The 5 min heart uptake of (99m)Tc-5Fboroxime (3.91 ± 0.09%ID/g) was almost identical to its 2 min heart uptake (3.75 ± 0.15%ID/g), and its 15 min heart uptake value (2.83 ± 0.08%ID/g) compared well to the 2 min heart uptake of (99m)Tc-Teboroxime (3.00 ± 0.37%ID/g). It took ∼5 min for (99m)Tc-5Fboroxime to approach the 1 min heart uptake value of (99m)Tc-Teboroxime (∼3.5% ID/g) and ∼9.5 min to reach the 2 min heart uptake value of (99m

  2. In vivo imaging of Aminopeptidase N (CD13) receptors in experimental renal tumors using the novel radiotracer (68)Ga-NOTA-c(NGR).

    PubMed

    Máté, Gábor; Kertész, István; Enyedi, Kata Nóra; Mező, Gábor; Angyal, János; Vasas, Nikolett; Kis, Adrienn; Szabó, Éva; Emri, Miklós; Bíró, Tamás; Galuska, László; Trencsényi, György

    2015-03-10

    Aminopeptidase N (APN/CD13) plays an important role in tumor neoangiogenic process and the development of metastases. Furthermore, it may serve as a potential target for cancer diagnosis and therapy. Previous studies have already shown that asparagine-glycine-arginine (NGR) peptides specifically bind to APN/CD13. The aim of the study was to synthesize and investigate the APN/CD13 specificity of a novel (68)Ga-labeled NOTA-c(NGR) molecule in vivo using miniPET. c[KNGRE]-NH2 peptide was conjugated with p-SCN-Bn-NOTA and was labeled with Ga-68 ((68)Ga-NOTA-c(NGR)). Orthotopic and heterotopic transplanted mesoblastic nephroma (NeDe) bearing Fischer-344 rats were prepared, on which biodistribution studies and miniPET scans were performed for both (68)Ga-NOTA-c(NGR) and ανβ3 integrin selective (68)Ga-NODAGA-[c(RGD)]2 tracers. APN/CD13 receptor expression of NeDe tumors and metastases was analyzed by western blot. (68)Ga-NOTA-c(NGR) was produced with high specific activity (5.13-5.92GBq/μmol) and with excellent radiochemical purity (95%<), at all cases. Biodistribution studies in normal rats showed that uptake of the (68)Ga-NOTA-c(NGR) was significantly (p⩽0.05) lower in abdominal organs in comparison with (68)Ga-NODAGA-[c(RGD)]2. Both radiotracers were mainly excreted from the kidney. In NeDe tumor bearing rats higher (68)Ga-NOTA-c(NGR) accumulation was found in the tumors than that of the (68)Ga-NODAGA-[c(RGD)]2. Using orthotopic transplantation, metastases were developed which showed specific (68)Ga-NOTA-c(NGR) uptake. Western blot analysis confirmed the presence of APN/CD13 expression in NeDe tumors and metastases. Our novel radiotracer (68)Ga-NOTA-c(NGR) showed specific binding to the APN/CD13 expressed ortho- and heterotopic transplanted NeDe tumors. Therefore, (68)Ga-NOTA-c(NGR) is a suitable tracer for the detection of APN/CD13 positive tumors and metastases in vivo. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Efficiency study of oil cooling of a screw compressor

    SciTech Connect

    Tree, D.R.; McKellar, M.G.

    1989-04-01

    One of the major goals of all compressor manufacturers is to build as efficient a compressor as possible. Over the last several years improvements to the design of screw compressors has made them efficiently competitive with other types of compressors, especially at large loads. The primary purpose of this research is to investigate four different methods of cooling a 250 horsepower compressor and determine their effects on the efficiency of the compressor. Two conventional methods, liquid injection and thermosyphon cooling, and two new methods, V-PLUS and Fresco oil injection, are investigated. The screw compressor used in the tests was a VRS-500 screw compressor made by the Vilter Manufacturing Corporation. 6 figs.

  4. Improved Estrogen Receptor Assessment by PET Using the Novel Radiotracer 4FMFES in ER+ Breast Cancer Patients: an Ongoing Phase II Clinical Trial.

    PubMed

    Paquette, Michel; Lavallée, Éric; Phoenix, Serge; Ouellet, René; Senta, Helena; van Lier, Johan E; Guérin, Brigitte; Lecomte, Roger; Turcotte, Éric E

    2017-08-10

    Following encouraging preclinical and human dosimetry results for the novel estrogen receptor (ER) positron emission tomography (PET) radiotracer 4-fluoro-11β-methoxy-16α-[(18)F]fluoroestradiol (4FMFES), a phase II clinical trial was initiated to compare the PET imaging diagnostic potential of 4FMFES to 16α-[(18)F]fluoroestradiol (FES) in ER positive (ER+) breast cancer patients. Methods: Patients diagnosed with ER+ breast cancer (n = 31) were recruited for this study, including six patients that undertook mastectomy and/or axillary node dissection. For each patient, FES- and 4FMFES-PET/CT scans were done sequentially (within a week) and in random order. One hour following injection of either radiotracer, a head-to-thigh static scan with 2 minutes acquisition per bed position was obtained. Blood samples were taken at different times following injection to assess each tracer metabolism by reverse-phase thin-layer chromatography (TLC). The mean standardized uptake values (SUVMean) of non-specific tissues and the maximum SUV (SUVMax) of the tumor were evaluated for each detected lesion, and tumor-to-non-specific organs ratios were calculated. Results: Blood metabolite analysis 60 minutes after injection of the tracer showed a 2.5-fold increase in metabolic stability of 4FMFES over FES. While for most foci 4FMFES-PET scored similar SUVMax values as compared to FES-PET, tumor contrast improved substantially in all cases. Lower uptake was consistently observed in non-specific tissues for 4FMFES, notably a 4-fold decrease in blood pool activity as compared to FES. Consequently, image quality was considerably improved using 4FMFES, with lower overall background. As a result, 4FMFES successfully identified 9 more lesions than FES. Conclusion: This phase II study with ER+ breast cancer patients shows that 4FMFES-PET achieves lower non-specific signal and better tumor contrast than FES-PET resulting in improved diagnostic confidence and lower false negative diagnoses

  5. Hit efficiency study of CMS prototype forward pixel detectors

    SciTech Connect

    Kim, Dongwook; /Johns Hopkins U.

    2006-01-01

    In this paper the author describes the measurement of the hit efficiency of a prototype pixel device for the CMS forward pixel detector. These pixel detectors were FM type sensors with PSI46V1 chip readout. The data were taken with the 120 GeV proton beam at Fermilab during the period of December 2004 to February 2005. The detectors proved to be highly efficient (99.27 {+-} 0.02%). The inefficiency was primarily located near the corners of the individual pixels.

  6. Efficient Solutions for New Homes Case Study: Savannah Gardens

    SciTech Connect

    2016-03-15

    The Savannah Housing Department is leading sustainable and affordable housing development in Georgia. It partnered with Southface Energy Institute, a member of the U.S. Department of Energy’s Partnership for Home Innovation Building America research team, to seek cost-effective solutions for increasing the energy efficiency of the Savannah Housing Department’s standard single-family home plans in the Savannah Gardens Community. Based on engineering, cost, and constructability analyses, the combined research team chose to pilot two technologies to evaluate efficiency and comfort impacts for homeowners: a heat-pump water heater in an encapsulated attic and an insulated exterior wall sheathing.

  7. Radiosynthesis and evaluation of [11C]-(+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol as a potential radiotracer for in vivo imaging of the dopamine D2 high-affinity state with positron emission tomography.

    PubMed

    Wilson, Alan A; McCormick, Patrick; Kapur, Shitij; Willeit, Matthaeus; Garcia, Armando; Hussey, Doug; Houle, Sylvain; Seeman, Philip; Ginovart, Nathalie

    2005-06-16

    In vivo imaging of dopamine D2 receptors with agonist (as opposed to the more commonly employed antagonist) radiotracers could provide important information on the high-affinity (functional) state of the D2 receptor in illnesses such as schizophrenia, movement disorders, and addictions. We report here the radiosynthesis and evaluation of the potent D2 agonist (+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol, (+)-3, labeled with carbon-11, as a potential radiotracer for imaging the high-affinity state of dopamine D2 receptors with positron emission tomography (PET). [(11)C]-(+)-3 was reliably synthesized in the quantities and at the specific activities and radiochemical purities required for human PET studies. Ex vivo biodistribution studies in rat brain demonstrated that [(11)C]-(+)-3 crossed the blood-brain barrier readily and had an appropriate regional brain distribution for a radiotracer that maps dopamine D2 receptors. The binding of [(11)C]-(+)-3 was saturable and demonstrated an excellent signal-to-noise ratio as measured by its striatum-to-cerebellum ratio of 5.6, 60 min postinjection. The binding was highly stereospecific, and blocking and displacement studies were consistent with selective and specific binding to the dopamine D2 receptors. Further, [(11)C]-(+)-3 showed marked and appropriate sensitivity to both increases and decreases in the levels of endogenous dopamine. Brain radioactive metabolite and physicochemical measurements are in full accord with the desired properties of a neuroreceptor imaging agent for PET. All of the above, coupled with the documented full D2 agonistic properties of (+)-3, strongly indicate that [(11)C]-(+)-3 is a leading candidate radiotracer for the imaging of the dopamine D2 high-affinity state using PET in human subjects.

  8. 3-(Benzyloxy)-1-(5-[(18)F]fluoropentyl)-5-nitro-1H-indazole: a PET radiotracer to measure acetylcholinesterase in brain.

    PubMed

    Fernández, Soledad; Giglio, Javier; Reyes, Ana Laura; Damián, Andrés; Pérez, Concepción; Pérez, Daniel I; González, Mercedes; Oliver, Patricia; Rey, Ana; Engler, Henry; Cerecetto, Hugo

    2017-06-01

    Noninvasive studies of the acetylcholinesterase (AChE) level in Alzheimer's disease (AD) patients can contribute to a better understanding of the disease and its therapeutic. We propose 3-(benzyloxy)-1-(5-[(18)F]fluoropentyl)-5-nitro-1H-indazole, [(18)F]-IND1, structurally related to the AChE-inhibitor CP126,998, as a new positron emission tomography-radiotracer. Radiosynthesis, with 18F, stability, lipophilicity and protein binding of [18F]-IND1 were studied. In vivo behavior, in normal mice and on AD mice models, were also analyzed. [(18)F]-IND1 was obtained in good radiochemical yield, was stable for at least 2 h in different conditions, and had adequate lipophilicity for blood-brain barrier penetration. Biodistribution studies, in normal mice, showed that [(18)F]-IND1 was retained in the brain after 1 h. In vivo tacrine-blocking experiments indicated this uptake could be specifically due to AChE interaction. Studies in transgenic AD mice showed differential, compared with normal mice, binding in many brain regions. [(18)F]-IND1 can be used to detect AChE changes in AD patients.

  9. Basic studies of 3-5 high efficiency cell components

    SciTech Connect

    Lundstrom, M.S.; Melloch, M.R.; Pierret, R.F.; Carpenter, M.S.; Chuang, H.L.; Dodd, P.E.; Keshavarzi, A.; Klausmeier-Brown, M.E.; Lush, G.B.; Stellwag, T.B. )

    1993-01-01

    This project's objective is to improve our understanding of the generation, recombination, and transport of carriers within III-V homo- and heterostructures. The research itself consists of fabricating and characterizing solar cell building blocks'' such as junctions and heterojunctions as well as basic measurements of material parameters. A significant effort is also being directed at characterizing loss mechanisms in high-quality, III-V solar cells fabricated in industrial research laboratories throughout the United States. The project's goal is to use our understanding of the device physics of high-efficiency cell components to maximize cell efficiency. A related goal is the demonstration of new cell structures fabricated by molecular beam epitaxy (MBE). The development of measurement techniques and characterization methodologies is also a project objective. This report describes our progress during the fifth and final year of the project. During the past five years, we've teamed a great deal about heavy doping effects in p[sup +] and n[sup +] GaAs and have explored their implications for solar cells. We have developed an understanding of the dominant recombination losses in present-day, high-efficiency cells. We've learned to appreciated the importance of recombination at the perimeter of the cell and have developed techniques for chemically passivating such edges. Finally, we've demonstrated that films grown by molecular beam epitaxy are suitable for high-efficiency cell research.

  10. Genomewide association study of reproductive efficiency in female cattle

    USDA-ARS?s Scientific Manuscript database

    Reproductive efficiency is of economic importance in commercial beef cattle production, as failure to achieve pregnancy reduces the number of calves marketed per cow exposed. Identification of genetic markers with predictive merit for reproductive success would facilitate early selection of sires w...

  11. Numerical study of particle capture efficiency in fibrous filter

    NASA Astrophysics Data System (ADS)

    Fan, Jianhua; Lominé, Franck; Hellou, Mustapha

    2017-06-01

    Numerical simulations are performed for transport and deposition of particles over a fixed obstacle in a fluid flow. The effect of particle size and Stokes number on the particle capture efficiency is investigated using two methods. The first one is one-way coupling combining Lattice Boltzmann (LB) method with Lagrangian point-like approach. The second one is two-way coupling based on the coupling between Lattice Boltzmann method and discrete element (DE) method, which consider the particle influence on the fluid. Then the single fiber collection efficiency characterized by Stokes number (St) are simulated by LB-DE methods. Results show that two-way coupling method is more appropriate in our case for particles larger than 8 μm. A good agreement has also been observed between our simulation results and existing correlations for single fiber collection efficiency. The numerical simulations presented in this work are useful to understand the particle transport and deposition and to predict the capture efficiency.

  12. Synthesis and characterization of (68)Ga-labeled curcumin and curcuminoid complexes as potential radiotracers for imaging of cancer and Alzheimer's disease.

    PubMed

    Asti, Mattia; Ferrari, Erika; Croci, Stefania; Atti, Giulia; Rubagotti, Sara; Iori, Michele; Capponi, Pier C; Zerbini, Alessandro; Saladini, Monica; Versari, Annibale

    2014-05-19

    Curcumin (CUR) and curcuminoids complexes labeled with fluorine-18 or technetium-99m have recently shown their potential as diagnostic tools for Alzheimer's disease. Gallium-68 is a positron-emitting, generator-produced radionuclide, and its properties can be exploited in situ in medical facilities without a cyclotron. Moreover, CUR showed a higher uptake in tumor cells compared to normal cells, suggesting potential diagnostic applications in this field. In spite of this, no studies using labeled CUR have been performed in this direction, so far. Herein, (68)Ga-labeled complexes with CUR and two curcuminoids, namely diacetyl-curcumin (DAC) and bis(dehydroxy)curcumin (bDHC), were synthesized and characterized by means of experimental and theoretical approaches. Moreover, a first evaluation of their affinity to synthetic β-amyloid fibrils and uptake by A549 lung cancer cells was performed to show the potential application of these new labeled curcuminoids in these diagnostic fields. The radiotracers were prepared by reacting (68)Ga(3+) obtained from a (68)Ge/(68)Ga generator with 1 mg/mL curcuminoids solutions. Reaction parameters (precursor amount, reaction temperature, and pH) were optimized to obtain high and reproducible radiochemical yield and purity. Stoichiometry and formation of the curcuminoid complexes were investigated by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, NMR, ultraviolet-visible, and fluorescence spectroscopy on the equivalent (nat)Ga-curcuminoids (nat = natural) complexes, and their structure was computed by theoretical density functional theory calculations. The analyses evidenced that CUR, DAC, and bDHC were predominantly in the keto-enol form and attested to Ga(L)2(+) species formation. Identity of the (68)Ga(L)2(+) complexes was confirmed by coelution with the equivalent (nat)Ga(L)2(+) complexes in ultrahigh-performance liquid chromatography analyses.(68)Ga(CUR)2(+), (68)Ga(DAC)2(+), and (68)Ga(bDHC)2

  13. Efficiency study of oil cooling of a screw compressor

    SciTech Connect

    Tree, D.R.; McKellar, M.G. . Ray W. Herrick Labs.); Fresco, A. )

    1990-01-01

    One of the major goals of all compressor manufacturers is to design and build as efficient a compressor as possible. In a screw compressor it appears that the way the compressor is cooled can have an effect on the compressor's efficiency. This paper presents experimental data on three different screw compressor cooling methods: Liquid Refrigerant Injection Cooling System; Thermosyphon Cooling System; and Oil Injection System. All tests were conducted on a hot gas bypass system using refrigerant R-22. The data taken shows that the Oil Injection System is slightly better than the other two. These tests should be repeated with a higher oil flow rate and ammonia as the working fluid. 10 figs.

  14. Energy efficient engine preliminary design and integration studies

    NASA Technical Reports Server (NTRS)

    Johnston, R. P.; Hemsworth, M. C.

    1978-01-01

    The characteristics and systems benefits of an energy efficient engine (E3) suitable for use on advanced subsonic transport aircraft were determined. Relative to a current CF6-50C engine, the following benefits were estimated: 14.4% reduction in installed cruise specific fuel consumption, and a reduction in direct operating cost of more than 5%. The advanced technology E3 system would also permit: compliance with FAR 36 (1977) noise limits, and compliance with 1981 EPA emission standards.

  15. Radiotracers in PETT: strategies for in vivo receptor activity, Schizophernia, and Alzheimer's Dementia studies

    SciTech Connect

    Wolf, A.P.

    1984-01-01

    Using /sup 18/F-spiperone, a one compartment system with a driving function as model, blocking agents such as butaclamol and ketanserin, assay of the live adult female baboon striatum over the 8 h period, and assay of the parent compound in plasma, it is apparent that residence times in the living tissue and those estimated from in vitro tritium data are at variance. Occupancy rises to a maximum for /sup 18/F benperidol and /sup 18/F haloperidol after approx. 25 minutes and for /sup 18/F spiperone after approx. 75 minutes, but the striatum concentration of /sup 18/F-spiperone and benperiodol remain nearly constant over an eight hour period whereas /sup 18/F haloperidol concentration starts falling almost immediately to half its maximum value at 8 hrs. The best fit to our current data gives a preliminary off rate constant of 0.0057 min/sup -1/.

  16. In Vivo Distribution of Liposome Encapsulated Hemoglobin Studied with Imaging Radiotracers

    DTIC Science & Technology

    1993-07-29

    looked primarily at the ability of the 99mTc liposomes to detect an acute lesion following balloon angioplasty . A better model yet to be tried is to...the efficacy of cholesterol lowering drugs in the treatment of atherosclerosis. We placed a balloon catheter in the abdominal aorta in Flemish Giant

  17. Isomerism of [64Cu-NOTA-Bn]-labeled radiotracers: separation of two complex isomers and determination of their interconversion energy barrier using ion pair chromatography.

    PubMed

    Schlesinger, Joern; Rajander, Johan; Ihalainen, Janne A; Ramesh, Dinesh; Eklund, Patrik; Fagerholm, Veronica; Nuutila, Pirjo; Solin, Olof

    2011-05-16

    The model complex [(64)Cu((S)-p-NH(2)-Bn-NOTA)](-) ([(64)Cu]1) was used to study the isomerism of [(64)Cu-NOTA-Bn]-labeled radiotracers. Two complex isomers [(64)Cu]1a and [(64)Cu]1b, which were formed at a ratio of 1:9 during the complexation of [(64)Cu]Cu(2+) with (S)-p-NH(2)-Bn-NOTA, were separated using ion pair chromatography. To study the interconversion, the nonradioactive complex isomers Cu1a and Cu1b were separated and thermally treated at 90 °C in both ammonium acetate solution and deionized water. A faster interconversion rate was observed for both isomers with lower concentrations of ammonium ions. At the end of reaction, the thermodynamic Cu1a to Cu1b equilibrium ratio was 6:94. The particular energy barriers of the interconversion for Cu1a and Cu1b were 130 kJ mol(-1) and 140 kJ mol(-1). Spectrophotometric measurements with Cu1a and Cu1b revealed two isomers adopting different geometrical configurations.

  18. Structural efficiency study of graphite-epoxy aircraft rib structures

    NASA Technical Reports Server (NTRS)

    Swanson, Gary D.; Gurdal, Zafer; Starnes, James H., Jr.

    1988-01-01

    Attention is given to the structural efficiencies obtainable with optimally designed graphite/epoxy wing rib panel configurations that are potentially economically manufacturable. Some ribs are commonly used as fuel cell closeout panels, and are accordingly subjected to out-of-plane pressure loads in addition to the in-plane axial compressive and shear loads resulting from the wing loading. The present minimum-weight panel designs satisfy buckling and strength constraints for wing rib panels subjected to a wide range of combined load conditions.

  19. Flow Structures and Efficiency of Swimming Fish school: Numerical Study

    NASA Astrophysics Data System (ADS)

    Yatagai, Yuzuru; Hattori, Yuji

    2013-11-01

    The flow structure and energy-saving mechanism in fish school is numerically investigated by using the volume penalization method. We calculate the various patterns of configuration of fishes and investigate the relation between spatial arrangement and the performance of fish. It is found that the down-stream fish gains a hydrodynamic advantage from the upstream wake shed by the upstream fish. The most efficient configuration is that the downstream fish is placed in the wake. It reduces the drag force of the downstream fish in comparison with that in solo swimming.

  20. Study of LHCD efficiency on the FT-2 tokamak

    SciTech Connect

    Lashkul, S. I.; Altukhov, A. B.; Gurchenko, A. D.; Dyachenko, V. V.; Esipov, L. A.; Kantor, M. Yu.; Kouprienko, D. V.; Irzak, M. A.; Saveliev, A. N.; Sidorov, A. V.; Shatalin, S. V.

    2009-11-26

    The paper pays the main attention to the LHCD efficiency in experiments on the FT-2 tokamak. LH wave spectra P(N{sub z}) excited by the grill computed by GRILL3D code are presented. Physical processes responsible for termination of the CD with density rise are discussed for lower and higher plasma currents that are for relatively cold and relatively hot plasmas. A role of parametric processes and additional impurity influx for CD switching-off in the plasma are considered for those conditions.

  1. Affinity of (nat/68)Ga-Labelled Curcumin and Curcuminoid Complexes for β-Amyloid Plaques: Towards the Development of New Metal-Curcumin Based Radiotracers.

    PubMed

    Rubagotti, Sara; Croci, Stefania; Ferrari, Erika; Iori, Michele; Capponi, Pier C; Lorenzini, Luca; Calzà, Laura; Versari, Annibale; Asti, Mattia

    2016-09-06

    Curcumin derivatives labelled with fluorine-18 or technetium-99m have recently shown their potential as diagnostic tools for Alzheimer's disease. Nevertheless, no study by exploiting the labelling with gallium-68 has been performed so far, in spite of its suitable properties (positron emitter, generator produced radionuclide). Herein, an evaluation of the affinity for synthetic β-amyloid fibrils and for amyloid plaques of three (nat/68)Ga-labelled curcumin analogues, namely curcumin curcumin (CUR), bis-dehydroxy-curcumin (bDHC) and diacetyl-curcumin (DAC), was performed. Affinity and specificity were tested in vitro on amyloid synthetic fibrils by using gallium-68 labelled compounds. Post-mortem brain cryosections from Tg2576 mice were used for the ex vivo visualization of amyloid plaques. The affinity of (68)Ga(CUR)₂⁺, (68)Ga(DAC)₂⁺, and (68)Ga(bDHC)₂⁺ for synthetic β-amyloid fibrils was moderate and their uptake could be observed in vitro. On the other hand, amyloid plaques could not be visualized on brain sections of Tg2576 mice after injection, probably due to the low stability of the complexes in vivo and of a hampered passage through the blood-brain barrier. Like curcumin, all (nat/68)Ga-curcuminoid complexes maintain a high affinity for β-amyloid plaques. However, structural modifications are still needed to improve their applicability as radiotracers in vivo.

  2. Affinity of nat/68Ga-Labelled Curcumin and Curcuminoid Complexes for β-Amyloid Plaques: Towards the Development of New Metal-Curcumin Based Radiotracers

    PubMed Central

    Rubagotti, Sara; Croci, Stefania; Ferrari, Erika; Iori, Michele; Capponi, Pier C.; Lorenzini, Luca; Calzà, Laura; Versari, Annibale; Asti, Mattia

    2016-01-01

    Curcumin derivatives labelled with fluorine-18 or technetium-99m have recently shown their potential as diagnostic tools for Alzheimer’s disease. Nevertheless, no study by exploiting the labelling with gallium-68 has been performed so far, in spite of its suitable properties (positron emitter, generator produced radionuclide). Herein, an evaluation of the affinity for synthetic β-amyloid fibrils and for amyloid plaques of three nat/68Ga-labelled curcumin analogues, namely curcumin curcumin (CUR), bis-dehydroxy-curcumin (bDHC) and diacetyl-curcumin (DAC), was performed. Affinity and specificity were tested in vitro on amyloid synthetic fibrils by using gallium-68 labelled compounds. Post-mortem brain cryosections from Tg2576 mice were used for the ex vivo visualization of amyloid plaques. The affinity of 68Ga(CUR)2+, 68Ga(DAC)2+, and 68Ga(bDHC)2+ for synthetic β-amyloid fibrils was moderate and their uptake could be observed in vitro. On the other hand, amyloid plaques could not be visualized on brain sections of Tg2576 mice after injection, probably due to the low stability of the complexes in vivo and of a hampered passage through the blood–brain barrier. Like curcumin, all nat/68Ga-curcuminoid complexes maintain a high affinity for β-amyloid plaques. However, structural modifications are still needed to improve their applicability as radiotracers in vivo. PMID:27608011

  3. [Studies on the efficient syntheses of the drug metabolites].

    PubMed

    Otsubo, K

    2000-11-01

    This review summarizes our recent findings in the syntheses of drug metabolites. The metabolites of Grepafloxacin (1) and OPC-14117 (10) were prepared from the common intermediates (5) and (21), respectively. Moreover, treatment of 10 with a model P450 system led to a benzyl alcohol derivative (11) in one step. OPC-31260 (22) was efficiently N-dealkylated using several metalloporphyrins with oxidants to afford three metabolites (23-25). In addition, I succeeded in obtaining the metabolite (23) in high yield from N-oxide (26) not only as an oxygen donor but also as a substrate, there after, in the model P450 system. Optically active metabolites of OPC-29030 (27) were prepared by enzyme-catalyzed enantioselective transesterification of racemic sulfinyl metabolites. On the other hand, a chiral 1,1'-bi-2-naphthol derivative (38a) was found to be an efficient asymmetric acylating agent for a secondary alcohol (36) which is a valuable intermediate for preparing optically active metabolites of 22. Furthermore, metabolites (45) and (47) of OPC-21268 (44) were prepared using SmI2-induced cyclization and oxidative decarboxylation with Pb(OAc)4 as key steps, respectively.

  4. Study on High Efficient Electric Vehicle Wireless Charging System

    NASA Astrophysics Data System (ADS)

    Chen, H. X.; Liu, Z. Z.; Zeng, H.; Qu, X. D.; Hou, Y. J.

    2016-08-01

    Electric and unmanned is a new trend in the development of automobile, cable charging pile can not meet the demand of unmanned electric vehicle. Wireless charging system for electric vehicle has a high level of automation, which can be realized by unmanned operation, and the wireless charging technology has been paid more and more attention. This paper first analyses the differences in S-S (series-series) and S-P (series-parallel) type resonant wireless power supply system, combined with the load characteristics of electric vehicle, S-S type resonant structure was used in this system. This paper analyses the coupling coefficient of several common coil structure changes with the moving distance of Maxwell Ansys software, the performance of disc type coil structure is better. Then the simulation model is established by Simulink toolbox in Matlab, to analyse the power and efficiency characteristics of the whole system. Finally, the experiment platform is set up to verify the feasibility of the whole system and optimize the system. Based on the theoretical and simulation analysis, the higher charging efficiency is obtained by optimizing the magnetic coupling mechanism.

  5. Study on Efficiency Improvement of Hermetic Rotary Compressors

    NASA Astrophysics Data System (ADS)

    Matsushima, Masatoshi; Nomura, Tomohiro; Nishimura, Nobuya; Iyota, Hiroyuki; Inaba, Koichi

    This research was conducted in order to better identify the torque loss of a hermetic rotary compressor for one revolution, and to directly obtain the actual shaft power of the compressor. A testing compressor and a gas cycle type simplified calorimeter were developed for direct measurement of the compressor torque. A strain gauge was stuck on the shaft between a compressor and a motor. Thus, the compressor torque could be measured directly by the strain gauge and data were transmitted to out of the compressor's vessel through a slip ring. Rotational speed of the compressor was measured by using a gap sensor also. From these measurement results, actual shaft power was calculated experimentally. On the other hand, effective compressive torque for compressing refrigerant gas was predicted theoretically. From both experimental and theoretical results, torque loss of the compressor was determined as the difference of the compressor torque from the effective compressive torque. Consequently, a loss of over-compression could be revealed from the torque loss experimentally. Furthermore, overall adiabatic efficiencies of compressors obtained by the actual shaft power were 1.1∼3.5% higher than former overall adiabatic efficiencies obtained by the motor output.

  6. Structural efficiency study of composite wing rib structures

    NASA Technical Reports Server (NTRS)

    Swanson, Gary D.; Gurdal, Zafer; Starnes, James H., Jr.

    1988-01-01

    A series of short stiffened panel designs which may be applied to a preliminary design assessment of an aircraft wing rib is presented. The computer program PASCO is used as the primary design and analysis tool to assess the structural efficiency and geometry of a tailored corrugated panel, a corrugated panel with a continuous laminate, a hat stiffened panel, a blade stiffened panel, and an unstiffened flat plate. To correct some of the shortcomings in the PASCO analysis when shear is present, a two step iterative process using the computer program VICON is used. The loadings considered include combinations of axial compression, shear, and lateral pressure. The loading ranges considered are broad enough such that the designs presented may be applied to other stiffened panel applications. An assessment is made of laminate variations, increased spacing, and nonoptimum geometric variations, including a beaded panel, on the design of the panels.

  7. Enhancing health programme efficiency: a Cambodian case study.

    PubMed

    Stuer, F

    1998-09-01

    In 1995, the Cambodian Urban Health Care Association (CUHCA) was set up as facilitator between private health care providers and patients, guaranteeing good quality health care and fair pricing to patients and providing training and logistic support to providers. Providers were engaged on a fee-for-service basis and competition encouraged. CUHCA's objectives followed the same line of thought as the 1993 World Development Report, aiming at influencing the unregulated private health care market through competition mechanisms. But soon after the start of the project the basic problem was recognized to be not the absence of effective government regulation but rather that consumers lack the requisite knowledge to make good choices in the market for health services. CUHCA had not adequately addressed the demand for health services. The original supply-side strategy of improving health services by increasing competition was a failure. In order to improve CUHCA's health programme efficiency the association's objectives were subsequently redefined and its functioning reorganized. CUHCA now tries to educate consumers and provides good quality services so that consumers will be able to act on the basis of their newly acquired knowledge. CUHCA's health centres serve as model clinics for first-line health care. Community educators organize information, education and communication (IEC) activities. Staff help school teachers to improve formal health education in schools and CUHCA assists local leaders in sanitation development. Only full-time personnel are employed, encouraging team spirit and communication with the target population. Salaries are based on team performance. The CUHCA programme demonstrates that, depending on the market situation, health programme models need to address both the supply and the demand for services in order to be efficient. Where consumers lack essential knowledge to make appropriate choices in the health service market, interventions should focus

  8. Spin Contrast Variation Study of Fuel-efficient Tire Rubber

    NASA Astrophysics Data System (ADS)

    Noda, Yohei; Yamaguchi, Daisuke; Hashimoto, Takeji; Shamoto, Shin-ichi; Koizumi, Satoshi; Yuasa, Takeshi; Tominaga, Tetsuo; Sone, Takuo

    The scattering length of a proton against a polarized neutron depends strongly on the polarization of proton spins (PH). This dependence can be utilized for contrast variation in small angle neutron scattering (SANS). We applied this spin contrast variation technique to a silica-filled SBR rubber specimen, which is widely used for tread rubber of fuel-efficient tires. For realizing high PH, we used dynamic nuclear polarization (DNP) technique, in which large polarization of electron spin at low temperature and high magnetic field is transferred to proton spin by microwave irradiation with a tuned frequency. As this electron spin source, we doped stable radical TEMPO (2,2,6,6-tetramethyl piperidine 1-oxyl) into the rubber sample by use of a vapor sorption technique. For the TEMPO-doped rubber sample, SANS measurements were conducted at PH = -20%, 0%, and +13%, with almost fully polarized neutron beam %) with its wavelength of 6.5±0.6 Å. The SANS profile clearly changed as a function of PH, which can be explained by the PH dependence of the neutron scattering length densities of the main three components (SBR, silica and zinc oxide). By a linear transformation of the profiles obtained at the three different PH values, we successfully determined the partial scattering function of silica, which reflects the aggregation of silica particles.

  9. High efficient ZnO nanowalnuts photocatalyst: A case study

    SciTech Connect

    Yan, Feng; Zhang, Siwen; Liu, Yang; Liu, Hongfeng; Qu, Fengyu; Cai, Xue; Wu, Xiang

    2014-11-15

    Highlights: • Walnut-like ZnO nanostructures are synthesized through a facile hydrothermal method. • Morphologies and microstructures of the as-obtained ZnO products were investigated. • The photocatalytic results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. - Abstract: Walnut-like ZnO nanostructures are successfully synthesized through a facile hydrothermal method. The structure and morphology of the as-synthesized products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic properties of ZnO nanowalnuts are investigated by photodegradating several organic dyes, such as Congo red (CR), methyl orange (MO) and eosin red aqueous solutions under UV irradiation, respectively. The results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. In addition, eosin red and Congo red (CR) aqueous solution degradation experiments are also conducted in the same condition, respectively. It showed that ZnO nanowalnuts represent high photocatalytic activities with a degradation efficiency of 87% for CR with 115 min of irradiation and 97% for eosin red with 55 min of irradiation. The reported ZnO products may be promising candidates as the photocatalysts in waste water treatment.

  10. Hazardous waste cleanup: A case study for developing efficient programs

    SciTech Connect

    Elcock, D.; Puder, M.G.

    1995-06-01

    As officials in Pacific Basin Countries develop laws and policies for cleaning up hazardous wastes, experiences of countries with such instruments in place may be instructive. The United States has addressed cleanups of abandoned hazardous waste sites through the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The US Congress enacted CERCLA in 1980. The task of cleaning up waste sites became larger and more costly than originally envisioned and as a result, Congress strengthened and expanded CERCLA in 1986. Today, many industry representatives, environmentalists, and other interested parties say the program is still costly and ineffective, and Congress is responding through a reauthorization process to change the law once again. Because the law and modifications to it can affect company operations and revenues, industries want to know the potential consequences of such changes. Argonne National Laboratory (ANL) recently developed a baseline for one economic sector -- the US energy industry -- against which impacts of proposed changes to CERCLA could be measured. Difficulties encountered in locating and interpreting the data for developing that baseline suggest that legislation should not only provide for meeting its stated goals (e.g., protection of human health and the environment) but also allow for its efficient evaluation over time. This lesson can be applied to any nation contemplating hazardous waste cleanup laws and policies.

  11. Energy efficiency study of single-wide manufactured homes

    SciTech Connect

    Yarbrough, D.W.; Andrews, G.J.; Stovall, T.K.; Kelly, T.

    1999-12-01

    This Cooperative Research and Development Agreement (CRADA) was among Tennessee Technological University, Clayton Homes, Inc., and Oak Ridge National Laboratory (ORNL). Manufactured homes now make up a substantial portion of the new home market, and improving the energy efficiency of these homes would save significant amounts of energy. This project explored the impact of differing levels of attic insulation, the use of evacuated insulation panels, and the application of a solar reflective roof coating. The performance of the installed roof cavity insulation compared favorably with that predicted by laboratory measurements. The more heavily insulated of the two units used about 30% less energy over the period of the project than the standard unit. Based on the experimental data, computer simulations for nine cities were completed for a single-wide manufactured home with the solar reflective roof coating. Annual electric power savings ranged from 894 kWh in Rapid City to 2119 kWh for the same roof area in Los Angeles. The field performance of vacuum insulation panels was compared with laboratory performance. The panels will perform as expected if protected from puncture.

  12. Case study: improving efficiency in a large hospital laboratory.

    PubMed

    Bartel, Marilynn

    2004-01-01

    Saint Francis Health System (SFHS) consists of three hospitals and one clinic: Saint Francis Hospital (SFH); Broken Arrow Medical Center; Laureate Psychiatric Hospital; and Warren Clinic. SFHS has 670 physicians on staff and serves medical (oncology, orthopedic, neurology, and renal), surgical, cardiac, women and infant, pediatric, transplant, and trauma patients in Tulsa County, Oklahoma, which has a population of 660,000. SFH incorporates 706 staffed beds, including 126 pediatric beds and 119 critical care beds. Each year, the health system averages 38,000 admissions, 70,000 emergency department visits, 25,000 surgeries, and 3,500 births. Saint Francis Laboratory is located within the main hospital facility (SFH) and functions as a core lab for the health system. The lab also coordinates lab services with Saint Francis Heart Hospital, a physician-system joint venture. The Optimal Equipment Configuration (OEC) Project was designed by the Clinical Laboratory Services division of Premier, a group purchasing organization, with the goal of determining whether laboratories could improve efficiency and decrease unit cost by using a single-source vendor. Participants included seven business partners (Abbott, Bayer, Beckman/Coulter, Dade/Behring, J&J/ Ortho, Olympus, and Roche) and 21 laboratory sites (a small, mid-sized, and large site for each vendor). SFH laboratory staff embraced Premier's concept and viewed the OEC project as an opportunity to "energize" laboratory operations. SFH partnered with Abbott, their primary equipment vendor, for the project. Using resources and tools made available through the project, the laboratory was re-engineered to simplify workflow, increase productivity, and decrease costs by adding automation and changing to centralized specimen processing. Abbott and SFH shared a common vision for the project and enhanced their partnership through increased communication and problem solving. Abbott's area representatives provided for third

  13. Application of Palladium-Mediated 18F-Fluorination to PET Radiotracer Development: Overcoming Hurdles to Translation

    PubMed Central

    Kamlet, Adam S.; Neumann, Constanze N.; Lee, Eunsung; Carlin, Stephen M.; Moseley, Christian K.; Stephenson, Nickeisha; Hooker, Jacob M.; Ritter, Tobias

    2013-01-01

    New chemistry methods for the synthesis of radiolabeled small molecules have the potential to impact clinical positron emission tomography (PET) imaging, if they can be successfully translated. However, progression of modern reactions from the stage of synthetic chemistry development to the preparation of radiotracer doses ready for use in human PET imaging is challenging and rare. Here we describe the process of and the successful translation of a modern palladium-mediated fluorination reaction to non-human primate (NHP) baboon PET imaging–an important milestone on the path to human PET imaging. The method, which transforms [18F]fluoride into an electrophilic fluorination reagent, provides access to aryl–18F bonds that would be challenging to synthesize via conventional radiochemistry methods. PMID:23554994

  14. Application of palladium-mediated (18)F-fluorination to PET radiotracer development: overcoming hurdles to translation.

    PubMed

    Kamlet, Adam S; Neumann, Constanze N; Lee, Eunsung; Carlin, Stephen M; Moseley, Christian K; Stephenson, Nickeisha; Hooker, Jacob M; Ritter, Tobias

    2013-01-01

    New chemistry methods for the synthesis of radiolabeled small molecules have the potential to impact clinical positron emission tomography (PET) imaging, if they can be successfully translated. However, progression of modern reactions from the stage of synthetic chemistry development to the preparation of radiotracer doses ready for use in human PET imaging is challenging and rare. Here we describe the process of and the successful translation of a modern palladium-mediated fluorination reaction to non-human primate (NHP) baboon PET imaging-an important milestone on the path to human PET imaging. The method, which transforms [(18)F]fluoride into an electrophilic fluorination reagent, provides access to aryl-(18)F bonds that would be challenging to synthesize via conventional radiochemistry methods.

  15. The role of electromagnetic separators in the production of radiotracers for bio-medical research and nuclear medical application

    NASA Astrophysics Data System (ADS)

    Beyer, Gerd J.; Ruth, Thomas J.

    2003-05-01

    With the growing complexity of positron emission tomography/single photon emission computed tomography imaging and the new developments in systemic radionuclide therapy there is a growing need for radioisotope preparations with higher radiochemical and radionuclidic purity that has not been achievable before. Especially important for the new applications is the specific activity of the radiotracer. Conventional methods in medical isotope production have reached their technical limitations. The role of isotope separators is discussed with examples of typical production and characterization experiments conducted at the ISOLDE and TRIUMF facilities. These preliminary experiments indicate that isotope separators have a definite role to play in the future for the production of radioisotopes for biomedical research and medical application.

  16. Ionization efficiency studies for xenon ions with thesuperconducting ECR ion source VENUS

    SciTech Connect

    Leitner, Daniela; Lyneis, Claude M.; Todd, DamonS.; Tarvainen,Olli

    2007-06-05

    Ionization efficiency studies for high charge state xenon ions using a calibrated gas leak are presented. A 75% enriched {sup 129}Xe gas leak with a gas flow equivalent to 5.11p{mu}A was used in all the measurements. The experiments were performed at the VENUS (Versatile ECR ion source for Nuclear Science) ion source for 18 GHz, 28 GHz and double frequency operation. Overall, total ionization efficiencies close to 100% and ionization efficiencies into a single charge state up to 22% were measured. The influence of the biased disk on the ionization efficiency was studied and the results were somewhat surprising. When the biased disk was removed from the plasma chamber, the ionization efficiency was dramatically reduced for single frequency operation. However, using double frequency heating the ionization efficiencies achieved without the biased disk almost matched the ionization efficiencies achieved with the biased probe. In addition, we have studied the influence of the support gas on the charge state distribution of the xenon ions. Either pure oxygen or a mixture of oxygen and helium were used as support gases. The addition of a small amount of helium can increase the ionization efficiency into a single charge state by narrowing the charge state distribution. Furthermore by varying the helium flow the most efficient charge state can be shifted over a wide range without compromising the ionization efficiency. This is not possible using only oxygen as support gas. Results from these studies are presented and discussed.

  17. Job satisfaction or production? How staff and leadership understand operating room efficiency: a qualitative study.

    PubMed

    Arakelian, E; Gunningberg, L; Larsson, J

    2008-11-01

    How to increase efficiency in operating departments has been widely studied. However, there is no overall definition of efficiency. Supervisors urging staff to work efficiently may meet strong reactions due to staff believing that demands for efficiency means just stress at work. Differences in how efficiency is understood may constitute an obstacle to supervisors' efforts to promote it. This study aimed to explore how staff and leadership understand operating room efficiency. Twenty-one members of staff and supervisors in an operating department in a Swedish county hospital were interviewed. The analysis was performed with a phenomenographic approach that aims to discover the variations in how a phenomenon is understood by a group of people. Six categories were found in the understanding of operation room efficiency: (A) having the right qualifications; (B) enjoying work; (C) planning and having good control and overview; (D) each professional performing the correct tasks; (E) completing a work assignment; and (F) producing as much as possible per time unit. The most significant finding was that most of the nurses and assistant nurses understood efficiency as individual knowledge and experience emphasizing the importance of the work process, whereas the supervisors and physicians understood efficiency in terms of production per time unit or completing an assignment. The concept 'operating room efficiency' is understood in different ways by leadership and staff members. Supervisors who are aware of this variation will have better prerequisites for defining the concept and for creating a common platform towards becoming efficient.

  18. Synthesis and Evaluation of New Generation Cross-Bridged Bifunctional Chelator for (64)Cu Radiotracers.

    PubMed

    Dale, Ajit V; An, Gwang Il; Pandya, Darpan N; Ha, Yeong Su; Bhatt, Nikunj; Soni, Nisarg; Lee, Hochun; Ahn, Heesu; Sarkar, Swarbhanu; Lee, Woonghee; Huynh, Phuong Tu; Kim, Jung Young; Gwon, Mi-Ri; Kim, Sung Hong; Park, Jae Gyu; Yoon, Young-Ran; Yoo, Jeongsoo

    2015-09-08

    Bifunctional chelators have been successfully used to construct (64)Cu-labeled radiopharmaceuticals. Previously reported chelators with cross-bridged cyclam backbones have various essential features such as high stability of the copper(II) complex, high efficiency of radiolabeling at room temperature, and good biological inertness of the radiolabeled complex, along with rapid body clearance. Here, we report a new generation propylene-cross-bridged chelator with hybrid acetate/phosphonate pendant groups (PCB-TE1A1P) developed with the aim of combining these key properties in a single chelator. The PCB-TE1A1P was synthesized from cyclam with good overall yield. The Cu(II) complex of our chelator showed good robustness in kinetic stability evaluation experiments, such as acidic decomplexation and cyclic voltammetry studies. The Cu(II) complex of PCB-TE1A1P remained intact under highly acidic conditions (12 M HCl, 90 °C) for 8 d and showed quasi-reversible reduction/oxidation peaks at -0.77 V in electrochemical studies. PCB-TE1A1P was successfully radiolabeled with (64)Cu ions in an acetate buffer at 60 °C within 60 min. The electrophoresis study revealed that the (64)Cu-PCB-TE1A1P complex has net negative charge in aqueous solution. The biodistribution and in vivo stability study profiles of (64)Cu-PCB-TE1A1P indicated that the radioactive complex was stable under physiological conditions and cleared rapidly from the body. A whole body positron emission tomography (PET) imaging study further confirmed high in vivo stability and fast clearance of the complex in mouse models. In conclusion, PCB-TE1A1P has good potential as a bifunctional chelator for (64)Cu-based radiopharmaceuticals, especially those involving peptides.

  19. Study of efficient video compression algorithms for space shuttle applications

    NASA Technical Reports Server (NTRS)

    Poo, Z.

    1975-01-01

    Results are presented of a study on video data compression techniques applicable to space flight communication. This study is directed towards monochrome (black and white) picture communication with special emphasis on feasibility of hardware implementation. The primary factors for such a communication system in space flight application are: picture quality, system reliability, power comsumption, and hardware weight. In terms of hardware implementation, these are directly related to hardware complexity, effectiveness of the hardware algorithm, immunity of the source code to channel noise, and data transmission rate (or transmission bandwidth). A system is recommended, and its hardware requirement summarized. Simulations of the study were performed on the improved LIM video controller which is computer-controlled by the META-4 CPU.

  20. Integrated energy management study. Energy efficient transport program

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The Integrated Energy Management (IEM) Study investigated the practicality and feasibility of a closed-loop energy management system for transport aircraft. The study involved: (1) instrumentation and collection of in-flight data for a United Airlines 727-200 flying 80 revenue flights throughout the United Airlines network,(2) analysis of the in-flight data to select representative city pairs and establish operational procedures employed in flying a reference flight profile, (3) simulation of the reference profile in a fast-time model to verify the model and establish performance values against which to measure IEM benefits, (4) development of IEM algorithms, and (5) assessment of the IEM concept.

  1. A pilot study of energy efficient air cleaning for ozone

    SciTech Connect

    Gundel, Lara A.; Sullivan, Douglas P.; Katsapov, Gregory Y.; Fisk, William J.

    2002-11-01

    A laboratory pilot study has been undertaken with the material that showed the most promise (high capacity and low pressure drop) based on the literature review and associated calculations. The best-performing air cleaner was a commercially available pleated filter that contained a thin layer of small activated carbon particles between two sheets of non-woven fibrous webbing. We will refer to this unit as the ''ozone filter'' although it is marketed for removal of volatile organic compounds (VOCs) from automobile passenger compartments. This pilot study strongly suggests that ozone air cleaning can be practical in commercial air handling systems; however, further tests are needed to assess air cleaner performance under a wider range of conditions.

  2. A comparative study on the arc and melting efficiencies of arc welding processes

    SciTech Connect

    DuPont, J.N.; Marder, A.R.

    1996-12-31

    A study was conducted on the arc and melting efficiency of the plasma arc, gas tungsten arc, gas metal arc, and submerged arc welding processes. Arc efficiency was determined as a function of current for each process using A36 steel base metal. Melting efficiency was evaluated with variations in arc power and travel speed during deposition of austenitic stainless steel filler wire onto A36 steel substrates. The arc efficiency did not vary significantly within a given process over the range of currents investigated. The consumable electrode processes exhibited the highest arc efficiency (0.84), followed by the gas tungsten arc (0.67) and plasma arc (0.47) processes. A semi-empirical relation was developed for the melting efficiency as a function of net arc power and travel speed which described the experimental data reasonably well. An interaction was observed between the arc and melting efficiency. A low arc efficiency factor limits the power delivered to the substrate which, in turn, limits the maximum travel speed for a given set of conditions. High melting efficiency is favored by high arc powers and travel speeds. As a result, a low arc efficiency can limit the maximum obtainable melting efficiency.

  3. Energy efficient engine: Preliminary design and integration studies

    NASA Technical Reports Server (NTRS)

    Gray, D. E.

    1978-01-01

    A mixed exhaust, direct drive fan turbofan configuration was selected from four candidates. This choice was based on its ability to exceed study goals of 12% lower thrust specific fuel consumption and 5% lower direct operating cost by the 1990's with commercially acceptable technical risk and relative mechanical simplicity. The evaluation leading to configuration selection is discussed. Necessary technology advancements are identified and related to the goals.

  4. A method to predict the ratio of the tracer conversion rate to the tracer back-diffusion rate of an irreversible-type radiotracer in humans by preclinical evaluations.

    PubMed

    Ohya, Tomoyuki; Zhang, Ming-Rong; Fukumura, Toshimitsu; Fukushi, Kiyoshi; Kikuchi, Tatsuya; Irie, Toshiaki

    2012-10-01

    The aim of this study was to develop a method to predict a tracer's α-value in the human brain on the basis of animal data. The α-value is the ratio of the conversion rate and the back-diffusion rate (k3/k2) and is one of the critical kinetic features of the detection sensitivity of target molecule activity, such as enzyme activity, in the measurement of PET and single-photon emission computed tomography using an irreversible-type radiotracer. The α-value in the rat brain was estimated by a simultaneous assay of the tracer uptake and the target biochemical activity using N-[C]-methylpiperidin-4-yl acetate ([C]MP4A) and N-[C]-methylpiperidin-4-yl propionate ([C]MP4P) as test tracers, both of which are metabolic trapping tracers for measurement of brain acetylcholinesterase. The α-value in humans was then extrapolated from the α-value in rats by considering the differences between the species. The predicted human α-values were compared with those obtained from the kinetic analyses of human PET studies using [C]MP4A and [C]MP4P. The α-values in the human brain cortex were predicted to be 0.51±0.1 for MP4A and 0.25±0.05 for MP4P. These results were close to values reported in other PET studies: 0.48±0.1 to 0.73±0.2 for MP4A and 0.15±0.04 to 0.18±0.04 for MP4P. The α-value predicted by this method would be used for practical selection or development of irreversible-type radiotracers for human use.

  5. Molar efficiency study of chlorinated NPG substitutes in dentin bonding.

    PubMed

    Miniotis, N J; Bennett, P S; Johnston, A D

    1993-06-01

    This study evaluated and compared the contributions to dentin adhesive bonding of three N-phenylglycine analogues with electron-withdrawing substituents on the aromatic ring. These electron-deficient "N-compounds" included: N-(4-chlorophenyl)-glycine (NCPG), N-methyl-N-(4-chlorophenyl)-glycine (NMNCPG), and N-(3,4-dichlorophenyl)-glycine (NDCPG). An experimental three-step dentin-bonding protocol that consisted of sequential application of acidic ferric oxalate solution, an N-compound in acetone, and a surface-active comonomer in acetone was used. The first and third steps were held constant throughout the study. Each N-compound (NCPG, NMNCPG, NDCPG) was used in step two at ten concentrations ranging from 0.0 mol/L (pure acetone) to 5 x 10(-1) mol/L, depending on solubility. After overnight storage in distilled water, the dentin-to-composite bonds were broken in tension. The data were analyzed with ANOVA, and multiple comparisons were performed with Duncan's Multiple Range test. All statistical tests were controlled at alpha = 0.05. At 5 x 10(-3) mol/L, the relative effectiveness of the three N-compounds (as measured by tensile bond strengths) was NMNCPG > NCPG > NDCPG. Of all concentrations studied, the mean bond strengths produced with NMNCPG were statistically as good as or better than those produced by the other two compounds, and NCPG was always as good as or better than NDCPG. Increased electron-withdrawing from the nitrogen of the amine group by the substituents narrowed the effective concentration range for dentin bonding and, in general, produced lower mean bond strengths between dentin and composite.

  6. Optimal design study of high efficiency indium phosphide space solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Flood, Dennis J.

    1990-01-01

    Recently indium phosphide solar cells have achieved beginning of life AMO efficiencies in excess of 19 pct. at 25 C. The high efficiency prospects along with superb radiation tolerance make indium phosphide a leading material for space power requirements. To achieve cost effectiveness, practical cell efficiencies have to be raised to near theoretical limits and thin film indium phosphide cells need to be developed. The optimal design study is described of high efficiency indium phosphide solar cells for space power applications using the PC-1D computer program. It is shown that cells with efficiencies over 22 pct. AMO at 25 C could be fabricated by achieving proper material and process parameters. It is observed that further improvements in cell material and process parameters could lead to experimental cell efficiencies near theoretical limits. The effect of various emitter and base parameters on cell performance was studied.

  7. Energy Efficient Engine program advanced turbofan nacelle definition study

    NASA Technical Reports Server (NTRS)

    Howe, David C.; Wynosky, T. A.

    1985-01-01

    Advanced, low drag, nacelle configurations were defined for some of the more promising propulsion systems identified in the earlier Benefit/Cost Study, to assess the benefits associated with these advanced technology nacelles and formulate programs for developing these nacelles and low volume thrust reversers/spoilers to a state of technology readiness in the early 1990's. The study results established the design feasibility of advanced technology, slim line nacelles applicable to advanced technology, high bypass ratio turbofan engines. Design feasibility was also established for two low volume thrust reverse/spoiler concepts that meet or exceed the required effectiveness for these engines. These nacelle and thrust reverse/spoiler designs were shown to be applicable in engines with takeoff thrust sizes ranging from 24,000 to 60,000 pounds. The reduced weight, drag, and cost of the advanced technology nacelle installations relative to current technology nacelles offer a mission fuel burn savings ranging from 3.0 to 4.5 percent and direct operating cost plus interest improvements from 1.6 to 2.2 percent.

  8. An efficient empirical Bayes method for genomewide association studies.

    PubMed

    Wang, Q; Wei, J; Pan, Y; Xu, S

    2016-08-01

    Linear mixed model (LMM) is one of the most popular methods for genomewide association studies (GWAS). Numerous forms of LMM have been developed; however, there are two major issues in GWAS that have not been fully addressed before. The two issues are (i) the genomic background noise and (ii) low statistical power after Bonferroni correction. We proposed an empirical Bayes (EB) method by assigning each marker effect a normal prior distribution, resulting in shrinkage estimates of marker effects. We found that such a shrinkage approach can selectively shrink marker effects and reduce the noise level to zero for majority of non-associated markers. In the meantime, the EB method allows us to use an 'effective number of tests' to perform Bonferroni correction for multiple tests. Simulation studies for both human and pig data showed that EB method can significantly increase statistical power compared with the widely used exact GWAS methods, such as GEMMA and FaST-LMM-Select. Real data analyses in human breast cancer identified improved detection signals for markers previously known to be associated with breast cancer. We therefore believe that EB method is a valuable tool for identifying the genetic basis of complex traits.

  9. Synthesis and evaluation of [11C]PyrATP-1, a novel radiotracer for PET imaging of glycogen synthase kinase-3β (GSK-3β)

    PubMed Central

    Cole, Erin L.; Shao, Xia; Sherman, Phillip; Quesada, Carole; Fawaz, Maria V.; Desmond, Timothy J.; Scott, Peter J. H.

    2014-01-01

    Introduction The dysfunction of glycogen synthase kinase-3β(GSK-3β) has been implicated in a number of diseases, including Alzheimer’s disease. The ability to non-invasively quantify GSK-3βactivity in vivo is therefore of critical importance, and this work is focused upon development of inhibitors of GSK-3βradiolabeled with carbon-11 to examine quantification of the enzyme using positron emission tomography (PET) imaging. Methods [11C]PyrATP-1 was prepared from the corresponding desmethyl-piperazine precursor in an automated synthesis module. In vivo rodent and primate imaging studies were conducted on a Concorde MicroPET P4 scanner to evaluate imaging properties, and in vitro autoradiography studies with rat brain samples were carried out to examine specific binding. Results 2035 ± 518 MBq (55 ± 14 mCi) of [11C]PyrATP-1 were obtained (1–2% noncorrected radiochemical yield at end-of-synthesis based upon [11C]CO2) with high chemical (>95%) and radiochemical (>99%) purities, and good specific activities (143 ± 52 GBq/µmol (3874 ± 1424 Ci/mmol)), n = 5. In vivo microPET imaging studies revealed poor brain uptake in rodents and non-human primates. Pretreatment of rodents with cyclosporin A resulted in moderately increased brain uptake suggesting Pgp transporter involvement. Autoradiography demonstrated high levels of specific binding in areas of the rodent brain known to be rich in GSK-3β. Conclusion [11C]PyrATP-1 is readily synthesized using standard carbon-11 radiochemistry. However, the poor brain uptake in rodents and non-human primates indicates that the radiotracer is not suitable for the purposes of quantifying GSK-3βin neurological and psychiatric disorders. PMID:24768148

  10. Reinvestigation of the Synthesis and Evaluation of [N-methyl-11C]Vorozole, a Radiotracer Targeting Cytochrome P450 Aromatase

    PubMed Central

    Kim, Sung Won; Biegon, Anat; Katsamanis, Zachary E.; Ehrlich, Carolin W.; Hooker, Jacob M.; Shea, Colleen; Muench, Lisa; Xu, Youwen; King, Payton; Carter, Pauline; Alexoff, David L.; Fowler, Joanna S.

    2009-01-01

    Introduction We reinvestigated the synthesis of [N-methyl-11C]vorozole, a radiotracer for aromatase, and discovered the presence of an N-methyl isomer which was not removed in the original purification method. Herein we report the preparation and PET studies of pure [N-methyl-11C]vorozole. Methods Norvorozole was alkylated with [11C]methyl iodide as previously described and also with unlabeled methyl iodide. A HPLC method was developed to separate the regioisomers. NMR spectroscopy (13C and 2D-NOESY NMR) was used to identify and assign structures to the N-methylated products. Pure [N-methyl-11C]vorozole and the contaminating isomer were compared by PET imaging in the baboon. Results Methylation of norvorozole resulted in a mixture of isomers (1:1:1 ratio) based on new HPLC analysis using a pentafluorophenylpropyl (PFPP) bonded silica column, in which vorozole co-eluted one of its isomers under the original HPLC conditions. Baseline separation of the three labeled isomers was achieved. The N-3 isomer was the contaminant of vorozole, thus correcting the original assignment of isomers. PET studies of pure [N-methyl-11C]vorozole with and without the contaminating N-3 isomer revealed that only [N-methyl-11C]vorozole binds to aromatase. [N-methyl-11C]Vorozole accumulated in all brain regions with highest accumulation in the aromatase-rich amygdala and preoptic area. Accumulation was blocked with vorozole and letrozole consistent with reports of some level of aromatase in many brain regions. Conclusions The discovery of a contaminating labeled isomer and the development of a method for isolating pure [N-methyl-11C]vorozole combine to provide a new scientific tool for PET studies of the biology of aromatase and for drug research and development. PMID:19324278

  11. Study of parallel efficiency in message passing environments

    SciTech Connect

    Hanebutte, U.R.; Tatsumi, Masahiro

    1996-03-01

    A benchmark test using the Message Passing Interface (MPI, an emerging standard for writing message passing programs) has been developed, to study parallel performance in message passing environments. The test is comprised of a computational task of independent calculations followed by a round-robin data communication step. Performance data as a function of computational granularity and message passing requirements are presented for the IBM SPx at Argonne National Laboratory and for a cluster of quasi-dedicated SUN SPARC Station 20`s. In the later portion of the paper a widely accepted communication cost model combined with Amdahl`s law is used to obtain performance predictions for uneven distributed computational work loads.

  12. A study of the efficiency of hydrogen liquefaction

    NASA Technical Reports Server (NTRS)

    Baker, C. R.; Shaner, R. L.

    1976-01-01

    The use of liquid hydrogen as a jet aircraft fuel has a number of environmental and technological advantages over conventional fuels. The liquefaction of hydrogen requires a large expenditure of energy. There are many inefficiencies that are a part of any practical liquefaction process. Current technology was investigated for the best available system. Parametric studies were made to identify where inefficiencies occur and to optimize and integrate the component parts. Flowsheets are presented for a module that produces 250 tons per day of liquid hydrogen. Approximately ten of these modules is needed for a major airport in the 1990's. The advantages of producing a product with a minimum amount of ortho to para hydrogen conversion are pointed out. The optimum degree of conversion was determined for a liquid hydrogen product that will be used within a given time. An assessment was made regarding the potentials for improvement of the processing schemes and equipment over the next 10 to 25 years.

  13. A study of improvements in silicon solar cell efficiency due to various geometrical and doping modifications

    NASA Technical Reports Server (NTRS)

    Dunbar, P. M.; Hauser, J. R.

    1976-01-01

    This paper presents the results of continued studies of silicon solar cell operation and limitations. The objective of this paper is to report on geometrical and doping changes in silicon solar cells which result in predictions of high efficiencies. Efficiencies as high as 20 per cent (uncorrected for metal coverage and ohmic sheet resistance) have been calculated for optimized cells. The conditions required to achieve these efficiency values are discussed.

  14. Validation of methodology for determination of the mercury methylation potential in sediments using radiotracers.

    PubMed

    Zizek, Suzana; Ribeiro Guevara, Sergio; Horvat, Milena

    2008-04-01

    Experiments to determine the mercury methylation potential were performed on sediments from two locations on the river Idrijca (Slovenia), differing in ambient mercury concentrations. The tracer used was the radioactive isotope (197)Hg. The benefit of using this tracer is its high specific activity, which enables spikes as low as 0.02 ng Hg(2+) g(-1) of sample to be used. It was therefore possible to compare the efficiency of the methylation potential experiments over a range of spike concentrations from picogram to microgram levels. The first part of the work aimed to validate the experimental blanks and the second part consisted of several series of incubation experiments on two different river sediments using a range of tracer additions. The results showed high variability in the obtained methylation potentials. Increasing Hg(2+) additions gave a decrease in the percentage of the tracer methylated during incubation; in absolute terms, the spikes that spanned four orders of magnitude (0.019-190 pg g(-1) of sediment slurry) resulted in MeHg formation between 0.01 and 0.1 ng MeHg g(-1) in Podroteja and Kozarska Grapa. Higher spikes resulted in slightly elevated MeHg production (up to a maximum of 0.27 ng g(-1)). The values of methylation potential were similar in both sediments. The results imply that the experimental determination of mercury methylation potential strongly depends on the experimental setup itself and the amount of tracer added to the system under study. It is therefore recommended to use different concentrations of tracer and perform the experiments in several replicates. The amount of mercury available for methylation in nature is usually very small. Therefore, adding very low amounts of tracer in the methylation potential studies probably gives results that have a higher environmental relevance. It is also suggested to express the results obtained in absolute amounts of MeHg produced and not just as the percentage of the added tracer.

  15. Test-retest reproducibility of binding parameters in humans with 11C-LY2795050, an antagonist PET radiotracer for the kappa opioid receptor

    PubMed Central

    Naganawa, Mika; Zheng, Ming-Qiang; Henry, Shannan; Nabulsi, Nabeel; Lin, Shu-Fei; Ropchan, Jim; Labaree, David; Najafzadeh, Soheila; Kapinos, Michael; Tauscher, Johannes; Neumeister, Alexander; Carson, Richard E.; Huang, Yiyun

    2015-01-01

    11C-LY2795050 is a new antagonist PET radioligand for the kappa opioid receptor (KOR). In this study, we assessed the reproducibility of the binding parameters of 11C-LY2795050 in healthy human subjects. Methods Sixteen healthy subjects (11 men, 5 women) underwent two separate 90-min PET scans with arterial input function and plasma free fraction measurements. The two-tissue compartment model and multilinear analysis-1 were applied to calculate five outcome measures in 14 brain regions: distribution volume (VT), distribution volume normalized by plasma free fraction (VT/fP), and three binding potentials (BPND, BPP, BPF). Since KOR is distributed ubiquitously throughout the brain, there are no suitable reference regions. We used a fixed fraction of individual cerebellum VT value as the non-displaceable distribution volume VND (= VT CER/1.17). The relative and absolute test-retest variability and intra-class correlation coefficient were evaluated for the outcome measures of 11C-LY2795050. Results The test-retest variability of 11C-LY2795050 for VT was ≤ 10% in all regions, and 12% in the amygdala. For binding potentials (BPND and BPP), the test-retest variability was good in regions of moderate and high KOR density (BPND > 0.4) and poor in regions of low density. Correction by fP (VT/fP or BPF) did not improve the test-retest performance. Conclusion Our results suggest that quantification of 11C-LY2795050 imaging is reproducible and reliable in the regions with moderate and high KOR density. Therefore we conclude that this first antagonist radiotracer is highly useful for PET studies of KOR. PMID:25593119

  16. Hospital competition and inpatient services efficiency in Taiwan: a longitudinal study.

    PubMed

    Chu, Chiao-Lee; Chiang, Tung-Liang; Chang, Ray-E

    2011-10-01

    There is no consistent evidence of the relationship between market competition and hospital efficiency. Some studies indicated that more competition led to a faster patient turnover rate, higher hospital costs, and lower hospital efficiency. Since the 1980s some studies found market competition could increase the efficiency of inpatient services. However, there were few studies testing the market competition during a hospital's earlier stages on its efficiency during later stages, or the dynamic of efficiency. In this study, we examined the effect of early-stage market competition on later-stage hospital efficiency in Taiwan, and we determine the efficiency change using longitudinal study design. The data for the analysis came from the annual national hospital survey of 1996 and 2001 provided by the Department of Health. There were 102 teaching hospital be analysed. The results show that no evidence supports the proposition that higher market competition would improve the efficiency of hospitals in delivering inpatient services in Taiwan. Importantly, neither was the inefficiency score nor the Malmquist productivity index of inpatient services associated with the level of hospital market competition, regardless of the adjustment for hospital characteristics. However, the results may be related with the hospital increasing beds investment behavior. Copyright © 2010 John Wiley & Sons, Ltd.

  17. BWR Spent Nuclear Fuel Interfacial Bonding Efficiency Study

    SciTech Connect

    Wang, Jy-An John; Jiang, Hao

    2015-04-30

    The objective of this project is to perform a systematic study of spent nuclear fuel (SNF, also known as “used nuclear fuel” [UNF]) integrity under simulated transportation environments using the Cyclic Integrated Reversible-Bending Fatigue Tester (CIRFT) hot-cell testing technology developed at Oak Ridge National Laboratory (ORNL) in August 2013. Under Nuclear Regulatory Commission (NRC) sponsorship, ORNL completed four benchmark tests, four static tests, and twelve dynamic or cycle tests on H. B. Robinson (HBR) high burn-up (HBU) fuel. The clad of the HBR fuels was made of Zircaloy-4. Testing was continued in fiscal year (FY) 2014 using Department of Energy (DOE) funds. Additional CIRFT testing was conducted on three HBR rods; two specimens failed, and one specimen was tested to over 2.23 × 107 cycles without failing. The data analysis on all the HBR SNF rods demonstrated that it is necessary to characterize the fatigue life of the SNF rods in terms of (1) the curvature amplitude and (2) the maximum absolute of curvature extremes. The maximum extremes are significant because they signify the maximum tensile stress for the outer fiber of the bending rod. CIRFT testing has also addressed a large variation in hydrogen content on the HBR rods. While the load amplitude is the dominant factor that controls the fatigue life of bending rods, the hydrogen content also has an important effect on the lifetime attained at each load range tested. In FY 15, eleven SNF rod segments from the Limerick BWR were tested using the ORNL CIRFT equipment; one test under static conditions and ten tests under dynamic loading conditions. Under static unidirectional loading, a moment of 85 N·m was obtained at a maximum curvature of 4.0 m-1. The specimen did not show any sign of failure during three repeated loading cycles to a similar maximum curvature. Ten cyclic tests were conducted with amplitudes varying from 15.2 to 7.1 N·m. Failure was observed in nine of

  18. Transfection efficiency of chitosan and thiolated chitosan in retinal pigment epithelium cells: A comparative study

    PubMed Central

    Oliveira, Ana V.; Silva, Andreia P.; Bitoque, Diogo B.; Silva, Gabriela A.; Rosa da Costa, Ana M.

    2013-01-01

    OBJECTIVE: Gene therapy relies on efficient vector for a therapeutic effect. Efficient non-viral vectors are sought as an alternative to viral vectors. Chitosan, a cationic polymer, has been studied for its gene delivery potential. In this work, disulfide bond containing groups were covalently added to chitosan to improve the transfection efficiency. These bonds can be cleaved by cytoplasmic glutathione, thus, releasing the DNA load more efficiently. MATERIALS AND METHODS: Chitosan and thiolated chitosan nanoparticles (NPs) were prepared in order to obtain a NH3+:PO4− ratio of 5:1 and characterized for plasmid DNA complexation and release efficiency. Cytotoxicity and gene delivery studies were carried out on retinal pigment epithelial cells. RESULTS: In this work, we show that chitosan was effectively modified to incorporate a disulfide bond. The transfection efficiency of chitosan and thiolated chitosan varied according to the cell line used, however, thiolation did not seem to significantly improve transfection efficiency. CONCLUSION: The apparent lack of improvement in transfection efficiency of the thiolated chitosan NPs is most likely due to its size increase and charge inversion relatively to chitosan. Therefore, for retinal cells, thiolated chitosan does not seem to constitute an efficient strategy for gene delivery. PMID:23833516

  19. How efficient are Greek hospitals? A case study using a double bootstrap DEA approach.

    PubMed

    Kounetas, Kostas; Papathanassopoulos, Fotis

    2013-12-01

    The purpose of this study was to measure Greek hospital performance using different input-output combinations, and to identify the factors that influence their efficiency thus providing policy makers with valuable input for the decision-making process. Using a unique dataset, we estimated the productive efficiency of each hospital through a bootstrapped data envelopment analysis (DEA) approach. In a second stage, we explored, using a bootstrapped truncated regression, the impact of environmental factors on hospitals' technical and scale efficiency. Our results reveal that over 80% of the examined hospitals appear to have a technical efficiency lower than 0.8, while the majority appear to be scale efficient. Moreover, efficiency performance differed with inclusion of medical examinations as an additional variable. On the other hand, bed occupancy ratio appeared to affect both technical and scale efficiency in a rather interesting way, while the adoption of advanced medical equipment and the type of hospital improves scale and technical efficiency, correspondingly. The findings of this study on Greek hospitals' performance are not encouraging. Furthermore, our results raise questions regarding the number of hospitals that should operate, and which type of hospital is more efficient. Finally, the results indicate the role of medical equipment in performance, confirming its misallocation in healthcare expenditure.

  20. 17-[4-(2-[18F]fluoroethyl)-1H-1,2,3-triazol-1-yl]-6-thia-heptadecanoic acid: a potential radiotracer for the evaluation of myocardial fatty acid metabolism.

    PubMed

    Kim, Dong Hyun; Choe, Yearn Seong; Choi, Joon Young; Choi, Yong; Lee, Kyung-Han; Kim, Byung-Tae

    2009-06-01

    In this study, we synthesized 17-[4-(2-[(18)F]fluoroethyl)-1H-1,2,3-triazol-1-yl]-6-thia-heptadecanoic acid ([(18)F]1), a PET radiotracer for the evaluation of fatty acid metabolism. [(18)F]1 was synthesized in 20-26% decay-corrected radiochemical yields from 17-azido 6-thia-heptadecanoic acid (9) and 4-[(18)F]fluoro-1-butyne using click chemistry. The tissue distribution of [(18)F]1 in mice showed high radioactivity accumulation in heart (3.70%ID/g at 1 min, 3.28%ID/g at 10 min, and 3.01%ID/g at 60 min postinjection), a prolonged myocardial elimination half-life (>60 min), and a maximal heart-to-blood uptake ratio at 5 min postinjection (5.55). Pretreatment with etomoxir, a carnitine palmitoyl transferase (CPT) I inhibitor, reduced myocardial radioactivity uptake at 30 min postinjection by 53%, suggesting that [(18)F]1 was transported into the mitochondria. Analyses of heart tissue samples showed that most of the radioactivity was present in a tissue pellet (62-63%) after homogenization in CHCl(3)-CH(3)OH followed by extraction with 40% urea and 5% H(2)SO(4), which was mostly precipitated with addition of 50% trichloroacetic acid (TCA). These results suggest that [(18)F]1 undergoes metabolic trapping via beta-oxidation in myocardium and, thus, suggest that it has potential use as a PET radiotracer for the evaluation of myocardial fatty acid metabolism.

  1. Efficiency of a Care Coordination Model: A Randomized Study with Stroke Patients

    ERIC Educational Resources Information Center

    Claiborne, Nancy

    2006-01-01

    Objectives: This study investigated the efficiency of a social work care coordination model for stroke patients. Care coordination addresses patient care and treatment resources across the health care system to reduce risk, improve clinical outcomes, and maximize efficiency. Method: A randomly assigned, pre-post experimental design measured…

  2. Efficiency of a Care Coordination Model: A Randomized Study with Stroke Patients

    ERIC Educational Resources Information Center

    Claiborne, Nancy

    2006-01-01

    Objectives: This study investigated the efficiency of a social work care coordination model for stroke patients. Care coordination addresses patient care and treatment resources across the health care system to reduce risk, improve clinical outcomes, and maximize efficiency. Method: A randomly assigned, pre-post experimental design measured…

  3. Gallium(III) complexes of NOTA-bis (phosphonate) conjugates as PET radiotracers for bone imaging.

    PubMed

    Holub, Jan; Meckel, Marian; Kubíček, Vojtěch; Rösch, Frank; Hermann, Petr

    2015-01-01

    Ligands with geminal bis(phosphonic acid) appended to 1,4,7-triazacyclonone-1,4-diacetic acid fragment through acetamide (NOTAM(BP) ) or methylenephosphinate (NO2AP(BP) ) spacers designed for (68) Ga were prepared. Ga(III) complexation is much faster for ligand with methylenephosphinate spacer than that with acetamide one, in both chemical (high reactant concentrations) and radiolabeling studies with no-carrier-added (68) Ga. For both ligands, formation of Ga(III) complex was slower than that with NOTA owing to the strong out-of-cage binding of bis(phosphonate) group. Radiolabeling was efficient and fast only above 60 °C and in a narrow acidity region (pH ~3). At higher temperature, hydrolysis of amide bond of the carboxamide-bis(phosphonate) conjugate was observed during complexation reaction leading to Ga-NOTA complex. In vitro sorption studies confirmed effective binding of the (68) Ga complexes to hydroxyapatite being comparable with that found for common bis(phosphonate) drugs such as pamindronate. Selective bone uptake was confirmed in healthy rats by biodistribution studies ex vivo and by positron emission tomography imaging in vivo. Bone uptake was very high, with SUV (standardized uptake value) of 6.19 ± 1.27 for [(68) Ga]NO2AP(BP) ) at 60 min p.i., which is superior to uptake of (68) Ga-DOTA-based bis(phosphonates) and [(18) F]NaF reported earlier (SUV of 4.63 ± 0.38 and SUV of 4.87 ± 0.32 for [(68) Ga]DO3AP(BP) and [(18) F]NaF, respectively, at 60 min p.i.). Coincidently, accumulation in soft tissue is generally low (e.g. for kidneys SUV of 0.26 ± 0.09 for [(68) Ga]NO2AP(BP) at 60 min p.i.), revealing the new (68) Ga complexes as ideal tracers for noninvasive, fast and quantitative imaging of calcified tissue and for metastatic lesions using PET or PET/CT. Copyright © 2014 John Wiley & Sons, Ltd.

  4. Radiosynthesis and evaluation of a (99m)Tc-folic acid radiotracer prepared using [(99m)TcN(PNP)](2+) metal fragment.

    PubMed

    Vats, Kusum; Subramanian, Suresh; Mathur, Anupam; Sarma, Haladhar Dev; Banerjee, Sharmila

    2017-03-01

    Folate receptors (FR) are over-expressed on a wide variety of tumor cells and are a potential molecular target for radiolabeled folates. In this respect, several SPECT and PET based radiofolates have been evaluated in the past albeit with their high renal uptake posing limitation towards their clinical use. To overcome this, a new (99m)Tc labeled folic acid was synthesized via the use of [(99m)TcN(PNP)](2+) metal fragment, where the presence of the latter pharmacophore redirects in vivo clearance via the hepatobiliary pathway. In this respect, folic acid was derivatized at the γ-acid group with a cysteine BFCA (bifunctional chelating agent) and subsequently reacted with the preformed [(99m)TcN](2+) intermediate in presence of PNP2 (bisphosphine) ligand, to yield the final complex. While preliminary, in vivo distribution of the complex exhibited high association of activity with liver and intestines and provided support to the rationality of the present design as clearance of labeled folic acid could be effected via the hepatic route, the in vitro studies of the folic acid-cysteine conjugate carried out in KB-31 cells, did not show much promise with reduction in receptor affinity in comparison with the native folic acid. The route followed herein to prepare a folic-acid based radiotracer constitutes the first report of radiolabeling folic acid using the [(99m)TcN(PNP)](2+) as a radiosynthon. Modification in the structure of conjugate by linking the BFCA through a long-chain linker can be envisaged to improve the affinity of [(99m)TcN(PNP)]-folic acid complex towards FRs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Investigating the binding properties of porous drug delivery systems using nuclear sensors (radiotracers) and positron annihilation lifetime spectroscopy--predicting conditions for optimum performance.

    PubMed

    Mume, Eskender; Lynch, Daniel E; Uedono, Akira; Smith, Suzanne V

    2011-06-21

    Understanding how the size, charge and number of available pores in porous material influences the uptake and release properties is important for optimising their design and ultimately their application. Unfortunately there are no standard methods for screening porous materials in solution and therefore formulations must be developed for each encapsulated agent. This study investigates the potential of a library of radiotracers (nuclear sensors) for assessing the binding properties of hollow silica shell materials. Uptake and release of Cu(2+) and Co(2+) and their respective complexes with polyazacarboxylate macrocycles (dota and teta) and a series of hexa aza cages (diamsar, sarar and bis-(p-aminobenzyl)-diamsar) from the hollow silica shells was monitored using their radioisotopic analogues. Coordination chemistry of the metal (M) species, subtle alterations in the molecular architecture of ligands (Ligand) and their resultant complexes (M-Ligand) were found to significantly influence their uptake over pH 3 to 9 at room temperature. Positively charged species were selectively and rapidly (within 10 min) absorbed at pH 7 to 9. Negatively charged species were preferentially absorbed at low pH (3 to 5). Rates of release varied for each nuclear sensor, and time to establish equilibrium varied from minutes to days. The subtle changes in design of the nuclear sensors proved to be a valuable tool for determining the binding properties of porous materials. The data support the development of a library of nuclear sensors for screening porous materials for use in optimising the design of porous materials and the potential of nuclear sensors for high through-put screening of materials.

  6. The Multidimensional Efficiency of Pension System: Definition and Measurement in Cross-Country Studies.

    PubMed

    Chybalski, Filip

    The existing literature on the efficiency of pension system, usually addresses the problem between the choice of different theoretical models, or concerns one or few empirical pension systems. In this paper quite different approach to the measurement of pension system efficiency is proposed. It is dedicated mainly to the cross-country studies of empirical pension systems, however it may be also employed to the analysis of a given pension system on the basis of time series. I identify four dimensions of pension system efficiency, referring to: GDP-distribution, adequacy of pension, influence on the labour market and administrative costs. Consequently, I propose four sets of static and one set of dynamic efficiency indicators. In the empirical part of the paper, I use Spearman's rank correlation coefficient and cluster analysis to verify the proposed method on statistical data covering 28 European countries in years 2007-2011. I prove that the method works and enables some comparisons as well as clustering of analyzed pension systems. The study delivers also some interesting empirical findings. The main goal of pension systems seems to become poverty alleviation, since the efficiency of ensuring protection against poverty, as well as the efficiency of reducing poverty, is very resistant to the efficiency of GDP-distribution. The opposite situation characterizes the efficiency of consumption smoothing-this is generally sensitive to the efficiency of GDP-distribution, and its dynamics are sensitive to the dynamics of GDP-distribution efficiency. The results of the study indicate the Norwegian and the Icelandic pension systems to be the most efficient in the analyzed group.

  7. The Super Efficient Refrigerator Program: Case study of a Golden Carrot program

    SciTech Connect

    Eckert, J B

    1995-07-01

    The work in this report was conducted by the Analytic Studies Division (ASD) of the National Renewable Energy Laboratory (NREL) for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Office of Building Technologies. This case study describes the development and implementation of the Super Efficient Refrigerator Program (SERP), which awarded $30 million to the refrigerator manufacturer that developed and commercialized a refrigerator that exceeded 1993 federal efficiency standards by at least 25%. The program was funded by 24 public and private utilities. As the first Golden Carrot program to be implemented in the United States, SERP was studied as an example for future `market-pull` efforts.

  8. Technology Efficiency Study on Nuclear Power and Coal Power in Guangdong Province Based on DEA

    SciTech Connect

    Yinong Li; Dong Wang

    2006-07-01

    Guangdong Province has taken the lead in embarking on nuclear power development to resolve its dire lack of primary resources. With the deepening of the on-going structural reform in the electric power sector in China, the market competition scheme is putting electricity generation enterprises under severe strain. Consequently, it is incumbent upon the nuclear power producers to steadily upgrade management, enhance technical capabilities, reduce cost and improve efficiency. At present, gradual application of such efficiency evaluation methodology has already commenced in some sectors in China including the electric power industry. The purpose of this paper is to use the Data Envelopment Analysis (DEA), which is a cutting-edge approach in the efficiency evaluation field - to study the technological efficiency between nuclear power and coal power in Guangdong Province. The DEA results demonstrate that, as far as Guangdong Province is concerned, the technological efficiency of nuclear power is higher than that of coal power in terms of Technological Efficiency (TE), Pure Technology Efficiency (PTE) and Scale Efficiency (SE). The reason is that nuclear power technology is advanced with a much higher equipment availability factor. Under the same scale, the generation output of nuclear power is far higher than that of equivalent coal power generation. With the environmental protection and sustainable development requirements taken into full account, nuclear power constitutes a clean, safe and highly-efficient energy form which should be extensively harnessed in Guangdong Province to fuel its future continuing economic growth. (authors)

  9. Voxel-based analysis of Alzheimer's disease PET imaging using a triplet of radiotracers: PIB, FDDNP, and FDG.

    PubMed

    Shin, Jonghan; Lee, Sang-Yoon; Kim, Seog Ju; Kim, So-Hee; Cho, Seong-Jin; Kim, Young-Bo

    2010-08-15

    Beta amyloid plaques, neurofibrillary tangles, and impaired glucose metabolism are among the most prevalent pathological characteristics of Alzheimer's disease (AD). However, separate visualization of these three AD-related pathologies in living humans has not been conducted. Here, we show that positron emission tomography (PET) imaging using the three radiotracers (11)C-Pittsburgh compound B (PIB), 2-(1-{6-[(2-(18)F-fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene) malononitrile (FDDNP), and 2-[18F]fluoro-2-deoxy-d-glucose (FDG), in the same subjects, with and without AD, can provide valuable information on the pathological patterns of the distribution of tracers for amyloid plaque, neurofibrillary tangle, and glucose hypometabolism in AD. Voxel-based analysis of PIB-PET in patients with AD compared with normal control subjects showed that patients with AD have highly significant PIB retention in brain regions known to have high amyloid plaque deposition (e.g., frontal, parietal, temporal, and posterior cingulate/precuneus cortices). In contrast, voxel-based analysis of FDDNP-PET showed significantly high FDDNP binding in some brain regions known to have high tangle accumulation in patients with AD compared with age-matched normal subjects (e.g., entorhinal cortex, inferior temporal gyrus, and secondary visual cortex). In addition, because FDDNP binds both plaques and tangles but PIB binds plaques specifically, we examined subtracted PET data (FDDNP minus PIB) acquired from the same patients with AD using an SPM analysis. We found that the hippocampal formation was the most significant brain region in the voxel mapping of FDDNP minus PIB in the same patients with AD. Voxel-based analysis of FDG-PET in the same subjects revealed that brain regions with glucose hypometabolism in patients with AD overlap with regions of high PIB binding. In conclusion, PET imaging using these three radiotracers in the same subjects may contribute toward developing and testing disease

  10. Robust Timing Synchronization for Aviation Communications, and Efficient Modulation and Coding Study for Quantum Communication

    NASA Technical Reports Server (NTRS)

    Xiong, Fugin

    2003-01-01

    One half of Professor Xiong's effort will investigate robust timing synchronization schemes for dynamically varying characteristics of aviation communication channels. The other half of his time will focus on efficient modulation and coding study for the emerging quantum communications.

  11. Robust Timing Synchronization for Aviation Communications, and Efficient Modulation and Coding Study for Quantum Communication

    NASA Technical Reports Server (NTRS)

    Xiong, Fugin

    2003-01-01

    One half of Professor Xiong's effort will investigate robust timing synchronization schemes for dynamically varying characteristics of aviation communication channels. The other half of his time will focus on efficient modulation and coding study for the emerging quantum communications.

  12. Experimental studies of silver iodide pyrotechnic aerosol ice forming efficiency dynamics

    NASA Astrophysics Data System (ADS)

    Shilin, A. G.; Drofa, A. S.; Ivanov, V. N.; Savchenko, A. V.; Shilin, V. A.

    2013-05-01

    The study concerns the problems connected with the temporal variability of aerosol ice forming activity at introduction into the sub-cloud layer and the comparison of aerosol efficiency of produced pyrotechnic mixtures with different silver contents.

  13. Medium and High Altitude Unmanned Aircraft System Acquisition: An Efficiency Study of Magnitude and Capability

    DTIC Science & Technology

    2009-06-12

    measures associated with a single entity acquisition authority for the selection of medium and high altitude UAS programs. Secondly, there will be no...MEDIUM AND HIGH ALTITUDE UNMANNED AIRCRAFT SYSTEM ACQUISITION : AN EFFICIENCY STUDY OF MAGNITUDE AND CAPABILITY A thesis...To) AUG 2009 – JUN 2009 4. TITLE AND SUBTITLE MEDIUM AND HIGH ALTITUDE UNMANNED AIRCRAFT SYSTEM (UAS) ACQUISITION : AN EFFICIENCY STUDY OF

  14. Development of the brain's structural network efficiency in early adolescence: A longitudinal DTI twin study.

    PubMed

    Koenis, Marinka M G; Brouwer, Rachel M; van den Heuvel, Martijn P; Mandl, René C W; van Soelen, Inge L C; Kahn, René S; Boomsma, Dorret I; Hulshoff Pol, Hilleke E

    2015-12-01

    The brain is a network and our intelligence depends in part on the efficiency of this network. The network of adolescents differs from that of adults suggesting developmental changes. However, whether the network changes over time at the individual level and, if so, how this relates to intelligence, is unresolved in adolescence. In addition, the influence of genetic factors in the developing network is not known. Therefore, in a longitudinal study of 162 healthy adolescent twins and their siblings (mean age at baseline 9.9 [range 9.0-15.0] years), we mapped local and global structural network efficiency of cerebral fiber pathways (weighted with mean FA and streamline count) and assessed intelligence over a three-year interval. We find that the efficiency of the brain's structural network is highly heritable (locally up to 74%). FA-based local and global efficiency increases during early adolescence. Streamline count based local efficiency both increases and decreases, and global efficiency reorganizes to a net decrease. Local FA-based efficiency was correlated to IQ. Moreover, increases in FA-based network efficiency (global and local) and decreases in streamline count based local efficiency are related to increases in intellectual functioning. Individual changes in intelligence and local FA-based efficiency appear to go hand in hand in frontal and temporal areas. More widespread local decreases in streamline count based efficiency (frontal cingulate and occipital) are correlated with increases in intelligence. We conclude that the teenage brain is a network in progress in which individual differences in maturation relate to level of intellectual functioning.

  15. Radiotracer Evaluation of the Contribution of Degradation Products of Phenolic Resins to the Poisoning of Electrodes in the 190 C Hydrogen/Air Fuel Cell.

    DTIC Science & Technology

    1980-12-01

    R.F. Pascoe , H.R. Kunz, "Surface Area Loss of Platinum Supported on Carbon in Phosphoric Acid Electrolyte", J. Electrochem. Soc. 127, 1219 (1980). 4...1a. SUPPLEMENTARY NOTES IS. KEY WORDS (Contin he a reverse side It noceasm, mid Identify by block number) Fuel cells, phosphoric acid , bipolar...plates, phenolic resins, composite graphite, Carbon-14, radiotracer, electro-catalyst, electrode poisoning, platinum on carbon catalyst, acid -resistant

  16. Whole-body biodistribution and dosimetry estimates of a novel radiotracer for imaging of serotonin 4 receptors in brain: [¹⁸F]MNI-698.

    PubMed

    Tavares, Adriana Alexandre S; Caillé, Fabien; Barret, Olivier; Papin, Caroline; Lee, Hsiaoju; Morley, Thomas J; Fowles, Krista; Holden, Daniel; Seibyl, John P; Alagille, David; Tamagnan, Gilles D

    2014-01-01

    A new radiotracer for imaging the serotonin 4 receptors (5-HT4) in brain, [¹⁸F]MNI-698, was recently developed by our group. Evaluation in nonhuman primates indicates the novel radiotracer holds promise as an imaging agent of 5-HT4 in brain. This paper aims to describe the whole-body biodistribution and dosimetry estimates of [¹⁸F]MNI-698. Whole-body positron emission tomography (PET) images were acquired over 240 minutes after intravenous bolus injection of [¹⁸F]MNI-698 in adult rhesus monkeys. Different models were investigated for quantification of radiation absorbed and effective doses using OLINDA/EXM 1.0 software. The radiotracer main elimination route was found to be urinary and the critical organ was the urinary bladder. Modeling of the urinary bladder voiding interval had a considerable effect on the estimated effective dose. Normalization of rhesus monkeys' organs and whole-body masses to human equivalent reduced the calculated dosimetry values. The effective dose ranged between 0.017 and 0.027 mSv/MBq. The dosimetry estimates, obtained when normalizing organ and whole-body weights and applying the urinary bladder model, indicate that the radiation doses from [¹⁸F]MNI-698 comply with limits and guidelines recommended by key regulatory authorities that govern the translation of radiotracers to human clinical trials. The timing of urinary bladder emptying should be considered when designing future clinical protocols with [¹⁸F]MNI-698, in order to minimize the subject absorbed doses. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. In vitro and in vivo properties of (/sup 125/I) (R,S) 4IQNB: A lower affinity diastereomeric muscarinic receptor radiotracer

    SciTech Connect

    Gibson, R.E.; Schneidau, T.A.; Rzeszotarski, W.J.; Cohen, V.I.; Eckelman, W.C.; Reba, R.C.

    1985-05-01

    The (R,R) diastereomer of 3-Quinuclidinyl 4-Iodobenzilate (4IQNB) is a high affinity muscarinic acetylcholine receptor radiotracer which has provided images of receptor distribution in the CNS of man. The radiotracer is of such high affinity that dissociation in vivo is not evident in man after 6-half-lives I-123. Since the dissociation kinetics of radiotracer may be helpful for receptor quantitation, the authors have prepared (/sup 125/I) (R,S) 4IQNB: a diastereomer of 4IQNB which as a lower affinity for the m-AChR than the (R,R) isomer. The equilibrium association constant for the (R,S) diastereomer is 1.10 x 10/sup 9/ M/sup -1/, which is 4-fold lower in affinity than (/sup 3/H) (R) QNB and 2-fold lower than that of the (R,R) 4IQNB. Of more interest, the dissociation rate constant of (R,S) 4IQNB is 0.099 (+0.01)/min., 15-fold more rapid than that of the (R,R) isomer. The systemic distribution of (R,S) 4IQNB is similar to that of (R,R) 4IQNB except localization in the myocardium is 2-fold lower, reflecting the lower affinity. Nonreceptor interactions are the same since the compounds differ only as optical isomers around the carbinol chiral center. In the CNS peak activities are obtained in the corpus striatum (and other M/sub 1/-receptor rich structures) which are the same as obtained with (R,R) 4IQNB. However, no washout of (R,R) 4IQNB is observed after 4 hrs and only 60% in 24 hrs. By contrast, 65% of (R,S) 4IQNB washes out in 4 hrs and no significant activity is detected after 24 hrs. The increased washout kinetics should provide a better radiotracer for determining muscarinic receptor concentrations in the CNS of man.

  18. The efficiency and budgeting of public hospitals: case study of iran.

    PubMed

    Yusefzadeh, Hasan; Ghaderi, Hossein; Bagherzade, Rafat; Barouni, Mohsen

    2013-05-01

    Hospitals are the most costly and important components of any health care system, so it is important to know their economic values, pay attention to their efficiency and consider factors affecting them. The aim of this study was to assess the technical scale and economic efficiency of hospitals in the West Azerbaijan province of Iran, for which Data Envelopment Analysis (DEA) was used to propose a model for operational budgeting. This study was a descriptive-analysis that was conducted in 2009 and had three inputs and two outputs. Deap2, 1 software was used for data analysis. Slack and radial movements and surplus of inputs were calculated for selected hospitals. Finally, a model was proposed for performance-based budgeting of hospitals and health sectors using the DEA technique. The average scores of technical efficiency, pure technical efficiency (managerial efficiency) and scale efficiency of hospitals were 0.584, 0.782 and 0.771, respectively. In other words the capacity of efficiency promotion in hospitals without any increase in costs and with the same amount of inputs was about 41.5%. Only four hospitals among all hospitals had the maximum level of technical efficiency. Moreover, surplus production factors were evident in these hospitals. Reduction of surplus production factors through comprehensive planning based on the results of the Data Envelopment Analysis can play a major role in cost reduction of hospitals and health sectors. In hospitals with a technical efficiency score of less than one, the original and projected values of inputs were different; resulting in a surplus. Hence, these hospitals should reduce their values of inputs to achieve maximum efficiency and optimal performance. The results of this method was applied to hospitals a benchmark for making decisions about resource allocation; linking budgets to performance results; and controlling and improving hospitals performance.

  19. Efficiency and quality of care in nursing homes: an Italian case study.

    PubMed

    Garavaglia, Giulia; Lettieri, Emanuele; Agasisti, Tommaso; Lopez, Silvano

    2011-03-01

    This study investigates efficiency and quality of care in nursing homes. By means of Data Envelopment Analysis (DEA), the efficiency of 40 nursing homes that deliver their services in the north-western area of the Lombardy Region was assessed over a 3-year period (2005-2007). Lombardy is a very peculiar setting, since it is the only Region in Italy where the healthcare industry is organised as a quasi-market, in which the public authority buys health and nursing services from independent providers-establishing a reimbursement system for this purpose. The analysis is conducted by generating bootstrapped DEA efficiency scores for each nursing home (stage one), then regressing those scores on explanatory variables (stage two). Our DEA model employed two input (i.e. costs for health and nursing services and costs for residential services) and three output variables (case mix, extra nursing hours and residential charges). In the second-stage analysis, Tobit regressions and the Kruskall-Wallis tests of hypothesis to the efficiency scores were applied to define what are the factors that affect efficiency: (a) the ownership (private nursing houses outperform their public counterparts); and (b) the capability to implement strategies for labour cost and nursing costs containment, since the efficiency heavily depends upon the alignment of the costs to the public reimbursement system. Lastly, even though the public institutions are less efficient than the private ones, the results suggest that public nursing homes are moving towards their private counterparts, and thus competition is benefiting efficiency.

  20. Measuring efficiency of cotton cultivation in Pakistan: a restricted production frontier study.

    PubMed

    Watto, Muhammad Arif; Mugera, Amin

    2014-11-01

    Massive groundwater pumping for irrigation has started lowering water tables rapidly in different regions of Pakistan. Declining water tables have thus prompted research efforts to improve agricultural productivity and efficiency to make efficient use of scarce water resources. This study employs a restricted stochastic production frontier to estimate the level of, and factors affecting, technical efficiency of groundwater-irrigated cotton farms in the Punjab province of Pakistan. The mean technical efficiency estimates indicate substantial technical inefficiencies among cotton growers. On average, tube-well owners and water buyers can potentially increase cotton production by 19% and 28%, respectively, without increasing the existing input level. The most influential factors affecting technical efficiency positively are the use of improved quality seed, consultation with extension field staff and farmers' perceptions concerning the availability of groundwater resources for irrigation in the future. This study proposes that adopting improved seed for new cotton varieties and providing better extension services regarding cotton production technology would help to achieve higher efficiency in cotton farming. Within the context of falling water tables, educating farmers about the actual crop water requirements and guiding them about groundwater resource availability may also help to achieve higher efficiencies. © 2014 Society of Chemical Industry. © 2014 Society of Chemical Industry.

  1. Investigation of holdup and axial dispersion of liquid phase in a catalytic exchange column using radiotracer technique.

    PubMed

    Kumar, Rajesh; Pant, H J; Goswami, Sunil; Sharma, V K; Dash, A; Mishra, S; Bhanja, K; Mohan, Sadhana; Mahajani, S M

    2017-03-01

    Holdup and axial dispersion of liquid phase in a catalytic exchange column were investigated by measuring residence time distributions (RTD) using a radiotracer technique. RTD experiments were independently carried out with two different types of packings i.e. hydrophobic water-repellent supported platinum catalyst and a mixture (50% (v/v)) of hydrophobic catalyst and a hydrophillic wettable packing were used in the column. Mean residence times and hold-ups of the liquid phase were estimated at different operating conditions. Axial dispersion model (ADM) and axial dispersion with exchange model (ADEM) were used to simulate the measured RTD data. Both the models were found equally suitable to describe the measured data. The degree of axial mixing was estimated in terms of Peclet number (Pe) and Bodenstein number (Bo). Based on the obtained parameters of the ADM, correlations for total liquid hold-up (HT) and axial mixing in terms of Bo were proposed for design and scale up of the full-scale catalytic exchange column.

  2. Structural efficiency studies of corrugated compression panels with curved caps and beaded webs

    NASA Technical Reports Server (NTRS)

    Davis, R. C.; Mills, C. T.; Prabhakaran, R.; Jackson, L. R.

    1984-01-01

    Curved cross-sectional elements are employed in structural concepts for minimum-mass compression panels. Corrugated panel concepts with curved caps and beaded webs are optimized by using a nonlinear mathematical programming procedure and a rigorous buckling analysis. These panel geometries are shown to have superior structural efficiencies compared with known concepts published in the literature. Fabrication of these efficient corrugation concepts became possible by advances made in the art of superplastically forming of metals. Results of the mass optimization studies of the concepts are presented as structural efficiency charts for axial compression.

  3. Synthesis and evaluation of an (125)I-labeled azide prosthetic group for efficient and bioorthogonal radiolabeling of cyclooctyne-group containing molecules using copper-free click reaction.

    PubMed

    Choi, Mi Hee; Shim, Ha Eun; Nam, You Ree; Kim, Hye Rim; Kang, Jung Ae; Lee, Dong-Eun; Park, Sang Hyun; Choi, Dae Seong; Jang, Beom-Su; Jeon, Jongho

    2016-02-01

    Herein we report the radiosynthesis of a pyridine derived azide prosthetic group for iodine radioisotope labeling of dibenzocyclooctyne (DBCO) conjugated molecules. The radiolabeling of the stannylated precursor 2 was conducted using [(125)I]NaI and chloramine-T to give (125)I-labeled azide ([(125)I]1) with high radiochemical yield (72±8%, n=4) and radiochemical purity (>99%). Using (125)I-labeled azide ([(125)I]1), cyclic RGD peptide and near infrared fluorescent molecule were efficiently labeled with modest to good radiochemical yields. The biodistribution study and SPECT/CT images showed that [(125)I]1 underwent rapid renal clearance. These results clearly demonstrated that [(125)I]1 could be used as an useful radiotracer for in vivo pre-targeted imaging as well as efficient in vitro radiolabeling of DBCO containing molecules.

  4. Efficient multivariate linear mixed model algorithms for genome-wide association studies.

    PubMed

    Zhou, Xiang; Stephens, Matthew

    2014-04-01

    Multivariate linear mixed models (mvLMMs) are powerful tools for testing associations between single-nucleotide polymorphisms and multiple correlated phenotypes while controlling for population stratification in genome-wide association studies. We present efficient algorithms in the genome-wide efficient mixed model association (GEMMA) software for fitting mvLMMs and computing likelihood ratio tests. These algorithms offer improved computation speed, power and P-value calibration over existing methods, and can deal with more than two phenotypes.

  5. A study of the efficiency of hydrogen liquefaction. [jet aircraft applications

    NASA Technical Reports Server (NTRS)

    Baker, C. R.; Shaner, R. L.

    1976-01-01

    The search for an environmentally acceptable fuel to eventually replace petroleum-based fuels for long-range jet aircraft has singled out liquid hydrogen as an outstanding candidate. Hydrogen liquefaction is discussed, along with the effect of several operating parameters on process efficiency. A feasible large-scale commercial hydrogen liquefaction facility based on the results of the efficiency study is described. Potential future improvements in hydrogen liquefaction are noted.

  6. Case Studies in the Field of Marketing Education: Learner Impact, Case Performance, and Cost Efficiency

    ERIC Educational Resources Information Center

    Spais, George S.

    2005-01-01

    The major objective of this study is to identify a methodology that will help educators in marketing to efficiently manage the design, impact, and cost of case studies. It is my intention is to examine the impact of case study characteristics in relation to the degree of learner involvement in the learning process. The author proposes that…

  7. No change in energy efficiency in lactation: Insights from a longitudinal study.

    PubMed

    Bender, Richard L; Williams, Heather S; Dufour, Darna L

    2017-08-17

    Lactation is the most energy-demanding phase of reproduction for human females, but it is still unclear how women in different environments are able to meet this additional energy demand. Previous studies have investigated whether changes in metabolism could have an energy-sparing effect in lactation, with conflicting results. Here, we asked whether increased energy efficiency in physical activity serves as an energy-sparing mechanism in lactation. We used a longitudinal design with a control group. Participants were 33 well-nourished, exclusively breastfeeding women and 29 non-pregnant, non-lactating (NPNL) controls aged 32 ± 4 years. Lactating women were measured at peak- and post-lactation. NPNL controls completed a baseline measurement and a follow-up visit. Energy efficiency in physical activity was assessed using a graded submaximal exercise test and calculated as delta efficiency (change in work accomplished over change in energy expended) and gross efficiency (work accomplished over energy expended). There was no significant change in either delta efficiency or gross efficiency from peak to post lactation in lactating women, and no significant difference in delta efficiency between lactating women and NPNL controls at any time period. However, lactating women showed greater between-visit variation in delta efficiency than the NPNL controls. Additionally, 79% of lactating participants lost weight between visits (mean weight loss -3.6 ± 2.3kg), consistent with a mobilization of body tissues to support lactation. We found no support for the idea that lactating women undergo an increase in energy efficiency to support the energy costs of lactation. © 2017 Wiley Periodicals, Inc.

  8. Study of the separation efficiency of a demister vane with response surface methodology.

    PubMed

    Zhao, Jianzhi; Jin, Baosheng; Zhong, Zhaoping

    2007-08-17

    Numerical simulations of a demister vane with various geometries and operating conditions were performed to study the separation efficiency. The numerical solutions were carried out using commercial CFD code Fluent 6.1. A prediction model of the separation efficiency was obtained based on response surface methodology by means of the statistical software program Minitab V14. The results show that not only the vane spacing and flue gas velocity, but also vane height (including height of curve and upright region) and vane turning angles, play an important role in influencing the separation efficiency. Compared with some experimental and simulative conclusions, the results indicate that present prediction model can estimate the effects of different geometries and operation conditions on the separation efficiency, and can direct the optimum design of demisters.

  9. Shuttle Ground Operations Efficiencies/Technologies (SGOE/T) study. Volume 1: Executive summary

    NASA Technical Reports Server (NTRS)

    Scholz, A. L.; Hart, M. T.; Lowry, D. J.

    1987-01-01

    Methods and technolgoy were defined to reduce the overall operations cost of a major space program. Space Shuttle processing at Kennedy Space Center (KSC) was designed as the working model that would be the source of the operational information. Methods of improving efficiency of ground operations were assessed and technology elements that could reduce cost identified. Emphasis is on: (1) specific technology items and (2) management approaches required to develop and support efficient ground operations. Prime study results are to be recommendations on how to achieve more efficient operations and identification of existing or new technology that would make vehicle processing in both the current program and future programs more efficient and, therefore, less costly.

  10. Study on eco-efficiency of industrial parks in China based on data envelopment analysis.

    PubMed

    Fan, Yupeng; Bai, Bingyang; Qiao, Qi; Kang, Peng; Zhang, Yue; Guo, Jing

    2017-05-01

    China's industrial parks have been playing a crucial role on driving regional economy development, but also been posing threats to local environment due to intensive resource consumption and waste emission. Chinese government facilitated eco-industrial development of industrial park, aiming to output more with less environmental burden. In our study, the eco-efficiency levels of 40 Chinese industrial parks in 2012 were assessed and ranked by Data Envelopment Analysis (DEA). This paper applied indicators relevant to resource, economy, and environment from industrial parks which can well reflect the characteristics of eco-efficiency conforming to the concept of sustainability. This paper introduced how to adjust less sustainable parks to be more sustainable according to the DEA results. The roles of industrial added value per capita, industrial structure, environmental policy and development scale as influence factors of eco-efficiency were discussed. The results show that large differences exist in the eco-efficiency of different industrial parks. It is shown that 20% of the parks are relatively efficient. 47% of the study parks being inefficient in terms of scale efficiency show decreasing returns to scale. Policy implementations for the management of industrial parks were also discussed based on the results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Technical efficiency analysis for oilseed sunflower farms: a case study in Erzurum, Turkey.

    PubMed

    Külekçi, Murat

    2010-07-01

    The main purpose of this study was to examine the technical efficiency of farms producing sunflower in Erzurum, Turkey and to identify factors that might be causing inefficiency. Stochastic frontier analysis was used to measure technical efficiency. One hundred and seventeen randomly selected farms were interviewed for farm-level data in the 2004-2005 production period. Results revealed that the mean technical efficiency for the sunflower farms, estimated by the stochastic production frontier, is 64%. At full technical efficiency, on average, the farmers could reduce their inputs by around 56% without reducing their sunflower production, simply by improving technical efficiency. In the inefficiency model the parameter estimates showed that older farmers, higher level of farmer's education, more experienced farmers, larger farm size and higher information score resulted in lower technical inefficiency, while bigger family size and more credit usage resulted in higher technical inefficiency. This study proposes strategies such as providing better extension services and farmer-training programmes, including more educated people in sunflower farming and also expanding the sunflower-growing area through provision of adequate facilities in order to increase technical efficiency.

  12. Integrated power sector efficiency analysis: A case study of Costa Rica

    SciTech Connect

    Waddle, D.B.; MacDonald, J.M.

    1990-03-01

    In an effort to analyze and document the potential for power sector efficiency improvements from generation to end-use, the Agency for International Development and the Government of Costa Rica are jointly conducting an integrated power sector efficiency analysis. Potential for energy and cost savings in power plants, transmission and distribution, and demand-side management programs are being evaluated. The product of this study will be an integrated investment plan for the Instituto Costarricense de Electricidad, incorporating both supply and demand side investment options. This paper presents the methodology employed in the study, as well as preliminary estimates of the results of the study. 14 refs., 2 figs., 5 tabs.

  13. The Effect of Curriculum for Developing Efficient Studying Skills on Academic Achievements and Studying Skills of Learners

    ERIC Educational Resources Information Center

    Demir, Semra; Kilinc, Mehmet; Dogan, Ali

    2012-01-01

    Purpose of this study is to examine the effect of "Development of Efficient Studying Skills Curriculum" on academic achievements and studying skills of 7th grade primary school students. In this study, pre-test post-test from experiment models and semi-experimental model with control group were preferred. The reason for the preference is…

  14. Technical efficiency of public district hospitals and health centres in Ghana: a pilot study

    PubMed Central

    Osei, Daniel; d'Almeida, Selassi; George, Melvill O; Kirigia, Joses M; Mensah, Ayayi Omar; Kainyu, Lenity H

    2005-01-01

    Background The Government of Ghana has been implementing various health sector reforms (e.g. user fees in public health facilities, decentralization, sector-wide approaches to donor coordination) in a bid to improve efficiency in health care. However, to date, except for the pilot study reported in this paper, no attempt has been made to make an estimate of the efficiency of hospitals and/or health centres in Ghana. The objectives of this study, based on data collected in 2000, were: (i) to estimate the relative technical efficiency (TE) and scale efficiency (SE) of a sample of public hospitals and health centres in Ghana; and (ii) to demonstrate policy implications for health sector policy-makers. Methods The Data Envelopment Analysis (DEA) approach was used to estimate the efficiency of 17 district hospitals and 17 health centres. This was an exploratory study. Results Eight (47%) hospitals were technically inefficient, with an average TE score of 61% and a standard deviation (STD) of 12%. Ten (59%) hospitals were scale inefficient, manifesting an average SE of 81% (STD = 25%). Out of the 17 health centres, 3 (18%) were technically inefficient, with a mean TE score of 49% (STD = 27%). Eight health centres (47%) were scale inefficient, with an average SE score of 84% (STD = 16%). Conclusion This pilot study demonstrated to policy-makers the versatility of DEA in measuring inefficiencies among individual facilities and inputs. There is a need for the Planning and Budgeting Unit of the Ghana Health Services to continually monitor the productivity growth, allocative efficiency and technical efficiency of all its health facilities (hospitals and health centres) in the course of the implementation of health sector reforms. PMID:16188021

  15. Efficient panel designs for longitudinal recurrent event studies recording panel counts.

    PubMed

    Juarez-Colunga, Elizabeth; Dean, C B; Balshaw, Robert

    2014-04-01

    Many clinical trials are designed to study outcome measures recorded as the number of events occurring during specific intervals, called panel data. In such data, the intervals are specified by a planned set of follow-up times. As the collection of panel data results in a partial loss of information relative to a record of the actual event times, it is important to gain a thorough understanding of the impact of panel study designs on the efficiency of the estimates of treatment effects and covariates. This understanding can then be used as a base from which to formulate appropriate designs by layering in other concerns, e.g. clinical constraints, or other practical considerations. We compare the efficiency of the analysis of panel data with respect to the analysis of data recorded precisely as times of recurrences, and articulate conditions for efficient panel designs where the focus is on estimation of a treatment effect when adjusting for other covariates. We build from the efficiency comparisons to optimize the design of panel follow-up times. We model the recurrent intensity through the common proportional intensity framework, with the treatment effect modeled flexibly as piecewise constant over panels, or groups of panels. We provide some important considerations for the design of efficient panel studies, and illustrate the methods through analysis of designs of studies of adenomas.

  16. A Fundamental Study for Efficient Implementaion of Online Collaborative Activities in Large-Scale Classes

    ERIC Educational Resources Information Center

    Matsuba, Ryuichi; Suzuki, Yusei; Kubota, Shin-Ichiro; Miyazaki, Makoto

    2015-01-01

    We study tactics for writing skills development through cross-disciplinary learning in online large-scale classes, and particularly are interested in implementation of online collaborative activities such as peer reviewing of writing. The goal of our study is to carry out collaborative works efficiently via online effectively in large-scale…

  17. Human Resource Management Strategies and Teacher's Efficiency within Schools: A Co-Relational Study

    ERIC Educational Resources Information Center

    Hashmi, Kiran

    2014-01-01

    The aim of the paper is to study Human Resource Management and Development (HRMD) strategies and their effect on teachers' efficiency within the Catholic Board of Education (CBE) schools of Pakistan whose teachers are graduates in educational leadership courses from a private teacher education institutes in Karachi. The study endeavored to build a…

  18. Product lifetime, energy efficiency and climate change: A case study of air conditioners in Japan.

    PubMed

    Nishijima, Daisuke

    2016-10-01

    This study proposed a modelling technique for estimating life-cycle CO2 emissions of durable goods by considering changes in product lifetime and energy efficiency. The stock and flow of durable goods was modelled by Weibull lifetime distributions and the trend in annual energy efficiency (i.e., annual electricity consumption) of an "average" durable good was formulated as a reverse logistic curve including a technologically critical value (i.e., limit energy efficiency) with respect to time. I found that when the average product lifetime is reduced, there is a trade-off between the reduction in emissions during product use (use phase), due to the additional purchases of new, more energy-efficient air conditioners, and the increase in emissions arising from the additional production of new air conditioners stimulated by the reduction of the average product lifetime. A scenario analysis focused on residential air conditioners in Japan during 1972-2013 showed that for a reduction of average lifetime of 1 year, if the air conditioner energy efficiency limit can be improved by 1.4% from the estimated current efficiency level, then CO2 emissions can be reduced by approximately the same amount as for an extension of average product lifetime of 1 year.

  19. On the efficiency of electrical submersible pumps equipped with variable frequency drives: A field study

    SciTech Connect

    Patterson, M.M.

    1996-02-01

    A field study was conducted on 18 electrical-submersible-pump- (ESP-) equipped wells operating in the Williston basin. Fifteen of these wells were run with variable frequency drives (VFD`s). The purpose of the study was to determine the efficiency and operating characteristics of ESP`s operating with VFD`s and compare them to those without. Voltage, current, power, and frequency were measured at the drive input, the drive output, and ESP input. Production data were recorded and power and efficiency were calculated at all measurement locations and compared to published data.

  20. [ACEEE summer study on energy efficiency in buildings]. Final technical report

    SciTech Connect

    Not Available

    1990-12-31

    The ACEEE Summer Study is a biennial conference that aims to bring together the foremost researchers, practitioners and policy makers involved in research on energy efficiency in buildings. The 1990 Summer Study had the objective to facilitate the exchange of research and implementation results and encourage the advancement of knowledge in the field of energy efficiency in buildings. The research papers presented at the conference published and distributed. Two hundred seventy two papers were presented. These individual papers, published in ten volumes, have been processed separately for the Energy Data Base.

  1. Validity Study in Multidimensional Latent Space and Efficient Computerized Adaptive Testing

    DTIC Science & Technology

    1990-09-01

    IONR/FINAL REPOR Q IITI r-- nI VALIDITY STUDY IN MULTIDIMENSIONAL LATENT SPACE I 4 AND EFFICIENT COMPUTERIZED1 " ADAPTIVE TESTING CM 3 FUMIKO...study in multidimensional latent space and efficient computerized adaptive testing 12 PERSONAL AUITHOR(S) Fumiko Samejima, Ph.D. 1 3a TYPE OF REPORT 13b...17 COSATI CODES I8 SUBJECT TERMS (Continue on reverse if necessary ad identify oy block numtoer) FIELD GROUP SUB-GROUP Latent Trait Models, Mental Test

  2. The IAEA Radiotracer Biodistribution Template - A community resource for supporting the standardization and reporting of radionuclide pre-dosimetry data.

    PubMed

    Kesner, Adam Leon; Poli, Gian Luca; Beykan, Seval; Lassmann, Michael

    2017-09-15

    Radionuclide absorbed-dose dosimetry is an active area of development and has the potential to positively impact molecular radiotherapies. At present, many of the operations required to perform dosimetry calculations are unstandardized and unestablished. While the current methodology allows reasonable dosimetry estimates to be derived and published, it can be difficult to understand, and reproduce, each others' work. To help alleviate this we have identified the collection of biodistribution information as a key step in all internal dosimetry calculations, and present a template that can be used to standardize its documentation and reporting. A generalized biodistribution template entitled the IAEA Radiotracer Biodistribution Template (IAEA RaBiT) has been built and distributed for users performing biodistribution measurements in the community. The template enables robust recording of dosimetry-relevant information through standardization of details and their format. It has been designed to be simple and easy to use, and establish a structured recording of a common reference point in dosimetry operations - biodistribution data documentation. Improved documentation procedures may benefit organization of in house data, or be used to disseminate details throughout the community - for example to supplement dosimetry related publications. The standard format information may also enable the creation of new dosimetry related tools and protocols and support robust population databases. As dosimetry in nuclear medicine becomes more routinely applied in clinical applications, we need to develop the infrastructure for robustly handling large amounts of these data. Our IAEA RaBiT can be used as a standard format structure for data collection, organization, and dissemination. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  3. Improved Most-Probable-Number Method To Detect Sulfate-Reducing Bacteria with Natural Media and a Radiotracer

    PubMed Central

    Vester, Flemming; Ingvorsen, Kjeld

    1998-01-01

    A greatly improved most-probable-number (MPN) method for selective enumeration of sulfate-reducing bacteria (SRB) is described. The method is based on the use of natural media and radiolabeled sulfate (35SO42−). The natural media used consisted of anaerobically prepared sterilized sludge or sediment slurries obtained from sampling sites. The densities of SRB in sediment samples from Kysing Fjord (Denmark) and activated sludge were determined by using a normal MPN (N-MPN) method with synthetic cultivation media and a tracer MPN (T-MPN) method with natural media. The T-MPN method with natural media always yielded significantly higher (100- to 1,000-fold-higher) MPN values than the N-MPN method with synthetic media. The recovery of SRB from environmental samples was investigated by simultaneously measuring sulfate reduction rates (by a 35S-radiotracer method) and bacterial counts by using the T-MPN and N-MPN methods, respectively. When bacterial numbers estimated by the T-MPN method with natural media were used, specific sulfate reduction rates (qSO42−) of 10−14 to 10−13 mol of SO42− cell−1 day−1 were calculated, which is within the range of qSO42− values previously reported for pure cultures of SRB (10−15 to 10−14 mol of SO42− cell−1 day−1). qSO42− values calculated from N-MPN values obtained with synthetic media were several orders of magnitude higher (2 × 10−10 to 7 × 10−10 mol of SO42− cell−1 day−1), showing that viable counts of SRB were seriously underestimated when standard enumeration media were used. Our results demonstrate that the use of natural media results in significant improvements in estimates of the true numbers of SRB in environmental samples. PMID:9572939

  4. Financial Analysis of Incentive Mechanisms to Promote Energy Efficiency: Case Study of a Prototypical Southwest Utility

    SciTech Connect

    Cappers, Peter; Goldman, Charles; Chait, Michele; Edgar, George; Schlegel, Jeff; Shirley, Wayne

    2009-03-04

    Many state regulatory commissions and policymakers want utilities to aggressively pursue energy efficiency as a strategy to mitigate demand and energy growth, diversify the resource mix, and provide an alternative to building new, costly generation. However, as the National Action Plan for Energy Efficiency (NAPEE 2007) points out, many utilities continue to shy away from aggressively expanding their energy efficiency efforts when their shareholder's fundamental financial interests are placed at risk by doing so. Thus, there is increased interest in developing effective ratemaking and policy approaches that address utility disincentives to pursue energy efficiency or lack of incentives for more aggressive energy efficiency efforts. New regulatory initiatives to promote increased utility energy efficiency efforts also affect the interests of consumers. Ratepayers and their advocates are concerned with issues of fairness, impacts on rates, and total consumer costs. From the perspective of energy efficiency advocates, the quid pro quo for utility shareholder incentives is the obligation to acquire all, or nearly all, achievable cost-effective energy efficiency. A key issue for state regulators and policymakers is how to maximize the cost-effective energy efficiency savings attained while achieving an equitable sharing of benefits, costs and risks among the various stakeholders. In this study, we modeled a prototypical vertically-integrated electric investor-owned utility in the southwestern US that is considering implementing several energy efficiency portfolios. We analyze the impact of these energy efficiency portfolios on utility shareholders and ratepayers as well as the incremental effect on each party when lost fixed cost recovery and/or utility shareholder incentive mechanisms are implemented. A primary goal of our quantitative modeling is to provide regulators and policymakers with an analytic framework and tools that assess the financial impacts of

  5. Study of the photo-detection efficiency of FBK High-Density silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Zappalà, G.; Acerbi, F.; Ferri, A.; Gola, A.; Paternoster, G.; Regazzoni, V.; Zorzi, N.; Piemonte, C.

    2016-11-01

    This work presents a study of the factors contributing to the Photo-Detection Efficiency of Silicon Photomultipliers (SiPMs): Quantum Efficiency, Triggering Probability and Fill Factor. Two different SiPM High-Density technologies are tested, NUV-HD, based on n-on-p junction, and RGB-HD, based on p-on-n junction, developed at FBK, Trento. The quantum efficiency was measured on photodiodes produced along with the SiPMs. The triggering probability, as a function of wavelength and bias voltage, was measured on circular Single Photon Avalanche Diodes (SPADs) with 100% fill factor. Square SPADs, having the same layout of single SiPM cells, were studied to measure the effective fill factor and compare it to the nominal value. The comparison of the circular and square SPADs allows to get the transition region size between the effective active area of the cell and the one defined by the layout.

  6. Variation in efficiency of parallel algorithms. [for study of stiffness matrices in planar trusses

    NASA Technical Reports Server (NTRS)

    Hayashi, A.; Melosh, R. J.; Utku, S.; Salama, M.

    1985-01-01

    The present study has the objective to investigate some iterative parallel-processor linear equation solving algorithms with respect to efficiency for analyses of typical linear engineering systems. Attention is given to a set of n linear equations, Ku = p, where K = an n x n positive definite, sparsely populated, symmetric matrix, u = an n x 1 vector of unknown responses, and p = an n x 1 vector of prescribed constants. This study is concerned with a hybrid method in which iteration is used to solve the problem, while a direct method is used on the local processor level. Variations in the efficiency of parallel algorithms are explored. Measures of the efficiency are based on computer experiments regarding the algorithms. For all the algorithms, the wall clock time is found to decrease as the number of processors increases.

  7. Evaluation of [(18) F]BR420 and [(18) F]BR351 as radiotracers for MMP-9 imaging in colorectal cancer.

    PubMed

    Vazquez, Naiara; Missault, Stephan; Vangestel, Christel; Deleye, Steven; Thomae, David; Van der Veken, Pieter; Augustyns, Koen; Staelens, Steven; Dedeurwaerdere, Stefanie; Wyffels, Leonie

    2017-01-01

    MMP-9 is a zinc-dependent endopeptidase that is involved in the proteolytic degradation of the extracellular matrix and plays an important role in cancer migration, invasion, and metastasis. The aim of this study was to evaluate the potential of MMP-tracers [(18) F]BR420 and [(18) F]BR351 for MMP-9 imaging in a colorectal cancer xenograft model. [(18) F]BR420 and [(18) F]BR351 were synthesized using an automated synthesis module. For [(18) F]BR420, a novel and improved radiosynthesis was developed. Plasma stability and MMP-9-targeting capacity of both radiotracers was compared in the Colo205 colorectal cancer model. MMP-9 and MMP-2 expression levels in the tumors were evaluated by immunohistochemistry and in situ zymography. μPET imaging as well as ex vivo biodistribution revealed a higher tumor uptake for [(18) F]BR420 (3.15% ± 0.03% ID/g vs 0.94% ± 0.18% ID/g for [(18) F]BR351 at 2 hours pi) but slower blood clearance compared with [(18) F]BR351. [(18) F]BR351 was quickly metabolized in plasma with 20.28% ± 5.41% of intact tracer remaining at 15 minutes postinjection (PI). By contrast, [(18) F]BR420 displayed a higher metabolic stability with >86% intact tracer remaining at 2 hours PI. Immunohistochemistry revealed the presence of MMP-9 and MMP-2 in the tumor tissue, which was confirmed by in situ zymography. However, an autoradiography analysis of tracer distribution in the tumors did not correlate with MMP-9 expression. [(18) F]BR420 displayed a higher tumor uptake and higher stability compared with [(18) F]BR351 but a low tumor-to-blood ratio and discrepancy between tracer distribution and MMP-9 immunohistochemistry. Therefore, both tracers will not be usefulness for MMP-9 imaging in colorectal cancer.

  8. Glu-Ureido-Based Inhibitors of Prostate-Specific Membrane Antigen: Lessons Learned During the Development of a Novel Class of Low-Molecular-Weight Theranostic Radiotracers.

    PubMed

    Kopka, Klaus; Benešová, Martina; Bařinka, Cyril; Haberkorn, Uwe; Babich, John

    2017-09-01

    In recent years, several radioligands targeting prostate-specific membrane antigen (PSMA) have been clinically introduced as a new class of theranostic radiopharmaceuticals for the treatment of prostate cancer (PC). In the second decade of the 21(st) century, a new era in nuclear medicine was initiated by the clinical introduction of small-molecule PSMA inhibitor radioligands, 40 y after the clinical introduction of (18)F-FDG. Because of the high incidence and mortality of PC, the new PSMA radioligands have already had a remarkable impact on the clinical management of PC. For the continuing clinical development and long-term success of theranostic agents, designing modern prospective clinical trials in theranostic nuclear medicine is essential. First-in-human studies with PSMA radioligands derived from small-molecule PSMA inhibitors showed highly sensitive imaging of PSMA-positive PC by means of PET and SPECT as well as a dramatic response of metastatic castration-resistant PC after PSMA radioligand therapy. This tremendous success logically led to the initiation of prospective clinical trials with several PSMA radioligands. Meanwhile, MIP-1404, PSMA-11, 2-(3-{1-carboxy-5-[(6-fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (DCFPyL), PSMA-617, PSMA-1007, and others have entered or will enter prospective clinical trials soon in several countries. The significance becomes apparent by, for example, the considerable increase in the number of publications about PSMA-targeted PET imaging from 2013 to 2016 (e.g., a search of the Web of Science for "PSMA" AND "PET" found only 19 publications in 2013 but 218 in 2016). Closer examination of the initial success of PC treatment with PSMA inhibitor radiotracers leads to several questions from the basic research perspective as well as from the perspective of clinical demands: What lessons have been learned regarding the design of PSMA radioligands that have already been developed? Has an acceptable compromise

  9. Modeling radiotracers in sediments: Comparison with observations in Lakes Huron and Michigan

    NASA Astrophysics Data System (ADS)

    Christensen, Erik R.; Bhunia, Prasanta K.

    1986-07-01

    A comprehensive model for the activity of radionuclides in sediments is presented. The model is based on the advection-diffusion equations for sediment solids and a radioactive tracer. Mixing, caused by deposit feeders, is taken into account by a half-Gaussian (HG), integrated Gaussian (IG), or exponential (EX) diffusion coefficient with a maximum value D0 at the sediment-water interface and an effective mixing depth m, where m = σ(HG), zm (IG), or a (EX). Compaction is described by an exponential bulk sediment density. The differential equations are solved by finite differences, in particular, the Crank-Nicolson method for the time-dependent case (Cs-137). Estimation of the mixing parameters D0 and m is carried out efficiently by minimizing chi-square for measured and calculated steady state Pb-210 activities. The derived mixing depths of zm = 4.6 ± 0.1 cm (station 14) and a = 0.8 ± 0.1 cm (station 18) for the cores from Lake Huron are in good agreement with the organism distributions. The corresponding D0 values are 12 ± 2 and 1.5 ± 0.5 cm2/yr, respectively, where the latter number is lower than a previous lower limit estimate (≥ 3.3 cm2/yr), based on 1974 data. These diffusion coefficients are in excellent agreement with those inferred from the densities of Pontoporeia and tubificid oligochaetes (9.3 and 1.6 cm2/yr, respectively). Compared with southern Lake Michigan, there appears to be less sediment focusing in northern Lake Michigan, where the ratios of measured to atmospheric Cs-137 inventories have an average value of 0.89 and range from 0.32 to 1.41 for six cores from the deep basin. When these ratios are used to correct the Pb-210 fluxes, we obtain an atmospheric Pb-210 flux of 0.99 ± 0.06 dpm/cm2/yr. Because of its more realistic activity profiles, we consider the present model to be generally better than previous models.

  10. Internal radiation dosimetry of orally administered radiotracers for the assessment of gastrointestinal motility.

    PubMed

    Yeong, Chai-Hong; Ng, Kwan-Hoong; Abdullah, Basri Johan Jeet; Chung, Lip-Yong; Goh, Khean-Lee; Perkins, Alan Christopher

    2014-12-01

    Radionuclide imaging using (111)In, (99m)Tc and (153)Sm is commonly undertaken for the clinical investigation of gastric emptying, intestinal motility and whole gut transit. However the documented evidence concerning internal radiation dosimetry for such studies is not readily available. This communication documents the internal radiation dosimetry for whole gastrointestinal transit studies using (111)In, (99m)Tc and (153)Sm labeled formulations. The findings were compared to the diagnostic reference levels recommended by the United Kingdom Administration of Radioactive Substances Advisory Committee, for gastrointestinal transit studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Technical and scale efficiency of public community hospitals in Eritrea: an exploratory study

    PubMed Central

    2013-01-01

    Background Eritrean gross national income of Int$610 per capita is lower than the average for Africa (Int$1620) and considerably lower than the global average (Int$6977). It is therefore imperative that the country’s resources, including those specifically allocated to the health sector, are put to optimal use. The objectives of this study were (a) to estimate the relative technical and scale efficiency of public secondary level community hospitals in Eritrea, based on data generated in 2007, (b) to estimate the magnitudes of output increases and/or input reductions that would have been required to make relatively inefficient hospitals more efficient, and (c) to estimate using Tobit regression analysis the impact of institutional and contextual/environmental variables on hospital inefficiencies. Methods A two-stage Data Envelopment Analysis (DEA) method is used to estimate efficiency of hospitals and to explain the inefficiencies. In the first stage, the efficient frontier and the hospital-level efficiency scores are first estimated using DEA. In the second stage, the estimated DEA efficiency scores are regressed on some institutional and contextual/environmental variables using a Tobit model. In 2007 there were a total of 20 secondary public community hospitals in Eritrea, nineteen of which generated data that could be included in the study. The input and output data were obtained from the Ministry of Health (MOH) annual health service activity report of 2007. Since our study employs data that are five years old, the results are not meant to uncritically inform current decision-making processes, but rather to illustrate the potential value of such efficiency analyses. Results The key findings were as follows: (i) the average constant returns to scale technical efficiency score was 90.3%; (ii) the average variable returns to scale technical efficiency score was 96.9%; and (iii) the average scale efficiency score was 93.3%. In 2007, the inefficient hospitals could

  12. Preclinical evaluation of 99mTc(CO)3-aspartic-N-monoacetic acid, 99mTc(CO)3(ASMA), a new renal radiotracer with pharmacokinetic properties comparable to 131I-OIH

    PubMed Central

    Lipowska, Malgorzata; Klenc, Jeffrey; Marzilli, Luigi G.; Taylor, Andrew T.

    2014-01-01

    In an ongoing effort to develop a renal tracer with pharmacokinetic properties comparable to PAH and superior to those of both 99mTc-MAG3 and 131I-OIH, we evaluated a new renal tricarbonyl radiotracer based on the aspartic-N-monoacetic acid ligand, 99mTc(CO)3(ASMA). The ASMA ligand features two carboxyl groups and an amine function for the coordination of the {99mTc(CO)3}+ core as well as a dangling carboxylate to facilitate rapid renal clearance. Methods rac-ASMA and L-ASMA were labeled with a 99mTc-tricarbonyl precursor and radiochemical purity of the labeled products was determined by HPLC. Using 131I-OIH as an internal control, we evaluated biodistribution in normal rats with 99mTc(CO)3(ASMA) isomers and in rats with renal pedicle ligation with 99mTc(CO)3(rac-ASMA). Clearance studies were conducted in 4 additional rats. In vitro radiotracer stability was determined in PBS buffer pH 7.4 and in challenge studies with cysteine and histidine. 99mTc(CO)3(ASMA) metabolites in urine were analyzed by HPLC. Results Both 99mTc(CO)3(ASMA) preparations had > 99% radiochemical purity and were stable in PBS buffer pH 7.4 for 24 h. Challenge studies on both revealed no significant displacement of the ligand. In normal rats, % injected dose in urine at 10 and 60 min for both preparations averaged 103% and 106% that of 131I-OIH, respectively. The renal clearances of 99mTc(CO)3(rac-ASMA) and 131I-OIH were comparable (P = 0.48). The tracer was excreted unchanged in the urine, proving its in vivo stability. In pedicle-ligated rats, 99mTc(CO)3(rac-ASMA) had less excretion into the bowel (P < 0.05) and was better retained in the blood (P < 0.05) than 131I-OIH. Conclusion Both 99mTc(CO)3(ASMA) complexes have pharmacokinetic properties in rats comparable to or superior to those of 131I-OIH, and human studies are warranted for their further evaluation. PMID:22717977

  13. Greens, suits, and bureaucrats: A sociological study of dynamic organizational relationships in energy efficient appliance policy

    NASA Astrophysics Data System (ADS)

    Shwom-Evelich, Rachael Leah

    In this dissertation I develop an approach to understanding dynamic organizational relations and the processes of environmental degradation and reform. To do this, I draw on environmental and organizational sociology to inform an empirical study of interorganizational relationships in defining and promoting energy efficient appliances in the United States (US). The dissertation follows a three paper approach which involves (a) an overall introduction to the substantive issue of appliance energy efficiency in the US; (b) producing three separate and stand alone articles of publishable quality to be submitted to professional journals; and (c) an overall conclusion. The three articles are as follows: (1) a synthetic literature review identifying five lessons that organizational sociology and environmental sociology can learn from each other to advance our sociological understanding of organizations, energy issues, and climate change (2) a qualitative case study of the changing relationships between business, government and environmental and energy advocacy organizations around mandatory appliance efficiency standards supporting the development of a context-dependent theory of ecological modernization and treadmill of production theories in environmental sociology and (3) a network analysis of public government, business and energy efficiency advocate's interorganizational relationships and its influence on subsequent organizational behaviors in the appliance energy efficiency field. The second and third articles are based on extensive archival research on organizational negotiations of public record over defining energy efficient appliances in both regulatory and voluntary settings. Finally I will provide an overall conclusion that brings together the most significant findings of each individual article in anticipation of a synthetic approach to the study of organizations in environmental reform.

  14. A generally adoptable radiotracing method for tracking carbon nanotubes in animals

    NASA Astrophysics Data System (ADS)

    Deng, Xiaoyong; Yang, Shengtao; Nie, Haiyu; Wang, Haifang; Liu, Yuanfang

    2008-02-01

    Carbon nanotube (CNT) mediated drug delivery systems have currently aroused a great deal of interest. Such delivery systems for drugs, proteins and genes have been preliminarily studied using cellular and animal models. For the further study of the pharmacokinetics and related biological behaviours of CNTs in vivo, a fast and convenient tracing method is particularly demanded. In this paper, we developed a generally adoptable tracing method for the biodistribution study of functionalized CNTs in vivo. Taurine covalently functionalized multi-walled carbon nanotubes (tau-MWNTs) and Tween-80 wrapped MWNTs (Tween-MWNTs) were labelled with 125I, and then their distribution in mice was determined. It is interesting that Tween-80 can reduce the RES uptake of MWNTs remarkably. The resulting distribution of 125I-tau-MWNTs was very consistent with that using 14C-taurine-MWNTs as the CNTs tracer, which means the easy 125I labelling method is reliable and effective.

  15. Evaluation of the In Vivo and Ex Vivo Binding of Novel BC1 Cannabinoid Receptor Radiotracers

    SciTech Connect

    Miller, A.; Gatley, J.; Gifford, A.

    2002-01-01

    The primary active ingredient of marijuana, 9-tetrahydrocannabinol, exerts its psychoactive effects by binding to cannabinoid CB1 receptors. These receptors are found throughout the brain with high concentrations in the hippocampus and cerebellum. The current study was conducted to evaluate the binding of a newly developed putative cannabinoid antagonist, AM630, and a classical cannabinoid 8-tetrahydrocannabinol as potential PET and/or SPECT imaging agents for brain CB1 receptors. For both of these ligands in vivo and ex vivo studies in mice were conducted. AM630 showed good overall brain uptake (as measure by %IA/g) and a moderately rapid clearance from the brain with a half-clearance time of approximately 30 minutes. However, AM630 did not show selective binding to CB1 cannabinoid receptors. Ex vivo autoradiography supported the lack of selective binding seen in the in vivo study. Similar to AM630, 8-tetrahydrocanibol also failed to show selective binding to CB1 receptor rich brain areas. The 8-tetrahydrocanibol showed moderate overall brain uptake and relatively slow brain clearance as compared to AM630. Further studies were done with AM2233, a cannabinoid ligand with a similar structure as AM630. These studies were done to develop an ex vivo binding assay to quantify the displacement of [131I]AM2233 binding by other ligands in Swiss-Webster and CB1 receptor knockout mice. By developing this assay we hoped to determine the identity of an unknown binding site for AM2233 present in the hippocampus of CB1 knockout mice. Using an approach based on incubation of brain slices prepared from mice given intravenous [131I]AM2233 in either the presence or absence of AM2233 (unlabelled) it was possible to demonstrate a significant AM2233-displacable binding in the Swiss-Webster mice. Future studies will determine if this assay is appropriate for identifying the unknown binding site for AM2233 in the CB1 knockout mice.

  16. Experimental study of efficiency of solar panel by phase change material cooling

    NASA Astrophysics Data System (ADS)

    Wei, Nicholas Tan Jian; Nan, Wong Jian; Guiping, Cheng

    2017-07-01

    The dependence of efficiency of photovoltaic panels on their temperature during operation is a major concern for developers and users. In this paper, a phase change material (PCM) cooling system was designed for a 60W mono-crystalline solar panel. Tealights candle was selected as the cooling medium. The solar irradiance was recorded using Kipp & Zonen CMP3 pyranometer and Meteon data logger. Temperature distribution on the surface of solar panel, output voltage and output current of solar panel were measured. The average irradiance throughout data collection was found to be 705W/m2 and highest irradiance was 1100 W/m2. The average solar panel temperature was 43.6°C and a maximum temperature of 53°C was at the center of solar panel. Results showed that average power output and efficiency of the solar panel were 44.4W and 15%, respectively. It was found that the higher the solar irradiance, the lower the efficiency of solar panel and the higher the temperature and power output of solar panel. This is due to the fact that high irradiance results in high power input and high solar panel temperature. But high PV panel temperature reduces its power output. Therefore, the increase of power input outweighs that of power output, which leads to the decrease of efficiency of solar panel with the increase of solar irradiance. Compared with solar panel without cooling, the power output and efficiency of solar panel did not increase with PCM cooling. It indicates that Tealights candle as PCM cooling is not efficient in improving the efficiency of solar panel in this study.

  17. Tracking Our Success: How TAFE Institutes Measure Their Effectiveness and Efficiency--Case Studies. Support Document

    ERIC Educational Resources Information Center

    Misko, Josie; Wynes, Sian Halliday

    2009-01-01

    This report is the support document to "Tracking Our Success: How TAFE Institutes Measure Their Effectiveness and Efficiency". It comprises reports on each of the nine technical and further education (TAFE) institutes that have taken part in the study. Information was collected via in-depth interviews with chief executive officers and…

  18. Studies of oxygen-related and carbon-related defects in high-efficiency solar cells

    NASA Technical Reports Server (NTRS)

    Corbett, J. W.

    1985-01-01

    Oxygen and carbon related defects in silicon, particularly as related to high-efficiency silicon solar cells were studied. A summary of oxygen processes in silicon versus process temperature was shown along with experimental results. The anamolous diffusion of oxygen was explained by the dissociation of the center allowing O sub i to move through the lattices.

  19. A Study on the Learning Efficiency of Multimedia-Presented, Computer-Based Science Information

    ERIC Educational Resources Information Center

    Guan, Ying-Hua

    2009-01-01

    This study investigated the effects of multimedia presentations on the efficiency of learning scientific information (i.e. information on basic anatomy of human brains and their functions, the definition of cognitive psychology, and the structure of human memory). Experiment 1 investigated whether the modality effect could be observed when the…

  20. A parametric study for high-efficiency gas-liquid separator design

    NASA Astrophysics Data System (ADS)

    Nagdewe, S.; Kwoon, J. K.; Kim, H. D.; Kim, D. S.; Kwak, K. M.; Setoguchi, Toshiaki

    2008-09-01

    A gas liquid centrifugal separator is widely used in industry on account of its simple geometry and little maintenance. These separators have considerable advantages over filters, scrubbers or precipitators in term of compact design, lower pressure drop and higher capacity. A gas liquid centrifugal separator is a device that utilizes centrifugal forces and low pressure caused by rotational motion to separate liquid from gas by density differences. Efficient and reliable separation is required for the optimum operation. These separators are often operated at less than peak efficiency due to the entrainment of separated liquid through an outlet pipe which is closely associated with the very complicated flow phenomena involved. Design parameters such as length of the separation space, vane exit angle, inlet to outlet diameter ratio, models for separation efficiency and pressure drop as a function of physical dimensions are not available in literature. This leaves the designer with very little to go on except known designs and experimentation. The aim of present study is to perform a parametric study to get higher efficiency for gas-liquid separator. A parametric study has been carried out with the help of CFD tools to analyze a separation performance of a centrifugal separator by varying the length of separator space. The best design parameters are analyzed based upon obtained results, tangential velocities, vortices, total pressure losses. From the present study several attempts are made to improve the performance of conventional centrifugal separators.

  1. A Study on the Learning Efficiency of Multimedia-Presented, Computer-Based Science Information

    ERIC Educational Resources Information Center

    Guan, Ying-Hua

    2009-01-01

    This study investigated the effects of multimedia presentations on the efficiency of learning scientific information (i.e. information on basic anatomy of human brains and their functions, the definition of cognitive psychology, and the structure of human memory). Experiment 1 investigated whether the modality effect could be observed when the…

  2. Expectation-Based Efficiency and Quality Improvements in Research Administration: Multi-Institutional Case Studies

    ERIC Educational Resources Information Center

    Saha, Dhanonjoy C.; Ahmed, Abrar; Hanumandla, Shailaja

    2011-01-01

    Conventional wisdom may support the presumed notion that higher expectations increase efficiency and improve quality. However, this claim may only be validated when workers are equipped with appropriate tools, training, and a conducive work environment. This study implements various interventions, observes outcomes, and analyzes data collected in…

  3. Study on Providing Professors with Efficient Service Based on Time Management Strategy

    ERIC Educational Resources Information Center

    Li, Chunlin; Liu, Mengchao; Wang, Yining

    2016-01-01

    Time management is the study to use time scientifically by deploying skills, techniques and means, and maximizing time value to help individuals or organizations efficiently complete tasks and achieve goals. University professor as a body is an important force in teaching and research. In order to ensure high-quality teaching, productive research,…

  4. Study of π{sup 0}/γ efficiency using B meson decays in the LHCb experiment

    SciTech Connect

    Govorkova, E.

    2016-12-15

    The reconstruction efficiency of photons and neutral pions is measured using the relative yields of reconstructed B{sup +} → J/ψK{sup *+}(→ K{sup +}π{sup 0}) and B{sup +} → J/ψK{sup +} decays. The efficiency is studied using the data set, corresponding to an integrated luminosity of 3 fb{sup –1}, collected by the LHCb experiment in proton-proton collisions at the centre-of-mass energies of 7 and 8 TeV.

  5. Solubilizing efficiency of different gutta-percha solvents: a comparative study.

    PubMed

    Görduysus, M O; Taşman, F; Tuncer, S; Etikan, I

    1997-09-01

    A study was conducted to comparatively evaluate the efficiency of different solvents for dissolving gutta-percha. Halothane, chloroform, xylene, acetone, isopropyl alcohol, turpentine, oil of mela-leuca and eucalyptol were used as solvents for dissolving standardized gutta-percha discs. Halothane, chloroform and xylene were markedly superior solvents of gutta-percha in comparison with the others. There was no significant difference among the three (p > 0.05). Eucalyptol, turpentine and oil of melaleuca were relatively less efficient. Acetone and isopropyl alcohol did not dissolve gutta-percha, being similar in this respect to distilled water.

  6. Particle balance study for the fueling efficiency in KSTAR experiments 2013

    NASA Astrophysics Data System (ADS)

    Juhn, J.-. W.; Hahn, S. H.; Hong, S. H.; Song, J. I.; Kim, Y. O.; Kim, K. P.; Kim, J. S.

    2014-10-01

    The efficiencies of the fueling system in the KSTAR have been studied for the 2013 experimental results. The absolute amount of injected fuel or deuterium has been calibrated in advance of the main plasma experiments. This includes the primary actuator of fueling, i.e., gas puffing (GP) with piezoelectric valves located on mid-plane, and supersonic molecular beam injector (SMBI). In addition, neutral beam injectors (NBIs) and their base facility chamber also contribute to the amount of fuel injection whenever they are operated. Low fueling efficiency combined with particle loss due to wall retention essentially results in poor performance of density feedback control magnetic fusion devices such as the KSTAR.

  7. A theoretical framework to study potassium utilization efficiency in response to withdrawal of potassium.

    PubMed

    Moriconi, Jorge I; Santa-María, Guillermo E

    2013-11-01

    An important objective of plant research is to improve the efficiency in the utilization of major nutrients, particularly nitrogen, phosphorus, and potassium. Several definitions of internal nutrient utilization efficiency (NUE) have been proposed, but the theoretical consistence of their use has been poorly explored. Here, a non-mechanistic approach was developed to theoretically examine the dynamics of commonly used NUE indicators following complete potassium deprivation. This approach was used to study the sensitivity of NUE indicators to changes in the actual NUE (NUEa) of K(+) in virtual plants. Three empirically based models that differ in the relationship between NUE and the internal K(+) concentration were examined. Frequently used indicators (potassium use efficiency, utilization efficiency, physiological efficiency, and nutrient productivity) and two additional ones introduced here (accumulated productivity and physiological ratio) differed in their capacity to reflect differences in NUEa. They also exhibited large disparities in their temporal variation and in their responsiveness to the concentration of K(+) before the beginning of the deprivation period. According to this analysis, the simultaneous use of several indicators could help to refine plant breeding for high NUE. The data also suggest that a trade off between plant productivity and the time necessary to reduce the concentration of K(+) by half is inherent to the dynamics of plant systems. Finally, it is proposed that for some plant species selection for high NUEa would not always be in conflict with selection for improved relative plant performance in low K(+) environments.

  8. Comparative study of fusion algorithms and implementation of new efficient solution

    NASA Astrophysics Data System (ADS)

    Besrour, Amine; Snoussi, Hichem; Siala, Mohamed; Abdelkefi, Fatma

    2014-05-01

    High Dynamic Range (HDR) imaging has been the subject of significant researches over the past years, the goal of acquiring the best cinema-quality HDR images of fast-moving scenes using an efficient merging algorithm has not yet been achieved. In fact, through the years, many efficient algorithms have been implemented and developed. However, they are not yet efficient since they don't treat all the situations and they have not enough speed to ensure fast HDR image reconstitution. In this paper, we will present a full comparative analyze and study of the available fusion algorithms. Also, we will implement our personal algorithm which can be more optimized and faster than the existed ones. We will also present our investigated algorithm that has the advantage to be more optimized than the existing ones. This merging algorithm is related to our hardware solution allowing us to obtain four pictures with different exposures.

  9. A study of the efficiency of a gas screen on a rough surface

    NASA Astrophysics Data System (ADS)

    Komarov, V. P.; Leontev, A. I.; Okolito, L. A.; Puzach, V. G.

    1982-12-01

    A study of the efficiency of a gas screen generated on a rough surface by injection through a passive porous section shows that the Kutateladze-Leontiev theory (1972) formulated for smooth surfaces can be extended to rough surfaces. The knowledge of the relative friction law and of the velocity profiles is required, however, for each specific rough surface. For the quadratic law of the rough surface resistance, experimental data on friction and velocity profiles are generalized, and a formula for the gas screen efficiency is derived. It is found that for the quadratic law of resistance, the efficiency of a gas screen is independent of the height and spacing of the roughness elements.

  10. A precise study on effects that trigger alkaline hemicellulose extraction efficiency.

    PubMed

    Hutterer, Christian; Schild, Gabriele; Potthast, Antje

    2016-08-01

    The conversion of paper-grade pulps into dissolving pulps requires efficient strategies and process steps to remove low-molecular noncellulosic macromolecules generally known as hemicelluloses. Current strategies include alkaline extractions and enzymatic treatments. This study focused on the evaluation of extraction efficiencies in alkaline extractions of three economically interesting hardwood species: beech (Fagus sylvatica), birch (Betula papyrifera), and eucalyptus (Eucalyptus globulus). Substrate pulps were subjected to alkaline treatments at different temperatures and alkalinities using white liquor as the alkali source, followed by analyses of both pulps and hemicellulose-containing extraction lyes. The extracted hardwood xylans have strong potential as an ingredient in the food and pharmaceutical industries. Subsequent analyses revealed strong dependencies of the extraction efficiencies and molar mass distributions of hemicelluloses on the process variables of temperature and effective alkalinity. The hemicellulose content of the initial pulps, the hardwood species, and the type of applied base played minor roles. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Genome-wide efficient mixed-model analysis for association studies.

    PubMed

    Zhou, Xiang; Stephens, Matthew

    2012-06-17

    Linear mixed models have attracted considerable attention recently as a powerful and effective tool for accounting for population stratification and relatedness in genetic association tests. However, existing methods for exact computation of standard test statistics are computationally impractical for even moderate-sized genome-wide association studies. To address this issue, several approximate methods have been proposed. Here, we present an efficient exact method, which we refer to as genome-wide efficient mixed-model association (GEMMA), that makes approximations unnecessary in many contexts. This method is approximately n times faster than the widely used exact method known as efficient mixed-model association (EMMA), where n is the sample size, making exact genome-wide association analysis computationally practical for large numbers of individuals.

  12. Advances in software for faster procedure and lower radiotracer dose myocardial perfusion imaging.

    PubMed

    Piccinelli, Marina; Garcia, Ernest V

    2015-01-01

    The American Society of Nuclear Cardiology has recently published documents that encourage laboratories to take all the appropriate steps to greatly decrease patient radiation dose and has set the goal of 50% of all myocardial perfusion studies performed with an associated radiation exposure of 9mSv by 2014. In the present work, a description of the major software techniques readily available to shorten procedure time and decrease injected activity is presented. Particularly new reconstruction methods and their ability to include means for resolution recovery and noise regularization are described. The use of these improved reconstruction algorithms results in a consistent reduction in acquisition time, injected activity and consequently in the radiation dose absorbed by the patient. The clinical implications to the use of these techniques are also described in terms of maintained and even improved study quality, accuracy and sensitivity for the detection of heart disease.

  13. Studies of micromorphology and current efficiency of zinc electrodeposited from flowing chloride electrolytes

    SciTech Connect

    Mc Vay, L.; Muller, R.H.; Tobias, C.W.

    1986-05-01

    Results of a study of the micromorphology and current efficiency of zinc electrodeposited from flowing, acidic chloride solutions are reported. The effects of six variables were examined: flow rate, current density, zinc and hydrogen ion concentration, concentrations of nickel, iron and cadmium impurity ions, and the nature of the substrate. The development of micromorphology was studied in-situ by means of videomicrography and ex-situ by means of scanning electron microscopy. This investigation focused on the formation of grooved deposits, which are found under a wide range of deposition conditions. The major conclusions of this study are: the most important variable determining whether grooved deposits form is the interfacial concentration; large protrusions orient themselves parallel to the flow direction with the orientation starting upstream and progressing downstream; large protrusions become ridges due to growth of the highest current density portions of the electrode under mass transport control. The current efficiency was measured using EDTA titration and weight measurements. The fraction of the current taken by zinc deposition increased with zinc concentration, ranging up to 100%, and decreased with pH. The efficiency of zinc deposition was affected by the flow rate and the substrate employed. Impurities lowered the current efficiency.

  14. Single-cell analysis of radiotracers' uptake by fluorescence microscopy: direct and droplet approach

    NASA Astrophysics Data System (ADS)

    Gallina, M. E.; Kim, T. J.; Vasquez, J.; Tuerkcan, S.; Abbyad, P.; Pratx, G.

    2017-02-01

    Radionuclides are used for sensitive and specific detection of small molecules in vivo and in vitro. Recently, radioluminescence microscopy extended their use to single-cell studies. Here we propose a new single-cell radioisotopic assay that improves throughput while adding sorting capabilities. The new method uses fluorescence-based sensor for revealing single-cell interactions with radioactive molecular markers. This study focuses on comparing two different experimental approaches. Several probes were tested and Dihydrorhodamine 123 was selected as the best compromise between sensitivity, brightness and stability. The sensor was incorporated either directly within the cell cytoplasm (direct approach), or it was coencapsulated with radiolabeled single-cells in oil-dispersed water droplets (droplet approach). Both approaches successfully activated the fluorescence signal following cellular uptake of 18F-fluorodeoxyglucose (FDG) and external Xrays exposure. The direct approach offered single-cell resolution and longtime stability ( > 20 hours), moreover it could discriminate FDG uptake at labelling concentration as low as 300 μCi/ml. In cells incubated with Dihydrorhodamine 123 after exposure to high radiation doses (8-16 Gy), the fluorescence signal was found to increase with the depletion of ROS quenchers. On the other side, the droplet approach required higher labelling concentrations (1.00 mCi/ml), and, at the current state of art, three cells per droplet are necessary to produce a fluorescent signal. This approach, however, is independent on cellular oxidative stress and, with further improvements, will be more suitable for studying heterogeneous populations. We anticipate this technology to pave the way for the analysis of single-cell interactions with radiomarkers by radiofluorogenic-activated single-cell sorting.

  15. Evaluation of the influence of the conjugation site of the chelator agent HYNIC to GLP1 antagonist radiotracer for insulinoma diagnosis.

    PubMed

    Faintuch, Bluma Linkowski; Seo, Daniele; Oliveira, Érica Aparecida De; Targino, Roselaine Campos; Moro, Ana Maria

    2017-01-26

    Radiotracer diagnosis of insulinoma, can be done using somatostatin or glucagon-like peptide 1 (GLP-1). Performance of GLP-1 antagonists tends to be better than of agonists. We investigated the uptake of the antagonist exendin (9-39), radiolabeled with technetium-99m. Two different sites of the biomolecule were selected for chelator attachment. HYNIC-βAla chelator attached to serine (C- terminus) of exendin, was associated with higher tumor uptake than to aspartate (N- terminus). In conclusion the chelator position in the biomolecule influenced receptor uptake.

  16. Operationally Efficient Propulsion System Study (OEPSS) data book. Volume 5: OEPSS final briefing for first year study

    NASA Technical Reports Server (NTRS)

    Wong, George S.; Waldrop, Glen S.

    1990-01-01

    This study was initiated to identify operations problems and cost drivers for current propulsion systems and to identify technology and design approaches to increase the operational efficiency and reduce operations costs for future propulsion systems. To provide readily usable data for the Advanced Launch System (ALS) Program, the results of the Operationally Efficient Propulsion System Study (OEPSS) were organized into a series of OEPSS Data Books. This volume contains the final briefing on the OEPSS first-year effort. This briefing was presented to MSFC as part of an effort to promote greater interaction between the design community and the launch site operator.

  17. (Development of gamma emitting, receptor-binding, radiotracers for imaging the brain and pancreas)

    SciTech Connect

    Not Available

    1989-01-01

    This progress report covers the period from March 1, 1987 to Feb. 28, 1988. In studies to better understand the nature of the m-AChR receptor subtypes, we have generated a manuscript which has been submitted for publication in Life sciences entitled: The effect of chronic atropine and diisopropylfluorophosphate on rat brain muscarinic acetylcholine receptor subtype concentrations. We have also developed a more direct synthesis of 3-quinuclidinyl 4-iodobenzilate and its analogues. During this contract period, we have been involved with the synthesis of analogues 3-quinuclidinyl benzilate (QNB). We have determined the affinity constants of various compounds synthesized this year for the muscarinic receptor from rat corpus striatum. We have continued our investigation of the m-AChR in pancreas. 25 refs., 3 figs., 5 tabs.

  18. Marine anthropogenic radiotracers in the Southern Hemisphere: New sampling and analytical strategies

    NASA Astrophysics Data System (ADS)

    Levy, I.; Povinec, P. P.; Aoyama, M.; Hirose, K.; Sanchez-Cabeza, J. A.; Comanducci, J.-F.; Gastaud, J.; Eriksson, M.; Hamajima, Y.; Kim, C. S.; Komura, K.; Osvath, I.; Roos, P.; Yim, S. A.

    2011-04-01

    The Japan Agency for Marine Earth Science and Technology conducted in 2003-2004 the Blue Earth Global Expedition (BEAGLE2003) around the Southern Hemisphere Oceans, which was a rare opportunity to collect many seawater samples for anthropogenic radionuclide studies. We describe here sampling and analytical methodologies based on radiochemical separations of Cs and Pu from seawater, as well as radiometric and mass spectrometry measurements. Several laboratories took part in radionuclide analyses using different techniques. The intercomparison exercises and analyses of certified reference materials showed a reasonable agreement between the participating laboratories. The obtained data on the distribution of 137Cs and plutonium isotopes in seawater represent the most comprehensive results available for the Southern Hemisphere Oceans.

  19. Single-photon emitting radiotracers produced by cyclotrons for myocardial imaging

    NASA Astrophysics Data System (ADS)

    Kulkarni, Padmakar V.

    1989-04-01

    Radionuclides produced by cyclotron have played an important role in clinical nuclear medicine. Among these, 210T1, 123I, 111In and 67Ga in various chemical forms have important applications in the diagnosis of cancer and heart disease using scintigraphic imaging techniques. Cardiac imaging using nuclear scintigraphy and echocardiography has been among the fastest growing diagnostic technologies in medicine during the past 15 years. Development of new tracers in conjunction with new equipment with better resolution has contributed to the better quantification and analysis of test results. The development of new biomolecules, monoclonal antibodies to myosin, platelets, fibrin and other receptor binding agents has added a new dimension to nuclear imaging studies.

  20. Samarium oxide as a radiotracer to evaluate the in vivo biodistribution of PLGA nanoparticles

    NASA Astrophysics Data System (ADS)

    Mandiwana, Vusani; Kalombo, Lonji; Venter, Kobus; Sathekge, Mike; Grobler, Anne; Zeevaart, Jan Rijn

    2015-09-01

    Developing nanoparticulate delivery systems that will allow easy movement and localization of a drug to the target tissue and provide more controlled release of the drug in vivo is a challenge in nanomedicine. The aim of this study was to evaluate the biodistribution of poly( d, l-lactide- co-glycolide) (PLGA) nanoparticles containing samarium-153 oxide ([153Sm]Sm2O3) in vivo to prove that orally administered nanoparticles alter the biodistribution of a drug. These were then activated in a nuclear reactor to produce radioactive 153Sm-loaded-PLGA nanoparticles. The nanoparticles were characterized for size, zeta potential, and morphology. The nanoparticles were orally and intravenously (IV) administered to rats in order to trace their uptake through imaging and biodistribution studies. The 153Sm-loaded-PLGA nanoparticles had an average size of 281 ± 6.3 nm and a PDI average of 0.22. The zeta potential ranged between 5 and 20 mV. The [153Sm]Sm2O3 loaded PLGA nanoparticles, orally administered were distributed to most organs at low levels, indicating that there was absorption of nanoparticles. While the IV injected [153Sm]Sm2O3-loaded PLGA nanoparticles exhibited the highest localization of nanoparticles in the spleen (8.63 %ID/g) and liver (3.07 %ID/g), confirming that nanoparticles are rapidly removed from the blood by the RES, leading to rapid uptake in the liver and spleen. From the biodistribution data obtained, it is clear that polymeric nanoscale delivery systems would be suitable for improving permeability and thus the bioavailability of therapeutic compounds.

  1. Photochemical Ignition Studies. 3. Ignition by Efficient and Resonant Multiphoton Photochemical Formation of Microplasmas

    DTIC Science & Technology

    1987-06-01

    Security Ct14sfIcation) PHOTOCHEMICAL IGNITION STUDIES. I11. IGNITION BY EFFICIENT AND RESONANT MULTIPHOTON PHOTOCHEMICAL FORMATION OF MICROPLASMAS 12... Microplasmas 07 04ý 19. ABSTRACT (Coninu On 06 it= iP rwouiry and ikti n~jnilW) ;;is is the third of a series of reports concerning the activation...p--spectral studies were carried out on 02 and N 0 flows alone. These indicated a resonant formation of a microplasma with a fifetime on the order

  2. Comparison of three high affinity SPECT radiotracers for the dopamine D2 receptor.

    PubMed

    al-Tikriti, M S; Baldwin, R M; Zea-Ponce, Y; Sybirska, E; Zoghbi, S S; Laruelle, M; Malison, R T; Kung, H F; Kessler, R M; Charney, D S

    1994-02-01

    The regional brain distribution and pharmacological specificity of three high affinity tracers for the dopamine (DA) D2 receptor: [123I]IBF, [123I]epidepride, and [123I]2'-ISP were assessed by SPECT imaging of non-human primates. The ratios of striatal-to-occipital activities at the time of peak striatal uptake were 2.2, 6.3 and 1.7, respectively. From the peak striatal activities, washout rates were 33, 4 and 16%/h for [123I]IBF, [123I]epidepride and [123I]2'-ISP, respectively. The reversibility of the striatal uptake of all three agents was demonstrated by the rapid displacement induced by the dopamine D2 selective antipsychotic agent raclopride, which increased washout rates to 96, 58 and 43%/h. The administration of d-amphetamine, which induces release of dopamine, had no noticeable effect on [123I]epidepride but increased the washout rate of [123I]IBF. These results suggest that, among these three agents, [123I]epidepride is the superior tracer for in vivo displacement studies because of its slow washout and high target-to-background ratios. However, for tracer kinetic modeling, [123I]IBF may be the superior agent because of its early time of peak uptake and its higher target-to-background ratios than [123I]2'-ISP.

  3. Positron emission tomography (PET) imaging with 18F-based radiotracers

    PubMed Central

    Alauddin, Mian M

    2012-01-01

    Positron Emission Tomography (PET) is a nuclear medicine imaging technique that is widely used in early detection and treatment follow up of many diseases, including cancer. This modality requires positron-emitting isotope labeled biomolecules, which are synthesized prior to perform imaging studies. Fluorine-18 is one of the several isotopes of fluorine that is routinely used in radiolabeling of biomolecules for PET; because of its positron emitting property and favorable half-life of 109.8 min. The biologically active molecule most commonly used for PET is 2-deoxy-2-18F-fluoro-β-D-glucose (18F-FDG), an analogue of glucose, for early detection of tumors. The concentrations of tracer accumulation (PET image) demonstrate the metabolic activity of tissues in terms of regional glucose metabolism and accumulation. Other tracers are also used in PET to image the tissue concentration. In this review, information on fluorination and radiofluorination reactions, radiofluorinating agents, and radiolabeling of various compounds and their application in PET imaging is presented. PMID:23133802

  4. Tissue biodistribution and blood clearance rates of intravenously administered carbon nanotube radiotracers

    NASA Astrophysics Data System (ADS)

    Singh, Ravi; Pantarotto, Davide; Lacerda, Lara; Pastorin, Giorgia; Klumpp, Cédric; Prato, Maurizio; Bianco, Alberto; Kostarelos, Kostas

    2006-02-01

    Carbon nanotubes (CNT) are intensively being developed for biomedical applications including drug and gene delivery. Although all possible clinical applications will require compatibility of CNT with the biological milieu, their in vivo capabilities and limitations have not yet been explored. In this work, water-soluble, single-walled CNT (SWNT) have been functionalized with the chelating molecule diethylentriaminepentaacetic (DTPA) and labeled with indium (111In) for imaging purposes. Intravenous (i.v.) administration of these functionalized SWNT (f-SWNT) followed by radioactivity tracing using gamma scintigraphy indicated that f-SWNT are not retained in any of the reticuloendothelial system organs (liver or spleen) and are rapidly cleared from systemic blood circulation through the renal excretion route. The observed rapid blood clearance and half-life (3 h) of f-SWNT has major implications for all potential clinical uses of CNT. Moreover, urine excretion studies using both f-SWNT and functionalized multiwalled CNT followed by electron microscopy analysis of urine samples revealed that both types of nanotubes were excreted as intact nanotubes. This work describes the pharmacokinetic parameters of i.v. administered functionalized CNT relevant for various therapeutic and diagnostic applications. nanomedicine | blood circulation half-life | drug delivery | pharmacokinetics | nanotoxicology

  5. Home energy efficiency and radon related risk of lung cancer: modelling study

    PubMed Central

    Milner, James; Shrubsole, Clive; Das, Payel; Jones, Benjamin; Ridley, Ian; Chalabi, Zaid; Hamilton, Ian; Armstrong, Ben; Davies, Michael

    2014-01-01

    Objective To investigate the effect of reducing home ventilation as part of household energy efficiency measures on deaths from radon related lung cancer. Design Modelling study. Setting England. Intervention Home energy efficiency interventions, motivated in part by targets for reducing greenhouse gases, which entail reduction in uncontrolled ventilation in keeping with good practice guidance. Main outcome measures Modelled current and future distributions of indoor radon levels for the English housing stock and associated changes in life years due to lung cancer mortality, estimated using life tables. Results Increasing the air tightness of dwellings (without compensatory purpose-provided ventilation) increased mean indoor radon concentrations by an estimated 56.6%, from 21.2 becquerels per cubic metre (Bq/m3) to 33.2 Bq/m3. After the lag in lung cancer onset, this would result in an additional annual burden of 4700 life years lost and (at peak) 278 deaths. The increases in radon levels for the millions of homes that would contribute most of the additional burden are below the threshold at which radon remediation measures are cost effective. Fitting extraction fans and trickle ventilators to restore ventilation will help offset the additional burden but only if the ventilation related energy efficiency gains are lost. Mechanical ventilation systems with heat recovery may lower radon levels and the risk of cancer while maintaining the advantage of energy efficiency for the most airtight dwellings but there is potential for a major adverse impact on health if such systems fail. Conclusion Unless specific remediation is used, reducing the ventilation of dwellings will improve energy efficiency only at the expense of population wide adverse impact on indoor exposure to radon and risk of lung cancer. The implications of this and other consequences of changes to ventilation need to be carefully evaluated to ensure that the desirable health and environmental benefits of

  6. Home energy efficiency and radon related risk of lung cancer: modelling study.

    PubMed

    Milner, James; Shrubsole, Clive; Das, Payel; Jones, Benjamin; Ridley, Ian; Chalabi, Zaid; Hamilton, Ian; Armstrong, Ben; Davies, Michael; Wilkinson, Paul

    2014-01-10

    To investigate the effect of reducing home ventilation as part of household energy efficiency measures on deaths from radon related lung cancer. Modelling study. England. Home energy efficiency interventions, motivated in part by targets for reducing greenhouse gases, which entail reduction in uncontrolled ventilation in keeping with good practice guidance. Modelled current and future distributions of indoor radon levels for the English housing stock and associated changes in life years due to lung cancer mortality, estimated using life tables. Increasing the air tightness of dwellings (without compensatory purpose-provided ventilation) increased mean indoor radon concentrations by an estimated 56.6%, from 21.2 becquerels per cubic metre (Bq/m(3)) to 33.2 Bq/m(3). After the lag in lung cancer onset, this would result in an additional annual burden of 4700 life years lost and (at peak) 278 deaths. The increases in radon levels for the millions of homes that would contribute most of the additional burden are below the threshold at which radon remediation measures are cost effective. Fitting extraction fans and trickle ventilators to restore ventilation will help offset the additional burden but only if the ventilation related energy efficiency gains are lost. Mechanical ventilation systems with heat recovery may lower radon levels and the risk of cancer while maintaining the advantage of energy efficiency for the most airtight dwellings but there is potential for a major adverse impact on health if such systems fail. Unless specific remediation is used, reducing the ventilation of dwellings will improve energy efficiency only at the expense of population wide adverse impact on indoor exposure to radon and risk of lung cancer. The implications of this and other consequences of changes to ventilation need to be carefully evaluated to ensure that the desirable health and environmental benefits of home energy efficiency are not compromised by avoidable negative impacts

  7. Analytical and experimental study of structurally efficient composite hat-stiffened panels loaded in axial compression

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Mikulus, M. M., Jr.

    1976-01-01

    Structural efficiency studies were made to determine the weight saving potential of graphite/epoxy composite structures for compression panel applications. Minimum weight hat-stiffened and open corrugation configurations were synthesized using a nonlinear mathematical programming technique. Selected configurations were built and tested to study local and Euler buckling characteristics. Test results for 23 panels critical in local buckling and six panels critical in Euler buckling are compared with analytical results obtained using the BUCLASP-2 branched plate buckling program. A weight efficiency comparison is made between composite and aluminum compression panels using metal test data generated by the NACA. Theoretical studies indicate that potential weight savings of up to 50% are possible for composite hat-stiffened panels when compared with similar aluminum designs. Weight savings of 32% to 42% were experimentally achieved. Experience suggests that most of the theoretical weight saving potential is available if design deficiencies are eliminated and strict fabrication control is exercised.

  8. The studies of phase equilibria and efficiency assessment for self-emulsifying lipid-based formulations.

    PubMed

    Shahba, Ahmad Abdul-Wahhab; Mohsin, Kazi; Alanazi, Fars Kaed

    2012-06-01

    The study was designed to build up a database for the evaluation of the self-emulsifying lipid formulations performance. A standard assessment method was constructed to evaluate the self-emulsifying efficiency of the formulations based on five parameters including excipients miscibility, spontaneity, dispersibility, homogeneity, and physical appearance. Equilibrium phase studies were conducted to investigate the phase changes of the anhydrous formulation in response to aqueous dilution. Droplet size studies were carried out to assess the influence of lipid and surfactant portions on the resulted droplet size upon aqueous dilution. Formulations containing mixed glycerides showed enhanced self-emulsification with both lipophilic and hydrophilic surfactants. Increasing the polarity of the lipid portion in the formulation leaded to progressive water solubilization capacity. In addition, formulations containing medium chain mixed glycerides and hydrophilic surfactants showed lower droplet size compared with their long chain and lipophilic counterparts. The inclusion of mixed glycerides in the lipid formulations enormously enhances the formulation efficiency.

  9. Electromagnetic Investigations and Power Converter Efficiency Studies on a Laboratory Made Induction Heating Prototype

    NASA Astrophysics Data System (ADS)

    Roy, M.; Sengupta, M.

    2013-09-01

    In this paper electromagnetic analysis and power converter efficiency has been studied on a laboratory prototype induction heating coil. An electromagnetic field based study was first done for the induction heating coil used in the experimental set-up using available Finite Element Analysis package software (FEMM 4.2). The results of the FEM based study are also used in the choice of the operating frequency depending on the applications. Thereafter verifications are done experimentally on a small-scale laboratory developed setup. The approach to be adopted for choice of induction heating operating frequency and the choice of converter type, based on the efficiency and performance, are also briefly presented here. Oscilloscope traces uphold the accuracy of the practical tests conducted.

  10. Assessing soil redistribution on slope transects at different temporal scales by using radiotracers.

    NASA Astrophysics Data System (ADS)

    Gaspar, L.; Navas, A.; Machín, J.

    2009-04-01

    Soil erosion and sediment deposition represent a serious problem throughout the world, because of their impact on sustainable agricultural production as well as on environmental conservation. The isotopic techniques based on the use of fallout radionuclides 137Cs, 210Pbexand 7Be as tracers allow to obtain estimates of soil redistribution rates within undisturbed and cultivated landscapes over a range of different timescales. Increasing risk of erosion under climate change regimes precise data on soil erosion rates at different temporal scales. The 137Cs technique (T1•2=30.17 years), an artificial radionuclide coming from nuclear test, is the most widely used of the fallout radionuclides, and provides results of medium-term average rates of soil redistribution. 210Pbex (T1•2= 22.26 years), a natural geogenic radionuclide, offers estimates to quantify large-term soil erosion rates, and reflect a longer period of time, between 100 and 150 years than the 40 years with 137Cs . The study area is located in the subhumid mountain in the north of Spain. To document soil redistribution, 24 soil cores spaced 50 m apart were collected along slope transect. The site selected to establish the local reference inventory was situated in the upper part of the transect, on a flat area under natural forest. The reference inventory for 137Cs is 1570 Bq m-2 and for 210Pbex is 1891Bq m-2. Comparison of 137Cs versus 210Pb profiles for the uncultivated soils show that the maximum concentrations of both radionuclides occur at the surface horizon. For the cultivated soils the two radionuclides are relatively uniformly distributed with depth. However 210Pbex concentrations show some evidence of increasing slightly towards the surface. The areal activity density (inventory) showed large variations, between 489.2 - 6080.1 Bq m-2 for 137Cs, and 117.6 - 7788.3 Bq m-2 for 210Pbex. The 137Cs and 210Pbex inventories at the middle of the slope were extremely low in cultivated soils, and the highest

  11. Pollutant emissions and energy efficiency of Chinese gasifier cooking stoves and implications for future intervention studies.

    PubMed

    Carter, Ellison M; Shan, Ming; Yang, Xudong; Li, Jiarong; Baumgartner, Jill

    2014-06-03

    Household air pollution from solid fuel combustion is the leading environmental health risk factor globally. In China, almost half of all homes use solid fuel to meet their household energy demands. Gasifier cookstoves offer a potentially affordable, efficient, and low-polluting alternative to current solid fuel combustion technology, but pollutant emissions and energy efficiency performance of this class of stoves are poorly characterized. In this study, four Chinese gasifier cookstoves were evaluated for their pollutant emissions and efficiency using the internationally recognized water boiling test (WBT), version 4.1.2. WBT performance indicators included PM2.5, CO, and CO2 emissions and overall thermal efficiency. Laboratory investigation also included evaluation of pollutant emissions (PM2.5 and CO) under stove operating conditions designed to simulate common Chinese cooking practices. High power average overall thermal efficiencies ranged from 22 to 33%. High power average PM2.5 emissions ranged from 120 to 430 mg/MJ of useful energy, and CO emissions ranged from 1 to 30 g/MJ of useful energy. Compared with several widely disseminated "improved" cookstoves selected from the literature, on average, the four Chinese gasifier cookstoves had lower PM2.5 emissions and higher CO emissions. The recent International Organization for Standardization (ISO) International Workshop Agreement on tiered cookstove ranking was developed to help classify stove performance and identify the best-performing stoves. The results from this study highlight potential ways to further improve this approach. Medium power stove operation emitted nearly twice as much PM2.5 as was emitted during high power stove operation, and the lighting phase of a cooking event contributed 45% and 34% of total PM2.5 emissions (combined lighting and cooking). Future approaches to laboratory-based testing of advanced cookstoves could improve to include greater differentiation between different modes of

  12. ACEEE 1990 summer study on energy efficiency in buildings: Proceedings. Volume 4, Environment

    SciTech Connect

    Not Available

    1990-12-31

    This panel of the 1990 Summer Study examines the potential contribution of energy efficiency in buildings to environmental protection. The Panel also covers other aspects of the relationship between building efficiency and the environment, including indoor air quality, radon exposure, and urban heat island effects. Global environmental risks, growing interest in market-based environmental regulation, and the integration of environmental and energy planning have focused attention on energy efficiency as a low-cost pollution prevention strategy. This combination of factors is making public concern over the environment a driving force for improvements in energy efficiency. The environmental issues that are related to air pollution include the group of problems that have been in the public consciousness for two decades: acid rain, urban smog, ozone depletion, and general outdoor air pollution. Indoor air quality is also an air pollution problem. Whereas indoor air pollution causes direct health impacts on occupants of the space in question, outdoor air pollution affects others, often at remote locations, in ways that are more difficult to quantify. There is an immediacy to the indoor pollution issue that has important policy implications. The papers in the indoor air quality and radon sessions focus on several of the important issues in this area. For these conference proceedings, individual papers are processed separately for the Energy Data Base.

  13. Efficiency of particle acceleration at interplanetary shocks: Statistical study of STEREO observations

    NASA Astrophysics Data System (ADS)

    Dresing, N.; Theesen, S.; Klassen, A.; Heber, B.

    2016-04-01

    Context. Among others, shocks are known to be accelerators of energetic charged particles. However, many questions regarding the acceleration efficiency and the required conditions are not fully understood. In particular, the acceleration of electrons by shocks is often questioned. Aims: In this study we determine the efficiency of interplanetary shocks for <100 keV electrons, and for ions at ~0.1 and ~2 MeV energies, as measured by the Solar Electron and Proton Telescope (SEPT) instruments aboard the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft. Methods: We employ an online STEREO in situ shock catalog that lists all shocks observed between 2007 and mid 2014 (observed by STEREO A) and until end of 2013 (observed by STEREO B). In total 475 shocks are listed. To determine the particle acceleration efficiency of these shocks, we analyze the associated intensity increases (shock spikes) during the shock crossings. For the near-relativistic electrons, we take into account the issue of possible ion contamination in the SEPT instrument. Results: The highest acceleration efficiency is found for low energy ions (0.1 MeV), which show a shock-associated increase at 27% of all shocks. The 2 MeV ions show an associated increase only during 5% of the shock crossings. In the case of the electrons, the shocks are nearly ineffective. Only five shock-associated electron increases were found, which correspond to only 1% of all shock crossings.

  14. Radiotracer applications in Australia

    SciTech Connect

    Airey, P.L.; Charlton, J.S.

    1994-12-31

    Radioisotope tracers have been applied in Australia since the early 1950`s to a wide range of industrial and environmental problems. A number of key projects are described. A development of a commercial service through the Tracerco Australasia joint venture is outlined. The challenges and opportunities facing tracer technology in the modem industrial era are examined.

  15. Costs and Efficiency of Online and Offline Recruitment Methods: A Web-Based Cohort Study

    PubMed Central

    Riis, Anders H; Hatch, Elizabeth E; Wise, Lauren A; Nielsen, Marie G; Rothman, Kenneth J; Toft Sørensen, Henrik; Mikkelsen, Ellen M

    2017-01-01

    Background The Internet is widely used to conduct research studies on health issues. Many different methods are used to recruit participants for such studies, but little is known about how various recruitment methods compare in terms of efficiency and costs. Objective The aim of our study was to compare online and offline recruitment methods for Internet-based studies in terms of efficiency (number of recruited participants) and costs per participant. Methods We employed several online and offline recruitment methods to enroll 18- to 45-year-old women in an Internet-based Danish prospective cohort study on fertility. Offline methods included press releases, posters, and flyers. Online methods comprised advertisements placed on five different websites, including Facebook and Netdoktor.dk. We defined seven categories of mutually exclusive recruitment methods and used electronic tracking via unique Uniform Resource Locator (URL) and self-reported data to identify the recruitment method for each participant. For each method, we calculated the average cost per participant and efficiency, that is, the total number of recruited participants. Results We recruited 8252 study participants. Of these, 534 were excluded as they could not be assigned to a specific recruitment method. The final study population included 7724 participants, of whom 803 (10.4%) were recruited by offline methods, 3985 (51.6%) by online methods, 2382 (30.8%) by online methods not initiated by us, and 554 (7.2%) by other methods. Overall, the average cost per participant was €6.22 for online methods initiated by us versus €9.06 for offline methods. Costs per participant ranged from €2.74 to €105.53 for online methods and from €0 to €67.50 for offline methods. Lowest average costs per participant were for those recruited from Netdoktor.dk (€2.99) and from Facebook (€3.44). Conclusions In our Internet-based cohort study, online recruitment methods were superior to offline methods in terms

  16. Costs and Efficiency of Online and Offline Recruitment Methods: A Web-Based Cohort Study.

    PubMed

    Christensen, Tina; Riis, Anders H; Hatch, Elizabeth E; Wise, Lauren A; Nielsen, Marie G; Rothman, Kenneth J; Toft Sørensen, Henrik; Mikkelsen, Ellen M

    2017-03-01

    The Internet is widely used to conduct research studies on health issues. Many different methods are used to recruit participants for such studies, but little is known about how various recruitment methods compare in terms of efficiency and costs. The aim of our study was to compare online and offline recruitment methods for Internet-based studies in terms of efficiency (number of recruited participants) and costs per participant. We employed several online and offline recruitment methods to enroll 18- to 45-year-old women in an Internet-based Danish prospective cohort study on fertility. Offline methods included press releases, posters, and flyers. Online methods comprised advertisements placed on five different websites, including Facebook and Netdoktor.dk. We defined seven categories of mutually exclusive recruitment methods and used electronic tracking via unique Uniform Resource Locator (URL) and self-reported data to identify the recruitment method for each participant. For each method, we calculated the average cost per participant and efficiency, that is, the total number of recruited participants. We recruited 8252 study participants. Of these, 534 were excluded as they could not be assigned to a specific recruitment method. The final study population included 7724 participants, of whom 803 (10.4%) were recruited by offline methods, 3985 (51.6%) by online methods, 2382 (30.8%) by online methods not initiated by us, and 554 (7.2%) by other methods. Overall, the average cost per participant was €6.22 for online methods initiated by us versus €9.06 for offline methods. Costs per participant ranged from €2.74 to €105.53 for online methods and from €0 to €67.50 for offline methods. Lowest average costs per participant were for those recruited from Netdoktor.dk (€2.99) and from Facebook (€3.44). In our Internet-based cohort study, online recruitment methods were superior to offline methods in terms of efficiency (total number of participants

  17. A rapid and efficient preparation of [123I]radiopharmaceuticals using a small HPLC (Rocket) column.

    PubMed

    Katsifis, Andrew; Papazian, Vahan; Jackson, Timothy; Loc'h, Christian

    2006-01-01

    A simplified method for the rapid and efficient preparation of [(123)I]radiopharmaceuticals is described. Three radiopharmaceuticals, [(123)I]beta-CIT, [(123)I]MIBG and [(123)I]clioquinol, were synthesised and purified as model compounds. The radiotracers were labelled with iodine-123 using electrophilic oxidative conditions and purified by a compact semi-preparative reverse phase column (C-18, 3 microm, 7 x 53 mm, Alltima Rocket, Alltech) using aqueous-ethanol as HPLC solvents that were directly used for radiopharmaceutical formulation. The radiochemical purity of the radioiodinated tracers as assessed by analytical HPLC was higher than 99% with specific activity higher than 3 GBq/nmol. The total preparation time of a radiotracer ranged from 40 to 60 min and, starting from 3.7 GBq of iodine-123, more than 2.5 GBq of formulated radiopharmaceuticals were available for clinical investigations.

  18. Study on storage efficiency of the fresh food e-commerce

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Sun, Jie; Li, Huihui

    2017-06-01

    As the last cake in the area of e-commerce industry, the temperature of fresh food e-commerce is always rising starting from about 2014. This paper is based on the imperfection that the existing study about fresh food e-commerce is lack of studies on storage efficiency. And we took some variables in this paper such as consumers’ satisfaction and length for preservation and storage time. On this basis we built the model of storage efficiency of fresh food e-commerce. We find that as the development of fresh food e-commerce, the fresh food e-commerce enterprise will pay more attention to the consumers’ satisfaction. They can take some effective ways like reducing the wastage of fresh food and lengthening the refreshing time of fresh food and so on.

  19. Ion generation and CPC detection efficiency studies in sub 3-nm size range

    SciTech Connect

    Kangasluoma, J.; Junninen, H.; Sipilae, M.; Kulmala, M.; Petaejae, T.; Lehtipalo, K.; Mikkilae, J.; Vanhanen, J.; Attoui, M.; Worsnop, D.

    2013-05-24

    We studied the chemical composition of commonly used condensation particle counter calibration ions with a mass spectrometer and found that in our calibration setup the negatively charged ammonium sulphate, sodium chloride and tungsten oxide are the least contaminated whereas silver on both positive and negative and the three mentioned earlier in positive mode are contaminated with organics. We report cut-off diameters for Airmodus Particle Size Magnifier (PSM) 1.1, 1.3, 1.4, 1.6 and 1.6-1.8 nm for negative sodium chloride, ammonium sulphate, tungsten oxide, silver and positive organics, respectively. To study the effect of sample relative humidity on detection efficiency of the PSM we used different humidities in the differential mobility analyzer sheath flow and found that with increasing relative humidity also the detection efficiency of the PSM increases.

  20. Efficiency and substitution in pollution abatement: Three case studies. World Bank discussion papers

    SciTech Connect

    Anderson, D.; Cavendish, W.

    1992-01-01

    The studies presented in the report serve to show by reference to particular cases why good economic policies are often beneficial for the environment--and conversely why good environmental policies are good for economic growth and development. Two findings of particular interest were: the huge scale of the prospective economic benefits from reforming prices and institutional arrangements in the sectors studied (electricity, transport and water supply), and the scope for pollution abatement through the adoption of low-polluting technologies and practices. Although the costs of the latter are sometimes significant, they are generally small when compared with the benefits of improving economic efficiency. The combination of efficiency and substitution is a powerful one from economic as well as environmental perspectives.

  1. A study of the factors which control the efficiency of ion-implanted silicon solar cells

    NASA Technical Reports Server (NTRS)

    Douglas, E. C.; Daiello, R. V.

    1980-01-01

    The objective of this work was to determine experimentally the ion-implantation parameters and furnace annealing conditions required to produce high-efficiency solar cells. A comprehensive experimental study was conducted in which the optimum ion-implantation parameters were found by a systematic variation of the implant parameters followed by detailed studies of solar-cell devices. Two furnace heat-treatment techniques were found which effectively anneal the implanted layers and at the same time preserve or improve the diffusion length in the bulk silicon. Detailed characteristics of both the junction and bulk properties of solar cells fabricated over the spectrum of implant parameters are discussed. Optimized implant parameters and annealing conditions were found which allow for the fabrication of 14-15-percent (AM1) efficient solar cells.

  2. Operationally Efficient Propulsion System Study (OEPSS) data book. Volume 3: Operations technology

    NASA Technical Reports Server (NTRS)

    Vilja, John O.

    1990-01-01

    The study was initiated to identify operational problems and cost drivers for current propulsion systems and to identify technology and design approaches to increase the operational efficiency and reduce operations costs for future propulsion systems. To provide readily usable data for the Advanced Launch System (ALS) program, the results of the OEPSS study were organized into a series of OEPSS Data Books. This volume describes operations technologies that will enhance operational efficiency of propulsion systems. A total of 15 operations technologies were identified that will eliminate or mitigate operations problems described in Volume 2. A recommended development plan is presented for eight promising technologies that will simplify the propulsion system and reduce operational requirements.

  3. A Study on Market Efficiency of Selected Commodity Derivatives Traded on NCDEX During 2011

    NASA Astrophysics Data System (ADS)

    Sajipriya, N.

    2012-10-01

    The study aims at testing the weak form of Efficient Market Hypothesis in the context of an emerging commodity market - National Commodity Derivatives Exchange (NCDEX), which is considered as the prime commodity derivatives market in India. The study considered daily spot and futures prices of five selected commodities traded on NCDEX over 12 month period (the futures contracts originating and expiring during the period January 2011 to December 2011) The five commodities chosen are Pepper, Crude palm Oil, steel silver and Chana as they account for almost two-thirds of the value of agricultural commodity derivatives traded on NCDEX. The results of Run test indicate that both spot and futures prices are weak form efficient

  4. Experimental study of the short diffuser design influence on the efficiency of air cooled condenser

    NASA Astrophysics Data System (ADS)

    Fil'kin, N. Yu.; Yusha, V. L.

    2017-08-01

    The article is devoted to increase in efficiency of refrigerators air condensers by improvement of a flowing part in the so-called short diffusers incorporated in their design. The installation of the flowing part guiding short diffusers which improves the distribution of the cooling air stream on the condenser heat exchange surface is offered. This decision allows to increase the condenser power that is confirmed by the results of the experimental studies presented in the article.

  5. The effect of a cadence retraining protocol on running biomechanics and efficiency: a pilot study.

    PubMed

    Hafer, Jocelyn F; Brown, Allison M; deMille, Polly; Hillstrom, Howard J; Garber, Carol Ewing

    2015-01-01

    Many studies have documented the association between mechanical deviations from normal and the presence or risk of injury. Some runners attempt to change mechanics by increasing running cadence. Previous work documented that increasing running cadence reduces deviations in mechanics tied to injury. The long-term effect of a cadence retraining intervention on running mechanics and energy expenditure is unknown. This study aimed to determine if increasing running cadence by 10% decreases running efficiency and changes kinematics and kinetics to make them less similar to those associated with injury. Additionally, this study aimed to determine if, after 6 weeks of cadence retraining, there would be carryover in kinematic and kinetic changes from an increased cadence state to a runner's preferred running cadence without decreased running efficiency. We measured oxygen uptake, kinematic and kinetic data on six uninjured participants before and after a 6-week intervention. Increasing cadence did not result in decreased running efficiency but did result in decreases in stride length, hip adduction angle and hip abductor moment. Carryover was observed in runners' post-intervention preferred running form as decreased hip adduction angle and vertical loading rate.

  6. Preliminary thermodynamic study for an efficient turbo-blower external combustion Rankine cycle

    NASA Astrophysics Data System (ADS)

    Romero Gómez, Manuel; Romero Gómez, Javier; Ferreiro Garcia, Ramón; Baaliña Insua, Álvaro

    2014-08-01

    This research paper presents a preliminary thermodynamic study of an innovative power plant operating under a Rankine cycle fed by an external combustion system with turbo-blower (TB). The power plant comprises an external combustion system for natural gas, where the combustion gases yield their thermal energy, through a heat exchanger, to a carbon dioxide Rankine cycle operating under supercritical conditions and with quasi-critical condensation. The TB exploits the energy from the pressurised exhaust gases for compressing the combustion air. The study is focused on the comparison of the combustion system's conventional technology with that of the proposed. An energy analysis is carried out and the effect of the flue gas pressure on the efficiency and on the heat transfer in the heat exchanger is studied. The coupling of the TB results in an increase in efficiency and of the convection coefficient of the flue gas with pressure, favouring a reduced volume of the heat exchanger. The proposed innovative system achieves increases in efficiency of around 12 % as well as a decrease in the heat exchanger volume of 3/5 compared with the conventional technology without TB.

  7. A study on the coagulation of polycyclic aromatic hydrocarbon clusters to determine their collision efficiency

    SciTech Connect

    Raj, Abhijeet; Sander, Markus; Janardhanan, Vinod; Kraft, Markus

    2010-03-15

    This paper presents a theoretical study on the physical interaction between polycyclic aromatic hydrocarbons (PAHs) and their clusters of different sizes in laminar premixed flames. Two models are employed for this study: a detailed PAH growth model, referred to as the kinetic Monte Carlo - aromatic site (KMC-ARS) model [Raj et al., Combust. Flame 156 (2009) 896-913]; and a multivariate PAH population balance model, referred to as the PAH - primary particle (PAH-PP) model. Both the models are solved by kinetic Monte Carlo methods. PAH mass spectra are generated using the PAH-PP model, and compared to the experimentally observed spectra for a laminar premixed ethylene flame. The position of the maxima of PAH dimers in the spectra and their concentrations are found to depend strongly on the collision efficiency of PAH coagulation. The variation in the collision efficiency with various flame and PAH parameters is studied to determine the factors on which it may depend. A correlation for the collision efficiency is proposed by comparing the computed and the observed spectra for an ethylene flame. With this correlation, a good agreement between the computed and the observed spectra for a number of laminar premixed ethylene flames is found. (author)

  8. A Successful Case Study of Small Business Energy Efficiency and Demand Response with Communicating Thermostats

    SciTech Connect

    Herter, Karen; Wayland, Seth; Rasin, Josh

    2009-08-12

    This report documents a field study of 78 small commercial customers in the Sacramento Municipal Utility District service territory who volunteered for an integrated energy-efficiency/demand-response (EE-DR) program in the summer of 2008. The original objective for the pilot was to provide a better understanding of demand response issues in the small commercial sector. Early findings justified a focus on offering small businesses (1) help with the energy efficiency of their buildings in exchange for occasional load shed, and (2) a portfolio of options to meet the needs of a diverse customer sector. To meet these expressed needs, the research pilot provided on-site energy efficiency advice and offered participants several program options, including the choice of either a dynamic rate or monthly payment for air-conditioning setpoint control. Overall results show that pilot participants had energy savings of 20%, and the potential for an additional 14% to 20% load drop during a 100 F demand response event. In addition to the efficiency-related bill savings, participants on the dynamic rate saved an estimated 5% on their energy costs compared to the standard rate. About 80% of participants said that the program met or surpassed their expectations, and three-quarters said they would probably or definitely participate again without the $120 participation incentive. These results provide evidence that energy efficiency programs, dynamic rates and load control programs can be used concurrently and effectively in the small business sector, and that communicating thermostats are a reliable tool for providing air-conditioning load shed and enhancing the ability of customers on dynamic rates to respond to intermittent price events.

  9. Energy efficiency in cognitive radio network: Study of cooperative sensing using different channel sensing methods

    NASA Astrophysics Data System (ADS)

    Cui, Chenxuan

    When cognitive radio (CR) operates, it starts by sensing spectrum and looking for idle bandwidth. There are several methods for CR to make a decision on either the channel is occupied or idle, for example, energy detection scheme, cyclostationary detection scheme and matching filtering detection scheme [1]. Among them, the most common method is energy detection scheme because of its algorithm and implementation simplicities [2]. There are two major methods for sensing, the first one is to sense single channel slot with varying bandwidth, whereas the second one is to sense multiple channels and each with same bandwidth. After sensing periods, samples are compared with a preset detection threshold and a decision is made on either the primary user (PU) is transmitting or not. Sometimes the sensing and decision results can be erroneous, for example, false alarm error and misdetection error may occur. In order to better control error probabilities and improve CR network performance (i.e. energy efficiency), we introduce cooperative sensing; in which several CR within a certain range detect and make decisions on channel availability together. The decisions are transmitted to and analyzed by a data fusion center (DFC) to make a final decision on channel availability. After the final decision is been made, DFC sends back the decision to the CRs in order to tell them to stay idle or start to transmit data to secondary receiver (SR) within a preset transmission time. After the transmission, a new cycle starts again with sensing. This thesis report is organized as followed: Chapter II review some of the papers on optimizing CR energy efficiency. In Chapter III, we study how to achieve maximal energy efficiency when CR senses single channel with changing bandwidth and with constrain on misdetection threshold in order to protect PU; furthermore, a case study is given and we calculate the energy efficiency. In Chapter IV, we study how to achieve maximal energy efficiency when CR

  10. Efficiency studies of hysteretic and PWM boost converters: Controller- and battery-type effects

    NASA Astrophysics Data System (ADS)

    Sanchez, Juan Herminio, III

    A continuous conduction boost converter is studied as a function of four battery types and two controllers. The battery types are alkaline, NiCd, NiMH, and sealed lead-acid. The controllers implement voltage-mode pulse-width modulation (PWM) and hysteretic current-mode (HCM) control schemes, respectively. The boost converter is designed to produce an output of 3W at 12V DC with battery voltages ranging from 6V to 3V. The study focuses on converter efficiency as affected by battery type, controller type, and the combined effects of battery type and controller type. Computer simulations predict and experimental results verify that differences in converter efficiency between the different battery types are due to differences in capacity, current-handling capabilities, and sustained voltage levels. The HCM controller uses a control scheme, in which the switching frequency decreases as battery voltage decreases, resulting in lower MOSFET switching losses. This effect partially compensates for the increased conduction losses in converter components as more current is drawn from batteries at lower input voltages. The PWM controller has a fixed switching frequency (50 kHz) and both its switching and conduction losses increase with decreasing input voltage. Efficiency levels of 88% are achieved for higher battery voltages, decreasing to 80% for lower voltages. A difference of up to 2% higher efficiency is observed in the HCM over the PWM. The major power losses are due to the combination of the inductor's ESR and the resistance of the wire used to increase the Hall-effect current sensor turns-ratio (increasing from 400mW to 1.2W). Simulations predict that in the absence of this resistance, efficiency levels of 95% can be achieved. Conduction losses through the rectifier are in the range of 40mW to 50mW for both controllers. MOSFET switching losses amount to 50mW for both controllers at high input voltages, increasing to 100mW for the PWM, but only to 65mW for the HCM at

  11. Tailored heterojunctions for efficient thin-film organic solar cells: a photoinduced absorption study

    NASA Astrophysics Data System (ADS)

    Schueppel, R.; Schmidt, K.; Uhrich, C.; Schulze, K.; Wynands, D.; Brédas, J. L.; Maennig, B.; Pfeiffer, M.; Leo, K.; Brier, E.; Reinold, E.; Bu, H.-B.; Baeuerle, P.

    2007-09-01

    Recently, we have demonstrated an open circuit voltage of 1.0V and a power conversion efficiency of 3.4% in thin film solar cells, utilizing a new acceptor-substituted oligothiophene with an optical gap of 1.77 eV as donor and C 60 as acceptor. Stimulated by this result, we systematically study the energy and electron transfer processes taking place at the oligothiophene:fullerene heterojunction along a homologous series of these oligothiophenes. The heterojunction is modified by tuning the HOMO level using different oligothiophene chain lengths, while the LUMO level is essentially fixed by the choice of the acceptor-type end-groups (dicyanovinyl) attached to the oligothiophene. We study electron transfer at the heterojunction to C 60 using photoinduced absorption. The observed transitions are unambiguously identified by TD-DFT calculations. With increasing the effective energy gap of the donor-acceptor pair, charge carrier dissociation following the photoinduced electron transfer is eventually replaced by recombination into the triplet state, which alters the photovoltaic operation conditions. Therefore, the optimum open-circuit voltage of a solar cell is a trade-off between an efficient charge separation at the interface and a maximized effective gap. We conclude that values between 1.0 and 1.1 V for the open-circuit voltage in our solar cell devices present an optimum, as higher voltages were only achieved with concomitant losses in charge separation efficiency.

  12. Low Noise Cruise Efficient Short Take-Off and Landing Transport Vehicle Study

    NASA Technical Reports Server (NTRS)

    Kim, Hyun D.; Berton, Jeffrey J.; Jones, Scott M.

    2007-01-01

    The saturation of the airspace around current airports combined with increasingly stringent community noise limits represents a serious impediment to growth in world aviation travel. Breakthrough concepts that both increase throughput and reduce noise impacts are required to enable growth in aviation markets. Concepts with a 25 year horizon must facilitate a 4x increase in air travel while simultaneously meeting community noise constraints. Attacking these horizon issues holistically is the concept study of a Cruise Efficient Short Take-Off and Landing (CESTOL) high subsonic transport under the NASA's Revolutionary Systems Concepts for Aeronautics (RSCA) project. The concept is a high-lift capable airframe with a partially embedded distributed propulsion system that takes a synergistic approach in propulsion-airframe-integration (PAI) by fully integrating the airframe and propulsion systems to achieve the benefits of both low-noise short take-off and landing (STOL) operations and efficient high speed cruise. This paper presents a summary of the recent study of a distributed propulsion/airframe configuration that provides low-noise STOL operation to enable 24-hour use of the untapped regional and city center airports to increase the capacity of the overall airspace while still maintaining efficient high subsonic cruise flight capability.

  13. Calorimetric study of the energy efficiency for ultrasound-induced radical formation.

    PubMed

    Kuijpers, M W A; Kemmere, M F; Keurentjes, J T F

    2002-05-01

    Energy conversion in sonochemistry is known to be an important factor for the development of industrial applications, however, the strong influence of the physical properties of the liquid on the ultrasound characteristics usually prevents an accurate determination of the chemical effects. In this study, the energy efficiency of the ultrasound-induced radical formation from methyl methacrylate has been investigated. The energy yield can be quantified by comparison of the ultrasonic power that is transferred to the liquid and the radical formation kinetics. Based on this method the influence of temperature and amplitude of the ultrasound horn on the energy efficiency has been determined. The energy yield for the formation of radicals from ultrasonic waves appears to be in the order of 5 x 10(-6) J/J. The energy conversion is the highest at low temperatures and at low amplitudes.

  14. A Study of Efficiency Droop Phenomenon in GaN-Based Laser Diodes before Lasing

    PubMed Central

    Feng, Mei-Xin; Sun, Qian; Liu, Jian-Ping; Li, Zeng-Cheng; Zhou, Yu; Gao, Hong-Wei; Zhang, Shu-Ming; Yang, Hui

    2017-01-01

    Carrier recombination behavior in c-plane GaN-based laser diodes (LDs) is numerically investigated by using the commercial software LASTIP. It is found that efficiency droop phenomenon does exist in GaN-based LDs before lasing, which is confirmed by experimental results. However, the current density corresponding to the peak efficiency of GaN-based LDs before lasing, Jmax, is nearly 40 A/cm2, which is much lower than that reported by other studies. The reported Jmax, measured from the cavity facet side is modulated by the absorption of quantum wells, which shifts the Jmax to a higher value. In addition, the currents due to various recombinations are calculated. It is found that Auger recombination affects the threshold current greatly, but it only plays a small role at high current injection levels. PMID:28772842

  15. Numerical study of a highly efficient solar cell with graded band gap design

    NASA Astrophysics Data System (ADS)

    Tan, Ming-Hsuan; Tseng, Hung-Ruei; Kuo, Chien-Ting; Hsu, Shun-Chieh; Lo, Yen-Hua; Tsai, Che-Pin; Cheng, Yuh-Jen; Lin, Chien-Chung

    2015-05-01

    A linearly graded band gap design in the intrinsic layer of a p-i-n solar cell is studied numerically. An ideal model using Matlab® is built and the device performance is calculated using continuity equations and an effective band gap model under various band gap combinations. The power conversion efficiency (PCE) can be as high as 30.21%, while the abrupt junction reference device only exhibits 29.25% under the same parameters. This design is also evaluated using the commercial TCAD software APSYS®, and the calculations show optimal efficiency enhancements of about 1.14-fold that of the abrupt junction device in an AlAs/GaAs system and 2.05-fold that in an InGaN/GaN system.

  16. Synthesis and preliminary evaluation of n.c.a. iodoquine: a novel radiotracer with high uptake in cells with high ALDH1 expression.

    PubMed

    Chin, Bennett B; Hjelemand, Anita; Rich, Jeremy; Song, Haijing; Lascola, Christopher; Storms, Robert; McLendon, Roger; Reiman, Robert; Greer, Kim L; Metzler, Scott D; McDougald, Darryl; Dai, Diana; Vaidyanathan, Ganesan

    2012-01-01

    Chloroquine has demonstrated high affinity for aldehyde dehydrogenase 1A1 (ALDH1), an enzyme expressed in the highly tumorigenic CD133+ brain tumor initiating subpopulation. The purpose of this study is to report the novel synthesis of a chloroquine analogue, n.c.a. iodoquine, and the in vitro and in vivo uptake in cells with high ALDH1 content. Iodoquine was synthesized in novel no-carrier-added forms (n.c.a.) for both 125I and 123I. I25I IQ and 18F FDG cell uptake assays were performed in the L1210 and L1210cpa (cyclophosphamide resistant), A549, and MG456 glioblastoma cell lines. Uptake was expressed as a percent of the administered activity. 125I IQ biodistribution studies assessed organ uptake at 1, 4, and 24 hours after IV administration (n= 15 total; 5 mice/timepoint). Radiation dosimetry estimates were calculated using standard OLINDA/EXM software. In vivo imaging of 123I IQ uptake in MG456 glioblastoma mouse model (n=10) was performed with small animal high resolution micro-SPECT. Autoradiography and histology co-localized radiotracer and tumor biodistribution. Uptake in MG456 glioblastoma tumors was quantified with gamma counting. L1210 cpa (high ALDH1) showed significantly higher 125I IQ uptake compared to the parental L1210 (low ALDH1) for all time points through 4 hours (20.7% ± 1.4% versus 11.0% ± 0.5%; 21.3% ± 0.9% versus 11.0% ± 0.4%; 20.6% ± 0.7% versus 9.4% ± 0.3%; and 15.7% ± 0.7% versus 7.5% + 0.4% at 30 minutes, and 1, 2 and 4 hours, respectively; p < 0.001 for all time points). In the CD133+ fraction of MG456 glioblastoma cell line, IQ uptake was significantly higher compared to FDG at all time points through 4 hours (81.5% ± 0.9% versus 1.3% ± 0.1%; 88.8% ± 0.4% versus 1.3% ± 0.1%; 87.8% ± 2.1% versus 1.7% ± 0.2%; and 87.0% ± 2.4% versus 1.8% ± 0.1 at 30 minutes, and 1, 2 and 4 hours, respectively; p > 0.001 for all time points). The A549 lung cancer cell line also showed high IQ uptake through 4 hours. IQ normal

  17. [Efficiency of an alcohol addiction prevention program at the workplace: results of an empirical study].

    PubMed

    Ennenbach, M; Gass, B; Reinecker, H; Soyka, M

    2009-03-01

    Following an anonymous survey on health und substance use problems in 2004, a prevention program for workers at a Bavarian rehabilitation clinic was initiated. Its efficiency was evaluated by a follow-up study in 2007. The initial analysis had indicated a high rate of substance abuse. Young female employees had been identified as one of the risk groups for alcohol consumption and professional discontent. Based on these findings, a special prevention program was established. The follow-up study revealed some improvements with respect to health und substance abuse, including a significant reduction in average alcohol consumption. These findings indicate that prevention programs at the workplace are both possible and effective.

  18. Case studies of energy efficiency financing in the original five pilot states, 1993-1996

    SciTech Connect

    Farhar, B C; Collins, N E; Walsh, R W

    1997-05-01

    The purpose of this report is to document progress in state-level programs in energy efficiency financing programs that are linked with home energy rating systems. Case studies are presented of programs in five states using a federal pilot program to amortize the costs of home energy improvements. The case studies present background information, describe the states` program, list preliminary evaluation data and findings, and discuss problems and solution encountered in the programs. A comparison of experiences in pilot states will be used to provide guidelines for program implementers, federal agencies, and Congress. 5 refs.

  19. Energy Efficiency Feasibility Study and Resulting Plan for the Bay Mills Indian Community

    SciTech Connect

    Kushman, Chris

    2014-02-03

    In 2011 the Inter-Tribal Council of Michigan, Inc. was awarded an Energy Efficiency Development and Deployment in Indian Country grant from the U.S. Department of Energy’s Tribal Energy Program. This grant aimed to study select Bay Mills Indian Community community/government buildings to determine what is required to reduce each building’s energy consumption by 30%. The Bay Mills Indian Community (BMIC) buildings with the largest expected energy use were selected for this study and included the Bay Mills Ellen Marshall Health Center building, Bay Mills Indian Community Administration Building, Bay Mills Community College main campus, Bay Mills Charter School and the Waishkey Community Center buildings. These five sites are the largest energy consuming Community buildings and comprised the study area of this project titled “Energy Efficiency Feasibility Study and Resulting Plan for the Bay Mills Indian Community”. The end objective of this study, plan and the Tribe is to reduce the energy consumption at the Community’s most energy intensive buildings that will, in turn, reduce emissions at the source of energy production, reduce energy expenditures, create long lasting energy conscious practices and positively affect the quality of the natural environment. This project’s feasibility study and resulting plan is intended to act as a guide to the Community’s first step towards planned energy management within its buildings/facilities. It aims to reduce energy consumption by 30% or greater within the subject facilities with an emphasis on energy conservation and efficiency. The energy audits and related power consumption analyses conducted for this study revealed numerous significant energy conservation and efficiency opportunities for all of the subject sites/buildings. In addition, many of the energy conservation measures require no cost and serve to help balance other measures requiring capital investment. Reoccurring deficiencies relating to heating

  20. Energy Efficiency Potential in Existing Commercial Buildings: Review of Selected Recent Studies

    SciTech Connect

    Belzer, David B.

    2009-04-03

    This report reviews six recent studies (from 2002 through 2006) by states and utilities to assess the energy saving potential in existing commercial buildings. The studies cover all or portions of California, Connecticut, Vermont, Colorado, Illinois, and the Pacific Northwest. The studies clearly reveal that lighting remains the single largest and most cost effective end use that can be reduced to save energy. Overall the study indicated that with existing technologies and costs, a reasonable range of economic savings potential in existing commercial buildings is between 10 and 20 percent of current energy use. While not a focus of the study, an additional conclusion is that implementation of commercial building monitoring and controls would also play an important role in the nation’s efforts to improve energy efficiency of existing buildings.

  1. Development of efficient overland flow routing based on recursive algorithms - a case study

    NASA Astrophysics Data System (ADS)

    Huang, Pin-Chun; Lee, KwanTun

    2017-04-01

    Two primary concerns in performing watershed overland flow routing are the numerical instability and computational efficiency. The stability of an explicit scheme is usually restrained by selecting an adequate routing time increment to follow the Courant-Friedrich-Lewy condition and the Hunter condition. The Courant-Friedrich-Lewy condition is adopted to confirm that the numerical marching speed is larger than the wave celerity, and the Hunter condition is used to avoid back-and-forth refluxing between adjacent grids on flat regions, whereas selection of a small time increment following these two conditions has decreased the computational efficiency in performing overland flow routing. This study aims to create a robust algorithm to relax both restrictions simultaneously. The proposed algorithm was first implemented on a 1D overland plane to evaluate the accuracy of the numerical result by comparing it with an analytical solution. Then, the algorithm was further applied to a mountain watershed for 2D runoff simulations. The results show that the proposed integrated algorithm can provide an accurate runoff simulation and achieve satisfactory performance in terms of computational efficiency.

  2. An empirical study on energy efficiency improvement through photovoltaic systems and a LED lighting control system

    NASA Astrophysics Data System (ADS)

    Choi, Young Kwan; Lee, Jae Hyeong

    2015-09-01

    In this research, a facility was constructed and its performance was analyzed to improve the energy efficiency of a vertical-type water treatment building. After the design and construction of a fixed tilt Photovoltaic in Building (PVIB) on the rooftop using a crystalline silicon solar cell module and photovoltaic generator integrated with the building by using a Building Integrated Photovoltaic System (BIPV), a thin-film module on the rooftop and outer wall of water treatment building, and the generation efficiency was analyzed. Also, a DC distribution was established for use of a brushless DC (BLDC) pump motor, and the existing lighting-facility-based manual on-off method was turned into a system for energy conservation by controlling light emitting diode (LED) through a wireless motion sensor and dimming control. In addition, a Building Energy Management System (BEMS) for a real-time analysis of the energy efficiency for a vertical0type water treatment building was prepared and tested. The vertical-type water treatment building developed in this study is currently operating the BEMS. The vertical-type water treatment building reported in this paper is expected to reduce energy consumption by about 30% compared to existing water treatment systems.

  3. Vanadium redox flow battery efficiency and durability studies of sulfonated Diels Alder poly(phenylene)s

    SciTech Connect

    Fujimoto, Cy H.; Kim, Soowhan; Stains, Ronald; Wei, Xiaoliang; Li, Liyu; Yang, Zhenguo

    2012-07-01

    Sulfonated Diels Alder poly(phenylene) (SDAPP) was examined for vanadium redox flow battery (VRFB) use. The ion exchange capacity (IEC) was varied from 1.4, 1.6 and 2.0 meq/g in order to tune the proton conductivity and vanadium permeability. Coulombic efficiencies between 92 to 99% were observed, depending on IEC (lower IEC, higher coulombic efficiencies). In all cases the SDAPP displayed comparable energy efficiencies (88 - 90%) to Nafion 117 (88%) at 50mA/cm2. Membrane durability also was dependent on IEC; SDAPP with the highest IEC lasted slightly over 50 cycles while SDAPP with the lowest IEC lasted over 400 cycles and testing was discontinued only due to time constraints. Accelerated vanadium lifetime studies were initialed with SDAPP, by soaking films in a 0.1 M V5+ and 5.0 M total SO4-2 solution. The rate of degradation was also proportional with IEC; the 2 meq/g sample dissolved within 376 hours, the 1.6 meq/g sample dissolved after 860 hours, while the 1.4 meq/g sample broke apart after 1527 hours.

  4. Study on Equity and Efficiency of Health Resources and Services Based on Key Indicators in China.

    PubMed

    Zhang, Xinyu; Zhao, Lin; Cui, Zhuang; Wang, Yaogang

    2015-01-01

    This study aims to evaluate the dialectical relationship between equity and efficiency of health resource allocation and health service utilization in China. We analyzed the inequity of health resource allocation and health service utilization based on concentration index (CI) and Gini coefficient. Data envelopment analysis (DEA) was used to evaluate the inefficiency of resource allocation and service utilization. Factor Analysis (FA) was used to determine input/output indicators. The CI of Health Institutions, Beds in Health Institutions, Health Professionals and Outpatient Visits were -0.116, -0.012, 0.038, and 0.111, respectively. Gini coefficient for the 31 provinces varied between 0.05 and 0.43; out of these 23 (742%) were observed to be technically efficient constituting the "best practice frontier". The other 8 (25.8%) provinces were technically inefficient. Health professionals and outpatient services are focused on higher income levels, while the Health Institutions and Beds in Health Institutions were concentrated on lower income levels. In China, a few provinces attained a basic balance in both equity and efficiency in terms of current health resource and service utilization, thus serving as a reference standard for other provinces.

  5. A study of the structural efficiency of fluted core graphite-epoxy panels

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.

    1990-01-01

    The structural efficiency of compression-loaded graphite-epoxy sandwich panels with fluted cores is studied to determine their weight saving potential. Graphite-epoxy equilateral triangular elements are used to construct the fluted cores for the sandwich panels. Two panel configurations are considered. One configuration has two layers of triangular elements in the fluted core and the second configuration has only one layer of triangular elements in the core. An optimization code is used to find the minimum weight design for each panel configuration. Laminate ply orientations are limited to approx. 45, 0, and 90 deg. A constraint on the axial stiffness is included in the design process so the panel will conform to typical constraints for aircraft wing structures. Minimum thickness requirements for each laminate and maximum allowable strains are also included. A comparison is made of the calculated structural efficiency of the fluted core panels to the structural efficiency of aluminum transport aircraft structures and simple blade-stiffened graphite-epoxy panels. Limited experimental results are also included for comparison with the analytical predictions and to identify the critical failure mechanisms of graphite-epoxy fluted-core sandwich panels.

  6. Study on Equity and Efficiency of Health Resources and Services Based on Key Indicators in China

    PubMed Central

    Zhang, Xinyu; Zhao, Lin; Cui, Zhuang; Wang, Yaogang

    2015-01-01

    Background This study aims to evaluate the dialectical relationship between equity and efficiency of health resource allocation and health service utilization in China. Methods We analyzed the inequity of health resource allocation and health service utilization based on concentration index (CI) and Gini coefficient. Data envelopment analysis (DEA) was used to evaluate the inefficiency of resource allocation and service utilization. Factor Analysis (FA) was used to determine input/output indicators. Results The CI of Health Institutions, Beds in Health Institutions, Health Professionals and Outpatient Visits were -0.116, -0.012, 0.038, and 0.111, respectively. Gini coefficient for the 31 provinces varied between 0.05 and 0.43; out of these 23 (742%) were observed to be technically efficient constituting the “best practice frontier”. The other 8 (25.8%) provinces were technically inefficient. Conclusions Health professionals and outpatient services are focused on higher income levels, while the Health Institutions and Beds in Health Institutions were concentrated on lower income levels. In China, a few provinces attained a basic balance in both equity and efficiency in terms of current health resource and service utilization, thus serving as a reference standard for other provinces. PMID:26679187

  7. Bioconcentration of the anionic surfactant linear alkylbenzene sulfonate (LAS) in the marine shrimp Palaemonetes varians: a radiotracer study.

    PubMed

    Renaud, Florent; Warnau, Michel; Oberhänsli, François; Teyssié, Jean-Louis; Temara, Ali; Rouleau, Claude; Metian, Marc

    2014-08-15

    Uptake and depuration kinetics of dissolved [(14)C]C₁₂-6-linear alkylbenzene sulfonate (LAS) were determined in the shrimp Palaemonetes varians using environmentally relevant exposure concentration. The shrimp concentrated LAS from seawater with a mean BCF value of 120 L kg(-1) after a 7-day exposure. Uptake biokinetics were best described by a saturation model, with an estimated BCFss, of 159 ± 34 L kg(-1), reached after 11.5 days. Shrimp weight influenced significantly BCF value with smaller individuals presenting higher affinity to LAS. To the light of a whole body autoradiography, major accumulation of LAS occurred in the cephalothorax circulatory system (gills, heart, hepatopancreas) and ocular peduncle, but not in the flesh, limiting potential transfer to human consumers. LAS depuration rate constant value of the shrimp was 1.18 ± 0.08 d(-1) leading to less than 1% of remaining LAS in its tissues after 8 days of depuration.

  8. The Efficiency Analysis of Low Impact Development Applied in Taiwan: A Case Study of Porous Pavement

    NASA Astrophysics Data System (ADS)

    Huang, Y. H.; Liu, H. J.; Hsu, N. S.; Chang, F. M.

    2014-12-01

    Low Impact Development (LID) has been developed since the end of 1990s. Lots of successful experience based on this new technology have been made. Taiwan Executive Yuan is conducting a six-year (2014~2019) program "Integrated River Basin Management Plan" applying LID to build sponge cities. Construction and Planning Agency, Ministry of the Interior is editing the manual of LID technology for Taiwan. However, since the hydrological environments, physiographic conditions, climates, the strength and frequency of disasters in Taiwan are different from that in America, this study takes the first laboratory experiment and model simulation to evaluate the efficiency of application of LID in Taiwan.LID Facilities includes porous pavement, rain garden, green roof, tree box filter facilities and so on, and in this study, porous pavement is taken as an example for discussion. In the part of laboratory experiments, the sand box experiments is designed to operate with the specified rainfall return period calculated by Horton formula and rainfall characteristics of Taipei. Then the outflow hydrograph in each designed rainfall of specified return period can be evaluated. As for model simulation, this study constructs LID simulation elements by SWMM model and tests the suitability for simulation of the outflow hydrograph obtained from experiments, and definitely quantifies the efficiency of water retention and flood reduction of porous pavement. The results fits well with the experimental observation data with less than 10% error of pick flow. It suggests that, with LID simulation elements constructed in this study, the efficiency of LID in actual on-site application can be evaluated.The results shows that porous pavement is able to delay arrival time of pick about 5% ~10% and reduce the pick flow about 5%~20%, and hold the ability of near 3~5% water retention. It proves that application of LID can retain water and reduce flood in Taiwan.

  9. Energy efficient engine program technology benefit/cost study. Volume 1: Executive summary

    SciTech Connect

    Gray, D.E.; Gardner, W.B.

    1983-10-01

    Under the NASA sponsored Energy Efficient Engine Program, Pratt and Whitney completed the Benefit/Cost Study to identify turbofan engine technologies required for the years 2000 to 2010, to assess the benefits of those technologies, and to formulate programs for developing the technologies required for that time period. The results verified that there are still many potential benefits to be realized from the advancement of gas turbine technology. The initial effort was to screen and rank preliminary technology concepts that might be amenable to future development. Cycle studies, flowpath definition studies, and mechanical configuration studies were then used to identify and establish the feasibility of the technologies that would be required in the 2000 to 2010 time frame. These efforts showed that a turbofan engine with advancements in aerodynamics, mechanical arrangements, and materials offered significant performance improvements over 1988 technology. The benefits of the technologies were assessed using fuel burn and direct operating cost plus interest (DOC+I). These concepts could yield thrust specific fuel consumption benefits of almost 16 percent, fuel burn benefits of up to 24 percent and DOC+I benefits of up to 14 percent in a long-range airplane relative to Energy Efficient Engine technology levels. Technology development programs were formulated and recommended to realize those benefits.

  10. Cloud-based preoperative planning for total hip arthroplasty: a study of accuracy, efficiency, and compliance.

    PubMed

    Maratt, Joseph D; Srinivasan, Ramesh C; Dahl, William J; Schilling, Peter L; Urquhart, Andrew G

    2012-08-01

    As digital radiography becomes more prevalent, several systems for digital preoperative planning have become available. The purpose of this study was to evaluate the accuracy and efficiency of an inexpensive, cloud-based digital templating system, which is comparable with acetate templating. However, cloud-based templating is substantially faster and more convenient than acetate templating or locally installed software. Although this is a practical solution for this particular medical application, regulatory changes are necessary before the tremendous advantages of cloud-based storage and computing can be realized in medical research and clinical practice. Copyright 2012, SLACK Incorporated.

  11. A critical study on efficiency of different materials for fluoride removal from aqueous media

    PubMed Central

    2013-01-01

    Fluoride is a persistent and non-biodegradable pollutant that accumulates in soil, plants, wildlife and in human beings. Therefore, knowledge of its removal, using best technique with optimum efficiency is needed. The present survey highlights on efficacy of different materials for the removal of fluoride from water. The most important results of extensive studies on various key factors (pH, agitation time, initial fluoride concentration, temperature, particle size, surface area, presence and nature of counter ions and solvent dose) fluctuate fluoride removal capacity of materials are reviewed. PMID:23497619

  12. Operationally Efficient Propulsion System Study (OEPSS) data book. Volume 2: Ground operations problems

    NASA Technical Reports Server (NTRS)

    Waldrop, Glen S.

    1990-01-01

    Operations problems and cost drivers were identified for current propulsion systems and design and technology approaches were identified to increase the operational efficiency and to reduce operations costs for future propulsion systems. To provide readily usable data for the ALS program, the results of the OEPSS study were organized into a series of OEPSS Data Books. This volume presents a detailed description of 25 major problems encountered during launch processing of current expendable and reusable launch vehicles. A concise description of each problem and its operational impact on launch processing is presented, along with potential solutions and technology recommendation.

  13. A systematic study of antibacterial silver nanoparticles: efficiency, enhanced permeability, and cytotoxic effects

    NASA Astrophysics Data System (ADS)

    Azócar, Manuel I.; Tamayo, Laura; Vejar, Nelson; Gómez, Grace; Zhou, Xiangrong; Thompsom, George; Cerda, Enrique; Kogan, Marcelo J.; Salas, Edison; Paez, Maritza A.

    2014-09-01

    We report here a systematic study of the antibacterial behavior of silver nanoparticles coated with fatty acids (oleic: AgNP-O, linoleic: AgNP-L, and palmitic acids: AgNP-P) in water. We have found remarkable differences in their capability to penetrate bacteria cell over a broader range of particle size of 4-96 nm compared to previously reported work, and a variable toxicity depending on the particles size. Our results indicate that silver nanoparticles stabilized with oleic acid showed clear advantages in antibacterial activity, penetration inside the bacteria cells, cytotoxicity, time effectiveness, efficiency, and stability against light.

  14. Optimization and modeling studies for obtaining high injection efficiency at the Advanced Photon Source.

    SciTech Connect

    Emery, L.; APS Operations Division

    2005-01-01

    In recent years, the optics of the Advanced Photon Source storage ring has evolved to a lower equilibrium emittance (2.5 nm-rad) at the cost of stronger sextupoles and stronger nonlinearities, which have reduced the injection efficiency from the virtual 100% of the high emittance mode. Over the years we have developed a series of optimizations, measurements, and modeling studies of the injection process, which allows us to obtain or maintain low injection losses. The above will be described along with the injection configuration.

  15. Case studies in making assessment efficient while developing student professionalism and managing transition

    NASA Astrophysics Data System (ADS)

    Rossiter, J. A.

    2013-12-01

    It is known that assessment drives learning and hence a good assessment design is key to effective student development. This paper gives some case studies in effective assessment strategies within engineering. The main contribution is to demonstrate how one can simultaneously meet a number of requirements with individual assessments and therefore be efficient in both the student and staff assessment load. The paper also proposes that assessments should be challenging and the benefits of expecting students to rise to this challenge and also how one can meet many independent learning objectives in a single assignment in order to manage the overall assessment load for staff and students.

  16. Cellular metabolic responses of PET radiotracers to (188)Re radiation in an MCF7 cell line containing dominant-negative mutant p53.

    PubMed

    Cheon, Gi Jeong; Chung, Hye-Kyung; Choi, Jung-A; Lee, Su-Jae; Ahn, Soon-Hyuk; Lee, Tae-Sup; Choi, Chang Woon; Lim, Sang Moo

    2007-05-01

    We investigated the relations between the cell uptakes of metabolic radiotracers and beta-radiation pretreatment using a dominant mutant p53 (p53mt) cell line to evaluate the effects of p53 genes on (18)F labeled positron emission tomography (PET) radiotracer uptakes. pCMV-Neo-Bam (control), which contains a neo-resistance marker, and p53 dominant-negative mutant expression constructs were stably transfected into MCF7 cell line. Cells were plated in 24-well plates at 1.0x10(5) cells for 18 h. Rhenium-188 ((188)Re) (a beta emitter) was added to the medium (3.7, 18.5, 37 MBq) and incubated for 24 h. We performed gamma-counting to determine the cellular uptakes of 2-[(18)F]fluoro-2-deoxy-d-glucose (FDG), o-(2-[(18)F]fluoroethyl)-l-tyrosine (FET) and 2'-[(18)F]fluoro-2'-deoxythymidine (FLT) (370 kBq, 60 min). Cell viabilities were determined by trypan blue staining and flow cytometry. p53mt cells showed 1.5-2-fold higher FDG uptake than wild-type p53 cells in basal condition, and the difference of FDG uptake was greater after (188)Re treatment (P<.01). FET uptake increased with (188)Re dose without a significant difference between p53 statuses. p53mt cells showed lower FLT uptake than wild-type p53 cells in basal condition, and the difference of FLT uptake was greater after (188)Re treatment. By cell viability testing and FACS analysis, p53mt cells showed lower viability and a larger apoptotic fraction (sub-G1) than wild-type p53 cells after (188)Re treatment. We speculate that p53 dysfunction increases glucose and decreases thymidine metabolism in cancer cells and that this may be exaggerated by (188)Re beta-radiation. Our findings suggest that FDG could reflect tumor viability and malignant potential after (188)Re beta-radiation treatment, whereas FLT could be a more useful PET radiotracer for assessing therapeutic response to beta-radiation, especially in cancer cells with an altered function of p53.

  17. A parametric study of thrust and efficiency of an oscillating airfoil

    NASA Astrophysics Data System (ADS)

    Mackowski, A. W.; Williamson, C. H. K.

    2012-11-01

    An oscillating airfoil serves as a classic test case for a variety of unsteady phenomena in fluid mechanics. In nature, fish, birds, and insects oscillate their fins and wings to produce thrust and maneuvering forces, often studied by approximating the appendages as airfoils. On the other hand, the unsteady fluid mechanics of an oscillating airfoil involve vortex shedding and vortex advection, which are essential to understanding unsteady thrust, and worth studying in their own right. This information is useful in areas such as flow control, fluid-structure interaction, and undersea robotics. In this work, we examine the thrust and efficiency of a heaving (or pitching) foil as a function of variables such as the reduced frequency and amplitude (noting previous related studies such as Koochesfahani 1989; Anderson et al. 1998). Further, our novel experimental ``cyber-physical'' technique [Mackowski & Williamson, 2011] allows the airfoil to propel itself under its own thrust. Our experimental apparatus constantly monitors the fluid forces acting on the foil, and commands velocity to a carriage system in accordance with these forces. With this capability, we are able to measure the terminal velocity of a self-propelled airfoil, as well as its stationary thrust and efficiency.

  18. Analytical and experimental study of structurally efficient composite hat-stiffened panels loaded in axial compression

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Mikulas, M. M., Jr.

    1975-01-01

    Structural efficiency studies were made to determine the weight-saving potential of graphite/epoxy composite structures for compression panel applications. Minimum-weight hat-stiffened and open-corrugation configurations were synthesized using a nonlinear mathematical programing technique. Selected configurations were built and tested to study local and Euler buckling characteristics. Test results for 23 panels critical in local buckling and six panels critical in Euler buckling are compared with analytical results obtained using the BUCLASP-2 branched plate buckling program. A weight efficiency comparison is made between composite and aluminum compression panels using metal test data generated by the NACA. Theoretical studies indicate that potential weight savings of up to 50% are possible for composite hat-stiffened panels when compared with similar aluminum designs. Weight savings of 32% to 42% were experimentally achieved. Experience to date suggests that most of the theoretical weight-saving potential is available if design deficiencies are eliminated and strict fabrication control is exercised.

  19. Analytical and experimental study of structurally efficient composite hat-stiffened panels loaded in axial compression

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Mikulas, M. M., Jr.

    1975-01-01

    Structural efficiency studies were made to determine the weight-saving potential of graphite/epoxy composite structures for compression panel applications. Minimum-weight hat-stiffened and open-corrugation configurations were synthesized using a nonlinear mathematical programing technique. Selected configurations were built and tested to study local and Euler buckling characteristics. Test results for 23 panels critical in local buckling and six panels critical in Euler buckling are compared with analytical results obtained using the BUCLASP-2 branched plate buckling program. A weight efficiency comparison is made between composite and aluminum compression panels using metal test data generated by the NACA. Theoretical studies indicate that potential weight savings of up to 50% are possible for composite hat-stiffened panels when compared with similar aluminum designs. Weight savings of 32% to 42% were experimentally achieved. Experience to date suggests that most of the theoretical weight-saving potential is available if design deficiencies are eliminated and strict fabrication control is exercised.

  20. Study of the trigger efficiency for SeaQuest Drell-Yan Dimuons

    NASA Astrophysics Data System (ADS)

    Xi, Zhaojia; E906/SeaQuest Collaboration

    2017-01-01

    The SeaQuest (E906) experiment, using the 120 GeV proton beam from the Main Injector at the Fermi National Accelerator Laboratory (FNAL), is studying the quark and antiquark structure of the nucleon using the Drell-Yan process. SeaQuest uses a two magnet focusing spectrometer with four detector stations that include fast plastic scintillator hodoscope planes. The hodoscope arrays along with Field Programmable Gate Arrays(FPGAs) are used to make the SeaQuest trigger system. It is designed to measure events with dimuon pairs from the Drell-Yan process. The signals from each hodoscope, which have adequate timing resolution to determine which 18.9 ns beam pulse the event occurred, are sent to the FPGA trigger modules. In order to get a correct hit pattern, each channel is aligned to the beam RF clock. The trigger is formed when the hits fulfill a dimuon pattern. A program has been developed to analyze and calculate trigger efficiency by using data from hodoscopes. It is important to study trigger efficiency to be used in physics results, such as the cross section of the Drell-Yan process. The method, programming, measurements, and results of this study will be presented. This research was supported by US DOE MENP Grant DE-FG02-03ER41243.

  1. Spectroscopic and structural studies of energetically efficient transport in nanocontacts to NiSi nanowires

    NASA Astrophysics Data System (ADS)

    Stein, A.; Farhat, I. A. H.; Lacevic, N.; Bazuhair, S. K.; Azhar, S. S.; Isakovic, A. F.

    Understanding correlations between mechanical, thermal, structural and electronic transport properties of different nanocontact geometries to nanowires, such as Au/Cu-NiSi-Si, remain one of the major goals of nanodevices reliability and scalability research. Aiming to clarify the failure modes and processes that affect the energy efficiency of transport and switching in constrained nanocontact geometries, such as end contacts, we conducted the structural, spectroscopic, and noise correlation studies. We show how the spatial (in)homogeneity at and in the near vicinity of the interface affects the transport performance of the nanojunctions. Mobile Ni clusters are identified at the nanojunction interface via Raman spectromicroscopy and their influence on charge transport is analyzed. We also show that the noise correlation spectra and micro-X-ray stress-strain studies in the nanojunctions are effictive tools in predicting the energy efficiency of the nanojunctions. A computational study of the interfacial properties of metal/Ni-Si via DFT and MD simulations is implemented. Work supported by Mubadala-SRC # 2011-KJ-2190. A part of the work done at BNL-CFN, supported by DOE. A part of the work done at Cornell Univ.CFN and CCMR, supported by the NSF.

  2. Study of the trigger efficiency for SeaQuest Drell-Yan Dimuons

    NASA Astrophysics Data System (ADS)

    Xi, Zhaojia; SeaQuest/E906 Collaboration

    2016-09-01

    The SeaQuest (E906) experiment, using the 120 GeV proton beam from the Main Injector at the Fermi National Accelerator Laboratory (FNAL), is studying the quark and antiquark structure of the nucleon using the Drell-Yan process. SeaQuest uses a two magnet focusing spectrometer with four detector stations that include fast plastic scintillator hodoscope planes. The hodoscope arrays along with Field Programmable Gate Arrays(FPGAs) are used to make the SeaQuest trigger system. It is designed to measure events with dimuon pairs from the Drell-Yan process. The signals from each hodoscope, which have adequate timing resolution to determine which 18.9 ns beam pulse the event occurred, are sent to the FPGA trigger modules. In order to get a correct hit pattern, each channel is aligned to the beam RF clock. The trigger is formed when the hits fulfill a dimuon pattern. A program has been developed to analyze and calculate trigger efficiency by using data from hodoscopes. It is important to study trigger efficiency to be used in physics results, such as the cross section of the Drell-Yan process. The method, programming, measurements, and results of this study will be presented. This research was supported by US DOE MENP Grant DE-FG02-03ER41243.

  3. Operationally Efficient Propulsion System Study (OEPSS) data book. Volume 1: Generic ground operations data

    NASA Technical Reports Server (NTRS)

    Byrd, Raymond J.

    1990-01-01

    This study was initiated to identify operations problems and cost drivers for current propulsion systems and to identify technology and design approaches to increase the operational efficiency and reduce operations costs for future propulsion systems. To provide readily usable data for the Advance Launch System (ALS) program, the results of the Operationally Efficient Propulsion System Study (OEPSS) were organized into a series of OEPSS Data Books as follows: Volume 1, Generic Ground Operations Data; Volume 2, Ground Operations Problems; Volume 3, Operations Technology; Volume 4, OEPSS Design Concepts; and Volume 5, OEPSS Final Review Briefing, which summarizes the activities and results of the study. This volume presents ground processing data for a generic LOX/LH2 booster and core propulsion system based on current STS experience. The data presented includes: top logic diagram, process flow, activities bar-chart, loaded timelines, manpower requirements in terms of duration, headcount and skill mix per operations and maintenance instruction (OMI), and critical path tasks and durations.

  4. Study on surface-enhanced Raman scattering efficiency of Ag core-Au shell bimetallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Dong, Xiao; Gu, Huaimin; Kang, Jian; Yuan, Xiaojuan

    2009-08-01

    In this article, the relationship between the states of Ag core-Au shell (core-shell) nanoparticles (NP) and the intensity of Raman scattering of analytes dissolved in the water and adsorbed on the NP was studied. The core-shell NP were synthesised by coating Au layers over Ag seeds by the method of "seed-growth". To highlight the advantage of the core-shell NP, Ag colloid and Au colloid were chosen for contrasting. The analyte that were chosen for this testing were methylene blue (MB) for the reason that MB has very strong signal in surface-enhanced Raman scattering (SERS). The SERS activity of optimalizing states of Ag and Au colloids were compared with that of core-shell NP when MB was used as analyte. In this study, sodium chloride, sodium sulfate and sodium nitrate were used as aggregating agents for Ag, Au colloids and core-shell NP, because anions have a strong influence on the SERS efficiency and the stability of colloids. The results indicate that core-shell NP can obviously enhance the SERS of MB. The aim of this study is to prove that compared with the metal colloid, the core-shell NP is a high efficiency SERS active substrate.

  5. Efficient Estimation of Semiparametric Transformation Models for Two-Phase Cohort Studies

    PubMed Central

    ZENG, DONGLIN; LIN, D. Y.

    2013-01-01

    Under two-phase cohort designs, such as case-cohort and nested case-control sampling, information on observed event times, event indicators, and inexpensive covariates is collected in the first phase, and the first-phase information is used to select subjects for measurements of expensive covariates in the second phase; inexpensive covariates are also used in the data analysis to control for confounding and to evaluate interactions. This paper provides efficient estimation of semiparametric transformation models for such designs, accommodating both discrete and continuous covariates and allowing inexpensive and expensive covariates to be correlated. The estimation is based on the maximization of a modified nonparametric likelihood function through a generalization of the expectation-maximization algorithm. The resulting estimators are shown to be consistent, asymptotically normal and asymptotically efficient with easily estimated variances. Simulation studies demonstrate that the asymptotic approximations are accurate in practical situations. Empirical data from Wilms’ tumor studies and the Atherosclerosis Risk in Communities (ARIC) study are presented. PMID:24659837

  6. Efficient removal of endosulfan from aqueous solution by UV-C/peroxides: a comparative study.

    PubMed

    Shah, Noor S; He, Xuexiang; Khan, Hasan M; Khan, Javed Ali; O'Shea, Kevin E; Boccelli, Dominic L; Dionysiou, Dionysios D

    2013-12-15

    This study explored the efficiency of UV-C-based advanced oxidation processes (AOPs), i.e., UV/S2O8(2-), UV/HSO5(-), and UV/H2O2 for the degradation of endosulfan, an organochlorine insecticide and an emerging water pollutant. A significant removal, 91%, 86%, and 64%, of endosulfan, at an initial concentration of 2.45 μM and UV fluence of 480 mJ/cm(2), was achieved by UV/S2O8(2-), UV/HSO5(-), and UV/H2O2 processes, respectively, at a [peroxide]0/[endosulfan]0 molar ratio of 20. The efficiency of these processes was, however, inhibited in the presence of radical scavengers, such as alcohols (e.g., tertiary butyl alcohol and isopropyl alcohol) and natural organic matter (NOM). The inhibition was also influenced by common inorganic anions in the order of nitrite > bicarbonate > chloride > nitrate ≈ sulfate. The observed pseudo-first-order rate constant decreased while the degradation rate increased with increasing initial concentration of the target contaminant. The degradation mechanism of endosulfan by the AOPs was evaluated revealing the main by-product as endosulfan ether. Results of this study suggest that UV-C-based AOPs are potential methods for the removal of pesticides, such as endosulfan and its by-products, from contaminated water.

  7. Internalizing and externalizing traits predict changes in sleep efficiency in emerging adulthood: an actigraphy study

    PubMed Central

    Yaugher, Ashley C.; Alexander, Gerianne M.

    2015-01-01

    Research on psychopathology and experimental studies of sleep restriction support a relationship between sleep disruption and both internalizing and externalizing disorders. The objective of the current study was to extend this research by examining sleep, impulsivity, antisocial personality traits, and internalizing traits in a university sample. Three hundred and eighty six individuals (161 males) between the ages of 18 and 27 years (M = 18.59, SD = 0.98) wore actigraphs for 7 days and completed established measures of disorder-linked personality traits and sleep quality (i.e., Personality Assessment Inventory (PAI), Triarchic Psychopathy Measure, Barratt Impulsiveness Scale-11, and the Pittsburgh Sleep Quality Index). As expected, sleep measures and questionnaire scores fell within the normal range of values and sex differences in sleep and personality were consistent with previous research results. Similar to findings in predominantly male forensic psychiatric settings, higher levels of impulsivity predicted poorer subjective sleep quality in both women and men. Consistent with well-established associations between depression and sleep, higher levels of depression in both sexes predicted poorer subjective sleep quality. Bidirectional analyses showed that better sleep efficiency decreases depression. Finally, moderation analyses showed that gender does have a primary role in sleep efficiency and marginal effects were found. The observed relations between sleep and personality traits in a typical university sample add to converging evidence of the relationship between sleep and psychopathology and may inform our understanding of the development of psychopathology in young adulthood. PMID:26500575

  8. The human component of sustainability: a study for assessing "human performances" of energy efficient construction blocks.

    PubMed

    Attaianese, Erminia; Duca, Gabriella

    2012-01-01

    This paper presents an applied research aimed at understanding the relevance and the applicability of human related criteria in sustainability assessment of construction materials. Under a theoretical perspective, human factors consideration is strongly encouraged by building sustainability assessment methods, but the practice demonstrates that current models for building sustainability assessment neglect ergonomic issues, especially those ones concerning the construction phase. The study starts from the observation that new construction techniques for high energy efficient external walls are characterized by elements generally heavier and bigger than traditional materials. In this case, high sustainability performances connected with energy saving could be reached only consuming high, and then not very much sustainable, human efforts during setting-up operations. The paper illustrates a practical approach for encompassing human factors in sustainability assessment of four block types for energy efficient external walls. Research steps, from block selections to bricklaying task analysis, human factors indicators and metrics formulation, data gathering and final assessment are going to be presented. Finally, open issues and further possible generalizations from the particular case study will be discussed.

  9. The Study of Phosphors Efficiency and Homogeneity using a Nuclear Microprobe

    SciTech Connect

    YANG,C.; DOYLE,BARNEY L.; NIGAM,M.; EL BOUANANI,M.; DUGGAN,J.L.; MCDANIEL,F.D.

    2000-12-08

    Ion Beam Induced Luminescence (IBIL) and Ion Beam Induced Charge Collection (IBICC) have been applied in the study of the luminescence emission efficiency and investigation of the homogeneity of the luminescence emission in phosphors. The IBIL imaging was performed by using sharply focused ion beams or broad/partially-focused ion beams. The luminescence emission homogeneity in samples was examined to reveal possible distributed crystal-defects that may lead to the inhomogeneity of the luminescence emission in samples.The purpose of the study is to search for suitable luminescent thin films that have high homogeneity of luminescence emission, large IBIL efficiency under heavy ion excitation, and can be placed as a thin layer on the top of microelectronic devices to be analyzed with Ion Photon Emission Microscopy (IPEM). The emission yield was found to be low for organic materials, due to saturation of the light output dependence on the energy deposition of heavy ions. The emission yield of a typical Bicron plastic scintillator is about 70 photons/ion/micron. Inorganic materials may have higher IBIL yield under high-energy and heavy-ion excitation, but the challenging problem is the inhomogeneity of the IBIL emission. The IBIL image techniques are applied in the investigation of the homogeneity of a GaN epitaxial thin film, a zircon single crystal and a thin layer coated by Thiogallate(EuII) ceramic.

  10. Density Functional Theory and Electrochemical Studies: Structure-Efficiency Relationship on Corrosion Inhibition.

    PubMed

    Camacho-Mendoza, Rosa L; Gutiérrez-Moreno, Evelin; Guzmán-Percástegui, Edmundo; Aquino-Torres, Eliazar; Cruz-Borbolla, Julián; Rodríguez-Ávila, José A; Alvarado-Rodríguez, José G; Olvera-Neria, Oscar; Thangarasu, Pandiyan; Medina-Franco, José L

    2015-11-23

    The relationship between structure and corrosion inhibition of a series of 30 imidazol, benzimidazol, and pyridine derivatives has been established through the investigation of quantum descriptors calculated with PBE/6-311++G**. A quantitative structure-property relationship model was obtained by examination of these descriptors using a genetic functional approximation method based on a multiple linear regression analysis. Our results indicate that the efficiency of corrosion inhibitors is strongly associated with aromaticity, electron donor ability, and molecular volume descriptors. In order to calibrate and validate the proposed model, we performed electrochemical impedance spectroscopy (EIS) studies on imidazole, 2-methylimidazole, benzimidazole, 2-chloromethylbenzimidazole, pyridine, and 2-aminopyridine compounds. The experimental values for efficiency of corrosion inhibition are in good agreement with the estimated values obtained by our model, thus confirming that our approach represents a promising and suitable tool to predict the inhibition of corrosion attributes of nitrogen containing heterocyclic compounds. The adsorption behavior of imidazole or benzimidazole heterocyclic molecules on the Fe(110) surface was also studied to elucidate the inhibition mechanism; the aromaticity played an important role in the adsorbate-surface complex.

  11. [Studies of marker screening efficiency and corresponding influencing factors in QTL composite interval mapping].

    PubMed

    Gao, Yong-Ming; Wan, Ping

    2002-06-01

    Screening markers efficiently is the foundation of mapping QTLs by composite interval mapping. Main and interaction markers distinguished, besides using background control for genetic variation, could also be used to construct intervals of two-way searching for mapping QTLs with epistasis, which can save a lot of calculation time. Therefore, the efficiency of marker screening would affect power and precision of QTL mapping. A doubled haploid population with 200 individuals and 5 chromosomes was constructed, with 50 markers evenly distributed at 10 cM space. Among a total of 6 QTLs, one was placed on chromosome I, two linked on chromosome II, and the other three linked on chromosome IV. QTL setting included additive effects and epistatic effects of additive x additive, the corresponding QTL interaction effects were set if data were collected under multiple environments. The heritability was assumed to be 0.5 if no special declaration. The power of marker screening by stepwise regression, forward regression, and three methods for random effect prediction, e.g. best linear unbiased prediction (BLUP), linear unbiased prediction (LUP) and adjusted unbiased prediction (AUP), was studied and compared through 100 Monte Carlo simulations. The results indicated that the marker screening power by stepwise regression at 0.1, 0.05 and 0.01 significant level changed from 2% to 68%, the power changed from 2% to 72% by forward regression. The larger the QTL effects, the higher the marker screening power. While the power of marker screening by three random effect prediction was very low, the maximum was only 13%. That suggested that regression methods were much better than those by using the approaches of random effect prediction to identify efficient markers flanking QTLs, and forward selection method was more simple and efficient. The results of simulation study on heritability showed that heightening of both general heritability and interaction heritability of genotype x

  12. Measuring Efficiency of Knowledge Production in Health Research Centers Using Data Envelopment Analysis (DEA): A Case Study in Iran.

    PubMed

    Amiri, Mohammad Meskarpour; Nasiri, Taha; Saadat, Seyed Hassan; Anabad, Hosein Amini; Ardakan, Payman Mahboobi

    2016-11-01

    Efficiency analysis is necessary in order to avoid waste of materials, energy, effort, money, and time during scientific research. Therefore, analyzing efficiency of knowledge production in health areas is necessary, especially for developing and in-transition countries. As the first step in this field, the aim of this study was the analysis of selected health research center efficiency using data envelopment analysis (DEA). This retrospective and applied study was conducted in 2015 using input and output data of 16 health research centers affiliated with a health sciences university in Iran during 2010-2014. The technical efficiency of health research centers was evaluated based on three basic data envelopment analysis (DEA) models: input-oriented, output-oriented, and hyperbolic-oriented. The input and output data of each health research center for years 2010-2014 were collected from the Iran Ministry of Health and Medical Education (MOHE) profile and analyzed by R software. The mean efficiency score in input-oriented, output-oriented, and hyperbolic-oriented models was 0.781, 0.671, and 0.798, respectively. Based on results of the study, half of the health research centers are operating below full efficiency, and about one-third of them are operating under the average efficiency level. There is also a large gap between health research center efficiency relative to each other. It is necessary for health research centers to improve their efficiency in knowledge production through better management of available resources. The higher level of efficiency in a significant number of health research centers is achievable through more efficient management of human resources and capital. Further research is needed to measure and follow the efficiency of knowledge production by health research centers around the world and over a period of time.

  13. Measuring Efficiency of Knowledge Production in Health Research Centers Using Data Envelopment Analysis (DEA): A Case Study in Iran

    PubMed Central

    Amiri, Mohammad Meskarpour; Nasiri, Taha; Saadat, Seyed Hassan; Anabad, Hosein Amini; Ardakan, Payman Mahboobi

    2016-01-01

    Introduction Efficiency analysis is necessary in order to avoid waste of materials, energy, effort, money, and time during scientific research. Therefore, analyzing efficiency of knowledge production in health areas is necessary, especially for developing and in-transition countries. As the first step in this field, the aim of this study was the analysis of selected health research center efficiency using data envelopment analysis (DEA). Methods This retrospective and applied study was conducted in 2015 using input and output data of 16 health research centers affiliated with a health sciences university in Iran during 2010–2014. The technical efficiency of health research centers was evaluated based on three basic data envelopment analysis (DEA) models: input-oriented, output-oriented, and hyperbolic-oriented. The input and output data of each health research center for years 2010–2014 were collected from the Iran Ministry of Health and Medical Education (MOHE) profile and analyzed by R software. Results The mean efficiency score in input-oriented, output-oriented, and hyperbolic-oriented models was 0.781, 0.671, and 0.798, respectively. Based on results of the study, half of the health research centers are operating below full efficiency, and about one-third of them are operating under the average efficiency level. There is also a large gap between health research center efficiency relative to each other. Conclusion It is necessary for health research centers to improve their efficiency in knowledge production through better management of available resources. The higher level of efficiency in a significant number of health research centers is achievable through more efficient management of human resources and capital. Further research is needed to measure and follow the efficiency of knowledge production by health research centers around the world and over a period of time. PMID:28344756

  14. Inappropriate Intra-cervical Injection of Radiotracer for Sentinel Lymph Node Mapping in a Uterine Cervix Cancer Patient: Importance of Lymphoscintigraphy and Blue Dye Injection.

    PubMed

    Kadkhodayan, Sima; Farahabadi, Elham Hosseini; Yousefi, Zohreh; Hasanzadeh, Malihe; Sadeghi, Ramin

    2014-01-01

    Herein, we report a case of sentinel lymph node mapping in a uterine cervix cancer patient, referring to the nuclear medicine department of our institute. Lymphoscintigraphy images showed inappropriate intra-cervical injection of radiotracer. Blue dye technique was applied for sentinel lymph node mapping, using intra-cervical injection of methylene blue. Two blue/cold sentinel lymph nodes, with no pathological involvement, were intra-operatively identified, and the patient was spared pelvic lymph node dissection. The present case underscores the importance of lymphoscintigraphy imaging in sentinel lymph node mapping and demonstrates the added value of blue dye injection in selected patients. It is suggested that pre-operative lymphoscintigraphy imaging be considered as an integral part of sentinel lymph node mapping in surgical oncology. Detailed results of lymphoscintigraphy images should be provided for surgeons prior to surgery, and in case the sentinel lymph nodes are not visualized, use of blue dye for sentinel node mapping should be encouraged.

  15. Synthesis and biological evaluation of positron emission tomography radiotracers targeting serotonin 4 receptors in brain: [18F]MNI-698 and [18F]MNI-699.

    PubMed

    Caillé, Fabien; Morley, Thomas J; Tavares, Adriana Alexandre S; Papin, Caroline; Twardy, Nicole M; Alagille, David; Lee, H Sharon; Baldwin, Ronald M; Seibyl, John P; Barret, Olivier; Tamagnan, Gilles D

    2013-12-01

    Two new benzodioxane derivatives were synthesized as candidates to image the serotonin 4 receptors by positron emission tomography (PET) and radiolabeled with fluorine-18 via a two-step procedure. Competition binding assays demonstrated that MNI-698 and MNI-699 had sub-nanomolar binding affinities against rat striatal 5-HT4 receptors (Ki of 0.20 and 0.07 nM, respectively). PET imaging in rhesus monkey showed that the regional brain distribution of [(18)F]MNI-698 and [(18)F]MNI-699 were consistent with the known densities of 5-HT4 in brain. [(18)F]MNI-698 and [(18)F]MNI-699 are among the first fluorine-18 radiotracers developed for imaging the 5-HT4 receptors in vivo and are currently under preclinical investigation in primates for future human use.

  16. Axial dispersion, holdup and slip velocity of dispersed phase in a pulsed sieve plate extraction column by radiotracer residence time distribution analysis.

    PubMed

    Din, Ghiyas Ud; Chughtai, Imran Rafiq; Inayat, Mansoor Hameed; Khan, Iqbal Hussain

    2008-12-01

    Axial dispersion, holdup and slip velocity of dispersed phase have been investigated for a range of dispersed and continuous phase superficial velocities in a pulsed sieve plate extraction column using radiotracer residence time distribution (RTD) analysis. Axial dispersion model (ADM) was used to simulate the hydrodynamics of the system. It has been observed that increase in dispersed phase superficial velocity results in a decrease in its axial dispersion and increase in its slip velocity while its holdup increases till a maximum asymptotic value is achieved. An increase in superficial velocity of continuous phase increases the axial dispersion and holdup of dispersed phase until a maximum value is obtained, while slip velocity of dispersed phase is found to decrease in the beginning and then it increases with increase in superficial velocity of continuous phase.

  17. Enzyme-immobilized reactors for rapid and efficient sample preparation in MS-based proteomic studies.

    PubMed

    Yamaguchi, Hiroshi; Miyazaki, Masaya

    2013-02-01

    Proteolysis is a key step in proteomic studies integrated with MS analysis but the conventional method of in-solution digestion is limited by time-consuming procedures and low sensitivity. Furthermore, obtaining reliable peptide maps and meaningful sequence data using MS analysis requires not only the separation of the digested peptides but also strictly defined proteolysis conditions. Recently, various immobilized-enzyme reactors have been developed for highly efficient proteolysis in MS-based proteomic analysis. This review focuses on the proteolysis step using protease-immobilized reactors and rapid analysis of protein sequences. We describe the preparation of enzyme reactors by several techniques and protein digestion under unusual conditions. Analysis of posttranslational modifications by enzyme reactors prepared using our immobilization method is presented as a model application. Analysis systems using immobilized-enzyme reactors are expected to become useful tools for proteomic studies and diverse applications in biotechnology.

  18. Automated reporting of pharmacokinetic study results: gaining efficiency downstream from the laboratory.

    PubMed

    Schaefer, Peter

    2011-07-01

    The purpose of bioanalysis in the pharmaceutical industry is to provide 'raw' data about the concentration of a drug candidate and its metabolites as input for studies of drug properties such as pharmacokinetic (PK), toxicokinetic, bioavailability/bioequivalence and other studies. Building a seamless workflow from the laboratory to final reports is an ongoing challenge for IT groups and users alike. In such a workflow, PK automation can provide companies with the means to vastly increase the productivity of their scientific staff while improving the quality and consistency of their reports on PK analyses. This report presents the concept and benefits of PK automation and discuss which features of an automated reporting workflow should be translated into software requirements that pharmaceutical companies can use to select or build an efficient and effective PK automation solution that best meets their needs.

  19. Operationally Efficient Propulsion System Study (OEPSS) data book. Volume 4: OEPSS design concepts

    NASA Technical Reports Server (NTRS)

    Wong, George S.; Ziese, James M.; Farhangi, Shahram

    1990-01-01

    This study was initiated to identify operations problems and cost drivers for current propulsion systems and to identify technology and design approaches to increase the operational efficiency and reduce operations costs for future propulsion systems. To provide readily usable data for the Advanced Launch System (ALS) program, the results of the OEPSS study have been organized into a series of OEPSS Data Books. This volume describes three propulsion concepts that will simplify the propulsion system design and significantly reduce operational requirements. The concepts include: (1) a fully integrated, booster propulsion module concept for the ALS that avoids the complex system created by using autonomous engines with numerous artificial interfaces; (2) an LOX tank aft concept which avoids potentially dangerous geysering in long LOX propellant lines; and (3) an air augmented, rocket engine nozzle afterburning propulsion concept that will significantly reduce LOX propellant requirements, reduce vehicle size and simplify ground operations and ground support equipment and facilities.

  20. Experimental study of the thermal-acoustic efficiency in a long turbulent diffusion-flame burner

    NASA Technical Reports Server (NTRS)

    Mahan, J. R.

    1983-01-01

    A two-year study of noise production in a long tubular burner is described. The research was motivated by an interest in understanding and eventually reducing core noise in gas turbine engines. The general approach is to employ an acoustic source/propagation model to interpret the sound pressure spectrum in the acoustic far field of the burner in terms of the source spectrum that must have produced it. In the model the sources are assumed to be due uniquely to the unsteady component of combustion heat release; thus only direct combustion-noise is considered. The source spectrum is then the variation with frequency of the thermal-acoustic efficiency, defined as the fraction of combustion heat release which is converted into acoustic energy at a given frequency. The thrust of the research was to study the variation of the source spectrum with the design and operating parameters of the burner.

  1. Presence of a highly efficient binding to bacterial contamination can distort data from binding studies

    SciTech Connect

    Balcar, V.J. )

    1990-12-01

    {sup 3}HGABA at low concentrations (5-10 nM) was bound by what appeared to be a GABA receptor binding site in bacterial contamination originating from a batch of distilled water. Under experimental conditions similar to those usually employed in {sup 3}HGABA binding studies, the apparent binding displayed a very high specific component and a high efficiency in terms of {sup 3}HGABA bound per mg of protein. The binding was blocked by muscimol but not by isoguvacine, SR95531 and nipecotic acid. These characteristics suggest that the presence of such spurious binding in the experiments using 3H-labeled ligands in brain homogenates may not always be very obvious and, moreover, it can result in subtle, but serious, distortions of data from such studies, which may not be immediately recognized.

  2. Sleep efficiency during sleep studies: results of a prospective study comparing home-based and in-hospital polysomnography.

    PubMed

    Bruyneel, Marie; Sanida, Christina; Art, Geneviève; Libert, Walter; Cuvelier, Laurent; Paesmans, Marianne; Sergysels, Roger; Ninane, Vincent

    2011-03-01

    To date, the clinical use of unattended home-based polysomnography (PSG) is not recommended. To assess whether sleep efficiency is better at home, we have performed a prospective, crossover, single-blind study comparing unattended home- versus attended in-hospital PSG in a population referred for high clinical suspicion of obstructive sleep apnoea syndrome (OSA). Within 2 weeks, all the patients underwent both PSG performed by the same sleep technician, which were analysed by another blinded technician. Payments for each procedure were also calculated. Sixty-six patients (mean age: 49±13 years; mean body mass index: 30±7; mean Epworth Sleepiness Scale: 10±5) were included. The quality of recordings was poor in 1.5% of the attended PSG versus 4.7% for unattended PSG (P=0.36). Sleep efficiency at home was better (82% versus 75%, P<0.001), and sleep duration longer (412 min versus 365 min, P<0.001). Sleep latency was also shorter at home (28 min versus 45 min, P=0.004), and patients spent more time in rapid eye movement sleep (19% versus 16%, P=0.006). Apnoea-hypopnoea index (23 versus 26, P=0.08) was similar at home and in the sleep lab. Sixty-seven per cent of patients preferred home-based PSG. PSG payment was also lower at home (268 Euros versus 1057 Euros). We conclude that home-based PSG is associated with a better sleep efficiency. It also appears as feasible and reliable in patients with high preclinical suspicion for OSA. It is also more comfortable for the patients whose sleep efficiency is better and allows cost saving related to the absence of hospitalization.

  3. PET radiotracer [¹⁸F]-P6 selectively targeting COX-1 as a novel biomarker in ovarian cancer: preliminary investigation.

    PubMed

    Perrone, Maria Grazia; Malerba, Paola; Uddin, Md Jashim; Vitale, Paola; Panella, Andrea; Crews, Brenda C; Daniel, Cristina K; Ghebreselasie, Kebreab; Nickels, Mike; Tantawy, Mohammed N; Manning, H Charles; Marnett, Lawrence J; Scilimati, Antonio

    2014-06-10

    Cyclooxygenase-1 (COX-1), but not COX-2, is expressed at high levels in the early stages of human epithelial ovarian cancer where it seems to play a key role in cancer onset and progression. As a consequence, COX-1 is an ideal biomarker for early ovarian cancer detection. A series of novel fluorinated COX-1-targeted imaging agents derived from P6 was developed by using a highly selective COX-1 inhibitor as a lead compound. Among these new compounds, designed by structural modification of P6, 3-(5-chlorofuran-2-yl)-5-(fluoromethyl)-4-phenylisoxazole ([(18/19)F]-P6) is the most promising derivative [IC50 = 2.0 μM (purified oCOX-1) and 1.37 μM (hOVCAR-3 cell COX-1)]. Its tosylate precursor was also prepared and, a method for radio[(18)F]chemistry was developed and optimized. The radiochemistry was carried out using a carrier-free K(18)F/Kryptofix 2.2.2 complex, that afforded [(18)F]-P6 in good radiochemical yield (18%) and high purity (>95%). In vivo PET/CT imaging data showed that the radiotracer [(18)F]-P6 was selectively taken up by COX-1-expressing ovarian carcinoma (OVCAR 3) tumor xenografts as compared with the normal leg muscle. Our results suggest that [(18)F]-P6 might be an useful radiotracer in preclinical and clinical settings for in vivo PET-CT imaging of tissues that express elevated levels of COX-1.

  4. Theoretical Studies in Enhancing the Efficiency of Cathode and Anode Materials in PEMFC (Proton Exchange Membrane Fuel Cells)

    DTIC Science & Technology

    2011-03-04

    efficiency of cathode and anode materials in PEMFC (Proton Exchange Membrane Fuel Cells) 5a. CONTRACT NUMBER FA23861014012 5b. GRANT NUMBER 5c. PROGRAM...Rev. 8-98) Prescribed by ANSI Std Z39-18 Theoretical studies in enhancing the efficiency of cathode and anode materials in PEMFC (Proton Exchange

  5. Single Molecule Study on Incorporation Efficiency of DPO4 and Klenow Fragment to BPDE Adduct

    NASA Astrophysics Data System (ADS)

    Song, Lu; Yeh, Yin; Balhorn, Rod; Cosman, Monique

    2009-03-01

    DNA synthesis involving high fidelity A-family polymerases such as Klenow fragment is blocked by DNA adducts, while Y-family DNA polymerases such as Dpo4 can bypass the DNA adducts to resume DNA synthesis. So understanding the functional relationship between A-family and Y-family DNA polymerases in DNA replication and the mechanism of bypassing DNA adducts is of great help to explain the cause of mutagenesis. We introduce a flow cell on modified surface to study the incorporation efficiency of Dpo4 and Klenow fragments to benzo[a]pyrene-diol-epoxide (BPDE) adduct at single molecule level. Specifically, we anchor the labeled DNA onto the modified surface with adduct site open for nucleotide incorporation and flow the polymerases and labeled nucleotides into flow cell. With Total Internal Reflection Fluorescence Microscopy (TIRFM) we identify the incorporation of the nucleotides onto the anchored DNA template by identifying the co-localization of the template position and that of the labeled nucleotide. We further quantify the signal densities of the images obtained from the two different polymerases, thus examining whether incorporation reactions have been executed and quantifying the incorporation efficiency of the polymerases. We can also identify, on the specific adduct site, which nucleotide, if any, is incorporated by each of the two polymerases.

  6. [Study on the groundwater petroleum contaminant biodegradation by high efficient microorganism].

    PubMed

    Wang, Zhi-qiang; Wu, Qiang; Ye, Si-yuan; Li, Fu-qin; Xie, Hai-lan; Jin, Xiao-li

    2005-11-01

    The groundwater petroleum contaminant biodegradation effect by high efficient hybrid microorganism was. investigated and the groundwater contaminant biodegradation transportation mathematical model was established in this study. The high efficient bacteria was separated and filtrated from the soil contaminated by petroleum hydrocarbon, and it was identified as Pseudomonas, Flavobacterium and Micrococcus. The petroleum degradation rates by these three kinds microorganism were 62%, 56% and 62% respectively in 24 h, and the high petroleum biodegradation rate 85% could be achieved by the hybrid microorganism constituted by these three kinds of microorganism, which was higher than that of any other each single bacteria community. The hybrid microorganism in-flowed into the reactor imitating the aquifer media with the petroleum wastewater, and it could form a steady microorganism zone in the foreside of the reactor. The petroleum biodegradation rate could achieve 60% when the petroleum wastewater flowed through this microorganism zone and the average petroleum biodegradation rate could reach up to 90% in the effluent. The groundwater contaminant biodegradation transportation mathematical model can predict the biodegradation of the wastewater through the microorganism zone effectively, of which the calculating values have good relativity with those of measurement.

  7. Association analysis between feed efficiency studies and expression of hypothalamic neuropeptide genes in laying ducks.

    PubMed

    Zeng, T; Chen, L; Du, X; Lai, S J; Huang, S P; Liu, Y L; Lu, L Z

    2016-10-01

    Residual feed intake (RFI) is now considered a more reasonable metric to evaluate animal feed efficiency. In this study, the correlation between RFI and other feed efficiency traits was investigated and gene expression within the hypothalamus was determined in low RFI (LRFI) and high RFI (HRFI) ducks. Further, several hypothalamic neuropeptide genes were measured using quantitative real-time PCR. The mean feed intake value was 160 g/day, whereas the egg mass laid (EML) and body weight were approximately 62.4 g/day and 1.46 kg respectively. Estimates for heritability of RFI, feed conversion ratio (FCR) and feed intake were 0.26, 0.18 and 0.23 respectively. RFI is phenotypically positively correlated with feed intake and FCR (P < 0.01). The expression of neuropeptide Y (NPY) and neuropeptide Y receptor Y5 (NPY5R) mRNA was higher in HRFI ducks compared with LRFI ducks (P < 0.05), whereas that of proopiomelanocortin (POMC), melanocortin 4 receptor (MC4R) and cholecystokinin (CCK) was lower (P < 0.05). The mRNA expression of gonadotropin-releasing hormone 1 (luteinizing-releasing hormone) (GNRH1) and prolactin receptor (PRLR) was unchanged between LRFI and HRFI ducks. The results indicate that selection for LRFI could reduce feed intake without significant changes in EML, whereas selection on FCR will increase EML. © 2016 Stichting International Foundation for Animal Genetics.

  8. In Vitro Studies of Bacterial Cellulose and Magnetic Nanoparticles Smart Nanocomposites for Efficient Chronic Wounds Healing

    PubMed Central

    Bunea, Mihaela-Cristina; Stanescu, Paul; Casarica, Angela; Iovu, Horia; Zaharia, Catalin

    2015-01-01

    The quality of life of patients with chronic wounds can be extremely poor and, therefore, over the past decades, great efforts have been made to develop efficient strategies to improve the healing process and the social impact associated with these conditions. Cell based therapy, as a modern tissue engineering strategy, involves the design of 3D cell-scaffold bioconstructs obtained by preseeding drug loaded scaffolds with undifferentiated cells in order to achieve in situ functional de novo tissue. This paper reports on the development of bionanocomposites based on bacterial cellulose and magnetic nanoparticles (magnetite) for efficient chronic wounds healing. Composites were obtained directly in the cellulose bacterial culture medium by dispersing various amounts of magnetite nanoparticles during the biosynthesis process. After purification and drying, the membranes were characterized by Raman spectroscopy and X-ray diffraction to reveal the presence of magnetite within the bacterial cellulose matrix. Morphological investigation was employed through SEM and TEM analyses on bionanocomposites. The biocompatibility of these innovative materials was studied in relation to human adipose derived stem cells in terms of cellular morphology, viability, and proliferation as well as scaffolds cytotoxic potential. PMID:26106420

  9. An efficient hierarchical generalized linear mixed model for pathway analysis of genome-wide association studies.

    PubMed

    Wang, Lily; Jia, Peilin; Wolfinger, Russell D; Chen, Xi; Grayson, Britney L; Aune, Thomas M; Zhao, Zhongming

    2011-03-01

    In genome-wide association studies (GWAS) of complex diseases, genetic variants having real but weak associations often fail to be detected at the stringent genome-wide significance level. Pathway analysis, which tests disease association with combined association signals from a group of variants in the same pathway, has become increasingly popular. However, because of the complexities in genetic data and the large sample sizes in typical GWAS, pathway analysis remains to be challenging. We propose a new statistical model for pathway analysis of GWAS. This model includes a fixed effects component that models mean disease association for a group of genes, and a random effects component that models how each gene's association with disease varies about the gene group mean, thus belongs to the class of mixed effects models. The proposed model is computationally efficient and uses only summary statistics. In addition, it corrects for the presence of overlapping genes and linkage disequilibrium (LD). Via simulated and real GWAS data, we showed our model improved power over currently available pathway analysis methods while preserving type I error rate. Furthermore, using the WTCCC Type 1 Diabetes (T1D) dataset, we demonstrated mixed model analysis identified meaningful biological processes that agreed well with previous reports on T1D. Therefore, the proposed methodology provides an efficient statistical modeling framework for systems analysis of GWAS. The software code for mixed models analysis is freely available at http://biostat.mc.vanderbilt.edu/LilyWang.

  10. Growth rate analysis and efficient experimental design for tumor xenograft studies.

    PubMed

    Hather, Gregory; Liu, Ray; Bandi, Syamala; Mettetal, Jerome; Manfredi, Mark; Shyu, Wen-Chyi; Donelan, Jill; Chakravarty, Arijit

    2014-01-01

    Human tumor xenograft studies are the primary means to evaluate the biological activity of anticancer agents in late-stage preclinical drug discovery. The variability in the growth rate of human tumors established in mice and the small sample sizes make rigorous statistical analysis critical. The most commonly used summary of antitumor activity for these studies is the T/C ratio. However, alternative methods based on growth rate modeling can be used. Here, we describe a summary metric called the rate-based T/C, derived by fitting each animal's tumor growth to a simple exponential model. The rate-based T/C uses all of the data, in contrast with the traditional T/C, which only uses a single measurement. We compare the rate-based T/C with the traditional T/C and assess their performance through a bootstrap analysis of 219 tumor xenograft studies. We find that the rate-based T/C requires fewer animals to achieve the same power as the traditional T/C. We also compare 14-day studies with 21-day studies and find that 14-day studies are more cost efficient. Finally, we perform a power analysis to determine an appropriate sample size.

  11. A rapid and efficient method to study the function of crop plant transporters in Arabidopsis.

    PubMed

    Wang, Xiangfeng; Zhong, Fudi; Woo, Cheuk Hang; Miao, Yansong; Grusak, Michael A; Zhang, Xiaobo; Tu, Jumin; Wong, Yum Shing; Jiang, Liwen

    2017-03-01

    Iron (Fe) is an essential micronutrient for humans. Fe deficiency disease is widespread and has led to extensive studies on the mechanisms of Fe uptake and storage, especially in staple food crops such as rice. However, studies of functionally related genes in rice and other crops are often time and space demanding. Here, we demonstrate that transgenic Arabidopsis suspension culture cells and Arabidopsis plants can be used as an efficient expression system for gain-of-function study of selected transporters, using Fe transporters as a proof-of-principle. The vacuolar membrane transporters OsVIT1 and OsVIT2 have been described to be important for iron sequestration, and disruption of these two genes leads to Fe accumulation in rice seeds. In this study, we have taken advantage of the fluorescent-tagged protein GFP-OsVIT1, which functionally complements the Fe hypersensitivity of ccc1 yeast mutant, to generate transgenic Arabidopsis suspension cell lines and plants. GFP-OsVIT1 was shown to localize on the vacuolar membrane using confocal microscopy and immunogold EM. More importantly, the Fe concentration, as well as the concentration of Zn, in the transgenic cell lines and plants were significantly increased compared to that in the WT. Taken together, our study shows that the heterologous expression of rice vacuolar membrane transporter OsVIT1 in Arabidopsis system is functional and effectively enhances iron accumulation, indicating an useful approach for studying other putative transporters of crop plants in this system.

  12. Multivariate Meta-Analysis of Heterogeneous Studies Using Only Summary Statistics: Efficiency and Robustness

    PubMed Central

    Liu, Dungang; Liu, Regina; Xie, Minge

    2014-01-01

    Meta-analysis has been widely used to synthesize evidence from multiple studies for common hypotheses or parameters of interest. However, it has not yet been fully developed for incorporating heterogeneous studies, which arise often in applications due to different study designs, populations or outcomes. For heterogeneous studies, the parameter of interest may not be estimable for certain studies, and in such a case, these studies are typically excluded from conventional meta-analysis. The exclusion of part of the studies can lead to a non-negligible loss of information. This paper introduces a metaanalysis for heterogeneous studies by combining the confidence density functions derived from the summary statistics of individual studies, hence referred to as the CD approach. It includes all the studies in the analysis and makes use of all information, direct as well as indirect. Under a general likelihood inference framework, this new approach is shown to have several desirable properties, including: i) it is asymptotically as efficient as the maximum likelihood approach using individual participant data (IPD) from all studies; ii) unlike the IPD analysis, it suffices to use summary statistics to carry out the CD approach. Individual-level data are not required; and iii) it is robust against misspecification of the working covariance structure of the parameter estimates. Besides its own theoretical significance, the last property also substantially broadens the applicability of the CD approach. All the properties of the CD approach are further confirmed by data simulated from a randomized clinical trials setting as well as by real data on aircraft landing performance. Overall, one obtains an unifying approach for combining summary statistics, subsuming many of the existing meta-analysis methods as special cases. PMID:26190875

  13. Simple instrument for biochemical studies of the living human brain

    SciTech Connect

    Bice, A.N.; Wagner, H.N. Jr.; Lee, M.C.; Frost, J.J.

    1986-09-01

    A simple, relatively inexpensive radiation detection system was developed for measurement of positron-emitting receptor-binding drugs in the human brain. This high-efficiency coincidence counting system requires that only a few hundred microcuries of labeled drug be administered to the subject, thereby allowing for multiple studies without an excessive radiation dose. Measurement of the binding of (/sup 11/C)-carfentanil, a high-affinity synthetic opiate, to opiate receptors in the presence and in the absence of a competitive opiate antagonist exemplifies the use of this system for estimating different degrees of receptor binding of drugs in the human brain. The instrument has also been used for measurement of the transport into the brain of other positron-emitting radiotracers, such as large neutral amino acids.

  14. Systematical assessment of serum indices does not impair efficiency of clinical chemistry testing: a multicenter study.

    PubMed

    Lippi, Giuseppe; Avanzini, Paola; Campioli, Daniele; Da Rin, Giorgio; Dipalo, Mariella; Aloe, Rosalia; Giavarina, Davide; Salvagno, Gian Luca

    2013-09-01

    Despite manufacturers' claim that systematical assessment of serum indices does not impact on testing efficiency, there is widespread perception that this practice may increase the turnaround time (TAT). A multicenter investigation was planned to verify TAT and performance of serum indices on five different clinical chemistry analyzers. Twenty study samples prepared from p