WorldWideScience

Sample records for amorphous selenium digital

  1. The effect of amorphous selenium detector thickness on dual-energy digital breast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yue-Houng, E-mail: yuehoung.hu@gmail.com; Zhao, Wei [Department of Radiology, State University of New York at Stony Brook, L-4 120 Health Sciences Center, Stony Brook, New York 11794-8460 (United States)

    2014-11-01

    Purpose: Contrast enhanced (CE) imaging techniques for both planar digital mammography (DM) and three-dimensional (3D) digital breast tomosynthesis (DBT) applications requires x-ray photon energies higher than the k-edge of iodine (33.2 keV). As a result, x-ray tube potentials much higher (>40 kVp) than those typical for screening mammography must be utilized. Amorphous selenium (a-Se) based direct conversion flat-panel imagers (FPI) have been widely used in DM and DBT imaging systems. The a-Se layer is typically 200 μm thick with quantum detective efficiency (QDE) >87% for x-ray energies below 26 keV. However, QDE decreases substantially above this energy. To improve the object detectability of either CE-DM or CE-DBT, it may be advantageous to increase the thickness (d{sub Se}) of the a-Se layer. Increasing the d{sub Se} will improve the detective quantum efficiency (DQE) at the higher energies used in CE imaging. However, because most DBT systems are designed with partially isocentric geometries, where the gantry moves about a stationary detector, the oblique entry of x-rays will introduce additional blur to the system. The present investigation quantifies the effect of a-Se thickness on imaging performance for both CE-DM and CE-DBT, discussing the effects of improving photon absorption and blurring from oblique entry of x-rays. Methods: In this paper, a cascaded linear system model (CLSM) was used to investigate the effect of d{sub Se} on the imaging performance (i.e., MTF, NPS, and DQE) of FPI in CE-DM and CE-DBT. The results from the model are used to calculate the ideal observer signal-to-noise ratio, d′, which is used as a figure-of-merit to determine the total effect of increasing d{sub Se} for CE-DM and CE-DBT. Results: The results of the CLSM show that increasing d{sub Se} causes a substantial increase in QDE at the high energies used in CE-DM. However, at the oblique projection angles used in DBT, the increased length of penetration through a

  2. Fracture Phenomena in Amorphous Selenium

    DEFF Research Database (Denmark)

    Lindegaard-Andersen, Asger; Dahle, Birgit

    1966-01-01

    Fracture surfaces of amorphous selenium broken in flexure at room temperature have been studied. The fracture velocity was found to vary in different regions of the fracture surface. Peculiar features were observed in a transition zone between fast and slower fracture. In this zone cleavage steps...

  3. New development of large-area direct conversion detector for digital radiography using amorphous selenium with a C60-doped polymer layer

    Science.gov (United States)

    Nariyuki, F.; Imai, S.; Watano, H.; Nabeta, T.; Hosoi, Y.

    2010-04-01

    We have developed a novel direct conversion detector for digital radiography by using a fullerene (C60)-doped polymer layer added on a thick amorphous selenium (a-Se) layer coupled to an amorphous silicon thin-film transistor (a-Si TFT) array. This detector exhibits considerable improvement in the lag characteristics and durability in high ambient temperatures. The C60-doped polymer layer, which is directly and uniformly solution cast on the a-Se layer and followed by an inorganic electron-transporting layer, smoothly changes the electronic junction between the a-Se layer and the inorganic layer. It lubricates the emission of photocurrents from the a-Se photo-conversion layer and leads to the improved lag characteristics. Another merit of using a C60-doped polymer is that it is stabile in high-temperature ambient conditions and is not degraded by humidity or a large amount of X-ray exposure. The polymer layer prevents the crystallization of a-Se, which otherwise occurs on exposure of a-Se to high temperature not only during the deposition of the inorganic layer or the metal electrode layer in the manufacturing process but also in actual use. A prototype detector, with a size of 17 in × 17 in and a pixel pitch of 150 μm, exhibited a good resolution; its DQE is approximately 48% at 1 cy/mm in 258 μC/kg (RQA5). This new development can simplify cooling apparatus and detector modules and also make a wide range of operational environments available. In addition, the improved lag characteristics make it possible to reduce the exposure intervals for static imaging, tomosynthesis, and other various exposure techniques.

  4. Structure of amorphous selenium studied by neutron diffraction

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Knudsen, Torben Steen; Carneiro, K.

    1975-01-01

    treatment, the neutron scattering cross sections of selenium are determined to be sigmacoh = 8.4±0.1 b and sigmainc = 0.1±0.1 b. Using the fact that S (kappa) for large kappa's is determined by the short distances in the sample, a new method for extrapolation of the experimental S (kappa) until convergence......Neutron diffraction measurements on amorphous selenium have been performed at 293 and 80 K. Careful analyses of the instrumental corrections were made to avoid systematic errors in the measured structure factor S (kappa) in the wave vector region 0 ? kappa ? 12 Å−1. As a result of the data...... is proposed. This allows an accurate determination of g (r) showing peaks at distances that agree well with the previous x−ray experiment by Kaplow et al. for distances up to 11 Å. However, only partial agreement is obtained when finer details of g (r), e.g., the width of the first peak, are considered...

  5. Amorphous selenium based detectors for medical imaging applications

    Science.gov (United States)

    Mandal, Krishna C.; Kang, Sung H.; Choi, Michael; Jellison, Gerald E., Jr.

    2006-08-01

    We have developed and characterized large volume amorphous (a-) selenium (Se) stabilized alloys for room temperature medical imaging devices and high-energy physics detectors. The synthesis and preparation of well-defined and high quality a-Se (B, As, Cl) alloy materials have been conducted using a specially designed alloying reactor at EIC and installed in an argon atmosphere glove box. The alloy composition has been precisely controlled and optimized to ensure good device performance. The synthesis of large volume boron (B) doped (natural and isotopic 10B) a-Se (As, Cl) alloys has been carried out by thoroughly mixing vacuum distilled and zone-refined (ZR) Se with previously synthesized Se-As master alloys, Se-Cl master alloys and B. The synthesized a-Se (B, As, Cl) alloys have been characterized by x-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infra-red spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectroscopy (ICP-MS), and detector testing. The a- Se alloys have shown high promise for x-ray detectors with its high dark resistivity (10 10-10 13 Ωcm), good charge transport properties, and cost-effective large area scalability. Details of various steps about detector fabrication and testing of these imaging devices are also presented.

  6. Investigation of hole-blocking contacts for high-conversion-gain amorphous selenium detectors for X-ray imaging

    NARCIS (Netherlands)

    Abbaszadeh, S.; Allec, N.; Ghanbarzadeh, S.; Shafique, U.; Karim, K.S.

    2012-01-01

    In this paper, we investigated different organic and inorganic hole-blocking contacts for amorphous selenium (a-Se)-based photodetectors: CeO2, TiO2, perylene tetracarboxylic bisbenzimidazole (PTCBI), and polyimide (PI). CeO2 has previously been used as a blocking layer for high-gain a-Se devices.

  7. Selenium

    Science.gov (United States)

    Stillings, Lisa L.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Selenium (Se) was discovered in 1817 in pyrite from copper mines in Sweden. It is a trace element in Earth’s crust, with an abundance of three to seven orders of magnitude less than the major rock-forming elements. Commercial use of selenium began in the United States in 1910, when it was used as a pigment for paints, ceramic glazes, and red glass. Since that time, it has had many other economic uses—notably, in the 1930s and 1940s, when it was used in rectifiers (which change alternating current to direct current), and in the 1960s, when it began to be used in the liner of photocopier drums. In the 21st century, other compounds have replaced selenium in these older products; modern uses for selenium include energy-efficient windows that limit heat transfer and thin-film photovoltaic cells that convert solar energy into electricity.In Earth’s crust, selenium is found as selenide minerals, selenate and selenite salts, and as substitution for sulfur in sulfide minerals. It is the sulfide minerals, most commonly those in porphyry copper deposits, that provide the bulk of the selenium produced for the international commodity market. Selenium is obtained as a byproduct of copper refining and recovered from the anode slimes generated in electrolytic production of copper. Because of this, the countries that have the largest resources and (or) reserves of copper also have the largest resources and (or) reserves of selenium.Because selenium occurs naturally in Earth’s crust, its presence in air, water, and soil results from both geologic reactions and human activity. Selenium is found concentrated naturally in soils that overlie bedrock with high selenium concentrations. Selenium mining, processing, use in industrial and agricultural applications, and disposal may all contribute selenium to the environment. A well-known case of selenium contamination from agricultural practices was discovered in 1983 in the Kesterson National Wildlife Refuge in California. There

  8. X-ray imaging with amorphous selenium: Pulse height measurements of avalanche gain fluctuations

    International Nuclear Information System (INIS)

    Lui, Brian J. M.; Hunt, D. C.; Reznik, A.; Tanioka, K.; Rowlands, J. A.

    2006-01-01

    Avalanche multiplication in amorphous selenium (a-Se) can provide a large, adjustable gain for active matrix flat panel imagers (AMFPI), enabling quantum noise limited x-ray imaging during both radiography and fluoroscopy. In the case of direct conversion AMFPI, the multiplication factor for each x ray is a function of its depth of interaction, and the resulting variations in gain can reduce the detective quantum efficiency (DQE) of the system. An experimental method was developed to measure gain fluctuations by analyzing images of individual x rays that were obtained using a video camera with an a-Se target operated in avalanche mode. Pulse height spectra (PHS) of the charge produced per x ray were recorded for monoenergetic 30.9, 49.4, and 73.8 keV x-ray sources. The rapid initial decay and long tail of each PHS can be explained by a model in which positive charge dominates the initiation of avalanche. The Swank information factor quantifies the effect of gain fluctuation on DQE and was calculated from the PHS. The information factor was found to be 0.5 for a 25 μm a-Se layer with a maximum gain of ∼300. Changing the energy of the incident x ray influenced the range of the primary photoelectron and noticeably affected the tail of the experimental PHS, but did not significantly change the avalanche Swank factor

  9. An amorphous selenium based positron emission mammography camera with avalanche gain.

    Science.gov (United States)

    Reznik, A; Lui, B J M; Rowlands, J A

    2005-02-01

    Early diagnosis of breast cancer is crucial for effective treatment, and the need exists for greater detection ability and specificity than possible by screening x-ray mammography (currently the primary imaging technique for the detection of breast lesions). Positron Emission Tomography (PET) using the radiotracer 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) offers a noninvasive, highly sensitive method for the diagnosis of breast cancer. Images from PET contain unique metabolic information that is not available from anatomical imaging techniques. We propose a Positron Emission Mammography (PEM) imaging system that maintains the established high specificity of FDG PET while providing improved collection efficiency for the radiotracer signal and the potential for images with better spatial resolution. This PEM system will enable detection of lesions that are considerably smaller than those that can be visualized using whole body PET imaging. The compact dual-head PEM camera will be based on an amorphous selenium (a-Se) avalanche photodetector and the scintillator lutetium oxyorthosilicate (LSO). The camera promises high collection efficiency by combining the fast scintillation light decay and high light yield of LSO with the excellent quantum efficiency, large avalanche gain, and rapid response time of a-Se. We have measured the gain and readout time of an 8 microm a-Se layer and demonstrated the feasibility of the proposed PEM camera.

  10. Selenium

    Science.gov (United States)

    ... of or treat cognitive decline in elderly people. Thyroid disease The thyroid gland has high amounts of selenium ... can help treat or reduce the risk of thyroid disease is not clear. More research is needed to ...

  11. MO-AB-BRA-07: Low Dose Imaging with Avalanche Amorphous Selenium Flat Panel Imager

    Energy Technology Data Exchange (ETDEWEB)

    Scheuermann, J; Howansky, A; Goldan, A; Tanioka, K; Zhao, W [Stony Brook University, Stony Brook, New York (United States); Leveille, S; Tousignant, O [2Analogic Canada, Saint-laurent, Quebec (Canada)

    2016-06-15

    Purpose: We present the first active matrix flat panel imager (AMFPI) capable of producing x-ray quantum noise limited images at low doses by overcoming the electronic noise through signal amplification by photoconductive avalanche gain (gav). The indirect detector fabricated uses an optical sensing layer of amorphous selenium (a-Se) known as High-Gain Avalanche Rushing Photoconductor (HARP). The detector design is called Scintillator HARP (SHARP)-AMFPI. This is the first image sensor to utilize solid-state HARP technology. Methods: The detector’s electronic readout is a 24 × 30 cm{sup 2} array of thin film transistors (TFT) with a pixel pitch of 85 µm. The HARP structure consists of a 15 µm layer of a-Se isolated from the high voltage (HV) and signal electrode by a 2 µm thick hole blocking layer and electron blocking layer, respectively, to reduce dark current. A 150 µm thick structured CsI scintillator with reflective backing and a fiber optic faceplate (FOP) was coupled to the semi-transparent HV bias electrode of the HARP structure. Images were acquired using a 30 kVp Mo/Mo spectrum typically used in mammography. Results: Optical sensitivity measurements demonstrate that gav = 76 ± 5 can be achieved over the entire active area of the detector. At a constant dose to the detector of 6.67 µGy, image quality increases with gav until the effective electronic noise is negligible. Quantum noise limited images can be obtained with doses as low as 0.18 µGy. Conclusion: We demonstrate the feasibility of utilizing avalanche gain to overcome electronic noise. The indirect detector fabricated is the first solid-state imaging sensor to use HARP, and the largest active area HARP sensor to date. Our future work is to improve charge transport within the HARP structure and utilize a transparent HV electrode.

  12. Digital radiography of the thorax - the selenium detector compared with other imaging systems

    International Nuclear Information System (INIS)

    Schaefer-Prokop, C.; Prokop, M.

    1996-01-01

    Phantom studies were compared with clinical studies for a comparative analysis of the diagnostic performance of conventional and digital imaging systems. The selenium detector is found to be superior in a number of tasks, and on the whole is judged to adequately perform the multiple tasks of thorax radiography.(Orig.) [de

  13. Measured and calculated K-fluorescence effects on the MTF of an amorphous-selenium based CCD x-ray detector.

    Science.gov (United States)

    Hunter, David M; Belev, George; Kasap, Safa; Yaffe, Martin J

    2012-02-01

    Theoretical reasoning suggests that direct conversion digital x-ray detectors based upon photoconductive amorphous-selenium (a-Se) could attain very high values of the MTF (modulation transfer function) at spatial frequencies well beyond 20 cycles mm(-1). One of the fundamental factors affecting resolution loss, particularly at x-ray energies just above the K-edge of selenium (12.66 keV), is the K-fluorescence reabsorption mechanism, wherein energy can be deposited in the detector at locations laterally displaced from the initial x-ray interaction site. This paper compares measured MTF changes above and below the Se K-edge of a CCD based a-Se x-ray detector with theoretical expectations. A prototype 25 μm sampling pitch (Nyquist frequency = 20 cycles mm(-1), 200 μm thick a-Se layer based x-ray detector, utilizing a specialized CCD readout device (200 × 400 area array), was used to make edge images with monochromatic x-rays above and below the K-edge of Se. A vacuum double crystal monochromator, exposed to polychromatic x-rays from a synchrotron, formed the monochromatic x-ray source. The monochromaticity of the x-rays was 99% or better. The presampling MTF was determined using the slanted edge method. The theory modeling the MTF performance of the detector includes the basic x-ray interaction physics in the a-Se layer as well as effects related to the operation of the CCD and charge trapping at a blocking layer present at the CCD/a-Se interface. The MTF performance of the prototype a-Se CCD was reduced from the theoretical value prescribed by the basic Se x-ray interaction physics, principally by the presence of a blocking layer. Nevertheless, the K-fluorescence reduction in the MTF was observed, approximately as predicted by theory. For the CCD prototype detector, at five cycles mm(-1), there was a 14% reduction of the MTF, from a value of 0.7 below the K-edge of Se, to 0.6 just above the K-edge. The MTF of an a-Se x-ray detector has been measured using

  14. Radiation exposure in full-field digital mammography with a selenium flat-panel detector; Strahlenexposition bei der digitalen Vollfeldmammographie mit einem Selen-Flachdetektor

    Energy Technology Data Exchange (ETDEWEB)

    Gosch, D.; Jendrass, S.; Scholz, M.; Kahn, T. [Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie, Universitaetsklinikum Leipzig AoeR (Germany)

    2006-07-15

    Purpose: calculation of the average glandular dose for mammography on a full-field digital mammography system using a selenium flat-panel detector. Materials and methods: mammographic examinations were carried out using the selenia digital mammographic system from Lorad/Hologic. 1992 mammographies of 500 patients in cranio-caudal and medio-lateral projections were evaluated. Based on the recorded exposure conditions (tube voltage, tube loading, filtration, compressed breast thickness), the entrance surface air kerma was calculated by multiplying the tube loading by the measured tube output and was corrected according to the inverse square law. The average glandular dose was determined for each exposure by multiplying the entrance surface air kerma value by the relevant conversion factor for a breast composition of 50% adipose tissue and 50% glandular tissue by weight. Results: the mean values for patient age and compressed breast thickness were 61 years and 58 mm, respectively. The average glandular dose was 1.57 mGy for a single view (1.46 mGy for cranio-caudal view images and 1.68 mGy for medio-lateral view images). Conclusion: full-field digital mammography with a selenium flat-panel detector requires a dose similar to that of units with a flat-panel detector based on amorphous silicon and a dose approximately 20% lower than that of conventional screen/film mammography. (orig.)

  15. TU-F-18C-02: Increasing Amorphous Selenium Thickness in Direct Conversion Flat-Panel Imagers for Contrast-Enhanced Dual-Energy Breast Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Scaduto, DA; Hu, Y-H; Zhao, W [Stony Brook University, Stony Brook, NY (United States)

    2014-06-15

    Purpose: Contrast-enhanced (CE) breast imaging using iodinated contrast agents requires imaging with x-ray spectra at energies greater than those used in mammography. Optimizing amorphous selenium (a-Se) flat panel imagers (FPI) for this higher energy range may increase lesion conspicuity. Methods: We compare imaging performance of a conventional FPI with 200 μm a-Se conversion layer to a prototype FPI with 300 μm a-Se layer. Both detectors are evaluated in a Siemens MAMMOMAT Inspiration prototype digital breast tomosynthesis (DBT) system using low-energy (W/Rh 28 kVp) and high-energy (W/Cu 49 kVp) x-ray spectra. Detectability of iodinated lesions in dual-energy images is evaluated using an iodine contrast phantom. Effects of beam obliquity are investigated in projection and reconstructed images using different reconstruction methods. The ideal observer signal-to-noise ratio is used as a figure-of-merit to predict the optimal a-Se thickness for CE lesion detectability without compromising conventional full-field digital mammography (FFDM) and DBT performance. Results: Increasing a-Se thickness from 200 μm to 300 μm preserves imaging performance at typical mammographic energies (e.g. W/Rh 28 kVp), and improves the detective quantum efficiency (DQE) for high energy (W/Cu 49 kVp) by 30%. While the more penetrating high-energy x-ray photons increase geometric blur due to beam obliquity in the FPI with thicker a-Se layer, the effect on lesion detectability in FBP reconstructions is negligible due to the reconstruction filters employed. Ideal observer SNR for CE objects shows improvements in in-plane detectability with increasing a-Se thicknesses, though small lesion detectability begins to degrade in oblique projections for a-Se thickness above 500 μm. Conclusion: Increasing a-Se thickness in direct conversion FPI from 200 μm to 300 μm improves lesion detectability in CE breast imaging with virtually no cost to conventional FFDM and DBT. This work was partially

  16. Suspicious amorphous microcalcifications detected on full-field digital mammography: correlation with histopathology

    Directory of Open Access Journals (Sweden)

    Vera Christina Camargo de Siqueira Ferreira

    2018-03-01

    Full Text Available Abstract Objective: To evaluate suspicious amorphous calcifications diagnosed on full-field digital mammography (FFDM and establish correlations with histopathology findings. Materials and Methods: This was a retrospective study of 78 suspicious amorphous calcifications (all classified as BI-RADS® 4 detected on FFDM. Vacuum-assisted breast biopsy (VABB was performed. The histopathological classification of VABB core samples was as follows: pB2 (benign; pB3 (uncertain malignant potential; pB4 (suspicion of malignancy; and pB5 (malignant. Treatment was recommended for pB5 lesions. To rule out malignancy, surgical excision was recommended for pB3 and pB4 lesions. Patients not submitted to surgery were followed for at least 6 months. Results: Among the 78 amorphous calcifications evaluated, the histopathological analysis indicated that 8 (10.3% were malignant/suspicious (6 classified as pB5 and 2 classified as pB4 and 36 (46.2% were benign (classified as pB2. The remaining 34 lesions (43.6% were classified as pB3: 33.3% were precursor lesions (atypical ductal hyperplasia, lobular neoplasia, or flat epithelial atypia and 10.3% were high-risk lesions. For the pB3 lesions, the underestimation rate was zero. Conclusion: The diagnosis of precursor lesions (excluding atypical ductal hyperplasia, which can be pB4 depending on the severity and extent of the lesion should not necessarily be considered indicative of underestimation of malignancy. Suspicious amorphous calcifications correlated more often with precursor lesions than with malignant lesions, at a ratio of 3:1.

  17. Enriched Boron-Doped Amorphous Selenium Based Position-Sensitive Solid-State Thermal Neutron Detector for MPACT Applications

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Krishna [Univ. of South Carolina, Columbia, SC (United States)

    2017-09-29

    High-efficiency thermal neutron detectors with compact size, low power-rating and high spatial, temporal and energy resolution are essential to execute non-proliferation and safeguard protocols. The demands of such detector are not fully covered by the current detection system such as gas proportional counters or scintillator-photomultiplier tube combinations, which are limited by their detection efficiency, stability of response, speed of operation, and physical size. Furthermore, world-wide shortage of 3He gas, required for widely used gas detection method, has further prompted to design an alternative system. Therefore, a solid-state neutron detection system without the requirement of 3He will be very desirable. To address the above technology gap, we had proposed to develop new room temperature solidstate thermal neutron detectors based on enriched boron (10B) and enriched lithium (6Li) doped amorphous Se (As- 0.52%, Cl 5 ppm) semiconductor for MPACT applications. The proposed alloy materials have been identified for its many favorable characteristics - a wide bandgap (~2.2 eV at 300 K) for room temperature operation, high glass transition temperature (tg ~ 85°C), a high thermal neutron cross-section (for boron ~ 3840 barns, for lithium ~ 940 barns, 1 barn = 10-24 cm2), low effective atomic number of Se for small gamma ray sensitivity, and high radiation tolerance due to its amorphous structure.

  18. Digital image processing of nanometer-size metal particles on amorphous substrates

    Science.gov (United States)

    Soria, F.; Artal, P.; Bescos, J.; Heinemann, K.

    1989-01-01

    The task of differentiating very small metal aggregates supported on amorphous films from the phase contrast image features inherently stemming from the support is extremely difficult in the nanometer particle size range. Digital image processing was employed to overcome some of the ambiguities in evaluating such micrographs. It was demonstrated that such processing allowed positive particle detection and a limited degree of statistical size analysis even for micrographs where by bare eye examination the distribution between particles and erroneous substrate features would seem highly ambiguous. The smallest size class detected for Pd/C samples peaks at 0.8 nm. This size class was found in various samples prepared under different evaporation conditions and it is concluded that these particles consist of 'a magic number' of 13 atoms and have cubooctahedral or icosahedral crystal structure.

  19. "This Ever More Amorphous Thing called Digital Humanities": Whither the Humanities Project?

    Science.gov (United States)

    Deegan, Marilyn

    2014-01-01

    In 2012, Digital Humanities became one of the most talked-about topics in the humanities and was suggested as a movement that could possibly help halt the decline in the traditional humanities. A flurry of books appeared, and "AHHE" produced two special issues, "Digital humanities," "digital futures" and "The…

  20. Entrapped elemental selenium nanoparticles affect physicochemical properties of selenium fed activated sludge.

    Science.gov (United States)

    Jain, Rohan; Seder-Colomina, Marina; Jordan, Norbert; Dessi, Paolo; Cosmidis, Julie; van Hullebusch, Eric D; Weiss, Stephan; Farges, François; Lens, Piet N L

    2015-09-15

    Selenite containing wastewaters can be treated in activated sludge systems, where the total selenium is removed from the wastewater by the formation of elemental selenium nanoparticles, which are trapped in the biomass. No studies have been carried out so far on the characterization of selenium fed activated sludge flocs, which is important for the development of this novel selenium removal process. This study showed that more than 94% of the trapped selenium in activated sludge flocs is in the form of elemental selenium, both as amorphous/monoclinic selenium nanospheres and trigonal selenium nanorods. The entrapment of the elemental selenium nanoparticles in the selenium fed activated sludge flocs leads to faster settling rates, higher hydrophilicity and poorer dewaterability compared to the control activated sludge (i.e., not fed with selenite). The selenium fed activated sludge showed a less negative surface charge density as compared to the control activated sludge. The presence of trapped elemental selenium nanoparticles further affected the spatial distribution of Al and Mg in the activated sludge flocs. This study demonstrated that the formation and subsequent trapping of elemental selenium nanoparticles in the activated sludge flocs affects their physicochemical properties. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Selenium semiconductor core optical fibers

    Directory of Open Access Journals (Sweden)

    G. W. Tang

    2015-02-01

    Full Text Available Phosphate glass-clad optical fibers containing selenium (Se semiconductor core were fabricated using a molten core method. The cores were found to be amorphous as evidenced by X-ray diffraction and corroborated by Micro-Raman spectrum. Elemental analysis across the core/clad interface suggests that there is some diffusion of about 3 wt % oxygen in the core region. Phosphate glass-clad crystalline selenium core optical fibers were obtained by a postdrawing annealing process. A two-cm-long crystalline selenium semiconductor core optical fibers, electrically contacted to external circuitry through the fiber end facets, exhibit a three times change in conductivity between dark and illuminated states. Such crystalline selenium semiconductor core optical fibers have promising utility in optical switch and photoconductivity of optical fiber array.

  2. Selenium essentials

    CERN Document Server

    Sams, Prashanth

    2015-01-01

    If you are a developer who wants to migrate from Selenium RC or any other automation tool to Selenium WebDriver, then this book is for you. Knowledge of automation tools is necessary to follow the examples in this book.

  3. Amorphous Zinc Oxide Integrated Wavy Channel Thin Film Transistor Based High Performance Digital Circuits

    KAUST Repository

    Hanna, Amir

    2015-12-04

    High performance thin film transistor (TFT) can be a great driving force for display, sensor/actuator, integrated electronics, and distributed computation for Internet of Everything applications. While semiconducting oxides like zinc oxide (ZnO) present promising opportunity in that regard, still wide area of improvement exists to increase the performance further. Here, we show a wavy channel (WC) architecture for ZnO integrated TFT which increases transistor width without chip area penalty, enabling high performance in material agnostic way. We further demonstrate digital logic NAND circuit using the WC architecture and compare it to the conventional planar architecture. The WC architecture circuits have shown 2× higher peak-to-peak output voltage for the same input voltage. They also have 3× lower high-to-low propagation delay times, respectively, when compared to the planar architecture. The performance enhancement is attributed to both extra device width and enhanced field effect mobility due to higher gate field electrostatics control.

  4. Electrical characteristics of hybrid detector based Gd2O2S:Tb-Selenium for digital radiation imaging

    International Nuclear Information System (INIS)

    Kang, Sang-Sik; Park, Ji-Koon; Choi, Jang-Yong; Cha, Byung-Yul; Cho, Sung-Ho; Nam, Sang-Hee

    2005-01-01

    Fine Gd 2 O 2 S:Tb powders were synthesized by using a solution-combustion method for a high-resolution digital X-ray imaging detector. The PL spectrum showed that the phosphor was fully crystallized and that the Tb 3+ ions substituted well for the Gd 3+ sites. To investigate the X-ray response of the phosphor, a uniform Gd 2 O 2 S:Tb film was grown using a screen-printing method. The X-ray sensitivities of the 100 μm-Gd 2 O 2 S:Tb/30 μm -Se and 200 μm -Se detector were 470 and 420 pC/cm 2 /mR, respectively, at an electric field of 10 V/μm. The results of the study suggest that the hybrid detector has a significant potential in the application of digital radiography and fluoroscopy systems

  5. Amorphous magnetism

    International Nuclear Information System (INIS)

    Rechenberg, H.R.

    1984-01-01

    The consequences of disorder on magnetic properties of solids are examined. In this context the word 'disorder' is not synonimous of structural amorphicity; chemical disorder can be achieved e.g. by randomly diffusing magnetic atoms on a nonmagnetic crystalline lattice. The name Amorphous Magnetism must be taken in a broad sense. (Author) [pt

  6. Aquatic Life Criterion - Selenium

    Science.gov (United States)

    Documents pertaining to the 2016 Acute and Chronic Ambient Aquatic Life Water Quality Criteria for Selenium (Freshwater). These documents include what the safe levels of Selenium are in water for the majority of species.

  7. Selenium and Human Health

    Directory of Open Access Journals (Sweden)

    M Abedi

    2013-04-01

    Full Text Available Introduction: Selenium is an essential element for human health and it is toxic at high concentrations. Selenium is a constituent component of selenoproteins that have enzymatic and structural roles in human biochemistry. Selenium is a best antioxidant and catalyst for production of thyroid hormone. This element has the key role in the immune function; prevention of AIDS progression and the deactivity of toxins. Furthermore, selenium is essential for sperm motility and can reduce abortions. Selenium deficiency was also associated with adverse mood states. The findings regarding cardiovascular disease risk related to selenium deficiency is unclear, though other conditions such as vascular inflammation, oxidative stress and selenium deficiency can cause this disease too. Moreover, consuming of 60 mg of selenium per day may be associated with reduction of cancer risk. In this study, a review of studies has been performed on the biochemical function of selenium toxicity, and its effects on human health. Furthermore, certain identified cancers associated with selenium have been discussed to absorb more attention to the status of this element and also as a guide for further studies. Selenium plays the dual character (useful and harmful in human health, and then it is necessary to determine the concentration of this element in body fluids and tissues. An appropriate method for routine measurement of selenium in clinical laboratories is electro thermal atomic absorption spectrometry (ETAAS with very low detection limit and good precision.

  8. Amorphous nanophotonics

    CERN Document Server

    Scharf, Toralf

    2013-01-01

    This book represents the first comprehensive overview over amorphous nano-optical and nano-photonic systems. Nanophotonics is a burgeoning branch of optics that enables many applications by steering the mould of light on length scales smaller than the wavelength with devoted nanostructures. Amorphous nanophotonics exploits self-organization mechanisms based on bottom-up approaches to fabricate nanooptical systems. The resulting structures presented in the book are characterized by a deterministic unit cell with tailored geometries; but their spatial arrangement is not controlled. Instead of periodic, the structures appear either amorphous or random. The aim of this book is to discuss all aspects related to observable effects in amorphous nanophotonic material and aspects related to their design, fabrication, characterization and integration into applications. The book has an interdisciplinary nature with contributions from scientists in physics, chemistry and materials sciences and sheds light on the topic fr...

  9. Amorphous In–Ga–Zn–O thin-film transistor active pixel sensor x-ray imager for digital breast tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chumin; Kanicki, Jerzy, E-mail: kanicki@eecs.umich.edu [Solid-State Electronic Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-09-15

    Purpose: The breast cancer detection rate for digital breast tomosynthesis (DBT) is limited by the x-ray image quality. The limiting Nyquist frequency for current DBT systems is around 5 lp/mm, while the fine image details contained in the high spatial frequency region (>5 lp/mm) are lost. Also today the tomosynthesis patient dose is high (0.67–3.52 mGy). To address current issues, in this paper, for the first time, a high-resolution low-dose organic photodetector/amorphous In–Ga–Zn–O thin-film transistor (a-IGZO TFT) active pixel sensor (APS) x-ray imager is proposed for next generation DBT systems. Methods: The indirect x-ray detector is based on a combination of a novel low-cost organic photodiode (OPD) and a cesium iodide-based (CsI:Tl) scintillator. The proposed APS x-ray imager overcomes the difficulty of weak signal detection, when small pixel size and low exposure conditions are used, by an on-pixel signal amplification with a significant charge gain. The electrical performance of a-IGZO TFT APS pixel circuit is investigated by SPICE simulation using modified Rensselaer Polytechnic Institute amorphous silicon (a-Si:H) TFT model. Finally, the noise, detective quantum efficiency (DQE), and resolvability of the complete system are modeled using the cascaded system formalism. Results: The result demonstrates that a large charge gain of 31–122 is achieved for the proposed high-mobility (5–20 cm{sup 2}/V s) amorphous metal-oxide TFT APS. The charge gain is sufficient to eliminate the TFT thermal noise, flicker noise as well as the external readout circuit noise. Moreover, the low TFT (<10{sup −13} A) and OPD (<10{sup −8} A/cm{sup 2}) leakage currents can further reduce the APS noise. Cascaded system analysis shows that the proposed APS imager with a 75 μm pixel pitch can effectively resolve the Nyquist frequency of 6.67 lp/mm, which can be further improved to ∼10 lp/mm if the pixel pitch is reduced to 50 μm. Moreover, the

  10. Muonic X-ray intensities in phosphorus- and selenium modifications

    International Nuclear Information System (INIS)

    Kaeser, K.; Robert-Tissot, B.; Schaller, L.A.; Schellenberg, L.; Schneuwly, H.

    1979-01-01

    Muonic X-ray intensity measurements have been performed at SIN on allotropic modifications of phosphorus (white, red and black) and of selenium (red and black). Structure effects have been found in the intensity ratios of the K-series between amorphous and crystalline modifications of the same element. The effect in the higher series (Se) is less pronounced. On the other hand, the two crystalline phosphorus modifications (red and black) show the same intensity behavior. The root-mean-square radii 2 >sup(1/2) of phosphorus and (natural) selenium were found to be 3.187(3) fm and 4.138(1) fm respectively. (Auth.)

  11. Digital radiography of the skeleton using a large-area detector based on amorphous silicon technology: Image quality and potential for dose reduction in comparison with screen-film radiography

    International Nuclear Information System (INIS)

    Volk, M.; Strotzer, M.; Holzkneckt, N.; Manke, C.; Lenhart, M.; Gmeinwieser, J.; Link, J.; Reiser, M.; Feuerback, S.

    2000-01-01

    AIM: The purpose of this study was to evaluate a large-area, flat-panel X-ray detector (FD), based on caesium-iodide (CsI) and amorphous silicon (a-Si) with respect to skeletal radiography. Conventional images were compared with digital radiographs using identical and reduced radiation doses. MATERIALS AND METHODS: Thirty consecutive patients were studied prospectively using conventional screen-film radiography (SFR; detector dose 2.5 μGy). Digital images were taken from the same patients with detector doses of 2.5, 1.25 and 0.625 μGy, respectively. The active-matrix detector had a panel size of 43 x 43 cm, a matrix of 3 x 3K, and a pixel size of 143 μm. All hard copies were presented in a random order to eight independent observers, who rated image quality according to subjective quality criteria. Results were assessed for significance using the Student's t -test (confidence level 95%). RESULTS: A statistically significant preference for digital over conventional images was revealed for all quality criteria, except for over-exposure (detector dose 2.5 μGy). Digital images with a 50% dose showed a small, statistically not significant, inferiority compared with SFR. The FD-technique was significantly inferior to SFR at 75% dose reduction regarding bone cortex and trabecula, contrast and overall impression. No statistically significant differences were found with regard to over- and under-exposure and soft tissue presentation. CONCLUSION: Amorphous silicon-based digital radiography yields good image quality. The potential for dose reduction depends on the clinical query. Volk, M. (2000)

  12. Digital X-ray Imaging in Dentistry

    International Nuclear Information System (INIS)

    Kim, Eun Kyung

    1999-01-01

    In dentistry, Radio Visio Graphy was introduced as a first electronic dental x-ray imaging modality in 1989. Thereafter, many types of direct digital radiographic systems have been produced in the last decade. They are based either on charge-coupled device (CCD) or on storage phosphor technology. In addition, new types of digital radiographic system using amorphous selenium, image intensifier etc. are under development. Advantages of digital radiographic system are elimination of chemical processing, reduction in radiation dose, image processing, computer storage, electronic transfer of images and so on. Image processing includes image enhancement, image reconstruction, digital subtraction, etc. Especially digital subtraction and reconstruction can be applied in many aspects of clinical practice and research. Electronic transfer of images enables filmless dental hospital and teleradiology/teledentistry system. Since the first image management and communications system (IMACS) for dentomaxillofacial radiology was reported in 1992, IMACS in dental hospital has been increasing. Meanwhile, researches about computer-assisted diagnosis, such as structural analysis of bone trabecular patterns of mandible, feature extraction, automated identification of normal landmarks on cephalometric radiograph and automated image analysis for caries or periodontitis, have been performed actively in the last decade. Further developments in digital radiographic imaging modalities, image transmission system, imaging processing and automated analysis software will change the traditional clinical dental practice in the 21st century.

  13. Digital X-ray Imaging in Dentistry

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Kyung [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Dankook University, Yongin (Korea, Republic of)

    1999-08-15

    In dentistry, Radio Visio Graphy was introduced as a first electronic dental x-ray imaging modality in 1989. Thereafter, many types of direct digital radiographic systems have been produced in the last decade. They are based either on charge-coupled device (CCD) or on storage phosphor technology. In addition, new types of digital radiographic system using amorphous selenium, image intensifier etc. are under development. Advantages of digital radiographic system are elimination of chemical processing, reduction in radiation dose, image processing, computer storage, electronic transfer of images and so on. Image processing includes image enhancement, image reconstruction, digital subtraction, etc. Especially digital subtraction and reconstruction can be applied in many aspects of clinical practice and research. Electronic transfer of images enables filmless dental hospital and teleradiology/teledentistry system. Since the first image management and communications system (IMACS) for dentomaxillofacial radiology was reported in 1992, IMACS in dental hospital has been increasing. Meanwhile, researches about computer-assisted diagnosis, such as structural analysis of bone trabecular patterns of mandible, feature extraction, automated identification of normal landmarks on cephalometric radiograph and automated image analysis for caries or periodontitis, have been performed actively in the last decade. Further developments in digital radiographic imaging modalities, image transmission system, imaging processing and automated analysis software will change the traditional clinical dental practice in the 21st century.

  14. Radiation exposure in full-field digital mammography with a flat-panel X-ray detector based on amorphous silicon in comparison with conventional screen-film mammography

    International Nuclear Information System (INIS)

    Hermann, K.P.; Obenauer, S.; Grabbe, E.

    2000-01-01

    Comparison of radiation exposure between a digital amorphous silicon and a screen-film based mammography system. Evaluation of a possible potential of full-field digital mammography in order to decrease the radiation dose. Methods: The average glandular dose for phantom thicknesses from 30 to 60 mm was calculated from experimentally determined entrance surface air kerma for a digital and a conventional mammography system. The effect of reducing the detector dose and of changing the radiation quality on radiation exposure and on image quality were investigated. Results: By using the delivered settings of the automatic exposure control (AEC) devices, both mammographic systems needed nearly the same doses. Regulations and guidelines on radiation doses were complied. With the digital system, a reduction of radiation exposure of up to 40% by using a higher radiation quality and decreasing slightly the detector dose without loss of diagnostic image quality, might be possible. Conclusion: The potential of full-field digital mammography for radiation dose reduction, as shown in the present phantom study, needs however, a careful examination under clinical conditions. (orig.) [de

  15. Selenium for preventing cancer

    Directory of Open Access Journals (Sweden)

    Gabriele Dennert

    Full Text Available BACKGROUND: Selenium is a trace element essential to humans. Higher selenium exposure and selenium supplements have been suggested to protect against several types of cancers. OBJECTIVE: Two research questions were addressed in this review: What is the evidence for: 1. an aetiological relationship between selenium exposure and cancer risk in women and men?; 2. the efficacy of selenium supplementation for cancer prevention in women and men? SEARCH STRATEGY: We searched electronic databases and bibliographies of reviews and included publications. SELECTION CRITERIA: We included prospective observational studies to answer research question (a and randomised controlled trials (RCTs to answer research question (b. DATA COLLECTION AND ANALYSIS: We conducted random effects meta-analyses of epidemiological data when five or more studies were retrieved for a specific outcome. We made a narrative summary of data from RCTs. MAIN RESULTS: We included 49 prospective observational studies and six RCTs. In epidemiologic data, we found a reduced cancer incidence (summary odds ratio, OR, 0.69; 95% confidence interval, CI, 0.53 to 0.91 and mortality (OR 0.55, 95% CI 0.36 to 0.83 with higher selenium exposure. Cancer risk was more pronouncedly reduced in men (incidence: OR 0.66, 95% CI 0.42 to 1.05 than in women (incidence: OR 0.90, 95% CI 0.45 to 1.77. These findings have potential limitations due to study design, quality and heterogeneity of the data, which complicated the interpretation of the summary statistics. The RCTs found no protective efficacy of selenium yeast supplementation against non-melanoma skin cancer or L-selenomethionine supplementation against prostate cancer. Study results for the prevention of liver cancer with selenium supplements were inconsistent and studies had an unclear risk of bias. The results of the Nutritional Prevention of Cancer Trial (NPCT and SELECT raised concerns about possible harmful effects of selenium supplements. AUTHORS

  16. Pressure-induced reversible amorphization and an amorphous-amorphous transition in Ge₂Sb₂Te₅ phase-change memory material.

    Science.gov (United States)

    Sun, Zhimei; Zhou, Jian; Pan, Yuanchun; Song, Zhitang; Mao, Ho-Kwang; Ahuja, Rajeev

    2011-06-28

    Ge(2)Sb(2)Te(5) (GST) is a technologically very important phase-change material that is used in digital versatile disks-random access memory and is currently studied for the use in phase-change random access memory devices. This type of data storage is achieved by the fast reversible phase transition between amorphous and crystalline GST upon heat pulse. Here we report pressure-induced reversible crystalline-amorphous and polymorphic amorphous transitions in NaCl structured GST by ab initio molecular dynamics calculations. We have showed that the onset amorphization of GST starts at approximately 18 GPa and the system become completely random at approximately 22 GPa. This amorphous state has a cubic framework (c-amorphous) of sixfold coordinations. With further increasing pressure, the c-amorphous transforms to a high-density amorphous structure with trigonal framework (t-amorphous) and an average coordination number of eight. The pressure-induced amorphization is investigated to be due to large displacements of Te atoms for which weak Te-Te bonds exist or vacancies are nearby. Upon decompressing to ambient conditions, the original cubic crystalline structure is restored for c-amorphous, whereas t-amorphous transforms to another amorphous phase that is similar to the melt-quenched amorphous GST.

  17. Selenium in Graves' disease

    Directory of Open Access Journals (Sweden)

    Jadwiga Kryczyk

    2013-05-01

    Full Text Available The aim of this study was to present the current state of knowledge of the role of selenium in Graves’ disease. Recently, in the pathogenesis and course of this autoimmune disease, more attention has been paid to the relationship between oxidative stress and the antioxidant system, where selenium compounds play an important role. The thyroid is the organ with the highest selenium concentration in the human body. Selenium compounds, having antioxidant properties, protect thyrocytes against the destructive effects of reactive oxygen species (ROS, which are generated during the synthesis of thyroid hormones. Therefore, strengthening the body’s defense mechanisms, which protect against the formation and activity of ROS during medical treatment of Graves’ disease patients, may be an effective adjuvant in commonly used methods of therapy.

  18. Selenium in diet

    Science.gov (United States)

    ... Prevent certain cancers Protect the body from the poisonous effects of heavy metals and other harmful substances ... garlic are also good sources. Meats produced from animals that ate grains or plants found in selenium- ...

  19. The possibility of using dc conductivity for investigating phase transition in amorphous semiconductors

    International Nuclear Information System (INIS)

    El-Mously, M.K.; Mina, N.K.

    1985-07-01

    Different formulas have been applied to deduce the effective or the generalized electrical conductivity of double phase systems. These formulas have been revised and fitted to the experimental data of the binary systems amorphous-crystal (a-c) and liquid-crystal (l-c) for pure elementary selenium and selenium doped by different other elements. Both connected medium and statistical mixture theories can be applied depending on the nature of the system under investigation. (author)

  20. The effect of dose reduction on image quality in digital radiography using a flat-panel detector: experimental study in rabbits

    International Nuclear Information System (INIS)

    Jung, Sung Il; Goo, Jin Mo; Lee, Hyun Ju; Moon, Woo Kyung; Lim, Kun Young; Cho, Gyung Goo; Kim, Ji Hoon; Im, Jung Gi; Choi, Jang Yong; Nam, Sang Hee

    2005-01-01

    To evaluate the effect of dose reduction on image quality in digital radiography using a flat-panel detector. Digital radiographs of 30 rabbits were obtained at two different dose levels (33.23 μGY for the standard dose group and 20.09 μGY for the reduced dose group). The amorphous selenium-based flat-panel detector system had a panel size of 7 x 8.5 inches, a matrix of 1280 x 1536 (pixels?), and a pixel pitch of 138 μm. Four observers evaluated the soft-copy images on a high-resolution video monitor (2560 x 2048 x 8 bits) in random order. The observers rated the visibility of 13 different anatomic structures on a 5-point scale, viz, the retrocardiac lung, subdiaphragmatic lung, heart border, diaphragmatic border, proximal airway, unobscured lung, liver border, kidney border, bowel gas, flank stripe, ribs, and vertebrae in the mediastinal and abdominal regions. Statistical significance was determined using Wilcoxon's signed rank test. There was no statistically significant difference in the visibility of the anatomic structures on digital radiography between the standard and reduced dose groups. Digital radiography using an amorphous selenium-based flat-panel detector can preserve the image quality, though the dose is reduced to 40% of the standard level

  1. Selenium for preventing cancer.

    Science.gov (United States)

    Vinceti, Marco; Filippini, Tommaso; Del Giovane, Cinzia; Dennert, Gabriele; Zwahlen, Marcel; Brinkman, Maree; Zeegers, Maurice Pa; Horneber, Markus; D'Amico, Roberto; Crespi, Catherine M

    2018-01-29

    This review is the third update of the Cochrane review "Selenium for preventing cancer". Selenium is a naturally occurring element with both nutritional and toxicological properties. Higher selenium exposure and selenium supplements have been suggested to protect against several types of cancer. To gather and present evidence needed to address two research questions:1. What is the aetiological relationship between selenium exposure and cancer risk in humans?2. Describe the efficacy of selenium supplementation for cancer prevention in humans. We updated electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 2), MEDLINE (Ovid, 2013 to January 2017, week 4), and Embase (2013 to 2017, week 6), as well as searches of clinical trial registries. We included randomised controlled trials (RCTs) and longitudinal observational studies that enrolled adult participants. We performed random-effects (RE) meta-analyses when two or more RCTs were available for a specific outcome. We conducted RE meta-analyses when five or more observational studies were available for a specific outcome. We assessed risk of bias in RCTs and in observational studies using Cochrane's risk assessment tool and the Newcastle-Ottawa Scale, respectively. We considered in the primary analysis data pooled from RCTs with low risk of bias. We assessed the certainty of evidence by using the GRADE approach. We included 83 studies in this updated review: two additional RCTs (10 in total) and a few additional trial reports for previously included studies. RCTs involved 27,232 participants allocated to either selenium supplements or placebo. For analyses of RCTs with low risk of bias, the summary risk ratio (RR) for any cancer incidence was 1.01 (95% confidence interval (CI) 0.93 to 1.10; 3 studies, 19,475 participants; high-certainty evidence). The RR for estimated cancer mortality was 1.02 (95% CI 0.80 to 1.30; 1 study, 17,444 participants). For the most frequently

  2. Electrical characteristics of hybrid detector based Gd{sub 2}O{sub 2}S:Tb-Selenium for digital radiation imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sang-Sik [Department of Biomedical Engineering, College of Biomedical Science and Engineering, Inje University, Kimhae, Kyungnam 621-749 (Korea, Republic of); Park, Ji-Koon [Department of Biomedical Engineering, College of Biomedical Science and Engineering, Inje University, Kimhae, Kyungnam 621-749 (Korea, Republic of); Choi, Jang-Yong [Department of Biomedical Engineering, College of Biomedical Science and Engineering, Inje University, Kimhae, Kyungnam 621-749 (Korea, Republic of); Cha, Byung-Yul [Department of Biomedical Engineering, College of Biomedical Science and Engineering, Inje University, Kimhae, Kyungnam 621-749 (Korea, Republic of); Cho, Sung-Ho [Department of Biomedical Engineering, College of Biomedical Science and Engineering, Inje University, Kimhae, Kyungnam 621-749 (Korea, Republic of); Nam, Sang-Hee [Medical Imaging Research Center, Inje University, Kimhae, Kyungnam 621-749 (Korea, Republic of)

    2005-07-01

    Fine Gd{sub 2}O{sub 2}S:Tb powders were synthesized by using a solution-combustion method for a high-resolution digital X-ray imaging detector. The PL spectrum showed that the phosphor was fully crystallized and that the Tb{sup 3+} ions substituted well for the Gd{sup 3+} sites. To investigate the X-ray response of the phosphor, a uniform Gd{sub 2}O{sub 2}S:Tb film was grown using a screen-printing method. The X-ray sensitivities of the 100 {mu}m-Gd{sub 2}O{sub 2}S:Tb/30 {mu}m -Se and 200 {mu}m -Se detector were 470 and 420 pC/cm{sup 2}/mR, respectively, at an electric field of 10 V/{mu}m. The results of the study suggest that the hybrid detector has a significant potential in the application of digital radiography and fluoroscopy systems.

  3. Selenium for preventing cancer

    Science.gov (United States)

    Vinceti, Marco; Dennert, Gabriele; Crespi, Catherine M; Zwahlen, Marcel; Brinkman, Maree; Zeegers, Maurice PA; Horneber, Markus; D'Amico, Roberto; Del Giovane, Cinzia

    2015-01-01

    Background This review is an update of the first Cochrane publication on selenium for preventing cancer (Dennert 2011). Selenium is a metalloid with both nutritional and toxicological properties. Higher selenium exposure and selenium supplements have been suggested to protect against several types of cancers. Objectives Two research questions were addressed in this review: What is the evidence for: an aetiological relation between selenium exposure and cancer risk in humans? andthe efficacy of selenium supplementation for cancer prevention in humans? Search methods We conducted electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL, 2013, Issue 1), MEDLINE (Ovid, 1966 to February 2013 week 1), EMBASE (1980 to 2013 week 6), CancerLit (February 2004) and CCMed (February 2011). As MEDLINE now includes the journals indexed in CancerLit, no further searches were conducted in this database after 2004. Selection criteria We included prospective observational studies (cohort studies including sub-cohort controlled studies and nested case-control studies) and randomised controlled trials (RCTs) with healthy adult participants (18 years of age and older). Data collection and analysis For observational studies, we conducted random effects meta-analyses when five or more studies were retrieved for a specific outcome. For RCTs, we performed random effects meta-analyses when two or more studies were available. The risk of bias in observational studies was assessed using forms adapted from the Newcastle-Ottawa Quality Assessment Scale for cohort and case-control studies; the criteria specified in the Cochrane Handbook for Systematic Reviews of Interventions were used to evaluate the risk of bias in RCTs. Main results We included 55 prospective observational studies (including more than 1,100,000 participants) and eight RCTs (with a total of 44,743 participants). For the observational studies, we found lower cancer incidence (summary odds ratio (OR) 0

  4. Amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-04-01

    Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

  5. Selenium in food and health

    National Research Council Canada - National Science Library

    Reilly, Conor

    2006-01-01

    ...) to be a carcinogen and banned as an additive in food. Selenium is considered by some to be a serious hazard to the environment and to animal health. Selenium-contaminated water has brought deformity and death to wildlife in nature reserves in western USA. There is even concern that because of selenium contamination of soil, crops supplied to the great cities of California could become unfit for human consumption. In large areas of China, endemic selenium toxicity is a hazard for locals who depend on cr...

  6. Binary mixtures of mercury/ selenium, and lead/selenium

    African Journals Online (AJOL)

    Physiologically-based biokinetic models have been developed for predicting simultaneously the Absorption, Distribution, Metabolism and Elimination (ADME) properties of lead (Pb) and selenium (Se), and mercury (Hg) and selenium in a number of target tissues of humans. This was done for three population groups, ...

  7. Reduction of selenite by Azospirillum brasilense with the formation of selenium nanoparticles.

    Science.gov (United States)

    Tugarova, Anna V; Vetchinkina, Elena P; Loshchinina, Ekaterina A; Burov, Andrei M; Nikitina, Valentina E; Kamnev, Alexander A

    2014-10-01

    The ability to reduce selenite (SeO(3)(2-)) ions with the formation of selenium nanoparticles was demonstrated in Azospirillum brasilense for the first time. The influence of selenite ions on the growth of A. brasilense Sp7 and Sp245, two widely studied wild-type strains, was investigated. Growth of cultures on both liquid and solid (2 % agar) media in the presence of SeO(3)(2-) was found to be accompanied by the appearance of the typical red colouration. By means of transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and X-ray fluorescence analysis (XFA), intracellular accumulation of elementary selenium in the form of nanoparticles (50 to 400 nm in diameter) was demonstrated for both strains. The proposed mechanism of selenite-to-selenium (0) reduction could involve SeO(3)(2-) in the denitrification process, which has been well studied in azospirilla, rather than a selenite detoxification strategy. The results obtained point to the possibility of using Azospirillum strains as endophytic or rhizospheric bacteria to assist phytoremediation of, and cereal cultivation on, selenium-contaminated soils. The ability of A. brasilense to synthesise selenium nanoparticles may be of interest to nanobiotechnology for "green synthesis" of bioavailable amorphous red selenium nanostructures.

  8. Developments in digital radiography: an equipment update

    International Nuclear Information System (INIS)

    James, J.J.; O'Connor, P.J.; Davies, A.G.; Cowen, A.R.

    2001-01-01

    Digital X-ray imaging technology has advanced rapidly over the past few years. This review, particularly aimed at those involved in using and purchasing such technology, is an attempt to unravel some of the complexities of this potentially confusing subject. The main groups of X-ray imaging devices that are considered are digitisers of conventional radiographs, image-intensifier-based fluorography systems, photostimulable phosphor computed radiography, amorphous selenium-based technology for thorax imaging and flat-panel systems. As well as describing these different systems, we look at ways of objectively assessing their image quality. Concepts that are used and explained include spatial resolution, grey-scale bit resolution, signal-to-noise ratio and detective quantum efficiency. An understanding of these basic parameters is vital in making a scientific assessment of a system's performance. Image processing and techniques are also briefly discussed, particularly with reference to their potential effects on image quality. This review aims to provide a basic understanding of digital X-ray imaging technology and enables the reader to make an independent and educated assessment of the relative merits of each system. (orig.)

  9. Toxicology of selenium: a review.

    Science.gov (United States)

    Wilber, C G

    1980-09-01

    The concentration of selenium in soil, water, or minerals is site specific. World or regional averages are of little practical value. In one report from the front range area of Colorado, average selenium concentrations in bodies of standing water were from 0.3 to 15.8 micrograms Se per liter of water. In some aquatic organisms there is a strong correlation between the Se content of the water ant that of the body tissues; in others no such correlation obtains. Some organisms bioaccumulate Se by factors as high as 1300 to 3800. In most fish the amount of Se in the flesh seems to depend on the amount in the food taken in; there are exceptions, however. Aquatic organisms from seleniferous regions bioconcentrate selenium so as to reach total body levels of 60 micrograms Se per gram or up to 100 micrograms Se per gram of liver. There seems to be no evidence for "biomagnification" of selenium by aquatic organisms. Selenium exerts a strong protective action against the poisoning effects of many heavy metals (lead, cadmium, arsenic, and mercury, for example) and of some organic toxicants (paraquat, for example) in birds, mammals, and man. Data on man are sketchy. Selenium is released into the environment from the burning of coal. No identifiable hazard to man or to plants and animals useful to man can, at this time, be attributed to this source. Selenium is poisonous to man and animal in large amounts. It is a necessary micronutrient for many animals in small amounts; it may also be a needed micronutrient for man, but the data are sparse. The usual American diet contains adequate selenium for human health. Occupational selenium poisoning is mostly accidental and rare.

  10. Amorphous iron (II) carbonate

    DEFF Research Database (Denmark)

    Sel, Ozlem; Radha, A.V.; Dideriksen, Knud

    2012-01-01

    Abstract The synthesis, characterization and crystallization energetics of amorphous iron (II) carbonate (AFC) are reported. AFC may form as a precursor for siderite (FeCO3). The enthalpy of crystallization (DHcrys) of AFC is similar to that of amorphous magnesium carbonate (AMC) and more...

  11. Sweet chemistry: a green way for obtaining selenium nanoparticles active against cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Adriana P.; Stein, Erika M.; Ferreira, Ana Maria D.C.; Colepicolo, Pio, E-mail: apiresvieira@gmail.com [Universidade de São Paulo (USP), São Paulo-SP (Brazil); Andreguetti, Daniel X.; Cebrián-Torrejón, Gerardo; Doménech-Carbó, Antonio [Departament de Química Analítica, Facultat de Química, Universitat de València, Valencia (Spain)

    2017-07-01

    We present an environment friendly synthesis of selenium nanoparticles and the study of their cytotoxic activity against uterine sarcoma cancer and fibroblasts cells. Amorphous selenium (a-SeNPs) and trigonal selenium (t-SeNPs) were synthesized using D-fructose as the reducing agent and characterized by high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction analysis (XRD), inductively coupled plasma optical emission spectrometry (ICP OES), dynamic light scattering (DLS) to obtain zeta potential values and cyclic voltammetry (CV). Particularly, a-SeNPs presented high toxicity toward the resistant cancer cell line MES-SA/Dx5 and its parental MES-SA line. However, they are not toxic against P4 fibroblast cells in comparative studies. (author)

  12. Phytoremediation of selenium using transgenic plants.

    Science.gov (United States)

    Pilon-Smits, Elizabeth A H; LeDuc, Danika L

    2009-04-01

    Selenium (Se) is a micronutrient for many organisms but also toxic at higher concentrations. Both selenium deficiency and toxicity are serious problems worldwide. Owing to the similarity of selenium to sulfur, plants readily take up and assimilate selenate via sulfur transporters and enzymes and can even volatilize selenium. Selenium accumulating or volatilizing plants may be used for phytoremediation of selenium pollution and as fortified foods. Several transgenic approaches have been used successfully to further enhance plant selenium accumulation, tolerance, and volatilization: upregulation of genes involved in sulfur/selenium assimilation and volatilization, methylation of selenocysteine, and conversion of selenocysteine to elemental Se. Lab and field trials with different transgenic plants have yielded promising results, showing up to ninefold higher levels of selenium accumulation and up to threefold faster volatilization rates.

  13. Mechanism of Selenium Loss in Copper Slag

    Science.gov (United States)

    Desai, Bhavin; Tathavadkar, Vilas; Basu, Somnath

    2018-03-01

    During smelting of copper sulfide concentrate, selenium is distributed between silica-saturated iron-silicate slag and copper-iron sulfide matte. The recovery coefficients of selenium between slag and matte were determined as a function of the initial concentration of selenium at 1523 K (1250 °C) under an inert atmosphere in a vertical tubular furnace. The initial concentration of selenium was varied by the addition of metallic selenium as well as selenium dioxide to the mixture of slag and matte. Analysis of the results indicated high affinity of selenium for matte. The apparent loss of selenium with the slag was attributed to the presence of selenium-enriched matte particles entrapped in the slag, rather than dissolved SeO2. The mechanisms proposed by previous investigators were discussed and also compared with the results of the present investigation.

  14. Trace Element Analysis of Selenium

    International Nuclear Information System (INIS)

    Soliman, M.S.A.

    2010-01-01

    The present thesis divided into four chapters as follows:Chapter (1):This chapter contains an introduction on different oxidation states of organic and inorganic species for selenium in environmental and biological samples, the process for separation of selenium from these samples and the importance of selenium as a component for these samples. Also gives notes about the techniques which are used in the elemental analysis for selenium species and the detection limits for selenium in these techniques, selenium species in human body and the importance of these species in protecting the body from the different types of cancer and the sources of selenium in environmental samples (soil and water) and distribution levels of selenium in these samples.Chapter (2):This chapter is divided into two parts :The first part deals with the sample collection process for environmental samples (underground water, soil) and the wet digestion ( microwave digestion ) process of soil samples. It also contains the theory of work of the closed microwave digestion system.The second part contains detailed information concerning the theoretical considerations of the used analytical techniques. These techniques include Hydride generation - Atomic Absorption Spectrometer (HG-AAS), Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and Neutron Activation Analysis (NAA).Chapter (3): This chapter includes the methods of sampling, sample preparation, and sample digesition. The measures of quality assurance are disscused in this chapter. It describes in details the closed microwave digestion technique and the analytical methods used in this study which are present in Central Laboratory for Elemental and Isotopic Analysis (CLEIA) and the Egypt Second Research Reactor (ETRR-2). The described techniques are Atomic Absorption Spectrometer (AAS 6 vario, Analytical Jena GmbH, Germany), JMS-PLASMAX2 Mass Spectrometer (ICP-MS) and the Egypt Second Research Reactor (NAA).

  15. Hydrogen in amorphous silicon

    International Nuclear Information System (INIS)

    Peercy, P.S.

    1980-01-01

    The structural aspects of amorphous silicon and the role of hydrogen in this structure are reviewed with emphasis on ion implantation studies. In amorphous silicon produced by Si ion implantation of crystalline silicon, the material reconstructs into a metastable amorphous structure which has optical and electrical properties qualitatively similar to the corresponding properties in high-purity evaporated amorphous silicon. Hydrogen studies further indicate that these structures will accomodate less than or equal to 5 at.% hydrogen and this hydrogen is bonded predominantly in a monohydride (SiH 1 ) site. Larger hydrogen concentrations than this can be achieved under certain conditions, but the excess hydrogen may be attributed to defects and voids in the material. Similarly, glow discharge or sputter deposited amorphous silicon has more desirable electrical and optical properties when the material is prepared with low hydrogen concentration and monohydride bonding. Results of structural studies and hydrogen incorporation in amorphous silicon were discussed relative to the different models proposed for amorphous silicon

  16. Selenium Utilization Strategy by Microalgae

    Directory of Open Access Journals (Sweden)

    Hiroya Araie

    2009-11-01

    Full Text Available The diversity of selenoproteins raises the question of why so many life forms require selenium. Selenoproteins are found in bacteria, archaea, and many eukaryotes. In photosynthetic microorganisms, the essential requirement for selenium has been reported in 33 species belonging to six phyla, although its biochemical significance is still unclear. According to genome databases, 20 species are defined as selenoprotein-producing organisms, including five photosynthetic organisms. In a marine coccolithophorid, Emiliania huxleyi (Haptophyta, we recently found unique characteristics of selenium utilization and novel selenoproteins using 75Se-tracer experiments. In E. huxleyi, selenite, not selenate, is the main substrate used and its uptake is driven by an ATP-dependent highaffinity, active transport system. Selenite is immediately metabolized to low-molecular mass compounds and partly converted to at least six selenoproteins, named EhSEP1–6. The most (EhSEP2 and second-most abundant selenoproteins (EhSEP1 are disulfide isomerase (PDI homologous protein and thioredoxin reductase (TR 1, respectively. Involvement of selenium in PDI is unique in this organism, while TR1 is also found in other organisms. In this review, we summarize physiological, biochemical, and molecular aspects of selenium utilization by microalgae and discuss their strategy of selenium utilization.

  17. SELENIUM IN HIGHER PLANTS.

    Science.gov (United States)

    Terry, N.; Zayed, A. M.; De Souza, M. P.; Tarun, A. S.

    2000-06-01

    Plants vary considerably in their physiological response to selenium (Se). Some plant species growing on seleniferous soils are Se tolerant and accumulate very high concentrations of Se (Se accumulators), but most plants are Se nonaccumulators and are Se-sensitive. This review summarizes knowledge of the physiology and biochemistry of both types of plants, particularly with regard to Se uptake and transport, biochemical pathways of assimilation, volatilization and incorporation into proteins, and mechanisms of toxicity and tolerance. Molecular approaches are providing new insights into the role of sulfate transporters and sulfur assimilation enzymes in selenate uptake and metabolism, as well as the question of Se essentiality in plants. Recent advances in our understanding of the plant's ability to metabolize Se into volatile Se forms (phytovolatilization) are discussed, along with the application of phytoremediation for the cleanup of Se contaminated environments.

  18. Characteristics of dual-gate thin-film transistors for applications in digital radiology

    International Nuclear Information System (INIS)

    Waechter, D.; Huang, Z.; Zhao, W.; Blevis, I.; Rowlands, J.A.

    1996-01-01

    A large-area flat-panel detector for digital radiology is being developed. The detector uses an array of dual-gate thin-film transistors (TFTs) to read out X-ray-generated charge produced in an amorphous selenium (a-Se) layer. The TFTs use CdSe as the semiconductor and use the bottom gate for row selection. The top gate can be divided into a 'deliberate' gate, covering most of the channel length, and small 'parasitic' gates that consist of: overlap of source or drain metal over the top-gate oxide; and gap regions in the metal that are covered only by the a-Se. In this paper we present the properties of dual-gate TFTs and examine the effect of both the deliberate and parasitic gates on the detector operation. Various options for controlling the top-gate potential are analyzed and discussed. (author)

  19. Physics of amorphous metals

    CERN Document Server

    Kovalenko, Nikolai P; Krey, Uwe

    2008-01-01

    The discovery of bulk metallic glasses has led to a large increase in the industrial importance of amorphous metals, and this is expected to continue. This book is the first to describe the theoretical physics of amorphous metals, including the important theoretical development of the last 20 years.The renowned authors stress the universal aspects in their description of the phonon or magnon low-energy excitations in the amorphous metals, e.g. concerning the remarkable consequences of the properties of these excitations for the thermodynamics at low and intermediate temperatures. Tunneling

  20. Amorphization within the tablet

    DEFF Research Database (Denmark)

    Doreth, Maria; Hussein, Murtadha Abdul; Priemel, Petra A.

    2017-01-01

    , the feasibility of microwave irradiation to prepare amorphous solid dispersions (glass solutions) in situ was investigated. Indomethacin (IND) and polyvinylpyrrolidone K12 (PVP) were tableted at a 1:2 (w/w) ratio. In order to study the influence of moisture content and energy input on the degree of amorphization......, tablet formulations were stored at different relative humidity (32, 43 and 54% RH) and subsequently microwaved using nine different power-time combinations up to a maximum energy input of 90 kJ. XRPD results showed that up to 80% (w/w) of IND could be amorphized within the tablet. mDSC measurements...

  1. Digital radiography of the thorax

    International Nuclear Information System (INIS)

    Frija, J.; Kerviler, E. de; Zagdanski, A.M.; Feger, C.; Attal, P.; Laval-jeantet, M.

    1997-01-01

    Digital radiography of the thorax can, now be substituted to conventional chest radiography. Computed radiography with phosphor plates and the new selenium detector are emphasized. The major image processing are explained. Successively the main other methods of digital radiography are described: scanning equalization radiography, laser-digitized radiography and multiwire proportional chambers. Then the advantages and the drawbacks of chest computed radiography are extensively reviewed. (author)

  2. INTERIGIONAL VARIABILITY OF THE HUMAN SELENIUM STATUS

    Directory of Open Access Journals (Sweden)

    N. A. Golubkina

    2017-01-01

    Full Text Available Aim of the present work was evaluation of factors affecting interregional variability of the human selenium status.Discussion. Essentiality of selenium to human beings determines the priority of the selenium status evaluation in different regions of the world. At the same time interregional variability of the human selenium status biomarkers are often underestimated. Among factors affecting the human selenium status geochemical characteristic of soils and anthropogenic influence are proved to be the most significant. The importance of seas and oceans are emphasized as important sources of the element. Examples of great interregional variability of the human selenium status are indicated and the importance of complex approach for evaluation of ecological risks connected with inadequate selenium consumption are emphasized. Such an approach should combine the data of selenium distribution in soils, levels of selenium bio concentration by different plants species, selenium content in water, food products and in human biological fluids and tissues. Difficulties in the human selenium status optimization are shown to be typical in regions with significant geochemical variations and intensive anthropogenic loading.Conclusions. High interregional variability of the human selenium status determines the necessity of complex approach in revealing ecological risks connected with selenium deficiency of excess in the environment both in regions with high utilization of local food products and in large industrial regions and towns and also in conditions of separate specific industrial production. 

  3. Progress in digital radiography

    International Nuclear Information System (INIS)

    Cappelle, A.

    2016-01-01

    Because of its practical aspect digital radiography is more and more used in the industrial sector. There are 2 kinds of digital radiography. First, the 'computed radiography' that uses a photon-stimulated screen, and after radiation exposure this screen must be read by an analyser to get a digit image. The second type is the 'direct radiography' that allows one to get a digit radiograph of the object directly. Digital radiography uses the same radioactive nuclides as radiography with silver films: cobalt, iridium or selenium. The spatial resolution of digital radiography is less good than with classical silver film radiography but digital radiography offers a better visual contrast. (A.C.)

  4. Selenium accumulation by plants.

    Science.gov (United States)

    White, Philip J

    2016-02-01

    Selenium (Se) is an essential mineral element for animals and humans, which they acquire largely from plants. The Se concentration in edible plants is determined by the Se phytoavailability in soils. Selenium is not an essential element for plants, but excessive Se can be toxic. Thus, soil Se phytoavailability determines the ecology of plants. Most plants cannot grow on seleniferous soils. Most plants that grow on seleniferous soils accumulate plant species have evolved tolerance to Se, and commonly accumulate tissue Se concentrations >100 mg Se kg(-1) dry matter. These plants are considered to be Se accumulators. Some species can even accumulate Se concentrations of 1000-15 000 mg Se kg(-1 )dry matter and are called Se hyperaccumulators. This article provides an overview of Se uptake, translocation and metabolism in plants and highlights the possible genetic basis of differences in these between and within plant species. The review focuses initially on adaptations allowing plants to tolerate large Se concentrations in their tissues and the evolutionary origin of species that hyperaccumulate Se. It then describes the variation in tissue Se concentrations between and within angiosperm species and identifies genes encoding enzymes limiting the rates of incorporation of Se into organic compounds and chromosomal loci that might enable the development of crops with greater Se concentrations in their edible portions. Finally, it discusses transgenic approaches enabling plants to tolerate greater Se concentrations in the rhizosphere and in their tissues. The trait of Se hyperaccumulation has evolved several times in separate angiosperm clades. The ability to tolerate large tissue Se concentrations is primarily related to the ability to divert Se away from the accumulation of selenocysteine and selenomethionine, which might be incorporated into non-functional proteins, through the synthesis of less toxic Se metabilites. There is potential to breed or select crops

  5. Selenium-containing indolyl compounds

    DEFF Research Database (Denmark)

    Casaril, Angela M; Ignasiak, Marta T; Chuang, Christine Y

    2017-01-01

    materials, including extracellular matrix (ECM) proteins, within the artery wall. Here we investigated the potential of selenium-containing indoles to afford protection against these oxidants, by determining rate constants (k) for their reaction, and quantifying the extent of damage on isolated ECM proteins......Tyr on HCAEC-ECM were also reduced. These data demonstrate that the novel selenium-containing compounds show high reactivity with oxidants and may modulate oxidative and nitrosative damage at sites of inflammation, contributing to a reduction in tissue dysfunction and atherogenesis....

  6. Does selenium supplementation affect thyroid function?

    DEFF Research Database (Denmark)

    Winther, Kristian Hillert; Bonnema, Steen Joop; Cold, Frederik

    2015-01-01

    with placebo, by decreasing serum TSH and FT4 concentrations. Based on these findings, selenium supplementation is not warranted under conditions of marginal selenium deficiency. However, a role for selenium supplementation in the treatment of autoimmune thyroid diseases is still unresolved.......OBJECTIVE: Selenium is present in the active site of proteins important for thyroid hormone synthesis and metabolism. The objective of this study is to investigate the effect of selenium supplementation in different doses on thyroid function, under conditions of suboptimal dietary selenium intake......=0.015), respectively, per 100 μg/day increase, with insignificant differences between 6 months and 5 years. No significant effects were found for FT3 and FT3:FT4 ratio. CONCLUSIONS: In euthyroid subjects, selenium supplementation minutely and dose-dependently affects thyroid function, when compared...

  7. Overwinter survival of mallards fed selenium

    Science.gov (United States)

    Heinz, G.H.; Fitzgerald, M.A.

    1993-01-01

    Adult male mallards (Anas platyrhynchos) were fed diets supplemented with 0, 10, 20, 40, or 80 g/g selenium in the form of selenomethionine. Mortality in each of these treatments was 0, 10, 25, 95, and 100%, respectively, during a 16-week exposure that started in November. After one week of treatment, body weights were significantly depressed by the 20, 40, and 80-ug/g selenium treatments, but not by 10 :g/g selenium. Four weeks after being returned to an untreated diet, the body weight of birds fed 20 ug/g selenium had increased to the point of being statistically inseparable from the weight of controls. Signs of selenium poisoning in the dead included severe emaciation, mottling of the liver, empty gizzard, and the presence of a yellowish fluid around some organs. Concentrations of selenium in blood were related to dietary treatments, but mortality was not clearly related to a threshold concentration of selenium in blood.

  8. Structural amorphous steels

    International Nuclear Information System (INIS)

    Lu, Z.P.; Liu, C.T.; Porter, W.D.; Thompson, J.R.

    2004-01-01

    Recent advancement in bulk metallic glasses, whose properties are usually superior to their crystalline counterparts, has stimulated great interest in fabricating bulk amorphous steels. While a great deal of effort has been devoted to this field, the fabrication of structural amorphous steels with large cross sections has remained an alchemist's dream because of the limited glass-forming ability (GFA) of these materials. Here we report the discovery of structural amorphous steels that can be cast into glasses with large cross-section sizes using conventional drop-casting methods. These new steels showed interesting physical, magnetic, and mechanical properties, along with high thermal stability. The underlying mechanisms for the superior GFA of these materials are discussed

  9. Biomarkers of Selenium Status

    Directory of Open Access Journals (Sweden)

    Gerald F. Combs, Jr.

    2015-03-01

    Full Text Available The essential trace element, selenium (Se, has multiple biological activities, which depend on the level of Se intake. Relatively low Se intakes determine the expression of selenoenzymes in which it serves as an essential constituent. Higher intakes have been shown to have anti-tumorigenic potential; and very high Se intakes can produce adverse effects. This hierarchy of biological activities calls for biomarkers informative at different levels of Se exposure. Some Se-biomarkers, such as the selenoproteins and particularly GPX3 and SEPP1, provide information about function directly and are of value in identifying nutritional Se deficiency and tracking responses of deficient individuals to Se-treatment. They are useful under conditions of Se intake within the range of regulated selenoprotein expression, e.g., for humans <55 μg/day and for animals <20 μg/kg diet. Other Se-biomarkers provide information indirectly through inferences based on Se levels of foods, tissues, urine or feces. They can indicate the likelihood of deficiency or adverse effects, but they do not provide direct evidence of either condition. Their value is in providing information about Se status over a wide range of Se intake, particularly from food forms. There is need for additional Se biomarkers particularly for assessing Se status in non-deficient individuals for whom the prospects of cancer risk reduction and adverse effects risk are the primary health considerations. This would include determining whether supranutritional intakes of Se may be required for maximal selenoprotein expression in immune surveillance cells. It would also include developing methods to determine low molecular weight Se-metabolites, i.e., selenoamino acids and methylated Se-metabolites, which to date have not been detectable in biological specimens. Recent analytical advances using tandem liquid chromatography-mass spectrometry suggest prospects for detecting these metabolites.

  10. Nutrigenetics, nutrigenomics and selenium

    Directory of Open Access Journals (Sweden)

    Lynnette Robiin Ferguson

    2011-04-01

    Full Text Available Selenium (Se is an important micronutrient that, as a component of selenoproteins, influences oxidative and inflammatory processes. Its’ levels vary considerably, with different ethnic and geographic population groups showing varied conditions, ranging from frank Se deficiencies to toxic effects. An optimum Se level is essential for the maintenance of homeostasis, and this optimum may vary according to life stage, general state of health and genotype. Nutrigenetic studies of different Se levels, in the presence of genetic variants in selenoproteins, suggest that an effective dietary Se intake for one individual may be very different from that for others. However, we are just starting to learn the significance of various genes in selenoprotein pathways, functional variants in these, and how to combine such data from genes into pathways, alongside dietary intake or serum levels of Se. Advances in systems biology, genetics and genomics technologies, including genetic/genomic, epigenetic/epigenomic, transcriptomic, proteomic and metabolomic information, start to make it feasible to assess a comprehensive spectrum of the biological activity of Se. Such nutrigenomic approaches may prove very sensitive biomarkers of optimal Se status at the individual or population level. The premature cessation of a major human Se intervention trial has led to considerable controversy as to the value of Se supplementation at the population level. New websites provide convenient links to current information on methodologies available for nutrigenetics and nutrigenomics. These new technologies will increasingly become an essential tool in optimising the level of Se and other micronutrients for optimal health, in individuals and in population groups. However, definitive proof of such effects will require very large collaborative studies, international agreement on study design and innovative approaches to data analysis.

  11. Nutrigenetics, Nutrigenomics, and Selenium

    Science.gov (United States)

    Ferguson, Lynnette R.; Karunasinghe, Nishi

    2011-01-01

    Selenium (Se) is an important micronutrient that, as a component of selenoproteins, influences oxidative and inflammatory processes. Its’ levels vary considerably, with different ethnic and geographic population groups showing varied conditions, ranging from frank Se deficiencies to toxic effects. An optimum Se level is essential for the maintenance of homeostasis, and this optimum may vary according to life stage, general state of health, and genotype. Nutrigenetic studies of different Se levels, in the presence of genetic variants in selenoproteins, suggest that an effective dietary Se intake for one individual may be very different from that for others. However, we are just starting to learn the significance of various genes in selenoprotein pathways, functional variants in these, and how to combine such data from genes into pathways, alongside dietary intake or serum levels of Se. Advances in systems biology, genetics, and genomics technologies, including genetic/genomic, epigenetic/epigenomic, transcriptomic, proteomic, and metabolomic information, start to make it feasible to assess a comprehensive spectrum of the biological activity of Se. Such nutrigenomic approaches may prove very sensitive biomarkers of optimal Se status at the individual or population level. The premature cessation of a major human Se intervention trial has led to considerable controversy as to the value of Se supplementation at the population level. New websites provide convenient links to current information on methodologies available for nutrigenetics and nutrigenomics. These new technologies will increasingly become an essential tool in optimizing the level of Se and other micronutrients for optimal health, in individuals and in population groups. However, definitive proof of such effects will require very large collaborative studies, international agreement on study design, and innovative approaches to data analysis. PMID:22303312

  12. Is the selenium drinking water standard justified?

    Science.gov (United States)

    Lafond, M G; Calabrese, E J

    1979-08-01

    Four cases are presented which suggest that the present U.S.E.P.A. drinking water standard for selenium of 10 micrograms/L in inappropriate. The rationale upon which this standard is based is that selenium is carcinogenic, induces dental caries formation, and is highly toxic to animals. However, a critical assessment of this literature can not support these claims. Case no. 1 demonstrates that there is insufficient evidence to classify selenium as a carcinogen. Data derived from the three respective groups of researchers claiming a carcinogenic effect induced by selenium are obscure due to 1) the inability to accurately identify malignancies, 2) the apparent opposite effects of different selenium compounds, and 3) the lack of proper controls. Case no. 2 reviews recent evidence that selenium reduces the incidence of cancer in laboratory animals and in man, an effect which can probably be attributed to the antioxidant properties of selenium compounds. Case no. 3 provides evidence which does not permit the classification of selenium as a cariogenic element. Epidemiological studies supporting such a claim are inadequate since they lack properly matched control groups. Animal data do not support this link as well. Case no. 4 is a review of studies which clearly demonstrate the essentiality of selenium, an aspect of selenium metabolism that was not considered when the 10 micrograms/L standard was promulgated. In light of the four cases presented and an assessment of selenium toxicity in man, it is concluded that the 10 micrograms/L standard can not be justified. Instead, it is suggested that 50 micrograms/L selenium should provide sufficient protection from the toxic effects of this element. This is consistent with the current state of knowledge with respect to the potential adverse health effects associated with selenium.

  13. Genome-wide association study of serum selenium concentrations

    DEFF Research Database (Denmark)

    Gong, Jian; Hsu, Li; Harrison, Tabitha

    2013-01-01

    Selenium is an essential trace element and circulating selenium concentrations have been associated with a wide range of diseases. Candidate gene studies suggest that circulating selenium concentrations may be impacted by genetic variation; however, no study has comprehensively investigated this ...

  14. Biocompatibility selenium nanoparticles with an intrinsic oxidase-like activity

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Leilei; Huang, Kaixun; Liu, Hongmei, E-mail: hmliu2004@126.com [Huazhong University of Science and Technology, School of Chemistry and Chemical Engineering (China)

    2016-03-15

    Selenium nanoparticles (SeNPs) are considered to be the new selenium supplement forms with high biological activity and low toxicity; however, the molecular mechanism by which SeNPs exert the biological function is unclear. Here, we reported that biocompatibility SeNPs possessed intrinsic oxidase-like activity. Using Na{sub 2}SeO{sub 3} as a precursor and glutathione as a reductant, biocompatibility SeNPs were synthesized by the wet chemical reduction method in the presence of bovine serum albumin (BSA). The results of structure characterization revealed that synthesized SeNPs were amorphous red elementary selenium with spherical morphology, and ranged in size from 25 to 70 nm size with a narrow distribution (41.4 ± 6.7 nm). The oxidase-like activity of the as-synthesized SeNPs was tested with 3,3′,5,5′-tetramethylbenzidine (TMB) as a substrate. The results indicated that SeNPs could catalyze the oxidization of TMB by dissolved oxygen. These SeNPs showed an optimum catalytic activity at pH 4 and 30 °C, and the oxidase-like activity was higher as the concentration of SeNPs increased and the size of SeNPs decreased. The Michaelis constant (K{sub m}) values and maximal reaction velocity (V{sub max}) of the SeNPs for TMB oxidation were 0.0083 mol/L and 3.042 μmol/L min, respectively.

  15. Meaning and resource of selenium in human nutrition

    OpenAIRE

    KRATOCHVÍLOVÁ, Zuzana

    2014-01-01

    Bachelor's thesis concentrates on functions of selenium in human nutrition. Selenium is an essential trace element of importance to human health. Its availability depends on the concentration of selenium in the soil. The average income of selenium in the Czech population are usually 36 g/day per individuals. Excess or insufficient selenium intakes can result in adverse effects on human health. The most important sources of selenium in the diets of most people are meat, fish, eggs, milk, cerea...

  16. Enriched selenium and its effects on growth and biochemical composition in Lactobacillus bulgaricus.

    Science.gov (United States)

    Xia, Shu Kai; Chen, Long; Liang, Jun Qing

    2007-03-21

    Se-enriched Lactobacillus bulgaricus (L. bulgaricus) was generated by administration of sodium selenite (0, 1, 4, 8, 16, 32, and 64 mg/L, respectively) in MRS medium and enriched selenium manifestation in L. bulgaricus was investigated using transmission electron microscopy and energy-dispersive X-ray spectrometry and alterations of essential elements and amino acids in the organism were evaluated. We demonstrate that administration of sodium selenite in the dosage of 1-16 mg/L is suitable for selenium enrichment in L. bulgaricus and can enhance nutritive value in the organism by elevating the contents of essential elements including P, Mg, Mn, Zn, Ca, and total amino acids as well as reducing selenite to insoluble elemental selenium, an electron-dense and amorphous Se (0) granule, thereby depositing it both in the cytoplasm and in the extracellular space of L. bulgaricus. Thus, Se-enriched Lactobacillus can provide a potential dietary source of nontoxic selenium and functional regulator used for food and medical industry.

  17. Three-parameter feedback control of amorphous ribbon magnetization

    Czech Academy of Sciences Publication Activity Database

    Stupakov, Oleksandr; Švec, P.

    2013-01-01

    Roč. 64, č. 3 (2013), s. 166-172 ISSN 0013-578X R&D Projects: GA ČR GP102/09/P108 Institutional support: RVO:68378271 Keywords : magnetic variables measurement * magnetic hysteresis * digital feedback control * amorphous magnetic materials Subject RIV: JB - Sensors, Measurment, Regulation

  18. Serum and urinary selenium levels in thermal injury.

    Science.gov (United States)

    Boosalis, M G; Solem, L D; Ahrenholz, D H; McCall, J T; McClain, C J

    1986-04-01

    Information concerning selenium status in thermal injury patients is limited. Therefore, both serum selenium concentration and 24 h urinary excretion of selenium were evaluated throughout the hospital course for 23 patients with partial and full skin thickness thermal burns. Serum selenium levels were depressed throughout the hospital course in the majority of patients, and only two patients' serum selenium levels had reached the normal range by discharge. Urinary selenium losses were essentially within normal range throughout the same period and thus were not responsible for the observed depression in serum selenium levels. A possible antagonistic relationship between selenium and silver is discussed.

  19. Development of 14' x 8.5' active matrix flat-panel digital x-ray detector system and imaging performance

    International Nuclear Information System (INIS)

    Park, Ji Koon; Choi, Jang Yong; Kang, Sang Sik; Lee, Dong Gil; Seok, Dae Woo; Nam, Sang Hee

    2003-01-01

    Digital radiographic systems based on solid-state detectors, commonly referred to as flat-panel detectors, are gaining popularity in clinical practice. Large area, flat panel solid state detectors are being investigated for digital radiography. The purpose of this work was to evaluate the active matrix flat panel digital x-ray detectors in terms or their modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). In this paper, development and evaluation of a selenium-based flat-panel digital x-ray detector are described. The prototype detector has a pixel pitch of 139 μ m and a total active imaging area of 14 x 8.5 inch 2 giving a total 3.9 million pixels. This detector include a x-ray imaging layer of amorphous selenium as a photoconductor which is evaporated in vacuum state on a TFT flat panel, to make signals in proportion to incident x-ray. The film thickness was about 500 μ m. To evaluate the imaging performance of the digital radiography (DR) system developed in our group, sensitivity, linearity, the modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE) of detector was measured. The measured sensitivity was 4.16 x 10 6 ehp/pixel·mR at the bias field of 10 V/ μ m: The beam condition was 41.9 KeV. Measured MTF at 2.5 lp/mm was 52%, and the DQE at 1.5 lp/mm was 75%. And the excellent linearity was showed where the coefficient of determination (r 2 ) is 0.9693

  20. Development of 14' x 8.5' active matrix flat-panel digital x-ray detector system and imaging performance

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ji Koon; Choi, Jang Yong; Kang, Sang Sik; Lee, Dong Gil; Seok, Dae Woo; Nam, Sang Hee [Medical Imaging Research Center of Inje Univeristy, Kimhae (Korea, Republic of)

    2003-12-15

    Digital radiographic systems based on solid-state detectors, commonly referred to as flat-panel detectors, are gaining popularity in clinical practice. Large area, flat panel solid state detectors are being investigated for digital radiography. The purpose of this work was to evaluate the active matrix flat panel digital x-ray detectors in terms or their modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). In this paper, development and evaluation of a selenium-based flat-panel digital x-ray detector are described. The prototype detector has a pixel pitch of 139 {mu} m and a total active imaging area of 14 x 8.5 inch{sup 2} giving a total 3.9 million pixels. This detector include a x-ray imaging layer of amorphous selenium as a photoconductor which is evaporated in vacuum state on a TFT flat panel, to make signals in proportion to incident x-ray. The film thickness was about 500 {mu} m. To evaluate the imaging performance of the digital radiography (DR) system developed in our group, sensitivity, linearity, the modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE) of detector was measured. The measured sensitivity was 4.16 x 10{sup 6} ehp/pixel{center_dot}mR at the bias field of 10 V/ {mu} m: The beam condition was 41.9 KeV. Measured MTF at 2.5 lp/mm was 52%, and the DQE at 1.5 lp/mm was 75%. And the excellent linearity was showed where the coefficient of determination (r{sup 2}) is 0.9693.

  1. Selenium in ruminant nutrition: a review.

    Science.gov (United States)

    Ammerman, C B; Miller, S M

    1975-10-01

    The early interest in selenium related primarily to its toxicity, but since 1957 the element has been recognized as a dietary essential. The dietary requirement for selenium by most species is about .1 ppm. Deficiencies of selenium in cattle and sheep have been confirmed under natural grazing conditions in many countries of the world. Overt signs of inadequacy such as white muscle disease (nutritional muscular dystrophy) occur primarily in young calves or lambs born to selenium deficient dams. Infertility has increased in ewes grazing pastures low in selenium. In general, signs of deficiency have not occurred in older animals such as finishing beef cattle and lactating dairy cows. Subclinical deficiencies of selenium are not determined easily, however, and thus an inadequacy of the element may be limiting maximum animal performance under certain circumstances of drylot feeding. The current nutritional status of ruminant animals in many geographical areas and involving various feeding programs with this element has not been established. The recent widespread deficiency problems with nonruminants suggest that such an assessment should be made. Concentration of selenium in tissue, particularly in the liver, has been used in establishing selenium status of the animal. With lambs glutathione peroxidase activity in certain tissues may be a more accurate indicator of selenium adequacy than is selenium content of the tissue. Supplemental sodium selenite and sodium selenate by either oral administration or parenteral injection have prevented clinical signs of selenium deficiency and animal losses in both ruminant and nonruminant animals. Heavy pellets containing elemental selenium for placement in the rumen have proved effective. In general, organic forms of selenium are absorbed more readily by animals than are inorganic compounds. The dietary requirements for selenium and its metabolism are influenced by many nutrient interrelationships, including its interactions with

  2. Amorphous Semiconductor Alloys

    Science.gov (United States)

    Madan, Arun

    1985-08-01

    Amorphous silicon (a-Si) based alloys have attracted a considerable amount of interest because of their applications in a wide variety of technologies. However, the major effort has concentrated on inexpensive photovoltaic device applications and has moved from a laboratory curiosity in the early 1970's to viable commercial applications in the 1980's. Impressive progress in this field has been made since the group at University of Dundee demonstrated that a low defect, device quality hydrogenated amorphous silicon (a-Si:H) 12 material could be produced using the radio frequency (r.f.) glow discharge in SiH4 gas ' and that the material could be doped n- and p-type.3 These results spurred a worldwide interest in a-Si based alloys, especially for photovoltaic devices which has resulted in a conversion efficiency approaching 12%. There is now a quest for even higher conversion efficiencies by using the multijunction cell approach. This necessitates the synthesis of new materials of differing bandgaps, which in principle amorphous semiconductors can achieve. In this article, we review some of this work and consider from a device and a materials point of view the hurdles which have to be overcome before this type of concept can be realized.

  3. The x-ray light valve: A potentially low-cost, digital radiographic imaging system-concept and implementation considerations

    International Nuclear Information System (INIS)

    Webster, Christie Ann; Koprinarov, Ivaylo; Germann, Stephen; Rowlands, J. A.

    2008-01-01

    New x-ray radiographic systems based on large-area flat-panel technology have revolutionized our capability to produce digital x-ray images. However, these imagers are extraordinarily expensive compared to the systems they are replacing. Hence, there is a need for a low-cost digital imaging system for general applications in radiology. A novel potentially low-cost radiographic imaging system based on established technologies is proposed--the X-Ray Light Valve (XLV). This is a potentially high-quality digital x-ray detector made of a photoconducting layer and a liquid-crystal cell, physically coupled in a sandwich structure. Upon exposure to x rays, charge is collected on the surface of the photoconductor. This causes a change in the optical properties of the liquid-crystal cell and a visible image is generated. Subsequently, it is digitized by a scanned optical imager. The image formation is based on controlled modulation of light from an external source. The operation and practical implementation of the XLV system are described. The potential performance of the complete system and issues related to sensitivity, spatial resolution, noise, and speed are discussed. The feasibility of clinical use of an XLV device based on amorphous selenium (a-Se) as the photoconductor and a reflective electrically controlled birefringence cell is analyzed. The results of our analysis indicate that the XLV can potentially be adapted to a wide variety of radiographic tasks

  4. Effect of Gamma Radiation on The Microbial Production of Selenium Nanoparticles

    International Nuclear Information System (INIS)

    El Zahaby, D.A.T.M.

    2014-01-01

    Selenium is a trace element commonly found in materials of the earth's crust. Selenium is well known for its photoelectric, semiconductor, free-radical scavenging (HUANG et al., 2003), anti-oxidant(El-Batal et al., 2012 a) and anti-cancer properties(El-Batal et al., 2012 b ; El-Batal et al., 2012 c; Mansour et al., 2010; Zhang et al., 2004). Selenium occurs in different forms as red amorphous selenium (Se 0 ), highly water soluble selenate(SeO 4 2- ) and Selenite(SeO 3 2- ), and as gaseous selenide(Se 2- ). Amongst its various forms, the SeO 3 2- is highly toxic, which adversely affect the cellular respiration and antioxidant system causes protein inactivation and DNA repair inhibition (Dong et al., 2003; Eustice et al., 1981; Turner et al., 1998). Therefore, detoxification of SeO 3 2- has attracted a great deal of attention, particularly the reduction of this oxy anion by the microorganisms(Dwivedi et al., 2013). Most methods used to synthesize selenium nanoparticles (SeNPs) are physical and chemical methods, they are characterized by elevated temperatures, long growth times, high pressures, low yields and are also environmentally hazardous (Li et al., 2007). There is an interesting and exciting biogenic synthesis to prepare SeNPs, the synthesis of SeNPs by biological systems occurs at close to ambient temperatures and pressures and at neutral ph(Bharde et al., 2006). This method is a clean, nontoxic and environmentally friendly procedure. In addition, biological synthesis can present extra advantages over chemical methods such as higher productivity and lower cost (Parikh et al., 2008). Attempts have been made to synthesize SeNPs from such microorganisms as bacteria, fungi (Zare et al., 2013) and yeast (Hariharan et al., 2012). However, a bacterial system is preferred mainly due to reduced time of reaction, ease in handling, and easy genetic manipulation (Wang et al., 2010). The majority of studies on the biogenesis of SeNPs have focused on anaerobic systems

  5. [Administration of selenium in lymphedema].

    Science.gov (United States)

    Kasseroller, R

    1997-09-15

    To investigate the effectiveness and dosage of selenium in the treatment of lymphedema. Intensive treatment with decongestive physical therapy in combination with sodium selenite shows significant improvement in the reduction of the volume of the limb and in the histophysiology of secondary lymphedema after mastectomy or Wertheim-operation. The incidence of skin infections decreased significantly. The anti-inflammatory effect should be considered in the treatment of lymphedema.

  6. Selenium determination by fluorimetric method

    International Nuclear Information System (INIS)

    Lavorenti, A.

    1981-01-01

    A fluorimetric method to determine selenium both in vegetable samples and blood serum is developed. The method consists of a radioisotope 75 Se initially in order to optimize the determination of analytical conditions. Three samples digestion processes and also some factors related to methodology is studied. The nitric-percloric digestion process for 40 samples and the analytical process is shown. (M.J.C.) [pt

  7. Nucleation and growth kinetics of co-deposited copper and selenium precursors to form metastable copper selenides

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, John O.; Anderson, Michael D.; Ngai, Tim; Allen, Thomas [Materials Science Institute and Department of Chemistry, University of Oregon, Eugene, OR 97403 (United States); Johnson, David C., E-mail: davej@uoregon.edu [Materials Science Institute and Department of Chemistry, University of Oregon, Eugene, OR 97403 (United States)

    2011-10-06

    Highlights: > Nucleation and growth of compounds from co-deposited Cu and Se films investigated. > {alpha}-CuSe forms on deposit of films with less than 60% Se. > Metastable cubic CuSe{sub 2} nucleates for Se rich films. > Slow heating rates favor nucleation of metastable cubic CuSe{sub 2} over {gamma}-CuSe. - Abstract: The nucleation and growth kinetics of binary copper-selenium compounds from co-deposited copper and selenium films as a function of annealing temperature and time was investigated. The thermally driven evolution of crystalline phases was followed using differential scanning calorimetry and X-ray diffraction. Below 60% selenium, hexagonal {alpha}-CuSe formed during the deposition and a reversible endothermic transition at {approx}130 deg. C was observed for the phase transition into hexagonal {gamma}-CuSe. Above 60% selenium the samples are amorphous as deposited and there is competition between the formation of {gamma}-CuSe and cubic CuSe{sub 2} as annealing temperature is increased. Slow rates of temperature increase favor the formation of CuSe{sub 2} over {gamma}-CuSe and near 66% selenium only cubic CuSe{sub 2} forms during an exothermic event between 100 deg. C and 110 deg. C. It is surprising that the metastable cubic CuSe{sub 2} initially nucleates and grows rather than the thermodynamically stable orthorhombic CuSe{sub 2} polymorph. Kissinger analysis yields an activation energy for nucleation of 1.6 eV for cubic CuSe{sub 2}. CuSe nucleates throughout the composition region investigated. Hexagonal {alpha}-CuSe reacts with selenium to form the thermodynamically stable orthorhombic polymorph of CuSe{sub 2} as the temperature approaches the melting point of selenium.

  8. The Stabilization of Amorphous Zopiclone in an Amorphous Solid Dispersion.

    Science.gov (United States)

    Milne, Marnus; Liebenberg, Wilna; Aucamp, Marique

    2015-10-01

    Zopiclone is a poorly soluble psychotherapeutic agent. The aim of this study was to prepare and characterize an amorphous form of zopiclone as well as the characterization and performance of a stable amorphous solid dispersion. The amorphous form was prepared by the well-known method of quench-cooling of the melt. The solid dispersion was prepared by a solvent evaporation method of zopiclone, polyvinylpyrrolidone-25 (PVP-25), and methanol, followed by freeze-drying. The physico-chemical properties and stability of amorphous zopiclone and the solid dispersion was studied using differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), hot-stage microscopy (HSM), X-ray diffractometry (XRD), solubility, and dissolution studies. The zopiclone amorphous solid-state form was determined to be a fragile glass; it was concluded that the stability of the amorphous form is influenced by both temperature and water. Exposure of amorphous zopiclone to moisture results in rapid transformation of the amorphous form to the crystalline dihydrated form. In comparison, the amorphous solid dispersion proved to be more stable with increased aqueous solubility.

  9. Selenium in human milk: An Australian study

    International Nuclear Information System (INIS)

    Cumming, F.J.; Fardy, J.J.; Woodward, D.R.

    1991-01-01

    The aims of this Australian study were to determine (total) selenium concentration in breast milk and in maternal blood, and to assess the relationship between the two. The authors also aimed to assess the infants' selenium intake. Twenty lactating women from Brisbane (Queensland) participated in the study, at 6-12 weeks post-partum. Small samples (approximately 10 ml) of breast-milk were manually expressed at the beginning and end of a mid-morning feed, from the first breast offered at that feed. Venous blood samples (10 ml) were also collected from the mothers. Milk and blood samples were analyzed by neutron activation analysis. Babies' milk intake over a 24-hour period was estimated using a modified test-weighing technique. Infant selenium intakes were calculated directly for each infant, using his/her mother's milk selenium level and his/her own 24-hour breast milk intake. The mean selenium concentration in maternal blood was 101 (±SD 19) ng/g and in maternal serum 81 (±15) ng/g. Breast milk selenium concentrations (11.9 ± 3.5 ng/g) were fairly low by international standards. There was no correlation between selenium concentrations in milk and blood (or serum). The infants' 24-hour breast-milk intakes were 856 ± 172 g, and their selenium intakes were 10.7 ± 4.1 μg per day

  10. Learning selenium testing tools with Python

    CERN Document Server

    Gundecha, Unmesh

    2014-01-01

    If you are a quality testing professional, or a software or web application developer looking to create automation test scripts for your web applications, with an interest in Python, then this is the perfect guide for you. Python developers who need to do Selenium testing need not learn Java, as they can directly use Selenium for testing with this book.

  11. Biosynthesis of selenium nanoparticles by Pantoea agglomerans and their antioxidant activity

    Energy Technology Data Exchange (ETDEWEB)

    Torres, S. K.; Campos, V. L., E-mail: vcampos@udec.cl; Leon, C. G. [Universidad de Concepcion, Laboratorio de Microbiologia Ambiental, Departamento de Microbiologia (Chile); Rodriguez-Llamazares, S. M. [Centro de Investigacion de Polimeros Avanzados (CIPA) (Chile); Rojas, S. M.; Gonzalez, M. [Universidad de Concepcion, Laboratorio de Fisiologia Vascular, Departamento de Fisiologia (Chile); Smith, C. [Universidad de Concepcion, Departamento de Microbiologia (Chile); Mondaca, M. A. [Universidad de Concepcion, Laboratorio de Microbiologia Ambiental, Departamento de Microbiologia (Chile)

    2012-11-15

    The bio-reduction of selenite (Se (IV)) generates nanoparticles with sizes ranging between 30 and 300 nm. Biologic properties of Se nanoparticles, e.g., antioxidant activity, are dependent on the nanoparticle size; smaller particles have greater activity. In this study, the bio-reduction of selenite by Pantoea agglomerans strain UC-32 under aerobic conditions and room temperature to produce bioactive Se nanoparticles smaller than 100 nm was demonstrated. Isolation and purification of the nanoparticles was performed by alkaline lysis. These purified nanoparticles were stabilized with l-cysteine (4 mM). The visualization and characterization of nanoparticles were performed by transmission electron microscopy, energy dispersive X-ray spectroscopy, and scanning electron microscopy. The antioxidant activity of nanoparticles was determined by production of reactive oxygen species using human umbilical vein endothelial cells. Transmission electron microscopy images showed the accumulation of spherical selenium nanoparticles as intracellular and extracellular deposits. The size of Se nanoparticles varied with incubation time. Amorphous Se nanoparticles with size in the order of 100 nm were obtained before 24 h of incubation; but, at 24 h of incubation, the size of the majority of the nanoparticles was in the desirable order of 100 nm and they were not aggregated. Energy dispersive spectroscopy spectra indicated that nanoparticles were composed entirely of selenium. Antioxidant activity of stabilized selenium nanoparticles demonstrated high antioxidant activity when compared to selenite and selenium nanoparticles without stabilization. Stabilized biologically synthetized selenium (0) nanoparticles with size less than 100 nm have a potential application as a food additive with antioxidant properties relevant to human health.

  12. Biosynthesis of selenium nanoparticles by Pantoea agglomerans and their antioxidant activity

    Science.gov (United States)

    Torres, S. K.; Campos, V. L.; León, C. G.; Rodríguez-Llamazares, S. M.; Rojas, S. M.; González, M.; Smith, C.; Mondaca, M. A.

    2012-11-01

    The bio-reduction of selenite (Se (IV)) generates nanoparticles with sizes ranging between 30 and 300 nm. Biologic properties of Se nanoparticles, e.g., antioxidant activity, are dependent on the nanoparticle size; smaller particles have greater activity. In this study, the bio-reduction of selenite by Pantoea agglomerans strain UC-32 under aerobic conditions and room temperature to produce bioactive Se nanoparticles smaller than 100 nm was demonstrated. Isolation and purification of the nanoparticles was performed by alkaline lysis. These purified nanoparticles were stabilized with l-cysteine (4 mM). The visualization and characterization of nanoparticles were performed by transmission electron microscopy, energy dispersive X-ray spectroscopy, and scanning electron microscopy. The antioxidant activity of nanoparticles was determined by production of reactive oxygen species using human umbilical vein endothelial cells. Transmission electron microscopy images showed the accumulation of spherical selenium nanoparticles as intracellular and extracellular deposits. The size of Se nanoparticles varied with incubation time. Amorphous Se nanoparticles with size in the order of 100 nm were obtained before 24 h of incubation; but, at 24 h of incubation, the size of the majority of the nanoparticles was in the desirable order of 100 nm and they were not aggregated. Energy dispersive spectroscopy spectra indicated that nanoparticles were composed entirely of selenium. Antioxidant activity of stabilized selenium nanoparticles demonstrated high antioxidant activity when compared to selenite and selenium nanoparticles without stabilization. Stabilized biologically synthetized selenium (0) nanoparticles with size less than 100 nm have a potential application as a food additive with antioxidant properties relevant to human health.

  13. Biosynthesis of selenium nanoparticles by Pantoea agglomerans and their antioxidant activity

    International Nuclear Information System (INIS)

    Torres, S. K.; Campos, V. L.; León, C. G.; Rodríguez-Llamazares, S. M.; Rojas, S. M.; González, M.; Smith, C.; Mondaca, M. A.

    2012-01-01

    The bio-reduction of selenite (Se (IV)) generates nanoparticles with sizes ranging between 30 and 300 nm. Biologic properties of Se nanoparticles, e.g., antioxidant activity, are dependent on the nanoparticle size; smaller particles have greater activity. In this study, the bio-reduction of selenite by Pantoea agglomerans strain UC-32 under aerobic conditions and room temperature to produce bioactive Se nanoparticles smaller than 100 nm was demonstrated. Isolation and purification of the nanoparticles was performed by alkaline lysis. These purified nanoparticles were stabilized with l-cysteine (4 mM). The visualization and characterization of nanoparticles were performed by transmission electron microscopy, energy dispersive X-ray spectroscopy, and scanning electron microscopy. The antioxidant activity of nanoparticles was determined by production of reactive oxygen species using human umbilical vein endothelial cells. Transmission electron microscopy images showed the accumulation of spherical selenium nanoparticles as intracellular and extracellular deposits. The size of Se nanoparticles varied with incubation time. Amorphous Se nanoparticles with size in the order of 100 nm were obtained before 24 h of incubation; but, at 24 h of incubation, the size of the majority of the nanoparticles was in the desirable order of 100 nm and they were not aggregated. Energy dispersive spectroscopy spectra indicated that nanoparticles were composed entirely of selenium. Antioxidant activity of stabilized selenium nanoparticles demonstrated high antioxidant activity when compared to selenite and selenium nanoparticles without stabilization. Stabilized biologically synthetized selenium (0) nanoparticles with size less than 100 nm have a potential application as a food additive with antioxidant properties relevant to human health.

  14. The Role of Selenium in Human Immunity | Chisenga | Medical ...

    African Journals Online (AJOL)

    ... including selenium deficiency, so it has been postulated that selenium has a role in immune function. Immune dysfunction, susceptibility to viral infections and increased mortality are some of the outcomes associated with selenium deficiency. Key Words: Selenium; Human; Cell-mediated immunity; Innate immunity; HIV; ...

  15. Arsenic and selenium in microbial metabolism

    Science.gov (United States)

    Stolz, John F.; Basu, Partha; Santini, Joanne M.; Oremland, Ronald S.

    2006-01-01

    Arsenic and selenium are readily metabolized by prokaryotes, participating in a full range of metabolic functions including assimilation, methylation, detoxification, and anaerobic respiration. Arsenic speciation and mobility is affected by microbes through oxidation/reduction reactions as part of resistance and respiratory processes. A robust arsenic cycle has been demonstrated in diverse environments. Respiratory arsenate reductases, arsenic methyltransferases, and new components in arsenic resistance have been recently described. The requirement for selenium stems primarily from its incorporation into selenocysteine and its function in selenoenzymes. Selenium oxyanions can serve as an electron acceptor in anaerobic respiration, forming distinct nanoparticles of elemental selenium that may be enriched in (76)Se. The biogenesis of selenoproteins has been elucidated, and selenium methyltransferases and a respiratory selenate reductase have also been described. This review highlights recent advances in ecology, biochemistry, and molecular biology and provides a prelude to the impact of genomics studies.

  16. Ranking contributing areas of salt and selenium in the Lower Gunnison River Basin, Colorado, using multiple linear regression models

    Science.gov (United States)

    Linard, Joshua I.

    2013-01-01

    Mitigating the effects of salt and selenium on water quality in the Grand Valley and lower Gunnison River Basin in western Colorado is a major concern for land managers. Previous modeling indicated means to improve the models by including more detailed geospatial data and a more rigorous method for developing the models. After evaluating all possible combinations of geospatial variables, four multiple linear regression models resulted that could estimate irrigation-season salt yield, nonirrigation-season salt yield, irrigation-season selenium yield, and nonirrigation-season selenium yield. The adjusted r-squared and the residual standard error (in units of log-transformed yield) of the models were, respectively, 0.87 and 2.03 for the irrigation-season salt model, 0.90 and 1.25 for the nonirrigation-season salt model, 0.85 and 2.94 for the irrigation-season selenium model, and 0.93 and 1.75 for the nonirrigation-season selenium model. The four models were used to estimate yields and loads from contributing areas corresponding to 12-digit hydrologic unit codes in the lower Gunnison River Basin study area. Each of the 175 contributing areas was ranked according to its estimated mean seasonal yield of salt and selenium.

  17. Blood selenium levels and contribution of food groups to selenium intake in adolescent girls in Iceland

    Directory of Open Access Journals (Sweden)

    Ingibjorg Gunnarsdottir

    2012-08-01

    Full Text Available Background/objectives: Significant changes have been reported in dietary habits and food availability in Iceland that would be expected to compromise selenium intake and status, especially among young people. These include substantial decreases in the consumption of fish and milk, as well as the selenium content of imported wheat. The aim of this study was to assess selenium in the diet and whole blood of adolescent girls, as well as define the most important foods contributing to intake and blood concentrations of selenium. Design: The subjects were 96 randomly selected girls, aged 16–20, who answered a validated food frequency questionnaire (FFQ for dietary assessment. Selenium intake from each food group was calculated in µg/day. Blood samples were collected for measurement of whole blood selenium. Results: Mean dietary selenium was 51±25 µg/day. Milk/dairy products, including cheese, contributed 36±14% of total dietary selenium; fish 18±12%; and bread/cereal products 13±6%. Mean whole blood selenium was 117±12 µg/l (range 90–208; nearly 90% of subjects were above the optimal level of 100 µg/l. Fish and bread/cereal products were the only foods significantly correlated with selenium in blood (r=0.32; P = 0.002 and r=0.22; P = 0.04, respectively while no correlation was found with milk and dairy products in spite of their greater contribution to total selenium intake. Conclusion: In this population of Icelandic adolescent girls, selenium intake and status seem acceptable. Judging from associations between intake and blood levels, fish and cereals may be the most important contributors to blood selenium.

  18. Selenium in Cattle: A Review

    Directory of Open Access Journals (Sweden)

    Youcef Mehdi

    2016-04-01

    Full Text Available This review article examines the role of selenium (Se and the effects of Se supplementation especially in the bovine species. Selenium is an important trace element in cattle. Some of its roles include the participation in the antioxidant defense the cattle farms. The nutritional requirements of Se in cattle are estimated at 100 μg/kg DM (dry matter for beef cattle and at 300 μg/kg DM for dairy cows. The rations high in fermentable carbohydrates, nitrates, sulfates, calcium or hydrogen cyanide negatively influence the organism’s use of the selenium contained in the diet. The Se supplementation may reduce the incidence of metritis and ovarian cysts during the postpartum period. The increase in fertility when adding Se is attributed to the reduction of the embryonic death during the first month of gestation. A use of organic Se in feed would provide a better transfer of Se in calves relative to mineral Se supplementation. The addition of Se yeasts in the foodstuffs of cows significantly increases the Se content and the percentage of polyunsaturated fatty acids (PUFA in milk compared to the addition of sodium selenite. The enzyme 5-iodothyronine deiodinase is a seleno-dependent selenoprotein. It is one of the last proteins to be affected in the event of Se deficiency. This delay in response could explain the fact that several studies did not show the effect of Se supplementation on growth and weight gain of calves. Enrichment of Se in the diet did not significantly affect the slaughter weight and carcass yield of bulls. The impact and results of Se supplementation in cattle depend on physiological stage, Se status of animals, type and content of Se and types of Se administration. Further studies in Se supplementation should investigate the speciation of Se in food and yeasts, as well as understanding their metabolism and absorption. This constitute a path to exploit in order to explain certain different effects of Se.

  19. Selenium in Oncology: From Chemistry to Clinics

    Directory of Open Access Journals (Sweden)

    Oliver Micke

    2009-10-01

    Full Text Available The essential trace element selenium, which is a crucial cofactor in the most important endogenous antioxidative systems of the human body, is attracting more and more the attention of both laypersons and expert groups. The interest of oncologists mainly focuses in the following clinical aspects: radioprotection of normal tissues, radiosensitizing in malignant tumors, antiedematous effect, prognostic impact of selenium, and effects in primary and secondary cancer prevention. Selenium is a constituent of the small group of selenocysteine-containing selenoproteins and elicits important structural and enzymatic functions. Selenium deficiency has been linked to increased infection risk and adverse mood states. It has been shown to possess cancer-preventive and cytoprotective activities in both animal models and humans. It is well established that Se has a key role in redox regulation and antioxidant function, and hence in membrane integrity, energy metabolism and protection against DNA damage. Recent clinical trials have shown the importance of selenium in clinical oncology. Our own clinical study involving 48 patients suggest that selenium has a positive effect on radiation-associated secondary lymphedema in patients with limb edemas, as well as in the head and neck region, including endolaryngeal edema. Another randomized phase III study of our group was performed to examine the cytoprotective properties of selenium in radiation oncology. The aim was to evaluate whether sodium selenite is able to compensate a preexisting selenium deficiency and to prevent radiation induced diarrhea in adjuvant radiotherapy for pelvic gynecologic malignancies. Through this study, the significant benefits of sodium selenite supplementation with regards to selenium deficiency and radiotherapy induced diarrhea in patients with cervical and uterine cancer has been shown for the first time in a prospective randomized trial. Survival data imply that supplementation with

  20. Molecular chemoprevention by selenium: A genomic approach

    International Nuclear Information System (INIS)

    El-Bayoumy, Karam; Sinha, Raghu

    2005-01-01

    Basic research and clinical chemoprevention trials support the protective role of selenium in cancer prevention but the mechanisms based on the molecular level remain to be fully defined. This mini-review focuses only on the elucidation of the molecular mechanisms of cancer prevention by selenium using the genomics approach; target organs discussed here are breast, prostate, colon and lung. The results described here support the utility of microarray technology in delineating the molecular mechanisms of cancer prevention by selenium. These results are based on studies employing human and rodent cell lines and tissues from animal models ranging from normal to frank cancer. The dose and the form of selenium are determining factors in cancer chemoprevention. The results of the microarray analysis reviewed here indicate that selenium, independent of its form and the target organ examined, alters several genes in a manner that can account for cancer prevention. Selenium can up regulate genes related to phase II detoxification enzymes, certain selenium-binding proteins and select apoptotic genes, while down regulating those related to phase I activating enzymes and cell proliferation. Independent of tissue type, selenium arrests cells in G1 phase of cell cycle, inhibits CYCLIN A, CYCLIN D1, CDC25A, CDK4, PCNA and E2F gene expressions while induces the expressions of P19, P21, P53, GST, SOD, NQO1, GADD153 and certain CASPASES. In addition to those described above, genes such as OPN, which is mainly involved in metastasis and recently reported to be down regulated by selenium, should be considered as potential molecular marker in clinical chemoprevention trials. Collectively, literature data indicate that some of these genes that were altered by selenium are also involved in the development of human cancers described in this review. It appears that androgen receptor status may influence the effect of selenium on gene expression profile in prostate cancer; whether estrogen

  1. Selenium-75-labelled foliate compounds

    International Nuclear Information System (INIS)

    1974-01-01

    A saturation method to analyze a foliate is presented; it uses competitive reaction of the compound to be measured and of a radioactive-labelled version of this compound with a reagent specific to this compound present in insufficient quantity to combine with the whole of the compound and its labelled version, separation of the bound compound from its non-bound homologue and measurement of the radioactivity concentration in the bound compound, the non-bound compound or both. The radioactive isotope used in the labelled foliate is selenium 75 [fr

  2. In Situ Immobilization of Selenium in Sediment

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stewart, Thomas Austin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    This project focused on the use of a sorbent, carbonated apatite, to immobilize selenium in the environment. It is know that apatite will sorb selenium and based on the mechanism of sorption it is theorized that carbonated apatite will be more effective that pure apatite. Immobilization of selenium in the environment is through the use of a sorbent in a permeable reactive barrier (PRB). A PRB can be constructed by trenching and backfill with the sorbent or in the case of apatite as the sorbent formed in situ using the apatite forming solution of Moore (2003, 2004). There is very little data on selenium sorption by carbonated apatite in the literature. Therefore, in this work, the basic sorptive properties of carbonated apatite were investigated. Carbonated apatite was synthesized by a precipitation method and characterized. Batch selenium kinetic and equilibrium experiments were performed. The results indicate the carbonated apatite contained 9.4% carbonate and uptake of selenium as selenite was rapid; 5 hours for complete uptake of selenium vs. more than 100 hours for pure hydroxyapatite reported in the literature. Additionally, the carbonated apatite exhibited significantly higher distribution coefficients in equilibrium experiments than pure apatite under similar experimental conditions. The next phase of this work will be to seek additional funds to continue the research with the goal of eventually demonstrating the technology in a field application.

  3. Dietary selenium in the Glasgow area

    International Nuclear Information System (INIS)

    Cross, J.D.; Raie, R.M.; Smith, H.

    1978-01-01

    A typical diet for people in the Glasgow area is analysed and an estimate is made of the daily intake of selenium for the average person (234 μg). Meat, poultry and bread products contribute 65% of the total selenium consumed. There is a significant loss of selenium on cooking but the concentration in the diet is high compared with the estimated requirement. Selenium levels in prepared infant foods, artificial milk and natural milk are reported. Those infants on artificial milk feeds have a selenium intake equivalent to that of adults (3 μg/kg) while those on natural milk or prepared infant foods have an intake of 6 μg/kg. Adult and infant tissue selenium levels are established and are shown to be in equilibrium with the diet. There is no concentration in man as a result of his position at the top of the food chain. Sudden infant death cannot be related to selenium levels in human tissue or diet. (author)

  4. Amorphous Gyroscopic Topological Metamaterials

    Science.gov (United States)

    Mitchell, Noah P.; Nash, Lisa M.; Hexner, Daniel; Turner, Ari M.; Irvine, William T. M.

    Mechanical topological metamaterials display striking mechanical responses, such as unidirectional surface modes that are impervious to disorder. This behavior arises from the topology of their vibrational spectra. All examples of topological metamaterials to date are finely-tuned structures such as crystalline lattices or jammed packings. Here, we present robust recipes for building amorphous topological metamaterials with arbitrary underlying structure and no long-range order. Using interacting gyroscopes as a model system, we demonstrate through experiment, simulation, and theoretical methods that the local geometry and interactions are sufficient to generate topological mobility gaps, allowing for spatially-resolved, real-space calculations of the Chern number. The robustness of our approach enables the design and self-assembly of non-crystalline materials with protected, unidirectional waveguides on the micro and macro scale.

  5. Nuclear transformations studies in selenium isotopes

    International Nuclear Information System (INIS)

    Lopez M, B.E.

    1976-01-01

    A compilation is made with regard to the chemical effects produced by nuclear transformations, such as the chemical effects of the beta decay and the chemical effects of the reaction (n,γ) in selenium radioisotopes. As a particular case the chemical effect of the isomeric transition of sup(81m)Se(VI) in potassium selenate crystals marked with radioactive selenium is studied experimentally and the method of adsorption in activated carbon is applied for the analytical separation of the traces of the nuclear isomer tetravalent sup(81b)Se(IV) of one fraction which contains the mixture of the selenium radioisotopes. (author)

  6. Selenium: environmental significance, pollution, and biological treatment technologies.

    Science.gov (United States)

    Tan, Lea Chua; Nancharaiah, Yarlagadda V; van Hullebusch, Eric D; Lens, Piet N L

    2016-01-01

    Selenium is an essential trace element needed for all living organisms. Despite its essentiality, selenium is a potential toxic element to natural ecosystems due to its bioaccumulation potential. Though selenium is found naturally in the earth's crust, especially in carbonate rocks and volcanic and sedimentary soils, about 40% of the selenium emissions to atmospheric and aquatic environments are caused by various industrial activities such as mining-related operations. In recent years, advances in water quality and pollution monitoring have shown that selenium is a contaminant of potential environmental concern. This has practical implications on industry to achieve the stringent selenium regulatory discharge limit of 5μgSeL(-1) for selenium containing wastewaters set by the United States Environmental Protection Agency. Over the last few decades, various technologies have been developed for the treatment of selenium-containing wastewaters. Biological selenium reduction has emerged as the leading technology for removing selenium from wastewaters since it offers a cheaper alternative compared to physico-chemical treatments and is suitable for treating dilute and variable selenium-laden wastewaters. Moreover, biological treatment has the advantage of forming elemental selenium nanospheres which exhibit unique optical and spectral properties for various industrial applications, i.e. medical, electrical, and manufacturing processes. However, despite the advances in biotechnology employing selenium reduction, there are still several challenges, particularly in achieving stringent discharge limits, the long-term stability of biogenic selenium and predicting the fate of bioreduced selenium in the environment. This review highlights the significance of selenium in the environment, health, and industry and biotechnological advances made in the treatment of selenium contaminated wastewaters. The challenges and future perspectives are overviewed considering recent

  7. Selenium supplementation induces mitochondrial biogenesis in trophoblasts

    Czech Academy of Sciences Publication Activity Database

    Khera, A.; Dong, L. F.; Holland, O.; Vanderlelie, J.; Pasdar, E.A.; Neužil, Jiří; Perkins, A.V.

    2015-01-01

    Roč. 36, č. 8 (2015), s. 363-369 ISSN 0143-4004 Institutional support: RVO:86652036 Keywords : Selenium * Reactive oxygen species * Mitochondrial biogenesis Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.972, year: 2015

  8. Selenium supplementation for critically ill adults

    DEFF Research Database (Denmark)

    Allingstrup, Mikkel; Afshari, Arash

    2015-01-01

    supplementation and number of infections, duration of mechanical ventilation, length of intensive care unit stay and length of hospital stay. SEARCH METHODS: In this update, we searched the current issue of the Cochrane Central Register of Controlled Trials, the Cochrane Library (2014, Issue 5); MEDLINE (Ovid SP...... developing infections (pyrexia, respiratory infections or meningitis) with no obvious benefit (RR 0.60, 95% CI 0.36 to 1.02, 685 participants, very low quality of evidence).Our analyses showed no effect of selenium or ebselen on adverse events (Selenium: RR 1.03, 95% Cl 0.85 to 1.24; six trials, 925...... was originally published in 2004 updated in 2007 and again 2015. OBJECTIVES: The primary objective was to examine the effect of nutrition supplemented with selenium or ebselen on mortality in critically ill patients.The secondary objective was to examine the relationship between selenium or ebselen...

  9. Thioacetamide-induced cirrhosis in selenium-adequate mice displays rapid and persistent abnormity of hepatic selenoenzymes which are mute to selenium supplementation

    International Nuclear Information System (INIS)

    Zhang Jinsong; Wang Huali; Yu Hanqing

    2007-01-01

    Selenium reduction in cirrhosis is frequently reported. The known beneficial effect of selenium supplementation on cirrhosis is probably obtained from nutritionally selenium-deficient subjects. Whether selenium supplementation truly improves cirrhosis in general needs additional experimental investigation. Thioacetamide was used to induce cirrhosis in selenium-adequate and -deficient mice. Selenoenzyme activity and selenium content were measured and the influence of selenium supplementation was evaluated. In Se-adequate mice, thioacetamide-mediated rapid onset of hepatic oxidative stress resulted in an increase in thioredoxin reductase activity and a decrease in both glutathione peroxidase activity and selenium content. The inverse activity of selenoenzymes (i.e. TrxR activity goes up and GPx activity goes down) was persistent and mute to selenium supplementation during the progress of cirrhosis; accordingly, cirrhosis was not improved by selenium supplementation in any period. On the other hand, selenium supplementation to selenium-deficient mice always more efficiently increased hepatic glutathione peroxidase activity and selenium content compared with those treated with thioacetamide, indicating that thioacetamide impairs the liver bioavailability of selenium. Although thioacetamide profoundly affects hepatic selenium status in selenium-adequate mice, selenium supplementation does not modify the changes. Selenium supplementation to cirrhotic subjects with a background of nutritional selenium deficiency can improve selenium status but cannot restore hepatic glutathione peroxidase and selenium to normal levels

  10. Selenium nanoparticles: potential in cancer gene and drug delivery.

    Science.gov (United States)

    Maiyo, Fiona; Singh, Moganavelli

    2017-05-01

    In recent decades, colloidal selenium nanoparticles have emerged as exceptional selenium species with reported chemopreventative and therapeutic properties. This has sparked widespread interest in their use as a carrier of therapeutic agents with results displaying synergistic effects of selenium with its therapeutic cargo and improved anticancer activity. Functionalization remains a critical step in selenium nanoparticles' development for application in gene or drug delivery. In this review, we highlight recent developments in the synthesis and functionalization strategies of selenium nanoparticles used in cancer drug and gene delivery systems. We also provide an update of recent preclinical studies utilizing selenium nanoparticles in cancer therapeutics.

  11. The role of selenium in predicting preeclampsia

    Directory of Open Access Journals (Sweden)

    Z Ghaemi

    2013-10-01

    Full Text Available Introduction: Preeclampsia is a common disorder that is a leading cause of perinatal and maternal morbidity and mortality; however its specific etiology has still remained obscure.The first step in preventing preeclampsia is early detection of women at risk. Since there is no valid and reliable screening test, appropriate diagnostic and screening tests are necessary, which are inexpensive, non-invasive and beneficial for pregnant women. Therefore, regarding the role of selenium as an antioxidant in the prevention preeclampsia, this study was designed which aimed to determine the prognostic value of plasma selenium levels in the diagnosis of preeclampsia in primigravida women Methods: In a nested case control design, a sample of 650 normal primigravida women of 24-28 weeks participated in the study. Subjects who involved the case group were followed up for 3 months and 38 were affected by preeclampsia. Blood samples were obtained from these 38patients as well as from 38 subjects as their matched controls. Moreover, the amount of selenium was measured by atomic absorption spectrometry. Results: The mean level of selenium in blood plasma of the cases was significantly lower than in their matched controls. The present study findings revealed that pregnant women with serum Se < 66.1 μg/L had a significantly increased risk of preeclampsia. Conclusion: Lower plasma selenium level in women destines to suffering from preeclampsia which confirms the destructive effect of selenium deficiency as an antioxidant in etiopathology of preeclampsia. Measurement of plasma selenium can improve the prediction of preeclampsia; thus, it seems that plasma selenium level test owns an acceptable sensitivity and specificity for predicting preeclampsia.

  12. Selenium and tellurium reagents in organic synthesis

    International Nuclear Information System (INIS)

    Comasseto, J.V.

    1984-01-01

    A review of the contribution of the University of Sao Paulo (SP, Brazil) to the organic synthesis of selenium and tellurium reagents is made. Major reactions amoung selenium compounds and insaturated substrates, phosphorus, ester enolates as well as the use of phase transference catalysed reactions to produce arylselenolate are described. For tellurium, interactions of its compounds with organic substrates and reactive intermediates (e.g. benzino diazomethane) are reported. (C.L.B.) [pt

  13. Sound propagation in selenium and tellurium melts

    International Nuclear Information System (INIS)

    Glazov, V.M.; Kim, S.G.; Sulejmenov, T.

    1989-01-01

    Methods, that under similar frequences of ten MHz and using one sample permit to study temperature dependences and propagation velocities, the absorption coefficient of the sound in melts, are described. As a result studying selenium and tellurium melts intricate polytherms of sound propagation velocity and absorption coefficient, that are interpreted usiung representations on breaking chains in associated liquid(selenium) and dissolution of short chains in the melt(tellurium) atomic matrix, are constructed

  14. Kinetically Controlled Two-Step Amorphization and Amorphous-Amorphous Transition in Ice

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chuanlong; Yong, Xue; Tse, John S.; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kenney-Benson, Curtis; Shen, Guoyin

    2017-09-01

    We report the results of in situ structural characterization of the amorphization of crystalline ice Ih under compression and the relaxation of high-density amorphous (HDA) ice under decompression at temperatures between 96 and 160 K by synchrotron x-ray diffraction. The results show that ice Ih transforms to an intermediate crystalline phase at 100 K prior to complete amorphization, which is supported by molecular dynamics calculations. The phase transition pathways show clear temperature dependence: direct amorphization without an intermediate phase is observed at 133 K, while at 145 K a direct Ih-to-IX transformation is observed; decompression of HDA shows a transition to low-density amorphous ice at 96 K and ~ 1 Pa , to ice Ic at 135 K and to ice IX at 145 K. These observations show that the amorphization of compressed ice Ih and the recrystallization of decompressed HDA are strongly dependent on temperature and controlled by kinetic barriers. Pressure-induced amorphous ice is an intermediate state in the phase transition from the connected H-bond water network in low pressure ices to the independent and interpenetrating H-bond network of high-pressure ices.

  15. Selenium levels in neoplastic breast lesions.

    Science.gov (United States)

    Alatise, O I; Babalola, O O; Omoniyi-Esan, G O; Lawal, O O; Adesunkanmi, A R; Agbakwuru, E A

    2013-06-01

    The aim of this prospective case controlled study was to evaluate the tissue levels of selenium in patients with cases of fibroadenoma, cancer of the breast and in the controls in order to relate them to the occurrence of breast diseases. Consecutive consenting patients who had histologically confirmed breast cancer and fibroadenoma attending the General surgical outpatients departments of Obafemi Awolowo University Teaching Hospital Complex, Ile-Ife, were recruited for the study. One gram of core disease breast tissues was taken for Selenium level estimation. There were 127 female subjects;. 95 (74.8%) cases of fibroadenoma and 32 (25.2%) of breast cancer. While breast cancer was common on the left, fibroadenoma was more common on the right breast (? = 8.994; p=0.011). The median tissue level of selenium in patients with fibroadenoma was 0.0272 mg/g with a range of 0.0124 to 0.0576 mg/g and that of the cancer patients was 0.0178 mg/g with a range 0.0072 to 0.0436 mg/g. These were statistically significantly different ( p=0.001). Factors affecting tissue selenium level include age (pbreast cancer (pbreast mass (p=0.023), previous delivery (p=0.004), age at last confinement (p=0.007), parity (pbreast cancer than in fibroadenoma; Tissue selenium inhibits carcinogenesis; low tissue level of selenium therefore may be a factor in the development of breast cancer.

  16. Dietary Selenium and Human Health

    Directory of Open Access Journals (Sweden)

    Lutz Schomburg

    2016-12-01

    Full Text Available Next year (2017, the micronutrient Selenium (Se is celebrating its birthday—i.e., 200 years after first being identified by the Swedish chemist Jöns Jakob Berzelius. Despite its impressive age, research into the functions of this essential trace element is very alive and reaching out for new horizons. This special issue presents some recent fascinating, exciting, and promising developments in Se research in the form of eight original contributions and seven review articles. Collectively, aspects of Se supply, biochemical, physiological, and chemotherapeutic effects, and geobiological interactions are covered by leading scientists in the areas of nutritional, basic, and clinical research. It is obvious from the contributions that the bicentennial anniversary will celebrate a micronutrient still in its infancy with respect to being understood in terms of its biomedical importance.

  17. Structural morphology of amorphous conducting carbon film

    Indian Academy of Sciences (India)

    Unknown

    been found to be having a lot of technological applica- tions. The properties of these amorphous carbons sensi- tively depend on the relative concentration of sp3 and sp2 hybridized carbons. The resulting amorphous materials are variously referred to as tetrahedral amorphous carbon. (ta-C), amorphous carbon (a-C), ...

  18. Amorphous drugs and dosage forms

    DEFF Research Database (Denmark)

    Grohganz, Holger; Löbmann, K.; Priemel, P.

    2013-01-01

    The transformation to an amorphous form is one of the most promising approaches to address the low solubility of drug compounds, the latter being an increasing challenge in the development of new drug candidates. However, amorphous forms are high energy solids and tend to recry stallize. New...... formulation principles are needed to ensure the stability of amorphous drug forms. The formation of solid dispersions is still the most investigated approach, but additional approaches are desirable to overcome the shortcomings of solid dispersions. Spatial separation by either coating or the use of micro......-containers has shown potential to prevent or delay recrystallization. Another recent approach is the formation of co-amorphous mixtures between either two drugs or one drug and one low molecular weight excipient. Molecular interactions between the two molecules provide an energy barrier that has to be overcome...

  19. Selenium Se and tellurium Te

    International Nuclear Information System (INIS)

    Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M.

    1978-01-01

    The basic methods for determining selenium and tellurium in various objects are presented. The bichromatometric determination of Te in cadmium, zinc and mercury tellurides is based on oxidation of Te(4) to (6) in H 2 SO 4 with potassium bichromate. In steels, Te is determined photometrically with the aid of KI. The determination is hindered by Fe(3), Cu(2), Bi(3) and Se(4) ions, which must be separated. The extraction-photometric determination of Te in native sulfur is carried out with the aid of 5-mercapto-3-(naphthyl-2)-1,3,4-thiadiazolthione-2 (pH=4.8-5.0). The dyed complex is readily extracted with chloroform and benzene. The spectrophotometric determination of Te in selenium is performed with the aid of 3,5-diphenylpyrazoline-1-dithiocarbamate of sodium. Te is determined in commercial indium, arsenic and their semiconductor compounds photometrically with the aid of copper diethyldithiocarbamate. The method permits determining 5x10 -5 % Te in a weighed amount of 0.5 g. The chloride complex of Te(4) with diantipyriodolpropylmethane is quantitatively extracted with dichloroethane from hydrochloric acid solutions. Thus, any amounts of Te can be separated from Se and determined photometrically. The extraction-photometric determination of Te in commercial lead and bismuth is carried out with the aid of pyrazolone derivatives, in commercial copper with the aid of diantipyridolpropylmethane, and in ores (more than 0.01% Te) with the aid of bismuthol 2. Also described is the extraction-polarographic determination of Te in sulfide ores

  20. Diamond amorphization in neutron irradiation

    International Nuclear Information System (INIS)

    Nikolaenko, V.A.; Gordeev, V.G.

    1996-01-01

    The paper presents the results on neutron irradiation of the diamond in a nuclear reactor. It is shown that the neutron irradiation stimulates the diamond transition to the amorphous state. At a temperature below 750 o K the time required for the diamond-graphite transition decreases with decreasing irradiation temperature. On the contrary, in irradiation at higher temperatures the time of diamond conversion into the amorphous state increases with decreasing but always remains shorter than in the absence of irradiation. (author)

  1. Anomalous magnetoresistance in amorphous metals

    International Nuclear Information System (INIS)

    Kuz'menko, V.M.; Vladychkin, A.N.; Mel'nikov, V.I.; Sudovtsev, A.I.

    1984-01-01

    The magnetoresistance of amorphous Bi, Ca, V and Yb films is investigated in fields up to 4 T at low temperatures. For all metals the magnetoresistance is positive, sharply decreases with growth of temperature and depends anomalously on the magnetic field strength. For amorphous superconductors the results agree satisfactorily with the theory of anomalous magnetoresistance in which allowance is made for scattering of electrons by the superconducting fluctuations

  2. SELENIUM MOBILITY IN SOME SOILS OF ROMANIA

    Directory of Open Access Journals (Sweden)

    Mihaela Lungu

    2013-12-01

    Full Text Available Selenium mobility in soil depends on a multitude of physical and chemical factors. The present paper highlights the selenium solubilization degree out of the total soil content in relation with its agrochemical properties. Soils samples were considered collected from different agricultural areas of the Country, with or without certain natural handicaps, from soils under industrial impact and long term agrochemical experiments. The selenium solubilization percentages out of the soil total content ranged between 3.57 and 8.15%. No solubilization percentage was calculated for Central and Southern Dobrudja and the South-Eastern Romanian Plane, because the total selenium quantities in these areas are lower and mobile selenium values are very low. The statistical analysis of the calculated percentage values highlighted homogeneous areas and areas with a higher scattering degree. Thus, in agricultural land, in acknowledged agrarian areas and in long term agricultural experiments, the percentage values are better grouped, showing (expectable soil homogeneousness, on one hand, and a significant soil selenium supply and its adequate solubilization for plant nutrition, on the other. The most scattered values occurred in the Călmăţui and Buzău valleys area in halomorphic soils, and in the Făgăraş Depression which is under the industrial polluting influence of chemical works. Among the causes for these differences is the uniformity or non-uniformity of the terrains, induced by land use and the existence or not of a handicap (polluting impact or halomorphic soils, for example. In general, there are no significant differences between the selenium mobility values and their grouping or scattering degree in the soil depth. A single exception stands out, namely in the Făgăraş Depression, where the selenium solubilization degree tends to increase with soil depth, as well as the scattering degree. In the Danube Delta diked areas Sireasa and Pardina very

  3. Hydrogenated amorphous silicon photonics

    Science.gov (United States)

    Narayanan, Karthik

    2011-12-01

    Silicon Photonics is quickly proving to be a suitable interconnect technology for meeting the future goals of on-chip bandwidth and low power requirements. However, it is not clear how silicon photonics will be integrated into CMOS chips, particularly microprocessors. The issue of integrating photonic circuits into electronic IC fabrication processes to achieve maximum flexibility and minimum complexity and cost is an important one. In order to minimize usage of chip real estate, it will be advantageous to integrate in three-dimensions. Hydrogenated amorphous silicon (a-Si:H) is emerging as a promising material for the 3-D integration of silicon photonics for on-chip optical interconnects. In addition, a-Si:H film can be deposited using CMOS compatible low temperature plasma-enhanced chemical vapor deposition (PECVD) process at any point in the fabrication process allowing maximum flexibility and minimal complexity. In this thesis, we demonstrate a-Si:H as a high performance alternate platform to crystalline silicon, enabling backend integration of optical interconnects in a hybrid photonic-electronic network-on-chip architecture. High quality passive devices are fabricated on a low-loss a-Si:H platform enabling wavelength division multiplexing schemes. We demonstrate a broadband all-optical modulation scheme based on free-carrier absorption effect, which can enable compact electro-optic modulators in a-Si:H. Furthermore, we comprehensively characterize the optical nonlinearities in a-Si:H and observe that a-Si:H exhibits enhanced nonlinearities as compared to crystalline silicon. Based on the enhanced nonlinearities, we demonstrate low-power four-wave mixing in a-Si:H waveguides enabling high speed all-optical devices in an a-Si:H platform. Finally, we demonstrate a novel data encoding scheme using thermal and all-optical tuning of silicon waveguides, increasing the spectral efficiency in an interconnect link.

  4. Selenium bioavailability from naturally produced high-selenium peas and oats in selenium-deficient rats.

    Science.gov (United States)

    Yan, Lin; Johnson, LuAnn K

    2011-06-08

    This study determined the bioavailability of selenium (Se) from yellow peas and oats harvested from the high-Se soil of South Dakota, United States. The Se concentrations were 13.5 ± 0.2 and 2.5 ± 0.1 mg/kg (dry weight) for peas and oats, respectively. Male weanling Sprague-Dawley rats were depleted of Se by feeding them a 30% Torula yeast-based diet (4.1 μg Se/kg) for 56 days, and then they were replenished with Se for an additional 50 days by feeding them the same diet supplemented with 20, 30, or 40 μg Se/kg from peas or oats, respectively. Selenium bioavailability was determined on the basis of the restoration of Se-dependent enzyme activities and tissue Se concentrations in Se-depleted rats, comparing those responses for yellow peas and oats to those for l-selenomethionine (SeMet; used as a reference) by using a slope-ratio method. Dietary supplementation with peas or oats resulted in linear or log-linear, dose-dependent increases in glutathione peroxidase activities in blood and liver and in thioredoxin reductase activity in liver. Supplementation with peas or oats resulted in linear or log-linear, dose-dependent increases in Se concentrations of plasma, liver, gastrocnemius muscle, and kidneys. The overall bioavailability was approximately 88% for Se from yellow peas and 92% from oats, compared to SeMet. It was concluded that Se from naturally produced high-Se yellow peas or oats is highly bioavailable in this model and that these high-Se foods may be a good dietary source of Se.

  5. Substoichiometric determination of selenium with potassium ethyl xanthate

    International Nuclear Information System (INIS)

    Chandrasekhar Reddy, P.; Polaiah, B.; Rangamannar, B.

    1989-01-01

    A substoichiometric radiochemical method was developed for the determination of selenium with potassium ethyl xanthate. The selenium ethyl xanthate complex formed was extracted into chloroform from borate buffer at pH 5. The effect of foreign ions on the extraction was studied. Microgram quantities of selenium could be conveniently determined with a fair degree of accuracy. The method was successfully applied for the determination of selenium content in food stuffs such as 'Jaggery' and 'Wheat powder'. (author) 4 refs.; 3 figs

  6. EURRECA—Estimating Selenium Requirements for Deriving Dietary Reference Values

    NARCIS (Netherlands)

    Hurst, R.; Collings, R.; Harvey, L.J.; King, M.; Hooper, L.; Bouwman, J.; Gurinovic, M.; Fairweather-Tait, S.J.

    2013-01-01

    Current reference values for selenium, an essential micronutrient, are based on the intake of selenium that is required to achieve maximal glutathione peroxidase activity in plasma or erythrocytes. In order to assess the evidence of relevance to setting dietary reference values for selenium, the

  7. Selenistasis: Epistatic Effects of Selenium on Cardiovascular Phenotype

    Directory of Open Access Journals (Sweden)

    Joseph Loscalzo

    2013-01-01

    Full Text Available Although selenium metabolism is intricately linked to cardiovascular biology and function, and deficiency of selenium is associated with cardiac pathology, utilization of selenium in the prevention and treatment of cardiovascular disease remains an elusive goal. From a reductionist standpoint, the major function of selenium in vivo is antioxidant defense via its incorporation as selenocysteine into enzyme families such as glutathione peroxidases and thioredoxin reductases. In addition, selenium compounds are heterogeneous and have complex metabolic fates resulting in effects that are not entirely dependent on selenoprotein expression. This complex biology of selenium in vivo may underlie the fact that beneficial effects of selenium supplementation demonstrated in preclinical studies using models of oxidant stress-induced cardiovascular dysfunction, such as ischemia-reperfusion injury and myocardial infarction, have not been consistently observed in clinical trials. In fact, recent studies have yielded data that suggest that unselective supplementation of selenium may, indeed, be harmful. Interesting biologic actions of selenium are its simultaneous effects on redox balance and methylation status, a combination that may influence gene expression. These combined actions may explain some of the biphasic effects seen with low and high doses of selenium, the potentially harmful effects seen in normal individuals, and the beneficial effects noted in preclinical studies of disease. Given the complexity of selenium biology, systems biology approaches may be necessary to reach the goal of optimization of selenium status to promote health and prevent disease.

  8. Selenium deficiency and the effects of supplementation on preterm infants

    Directory of Open Access Journals (Sweden)

    Renata Germano B. O. N. Freitas

    2014-03-01

    Full Text Available Objective: This study aimed to review the literature about blood concentrations of selenium associated with gestational age, feeding, supplementation and related clinical features in preterm infants. Data sources: Systematic review in the following databases: MEDLINE, PubMed, Google academics, SciELO. org, ScienceDirect (Elsevier and CINAHL-Plus with Full Text (EBSCO. Articles published up to January 2013 with the keywords "selenium deficiency", "selenium supplementation", "neonates", "infants", "newborn" and "preterm infants" were selected. Data synthesis: The studies reported that low blood selenium levels are associated with increased risk of respiratory diseases. Preterm infants, especially with low birth weight, presented lower selenium levels. Selenium deficiency has also been associated with the use of oral infant formula, enteral and parenteral nutrition (with or without selenium addition. The optimal dose and length of selenium supplementation is not well-established, since they are based only on age group and selenium ingestion by breastfed children. Furthermore, the clinical status of the infant affected by conditions that may increase oxidative stress, and consequently, selenium requirements is not taken into account. Conclusions: Prematurity and low birth weight can contribute to low blood selenium in premature infants. Selenium supplementation seems to minimize or prevent clinical complications caused by prematurity.

  9. Reduced Maternal Selenium levels in Pregnant and Lactating ...

    African Journals Online (AJOL)

    Reduced Maternal Selenium levels in Pregnant and Lactating Nigerian women: Should Routine Selenium Supplementation be advocated? ... However, there was a non significant increase immediately after birth. In the breast milk, selenium concentration significantly decreased (P<0.0001) as lactation progressed.

  10. Bio-induced solid selenium for recovery from water

    NARCIS (Netherlands)

    Hageman, S.P.W.

    2015-01-01

    Selenium in the form of selenate or selenite in wastewater needs to be removed due to its potential toxicity in the environment. Also, selenium is a valuable element that is used in several industries and current selenium resources are likely to be exhausted in less than 50 years. Waste streams

  11. Toenail mercury and dyslipidemia: Interaction with selenium.

    Science.gov (United States)

    Park, Kyong; Seo, Eunmin

    2017-01-01

    Although compelling evidences from in vivo and in vitro studies exist, limited studies have examined the association between chronic mercury exposure and dyslipidemia. Particularly, data are sparse regarding the influence of selenium on this association of mercury with dyslipidemia in humans. The purpose of the current study was to examine the associations of toenail mercury with dyslipidemia and its components, and to examine whether selenium in toenails modifies these associations. We performed cross-sectional analyses using baseline data from a cohort in the Yeungnam area in South Korea, including 232 men and 269 women. Toenail mercury and selenium concentrations were quantified using neutron activation analysis, and fasting serum lipid measurements were obtained through the medical examination. Odds ratios of the prevalent hypercholesterolemia, hyper-LDL-cholesterolemia, hypo-HDL-cholesterolemia, hypertriglyceridemia, and dyslipidemia in correlation with mercury levels were calculated using multivariable logistic regression. The mean levels of toenail mercury were 0.47μg/g for men and 0.34μg/g for women. After adjustment for multiple confounding variables, participants in the highest tertile of toenail mercury levels had 4.08 (95% CI 1.09-15.32, p for trend=0.02) times higher risk of hyper-LDL-cholesterolemia, and 2.24 (95% CI 1.15-4.37, p for trend=0.004) times higher risk of dyslipidemia than those in the lowest tertile. Selenium is a significant effect-modifier for these associations; the highest tertile of toenail mercury were significantly associated with a higher risk of hypercholesterolemia (OR 5.25, 95% CI 1.04-26.38) and dyslipidemia (OR 2.98, 95% CI 1.16-7.66) compared to the lowest tertile at toenail selenium levels ≤0.685μg/g, while these associations became weak and non-significant, showing OR 0.98 and 95% CI 0.25-3.80 for hypercholesterolemia and OR 1.99 and 95% CI 0.73-5.45 for dyslipidemia at toenail selenium levels >0.685μg/g. We

  12. Selenium in Camel – A Review

    Directory of Open Access Journals (Sweden)

    Bernard Faye

    2009-07-01

    Full Text Available Requirements for trace minerals in camels, particularly selenium, are not well-known. Selenium supplementation using a pharmaceutical form or commercial mineral mixture is common practice in camels to address the cardiomyopathy often attributed to selenium deficiency. This supplementation is often empirical and based on estimated needs for cattle. Nowadays the use of selenium in animal foodstuffs is commonplace and further investigation of its metabolism (ingestion, dynamic of storage-destocking, excretion in camels is warranted. The present review aimed to synthesize all the experimental research (comparative selenium status in cow and camel, response to different levels of supplementation at different physiological stages, excretion maternal transfer, experimental toxicosis and field observations (deficiency, supplementation practices undertaken in camels. The results underline the particularity of the unique metabolic profile of the camel and lead to practical recommendations for supplementation in camels, highlighting its relative sensitivity to excess Se intake at lower levels than in cattle. The maximal tolerable dose is 8 mg and the recommended doses range from 2 to 4 mg.

  13. Speciation of selenium dietary supplements; formation of S-(methylseleno)cysteine and other selenium compounds

    International Nuclear Information System (INIS)

    Amoako, Prince O.; Uden, Peter C.; Tyson, Julian F.

    2009-01-01

    Speciation of selenium is of interest because it is both essential and toxic to humans, depending on the species and the amount ingested. Following indications that selenium supplementation could reduce the incidence of some cancers, selenium-enriched yeast and other materials have been commercialized as supplements. Most dramatically however, the SELECT trial that utilized L-selenomethionine as the active supplement was terminated in 2008 and there is much debate regarding both the planning and the results of efficacy studies. Further, since dietary supplements are not regulated as pharmaceuticals, there are concerns about the quality, storage conditions, stability and selenium content in selenium supplements. Enzymatic hydrolysis enabled selenium speciation profiles to be obtained by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and following derivatization gas chromatography with atomic emission detection (GC-AED). Coated fiber solid phase microextraction (SPME) was used to extract volatile selenium species for determination by GC-AED and GC-MS. Similar speciation patterns were observed between yeast-based supplements subject to extended storage and those heated briefly at elevated temperatures. All the yeast-based supplements and one yeast-free supplement formed S-(methylseleno)cysteine on heating. Evidence was obtained in support of the hypotheses that S-(methylseleno)cysteine is formed from a reaction between dimethyldiselenide and cysteine or cystine.

  14. Speciation of selenium dietary supplements; formation of S-(methylseleno)cysteine and other selenium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Amoako, Prince O. [Department of Chemistry, University of Massachusetts Amherst, 710 N. Pleasant St., Amherst, MA 01003-9336 (United States); Uden, Peter C., E-mail: pcuden@chem.umass.edu [Department of Chemistry, University of Massachusetts Amherst, 710 N. Pleasant St., Amherst, MA 01003-9336 (United States); Tyson, Julian F. [Department of Chemistry, University of Massachusetts Amherst, 710 N. Pleasant St., Amherst, MA 01003-9336 (United States)

    2009-10-12

    Speciation of selenium is of interest because it is both essential and toxic to humans, depending on the species and the amount ingested. Following indications that selenium supplementation could reduce the incidence of some cancers, selenium-enriched yeast and other materials have been commercialized as supplements. Most dramatically however, the SELECT trial that utilized L-selenomethionine as the active supplement was terminated in 2008 and there is much debate regarding both the planning and the results of efficacy studies. Further, since dietary supplements are not regulated as pharmaceuticals, there are concerns about the quality, storage conditions, stability and selenium content in selenium supplements. Enzymatic hydrolysis enabled selenium speciation profiles to be obtained by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and following derivatization gas chromatography with atomic emission detection (GC-AED). Coated fiber solid phase microextraction (SPME) was used to extract volatile selenium species for determination by GC-AED and GC-MS. Similar speciation patterns were observed between yeast-based supplements subject to extended storage and those heated briefly at elevated temperatures. All the yeast-based supplements and one yeast-free supplement formed S-(methylseleno)cysteine on heating. Evidence was obtained in support of the hypotheses that S-(methylseleno)cysteine is formed from a reaction between dimethyldiselenide and cysteine or cystine.

  15. Selenium and Prostate Cancer Prevention: Insights from the Selenium and Vitamin E Cancer Prevention Trial (SELECT

    Directory of Open Access Journals (Sweden)

    Holly L. Nicastro

    2013-04-01

    Full Text Available The Selenium and Vitamin E Cancer Prevention Trial (SELECT was conducted to assess the efficacy of selenium and vitamin E alone, and in combination, on the incidence of prostate cancer. This randomized, double-blind, placebo-controlled, 2 × 2 factorial design clinical trial found that neither selenium nor vitamin E reduced the incidence of prostate cancer after seven years and that vitamin E was associated with a 17% increased risk of prostate cancer compared to placebo. The null result was surprising given the strong preclinical and clinical evidence suggesting chemopreventive activity of selenium. Potential explanations for the null findings include the agent formulation and dose, the characteristics of the cohort, and the study design. It is likely that only specific subpopulations may benefit from selenium supplementation; therefore, future studies should consider the baseline selenium status of the participants, age of the cohort, and genotype of specific selenoproteins, among other characteristics, in order to determine the activity of selenium in cancer prevention.

  16. Impact of Selenium Addition to Animal Feeds on Human Selenium Status in Serbia

    Directory of Open Access Journals (Sweden)

    Zoran Pavlovic

    2018-02-01

    Full Text Available Research conducted during the 1980s demonstrated Se deficiency in humans. Increased inclusion of selenium in animal feeds started from the year 2000 onwards. The aim of this study was to estimate the effects of selenium inclusion in animal feeds on human selenium status and dietary habits of the Serbian population related to food of animal origin. Plasma selenium concentration in healthy adult volunteers, including residents of one of the regions with the lowest (Eastern Serbia, n = 60 and of one of the regions with the highest Se serum levels reported in the past (Belgrade, n = 82, was determined by hydride generation atomic absorption spectrometry. Multivariate analysis was employed to determine the correlation between Se plasma levels and dietary intake data derived from food frequency questionnaires and laboratory tests. The mean plasma Se level of the participants was 84.3 ± 15.9 μg/L (range: 47.3–132.1 μg/L, while 46% of participants had plasma Se levels lower than 80 μg/L. Frequency of meat, egg, and fish consumption was significantly correlated with plasma selenium level (r = 0.437, p = 0.000. Selenium addition to animal feed in the quantity of 0.14 mg/kg contributed to the improvement of human plasma selenium levels by approximately 30 μg/L.

  17. Absorption, distribution, metabolism and excretion of selenium following oral administration of elemental selenium nanoparticles or selenite in rats

    DEFF Research Database (Denmark)

    Löschner, Katrin; Hadrup, Niels; Hansen, Marianne

    2014-01-01

    A suspension of nanoparticles of BSA-stabilized red amorphous elemental selenium (Se) or an aqueous solution of sodium selenite was repeatedly administered by oral gavage for 28 days at 0.05 mg/kg bw/day (low dose) or at 0.5 mg/kg bw/day (high dose) as Se to female rats. Prior to administration...... the concentration of Se was determined by ICP-MS in liver, kidney, urine, feces, stomach, lungs, plasma at µg/g level and in brain and muscle tissue at sub-µg/g level. In order to test if any elemental Se was present in liver, kidney or feces, an in situ derivatization selective to elemental Se was made...... by treatment with sulfite, which resulted in formation of the selenosulfate anion. This Se species was selectively and quantitatively determined by anion exchange HPLC with ICP-MS detection. The results showed that elemental Se was present in the livers, kidneys and feces from animals exposed to low and high...

  18. Effect of image processing version on detection of non-calcification cancers in 2D digital mammography imaging

    Science.gov (United States)

    Warren, L. M.; Cooke, J.; Given-Wilson, R. M.; Wallis, M. G.; Halling-Brown, M.; Mackenzie, A.; Chakraborty, D. P.; Bosmans, H.; Dance, D. R.; Young, K. C.

    2013-03-01

    Image processing (IP) is the last step in the digital mammography imaging chain before interpretation by a radiologist. Each manufacturer has their own IP algorithm(s) and the appearance of an image after IP can vary greatly depending upon the algorithm and version used. It is unclear whether these differences can affect cancer detection. This work investigates the effect of IP on the detection of non-calcification cancers by expert observers. Digital mammography images for 190 patients were collected from two screening sites using Hologic amorphous selenium detectors. Eighty of these cases contained non-calcification cancers. The images were processed using three versions of IP from Hologic - default (full enhancement), low contrast (intermediate enhancement) and pseudo screen-film (no enhancement). Seven experienced observers inspected the images and marked the location of regions suspected to be non-calcification cancers assigning a score for likelihood of malignancy. This data was analysed using JAFROC analysis. The observers also scored the clinical interpretation of the entire case using the BSBR classification scale. This was analysed using ROC analysis. The breast density in the region surrounding each cancer and the number of times each cancer was detected were calculated. IP did not have a significant effect on the radiologists' judgment of the likelihood of malignancy of individual lesions or their clinical interpretation of the entire case. No correlation was found between number of times each cancer was detected and the density of breast tissue surrounding that cancer.

  19. Nanostructures having crystalline and amorphous phases

    Science.gov (United States)

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  20. Fundamentals of amorphous solids structure and properties

    CERN Document Server

    Stachurski, Zbigniew H

    2014-01-01

    Long awaited, this textbook fills the gap for convincing concepts to describe amorphous solids. Adopting a unique approach, the author develops a framework that lays the foundations for a theory of amorphousness. He unravels the scientific mysteries surrounding the topic, replacing rather vague notions of amorphous materials as disordered crystalline solids with the well-founded concept of ideal amorphous solids. A classification of amorphous materials into inorganic glasses, organic glasses, glassy metallic alloys, and thin films sets the scene for the development of the model of ideal amorph

  1. HORMONAL REGULATION OF SELENIUM ACCUMULATION BY PLANTS

    Directory of Open Access Journals (Sweden)

    N. A. Golubkina

    2015-01-01

    Full Text Available Hormonal regulation is considered to be a unique mechanism controlling growth and development of living organism. The review discusses the correlations between pant hormonal status of non-accumulators and hyper-accumulators of Se with the accumulation levels of this microelement. The phenomenon of stimulation and redistribution of selenium as a result of phytohormone treatment, the peculiarities of phytohormones effect among different species and cultivars, and influence of plant sexualization on selenium accumulation are described in article. Data of hormonal regulation of selenium level for spinach, garlic, perennial onion, Brassica chinenesis and Valeriana officialis are presented in the review.

  2. [The role of selenium in endocrine system diseases].

    Science.gov (United States)

    Balázs, Csaba; Rácz, Károly

    2013-10-13

    Oxygen derived free radicals, generated by a number of cellular reactions, include superoxide anion, hydrogen peroxide and hydroxyl radicals. They exert their cytotoxic effects mainly via peroxidation of the cell membrane resulting in the loss of membrane integrity. The essential trace element, selenium exerts complex effects on the endocrine systems, partly due to its antioxidant capacity. Well-characterized selenoproteins include iodothyronine deiodinases, glutathione peroxidases and thioredoxin reductases involved in thyroid hormone metabolism and protection from oxidative damage. The value of selenium supplementation in autoimmune thyroid disorders has been investigated and most studies confirmed the beneficial effect of selenium supplementation in Hashimoto's and Graves's diseases. Recently, selenium proved to be effective in mild inflammatory orbitopathy. There are a number of reports about the effect of selenium in diabetes mellitus, but the data are controversial as both insulin-like and diabetes-inducing effects of selenium have been described. Selenium was successfully used in both female and male infertility of autoimmune origin.

  3. Amorphous nanoparticles — Experiments and computer simulations

    International Nuclear Information System (INIS)

    Hoang, Vo Van; Ganguli, Dibyendu

    2012-01-01

    The data obtained by both experiments and computer simulations concerning the amorphous nanoparticles for decades including methods of synthesis, characterization, structural properties, atomic mechanism of a glass formation in nanoparticles, crystallization of the amorphous nanoparticles, physico-chemical properties (i.e. catalytic, optical, thermodynamic, magnetic, bioactivity and other properties) and various applications in science and technology have been reviewed. Amorphous nanoparticles coated with different surfactants are also reviewed as an extension in this direction. Much attention is paid to the pressure-induced polyamorphism of the amorphous nanoparticles or amorphization of the nanocrystalline counterparts. We also introduce here nanocomposites and nanofluids containing amorphous nanoparticles. Overall, amorphous nanoparticles exhibit a disordered structure different from that of corresponding bulks or from that of the nanocrystalline counterparts. Therefore, amorphous nanoparticles can have unique physico-chemical properties differed from those of the crystalline counterparts leading to their potential applications in science and technology.

  4. Determination of selenium via the fluorescence quenching effect of selenium on hemoglobin-catalyzed peroxidative reaction.

    Science.gov (United States)

    Chen, Ya-Hong; Zhang, Ya-Nan; Tian, Feng-Shou

    2015-05-01

    A new method for the determination of selenium based on its fluorescence quenching on the hemoglobin-catalyzed reaction of H2 O2 and l-tyrosine has been established. The effect of pH, foreign ions and the optimization of variables on the determination of selenium was examined. The calibration curve was found to be linear between the fluorescence quenching (F0 /F) and the concentration of selenium within the range of 0.16-4.00 µg/mL. The detection limit was 1.96 ng/mL and the relative standard deviation was 3.14%. This method can be used for the determination of selenium in Se-enriched garlic bulbs with satisfactory results. Copyright © 2014 John Wiley & Sons, Ltd.

  5. Selenium content in tissues and meat quality in rabbits fed selenium yeast

    Czech Academy of Sciences Publication Activity Database

    Dokoupilová, A.; Marounek, Milan; Skřivanová, V.; Březina, P.

    2007-01-01

    Roč. 52, č. 6 (2007), s. 165-169 ISSN 1212-1819 Institutional research plan: CEZ:AV0Z50450515 Keywords : rabbits * selenium * meat Subject RIV: GH - Livestock Nutrition Impact factor: 0.633, year: 2007

  6. Model for amorphous aggregation processes

    Science.gov (United States)

    Stranks, Samuel D.; Ecroyd, Heath; van Sluyter, Steven; Waters, Elizabeth J.; Carver, John A.; von Smekal, Lorenz

    2009-11-01

    The amorphous aggregation of proteins is associated with many phenomena, ranging from the formation of protein wine haze to the development of cataract in the eye lens and the precipitation of recombinant proteins during their expression and purification. While much literature exists describing models for linear protein aggregation, such as amyloid fibril formation, there are few reports of models which address amorphous aggregation. Here, we propose a model to describe the amorphous aggregation of proteins which is also more widely applicable to other situations where a similar process occurs, such as in the formation of colloids and nanoclusters. As first applications of the model, we have tested it against experimental turbidimetry data of three proteins relevant to the wine industry and biochemistry, namely, thaumatin, a thaumatinlike protein, and α -lactalbumin. The model is very robust and describes amorphous experimental data to a high degree of accuracy. Details about the aggregation process, such as shape parameters of the aggregates and rate constants, can also be extracted.

  7. Amorphous metal matrix composite ribbons

    International Nuclear Information System (INIS)

    Barczy, P.; Szigeti, F.

    1998-01-01

    Composite ribbons with amorphous matrix and ceramic (SiC, WC, MoB) particles were produced by modified planar melt flow casting methods. Weldability, abrasive wear and wood sanding examinations were carried out in order to find optimal material and technology for elevated wear resistance and sanding durability. The correlation between structure and composite properties is discussed. (author)

  8. Atomistic Models of Amorphous Semiconductors

    NARCIS (Netherlands)

    Jarolimek, K.

    2011-01-01

    Crystalline silicon is probably the best studied material, widely used by the semiconductor industry. The subject of this thesis is an intriguing form of this element namely amorphous silicon. It can contain a varying amount of hydrogen and is denoted as a-Si:H. It completely lacks the neat long

  9. High-resolution imaging of selenium in kidneys: a localized selenium pool associated with glutathione peroxidase 3

    Energy Technology Data Exchange (ETDEWEB)

    Malinouski, M.; Kehr, S.; Finney, L.; Vogt, S.; Carlson, B.A.; Seravalli, J.; Jin, R.; Handy, D.E.; Park, T.J.; Loscalzo, J.; Hatfield, D.L.; Gladyshev, V.N. (Harvard-Med)

    2012-04-17

    Recent advances in quantitative methods and sensitive imaging techniques of trace elements provide opportunities to uncover and explain their biological roles. In particular, the distribution of selenium in tissues and cells under both physiological and pathological conditions remains unknown. In this work, we applied high-resolution synchrotron X-ray fluorescence microscopy (XFM) to map selenium distribution in mouse liver and kidney. Liver showed a uniform selenium distribution that was dependent on selenocysteine tRNA{sup [Ser]Sec} and dietary selenium. In contrast, kidney selenium had both uniformly distributed and highly localized components, the latter visualized as thin circular structures surrounding proximal tubules. Other parts of the kidney, such as glomeruli and distal tubules, only manifested the uniformly distributed selenium pattern that co-localized with sulfur. We found that proximal tubule selenium localized to the basement membrane. It was preserved in Selenoprotein P knockout mice, but was completely eliminated in glutathione peroxidase 3 (GPx3) knockout mice, indicating that this selenium represented GPx3. We further imaged kidneys of another model organism, the naked mole rat, which showed a diminished uniformly distributed selenium pool, but preserved the circular proximal tubule signal. We applied XFM to image selenium in mammalian tissues and identified a highly localized pool of this trace element at the basement membrane of kidneys that was associated with GPx3. XFM allowed us to define and explain the tissue topography of selenium in mammalian kidneys at submicron resolution.

  10. The relation between relaxed enthalpy and volume during physical aging of amorphous polymers and selenium

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Říha, Pavel; Rychwalski, R. W.; Emri, I.; Sáha, P.; Kubát, J.

    2006-01-01

    Roč. 42, č. 10 (2006), s. 2824-2837 ISSN 0014-3057 R&D Projects: GA AV ČR IAA2060401 Institutional research plan: CEZ:AV0Z20600510 Keywords : Enthalpy relaxation * Polymer aging Subject RIV: BJ - Thermodynamics Impact factor: 2.113, year: 2006

  11. Optical and vibrational properties of sulfur and selenium versus halogens in hydrogenated amorphous silicon matrix

    International Nuclear Information System (INIS)

    Al-Alawi, S.M.; Al-Dallal, S.

    1999-01-01

    The infrared spectra of a compositional variation series of alpha-Si,S:H; alpha-Si,Se:H, alpha-Si:Cl, H and alpha-Si:F,H thin films were deposited by r.f. glow discharge were compared. It was shown that S, Se, Cl and F can be bonded to the silicon matrix. The stretching mode bands at 2000 cm/sup -1/. and 2100 cm/sup -1/ in the infrared spectra of the above alloys shifts systematically to higher wave numbers when incorporated S,Se or halogen atoms are increases. This observation was attributed to the larger electronegativity of these atoms with respect to the host matrix. Optical transmission spectroscopy and photothermal deflection experiments reveal an increase in the band gap when the content of any of the above elements is increased. However, the highest band gap was obtained for sulfur alloys. This result was interpreted in terms of the S-Si bond strength as compared to other elements. It was found that alpha-Si, S:H was interpreted in terms of the S-Si alloys exhibit the highest structural stability among the four alloys for moderate amount of incorporated sulfur atoms. (author)

  12. Electrical Properties Of Amorphous Selenium (aSe)/p-Type Silicon ...

    African Journals Online (AJOL)

    The electrical conductivity in annealed junction is lower than in its unannealed counterpart for devices fabricated on pSi crystals having the same surface orientation. Barrier heights obtained in junctions fabricated on pSi (100) crystals are larger than barrier heights on pSi (111) crystals. KEY WORDS: Heterojunction , device ...

  13. The Relationship between Selenium and T3 in Selenium Supplemented and Nonsupplemented Ewes and Their Lambs

    Directory of Open Access Journals (Sweden)

    Abd Elghany Hefnawy

    2014-01-01

    Full Text Available Twenty pregnant ewes were selected and classified into two groups. The first group received subcutaneous selenium supplementation (0.1 mg of sodium selenite/kg BW at the 8th and 5th weeks before birth and 1st week after birth while the other was control group without selenium injection. Maternal plasma and serum samples were collected weekly from the 8th week before birth until the 8th week after birth and milk samples were taken from ewes weekly, while plasma and serum samples were collected at 48 hours, 1st, 2nd, 3rd, 5th, and 8th weeks after birth from the newborn lambs. Results demonstrated significant positive relationship between maternal plasma selenium and serum T3 in supplemented and control ewes (r=0.69 to 0.72, P<0.05. There was significant (P<0.001 increase in T3 in supplemented ewes and their lambs until the 8th week after birth. There was positive relationship between milk, selenium concentration, and serum T3 in the newborn lambs of the supplemented group (r=0.84, P<0.01, while the relationship was negative in the control one (r=-0.89, P<0.01. Muscular and thyroid pathological changes were independent of selenium supplementation. Selenium supplementation was important for maintaining T3 in ewes and newborn lambs until the 8th week after birth.

  14. Speciation of selenium and arsenic in natural waters and sediments. Volume 1. Selenium speciation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cutter, G.A.

    1986-06-01

    Fossil fuel combustion can lead to an increased mobilization of selenium to the aquatic environment. In order to examine this process, the different chemical forms of selenium must be determined in water and sediments with high degrees of accuracy and precision. A selective hydride generation procedure was developed to measure the concentrations of dissolved selenite, selenate, total selenium, and organic selenides in natural waters. Two detetor systems were valuated, atomic absorption with quartz tube - air/hydrogen flame atomization, and gas chromatography with photo ionization detection. Results show that the photo ionization system has a high detection limit (10 ng Se), and a non-linear response. In contrast, the atomic absorption technique is able to detect 0.2 ng Se, and the instrumental response is linear to 96 ng Se. For the determination of selenium speciation, the precision (as relative standard deviation) is no greater than 5.4%; accuracy is assured using the standard additions method of calibration. In sediments, total selenium is solubilized using an oxidative digest, and a sodium hydroxide leach releases sedimentary selenite and selenate. Solutions from these pretreatments are analyzed using the dissolved selenium methods.

  15. Image Quality and Radiation Dose Assessment of a Digital Mammography System

    International Nuclear Information System (INIS)

    Isa, N. M.; Hassan, W. M. S. W.; Abdullah, W. A. K. W.; Othman, F.; Ramli, A. A. M.

    2010-01-01

    Image quality and radiation dose of a direct amorphous selenium digital mammography system were considered in terms of contrast to noise ratio (CNR) and average glandular dose (AGD). They were measured for various qualities and breast phantom thicknesses with different types of breast tissue composition to determine optimal radiation quality and dose. Three sets of breast tissue equivalent slabs (30%:70%, 50%:50% and 70%:30% glandular-adipose) with thickness of 2 cm to 7 cm and 0.2 mm aluminum foil were used to provide certain CNR. Two different combinations of anode/ilter material and a wide range of tube voltages were employed for each phantom thickness. Phantom images with grid were acquired using automatic exposure control (AEC) mode for each thickness. Phantom images without grid were also obtained in manual exposure mode by selecting the same anode/filter combination and kVp as the image obtained with grid at the same thickness, but varying mAs of 10 to 200 mAs. Optimization indicated that relatively high energy beam qualities should be used with a greater dose to compensate for lower energy x-rays. The results also indicate that current AEC setting for a fixed detector is not optimal.

  16. 21 CFR 573.920 - Selenium.

    Science.gov (United States)

    2010-04-01

    ... reproduction of livestock and poultry; and (5) the manufacture and use of selenium at such levels cannot... follows: (1) In complete feed for chickens, swine, turkeys, sheep, cattle, and ducks at a level not to exceed 0.3 part per million. (2) In feed supplements for limit feeding as follows: (i) Sheep: At a level...

  17. Ameliorative effects of selenium and zinc

    African Journals Online (AJOL)

    Methidathion-induced hematological, biochemical and hepatohistological alterations in rat: Ameliorative effects of selenium and zinc. ... In contrast, reduced glutathione level (GSH), and the activities of catalase (CAT), superoxide dismutase (SOD), and the glutathione peroxidase (GPx) content of hepatic tissue decreased ...

  18. Selenium speciation in anaerobic granular sludge

    NARCIS (Netherlands)

    Lenz, M.; Gmerek, A.; Lens, P.N.L.

    2006-01-01

    Chromatographic (IC-CD, GC-FID) and spectroscopic (XRD) techniques that allow the specific determination of several selenium species present or formed during bioremediation processes of selenate contaminated drinking, ground, or wastewaters have been established. The developed techniques are shown

  19. Radio protective effects of selenium on rats

    International Nuclear Information System (INIS)

    Bakir, A.; Alya, G

    2005-11-01

    Potential radio-protective effects of different selenium supplement concentrations of 4, 8, 15 and 30 ppm were evaluated in rats. Four groups of rats were administered different concentrations of selenium in drinking water for 30 days before irradiation starting from the ablactation which considered as day 0. The results showed that the sodium selenite of 4 ppm and 8 ppm enhance the 30-day survival of irradiated rats at 7 Gy ( sup 6 sup 0 Co source, whole body irradiation dose rate of 1 Gy x min sup - sup 1) compared to the control group. The mean cumulated probability of survival of rats was 69%+-6 (mean+-S.E.) and 77%+-6 in 4 and 8 ppm groups, respectively, versus 42%+-9 for control group (P<0.001). It was also indicated that sodium selenite with concentrations of 15 and 30 ppm had no significant reduction in mortality. The mean cumulated probability of survival of rats was 50%+-12 (P=0.39) and 49%+-14 (P=0.04), respectively. The toxic effects of selenium were observed at 15 ppm and 30 ppm, survivals after 30 days of selenium intake were 76% and 46%, respectively. It was concluded that 4 and 8 ppm sodium selenite have a radio-protective effect. 15 and 30 ppm sodium selenite had no radio-protective effects in rats, this may be due to a synergism of toxicity and radiation effects. (author)

  20. Recovery of stream communities from experimental selenium exposure

    Energy Technology Data Exchange (ETDEWEB)

    Swift, M.C.; Kuklinskal, B.; Ferkull, K. [Univ. of Minnesota, Monticello, MN (United States); Allen, K.N.; Hermanutz, R.O.; Roush, T.H.; Hedtke, S.F. [Environmental Protection Agency, Duluth, MN (United States). Environmental Research Lab.

    1994-12-31

    The effects of selenium on stream communities and their recovery from those effects were studied at MERS from 1987--1991. Selenium was dosed into two replicate streams each at concentrations of 30, 10, 2.5 and 0 (control) {mu}g L{sup {minus}1} for 18, 30, and 12 months, respectively. Recovery was monitored for three (30) or two (1 0, 2.5) years following cessation of selenium dosing. Selenium rapidly accumulated in the sediment, plants, macroinvertebrates and fish during dosing. Selenium concentrations in sediment, macroinvertebrates, and plants were as high as 2X--4X, 2X--4X, and 1X--1OX the dosed concentration in the 30, 10, and 2.5 treatments, respectively. Selenium decreased relatively rapidly following cessation of dosing. By two years after dosing ceased, selenium concentrations in plants and macroinvertebrates were little different from the controls; selenium in sediment from the 30 and 10 streams was still higher than in the control streams two years after dosing ceased. The macroinvertebrate community changed little during the dosing and recovery period. Commonly used indices of community structure showed no effect of selenium dosing. The isopod Asellus and oligochaetes in the family Tubificidae decreased rapidly following the onset of selenium dosing; their recovery following cessation of dosing was slow.

  1. Selenium and the thyroid gland: more good news for clinicians.

    Science.gov (United States)

    Drutel, Anne; Archambeaud, Françoise; Caron, Philippe

    2013-02-01

    The thyroid is the organ with the highest selenium content per gram of tissue because it expresses specific selenoproteins. Since the discovery of myxoedematous cretinism and thyroid destruction following selenium repletion in iodine- and selenium-deficient children, data on links between thyroid metabolism and selenium have multiplied. Although very minor amounts of selenium appear sufficient for adequate activity of deiodinases, thus limiting the impact of its potential deficiency on synthesis of thyroid hormones, selenium status appears to have an impact on the development of thyroid pathologies. The value of selenium supplementation in autoimmune thyroid disorders has been emphasized. Most authors attribute the effect of supplementation on the immune system to the regulation of the production of reactive oxygen species and their metabolites. In patients with Hashimoto's disease and in pregnant women with anti-TPO antibodies, selenium supplementation decreases anti-thyroid antibody levels and improves the ultrasound structure of the thyroid gland. Although clinical applications still need to be defined for Hashimoto's disease, they are very interesting for pregnant women given that supplementation significantly decreases the percentage of postpartum thyroiditis and definitive hypothyroidism. In Graves' disease, selenium supplementation results in euthyroidism being achieved more rapidly and appears to have a beneficial effect on mild inflammatory orbitopathy. A risk of diabetes has been reported following long-term selenium supplementation, but few data are available on the side effects associated with such supplementation and further studies are required. © 2012 Blackwell Publishing Ltd.

  2. Thyroid hormones regulate selenoprotein expression and selenium status in mice.

    Directory of Open Access Journals (Sweden)

    Jens Mittag

    Full Text Available Impaired expression of selenium-containing proteins leads to perturbed thyroid hormone (TH levels, indicating the central importance of selenium for TH homeostasis. Moreover, critically ill patients with declining serum selenium develop a syndrome of low circulating TH and a central downregulation of the hypothalamus-pituitary-thyroid axis. This prompted us to test the reciprocal effect, i.e., if TH status would also regulate selenoprotein expression and selenium levels. To investigate the TH dependency of selenium metabolism, we analyzed mice expressing a mutant TH receptor α1 (TRα1+m that confers a receptor-mediated hypothyroidism. Serum selenium was reduced in these animals, which was a direct consequence of the mutant TRα1 and not related to their metabolic alterations. Accordingly, hyperthyroidism, genetically caused by the inactivation of TRβ or by oral TH treatment of adult mice, increased serum selenium levels in TRα1+m and controls, thus demonstrating a novel and specific role for TRα1 in selenium metabolism. Furthermore, TH affected the mRNA levels for several enzymes involved in selenoprotein biosynthesis as well as serum selenoprotein P concentrations and the expression of other antioxidative selenoproteins. Taken together, our results show that TH positively affects the serum selenium status and regulates the expression of several selenoproteins. This demonstrates that selenium and TH metabolism are interconnected through a feed-forward regulation, which can in part explain the rapid parallel downregulation of both systems in critical illness.

  3. Monodispersed spherical shaped selenium nanoparticles (SeNPs) synthesized by Bacillus subtilis and its toxicity evaluation in zebrafish embryos

    Science.gov (United States)

    Chandramohan, Subburaman; Sundar, Krishnan; Muthukumaran, Azhaguchamy

    2018-02-01

    Selenium is one of the essential elements involved in antioxidative and antiinflammatory effects in human body. By naturally, selenium ions are metabolised and converted into nano selenium. Now a days there is an increasing attention on applications of nanoparticles in therapeutic field. In the present study Bacillus subtilis was used to convert sodium selenite to SeNPs. The synthesized SeNPs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X ray spectroscopy (EDX). The presence of SeNPs was confirmed by the formation of red colour. The bands were sharp with broad absorption peaks at 3562 cm‑1 and 1678‑1 cm in FTIR which showed that the bacterial proteins were responsible for the reduction of sodium selenite to SeNPs. The average size of the SeNPs was 334 nm and were spherical in shape with uniform distribution. The XRD data confirmed that SeNPs were of amorphous in nature. The zeta potential of SeNPs was negative in charge which indicated high stability. In the present study zebrafish embryos were used to study the toxicity of SeNPs and the results showed that the concentration beyond 10 μg ml‑1 leads to toxic effects in embryos/hatchlings. The lesser concentration of SeNPs can be useful in various biomedical applications.

  4. Bioavailability of selenium from fish, yeast and selenate: A comparative study in humans using stable isotopes

    NARCIS (Netherlands)

    Fox, T.E.; Heuvel, E.G.H.M. van den; Atherton, C.A.; Dainty, J.R.; Lewis, D.J.; Langford, N.J.; Crews, H.M.; Luten, J.B.; Lorentzen, M.; Sieling, F.W.; Aken-Schneyder, P. van; Hoek, M.; Kotterman, M.J.J.; Dael, P. van; Firweather-Tail, S.J.

    2004-01-01

    Objective: To measure the bioavailability of selenium from cooked and raw fish in humans by estimating and comparing apparent absorption and retention of selenium in biosynthetically labelled fish with labelled selenate and biosynthetically labelled selenium in brewers yeast. Design: The

  5. Digital broadcasting

    International Nuclear Information System (INIS)

    Park, Ji Hyeong

    1999-06-01

    This book contains twelve chapters, which deals with digitization of broadcast signal such as digital open, digitization of video signal and sound signal digitization of broadcasting equipment like DTPP and digital VTR, digitization of equipment to transmit such as digital STL, digital FPU and digital SNG, digitization of transmit about digital TV transmit and radio transmit, digital broadcasting system on necessity and advantage, digital broadcasting system abroad and Korea, digital broadcasting of outline, advantage of digital TV, ripple effect of digital broadcasting and consideration of digital broadcasting, ground wave digital broadcasting of DVB-T in Europe DTV in U.S.A and ISDB-T in Japan, HDTV broadcasting, satellite broadcasting, digital TV broadcasting in Korea, digital radio broadcasting and new broadcasting service.

  6. [Digital thoracic radiology: devices, image processing, limits].

    Science.gov (United States)

    Frija, J; de Géry, S; Lallouet, F; Guermazi, A; Zagdanski, A M; De Kerviler, E

    2001-09-01

    In a first part, the different techniques of digital thoracic radiography are described. Since computed radiography with phosphore plates are the most commercialized it is more emphasized. But the other detectors are also described, as the drum coated with selenium and the direct digital radiography with selenium detectors. The other detectors are also studied in particular indirect flat panels detectors and the system with four high resolution CCD cameras. In a second step the most important image processing are discussed: the gradation curves, the unsharp mask processing, the system MUSICA, the dynamic range compression or reduction, the soustraction with dual energy. In the last part the advantages and the drawbacks of computed thoracic radiography are emphasized. The most important are the almost constant good quality of the pictures and the possibilities of image processing.

  7. Transient photoconductivity in amorphous semiconductors

    International Nuclear Information System (INIS)

    Mpawenayo, P.

    1997-07-01

    Localized states in amorphous semiconductors are divided in disorder induced shallow trap levels and dangling bonds deep states. Dangling bonds are assumed here to be either neutral or charged and their energy distribution is a single gaussian. Here, it is shown analytically that transient photocurrent in amorphous semiconductors is fully controlled by charge carriers transitions between localized states for one part and tunneling hopping carriers on the other. Localized dangling bonds deep states act as non radiative recombination centres, while hopping tunnelling is assisted by the Coulomb interaction between defects sites. The half-width of defects distribution is the disorder parameter that determines the carrier hopping time between defects sites. The macroscopic time that explains the long decay response times observed will all types of amorphous semiconductors is duly thought to be temperature dependent. Basic equations developed by Longeaud and Kleider are solved for the general case of a semiconductor after photo-generation. It turns out that the transient photoconductivity decay has two components; one with short response times from carriers trap-release transitions between shallow levels and extended states and a hopping component made of inter-dependent exponentials whose time constants span in larger ranges depending on disorder. The photoconductivity hopping component appears as an additional term to be added to photocurrents derived from existing models. The results of the present study explain and complete the power law decay derived in the multiple trapping models developed 20 years ago only in the approximation of the short response time regime. The long response time regime is described by the hopping macroscopic time. The present model is verified for all samples of amorphous semiconductors known so far. Finally, it is proposed to improved the modulated photoconductivity calculation techniques by including the long-lasting hopping dark documents

  8. Uranium incorporation into amorphous silica.

    Science.gov (United States)

    Massey, Michael S; Lezama-Pacheco, Juan S; Nelson, Joey M; Fendorf, Scott; Maher, Kate

    2014-01-01

    High concentrations of uranium are commonly observed in naturally occurring amorphous silica (including opal) deposits, suggesting that incorporation of U into amorphous silica may represent a natural attenuation mechanism and promising strategy for U remediation. However, the stability of uranium in opaline silicates, determined in part by the binding mechanism for U, is an important factor in its long-term fate. U may bind directly to the opaline silicate matrix, or to materials such as iron (hydr)oxides that are subsequently occluded within the opal. Here, we examine the coordination environment of U within opaline silica to elucidate incorporation mechanisms. Precipitates (with and without ferrihydrite inclusions) were synthesized from U-bearing sodium metasilicate solutions, buffered at pH ∼ 5.6. Natural and synthetic solids were analyzed with X-ray absorption spectroscopy and a suite of other techniques. In synthetic amorphous silica, U was coordinated by silicate in a double corner-sharing coordination geometry (Si at ∼ 3.8-3.9 Å) and a small amount of uranyl and silicate in a bidentate, mononuclear (edge-sharing) coordination (Si at ∼ 3.1-3.2 Å, U at ∼ 3.8-3.9 Å). In iron-bearing synthetic solids, U was adsorbed to iron (hydr)oxide, but the coordination environment also contained silicate in both edge-sharing and corner-sharing coordination. Uranium local coordination in synthetic solids is similar to that of natural U-bearing opals that retain U for millions of years. The stability and extent of U incorporation into opaline and amorphous silica represents a long-term repository for U that may provide an alternative strategy for remediation of U contamination.

  9. Diagnostic value of digital radiography compared to conventional screen-film system combinations

    International Nuclear Information System (INIS)

    Krug, B.; Zaehringer, M.; Lackner, K.

    1997-01-01

    Digital projection radiography provides digital data in X-ray examinations, which used to be carried out by examinations screen-film system combinations. The technological basis and clinical performances of digital luminescent radiography (DLR) and digital radiography are reviewed. Digital projection radiography does not allow to reduce selenium exposure significantly, compared to screen-film system combinations. Digital luminescent radiography can be used for the entire spectrum of analogous projection radiography the only exception being extremely subtile structural changes. The clinical experiences with digital selenium radiography achieved so far in chest X-rays are promising and the technique is expected to be increasing used in other anatomic regions as well. (orig.) [de

  10. Erythrocytic glutathione peroxidase: Its relationship to plasma selenium in man

    International Nuclear Information System (INIS)

    Perona, G.; Cellerino, R.; Guidi, G.C.; Moschini, G.; Stievano, B.M.; Tregnaghi, C.

    1977-01-01

    Erythrocytic glutathione-peroxidase (GSH-Px) activity and plasma selenium concentrations were measured in 14 patients: 7 with iron deficiency and 7 with raised serum iron levels. The decreased enzymatic activity in iron deficiency was confirmed. Plasma selenium was significantly lower in patients with lower serum iron; furthermore there is a significant correlation between serum iron and plasma selenium concentrations. Another correlation even more significant was found between plasma selenium and enzyme activity in all the cases we studied. These data suggests that the importance of iron for GSH-Px activity may be merely due to its relationship with selenium and that plasma selenium concentration may be of critical importance for enzyme activity. (author)

  11. Effect of long-term selenium supplementation on mortality

    DEFF Research Database (Denmark)

    Rayman, Margaret P.; Winther, Kristian Hillert; Pastor-Barriuso, Roberto

    2018-01-01

    concentrations higher than this are beneficial, or indeed detrimental, is unknown. Objective: In a population of relatively low selenium status, we aimed to determine the effect on mortality of long-term selenium supplementation at different dose levels. Design: The Denmark PRECISE study was a single......Background: Selenium, an essential trace element, is incorporated into selenoproteins with a wide range of health effects. Selenoproteins may reach repletion at a plasma selenium concentration of ∼ 125 μg/L, at which point the concentration of selenoprotein P reaches a plateau; whether sustained...... for extension of the study and mortality assessment. Participants were randomly assigned to treatment with 100, 200, or 300 μg selenium/d as selenium-enriched-yeast or placebo-yeast for 5 years from randomization in 1998-1999 and were followed up for mortality for a further 10 years (through March 31, 2015...

  12. Biogeochemical studies of selenium in the Indian Ocean

    International Nuclear Information System (INIS)

    Hattori, H.; Nakaguchi, Y.; Hiraki, K.; Kimura, M.; Koike, Y.

    1999-01-01

    Selenium that is a one of trace essential elements exists mainly in the chemical form of Se(IV), Se(VI) and organic selenium in ocean. Moreover, the monitoring of the selenium species has become a matter of interest as a mean of estimating their influence in biological processes in ocean. In recent works, some investigators reported that Se(IV) shows nutrient-type especially like silica's behavior, Se(VI) shows an approximately constant value, and the biological activities control the distribution of organic selenium. However, these reports were not included the whole world's oceans. It is necessary to research several oceans for the explication of fate on selenium. We investigated at the most interesting area - the Eastern Indian Ocean where should play a key role in global ocean's cycle for acquiring the new knowledge of selenium species at first

  13. Production of selenium-enriched milk and dairy products

    Directory of Open Access Journals (Sweden)

    Csapó J.

    2015-01-01

    Full Text Available Until the middle of the last century, selenium was considered to be toxic, but recently it turned out to be a micronutrient with important physiological effects, whose lack impedes the functioning of several enzymes, while in the case of a prolonged deficiency, disease processes can also occur in the body. Hungary belongs to the selenium-deficient regions in Europe; therefore, our aim was to contribute to the improvement of selenium supply of the population through increasing the selenium content of milk and dairy products. A daily supplementation of 1-6 mg organic selenium to the feed of dairy cows increases the selenium content of milk from the value of 18 μg/kg to 94 μg/kg in 8 weeks, decreasing again to the initial value in 6 weeks after stopping the supplementation.

  14. Selenium Poisoning of Wildlife and Western Agriculture: Cause and Effect

    Energy Technology Data Exchange (ETDEWEB)

    Korte, N.E.

    2000-02-01

    This project examined the hypothesis that selenium contamination is not the principal cause of the decline of endemic fish species in the Upper Colorado Basin. Activities employed to test this hypothesis included a reconnaissance of locations altered by recent road construction, a re-interpretation of available literature regarding selenium toxicity, and the interpretation of unpublished data obtained from the Upper Colorado Basin Fish Recovery Program. The project demonstrates that most of the evidence implicating selenium is circumstantial.

  15. Amorphous Silicon: Flexible Backplane and Display Application

    Science.gov (United States)

    Sarma, Kalluri R.

    Advances in the science and technology of hydrogenated amorphous silicon (a-Si:H, also referred to as a-Si) and the associated devices including thin-film transistors (TFT) during the past three decades have had a profound impact on the development and commercialization of major applications such as thin-film solar cells, digital image scanners and X-ray imagers and active matrix liquid crystal displays (AMLCDs). Particularly, during approximately the past 15 years, a-Si TFT-based flat panel AMLCDs have been a huge commercial success. a-Si TFT-LCD has enabled the note book PCs, and is now rapidly replacing the venerable CRT in the desktop monitor and home TV applications. a-Si TFT-LCD is now the dominant technology in use for applications ranging from small displays such as in mobile phones to large displays such as in home TV, as well-specialized applications such as industrial and avionics displays.

  16. The essentiality of selenium for humans, animals, and plants, and the role of selenium in plant metabolism and physiology

    Directory of Open Access Journals (Sweden)

    Garousi F.

    2017-10-01

    Full Text Available After its discovery, selenium was most noted for its harmful effects. Selenium was the first element identified to occur in native vegetation at levels toxic to animals. Poisoning of animals can occur through consumption of plants containing toxic levels of selenium. Livestock consuming excessive amounts of selenized forages are afflicted with “alkali disease” and “blind staggers”. Typical symptoms of these diseases include loss of hair, deformed hooves, blindness, colic, diarrhoea, lethargy, increased heart and respiration rates, and eventually death. On the other hand, selenium deficiency in animal feeds can cause “white muscle disease”, a degenerative disease of the cardiac and skeletal muscles. In this regard, this review paper attempts to summarize the essentiality of selenium for humans, animals, and plants and the role of selenium in plant metabolism and physiology.

  17. Effects of selenium on mallard duck reproduction and immune function

    Energy Technology Data Exchange (ETDEWEB)

    Whiteley, P.L.; Yuill, T.M.; Fairbrother, A.

    1989-11-01

    Selenium from irrigation drain water and coal-fired power stations is a significant environmental contaminant in some regions of the USA. The objectives were to examine whether selenium-exposed waterfowl had altered immune function, disease resistance, or reproduction. Pairs of adult mallards were exposed for 95-99 days on streams with sodium selenite-treated water at 10 and 30 ppb, or on untreated streams. Selenium biomagnified through the food chain to the ducks. Disease resistance was decreased in ducklings hatched on the streams and challenged with duck hepatitis virus 1 (DHV1) when 15-days old. Liver selenium concentrations for these ducklings on the 10 and 30 ppb streams was 3.6 and 7.6 ppm dry weight, respectively. Mortality of ducklings purchased when 7-days old, exposed to selenium for 14 days, and challenged when 22-days old was not affected. However, their selenium exposure was lower (liver selenium 4.1 ppm dry weight for the 30 ppb stream). Five parameters of immune function were measured in adult ducks. Phagocytosis of killed Pasteurella multocida by blood heterophils and monocytes, and blood monocyte concentrations were higher in adult males following 84 days exposure to 30 ppb selenium. Their liver selenium concentrations were 11.1 ppm dry weight after 95-99 days exposure.

  18. Brazil nuts: an effective way to improve selenium status.

    Science.gov (United States)

    Thomson, Christine D; Chisholm, Alexandra; McLachlan, Sarah K; Campbell, Jennifer M

    2008-02-01

    Brazil nuts provide a rich natural source of selenium, yet no studies have investigated the bioavailability of selenium in humans. We investigated the efficacy of Brazil nuts in increasing selenium status in comparison with selenomethionine. A randomized controlled trial was conducted with 59 New Zealand adults. Participants consumed 2 Brazil nuts thought to provide approximately 100 mug Se, 100 mug Se as selenomethionine, or placebo daily for 12 wk. Actual intake from nuts averaged 53 mug Se/d (possible range: 20-84 mug Se). Plasma selenium and plasma and whole blood glutathione peroxidase (GPx) activities were measured at baseline and at 2, 4, 8, and 12 wk, and effects of treatments were compared. Plasma selenium increased by 64.2%, 61.0%, and 7.6%; plasma GPx by 8.3%, 3.4%, and -1.2%; and whole blood GPx by 13.2%, 5.3%, and 1.9% in the Brazil nut, selenomethionine, and placebo groups, respectively. Change over time at 12 wk in plasma selenium (P nut (P nut group than in the placebo (P = 0.002) and selenomethionine (P = 0.032) groups. Consumption of 2 Brazil nuts daily is as effective for increasing selenium status and enhancing GPx activity as 100 mug Se as selenomethionine. Inclusion of this high-selenium food in the diet could avoid the need for fortification or supplements to improve the selenium status of New Zealanders.

  19. Selenium and phosphorus interaction in pea (pisum sativum L.)

    International Nuclear Information System (INIS)

    Singh, Mahendra; Bhandari, D.K.

    1975-01-01

    The interaction of selenium and phosphorus on the dry matter yield and concentration and uptake of phosphorus, sulfur and selenium was studied in pea (Pisum sativnum) var. T 163. The fertilizer was tagged with P 32 . It was observed that increased concentration of applied selenium in soil decreased the dry matter yield and increased the concentration and uptake of total P, soil P and selenium in pea plants. Increased concentration of P alone increased dry matter yield, concentration and uptake of total, soil and fertilizer P and selenium which was beyond safe limits, and decreased concentration and uptake of sulphur. Selenium and phosphorus showed strong synergetic relationship by increasing the concentration of each other in plants while both showed antagonistic effect on the concentration of sulphur. Phosphorus compensated the toxic effect of selenium and improved the growth and dry matter yield of pea plants. The highest selenium concentration of 22.4 ppm was observed in 100 ppm phosphorus with 5 ppm selenium treated pots while lowest (0.10 ppm) in control. (author)

  20. Ecological Importance of Insects in Selenium Biogenic Cycling

    Directory of Open Access Journals (Sweden)

    Nadezhda Golubkina

    2014-01-01

    Full Text Available Selenium is an essential trace element for animal and human beings. Despite the importance of insects in most ecosystems and their significant contribution to the biological cycling of trace elements due to high abundance, population productivity, and diverse ecosystem functions, surprisingly little information is available on selenium bioaccumulation by these arthropods. This review considers selenium essentiality and toxicity to insects as well as insects’ contribution to selenium trophic transfer through the food chains. Data on Se accumulation by insects of the Dniester River Valley with no anthropogenic Se loading reveal typically low Se content in necrophagous insects compared to predators and herbivores and seasonal variations in Se accumulation.

  1. Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

    KAUST Repository

    Chaieb, Sahraoui

    2015-04-09

    Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

  2. Preparation of selenium coatings onto beryllium foils

    International Nuclear Information System (INIS)

    Erikson, E.D.; Tassano, P.L.; Reiss, R.H.; Griggs, G.E.

    1984-09-01

    A technique for preparing selenium films onto 50.8 microns thick beryllium foils is described. The selenium was deposited in vacuum from a resistance heated evaporation source. Profilometry measurements of the coatings indicate deposit thicknesses of 5.5, 12.9, 37.5, 49.8 and 74.5 microns. The control of deposition rate and of coating thickness was facilitated using a commercially available closed-loop programmable thin film controller. The x-ray transmission of the coated substrates was measured using a tritiated zirconium source. The transmissivities of the film/substrate combination are presented for the range of energies from 4 to 20 keV. 15 references, 3 figures

  3. The Cultivation and SeleniumEnrichment of SeleniumEnriched Earthworm

    Directory of Open Access Journals (Sweden)

    SUN Xiao-fei

    2014-12-01

    Full Text Available As a bio-carrier, Eisenia fetida was fed with cow dung that added with sodium selenite in order to transfer inorganic selenium(Se into organic selenium. Targeting on survival rate and selenium content, the effects of five Se concentrations(0, 20, 40, 60, 80, 100 mg·kg-1 and four cultivation periods(15, 30, 45, 60 don earthworm growth and Se contents were investigated. The cultivation method with high survival rate, high Se content of earthworm and short breeding time would be screened out. The experimental results showed that the earthworm survival rate decreased and the Se content in earthworm increased with the increase of Se application and the extension of breeding time. The most optimummethod was screened out when the Se concentration was 80 mg·kg-1 and the cultivation period was 45 days, Se content in earthworm was up to 33.25 mg·kg-1.

  4. Improvement of Selenium Status of Pasture Crops

    DEFF Research Database (Denmark)

    Nielsen, Gunnar Gissel

    1984-01-01

    Selenium was applied to pasture crops in a field experiment (1) by foliar application of 10 g Se/ha as selenite in the spring, (2) or by 5 g Se/ha in the spring plus 5 g in early August, (3) as selenite-enriched calcium ammonium nitrate (CAN) at 4 g Se/ha after each cut, and (4) as 4 g Se after...

  5. Hydrogen in disordered and amorphous solids

    International Nuclear Information System (INIS)

    Bambakidis, G; Bowman, R.C.

    1986-01-01

    This book presents information on the following topoics: elements of the theory of amorphous semiconductors; electronic structure of alpha-SiH; fluctuation induced gap states in amorphous hydrogenated silicon; hydrogen on semiconductor surfaces; the influence of hydrogen on the defects and instabilities in hydrogenated amorphous silicon; deuteron magnetic resonance in some amorphous semiconductors; formation of amorphous metals by solid state reactions of hydrogen with an intermetallic compound; NMR studies of the hydrides of disordered and amorphous alloys; neutron vibrational spectroscopy of disordered metal-hydrogen system; dynamical disorder of hydrogen in LaNi /SUB 5-y/ M /SUB y/ hydrides studied by quasi-elastic neutron scattering; recent studies of intermetallic hydrides; tritium in Pd and Pd /SUB 0.80/ Sg /SUB 0.20/ ; and determination of hydrogen concentration in thin films of absorbing materials

  6. Selenium uptake and assessment of the biochemical changes in Arthrospira (Spirulina) platensis biomass during the synthesis of selenium nanoparticles.

    Science.gov (United States)

    Zinicovscaia, I; Chiriac, T; Cepoi, L; Rudi, L; Culicov, O; Frontasyeva, M; Rudic, V

    2017-01-01

    The process of selenium uptake by biomass of the cyanobacterium Arthrospira (Spirulina) platensis was investigated by neutron activation analysis at different selenium concentrations in solution and at different contact times. Experimental data showed good fit with the Freundlich adsorption isotherm model, with a regression coefficient value of 0.99. In terms of absorption dependence on time, the maximal selenium content was adsorbed in the first 5 min of interaction without significant further changes. It was also found that A. platensis biomass forms spherical selenium nanoparticles. Biochemical analysis was used to assess the changes in the main components of spirulina biomass (proteins, lipids, carbohydrates, and phycobilin) during nanoparticle formation.

  7. Impact of Selenium Supplementation on Growth and Selenium Accumulation on Spinach (Spinacia oleracea L. Plants

    Directory of Open Access Journals (Sweden)

    Azadeh SAFFARYAZDI

    2012-11-01

    Full Text Available Selenium (Se has been proved to be an essential element for humans and animals. However, less is known about its effects on plants. A hydroponic experiment was carried out to investigate the effects of selenium on growth, selenium accumulation and some physiological characteristics of spinach (Spinacia oleracea L. cv. Missouri plants. Plants were grown in Hoagland nutrient solution amended with sodium selenite at 0 (control, 1, 2, 4, 6 and 10 mg.L-1 for 28 days. Growth parameters like shoot and root fresh weight, shoot and root dry weight, total dry weight, shoot and root length increased by 17, 15, 38, 19, 18 and 34 percent in response to the lowest concentration of Se (1 mg L-1, respectively over control. However, application of higher Se concentrations reduced these parameters as compared to control. Selenium up to 1 mg L-1 enhanced the levels of chlorophyll a and chlorophyll b by 87 and 165 percent, respectively, while higher levels of Se exert toxic effects. Total phenolic compounds in leaves increased directly by increasing the level of Se and plants treated with 10 mg. L-1 Se had the highest values. Selenium, sodium and calcium content increased, while potassium content decreased, by increasing selenium treatments. The highest amounts of Se in shoots (3.89 mg g-1 DW and roots (4.27 mg g-1 DW were obtained for the highest concentration of Se (10 mg L-1. The present results suggested the beneficial effects of Se on spinach growth and also its contribute ion to improving the nutritional value of spinach for livestock and human nutrition.

  8. Selenium accumulation and metabolism in algae.

    Science.gov (United States)

    Schiavon, Michela; Ertani, Andrea; Parrasia, Sofia; Vecchia, Francesca Dalla

    2017-08-01

    Selenium (Se) is an intriguing element because it is metabolically required by a variety of organisms, but it may induce toxicity at high doses. Algae primarily absorb selenium in the form of selenate or selenite using mechanisms similar to those reported in plants. However, while Se is needed by several species of microalgae, the essentiality of this element for plants has not been established yet. The study of Se uptake and accumulation strategies in micro- and macro-algae is of pivotal importance, as they represent potential vectors for Se movement in aquatic environments and Se at high levels may affect their growth causing a reduction in primary production. Some microalgae exhibit the capacity of efficiently converting Se to less harmful volatile compounds as a strategy to cope with Se toxicity. Therefore, they play a crucial role in Se-cycling through the ecosystem. On the other side, micro- or macro-algae enriched in Se may be used in Se biofortification programs aimed to improve Se content in human diet via supplementation of valuable food. Indeed, some organic forms of selenium (selenomethionine and methylselenocysteine) are known to act as anticarcinogenic compounds and exert a broad spectrum of beneficial effects in humans and other mammals. Here, we want to give an overview of the developments in the current understanding of Se uptake, accumulation and metabolism in algae, discussing potential ecotoxicological implications and nutritional aspects. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Krypton ion implantation effect on selenium nanowires

    Science.gov (United States)

    Panchal, Suresh; Chauhan, R. P.

    2017-08-01

    Among the rapidly progressing interdisciplinary areas of physics, chemistry, material science etc. ion induced modifications of materials is one such evolving field. It has been realized in recent years that a material, in the form of an accelerated ion beam, embedded into a target specimen offers a most productive tool for transforming its properties in a controlled manner. In semiconductors particularly, where the transport behavior is determined by very small concentrations of certain impurities, implantation of ions may bring considerable changes. The present work is based on the study of the effect of krypton ion implantation on selenium nanowires. Selenium nanowires of diameter 80 nm were synthesized by template assisted electro deposition technique. Implantation of krypton ions was done at Inter University Accelerator Centre (IUAC), New Delhi, India. The effect of implantation on structural, electrical and optical properties of selenium nanowires was investigated. XRD analysis of pristine and implanted nanowires shows no shifting in the peak position but there is a variation in the relative intensity with fluence. UV-Visible spectroscopy shows the decrease in the optical band gap with fluence. PL spectra showed emission peak at higher wavelength. A substantial rise in the current was observed from I-V measurements, after implantation and with the increase in fluence. The increase in current conduction may be due to the increase in the current carriers.

  10. The physics and applications of amorphous semiconductors

    CERN Document Server

    Madan, Arun

    1988-01-01

    This comprehensive, detailed treatise on the physics and applications of the new emerging technology of amorphous semiconductors focuses on specific device research problems such as the optimization of device performance. The first part of the book presents hydrogenated amorphous silicon type alloys, whose applications include inexpensive solar cells, thin film transistors, image scanners, electrophotography, optical recording and gas sensors. The second part of the book discusses amorphous chalcogenides, whose applications include electrophotography, switching, and memory elements. This boo

  11. Polyamorphous transition in amorphous fullerites C70

    International Nuclear Information System (INIS)

    Borisova, P. A.; Agafonov, S. S.; Glazkov, V. P.; D’yakonova, N. P.; Somenkov, V. A.

    2011-01-01

    Samples of amorphous fullerites C 70 have been obtained by mechanical activation (grinding in a ball mill). The structure of the samples has been investigated by neutron and X-ray diffraction. The high-temperature (up to 1200°C) annealing of amorphous fullerites revealed a polyamorphous transition from molecular to atomic glass, which is accompanied by the disappearance of fullerene halos at small scattering angles. Possible structural versions of the high-temperature amorphous phase are discussed.

  12. Amorphous silicon based radiation detectors

    International Nuclear Information System (INIS)

    Perez-Mendez, V.; Cho, G.; Drewery, J.; Jing, T.; Kaplan, S.N.; Qureshi, S.; Wildermuth, D.; Fujieda, I.; Street, R.A.

    1991-07-01

    We describe the characteristics of thin(1 μm) and thick (>30μm) hydrogenated amorphous silicon p-i-n diodes which are optimized for detecting and recording the spatial distribution of charged particles, x-rays and γ rays. For x-ray, γ ray, and charged particle detection we can use thin p-i-n photosensitive diode arrays coupled to evaporated layers of suitable scintillators. For direct detection of charged particles with high resistance to radiation damage, we use the thick p-i-n diode arrays. 13 refs., 7 figs

  13. The effect of image processing on the detection of cancers in digital mammography.

    Science.gov (United States)

    Warren, Lucy M; Given-Wilson, Rosalind M; Wallis, Matthew G; Cooke, Julie; Halling-Brown, Mark D; Mackenzie, Alistair; Chakraborty, Dev P; Bosmans, Hilde; Dance, David R; Young, Kenneth C

    2014-08-01

    OBJECTIVE. The objective of our study was to investigate the effect of image processing on the detection of cancers in digital mammography images. MATERIALS AND METHODS. Two hundred seventy pairs of breast images (both breasts, one view) were collected from eight systems using Hologic amorphous selenium detectors: 80 image pairs showed breasts containing subtle malignant masses; 30 image pairs, biopsy-proven benign lesions; 80 image pairs, simulated calcification clusters; and 80 image pairs, no cancer (normal). The 270 image pairs were processed with three types of image processing: standard (full enhancement), low contrast (intermediate enhancement), and pseudo-film-screen (no enhancement). Seven experienced observers inspected the images, locating and rating regions they suspected to be cancer for likelihood of malignancy. The results were analyzed using a jackknife-alternative free-response receiver operating characteristic (JAFROC) analysis. RESULTS. The detection of calcification clusters was significantly affected by the type of image processing: The JAFROC figure of merit (FOM) decreased from 0.65 with standard image processing to 0.63 with low-contrast image processing (p = 0.04) and from 0.65 with standard image processing to 0.61 with film-screen image processing (p = 0.0005). The detection of noncalcification cancers was not significantly different among the image-processing types investigated (p > 0.40). CONCLUSION. These results suggest that image processing has a significant impact on the detection of calcification clusters in digital mammography. For the three image-processing versions and the system investigated, standard image processing was optimal for the detection of calcification clusters. The effect on cancer detection should be considered when selecting the type of image processing in the future.

  14. Studies of hydrogenated amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, S G; Carlos, W E

    1984-07-01

    This report discusses the results of probing the defect structure and bonding of hydrogenated amorphous silicon films using both nuclear magnetic resonance (NMR) and electron spin resonance (ESR). The doping efficiency of boron in a-Si:H was found to be less than 1%, with 90% of the boron in a threefold coordinated state. On the other hand, phosphorus NMR chemical shift measurements yielded a ration of threefold to fourfold P sites of roughly 4 to 1. Various resonance lines were observed in heavily boron- and phosphorus-doped films and a-SiC:H alloys. These lines were attributed to band tail states on twofold coordinated silicon. In a-SiC:H films, a strong resonance was attributed to dangling bonds on carbon atoms. ESR measurements on low-pressure chemical-vapor-deposited (LPCVD) a-Si:H were performed on samples. The defect density in the bulk of the films was 10/sup 17//cc with a factor of 3 increase at the surface of the sample. The ESR spectrum of LPCVD-prepared films was not affected by prolonged exposure to strong light. Microcrystalline silicon samples were also examined. The phosphorus-doped films showed a strong signal from the crystalline material and no resonance from the amorphous matrix. This shows that phosphorus is incorporated in the crystals and is active as a dopant. No signal was recorded from the boron-doped films.

  15. Low blood selenium: A probable factor in essential hypertension ...

    African Journals Online (AJOL)

    Blood selenium (BSe) and plasma glutathione peroxidase (plGSH-Px) activity were measured as biochemical markers of selenium status of 103 hypertensive patients (44 males and 59 females) and 88 apparently healthy subjects (40 males and 48 females). The hypertensive patients were classified into three groups based ...

  16. The selenium status of grazing herbivores in different regions of ...

    African Journals Online (AJOL)

    Unknown

    The selenium status of grazing herbivores in different regions of Southern Africa. J. B. J. van Ryssen. Dept of Animal and Wildlife Sciences, University of Pretoria, 0002 Pretoria, South Africa. E-mail:jvryssen@postino.up.ac.za. Although a substantial amount of information is available on the selenium status of grazing animals ...

  17. Molecular neutron activation analysis of selenium metabolites in urine

    International Nuclear Information System (INIS)

    Blotcky, A.J.; Hansen, G.T.; Ebrahim, A.; Rack, E.P.

    1988-01-01

    Because of the biological importance of selenium in living biological systems, various analytical procedures have been developed for analysis of microquantities of elemental selenium, in urine, serum, and tissue. For urine selenium, these include atomic absorption spectrometry, solution absorption spectrometry, solution fluorescence spectrometry, volumetry, and neutron activation analysis. Of equal or greater importance is the determination of selenium metabolites present in urine for the purpose of describing the biological pathways for the metabolism of selenium in living organisms. While it is known from previous studies that trimethylselenonium ion (TMSe) is a major metabolite in urine, probably the result of reduction and methylation reaction, there are no definitive results in the literature indicating the nature or quantity of other selenium metabolic products in urine. Early techniques to measure TMSe levels in urine involved the use of the radiotracer 75 Se. Because of the long biological half-life of selenium and issues of radiation exposure, its use in humans has been limited. In this paper, the authors report the experimental procedure for the determination of total selenoamino acid concentration in urine and present total selenium values, and, where applicable, TMSe, SeO 2- 3 , and total selenoamino acid concentrations in the urine of normal and diseased subjects

  18. Relationship between soil contents and plasma levels of selenium ...

    African Journals Online (AJOL)

    The soil contents of trace elements selenium, chromium and manganese were measured to determine their impact on the plasma levels of 160 healthy adult Nigerians in five different experimental locations in Cross River and Akwa Ibom States, South - South Nigeria. The mean (±SD) soil selenium, chromium and ...

  19. Effects of Selenium Yeast on Blood Glucose and Antioxidant ...

    African Journals Online (AJOL)

    olayemitoyin

    Summary: Selenium is an antioxidant that prevents oxygen radical from damaging cells from chronic diseases that can develop from cell injury and inflammation such as diabetes mellitus. The aim of the study is to investigate the possible protective effect of selenium yeast on cholesterol diet induced type-2 diabetes mellitus ...

  20. Aquatic selenium pollution is a global environmental safety issue

    Science.gov (United States)

    A. Dennis Lemly

    2004-01-01

    Selenium pollution is a worldwide phenomenon and is associated with a broad spectrum of human activities, ranging from the most basic agricultural practices to the most high-tech industrial processes. Consequently, selenium contamination of aquatic habitats can take place in urban, suburban, and rural settings alike--from mountains to plains, from deserts to...

  1. Mercury and selenium in wild and experimental seals

    NARCIS (Netherlands)

    Ven, van de W.S.M.; Koeman, J.H.; Svenson, A.

    1979-01-01

    This paper describes the tissue distribution of inorganic mercury, organic mercury selenium in Dutch and British seals as well as in seals which were dosed with methylmercury under experimental conditions. In the experimental animals, a time-related increase of both mercury and selenium was found in

  2. Electrical and switching properties of InSe amorphous thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kenawy, M.A.; Zayed, H.A.; El-Zahid, H.A. (Univ. Coll. for Girls, Ain Shams Univ., Cairo (Egypt)); El-Shazly, A.F.; Afifi, M.A. (Faculty of Education, Ain Shams Univ., Cairo (Egypt))

    1991-05-15

    In this work electrical and switching properties of InSe thin films have been studied. The semiconductor compound InSe was obtained by direct synthesis from stoichiometric amounts of spectroscopically pure indium and selenium. By slow cooling of the synthesized InSe a polycrystalline material is obtained. The amorphous films were obtained by thermal evaporation under vacuum of the polycrystalline material on glass or pyrographite substrates. From electrical measurements, it was found that for all films the dark electrical resistivity decreases with an increase in film thickness and temperature. The InSe compound exhibits non-linear I-V characteristics and switching phenomena. The threshold voltage decreases with increasing annealing temperature and increases with increasing film thickness. (orig.).

  3. Higher selenium status is associated with adverse blood lipid profile in British adults

    Science.gov (United States)

    Recent findings have raised concern about possible associations of high selenium exposure with diabetes and hyperlipidemia in the US, a population with high selenium status. In the UK, a population with lower selenium status, there is little data on the association of selenium status with cardio-met...

  4. ACCUMULATION OF SELENIUM IN AQUATIC ORGANISMS OF THE CASPIAN SEA

    Directory of Open Access Journals (Sweden)

    N. A. Golubkina

    2012-01-01

    Full Text Available The question of establishing the levels of selenium accumulation in fish Marine has consistently attracted the attention of researchers. This is due, no doubt, with a surprisingly high concentrations of trace elements in fishmuscle mass compared with terrestrial animals and the wide spread lack of public consumption of selenium in most countries of the world. By the ability to accumulate selenium species investigated can be arranged in series: carp < rudd < pike Kutum < perch < carp < mullet < silverside < pike < roach < sprat common < gobies < sprat anchovy << sturgeon. It is known that the main source of selenium to fish is the food, although there is some element passes through the gills during respiration. Comparing the results with data accumulation of selenium muscle tissue of fish from different regions of the world indicates the absence of express selenodefitsita in the Caspian Sea.

  5. Is selenium supplementation in autoimmune thyroid diseases justified?

    DEFF Research Database (Denmark)

    Winther, Kristian H.; Bonnema, Steen; Hegedüs, Laszlo

    2017-01-01

    PURPOSE OF REVIEW: This review provides an appraisal of recent evidence for or against selenium supplementation in patients with autoimmune thyroid diseases, and discusses possible effect mechanisms. RECENT FINDINGS: Epidemiological data suggest an increased prevalence of autoimmune thyroid...... diseases under conditions of low dietary selenium intake. Two systematic reviews have evaluated controlled trials among patients with autoimmune thyroiditis and report that selenium supplementation decreases circulating thyroid autoantibodies. The immunomodulatory effects of selenium might involve reducing...... supplementation in the standard treatment of patients with autoimmune thyroiditis or Graves’ disease. However, correction of moderate to severe selenium deficiency may offer benefits in preventing, as well as treating, these disorders. Molecular mechanisms have been proposed, but further studies are needed....

  6. Recent Microextraction Techniques for Determination and Chemical Speciation of Selenium

    Directory of Open Access Journals (Sweden)

    Ibrahim Ahmed S. A.

    2017-05-01

    Full Text Available Research designed to improve extraction has led to the development of microextraction techniques (ME, which involve simple, low cost, and effective preconcentrationof analytes in various matrices. This review is concerned with the principles and theoretical background of ME, as well as the development of applications for selenium analysis during the period from 2008 to 2016. Among all ME, dispersive liquid-liquid microextraction was found to be most favorable for selenium. On the other hand, atomic absorption spectrometry was the most frequently used instrumentation. Selenium ME have rarely been coupled to spectrophotometry and X-ray spectrophotometry methods, and there is no published application of ME with electrochemical techniques. We strongly support the idea of using a double preconcentration process, which consists of microextraction prior to preconcentration, followed by selenium determination using cathodic stripping voltammetry (ME-CSV. More attention should focus on the development of accurate, precise, and green methods for selenium analysis.

  7. Level of selenium intake the region of algiers ration

    International Nuclear Information System (INIS)

    Benamar, M.A.; Tahtat, D.; Aklil, K.; Azbouche, A.; Mozai, M.

    2001-01-01

    In this present work, we have measured the selenium content in different food frequently consumed in the region of Algiers, a nutritional deficiency in selenium may be a risk factor for cardiovascular diseases, the function mainly as a protection agent against the toxic effects of free radicals, selenium are related to its presence at the active site of the enzyme glutathion peroxidase. Freeze-dried samples of food were put in cell and measured by INAA (Instrumental Neutron Activation Analysis). We have established the annual consumption of selenium for five socio-professional categories (private employers, high commissioned officers, medium commissioned officers, workers, maneuvers ), on the basis of data given by government agencies. We have determined as mean daily consumption of selenium by people in region of Algiers was 130 ug per day

  8. Selenium content in wheat and estimation of the selenium daily intake in different regions of Algeria

    International Nuclear Information System (INIS)

    Beladel, B.; Nedjimi, B.; Mansouri, A.; Tahtat, D.; Belamri, M.; Tchanchane, A.; Khelfaoui, F.; Benamar, M.E.A.

    2013-01-01

    In this work, we have measured the selenium content in wheat produced locally in eight different regions of Algeria from east to west, and we have established the annual consumption of selenium for five socio-professional categories. Instrumental neutron activation analysis is used. The selenium levels in wheat samples varied from 21 (Tiaret) to 153 μg/kg (Khroub), with a mean value about 52 μg/kg. The mean of selenium daily consumption from ingestion of wheat per person in the eight regions varied from 32 to 52 μg/day which is close to the minimal FAO recommendation. - Highlights: ► Cereals and cereal products represent a staple food in Algeria. ► The objective of this study is to determine the Se intake in wheat produced locally. ► The concentration of Se in the wheat reflects the level of the Se in regional soils. ► The mean of Se daily consumption is close to the minimal WHO/FAO recommendation.

  9. Structural morphology of amorphous conducting carbon film

    Indian Academy of Sciences (India)

    Unknown

    in nanotubes and sp3 rich amorphous carbons for their application in field emission, device application, etc in- vestigations on sp2 rich amorphous carbon forms are very few. Though DLC films have potential application in field emission (FE) due to their low threshold voltage, the carbon centres, which are believed to play ...

  10. Towards upconversion for amorphous silicon solar cells

    NARCIS (Netherlands)

    de Wild, J.; Meijerink, A.; Rath, J.K.; van Sark, W.G.J.H.M.; Schropp, R.E.I.

    2010-01-01

    Upconversion of subbandgap light of thin film single junction amorphous silicon solar cells may enhance their performance in the near infrared (NIR). In this paper we report on the application of the NIR–vis upconverter β-NaYF4:Yb3+(18%) Er3+(2%) at the back of an amorphous silicon solar cell in

  11. Film adhesion in amorphous silicon solar cells

    Indian Academy of Sciences (India)

    TECS

    flexible triple junction, amorphous silicon solar cells. At the Malaysia Energy Centre (MEC), we fabricated triple junction amorphous silicon solar cells (up to 12⋅7% efficiency (Wang et al 2002)) and laser-interconnected modules on steel, glass and polyimide substrates. A major issue encountered is the adhesion of thin film ...

  12. Colors and the evolution of amorphous galaxies

    International Nuclear Information System (INIS)

    Gallagher, J.S. III; Hunter, D.A.

    1987-01-01

    UBVRI and H-alpha photometric observations are presented for 16 amorphous galaxies and a comparison sample of Magellanic irregular (Im) and Sc spiral galaxies. These data are analyzed in terms of star-formation rates and histories in amorphous galaxies. Amorphous galaxies have mean global colors and star-formation rates per unit area that are similar to those in giant Im systems, despite differences in spatial distributions of star-forming centers in these two galactic structural classes. Amorphous galaxies differ from giant Im systems in having somewhat wider scatter in relationships between B - V and U - B colors, and between U - B and L(H-alpha)/L(B). This scatter is interpreted as resulting from rapid variations in star-formation rates during the recent past, which could be a natural consequence of the concentration of star-forming activity into centrally located, supergiant young stellar complexes in many amorphous galaxies. While the unusual spatial distribution and intensity of star formation in some amorphous galaxies is due to interactions with other galaxies, several amorphous galaxies are relatively isolated and thus the processes must be internal. The ultimate evolutionary fate of rapidly evolving amorphous galaxies remains unknown. 77 references

  13. Amorphization of ice under mechanical stresses

    Science.gov (United States)

    Bordonskii, G. S.; Krylov, S. D.

    2017-11-01

    The dielectric parameters of freshly produced freshwater ice in the microwave range are investigated. It is established that this kind of ice contains a noticeable amount of amorphous ice. Its production is associated with plastic deformation under mechanical stresses. An assessment of the dielectric-permeability change caused by amorphous ice in the state of a slowly flowing medium is given.

  14. Electron beam recrystallization of amorphous semiconductor materials

    Science.gov (United States)

    Evans, J. C., Jr.

    1968-01-01

    Nucleation and growth of crystalline films of silicon, germanium, and cadmium sulfide on substrates of plastic and glass were investigated. Amorphous films of germanium, silicon, and cadmium sulfide on amorphous substrates of glass and plastic were converted to the crystalline condition by electron bombardment.

  15. Photoexcitation-induced processes in amorphous semiconductors

    International Nuclear Information System (INIS)

    Singh, Jai

    2005-01-01

    Theories for the mechanism of photo-induced processes of photodarkening (PD), volume expansion (VE) in amorphous chalcogenides are presented. Rates of spontaneous emission of photons by radiative recombination of excitons in amorphous semiconductors are also calculated and applied to study the excitonic photoluminescence in a-Si:H. Results are compared with previous theories

  16. Analytical theory of noncollinear amorphous metallic magnetism

    International Nuclear Information System (INIS)

    Kakehashi, Y.; Uchida, T.

    2001-01-01

    Analytical theory of noncollinear magnetism in amorphous metals is proposed on the basis of the Gaussian model for the distribution of the interatomic distance and the saddle-point approximation. The theory removes the numerical difficulty in the previous theory based on the Monte-Carlo sampling method, and reasonably describes the magnetic properties of amorphous transition metals

  17. Solid-state diffusion in amorphous zirconolite

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.; Dove, M. T.; Trachenko, K. [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Zarkadoula, E. [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6138 (United States); Todorov, I. T. [STFC Daresbury Laboratory, Warrington WA4 1EP (United Kingdom); Geisler, T. [Steinmann-Institut für Geologie, Mineralogie und Paläontologie, University of Bonn, D-53115 Bonn (Germany); Brazhkin, V. V. [Institute for High Pressure Physics, RAS, 142190 Moscow (Russian Federation)

    2014-11-14

    We discuss how structural disorder and amorphization affect solid-state diffusion, and consider zirconolite as a currently important case study. By performing extensive molecular dynamics simulations, we disentangle the effects of amorphization and density, and show that a profound increase of solid-state diffusion takes place as a result of amorphization. Importantly, this can take place at the same density as in the crystal, representing an interesting general insight regarding solid-state diffusion. We find that decreasing the density in the amorphous system increases pre-factors of diffusion constants, but does not change the activation energy in the density range considered. We also find that atomic species in zirconolite are affected differently by amorphization and density change. Our microscopic insights are relevant for understanding how solid-state diffusion changes due to disorder and for building predictive models of operation of materials to be used to encapsulate nuclear waste.

  18. Locomotion of Amorphous Surface Robots

    Science.gov (United States)

    Bradley, Arthur T. (Inventor)

    2016-01-01

    An amorphous robot includes a compartmented bladder containing fluid, a valve assembly, and an outer layer encapsulating the bladder and valve assembly. The valve assembly draws fluid from a compartment(s) and discharges the drawn fluid into a designated compartment to displace the designated compartment with respect to the surface. Another embodiment includes elements each having a variable property, an outer layer that encapsulates the elements, and a control unit. The control unit energizes a designated element to change its variable property, thereby moving the designated element. The elements may be electromagnetic spheres with a variable polarity or shape memory polymers with changing shape and/or size. Yet another embodiment includes an elongated flexible tube filled with ferrofluid, a moveable electromagnet, an actuator, and a control unit. The control unit energizes the electromagnet and moves the electromagnet via the actuator to magnetize the ferrofluid and lengthen the flexible tube.

  19. Iodine and selenium migration through argillaceous rocks

    International Nuclear Information System (INIS)

    Frasca, Benjamin

    2011-01-01

    Deep argillaceous formations are considered as potential host rock for high-level radioactive waste repository. Based on safety assessment calculations, active selenium ( 79 Se) and iodine ( 129 I) from high level radioactive waste might be ones of the major dose contributors due to their longevity and their anionic character. However, because of their high sensitivity to redox condition, a special attention to the oxidation state of these elements is required. A comparative study on the diffusion properties of selenium and iodine through argillaceous rocks was realized with the aim to determine the effects of both the redox conditions and the mineralogy on the migration of these two elements. For these purposes, we have studied two argillaceous rocks: Toarcian argillite from Tournemire (France) and Opalinus clay (OPA) from the Mont-Terri (Switzerland). The study of the iodide migration allowed to confirm the control on the iodide retention of both oxidized pyrite and natural organic matter. A kinetic control of the iodide sorption is also suspected. We focus the selenium study on the more oxidized species, Se(IV) and Se(VI). The Se(IV) migration is strongly dependant from oxido-reduction processes. Indeed, the Se(IV) diffusion experiments through Tournemire argillite and OPA indicated a significant reduction associated to Fe(II). The Se(VI) study evidenced a behavior dependant from the initial concentration: at the highest concentration, no significant retention was observed while the retention is significant at the lowest concentration. Furthermore, spectroscopic analyses tend to show a low Se(VI) reduction at the Fe contact. However, biotic origin cannot be excluded. (author)

  20. SELENIUM SUBSTITUTION – EFFECT ON THYROID FUNCTION

    Directory of Open Access Journals (Sweden)

    Milica Pešić

    2015-03-01

    Full Text Available The understanding of the essential role of selenium (Se in thyroid hormone synthesis, metabolism and action, as well as normal thyroid function, increased during the past decades. The thyroid gland is among the human tissues with the highest Se content per mas unit, similar to other endocrine organs and brain. Biological actions of Se are mediated, in most cases, through the expression of at least 30 selenoproteins coded by 25 selenoprotein genes in the human. Via the selenoproteins, selenium can influence the cell function through antioxidant activites, modifying redox status and thyroid hormone synthesis and metabolism. Selenoproteins iodothyronine deiodinases are present in most tissues and have a role to increase the production of bioactive tri-iodothyronine. Futhermore, Se has been shown to be important in the regulation of immune function. Se deficiency is accompained by the loss of immune competence. The links between Se deficiency, altered immune function and inflamation have prompted studies in humans to examine if Se suplementation can modify auto-antibodies production in patients with chronic autoimmune thyroiditis. Until now, several randomised prospective clinical trials have been performed in patients with established chronic autoimmune thyrioditis. The clinical endpoint of each study was the decrease in TPO antibodies concentration after 3-12 months of treatment. Ussualy, the dosage of daily Se supplementation was 200µg. Selenium suplemetation had no significant effect on the concentration of TSH or thyroid hormone concentrations. These studies indicate that Se treatment result in reduced inflammatory activity, but it does not cure chronc autoimmune process.

  1. Normal mode calculations of trigonal selenium

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; McMurry, H. L.

    1980-01-01

    The phonon dispersion relations for trigonal selenium have been calculated on the basis of a short range potential field model. Electrostatic long range forces have not been included. The force field is defined in terms of symmetrized coordinates which reflect partly the symmetry of the space group....... With such coordinates a potential energy, calculated with only a diagonal force matrix, is equivalent to one calculated with both off diagonal and diagonal elements when conventional coordinates are used. Another advantage is that often some force constants may be determined directly from frequencies at points of high...

  2. Serum selenium level and risk of lung cancer mortality

    DEFF Research Database (Denmark)

    Suadicani, P; Hein, H O; Gyntelberg, F

    2011-01-01

    Serum selenium has been implicated as a risk factor for lung cancer, but the issue remains unsettled. We tested in a cohort of 3,333 males aged 53 to 74 years the hypothesis that a low serum selenium would be associated with an increased risk of lung cancer mortality.During 16 years, 167 subjects(5.......1%) died from lung cancer; 48 males (5.0%) among males with low serum selenium, 0.4-1.0 μmol·l(-1), n=965, 57 males (5.1%) among males with medium serum selenium, 1.1-1.2 μmol·l(-1), n=1,141, and 62 males (5.1%) among males with high serum selenium, 1.3-3.0 μmol·l(-1), n=1,227. After adjustment for age...... (chronic bronchitis and peak flow), referencing the lowest level of serum selenium HRs were 1.17(0.79-1.75), and 1.43(0.96-2.14), respectively. Among heavy smokers a high serum selenium was associated with a significantly increased risk of lung cancer mortality after taking into account all potential...

  3. Selenium Nanoparticles for Stress-Resilient Fish and Livestock

    Science.gov (United States)

    Sarkar, Biplab; Bhattacharjee, Surajit; Daware, Akshay; Tribedi, Prosun; Krishnani, K. K.; Minhas, P. S.

    2015-09-01

    The fisheries and livestock sectors capture the highest share of protein-rich animal food and demonstrate accelerated growth as an agriculture subsidiary. Environmental pollution, climate change, as well as pathogenic invasions exert increasing stress impacts that lead the productivity momentum at a crossroads. Oxidative stress is the most common form of stress phenomenon responsible for the retardation of productivity in fisheries and livestock. Essential micronutrients play a determinant role in combating oxidative stress. Selenium, one of the essential micronutrients, appears as a potent antioxidant with reduced toxicity in its nanoscale form. In the present review, different methods of synthesis and characterization of nanoscale selenium have been discussed. The functional characterization of nano-selenium in terms of its effect on growth patterns, feed digestibility, and reproductive system has been discussed to elucidate the mechanism of action. Moreover, its anti-carcinogenic and antioxidant potentiality, antimicrobial and immunomodulatory efficacy, and fatty acid reduction in liver have been deciphered as the new phenomena of nano-selenium application. Biologically synthesized nano-selenium raises hope for pharmacologically enriched, naturally stable nanoscale selenium with high ecological viability. Hence, nano-selenium can be administered with commercial feeds for improvising stress resilience and productivity of fish and livestock.

  4. COMPARISON OF DETERMINING METHODS REGARDING SELENIUM CONTENT IN WHEAT PLANT

    Directory of Open Access Journals (Sweden)

    Mihaela Monica Stanciu-Burileanu

    2010-01-01

    Full Text Available As a metallic chemical element, selenium has received special attention from biologists because of its dual role as a trace element essential and toxic. The important part of enzymes that protect cells against the effects of free radicals that are produced during normal metabolism of oxygen. Also, selenium is essential for normal immune system and thyroid gland, The concentration of selenium in the soil, which varies by region, determines the default concentration of selenium in plants growing in the soil.The purpose of this paper is to present methods of comparison, dry oxidation at 450ºC and wet digestion – digestion with acids in high concentrations at microwave system digestion, for determining selenium content from wheat samples collected from the south-eastern part of Romania, namely Bărăgan Plain and Central-South Dobrogea. Selenium separation and dosage from obtained extracts carry out through a selective hydride generation atomic absorption spectrophotometry. With the software SURFER, a tendency map of selenium distribution was drawn.

  5. Selenium reverses Pteridium aquilinum-induced immunotoxic effects.

    Science.gov (United States)

    Latorre, A O; Caniceiro, B D; Wysocki, H L; Haraguchi, M; Gardner, D R; Górniak, S L

    2011-02-01

    We have previously shown that bracken fern (Pteridium aquilinum) has immunomodulatory effects on mouse natural killer (NK) cells by reducing cytotoxicity. Alternatively, it has been demonstrated that selenium can enhance NK cell activity. Therefore, the aims of the present study were to evaluate if ptaquiloside, the main toxic component found in P. aquilinum, is responsible for the immunotoxic effects observed in mice, and if selenium supplementation could prevent or even reverse these effects. Male C57BL/6 mice were administered the P. aquilinum extract by daily gavage for 30 days, and histological analyses revealed a significant reduction in splenic white pulp area that was fully reversed by selenium treatment. In addition, mice administered ptaquiloside by daily gavage for 14 days demonstrated the same reduction of NK cell activity as the P. aquilinum extract, and this reduction was prevented by selenium co-administration. Lastly, non-adherent splenic cells treated in vitro with an RPMI extract of P. aquilinum also showed diminished NK cell activity that was not only prevented by selenium co-treatment but also fully reversed by selenium post-treatment. The results of this study clearly show that the immunosuppressive effects of P. aquilinum are induced by ptaquiloside and that selenium supplementation can prevent as well as reverse these effects. Copyright © 2010 Elsevier Ltd. All rights reserved.

  6. Serum Selenium and Ceruloplasmin in Nigerians with Peripartum Cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Kamilu M. Karaye

    2015-04-01

    Full Text Available The study aimed to determine if selenium deficiency, serum ceruloplasmin and traditional birth practices are risk factors for peripartum cardiomyopathy (PPCM, in Kano, Nigeria. This is a case-control study carried out in three hospitals, and PPCM patients were followed up for six months. Critically low serum selenium concentration was defined as <70 µg/L. A total of 39 PPCM patients and 50 controls were consecutively recruited after satisfying the inclusion criteria. Mean serum selenium in patients (61.7 ± 14.9 µg/L was significantly lower than in controls (118.4 ± 45.6 µg/L (p < 0.001. The prevalence of serum selenium <70 µg/L was significantly higher among patients (76.9% than controls (22.0% (p < 0.001. The mean ceruloplasmin and prevalence of socio-economic indices, multiparity, pregnancy-induced hypertension, obesity and twin pregnancy were not different between the groups (p > 0.05. Logistic regression showed that rural residency significantly increased the odds for serum selenium <70 µg/L by 2.773-fold (p = 0.037. Baseline serum levels of selenium and ceruloplasmin were not associated with six-month mortality. This study has shown that selenium deficiency is a risk factor for PPCM in Kano, Nigeria, and is related to rural residency. However, serum ceruloplasmin, customary birth practices and some other characteristics were not associated with PPCM in the study area.

  7. Speciation of selenium in groundwater: Seasonal variations and redox transformations

    International Nuclear Information System (INIS)

    Kumar, A. Ramesh; Riyazuddin, P.

    2011-01-01

    Highlights: → Selenium(VI) was the predominant species of Se present in groundwater. → Groundwater recharge increased Se mobilization. → Dissolved oxygen and redox potential control the mobilization of soil selenium. → Shallow groundwater is susceptible for more selenium enrichment than deeper ones. - Abstract: Speciation of selenium in groundwater is essential from the viewpoint of toxicity to organisms and biogeochemical cycling. Selenium speciation in groundwater is controlled by aquifer redox conditions, microbial transformations, dissolved oxygen (DO) and other redox couples. A suburban area of Chennai city in India, where improper waste disposal measures have been practiced is selected for this study. Se(IV), Se(VI) and other hydrochemical parameters were monitored in shallow ground water during pre- and post-monsoon seasons for a period of three years. The objective of the study was to investigate the effect of groundwater recharge on selenium speciation. The concentration of Se(IV), and Se(VI) ranged between 0.15-0.43 μg L -1 and 0.16-4.73 μg L -1 , respectively. During post-monsoon period the concentration of Se(IV), and Se(VI) ranged between 0.15-1.25 μg L -1 and 0.58-10.37 μg L -1 , respectively. Se(VI) was the dominant species of selenium during the pre- and post-monsoon periods. During the post-monsoon periods, leaching of selenium from soil was more effective due to the increased oxidizing nature of the groundwater as indicated by the DO and redox potential (Eh) measurements. This finding has important implications on the behavior of selenium in groundwater, and also on the health of people consuming groundwater from seleniferous areas.

  8. Biogenesis of Selenium Nanoparticles Using Green Chemistry.

    Science.gov (United States)

    Shoeibi, Sara; Mozdziak, Paul; Golkar-Narenji, Afsaneh

    2017-11-09

    Selenium binds some enzymes such as glutathione peroxidase and thioredoxin reductase, which may be activated in biological infections and oxidative stress. Chemical and physical methods for synthesizing nanoparticles, apart from being expensive, have their own particular risks. However, nanoparticle synthesis through green chemistry is a safe procedure that different biological sources such as bacteria, fungi, yeasts, algae and plants can be the catalyst bed for processing. Synthesis of selenium nanoparticles (SeNPs) by macro/microorganisms causes variation in morphology and shape of the particles is due to diversity of reduction enzymes in organisms. Reducing enzymes of microorganisms by changing the status of redox convert metal ions (Se 2- ) to SeNPs without charge (Se 0 ). Biological activity of SeNPs includes their protective role against DNA oxidation. Because of the biological and industrial properties, SeNPs have wide applications in the fields of medicine, microelectronic, agriculture and animal husbandry. SeNPs can show strong antimicrobial effects on the growth and proliferation of microorganisms in a dose-dependent manner. The objective of this review is to consider SeNPs applications to various organisms.

  9. Selenium toxicosis in wild aquatic birds

    Science.gov (United States)

    Ohlendorf, H.M.; Kilness, A.W.; Simmons, J.L.; Stroud, R.K.; Hoffman, D.J.; Moore, John F.

    1988-01-01

    Severe gross and microscopic lesions and other changes were found in adult aquatic birds and in embryos from Kesterson Reservoir (a portion of Kesterson National Wildlife Refuge), Merced County, Calif., during 1984. Adult birds from that area were emaciated, had subacute to extensive chronic hepatic lesions, and had excess fluid and fibrin in the peritoneal cavity. Biochemical changes in their livers included elevated glycogen and non-protein-bound sulfhydryl concentrations and glutathione peroxidase activity but lowered protein, total sulfhydryl, and protein-bound sulfhydryl concentrations. Congenital malformations observed grossly in embryos were often multiple and included anophthalmia, microphthalmia, abnormal beaks, amelia, micromelia, ectrodactyly, and hydrocephaly. Mean concentrations of selenium in livers (94.4 ppm, dry weight) and kidneys (96.6 ppm) of birds collected at the Kesterson ponds were about 10 times those found at a nearby control area (8.3 and 12.2 ppm). We conclude that selenium present in the agricultural drainage water supplied to the Kesterson ponds accumulated in the food chain of aquatic birds to toxic concentrations and caused the lesion and other changes observed.

  10. Selenium and tellurium as carbon substitutes

    International Nuclear Information System (INIS)

    Knapp, F.F. Jr.

    1980-01-01

    This review has summarized structure-activity studies with 75 Se- and /sup 123m/Te-labeled radiopharmaceuticals in which the selenium or tellurium heteroatom has been inserted between carbon-carbon bonds. The agents that have been investigated in most detail include steroids for adrenal imaging and long-chain fatty acids, and a variety of other unique agents have also been studied. Because of the great versatility of the organic chemistry of selenium and tellurium, there is continuing interest in the preparation of radiopharmaceuticals labeled with 75 Se, 73 Se, and /sup 123m/Te. There are two important factors which will determine the extent of future interest in such agents. These include the necessity of a decrease in the cost of highly enriched 122 Te to make the reactor production of /sup 123m/Te cost effective. In addition, the potential preparation of large amounts of 73 Se should stimulate the development of 73 Se-labeled radiopharmaceuticals

  11. Biofortification and phytoremediation of selenium in China

    Directory of Open Access Journals (Sweden)

    Zhilin eWu

    2015-03-01

    Full Text Available Selenium (Se is an essential trace element for humans and animals but at high concentrations, Se becomes toxic to organisms due to Se replacing sulfur in proteins. Selenium biofortification is an agricultural process that increases the accumulation of Se in crops, through plant breeding, genetic engineering, or use of Se fertilizers. While Se phytoremediation is a green biotechnology to clean up Se-contaminated environments, primarily through phytoextraction and phytovolatilization. By integrating Se phytoremediation and biofortification technologies, Se-enriched plant materials harvested from Se phytoremediation can be used as Se-enriched green manures or other supplementary sources of Se for producing Se-biofortified agricultural products. Earlier studies primarily aimed at enhancing efficacy of phytoremediation and biofortification of Se based on natural variation in progenitor or identification of unique plant species. In this review, we discuss promising approaches to improve biofortification and phytoremediation of Se using knowledge acquired from model crops. We also explored the feasibility of applying biotechnologies such as inoculation of microbial strains for improving the efficiency of biofortification and phytoremediation of Se. The key research and practical challenges that remain in improving biofortification and phytoremediation of Se have been highlighted, and the future development and uses of Se-biofortified agricultural products in China has also been discussed.

  12. Selenium for the Prevention of Cutaneous Melanoma

    Directory of Open Access Journals (Sweden)

    Douglas Grossman

    2013-03-01

    Full Text Available The role of selenium (Se supplementation in cancer prevention is controversial; effects often depend on the nutritional status of the subject and on the chemical form in which Se is provided. We used a combination of in vitro and in vivo models to study two unique therapeutic windows for intervention in the process of cutaneous melanomagenisis, and to examine the utility of two different chemical forms of Se for prevention and treatment of melanoma. We studied the effects of Se in vitro on UV-induced oxidative stress in melanocytes, and on apoptosis and cell cycle progression in melanoma cells. In vivo, we used the HGF transgenic mouse model of UV-induced melanoma to demonstrate that topical treatment with l-selenomethionine results in a significant delay in the time required for UV-induced melanoma development, but also increases the rate of growth of those tumors once they appear. In a second mouse model, we found that oral administration of high dose methylseleninic acid significantly decreases the size of human melanoma xenografts. Our findings suggest that modestly elevation of selenium levels in the skin might risk acceleration of growth of incipient tumors. Additionally, certain Se compounds administered at very high doses could have utility for the treatment of fully-malignant tumors or prevention of recurrence.

  13. Photonic crystals, amorphous materials, and quasicrystals.

    Science.gov (United States)

    Edagawa, Keiichi

    2014-06-01

    Photonic crystals consist of artificial periodic structures of dielectrics, which have attracted much attention because of their wide range of potential applications in the field of optics. We may also fabricate artificial amorphous or quasicrystalline structures of dielectrics, i.e. photonic amorphous materials or photonic quasicrystals. So far, both theoretical and experimental studies have been conducted to reveal the characteristic features of their optical properties, as compared with those of conventional photonic crystals. In this article, we review these studies and discuss various aspects of photonic amorphous materials and photonic quasicrystals, including photonic band gap formation, light propagation properties, and characteristic photonic states.

  14. Selenium Level and Dyslipidemia in Rural Elderly Chinese.

    Directory of Open Access Journals (Sweden)

    Liqin Su

    Full Text Available Higher selenium level has been hypothesized to have the potential to reduce the risk of cardiovascular diseases including dyslipidemia. However, results from previous studies are inconsistent. This study aims to determine the association between selenium level and dyslipidemia in elderly Chinese with relatively low selenium status.A cross-sectional study of 1859 participants aged 65 or older from four rural counties in China was conducted. Serum total cholesterol (TC, triglycerides (TG, high density lipoprotein-cholesterol (HDLC and low-density lipoprotein-cholesterol (LDLC, nail selenium concentration and APOE genotype were measured in all subjects. The four types of dyslipidemia were defined as >5.17 mmol/L for High-TC, >1.69 mmol/L for High-TG, >3.36 mmol/L for High-LDLC, and <1.04 mmol/L for Low-HDLC according to Chinese Guidelines on Prevention and Treatment of Dyslipidemia in Adults. Logistic models adjusting for age, gender, APOE genotype, body mass index, alcohol consumption, smoking, physical activity, medication use for cardiovascular diseases were used to examine the relationship between selenium levels and the risk of dyslipidemia.Mean nail selenium concentration was 0.465 μg/gin this sample. Rates for High-TC, High-LDLC, High-TG, Low-HDLC were 18.13%, 13.23%, 12.21% and 32.76% respectively. Results from logistic models indicated that higher selenium levels were significantly associated with higher risk of High-TC, High-LDLC and lower risk of Low-HDLC adjusting for covariates (p < 0.0001. Compared with the lowest selenium quartile group, participants in selenium quartile groups 2, 3 and 4 had significantly higher rates of High-TC, High-LDLC, High-TG, and lower rate of Low-HDLC adjusting for covariates. No significant association was observed between selenium level and the risk of High-TG. APOEε4 carriers had higher rates of High-TC and High-LDLC. There was no interaction between selenium level and APOE with the rates of

  15. An Introduction to Testing Web Applications with twill and Selenium

    CERN Document Server

    Brown, Titus; Huggins, Jason

    2007-01-01

    This Short Cut is an introduction tobuilding automated web tests using twotools, twill and Selenium. twill is a simpleweb scripting language that can be usedto automate web tests, while Selenium isa web testing framework that runs in anybrowser and can be used to test complexweb sites that make extensive use ofJavaScript. The best way to use this Short Cut is torun through the examples. We expectthat within an hour you can start writingyour own functional tests in either twillor Selenium, and within a day you willunderstand most, if not all, of the possibilitiesand the limitations of these t

  16. Microgravimetric Studies of Selenium Electrodeposition Onto Different Substrates

    Directory of Open Access Journals (Sweden)

    Kowalik R.

    2014-10-01

    Full Text Available The mechanism of selenium electrodeposition from sulfuric acid solution on different substrates was studied with the electrochemical techniques. The cyclic voltammetry was combined with the quartz crystal microbalance technique to analyze selenium deposition process. The electrochemical reduction of selenous acid on gold, silver and copper electrodes was investigated. It was found that reduction of selenous acid is a very complex process and it strongly depends from the applied substrate. The voltammetric measurements indicate the range of potentials in which the process of reduction of selenous acids on the applied substrate is possible. Additionally, the microgravimetric data confirm the deposition of selenium and they reveal the mechanism of the deposition process.

  17. Selenium speciation in phosphate mine soils and evaluation of a sequential extraction procedure using XAFS

    Energy Technology Data Exchange (ETDEWEB)

    Favorito, Jessica E.; Luxton, Todd P.; Eick, Matthew J.; Grossl, Paul R. (VP); (Utah SU); (EPA)

    2017-10-01

    Selenium is a trace element found in western US soils, where ingestion of Se-accumulating plants has resulted in livestock fatalities. Therefore, a reliable understanding of Se speciation and bioavailability is critical for effective mitigation. Sequential extraction procedures (SEP) are often employed to examine Se phases and speciation in contaminated soils but may be limited by experimental conditions. We examined the validity of a SEP using X-ray absorption spectroscopy (XAS) for both whole and a sequence of extracted soils. The sequence included removal of soluble, PO4-extractable, carbonate, amorphous Fe-oxide, crystalline Fe-oxide, organic, and residual Se forms. For whole soils, XANES analyses indicated Se(0) and Se(-II) predominated, with lower amounts of Se(IV) present, related to carbonates and Fe-oxides. Oxidized Se species were more elevated and residual/elemental Se was lower than previous SEP results from ICP-AES suggested. For soils from the SEP sequence, XANES results indicated only partial recovery of carbonate, Fe-oxide and organic Se. This suggests Se was incompletely removed during designated extractions, possibly due to lack of mineral solubilization or reagent specificity. Selenium fractions associated with Fe-oxides were reduced in amount or removed after using hydroxylamine HCl for most soils examined. XANES results indicate partial dissolution of solid-phases may occur during extraction processes. This study demonstrates why precautions should be taken to improve the validity of SEPs. Mineralogical and chemical characterizations should be completed prior to SEP implementation to identify extractable phases or mineral components that may influence extraction effectiveness. Sequential extraction procedures can be appropriately tailored for reliable quantification of speciation in contaminated soils.

  18. Mercury-selenium relationships in liver of Guiana dolphin: the possible role of Kupffer cells in the detoxification process by tiemannite formation.

    Directory of Open Access Journals (Sweden)

    José Lailson-Brito

    Full Text Available Top marine predators present high mercury concentrations in their tissues as consequence of biomagnification of the most toxic form of this metal, methylmercury (MeHg. The present study concerns mercury accumulation by Guiana dolphins (Sotalia guianensis, highlighting the selenium-mediated methylmercury detoxification process. Liver samples from 19 dolphins incidentally captured within Guanabara Bay (Rio de Janeiro State, Brazil from 1994 to 2006 were analyzed for total mercury (THg, methylmercury (MeHg, total organic mercury (TOrgHg and selenium (Se. X-ray microanalyses were also performed. The specimens, including from fetuses to 30-year-old dolphins, comprising 8 females and 11 males, presented high THg (0.53-132 µg/g wet wt. and Se concentrations (0.17-74.8 µg/g wet wt.. Correlations between THg, MeHg, TOrgHg and Se were verified with age (p<0.05, as well as a high and positive correlation was observed between molar concentrations of Hg and Se (p<0.05. Negative correlations were observed between THg and the percentage of MeHg contribution to THg (p<0.05, which represents a consequence of the selenium-mediated methylmercury detoxification process. Accumulation of Se-Hg amorphous crystals in Kupffer Cells was demonstrated through ultra-structural analysis, which shows that Guiana dolphin is capable of carrying out the demethylation process via mercury selenide formation.

  19. Mercury-selenium relationships in liver of Guiana dolphin: the possible role of Kupffer cells in the detoxification process by tiemannite formation.

    Science.gov (United States)

    Lailson-Brito, José; Cruz, Renato; Dorneles, Paulo Renato; Andrade, Leonardo; Azevedo, Alexandre de Freitas; Fragoso, Ana Bernadete; Vidal, Lara Gama; Costa, Marianna Badini; Bisi, Tatiana Lemos; Almeida, Ronaldo; Carvalho, Dario Pires; Bastos, Wanderley Rodrigues; Malm, Olaf

    2012-01-01

    Top marine predators present high mercury concentrations in their tissues as consequence of biomagnification of the most toxic form of this metal, methylmercury (MeHg). The present study concerns mercury accumulation by Guiana dolphins (Sotalia guianensis), highlighting the selenium-mediated methylmercury detoxification process. Liver samples from 19 dolphins incidentally captured within Guanabara Bay (Rio de Janeiro State, Brazil) from 1994 to 2006 were analyzed for total mercury (THg), methylmercury (MeHg), total organic mercury (TOrgHg) and selenium (Se). X-ray microanalyses were also performed. The specimens, including from fetuses to 30-year-old dolphins, comprising 8 females and 11 males, presented high THg (0.53-132 µg/g wet wt.) and Se concentrations (0.17-74.8 µg/g wet wt.). Correlations between THg, MeHg, TOrgHg and Se were verified with age (p<0.05), as well as a high and positive correlation was observed between molar concentrations of Hg and Se (p<0.05). Negative correlations were observed between THg and the percentage of MeHg contribution to THg (p<0.05), which represents a consequence of the selenium-mediated methylmercury detoxification process. Accumulation of Se-Hg amorphous crystals in Kupffer Cells was demonstrated through ultra-structural analysis, which shows that Guiana dolphin is capable of carrying out the demethylation process via mercury selenide formation.

  20. Comparative effect of selenium and selenium tolerant microbes on brachiaria reptans l. growth

    International Nuclear Information System (INIS)

    Yasin, M.; Faisal, M.

    2014-01-01

    Brachiaria reptans L. is an annual grass. It is good fodder grass which is distributed in tropical Asia, Kenya, Pakistan and India and introduced throughout the tropics. In present study we determine the growth correlation among B. reptans, selenium (Se) and two Se tolerant bacteria (Bacillus licheniformis-YAP7 and Bacillus cereus-YAP6). Plants treated with Se showed a significant decrease in shoot length (33%) and fresh biomass (41%) compared to control. When plants were co-cultivated in the presence of bacteria or Se and bacteria both the shoot length increased (16-34%) significantly compared to control. B. reptans plants treated with Se have shown a significant decrease in peroxidase contents (59%) compared to control. However, bacterial inoculation of Se treated plants resulted in significant increase in peroxidase contents (113-171%). Selenium treatment caused increase in leaf soluble protein contents compared to control. In conclusion, bacteria can enhance B. reptans growth under Se stress. (author)

  1. Corrosion resistant amorphous metals and methods of forming corrosion resistant amorphous metals

    Science.gov (United States)

    Farmer, Joseph C [Tracy, CA; Wong, Frank M. G. [Livermore, CA; Haslam, Jeffery J [Livermore, CA; Yang, Nancy [Lafayette, CA; Lavernia, Enrique J [Davis, CA; Blue, Craig A [Knoxville, TN; Graeve, Olivia A [Reno, NV; Bayles, Robert [Annandale, VA; Perepezko, John H [Madison, WI; Kaufman, Larry [Brookline, MA; Schoenung, Julie [Davis, CA; Ajdelsztajn, Leo [Walnut Creek, CA

    2009-11-17

    A system for coating a surface comprises providing a source of amorphous metal, providing ceramic particles, and applying the amorphous metal and the ceramic particles to the surface by a spray. The coating comprises a composite material made of amorphous metal that contains one or more of the following elements in the specified range of composition: yttrium (.gtoreq.1 atomic %), chromium (14 to 18 atomic %), molybdenum (.gtoreq.7 atomic %), tungsten (.gtoreq.1 atomic %), boron (.ltoreq.5 atomic %), or carbon (.gtoreq.4 atomic %).

  2. Surface magnetic structures in amorphous ferromagnetic microwires

    International Nuclear Information System (INIS)

    Usov, N.A.; Serebryakova, O.N.; Gudoshnikov, S.A.; Tarasov, V.P.

    2017-01-01

    The spatial period of magnetization perturbations that occur near the surface of magnetic nanotube or nanowire under the influence of surface magnetic anisotropy is determined by means of numerical simulation as a function of the sample geometry and material parameters. The surface magnetization distribution obtained is then used to estimate the period of the surface magnetic texture in amorphous microwire of several micrometers in diameter by means of appropriate variational procedure. The period of the surface magnetic texture in amorphous microwire is found to be significantly smaller than the wire diameter. - Highlights: • Magnetic structure may arise near the magnetic nanotube surface under the influence of surface magnetic anisotropy. • The period of the surface magnetization pattern is calculated as a function of the sample geometry. • Similar magnetic structure may exist in amorphous microwire of several micrometers in diameter. • The period of the surface magnetic structure in amorphous wire is found to be significantly smaller than the wire diameter.

  3. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    2004-01-01

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio...... and a low glass transition temperature. The alloys were prepared by using a relatively simple technique, i.e. rapid cooling of the melt in a copper wedge mould. The essential structural changes that are achieved by going from the amorphous to the crystalline state through the supercooled liquid state...... are discussed in this paper. On the basis of these measurements phase diagrams of the different systems were constructed. Finally, it is demonstrated that when pressing the bulk amorphous alloy onto a metallic dies at temperatures within the supercooled liquid region, the alloy faithfully replicates the surface...

  4. Theoretical Considerations in Developing Amorphous Solid Dispersions

    DEFF Research Database (Denmark)

    Laitinen, Riikka; Priemel, Petra Alexandra; Surwase, Sachin

    2014-01-01

    to their glass-forming ability and glass stability. In the main parts of this chapter, we review theoretical approaches to determine amorphous drug polymer miscibility and crystalline drug polymer solubility, as a prerequisite to develop amorphous solid dispersions (glass solutions).......Before pursuing the laborious route of amorphous solid dispersion formulation and development, which is the topic of many of the subsequent chapters in this book, the formulation scientist would benefit from a priori knowledge whether the amorphous route is a viable one for a given drug and how...... much solubility improvement, and hence increase in bioavailability, can be expected, and what forms of solid dispersion have been developed in the past. In this chapter, we therefore initially define the various forms of solid dispersions, and then go on to discuss properties of pure drugs with respect...

  5. Surface magnetic structures in amorphous ferromagnetic microwires

    Energy Technology Data Exchange (ETDEWEB)

    Usov, N.A., E-mail: usov@obninsk.ru [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, IZMIRAN, 108840 Troitsk, Moscow (Russian Federation); Serebryakova, O.N.; Gudoshnikov, S.A. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, IZMIRAN, 108840 Troitsk, Moscow (Russian Federation); Tarasov, V.P. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation)

    2017-05-01

    The spatial period of magnetization perturbations that occur near the surface of magnetic nanotube or nanowire under the influence of surface magnetic anisotropy is determined by means of numerical simulation as a function of the sample geometry and material parameters. The surface magnetization distribution obtained is then used to estimate the period of the surface magnetic texture in amorphous microwire of several micrometers in diameter by means of appropriate variational procedure. The period of the surface magnetic texture in amorphous microwire is found to be significantly smaller than the wire diameter. - Highlights: • Magnetic structure may arise near the magnetic nanotube surface under the influence of surface magnetic anisotropy. • The period of the surface magnetization pattern is calculated as a function of the sample geometry. • Similar magnetic structure may exist in amorphous microwire of several micrometers in diameter. • The period of the surface magnetic structure in amorphous wire is found to be significantly smaller than the wire diameter.

  6. Amorphous Phases on the Surface of Mars

    Science.gov (United States)

    Rampe, E. B.; Morris, R. V.; Ruff, S. W.; Horgan, B.; Dehouck, E.; Achilles, C. N.; Ming, D. W.; Bish, D. L.; Chipera, S. J.

    2014-01-01

    Both primary (volcanic/impact glasses) and secondary (opal/silica, allophane, hisingerite, npOx, S-bearing) amorphous phases appear to be major components of martian surface materials based on orbital and in-situ measurements. A key observation is that whereas regional/global scale amorphous components include altered glass and npOx, local scale amorphous phases include hydrated silica/opal. This suggests widespread alteration at low water-to-rock ratios, perhaps due to snow/ice melt with variable pH, and localized alteration at high water-to-rock ratios. Orbital and in-situ measurements of the regional/global amorphous component on Mars suggests that it is made up of at least three phases: npOx, amorphous silicate (likely altered glass), and an amorphous S-bearing phase. Fundamental questions regarding the composition and the formation of the regional/global amorphous component(s) still remain: Do the phases form locally or have they been homogenized through aeolian activity and derived from the global dust? Is the parent glass volcanic, impact, or both? Are the phases separate or intimately mixed (e.g., as in palagonite)? When did the amorphous phases form? To address the question of source (local and/or global), we need to look for variations in the different phases within the amorphous component through continued modeling of the chemical composition of the amorphous phases in samples from Gale using CheMin and APXS data. If we find variations (e.g., a lack of or enrichment in amorphous silicate in some samples), this may imply a local source for some phases. Furthermore, the chemical composition of the weathering products may give insight into the formation mechanisms of the parent glass (e.g., impact glasses contain higher Al and lower Si [30], so we might expect allophane as a weathering product of impact glass). To address the question of whether these phases are separate or intimately mixed, we need to do laboratory studies of naturally altered samples made

  7. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  8. Amorphization Mechanism of Icosahedral Platinum Clusters

    International Nuclear Information System (INIS)

    Apra, Edoardo; Baletto, Francesca; Ferrando, Riccardo; Fortunelli, Alessandro

    2004-01-01

    The amorphization mechanism of high-symmetry pt nanoclusters is investigated by a combination of Molecular Dynamics simulations and Density Functional calculations. A general mechanism for amorphization, involving rosette-like structural transformations at fivefold vertices, is proposed. IN the tosette, a fivefold vertex is transformed into a hexagonal ring. We show that for icosahedral Pt nanoclusters, this transformation is associated with an energy gain, so that their most favorable structures have a low symmetry even at icosahedral magic numbers

  9. A Magnetic Sensor with Amorphous Wire

    Directory of Open Access Journals (Sweden)

    Dongfeng He

    2014-06-01

    Full Text Available Using a FeCoSiB amorphous wire and a coil wrapped around it, we have developed a sensitive magnetic sensor. When a 5 mm long amorphous wire with the diameter of 0.1 mm was used, the magnetic field noise spectrum of the sensor was about 30 pT/ÖHz above 30 Hz. To show the sensitivity and the spatial resolution, the magnetic field of a thousand Japanese yen was scanned with the magnetic sensor.

  10. Arsenic, chromium, copper, iron, manganese, lead, selenium and ...

    African Journals Online (AJOL)

    Arsenic, chromium, copper, iron, manganese, lead, selenium and zinc in the tissues of the largemouth yellowfish, Labeobarbus kimberleyensis (Gilchrist and Thompson, 1913), from the Vaal Dam, South Africa, and associated consumption risks.

  11. Mixed Surfactant Template Method for Preparation of Nanometer Selenium

    Directory of Open Access Journals (Sweden)

    Zhi-Lin Li

    2009-01-01

    Full Text Available Selenium nanoparticles have been synthesized in an aqueous solution by using sodium dodecyl sulfate and polyvinyl alcohol as a soft template. The factors on synthesis, such as reaction time, concentration of reactants and ultrasonic irradiation were studied. The uniform stable selenium nanospheres were obstained in the conditions of 1.0 (mass fraction sodium dodecyl sulfate, 1.0 (mass fraction polyvinyl alcohol, n(Vc:n(H2SeO3=7:1 and 7 minutes after the initiation of the reaction at room temperature. The average particle size of selenium is about 30 nm. The product was characterized by UV and TEM. Finally the applications of the red element nanometer selenium in anti-older cosmetics are presented.

  12. Geographical distribution of the selenium status of herbivores in ...

    African Journals Online (AJOL)

    Unknown

    : jvryssen@postino.up.ac.za. Introduction. The decision to provide selenium (Se) as a supplement to natural pastures for grazing livestock should be based on the anticipated response to supplementation at that specific locality. This requires.

  13. Male infertility: decreased levels of selenium, zinc and antioxidants.

    Science.gov (United States)

    Türk, Silver; Mändar, Reet; Mahlapuu, Riina; Viitak, Anu; Punab, Margus; Kullisaar, Tiiu

    2014-04-01

    In this study, we aimed to compare the level of zinc, selenium, glutathione peroxidase activity and antioxidant status in following populations of men: severe inflammation in prostate (>10(6) white blood cells in prostate secretion; n=29), severe leukocytospermia, (>10(6) white blood cells in semen; n=31), mild inflammation, (0.2-1M white blood cells in semen or prostate secretion; n=24), non-inflammatory oligozoospermia (n=32) and healthy controls (n=27). Male partners of infertile couples had reduced level of antioxidative activity, selenium and zinc in their seminal plasma. Most importantly, reduced selenium levels were evident in all patient groups regardless of inflammation status. Therefore, these patients might gain some benefit from selenium supplementation. Copyright © 2014. Published by Elsevier GmbH.

  14. Catalytic oxidant scavenging by selenium-containing compounds

    DEFF Research Database (Denmark)

    Carroll, Luke; Pattison, David I; Fu, Shanlin

    2017-01-01

    Myeloperoxidase produces strong oxidants during the immune response to destroy invading pathogens. However, these oxidants can also cause tissue damage, which contributes to the development of numerous inflammatory diseases. Selenium containing compounds, including selenomethionine (SeMet) and 1,...

  15. Protective effect of selenium on radiation-induced HPRT mutation

    International Nuclear Information System (INIS)

    Fan Feiyue; Yang Suxia; Cao Zhenshan; Li Yu; Liu Guolian

    2000-01-01

    Mutation of HPRT in human embryo lung cells induced by γ-ray was analyzed by way of CB. Efficiency of HPRT mutation was gradually increased with increasing of γ-ray doses after-irradiation. The relationship between mutation efficiency and radiation dose showed linear relative. The efficiency of HPRT mutation in cells exposed to γ-ray and selenium was lower than that in cells exposed to γ-ray only. This indicated that selenium possessed protective effect on HPRT mutation induced by γ-ray. This protective effect of selenium was more efficient when the cells were exposed to lower dose of γ-ray than to higher dose. The character of protective effect of selenium is very significant in medical protection on people exposed to low dose of radiation

  16. Selenium derivatives of thyroxine and tri-iodothyronine

    International Nuclear Information System (INIS)

    Cree, G.M.

    1980-01-01

    Novel selenium derivatives of thyroxine and tri-iodothyronine are described. They preferably contain at least one 75 Se atom. The compounds are useful in dual isotope assays of thyroid function. (U.K.)

  17. Selenium- or tellurium- containing bile acids and derivatives thereof

    International Nuclear Information System (INIS)

    Monks, R.; Riley, A.L.M.

    1981-01-01

    This invention relates to the preparation of selenium and tellurium derivatives, particularly γ-emitting radioactive derivatives of bile acids and bile salts. Such compounds are valuable in the examination of body function, especially small bowel function. (author)

  18. Selenium content of milk and milk products of Turkey. II.

    Science.gov (United States)

    Yanardağ, R; Orak, H

    1999-04-01

    Selenium content of 1028 milk and milk products of Turkey are presented in this study. The selenium content of human milk (colostrum, transitional, and mature milk), various kinds of milk [cow, sheep, goat, buffalo, paper boxes (3%, 1.5%, 0.012% fat), bottled milk, condensed milk (10% fat), mineral added milk (1.6%), and banana, strawberry, and chocolate milk] and milk products (kefir, yogurt, Ayran, various cheese, coffee cream, ice cream, butter, margarine, milk powder, and fruit yogurt) in Turkey were determined by a spectrofluorometric method. The selenium levels of cow milks collected from 57 cities in Turkey were also determined. Selenium levels in cow milk varied with geographical location in Turkey and were found to be lowest for Van and highest for Aksaray. The results [milk (cow, sheep, goat, buffalo and human) and milks products] were compared with literature data from different countries.

  19. Biomarkers of selenium status in dogs.

    Science.gov (United States)

    van Zelst, Mariëlle; Hesta, Myriam; Gray, Kerry; Staunton, Ruth; Du Laing, Gijs; Janssens, Geert P J

    2016-01-19

    Inadequate dietary selenium (Se) intake in humans and animals can lead to long term health problems, such as cancer. In view of the owner's desire for healthy longevity of companion animals, the impact of dietary Se provision on long term health effects warrants investigation. Little is currently known regards biomarkers, and rate of change of such biomarkers in relation to dietary selenium intake in dogs. In this study, selected biomarkers were assessed for their suitability to detect changes in dietary Se in adult dogs within eight weeks. Twenty-four dogs were fed a semi-purified diet with an adequate amount of Se (46.1 μg/MJ) over an 8 week period. They were then divided into two groups. The first group remained on the adequate Se diet, the second were offered a semi-purified diet with a low Se concentration (6.5 μg/MJ; 31% of the FEDIAF minimum) for 8 weeks. Weekly urine and blood was collected and hair growth measurements were performed. The urinary Se to creatinine ratio and serum Se concentration were significantly lower in dogs consuming the low Se diet from week 1 onwards, by 84% (adequate 25.3, low 4.1) and 7% (adequate 257 μg/L, low 238 μg/L) respectively. Serum and whole blood glutathione peroxidase were also significantly lower in dogs consuming the low Se diet from weeks 6 and 8 respectively. None of the other biomarkers (mRNA expression and serum copper, creatine kinase, triiodothyronine:thyroxine ratio and hair growth) responded significantly to the low Se diet over the 8 week period. This study demonstrated that urinary Se to creatinine ratio, serum Se and serum and whole blood glutathione peroxidase can be used as biomarkers of selenium status in dogs. Urinary Se to creatinine ratio and serum Se concentrations responded faster to decreased dietary Se than the other parameters. This makes these biomarkers candidates for early screening of long term effects of dietary Se provision on canine health.

  20. Mercury and selenium levels, and selenium:mercury molar ratios of brain, muscle and other tissues in bluefish (Pomatomus saltatrix) from New Jersey, USA

    Science.gov (United States)

    Burger, Joanna; Jeitner, Christian; Donio, Mark; Pittfield, Taryn; Gochfeld, Michael

    2015-01-01

    A number of contaminants affect fish health, including mercury and selenium, and the selenium: mercury molar ratio. Recently the protective effects of selenium on methylmercury toxicity have been publicized, particularly for consumption of saltwater fish. Yet the relative ameliorating effects of selenium on toxicity within fish have not been examined, nor has the molar ratio in different tissues, (i.e. brain). We examined mercury and selenium levels in brain, kidney, liver, red and white muscle, and skin and scales in bluefish (Pomatomus saltatrix) from New Jersey to determine whether there were toxic levels of either metal, and we computed the selenium: mercury molar ratios by tissues. Total mercury averaged 0.32 ± 0.02 ppm wet weight in edible muscle and 0.09 ± 0.01 ppm in brain. Selenium concentration averaged 0.37 ± 0.03 in muscle and 0.36 ± 0.03 ppm in brain. There were significant differences in levels of mercury, selenium, and selenium: mercury molar ratios, among tissues. Mercury and selenium levels were correlated in kidney and skin/scales. Mercury levels were highest in kidney, intermediate in muscle and liver, and lowest in brain and skin/scales; selenium levels were also highest in kidney, intermediate in liver, and were an order of magnitude lower in the white muscle and brain. Mercury levels in muscle, kidney and skin/scales were positively correlated with fish size (length). Selenium levels in muscle, kidney and liver were positively correlated with fish length, but in brain; selenium levels were negatively correlated with fish length. The selenium: mercury molar ratio was negatively correlated with fish length for white muscle, liver, kidney, and brain, particularly for fish over 50 cm in length, suggesting that older fish experience less protective advantages of selenium against mercury toxicity than smaller fish, and that consumers of bluefish similarly receive less advantage from eating larger fish. PMID:23202378

  1. Effect of organic and inorganic selenium supplementation on growth ...

    African Journals Online (AJOL)

    Ninety-six thousand one-day-old AA broilers were randomly assigned to two groups, 5 replicates in each group, and 9,600 chickens for each replicate. In the control group, 0.3 part per million (ppm) inorganic selenium (Na2SeO3) was added to the diets; while in the experimental group, 0.3 ppm organic selenium ...

  2. Selenium hyperaccumulation offers protection from cell disruptor herbivores

    OpenAIRE

    Quinn, Colin F; Freeman, John L; Reynolds, Ray JB; Cappa, Jennifer J; Fakra, Sirine C; Marcus, Matthew A; Lindblom, Stormy D; Quinn, Erin K; Bennett, Lindsay E; Pilon-Smits, Elizabeth AH

    2010-01-01

    Abstract Background Hyperaccumulation, the rare capacity of certain plant species to accumulate toxic trace elements to levels several orders of magnitude higher than other species growing on the same site, is thought to be an elemental defense mechanism against herbivores and pathogens. Previous research has shown that selenium (Se) hyperaccumulation protects plants from a variety of herbivores and pathogens. Selenium hyperaccumulating plants sequester Se in discrete locations in the leaf pe...

  3. Selenium transformation in coal mine spoils: Its environmental impact assessment

    Energy Technology Data Exchange (ETDEWEB)

    Harness, J.; Atalay, A.; Koll, K.J.; Zhang, H.; Maggon, D.

    1991-12-31

    The objective of this program was to conduct an environmental impact assessment study for selenium from coal mine spoils. The use of in-situ lysimetry to predict selenium speciation, transformation, and mobility under natural conditions was evaluated. The scope of the study was to construct and test field-scale lysimeter and laboratory mini-column to assess mobility and speciation of selenium in coal mine overburden and soil systems; to conduct soil and groundwater sampling throughout the state of Oklahoma for an overall environmental impact assessment of selenium; and to conduct an in-depth literature review on the solubility, speciation, mobility, and toxicity of selenium from various sources. Groundwater and surface soil samples were also collected from each county in Oklahoma. Data collected from the lysimeter study indicated that selenium in the overburden of the abandoned mine site was mainly found in the selenite form. The amount of selenite found was too low and immobile to be of concern to the environment. The spoil had equilibrated long enough (over 50 years) that most of the soluble forms of selenium have already been lost. Examination of the overburden indicated the presence of pyrite crystals that precipitated over time. The laboratory mini-column study indicated that selenite is quite immobile and remained on the overburden material even after leaching with dilute acid. Data from groundwater samples indicated that based on the current permissible level for selenium in groundwater (0.01 mg Se/L), Oklahoma groundwater is widely contaminated with the element. However, according to the new regulation (0.05 mg Se/L), which is to be promulgated in 1992, only 9 of the 77 counties in the state exceed the limit.

  4. 21 CFR 520.2100 - Selenium, vitamin E capsules.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Selenium, vitamin E capsules. 520.2100 Section 520... to 1 milligram of selenium) and 56.2 milligrams of vitamin E (68 I.U.) (as d-alpha tocopheryl acid... of vitamin E (17 I.U.) (as d-alpha tocopheryl acid succinate.) (b) Sponsor. See No. 000061 in § 510...

  5. Nuclear-based methods for the study of selenium

    International Nuclear Information System (INIS)

    Spyrou, N.M.; Akanle, O.A.; Dhani, A.

    1988-01-01

    The essentiality of selenium to the human being and in particular its deficiency state, associated with prolonged inadequate dietary intake, have received considerable attention. In addition, the possible relationship between selenium and cancer and the claim that selenium may possess cancer-prevention properties have focused research effort. It has been observed in a number of studies on laboratory animals that selenium supplementation protects the animals against carcinogen-induced neoplastic growth in various organ sites, reduces the incidence of spontaneous mammary tumors, and suppresses the growth of transplanted tumor cells. In these research programs on the relationship between trace element levels and senile dementia and depression and the elemental changes in blood associated with selenium supplementation in a normal group of volunteers, it became obvious that in addition to establishing normal levels of elements in the population of interest, there was a more fundamental requirement for methods to be developed that would allow the study of the distribution of selenium in the body and its binding sites. The authors propose emission tomography and perturbed angular correlation as techniques worth exploring

  6. Selenium in the Blackfoot, Salt, and Bear River Watersheds

    Science.gov (United States)

    Hamilton, S.J.; Buhl, K.J.

    2005-01-01

    Nine stream sites in the Blackfoot River, Salt River, and Bear River watersheds in southeast Idaho, USA were sampled in May 2001 for water, surficial sediment, aquatic plants, aquatic invertebrates, and fish. Selenium was measured in these aquatic ecosystem components, and a hazard assessment was performed on the data. Water quality characteristics such as pH, hardness, and specific conductance were relatively uniform among the nine sites. Of the aquatic components assessed, water was the least contaminated with selenium because measured concentrations were below the national water quality criterion of 5 μ g/L at eight of the nine sites. In contrast, selenium was elevated in sediment, aquatic plants, aquatic invertebrates, and fish from several sites, suggesting deposition in sediments and food web cycling through plants and invertebrates. Selenium was elevated to concentrations of concern in fish at eight sites (> 4 μ g/g in whole body). A hazard assessment of selenium in the aquatic environment suggested a moderate hazard at upper Angus Creek (UAC) and Smoky Creek (SC), and high hazard at Little Blackfoot River (LiB), Blackfoot River gaging station (BGS), State Land Creek (SLC), upper (UGC) and lower Georgetown Creek (LGC), Deer Creek (DC), and Crow Creek (CC). The results of this study indicate that selenium concentrations from the phosphate mining area of southeast Idaho were sufficiently elevated in several ecosystem components to cause adverse effects to aquatic resources in southeastern Idaho.

  7. Selenium intake and metabolic syndrome: A systematic review.

    Science.gov (United States)

    Retondario, Anabelle; Fernandes, Ricardo; Rockenbach, Gabriele; Alves, Mariane de Almeida; Bricarello, Liliana Paula; Trindade, Erasmo Benicio Santos de Moraes; Vasconcelos, Francisco de Assis Guedes de

    2018-03-02

    Metabolic syndrome is a multi-causal disease. Its treatment includes lifestyle changes with a focus on weight loss. This systematic review assessed the association between Selenium intake and metabolic syndrome. Data were collected mainly from four databases: PubMed, CENTRAL (Cochrane), Scopus and Web of Knowledge. Keywords related to metabolic syndrome, selenium, as well as metabolic syndrome features were searched. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. A systematic review protocol was registered at PROSPERO (n. 42016046321). Two reviewers independently screened 2957 abstracts. Six studies were included to perform data extraction with standardized spreadsheets. The risk of bias was assessed by using specific tools according to the design of the relevant studies. An assessment was carried out based on the appropriateness of the study reports accordingly to STROBE and the CONSORT-based checklist for each study design. Three studies found no association between Selenium intake and metabolic syndrome; two of them found an inverse association; and one study found a direct association between Selenium intake and metabolic syndrome. One study also showed an inverse association between Selenium intake and the prevalence of high waist circumference, high diastolic blood pressure, and hyperglycaemia in women. Overall, based on the argumentation and results of this study, it is possible to conclude that Selenium intake and metabolic syndrome are not clearly associated in adults and elderly. Copyright © 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  8. Selenium concentrations of selected medicinal and aromatic plants in Turkey.

    Science.gov (United States)

    Ozkutlu, Faruk; Sekeroglu, Nazim; Koca, Ufuk; Yazici, Gizem

    2011-10-01

    Recent scientific studies have proven the importance of trace elements on human health. The main food supplies are plants and animals, which are significant sources of these minerals. Studies on determining mineral compositions of herbs, spices and some other crops have increased all over the world. Published works revealed that spices, herbs and medicinal plants should be consumed to obtain beneficial trace elements. Selenium (Se), one of the most vital trace elements, has a significant role in human diet acting as a preventative agent against some serious illnesses. Despite numerous scientific works on mineral compositions of medicinal and aromatic plants, investigations of selenium content in these foods could not be successfully studied until recently due to the lack of suitable analytical methods for selenium analysis. Thus, publications on selenium concentrations of foods are recent. In this regard, selenium contents of some medicinal and aromatic plants commonly used as spices, herbal teas and traditional medicines in Turkey were studied in the present research. Selenium contents of the most used parts of these plants were analyzed by ICP-OES (Varian Vista-Pro, Australia). Of the analyzed 26 medicinal and aromatic plants, the highest Se concentration (1133 microg kg-1) was found in sweet basil (Ocimum basilicum L.) and the lowest in sumac (Rhus coriaria L.) fruits (11 microg kg(-1)).

  9. Daily dietary selenium intake of selected Brazilian population groups

    International Nuclear Information System (INIS)

    Maihara, V.A.; Favaro, D.I.T.; Vasconcellos, M.B.A.; Gonzaga, I.B.; Silva, V.L.; Cozzolino, S.M.F.

    2004-01-01

    Due to its essential characteristics, the daily dietary selenium intake of individuals should be monitored accurately. Daily selenium intake of different Brazilian population groups based on duplicate portion diet analysis was evaluated and compared with the new estimated average requirement values (EAR), to assess if selenium deficiency or excess could be observed in these groups. Selenium content was determined by neutron activation analysis (NAA). The average daily dietary selenium intake found was 26.3 (±8.3) μg/day for children from the city of Sao Paulo, 37.4 (±16.0) μg/day for children from Belem, 107 (±107) μg/day for children from Macapa, 28.4 (±7.5) μg/day for institutionalized elderly, 32 (±6) μg/day for non-institutionalized elderly and 37 (±17) μg/day for university students from Sao Paulo. Most daily dietary selenium intake range observed were below the EAR values. The values obtained for children groups from Belem and Macapa cities, whose intake levels were much higher than the recommendation, were an exception. (author)

  10. Selenium content in milk and diary samples

    International Nuclear Information System (INIS)

    Kira, Carmen S.; Maihara, Vera A.

    2005-01-01

    Food is the primary source of Se for human beings. As such determining Se levels in foodstuffs become very important. However, information concerning Se levels in different sources of nutrition in different country, particularly in Brazil, is limited. Instrumental Neutron Activation Analysis (INAA) has been used to effectively determine micronutrient levels in foodstuffs, such as milk and dairy samples. The advantage of using the INAA technique is that the samples do not require previous dissolution before analysis. In this study, INAA was applied to determine Se concentration in milk and dairy products. The samples were acquired in the markets of Sao Paulo city. After a 8-hour irradiation in the research reactor IEA-R1, selenium was analyzed by gamma-ray spectrometry. Methodology validation was done analyzing NIST reference materials (Whole Milk Powder and Non Fat Milk Powder). Se concentrations in the sample analyzed were below 0.300 μg g -1 . (author)

  11. Effect of selenium supplementation on thyroid antibodies

    International Nuclear Information System (INIS)

    Kvicala, J.; Hrda, P.; Zamrazil, V.; Nemecek, J.; Hill, M.; Jiranek, V.

    2009-01-01

    Selenium is an essential component of selenoproteins, enzymes with extensive regulatory and protective effect in organism. Immunological effects of Se are documented and are distinct even above concentrations necessary for maximal activity of selenoenzymes. Therefore, we investigated effect of supplementation by 100 μg of yeast-bound Se on concentrations of thyroid autoantibodies TPOAb and TgAb in the group of 253 seniors living in the Asylum Houses of South Bohemia. Increase of serum selenium from 59 to 150 μg Se/L serum in supplemented group and from 59 to 72 μg Se/L serum in group with placebo were detected by Instrumental Neutron Activation Analysis (INAA) and proved increased Se intake during the trial. Autoantibodies were analyzed by ELISA at the beginning of the trial and after 1 year. Statistical evaluation of results in whole groups (regardless of increased autoantibodies) by ANOVA manifested significant decrease of TPOAb and TgAb in non-supplemented group while supplementation did not effect serum autoantibodies concentrations. Evaluation of groups of seniors created from those with increased autoantibodies, ANOVA demonstrated decrease of TPOAb in both groups but Se supplementation did not affect the decrease. In opposite, TgAb increased significantly and Se supplementation led to higher increase of TgAb. Recent results of possibility to decrease serum concentration of TPOAb proved this effect only for high TPOAb concentrations and for higher Se supplements. From this point of view, it is necessary to conduct subsequent trials with the patients with autoimmune thyreoiditis with different levels of autoantibodies and detect also serum Se levels. (author)

  12. [Digital cephalometrics

    NARCIS (Netherlands)

    Ongkosuwito, E.M.; Katsaros, C.; Bodegom, J.C.; Kuijpers-Jagtman, A.M.

    2004-01-01

    There are different methods to produce digital head films and all have advantages and disadvantages. With a digital head film and a computer programme for digital cephalometry an analysis can be performed easily. All existing computer programmes for digital cephalometry use reference values to

  13. Copper and selenium supplementation in the diet of Brangus steers on the nutritional characteristics of meat

    Directory of Open Access Journals (Sweden)

    Arlindo Saran Netto

    2013-01-01

    Full Text Available Twenty-eight Brangus cattle were used to determine the effect of copper and selenium supplementation on the carcass characteristics, fatty acid composition of the longissimus dorsi muscle and on the copper and selenium concentrations in the liver. The treatments were: no supplementation of copper or selenium; 2 mg Se/kg DM as sodium selenite; 40 mg Cu/kg DM as copper sulfate; and 2 mg Se/kg DM as sodium selenite and 40 mg Cu/kg DM as copper sulfate. The fat thickness, rib eye area and fatty acid composition of the longissimus dorsi muscle were not affected by treatments. There was no effect on carcass yield and cooling loss with the supplementation of copper, selenium or selenium × copper in the levels studied. For the ether extract concentration in the longissimus dorsi muscle, no differences were found according to the treatments with selenium, copper or selenium × copper. The treatments with selenium and selenium × copper showed higher selenium concentrations in the liver than the control and copper treatments. For the copper concentration in the liver, the copper and selenium × copper treatments showed higher values than the control and selenium treatments. Despite the little effect on the meat composition, the results of this experiment demonstrate no interaction between selenium and copper in the levels studied.

  14. Selenium levels in patients with autoimmune thyroiditis and controls in lower Austria.

    Science.gov (United States)

    Wimmer, I; Hartmann, T; Brustbauer, R; Minear, G; Dam, K

    2014-09-01

    Autoimmune thyroiditis (AIT) is one of the most common autoimmune diseases; genetic as well as environmental factors contribute to its pathogenesis. The thyroid is the organ with the highest selenium content per unit weight. Selenium status appears to have an impact on the development of thyroid pathologies. We investigated a possible difference of selenium serum levels as a marker of nutritional selenium supply between patients with AIT in central Lower Austria and a matched group of healthy persons living in the same region. Selenium serum levels in the patients with AIT were 98.0 ± 15.6 μg/l. A significant difference to the matched group of normal persons, whose selenium serum levels were 103.2 ± 12.4 μg/l, could not be detected by the t-test (p>0.05). We considered the serum selenium levels to be indicators of selenium supply (by alimentation). A serum level of 120-160 μg/l of selenium represents the normal range. According to this, most patients and control persons showed mild to moderate selenium deficiency (80-120 μg/l selenium). Although our data present slightly higher selenium levels in normal persons than in patients with AIT, this weak and statistically insignificant trend is not sufficient to support the conclusion of a link between inadequate selenium supply and autoimmune thyroid disease. © Georg Thieme Verlag KG Stuttgart · New York.

  15. Digital squares

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Kim, Chul E

    1988-01-01

    Digital squares are defined and their geometric properties characterized. A linear time algorithm is presented that considers a convex digital region and determines whether or not it is a digital square. The algorithm also determines the range of the values of the parameter set of its preimages. ....... The analysis involves transforming the boundary of a digital region into parameter space of slope and y-intercept......Digital squares are defined and their geometric properties characterized. A linear time algorithm is presented that considers a convex digital region and determines whether or not it is a digital square. The algorithm also determines the range of the values of the parameter set of its preimages...

  16. Ab initio simulation of amorphous silicon

    International Nuclear Information System (INIS)

    Cooper, N.C.; McKenzie, D.R.; Goringe, C.M.

    1999-01-01

    Full text: A first-principles Car-Parrinello molecular dynamics simulation of amorphous silicon is presented. Density Functional Theory is used to describe the forces between the atoms in a 64 atom supercell which is periodically repeated throughout space in order to generate an infinite network of atoms (a good approximation to a real solid). A quench from the liquid phase is used to achieve a quenched amorphous structure, which is subjected to an annealing cycle to improve its stability. The final, annealed network is in better agreement with experiment than any previous simulation of amorphous silicon. Significantly, the predicted average first-coordination numbers of 3.56 and 3.84 for the quenched and annealed structures from this simulation agree very closely with the experimental values of 3.55 and 3.90 respectively, whereas all previous simulations yielded first coordination numbers greater than 4. This improved agreement in coordination numbers is important because it supports the experimental finding that dangling bonds (which are associated with under-coordinated atoms) are more prevalent than floating bonds (the strained, longer bond of a five coordinate atom) in pure amorphous silicon. Finally, the effect of adding hydrogen to amorphous silicon was investigated by specifically placing hydrogen atoms at the likely defect sites. After a structural relaxation to optimise the positions of these hydrogen atoms, the localised electronic states associated with these defects are absent. Thus hydrogen is responsible for removing these defect states (which are able to trap carriers) from the edge of the band gap of the amorphous silicon. These results confirm the widely held ideas about the effect of hydrogen in producing remarkable improvements in the electronic properties of amorphous silicon

  17. Effects of the amorphization on hysteresis loops of the amorphous spin-1/2 Ising system

    International Nuclear Information System (INIS)

    Essaoudi, I.; Ainane, A.; Saber, M.; Miguel, J.J. de

    2009-01-01

    We examine the effects of the amorphization on the hysteresis loops of the amorphous spin-1/2 Ising system using the effective field theory within a probability distribution technique that accounts for the self-spin correlation functions. The magnetization, the transverse and longitudinal susceptibilities, and pyromagnetic coefficient are also studied in detail

  18. Loss of Selenium-Binding Protein 1 Decreases Sensitivity to Clastogens and Intracellular Selenium Content in HeLa Cells.

    Science.gov (United States)

    Zhao, Changhui; Zeng, Huawei; Wu, Ryan T Y; Cheng, Wen-Hsing

    2016-01-01

    Selenium-binding protein 1 (SBP1) is not a selenoprotein but structurally binds selenium. Loss of SBP1 during carcinogenesis usually predicts poor prognosis. Because genome instability is a hallmark of cancer, we hypothesize that SBP1 sequesters cellular selenium and sensitizes cancer cells to DNA-damaging agents. To test this hypothesis, we knocked down SBP1 expression in HeLa cervical cancer cells by employing a short hairpin RNA (shRNA) approach. Reduced sensitivity to hydrogen peroxide, paraquat and camptothecin, reactive oxygen species content, and intracellular retention of selenium after selenomethionine treatment were observed in SBP1 shRNA HeLa cells. Results from Western analyses showed that treatment of HeLa cells with selenomethionine resulted in increased SBP1 protein expression in a dose-dependent manner. Knockdown of SBP1 rendered HeLa cells increased expression of glutathione peroxidase-1 but not glutathione peroxidase-4 protein levels and accelerated migration from a wound. Altogether, SBP1 retains supplemental selenium and sensitizes HeLa cancer cells to clastogens, suggesting a new cancer treatment strategy by sequestering selenium through SBP1.

  19. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    Science.gov (United States)

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  20. Biological and chemical investigation of Allium cepa L. response to selenium inorganic compounds.

    Science.gov (United States)

    Michalska-Kacymirow, M; Kurek, E; Smolis, A; Wierzbicka, M; Bulska, E

    2014-06-01

    The aim of this study was to evaluate the biological and chemical response of Allium cepa L. exposed to inorganic selenium compounds. Besides the investigation of the total content of selenium as well as its chemical speciation, the Allium test was used to evaluate the growth of onion roots and mitotic activity in the roots' meristem. The total content of selenium was determined by inductively coupled plasma mass spectrometry (ICP MS). High-performance liquid chromatography (HPLC), coupled to ICP MS, was used for the selenium chemical speciation. Results indicated that A. cepa plants are able to biotransform inorganic selenium compounds into their organic derivatives, e.g., Se-methylselenocysteine from the Se(IV) inorganic precursor. Although the differences in the biotransformation of selenium are due mainly to the oxidation state of selenium, the experiment has also shown a fine effect of counter ions (H(+), Na(+), NH4 (+)) on the response of plants and on the specific metabolism of selenium.

  1. Transformation of Selenium-Containing Phases in Copper Anode Slimes During Leaching

    Science.gov (United States)

    Li, Xue Jiao; Yang, Hong Ying; Jin, Zhe Nan; Chen, Guo Bao; Tong, Lin Lin

    2017-10-01

    The transformation of selenium-containing phases in copper anode slimes during the leaching process was investigated based on the Eh-pH diagram, leaching efficiencies of metals, and characterization of the residues produced during leaching. The leaching efficiency of selenium increases slowly to 17.7% in the first 50 min and then more rapidly to 98.3% in the next 110 min. The Eh-pH diagram indicates that elemental selenium is an intermediate product of the oxidation of selenide to selenite. The x-ray powder diffraction data and scanning electron microscopy-energy-dispersive x-ray spectroscopy data demonstrate that selenium leaching can be divided into three stages. Ag-Cu selenide first transforms into silver selenide and then converts to elemental selenium. Finally, elemental selenium is dissolved as selenite. The intermediate product, elemental selenium, is the main reason for the slow initial leaching rate of selenium.

  2. Ta-based amorphous metal thin films

    Energy Technology Data Exchange (ETDEWEB)

    McGlone, John M., E-mail: mcglone@eecs.oregonstate.edu [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-5501 (United States); Olsen, Kristopher R. [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States); Stickle, William F.; Abbott, James E.; Pugliese, Roberto A.; Long, Greg S. [Hewlett-Packard Company, Corvallis, OR, 97333 (United States); Keszler, Douglas A. [Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003 (United States); Wager, John F. [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-5501 (United States)

    2015-11-25

    With their lack of grains and grain boundaries, amorphous metals are known to possess advantageous mechanical properties and enhanced chemical stability relative to crystalline metals. Commonly, however, they exhibit poor high-temperature stability because of their metastable nature. Here, we describe two new Ta-based ternary metal thin films that retain thermal stability to 600 °C and above. The new thin-film compositions, Ta{sub 2}Ni{sub 2}Si{sub 1} and Ta{sub 2}Mo{sub 2}Si{sub 1}, are amorphous, exhibiting ultra-smooth surfaces (<0.4 nm) and resistivities typical of amorphous metals (224 and 177 μΩ cm, respectively). - Highlights: • New Ta-based amorphous metals were sputter deposited from individual targets. • As-deposited amorphous structure was confirmed through diffraction techniques. • Electrical and surface properties were characterized and possess smooth surfaces. • No evidence of crystallization up to 600 °C (TaNiSi) and 800 °C (TaMoSi). • Ultra-smooth surfaces remained unchanged up to crystallization temperature.

  3. Amorphous silicon detectors in positron emission tomography

    International Nuclear Information System (INIS)

    Conti, M.; Perez-Mendez, V.

    1989-12-01

    The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters ε 2 τ's are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs

  4. Amorphous silicon detectors in positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Conti, M. (Istituto Nazionale di Fisica Nucleare, Pisa (Italy) Lawrence Berkeley Lab., CA (USA)); Perez-Mendez, V. (Lawrence Berkeley Lab., CA (USA))

    1989-12-01

    The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters {epsilon}{sup 2}{tau}'s are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs.

  5. The Structure of Liquid and Amorphous Hafnia

    Directory of Open Access Journals (Sweden)

    Leighanne C. Gallington

    2017-11-01

    Full Text Available Understanding the atomic structure of amorphous solids is important in predicting and tuning their macroscopic behavior. Here, we use a combination of high-energy X-ray diffraction, neutron diffraction, and molecular dynamics simulations to benchmark the atomic interactions in the high temperature stable liquid and low-density amorphous solid states of hafnia. The diffraction results reveal an average Hf–O coordination number of ~7 exists in both the liquid and amorphous nanoparticle forms studied. The measured pair distribution functions are compared to those generated from several simulation models in the literature. We have also performed ab initio and classical molecular dynamics simulations that show density has a strong effect on the polyhedral connectivity. The liquid shows a broad distribution of Hf–Hf interactions, while the formation of low-density amorphous nanoclusters can reproduce the sharp split peak in the Hf–Hf partial pair distribution function observed in experiment. The agglomeration of amorphous nanoparticles condensed from the gas phase is associated with the formation of both edge-sharing and corner-sharing HfO6,7 polyhedra resembling that observed in the monoclinic phase.

  6. Treating chronic arsenic toxicity with high selenium lentil diets

    Energy Technology Data Exchange (ETDEWEB)

    Sah, Shweta [Department of Ecosystem and Public Health, Faculty of Medicine, University of Calgary, Calgary, AB T2N 4Z6 (Canada); Vandenberg, Albert [Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8 (Canada); Smits, Judit, E-mail: judit.smits@ucalgary.ca [Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4Z6 (Canada)

    2013-10-01

    Arsenic (As) toxicity causes serious health problems in humans, especially in the Indo-Gangetic plains and mountainous areas of China. Selenium (Se), an essential micronutrient is a potential mitigator of As toxicity due to its antioxidant and antagonistic properties. Selenium is seriously deficient in soils world-wide but is present at high, yet non-toxic levels in the great plains of North America. We evaluate the potential of dietary Se in counteracting chronic As toxicity in rats through serum biochemistry, blood glutathione levels, immunotoxicity (antibody response), liver peroxidative stress, thyroid response and As levels in tissues and excreta. To achieve this, we compare diets based on high-Se Saskatchewan (SK) lentils versus low-Se lentils from United States. Rats drank control (0 ppm As) or As (40 ppm As) water while consuming SK lentils (0.3 ppm Se) or northwestern USA lentils (< 0.01 ppm Se) diets for 14 weeks. Rats on high Se diets had higher glutathione levels regardless of As exposure, recovered antibody responses in As-exposed group, higher fecal and urinary As excretion and lower renal As residues. Selenium deficiency caused greater hepatic peroxidative damage in the As exposed animals. Thyroid hormones, triiodothyronine (T3) and thyroxine (T4), were not different. After 14 weeks of As exposure, health indicators in rats improved in response to the high Se lentil diets. Our results indicate that high Se lentils have a potential to mitigate As toxicity in laboratory mammals, which we hope will translate into benefits for As exposed humans. - Highlights: • We reduce chronic arsenic toxicity in rats with a whole food solution. • High selenium lentils decrease liver damage and increase blood glutathione levels. • High selenium lentil diets increase urinary and fecal arsenic excretion. • High selenium lentil diets decrease arsenic levels in kidney, the storage organ. • High selenium lentil diets reverse arsenic suppression of the B cell

  7. Selenium redox biochemistry of zinc–sulfur coordination sites in proteins and enzymes

    OpenAIRE

    Jacob, Claus; Maret, Wolfgang; Vallee, Bert L.

    1999-01-01

    Selenium has been increasingly recognized as an essential element in biology and medicine. Its biochemistry resembles that of sulfur, yet differs from it by virtue of both redox potentials and stabilities of its oxidation states. Selenium can substitute for the more ubiquitous sulfur of cysteine and as such plays an important role in more than a dozen selenoproteins. We have chosen to examine zinc–sulfur centers as possible targets of selenium redox biochemistry. Selenium compounds release zi...

  8. Emerging trends in the stabilization of amorphous drugs

    DEFF Research Database (Denmark)

    Laitinen, Riikka; Löbmann, Korbinian; Strachan, Clare J.

    2013-01-01

    water-soluble drugs can be increased by the formation of stabilized amorphous forms. Currently, formulation as solid polymer dispersions is the preferred method to enhance drug dissolution and to stabilize the amorphous form of a drug. The purpose of this review is to highlight emerging alternative...... methods to amorphous polymer dispersions for stabilizing the amorphous form of drugs. First, an overview of the properties and stabilization mechanisms of amorphous forms is provided. Subsequently, formulation approaches such as the preparation of co-amorphous small-molecule mixtures and the use...

  9. A study of selenium nanoparticles as charge storage element for flexible semi-transparent memory devices

    Science.gov (United States)

    Alotaibi, Sattam; Nama Manjunatha, Krishna; Paul, Shashi

    2017-12-01

    Flexible Semi-Transparent electronic memory would be useful in coming years for integrated flexible transparent electronic devices. However, attaining such flexibility and semi-transparency leads to the boundaries in material composition. Thus, impeding processing speed and device performance. In this work, we present the use of inorganic stable selenium nanoparticles (Se-NPs) as a storage element and hydrogenated amorphous carbon (a-C:H) as an insulating layer in two terminal non-volatile physically flexible and semi-transparent capacitive memory devices (2T-NMDs). Furthermore, a-C:H films can be deposited at very low temperature (memory on a flexible substrate. Moreover, the memory behaviour of the Se-NPs was found to be more distinct than those of the semiconductor and metal nanostructures due to higher work function compared to the commonly used semiconductor and metal species. The memory behaviour was observed from the hysteresis of current-voltage (I-V) measurements while the two distinguishable electrical conductivity states (;0; and "1") were studied by current-time (I-t) measurements.

  10. FTIR and Raman spectroscopic studies of selenium nanoparticles synthesised by the bacterium Azospirillum thiophilum

    Science.gov (United States)

    Tugarova, Anna V.; Mamchenkova, Polina V.; Dyatlova, Yulia A.; Kamnev, Alexander A.

    2018-03-01

    Vibrational (Fourier transform infrared (FTIR) and Raman) spectroscopic techniques can provide unique molecular-level information on the structural and compositional characteristics of complicated biological objects. Thus, their applications in microbiology and related fields are steadily increasing. In this communication, biogenic selenium nanoparticles (Se NPs) were obtained via selenite (SeO32-) reduction by the bacterium Azospirillum thiophilum (strain VKM B-2513) for the first time, using an original methodology for obtaining extracellular NPs. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed the Se NPs to have average diameters within 160-250 nm; their zeta potential was measured to be minus 18.5 mV. Transmission FTIR spectra of the Se NPs separated from bacterial cells showed typical proteinacious, polysaccharide and lipid-related bands, in line with TEM data showing a thin layer covering the Se NPs surface. Raman spectra of dried Se NPs layer in the low-frequency region (under 500 cm-1 down to 150 cm-1) showed a single very strong band with a maximum at 250 cm-1 which, in line with its increased width (ca. 30 cm-1 at half intensity), can be attributed to amorphous elementary Se. Thus, a combination of FTIR and Raman spectroscopic approaches is highly informative in non-destructive analysis of structural and compositional properties of biogenic Se NPs.

  11. Formation of amorphous layers by irradiation

    International Nuclear Information System (INIS)

    Bourgoin, J.C.

    1979-01-01

    When an ordered solid is irradiated with heavy energy particles, disorder is produced. When the irradiation dose exceeds a so-called critical dose, the irradiated area of the solid becomes uniformly disordered. Mention is first made of the nature, concentration and distribution of the defects created by a heavy energy particle. The description is then given -solely with respect to semiconductors- of the effect of the various parameters on the critical dose energy and nature of the ion, nature and temperature of the solid, irradiation flux. The physical properties (electronic and thermodynamic types) and the uniformly disordered areas are briefly discussed and these properties are compared with those of amorphous semiconductor layers fabricated by evaporation. It is concluded that the evaporated and irradiated layers are similar in nature. It is suggested that the transformation of an irradiated crystalline area into an amorphous one occurs when the Gibbs energy of the crystal become greater than the Gibbs energy of the amorphous one [fr

  12. Phase transitions in biogenic amorphous calcium carbonate.

    Science.gov (United States)

    Gong, Yutao U T; Killian, Christopher E; Olson, Ian C; Appathurai, Narayana P; Amasino, Audra L; Martin, Michael C; Holt, Liam J; Wilt, Fred H; Gilbert, P U P A

    2012-04-17

    Crystalline biominerals do not resemble faceted crystals. Current explanations for this property involve formation via amorphous phases. Using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), here we examine forming spicules in embryos of Strongylocentrotus purpuratus sea urchins, and observe a sequence of three mineral phases: hydrated amorphous calcium carbonate (ACC · H(2)O) → dehydrated amorphous calcium carbonate (ACC) → calcite. Unexpectedly, we find ACC · H(2)O-rich nanoparticles that persist after the surrounding mineral has dehydrated and crystallized. Protein matrix components occluded within the mineral must inhibit ACC · H(2)O dehydration. We devised an in vitro, also using XANES-PEEM, assay to identify spicule proteins that may play a role in stabilizing various mineral phases, and found that the most abundant occluded matrix protein in the sea urchin spicules, SM50, stabilizes ACC · H(2)O in vitro.

  13. Fabrication and application of amorphous semiconductor devices

    International Nuclear Information System (INIS)

    Kumurdjian, Pierre.

    1976-01-01

    This invention concerns the design and manufacture of elecric switching or memorisation components with amorphous semiconductors. As is known some compounds, particularly the chalcogenides, have a resistivity of the semiconductor type in the amorphous solid state. These materials are obtained by the high temperature homogeneisation of several single elements such as tellurium, arsenic, germanium and sulphur, followed by water or air quenching. In particular these compounds have useful switching and memorisation properties. In particular they have the characteristic of not suffering deterioration when placed in an environment subjected to nuclear radiations. In order to know more about the nature and properties of these amorphous semiconductors the French patent No. 71 28048 of 30 June 1971 may be consulted with advantage [fr

  14. Heavy ions amorphous semiconductors irradiation study

    International Nuclear Information System (INIS)

    Benmalek, M.

    1978-01-01

    The behavior of amorphous semiconductors (germanium and germanium and arsenic tellurides) under ion bombardment at energies up to 2 MeV was studied. The irradiation induced modifications were followed using electrical parameter changes (resistivity and activation energy) and by means of the transmission electron microscopy observations. The electrical conductivity enhancement of the irradiated samples was interpreted using the late conduction theories in amorphous compounds. In amorphous germanium, Electron Microscopy showed the formations of 'globules', these defects are similar to voids observed in irradiated metals. The displacement cascade theory was used for the interpretation of the irradiation induced defects formation and a coalescence mechanism of growth was pointed out for the vacancy agglomeration [fr

  15. Digital Culture and Digital Library

    Directory of Open Access Journals (Sweden)

    Yalçın Yalçınkaya

    2016-12-01

    Full Text Available In this study; digital culture and digital library which have a vital connection with each other are examined together. The content of the research consists of the interaction of culture, information, digital culture, intellectual technologies, and digital library concepts. The study is an entry work to integrity of digital culture and digital library theories and aims to expand the symmetry. The purpose of the study is to emphasize the relation between the digital culture and digital library theories acting intersection of the subjects that are examined. Also the perspective of the study is based on examining the literature and analytical evaluation in both studies (digital culture and digital library. Within this context, the methodology of the study is essentially descriptive and has an attribute for the transmission and synthesis of distributed findings produced in the field of the research. According to the findings of the study results, digital culture is an inclusive term that describes the effects of intellectual technologies in the field of information and communication. Information becomes energy and the spectrum of the information is expanding in the vertical rise through the digital culture. In this context, the digital library appears as a new living space of a new environment. In essence, the digital library is information-oriented; has intellectual technology support and digital platform; is in a digital format; combines information resources and tools in relationship/communication/cooperation by connectedness, and also it is the dynamic face of the digital culture in time and space independence. Resolved with the study is that the digital libraries are active and effective in the formation of global knowing and/or mass wisdom in the process of digital culture.

  16. Neutron activation analysis applied to the determination of selenium in bovine plasma

    International Nuclear Information System (INIS)

    Hevia, Sonia E.; Resnizky, Sara M.; Gil, Susana B.; Pawlak, Eva

    1999-01-01

    The procedure used to determine selenium in bovine plasma by neutron irradiation of the samples, followed by a radiochemical separation, is described. This procedure allows the direct determination of the value of the selenium plasmatic level, instead of the indirect conventional method that determines the blood glutathion peroxidase enzyme, as an indicator of the selenium content in the blood. (author)

  17. Preventing Electromagnetic Pulse Irradiation Damage on Testis Using Selenium-rich Cordyceps Fungi. A Preclinical Study in Young Male Mice.

    Science.gov (United States)

    Miao, Xia; Wang, Yafeng; Lang, Haiyang; Lin, Yanyun; Guo, Qiyan; Yang, Mingjuan; Guo, Juan; Zhang, Yanjun; Zhang, Jie; Liu, Junye; Liu, Yaning; Zeng, Lihua; Guo, Guozhen

    2017-02-01

    Networked 21st century society, globalization, and communications technologies are paralleled by the rise of electromagnetic energy intensity in our environments and the growing pressure of the environtome on human biology and health. The latter is the entire complement of environmental factors, including the electromagnetic energy and the technologies that generate them, enacting on the digital citizen in the new century. Electromagnetic pulse (EMP) irradiation might have serious damaging effects not only on electronic equipment but also in the whole organism and reproductive health, through nonthermal effects and oxidative stress. We sought to determine whether EMP exposure (1) induces biological damage on reproductive health and (2) the extent to which selenium-rich Cordyceps fungi (daily coadministration) offer protection on the testicles and spermatozoa. In a preclinical randomized study, 3-week-old male BALB/c mice were repeatedly exposed to EMP (peak intensity 200 kV/m, pulse edge 3.5 ns, pulse width 15 ns, 0.1 Hz, and 400 pulses/day) 5 days per week for four consecutive weeks, with or without coadministration of daily selenium-rich Cordyceps fungi (100 mg/kg). Testicular index and spermatozoa formation were measured at baseline and 1, 7, 14, 28, and 60 day time points after EMP exposure. The group without Cordyceps cotreatment displayed decreased spermatozoa formation, shrunk seminiferous tubule diameters, and diminished antioxidative capacity at 28 and 60 days after exposure (p digital citizenship.

  18. Nanosized Selenium: A Novel Platform Technology to Prevent Bacterial Infections

    Science.gov (United States)

    Wang, Qi

    As an important category of bacterial infections, healthcare-associated infections (HAIs) are considered an increasing threat to the safety and health of patients worldwide. HAIs lead to extended hospital stays, contribute to increased medical costs, and are a significant cause of morbidity and mortality. In the United States, infections encountered in the hospital or a health care facility affect more than 1.7 million patients, cost 35.7 billion to 45 billion, and contribute to 88,000 deaths in hospitals annually. The most conventional and widely accepted method to fight against bacterial infections is using antibiotics. However, because of the widespread and sometimes inappropriate use of antibiotics, many strains of bacteria have rapidly developed antibiotic resistance. Those new, stronger bacteria pose serious, worldwide threats to public health and welfare. In 2014, the World Health Organization (WHO) reported antibiotic resistance as a global serious threat that is no longer a prediction for the future but is now reality. It has the potential to affect anyone, of any age, in any country. The most effective strategy to prevent antibiotic resistance is minimizing the use of antibiotics. In recent years, nanomaterials have been investigated as one of the potential substitutes of antibiotics. As a result of their vastly increased ratio of surface area to volume, nanomaterials will likely exert a stronger interaction with bacteria which may affect bacterial growth and propagation. A major concern of most existing antibacterial nanomaterials, like silver nanoparticles, is their potential toxicity. But selenium is a non-metallic material and a required nutrition for the human body, which is recommended by the FDA at a 53 to 60 μg daily intake. Nanosized selenium is considered to be healthier and less toxic compared with many metal-based nanomaterials due to the generation of reactive oxygen species from metals, especially heavy metals. Therefore, the objectives of

  19. Short range order in amorphous polycondensates

    Energy Technology Data Exchange (ETDEWEB)

    Lamers, C.; Richter, D.; Schweika, W. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung; Batoulis, J.; Sommer, K. [Bayer AG, Leverkusen (Germany); Cable, J.W. [Oak Ridge National Lab., TN (United States); Shapiro, S.M. [Brookhaven National Lab., Upton, NY (United States)

    1992-12-01

    The static coherent structure factors S(Q) of the polymer glass Bisphenol-A-Polycarbonate and its chemical variation Bisphenol-A- Polyctherkctone- both in differently deuterated versions- have been measured by spin polarized neutron scattering. The method of spin polarization analysis provided an experimental separation of coherent and incoherent scattering and a reliable intensity calibration. Results are compared to structure factors calculated for model structures which were obtained by ``amorphous cell`` computer simulations. In general reasonable agreement is found between experiment and simulation; however, certain discrepancies hint at an insufficient structural relaxation in the amorphous cell method. 15 refs, 1 fig, 1 tab.

  20. Ion bombardment and disorder in amorphous silicon

    International Nuclear Information System (INIS)

    Sidhu, L.S.; Gaspari, F.; Zukotynski, S.

    1997-01-01

    The effect of ion bombardment during growth on the structural and optical properties of amorphous silicon are presented. Two series of films were deposited under electrically grounded and positively biased substrate conditions. The biased samples displayed lower growth rates and increased hydrogen content relative to grounded counterparts. The film structure was examined using Raman spectroscopy. The transverse optic like phonon band position was used as a parameter to characterize network order. Biased samples displayed an increased order of the amorphous network relative to grounded samples. Furthermore, biased samples exhibited a larger optical gap. These results are correlated and attributed to reduced ion bombardment effects

  1. Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices

    OpenAIRE

    Schriver, Maria Christine

    2012-01-01

    A novel solar cell architecture made completely from the earth abundant elements silicon and carbon has been developed. Hydrogenated amorphous silicon (aSi:H), rather than crystalline silicon, is used as the active material due to its high absorption through a direct band gap of 1.7eV, well matched to the solar spectrum to ensure the possibility of improved cells in this architecture with higher efficiencies. The cells employ a Schottky barrier design wherein the amorphous silicon absorber la...

  2. Irradiation induced crystalline to amorphous transition

    International Nuclear Information System (INIS)

    Bourgoin, J.

    1980-01-01

    Irradiation of a crystalline solid with energetic heavy particles results in cascades of defects which, with increasing dose, overlap and form a continuous disordered layer. In semiconductors the physical properties of such disordered layers are found to be similar to those of amorphous layers produced by evaporation. It is shown in the case of silicon, that the transition from a disordered crystalline (X) layer to an amorphous (α) layer occurs when the Gibbs energy of the X phase and of the defects it contains becomes larger than the Gibbs energy of the α phase. (author)

  3. Effect of image quality on calcification detection in digital mammography

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C. [National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom); Jarvis Breast Screening and Diagnostic Centre, Guildford GU1 1LJ (United Kingdom); Department of Radiology, St. George' s Healthcare NHS Trust, Tooting, London SW17 0QT (United Kingdom); Cambridge Breast Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, United Kingdom and NIHR Cambridge Biomedical Research Centre, Cambridge CB2 0QQ (United Kingdom); Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15210 (United States); National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2012-06-15

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  4. Effect of image quality on calcification detection in digital mammography

    Science.gov (United States)

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-01-01

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  5. Effect of image quality on calcification detection in digital mammography.

    Science.gov (United States)

    Warren, Lucy M; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M; Wallis, Matthew G; Chakraborty, Dev P; Dance, David R; Bosmans, Hilde; Young, Kenneth C

    2012-06-01

    This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from

  6. Effect of image quality on calcification detection in digital mammography

    International Nuclear Information System (INIS)

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-01-01

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  7. Serum selenium and zinc levels in critically ill surgical patients.

    Science.gov (United States)

    Jang, Ji Young; Shim, Hongjin; Lee, Seung Hwan; Lee, Jae Gil

    2014-04-01

    The authors designed this study to determine how serum selenium and zinc affect the outcomes of critically ill surgical patients. The medical records of 162 patients admitted to a surgical intensive care unit (ICU) from October 2010 to July 2012 and managed for more than 3 days were retrospectively investigated. Overall, the mean patient age was 61.2 ± 15.0 years, and the median ICU stay was 5 (3-115) days. The mean Acute Physiologic and Chronic Health Evaluation II score was 18.0 ± 8.0. Eighteen (11.1%) of the study subjects died in ICU. mean selenium levels were 83.5 ± 23.8 ng/dL in the survivor group and 83.3 ± 29.6 ng/dL in the nonsurvivor group, and corresponding mean zinc levels were 46.3 ± 21.7 and 65.6 ± 41.6 μg/dL, respectively. Mean selenium concentrations were significantly different in patients with and without shock (77.9 ± 25.4 and 87.2 ± 23.1 ng/dL, P = .017). Furthermore, mean serum selenium was lower in patients with sepsis than in traumatic or simply postoperative patients (P selenium and zinc levels on critically ill surgical patients, a large-scale prospective study is needed. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

  8. AN ANALYTICAL METHOD FOR CHEMICAL SPECIATION OF SELENIUM IN SOIL

    Directory of Open Access Journals (Sweden)

    Constantin Luca

    2010-10-01

    Full Text Available Selenium is an essential microelement, sometimes redoubtable, through its beneficial role - risk depending on its concentration in the food chain, at low dose is an important nutrient in the life of humans and animals, contrary at high doses, it becomes toxic. Selenium may be find itself in the environment (soil, sediment, water in many forms (oxidized, reduced, organometallic which determine their mobility and toxicity. Determination of chemical speciation (identification of different chemical forms provides much more complete information for a better understanding of the behavior and the potential impact on the environment. In this work we present the results of methodological research on the extraction of sequential forms of selenium in the soil and the coupling of analytical methods capable of identifying very small amounts of selenium in soils An efficient scheme of sequential extractions forms of selenium (SES consisting in atomic absorption spectrometry coupled with hydride generation (HGAAS has been developed into five experimental steps, detailed in the paper. This operational scheme has been applied to the analysis of chemical speciation in the following areas: the Bărăgan Plain and Central Dobrogea of Romania.

  9. [Plasma selenium and peripartum cardiomyopathy in Bamako, Mali].

    Science.gov (United States)

    Cénac, A; Touré, K; Diarra, M B; Sergeant, C; Jobic, Y; Sanogo, K; Dembele, M; Fayol, V; Simonoff, M

    2004-01-01

    Peripartum heart failure due to unexplained dilated cardiomyopathy is a common disorder as Savannak-Sahelian Africa. One of the many suspected risk factors identified is selenium deficiency. The purpose of this study was to measure plasma selenium levels in patients with peripartum heart failure due to cardiomyopathy in Bamako, Republic of Mali and compare data with healthy Sahalian women with the same obstetrical status. Plasma selenium was measured in a patient group consisting of 28 Malian women presenting peripartum heart failure and in a control group of 28 healthy breast-feeding Nigerien women of comparable age. The criteria for matching the two groups was parity (similar number of deliveries) since multiparity is a risk factor for peripartum cardiomyopathy. The Wilcoxon test (nonparametric) was used to compare the 2 groups considering up value < 0.05 as significant. Plasma selenium was significantly lower in patients from Mali than in controls from Niger (65 +/- 17 ng/ml vs. 78 +/- 17 ng/ml, p = 0.01). The results of this study showing lower plasma selenium in Bamako patients with peripartum cardiomyopathy than in a matching healthy control population confirms the previous data from the Niamey study.

  10. Hypercholesterolemia and apolipoprotein B expression: Regulation by selenium status

    Directory of Open Access Journals (Sweden)

    Bansal Mohinder P

    2005-11-01

    Full Text Available Abstract Background Apolipoprotein B (apoB contains ligand-binding domain for the binding of LDL to LDL-R site, which enables the removal of LDL from circulation. Our recent data showed that selenium (Se is involved in the lipid metabolism. The present study was aimed to understand the effect of Se deficiency (0.02 ppm and selenium supplementation (1 ppm on apoB expression in liver during hypercholesterolemia in male Sprague Dawley rats. Animals were fed with control and high cholesterol diet (2% for 1 and 2 months. ApoB levels by ELISA and protein expression by western blot was done. Hepatic LDL receptor (LDL-R activity (in vivo and mRNA expression by RT-PCR was monitored. Results In selenium deficiency and on high cholesterol diet (HCD feeding apoB levels increased and LDL-R expression decreased significantly after 2 months. On 1 ppm selenium supplementation apoB expression significantly decreased and LDL-R expression increased after 2 months. But after one month of treatment there was no significant change observed in apoB and LDL-R expression. Conclusion So the present study demonstrates that Se deficiency leads to up regulation of apoB expression during experimental hypercholesterolemia. Selenium supplementation upto 1 ppm leads to downregulation of apoB expression. Further, this study will highlight the nutritional value of Se supplementation in lipid metabolism.

  11. Digital Tectonics

    DEFF Research Database (Denmark)

    Christiansen, Karl; Borup, Ruben; Søndergaard, Asbjørn

    2014-01-01

    Digital Tectonics treats the architectonical possibilities in digital generation of form and production. The publication is the first volume of a series, in which aspects of the strategic focus areas of the Aarhus School of Architecture will be disseminated.......Digital Tectonics treats the architectonical possibilities in digital generation of form and production. The publication is the first volume of a series, in which aspects of the strategic focus areas of the Aarhus School of Architecture will be disseminated....

  12. Digital skrivedidaktik

    DEFF Research Database (Denmark)

    Digital skrivedidaktik består af to dele. Første del præsenterer teori om skrivekompetence og digital skrivning. Digital skrivning er karakteriseret ved at tekster skrives på computer og med digitale værktøjer, hvilket ændrer skrivningens traditionelle praksis, produkt og processer. Hvad er digital...... om elevens skriveproces) og Blogskrivning (der styrker eleverne i at bruge blogs i undervisningen)....

  13. Plant selenium hyperaccumulation- Ecological effects and potential implications for selenium cycling and community structure.

    Science.gov (United States)

    Reynolds, R Jason B; Pilon-Smits, Elizabeth A H

    2018-04-25

    Selenium (Se) hyperaccumulation occurs in ~50 plant taxa native to seleniferous soils in Western USA. Hyperaccumulator tissue Se levels, 1000-15,000 mg/kg dry weight, are typically 100 times higher than surrounding vegetation. Relative to other species, hyperaccumulators also transform Se more into organic forms. We review abiotic and biotic factors influencing soil Se distribution and bioavailability, soil being the source of the Se in hyperaccumulators. Next, we summarize the fate of Se in plants, particularly hyperaccumulators. We then extensively review the impact of plant Se accumulation on ecological interactions. Finally, we discuss the potential impact of Se hyperaccumulators on local community composition and Se cycling. Selenium (hyper)accumulation offers ecological advantages: protection from herbivores and pathogens and competitive advantage over other plants. The extreme Se levels in and around hyperaccumulators create a toxic environment for Se-sensitive ecological partners, while offering a niche for Se-resistant partners. Through these dual effects, hyperaccumulators may influence species composition in their local environment, as well as Se cycling. The implied effects of Se hyperaccumulation on community assembly and local Se cycling warrant further investigations into the contribution of hyperaccumulators and general terrestrial vegetation to global Se cycling and may serve as a case study for how trace elements influence ecological processes. Furthermore, understanding ecological implications of plant Se accumulation are vital for safe implementation of biofortification and phytoremediation, technologies increasingly implemented to battle Se deficiency and toxicity. Copyright © 2018. Published by Elsevier B.V.

  14. Removal of colloidal biogenic selenium from wastewater.

    Science.gov (United States)

    Staicu, Lucian C; van Hullebusch, Eric D; Oturan, Mehmet A; Ackerson, Christopher J; Lens, Piet N L

    2015-04-01

    Biogenic selenium, Se(0), has colloidal properties and thus poses solid-liquid separation problems, such as poor settling and membrane fouling. The separation of Se(0) from the bulk liquid was assessed by centrifugation, filtration, and coagulation-flocculation. Se(0) particles produced by an anaerobic granular sludge are normally distributed, ranging from 50 nm to 250 nm, with an average size of 166±29 nm and a polydispersity index of 0.18. Due to its nanosize range and protein coating-associated negative zeta potential (-15 mV to -23 mV) between pH 2 and 12, biogenic Se(0) exhibits colloidal properties, hampering its removal from suspension. Centrifugation at different centrifugal speeds achieved 22±3% (1500 rpm), 73±2% (3000 rpm) and 91±2% (4500 rpm) removal. Separation by filtration through 0.45 μm filters resulted in 87±1% Se(0) removal. Ferric chloride and aluminum sulfate were used as coagulants in coagulation-flocculation experiments. Aluminum sulfate achieved the highest turbidity removal (92±2%) at a dose of 10(-3) M, whereas ferric chloride achieved a maximum turbidity removal efficiency of only 43±4% at 2.7×10(-4) M. Charge repression plays a minor role in particle neutralization. The sediment volume resulting from Al2(SO3)4 treatment is three times larger than that produced by FeCl3. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. DIGITAL FORGERY

    OpenAIRE

    Sarhan M. Musa1

    2017-01-01

    Forgery is the criminal act that provides misleading information about a product or service. It is the process of making, adapting, or imitating documents or objects with the intent to deceive. Digital forgery (or digital tampering) is the process of manipulating documents or images for the intent of financial, social or political gain. This paper provides a brief introduction to the digital forgery.

  16. Digital Citizenship

    Science.gov (United States)

    Isman, Aytekin; Canan Gungoren, Ozlem

    2014-01-01

    Era in which we live is known and referred as digital age.In this age technology is rapidly changed and developed. In light of these technological advances in 21st century, schools have the responsibility of training "digital citizen" as well as a good citizen. Digital citizens must have extensive skills, knowledge, Internet and …

  17. Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors

    Directory of Open Access Journals (Sweden)

    Karim S. Karim

    2011-05-01

    Full Text Available In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs. We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE. Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the

  18. Investigation of the selenium metabolism in cancer cell lines

    DEFF Research Database (Denmark)

    Lunøe, Kristoffer; Gabel-Jensen, Charlotte; Stürup, Stefan

    2011-01-01

    incubated with cells for 24 h and the induction of cell death was measured using flow cytometry. The amounts of total selenium in cell medium, cell lysate and the insoluble fractions was determined by ICP-MS. Speciation analysis of cellular fractions was performed by reversed phase, anion exchange and size......The aim of this work was to compare different selenium species for their ability to induce cell death in different cancer cell lines, while investigating the underlying chemistry by speciation analysis. A prostate cancer cell line (PC-3), a colon cancer cell line (HT-29) and a leukaemia cell line...... (Jurkat E6-1) were incubated with five selenium compounds representing inorganic as well as organic Se compounds in different oxidation states. Selenomethionine (SeMet), Se-methylselenocysteine (MeSeCys), methylseleninic acid (MeSeA), selenite and selenate in the concentration range 5-100 mu M were...

  19. Chemopreventive functional food through selenium biofortification of cauliflower plants

    Directory of Open Access Journals (Sweden)

    Anca Oancea

    2016-03-01

    Full Text Available The aim of this work was to develop a biotechnological approach for production of cauliflower as safe functional food, with an optimal content of chemopreventive compounds, by a protective biofortification, through selenium application together with betaine and spraying adjuvants. In the control and treated cauliflower plants we determined the amount of total selenium, glucosinolates (sulforaphane and SAH (S-Adenosyl-homocysteine. We also assayed the chemopreventive effects of compounds formed in the treated cruciferous plants through in vitro tests, using human colorectal tumor cell line (CaCo2. Extracts of plants treated with selenium applied together with betaine and spraying adjuvant were significantly more active on reduction of tumoral cell viability than the extract of control plants. Cauliflower plants, obtained after our treatments for protective biofortification, were used to feed rabbits, for 10 days. The ingestion of biofortified cauliflower did not modify the hematological and biochemical parameters on the laboratory animals.

  20. Deposition of selenium coatings on beryllium foils. Revision 1

    International Nuclear Information System (INIS)

    Erikson, E.D.; Tassano, P.L.; Reiss, R.H.; Griggs, G.E.

    1984-01-01

    A technique for preparing selenium films on 50.8 micrometers thick beryllium foils is described. The selenium was deposited in vacuum from a resistance heated evaporation source. A water-cooled enclosure was used to minimize contamination of the vacuum system and to reduce the exposure of personnel to toxic and obnoxious materials. Profilometry measurements of the coatings indicated selenium thicknesses of 5.5, 12.9, 37.5, 49.8 and 74.5 micrometers. The control of deposition rate and of coating thickness was facilitated using a commercially available closed-loop programmable deposition controller. The x-ray transmission of the coated substrates was measured using a tritiated zirconium source. The transmissivities of the film/substrate combination are presented for the range of energies from 4 to 20 keV

  1. [Studies on the hydroxyl free radical-scavenging effect of combined selenium and germanium].

    Science.gov (United States)

    Wu, Z; Chen, X; Yang, K; Xia, T

    2001-07-01

    The effect of selenium, carboxyethyl-germanium sesquioxide (Ge-132) and the combination of selenium and Ge-132 on the production of hydroxyl free radical in liver microsomes of rats treated with Fe2SO4-NADPH system was studied with electron spin resonance technique (ESR). The results showed that the production of hydroxyl free radical was decreased significantly by adding selenium, Ge-132 and combined selenium and Ge-132, indicating a direct scavenging effect on hydroxyl free radical. It was also observed a enhanced scavenging effect at the low concentration of combined selenium and Ge-132.

  2. Amorphization of metals by ion implantation and ion beam mixing

    International Nuclear Information System (INIS)

    Rauschenbach, B.; Heera, V.

    1988-01-01

    Amorphous metallic systems can be formed either by high-fluence ion implantation of glassforming species or by irradiation of layered metal systems with inert gas ions. Both techniques and experimental examples are presented. Empirical rules are discussed which predict whether a given system can be transformed into an amorphous phase. Influence of temperature, implantation dose and pre-existing crystalline metal composition on amorphization is considered. Examples are given of the implantation induced amorphous structure, recrystallization and formation of quasicrystalline structures. (author)

  3. Dynamics of hydrogen in hydrogenated amorphous silicon

    Indian Academy of Sciences (India)

    weak (strained) Si–Si bond thereby apparently enhancing the hydrogen diffusion and increasing the light-induced dangling bonds. Keywords. Hydrogenated amorphous silicon; metastable electronic states; hydrogen diffusion. PACS Nos 61.43.Dq; 66.30.-h; 71.23.Cq. 1. Introduction. Hydrogen passivation of dangling bonds ...

  4. Characterization of amorphous hydrogenated carbon films ...

    Indian Academy of Sciences (India)

    Amorphous hydrogenated carbon films (-C:H) on -type (100) silicon wafers were prepared with a middle frequency pulsed unbalanced magnetron sputtering technique (MFPUMST) at different ratios of methane–argon gases. The band characteristics, mechanical properties as well as refractive index were measured by ...

  5. Characterization of amorphous hydrogenated carbon films ...

    Indian Academy of Sciences (India)

    †Key Laboratory of Radiation and Technology of Education Ministry of China, Institute of Nuclear Science and. Technology, Sichuan University, Chengdu 610064, P. R. China. MS received 14 March 2011; revised 29 October 2011. Abstract. Amorphous hydrogenated carbon films (a-C:H) on p-type (100) silicon wafers were ...

  6. Unusual photoanisotropic alignment in amorphous azobenzene polymers

    DEFF Research Database (Denmark)

    Ramanujam, P.S.

    2015-01-01

    It is well known that irradiation of azobenzene polymer films between 490 and 530nm results in alignment of molecules perpendicular to the polarization of the incident beam. I have recently found that irradiation of amorphous azobenzene polymers with linearly polarized light at wavelengths between...

  7. Compaction of amorphous iron–boron powder

    DEFF Research Database (Denmark)

    Hendriksen, Peter Vang; Mørup, Steen; Koch, Christian

    1993-01-01

    report on attempts to compact amorphous iron–boron particles prepared by chemical reduction of Fe(II) ions in aqueous solution by NaBH4 (Ref. 2). The particles prepared in this way are pyrophoric, but can be passivated. The small particle size (10–100 nm), characteristic of this preparation technique...

  8. Trap level spectroscopy in amorphous semiconductors

    CERN Document Server

    Mikla, Victor V

    2010-01-01

    Although amorphous semiconductors have been studied for over four decades, many of their properties are not fully understood. This book discusses not only the most common spectroscopic techniques but also describes their advantages and disadvantages.Provides information on the most used spectroscopic techniquesDiscusses the advantages and disadvantages of each technique

  9. Film adhesion in amorphous silicon solar cells

    Indian Academy of Sciences (India)

    TECS

    Abstract. A major issue encountered during fabrication of triple junction a-Si solar cells on polyimide sub- strates is the adhesion of the solar cell thin films to the substrates. Here, we present our study of film adhesion in amorphous silicon solar cells made on different polyimide substrates (Kapton VN, Upilex-S and ...

  10. Structural morphology of amorphous conducting carbon film

    Indian Academy of Sciences (India)

    Amorphous conducting carbon films deposited over quartz substrates were analysed using X-ray diffraction and AFM technique. X-ray diffraction data reveal disorder and roughness in the plane of graphene sheet as compared to that of graphite. This roughness increases with decrease in preparation temperature. The AFM ...

  11. Film adhesion in amorphous silicon solar cells

    Indian Academy of Sciences (India)

    A major issue encountered during fabrication of triple junction -Si solar cells on polyimide substrates is the adhesion of the solar cell thin films to the substrates. Here, we present our study of film adhesion in amorphous silicon solar cells made on different polyimide substrates (Kapton VN, Upilex-S and Gouldflex), and the ...

  12. Characterization of amorphous and nanocrystalline carbon films

    International Nuclear Information System (INIS)

    Chu, Paul K.; Li Liuhe

    2006-01-01

    Amorphous and nanocrystalline carbon films possess special chemical and physical properties such as high chemical inertness, diamond-like properties, and favorable tribological proprieties. The materials usually consist of graphite and diamond microstructures and thus possess properties that lie between the two. Amorphous and nanocrystalline carbon films can exist in different kinds of matrices and are usually doped with a large amount of hydrogen. Thus, carbon films can be classified as polymer-like, diamond-like, or graphite-like based on the main binding framework. In order to characterize the structure, either direct bonding characterization methods or the indirect bonding characterization methods are employed. Examples of techniques utilized to identify the chemical bonds and microstructure of amorphous and nanocrystalline carbon films include optical characterization methods such as Raman spectroscopy, Ultra-violet (UV) Raman spectroscopy, and infrared spectroscopy, electron spectroscopic and microscopic methods such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, transmission electron microscopy, and electron energy loss spectroscopy, surface morphology characterization techniques such as scanning probe microscopy (SPM) as well as other characterization methods such as X-ray reflectivity and nuclear magnetic resonance. In this review, the structures of various types of amorphous carbon films and common characterization techniques are described

  13. Dynamics of hydrogen in hydrogenated amorphous silicon

    Indian Academy of Sciences (India)

    c0, c being the instantaneous concentration at a local point and c0, the average concentration of hydrogen in the hydrogenated amorphous silicon. If the system is both incompressible and isotropic, the change in Helmholtz free energy due to fluctuations in the local concentration of hydrogen is given as. 122. Pramana – J.

  14. Radiative recombination of excitons in amorphous semiconductors

    International Nuclear Information System (INIS)

    Singh, Jai

    2005-01-01

    A theory for calculating the radiative lifetime of excitons in amorphous semiconductors is presented. Four possibilities of excitonic radiative recombination are considered and the corresponding rates are derived at thermal equilibrium. The radiative lifetime is calculated from the inverse of the maximum rate for all the four possibilities. Results agree very well with experiments

  15. Neutron diffraction studies of amorphous solids

    International Nuclear Information System (INIS)

    Wright, A.C.

    1983-01-01

    A brief survey is presented of the role of neutron diffraction in structural studies of amorphous solids. The inherent limitations of the diffraction technique are discussed, together with modern instrumentation and methods for separating individual component correlation functions. An introduction is given to the use of modelling and the extraction of structural parameters from experimental data. (author)

  16. Amorphous calcium carbonate particles form coral skeletons

    Science.gov (United States)

    Mass, Tali; Giuffre, Anthony J.; Sun, Chang-Yu; Stifler, Cayla A.; Frazier, Matthew J.; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V.; Marcus, Matthew A.; Gilbert, Pupa U. P. A.

    2017-09-01

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO3). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO2 increases, such as the Paleocene-Eocene Thermal Maximum that occurred 56 Mya.

  17. Amorphous track models: A numerical comparison study

    DEFF Research Database (Denmark)

    Greilich, Steffen; Grzanka, L.; Bassler, N.

    2010-01-01

    We present an open-source code library for amorphous track modelling which is suppose to faciliate the application and numerical comparability as well as serve as a frame-work for the implementation of new models. We show an example of using the library indicating the choice of submodels has a si...

  18. The Electronic Structure of Amorphous Carbon Nanodots.

    Science.gov (United States)

    Margraf, Johannes T; Strauss, Volker; Guldi, Dirk M; Clark, Timothy

    2015-06-18

    We have studied hydrogen-passivated amorphous carbon nanostructures with semiempirical molecular orbital theory in order to provide an understanding of the factors that affect their electronic properties. Amorphous structures were first constructed using periodic calculations in a melt/quench protocol. Pure periodic amorphous carbon structures and their counterparts doped with nitrogen and/or oxygen feature large electronic band gaps. Surprisingly, descriptors such as the elemental composition and the number of sp(3)-atoms only influence the electronic structure weakly. Instead, the exact topology of the sp(2)-network in terms of effective conjugation defines the band gap. Amorphous carbon nanodots of different structures and sizes were cut out of the periodic structures. Our calculations predict the occurrence of localized electronic surface states, which give rise to interesting effects such as amphoteric reactivity and predicted optical band gaps in the near-UV/visible range. Optical and electronic gaps display a dependence on particle size similar to that of inorganic colloidal quantum dots.

  19. Plasma deposition of amorphous metal alloys

    Science.gov (United States)

    Hays, Auda K.

    1986-01-01

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  20. The Effect on Selenium Concentrations of a Randomized Intervention with Fish and Mussels in a Population with Relatively Low Habitual Dietary Selenium Intake

    DEFF Research Database (Denmark)

    Outzen, Malene; Tjønneland, Anne; Larsen, Erik Huusfeldt

    2015-01-01

    /week for 26 weeks (similar to 50 mu g selenium/day). Controls received no intervention. Non-fasting blood samples were taken and whole blood selenium was determined using inductively coupled plasma-mass spectrometry (ICP-MS), and plasma selenoprotein P (SelP) was determined by high performance liquid......Selenium status of the Danish population is below that assumed optimal for the suggested protective effects against chronic diseases, including certain cancers. Fish and shellfish are important dietary sources of selenium in Denmark. We investigated the effect of increased fish and mussel intake...... on selenium blood concentrations in a population with relatively low habitual dietary selenium intake. We randomly assigned 102 healthy men and women (all non-smokers) aged 48-76 years to an intervention group (n = 51) or a control group (n = 51). Intervention participants received 1000 g fish and mussels...

  1. Reduction of selenite to elemental selenium nanoparticles by activated sludge.

    Science.gov (United States)

    Jain, Rohan; Matassa, Silvio; Singh, Satyendra; van Hullebusch, Eric D; Esposito, Giovanni; Lens, Piet N L

    2016-01-01

    Total selenium removal by the activated sludge process, where selenite is reduced to colloidal elemental selenium nanoparticles (BioSeNPs) that remain entrapped in the activated sludge flocs, was studied. Total selenium removal efficiencies with glucose as electron donor (2.0 g chemical oxygen demand (COD) L(-1)) at neutral pH and 30 °C gave 2.9 and 6.8 times higher removal efficiencies as compared to the electron donors lactate and acetate, respectively. Total selenium removal efficiencies of 79 (±3) and 86 (±1) % were achieved in shake flasks and fed batch reactors, respectively, at dissolved oxygen (DO) concentrations above 4.0 mg L(-1) and 30 °C when fed with 172 mg L(-1) (1 mM) Na2SeO3 and 2.0 g L(-1) COD of glucose. Continuously operated reactors operating at neutral pH, 30 °C and a DO >3 mg L(-1) removed 33.98 and 36.65 mg of total selenium per gram of total suspended solids (TSS) at TSS concentrations of 1.3 and 3.0 g L(-1), respectively. However, selenite toxicity to the activated sludge led to failure of a continuously operating activated sludge reactor at the applied loading rates. This suggests that a higher hydraulic retention time (HRT) or different reactor configurations need to be applied for selenium-removing activated sludge processes. Graphical Abstract Scheme representing the possible mechanisms of selenite reduction at high and low DO levels in the activated sludge process.

  2. Digital preservation

    CERN Document Server

    Deegan, Marilyn

    2013-01-01

    Digital preservation is an issue of huge importance to the library and information profession right now. With the widescale adoption of the internet and the rise of the world wide web, the world has been overwhelmed by digital information. Digital data is being produced on a massive scale by individuals and institutions: some of it is born, lives and dies only in digital form, and it is the potential death of this data, with its impact on the preservation of culture, that is the concern of this book. So how can information professionals try to remedy this? Digital preservation is a complex iss

  3. A study using neutron activation analysis of the short-term changes in the selenium content of blood components in human following supplementation with low doses of selenium

    International Nuclear Information System (INIS)

    McOrist, G.D.; Fardy, J.J.; Sleet, R.

    1992-01-01

    A study was undertaken to evaluate the short-term changes in the concentration of selenium in whole blood, plasma and erythrocytes following supplementation with low doses of four different selenium supplements. Fourteen volunteers took one of the supplements each day with breakfast or a period of six weeks. Two blood samples were taken each week during this time and selenium was determined on its components using neutron activation analysis via the 77m Se isotope. (author) 17 refs.; 6 figs

  4. Biochemical and biophysical characterization of the selenium-binding and reducing site in Arabidopsis thaliana homologue to mammals selenium-binding protein 1.

    Science.gov (United States)

    Schild, Florie; Kieffer-Jaquinod, Sylvie; Palencia, Andrés; Cobessi, David; Sarret, Géraldine; Zubieta, Chloé; Jourdain, Agnès; Dumas, Renaud; Forge, Vincent; Testemale, Denis; Bourguignon, Jacques; Hugouvieux, Véronique

    2014-11-14

    The function of selenium-binding protein 1 (SBP1), present in almost all organisms, has not yet been established. In mammals, SBP1 is known to bind the essential element selenium but the binding site has not been identified. In addition, the SBP family has numerous potential metal-binding sites that may play a role in detoxification pathways in plants. In Arabidopsis thaliana, AtSBP1 over-expression increases tolerance to two toxic compounds for plants, selenium and cadmium, often found as soil pollutants. For a better understanding of AtSBP1 function in detoxification mechanisms, we investigated the chelating properties of the protein toward different ligands with a focus on selenium using biochemical and biophysical techniques. Thermal shift assays together with inductively coupled plasma mass spectrometry revealed that AtSBP1 binds selenium after incubation with selenite (SeO3(2-)) with a ligand to protein molar ratio of 1:1. Isothermal titration calorimetry confirmed the 1:1 stoichiometry and revealed an unexpectedly large value of binding enthalpy suggesting a covalent bond between selenium and AtSBP1. Titration of reduced Cys residues and comparative mass spectrometry on AtSBP1 and the purified selenium-AtSBP1 complex identified Cys(21) and Cys(22) as being responsible for the binding of one selenium. These results were validated by site-directed mutagenesis. Selenium K-edge x-ray absorption near edge spectroscopy performed on the selenium-AtSBP1 complex demonstrated that AtSBP1 reduced SeO3(2-) to form a R-S-Se(II)-S-R-type complex. The capacity of AtSBP1 to bind different metals and selenium is discussed with respect to the potential function of AtSBP1 in detoxification mechanisms and selenium metabolism. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Crystallization of biogenic hydrous amorphous silica

    Science.gov (United States)

    Kyono, A.; Yokooji, M.; Chiba, T.; Tamura, T.; Tuji, A.

    2017-12-01

    Diatom, Nitzschia cf. frustulum, collected from Lake Yogo, Siga prefecture, Japan was cultured in laboratory. Organic components of the diatom cell were removed by washing with acetone and sodium hypochlorite. The remaining frustules were studied by SEM-EDX, FTIR spectroscopy, and synchrotron X-ray diffraction. The results showed that the spindle-shaped morphology of diatom frustule was composed of hydrous amorphous silica. Pressure induced phase transformation of the diatom frustule was investigated by in situ Raman spectroscopic analysis. With exposure to 0.3 GPa at 100 oC, Raman band corresponding to quartz occurred at ν = 465 cm-1. In addition, Raman bands known as a characteristic Raman pattern of moganite was also observed at 501 cm-1. From the integral ratio of Raman bands, the moganite content in the probed area was estimated to be approximately 50 wt%. With the pressure and temperature effect, the initial morphology of diatom frustule was completely lost and totally changed to a characteristic spherical particle with a diameter of about 2 mm. With keeping the compression of 5.7 GPa at 100 oC, a Raman band assignable to coesite appeared at 538 cm-1. That is, with the compression and heating, the hydrous amorphous silica can be readily crystallized into quartz, moganite, and coesite. The first-principles calculations revealed that a disiloxane molecule stabilized in a trans configuration is twisted 60o and changed into the cis configuration with a close approach of water molecule. It is therefore a reasonable assumption that during crystallization of hydrous amorphous silica, the Si-O-Si bridging unit with the cis configuration would survive as a structural defect and then crystallized into moganite by keeping the geometry. This hypothesis is adaptable to the phase transformation from hydrous amorphous silica to coesite as well, because coesite has the four-membered rings and easily formed from the hydrous amorphous silica under high pressure and high

  6. The necessity of selenium substitution in total parenteral nutrition and artificial alimentation.

    Science.gov (United States)

    Gramm, H J; Kopf, A; Brätter, P

    1995-03-01

    For the trace element selenium, in contrast to zinc, iron, copper, chromium, manganese and iodine, there is still no clear official recommendation with regard to routine substitution in artificial nutrition. An overview of the manifestations of selenium deficiency in humans during the period 1979-1995 shows that nutritive deficiencies are exclusively TPN-induced or the result of severe malnutrition. The pathology of TPN-induced selenium deficiency and the analytic assessment of selenium status are described. Patients undergoing long-term parenteral nutrition or suffering from an increased loss of intestinal secretions have to be characterized as being especially at risk for clinical selenium deficiency. The relationship of the serum selenium kinetics in pediatric and adult patients to the depletion of body compartments during the course of short-term and prolonged TPN is discussed. Because of the importance of the selenoproteins, the regularly occurring depletion during selenium-free TPN and the borderline supply of selenium in Germany the routine substitution of selenium in TPN is strongly recommended. The pharmaceutical industry should be encouraged to develop a trace element solution that includes selenium, so that the nutritive requirement of patients on TPN can be satisfied. Adequate intravenous dosage recommendations are based on maintenance of glutathione peroxidase homeostasis. The routine supplementation dosage may not meet the selenium requirements of intensive care patients under conditions of increased metabolic demands on their anti-oxidative system.

  7. Selenium and Its Supplementation in Cardiovascular Disease—What do We Know?

    Science.gov (United States)

    Benstoem, Carina; Goetzenich, Andreas; Kraemer, Sandra; Borosch, Sebastian; Manzanares, William; Hardy, Gil; Stoppe, Christian

    2015-01-01

    The trace element selenium is of high importance for many of the body’s regulatory and metabolic functions. Balanced selenium levels are essential, whereas dysregulation can cause harm. A rapidly increasing number of studies characterizes the wide range of selenium dependent functions in the human body and elucidates the complex and multiple physiological and pathophysiological interactions of selenium and selenoproteins. For the majority of selenium dependent enzymes, several biological functions have already been identified, like regulation of the inflammatory response, antioxidant properties and the proliferation/differentiation of immune cells. Although the potential role of selenium in the development and progression of cardiovascular disease has been investigated for decades, both observational and interventional studies of selenium supplementation remain inconclusive and are considered in this review. This review covers current knowledge of the role of selenium and selenoproteins in the human body and its functional role in the cardiovascular system. The relationships between selenium intake/status and various health outcomes, in particular cardiomyopathy, myocardial ischemia/infarction and reperfusion injury are reviewed. We describe, in depth, selenium as a biomarker in coronary heart disease and highlight the significance of selenium supplementation for patients undergoing cardiac surgery. PMID:25923656

  8. Solution NMR structure of selenium-binding protein from Methanococcus vannielii.

    Science.gov (United States)

    Suzuki, Motoshi; Lee, Duck-Yeon; Inyamah, Nwakaego; Stadtman, Thressa C; Tjandra, Nico

    2008-09-19

    Selenium is an important nutrient. The lack of selenium will suppress expression of various enzymes that will lead to cell abnormality and diseases. However, high concentrations of free selenium are toxic to the cell because it adversely affects numerous cell metabolic pathways. In Methanococcus vannielii, selenium transport in the cell is established by the selenium-binding protein, SeBP. SeBP sequesters selenium during transport, thus regulating the level of free selenium in the cell, and delivers it specifically to the selenophosphate synthase enzyme. In solution, SeBP is an oligomer of 8.8-kDa subunits. It is a symmetric pentamer. The solution structure of SeBP was determined by NMR spectroscopy. Each subunit of SeBP is composed of an alpha-helix on top of a 4-stranded twisted beta-sheet. The stability of the five subunits stems mainly from hydrophobic interactions and supplemented by hydrogen bond interactions. The loop containing Cys(59) has been shown to be important for selenium binding, is flexible, and adopts multiple conformations. However, the cysteine accessibility is restricted in the structure, reducing the possibility of the binding of free selenium readily. Therefore, a different selenium precursor or other factors might be needed to facilitate opening of this loop to expose Cys(59) for selenium binding.

  9. Blood selenium content determination by X-ray fluorescence

    International Nuclear Information System (INIS)

    Mainardi, R.T.

    1987-01-01

    The presence of some elements in small amounts (traces) in the human body is of foremost importance for the prevention and treatment of several diseases. It has been recently shown that traces of selenium in blood are closely related to the occurrence of miotonic distrophy, a muscular disease that is affecting a significant percentage of the population. This work describes a simple procedure to determine selenium in human blood serum by energy dispersive X-ray fluorescence analysis. Final quantification is achieved through the addition of titanium as an internal standard. (Author) [es

  10. Theoretical predictions of arsenic and selenium species under atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Monahan-Pendergast, M.T.; Przybylek, M.; Lindblad, M.; Wilcox, J. [Worcester Polytechnic Institute, Worcester, MA (United States). Dept. of Chemical Engineering

    2008-03-15

    Thermochemical properties of arsenic and selenium species thought to be released into the atmosphere during the coal combustion were examined using ab initio methods. At various levels of theory, calculated geometries and vibrational frequencies of the species were compared with experimental data, where available. Through a comparison of equilibrium constants for a series of gaseous arsenic and selenium oxidation reactions involving OH and HO{sub 2}, five thermodynamically favored reactions were found. In addition, it was determined that all favored reactions were more likely to go to completion tinder tropospheric, rather than stratospheric, conditions.

  11. Megavoltage imaging with a large-area, flat-panel, amorphous silicon imager

    International Nuclear Information System (INIS)

    Antonuk, Larry E.; Yorkston, John; Huang Weidong; Sandler, Howard; Siewerdsen, Jeffrey H.; El-Mohri, Youcef

    1996-01-01

    Purpose: The creation of the first large-area, amorphous silicon megavoltage imager is reported. The imager is an engineering prototype built to serve as a stepping stone toward the creation of a future clinical prototype. The engineering prototype is described and various images demonstrating its properties are shown including the first reported patient image acquired with such an amorphous silicon imaging device. Specific limitations in the engineering prototype are reviewed and potential advantages of future, more optimized imagers of this type are presented. Methods and Materials: The imager is based on a two-dimensional, pixelated array containing amorphous silicon field-effect transistors and photodiode sensors which are deposited on a thin glass substrate. The array has a 512 x 560-pixel format and a pixel pitch of 450 μm giving an imaging area of ∼23 x 25 cm 2 . The array is used in conjunction with an overlying metal plate/phosphor screen converter as well as an electronic acquisition system. Images were acquired fluoroscopically using a megavoltage treatment machine. Results: Array and digitized film images of a variety of anthropomorphic phantoms and of a human subject are presented and compared. The information content of the array images generally appears to be at least as great as that of the digitized film images. Conclusion: Despite a variety of severe limitations in the engineering prototype, including many array defects, a relatively slow and noisy acquisition system, and the lack of a means to generate images in a radiographic manner, the prototype nevertheless generated clinically useful information. The general properties of these amorphous silicon arrays, along with the quality of the images provided by the engineering prototype, strongly suggest that such arrays could eventually form the basis of a new imaging technology for radiotherapy localization and verification. The development of a clinically useful prototype offering high

  12. Effect of irradiation on sod activity and selenium content in garlic

    International Nuclear Information System (INIS)

    Xu Weimin; Zheng Anjian; Yan Jianmin; Cao Qingsui; Wu Haihong; Cao Shifeng

    2006-01-01

    The effects of irradiation at 0.1 kGy, 1.0 kGy on SOD activity and the content of total selenium, inorganic selenium, organic selenium in garlic (Allium sativum L.) stored at 10 degree C or 25 degree C were investigated. The results indicated that irradiation treatment with 0.1 kGy, 1 kGy significantly slowed the reduction of SOD activities in garlic stored at 10 degree C or 25 degree C, while the treatment irradiation had no influence on the content of all kinds of selenium. But the garlic stored at 25 degree C had higher content of total selenium, inorganic selenium, organic selenium than that in garlic stored at 10 degree C. (authors)

  13. First-Principles Prediction of Densities of Amorphous Materials: The Case of Amorphous Silicon

    Science.gov (United States)

    Furukawa, Yoritaka; Matsushita, Yu-ichiro

    2018-02-01

    A novel approach to predict the atomic densities of amorphous materials is explored on the basis of Car-Parrinello molecular dynamics (CPMD) in density functional theory. Despite the determination of the atomic density of matter being crucial in understanding its physical properties, no first-principles method has ever been proposed for amorphous materials until now. We have extended the conventional method for crystalline materials in a natural manner and pointed out the importance of the canonical ensemble of the total energy in the determination of the atomic densities of amorphous materials. To take into account the canonical distribution of the total energy, we generate multiple amorphous structures with several different volumes by CPMD simulations and average the total energies at each volume. The density is then determined as the one that minimizes the averaged total energy. In this study, this approach is implemented for amorphous silicon (a-Si) to demonstrate its validity, and we have determined the density of a-Si to be 4.1% lower and its bulk modulus to be 28 GPa smaller than those of the crystal, which are in good agreement with experiments. We have also confirmed that generating samples through classical molecular dynamics simulations produces a comparable result. The findings suggest that the presented method is applicable to other amorphous systems, including those for which experimental knowledge is lacking.

  14. Selenium species determination in selenium-enriched pumpkin (Cucurbita pepo L.) seeds by HPLC-UV-HG-AFS.

    Science.gov (United States)

    Smrkolj, Polona; Stibilj, Vekoslava; Kreft, Ivan; Kapolna, Emese

    2005-12-01

    Pumpkins were treated by spraying the leaves in the flowering period with a water solution containing 1.5 mg Se per liter in the form of Na2SeO4. The average total selenium content of seeds was found to be 0.19 microg g(-1) in nontreated pumpkins and 1.1 microg g(-1) in exposed ones. For speciation analysis, enzymatic hydrolysis with different amounts of Protease XIV was carried out. Under optimal conditions of enzymatic hydrolysis, 90% of the total selenium was found in soluble forms. Separation of species was performed using HPLC on anion and cation exchange columns and for detection UVHG-AFS was applied. In enzymatic hydrolysis extracts, the main fraction of selenium was bound as selenomethionine (SeMet), representing on average of 81 +/- 8% of the total Se content in the sample.

  15. Dietary intake of selenium and serum selenium in patients with chronic hepatitis B, liver cirrhosis and acute-on-chronic liver failure

    Directory of Open Access Journals (Sweden)

    ZHAO Juan

    2015-07-01

    Full Text Available Objective To analyse dietary intake of selenium and serum selenium levels in patients with different types of chronic liver diseases, and to explore the relationship between selenium and severity of liver diseases. Methods Seventy-four patients admitted to Beijing YouAn Hospital from August 2008 to October 2014, as well as 16 healthy persons as healthy control (HC group, were recruited in this study. Based on liver disease types, these patients were divided into chronic hepatitis (CH group (n=23, liver cirrhosis (LC group (n=27, and acute-on-chronic liver failure (ACLF group (n=24. Dietary intake of selenium was calculated on admission by dietary assessment software, and serum selenium levels were measured by inductively coupled plasma-atomic emission spectroscopy. Comparison of continuous data between groups was made by one-way ANOVA; comparison of categorical data between groups was made by χ2 test; the correlation between variables was determined by Pearson correlation analysis. Results The dietary selenium intake in the HC group was 4545±18.10 μg. Compared with the HC group, the CH group, LC group, and ACLF group had insufficient dietary intake of selenium (37.69±11.30 μg, 32.65±13.55 μg, and 28.95±13.30 μg, respectively. Dietary selenium intake gradually decreased with the progression of liver disease. Compared with the HC group, the LC group and ACLF group had significantly lower dietary selenium intake (P=0.004 and 0.000, respectively. Serum selenium in the HC group was 0.17±0.04 μg/ml. Compared with the HC group, the CH group, LC group, and ACLF group had significantly lower serum selenium levels (0.12±0.05 μg/ml, P=0.007; 0.11±0.06 μg/ml, P=0.000; 0.13±0.05 μg/ml, P=0.015. Serum selenium in the LC group was reduced most among these groups. Furthermore, serum selenium was significantly associated with prealbumin level, white blood cell count, and platelet count (r=0.229, P=0.030; r=0.213, P=0.044; r=0.255, P=0

  16. Selenium speciation profiles in biofortified sangiovese wine.

    Science.gov (United States)

    Fontanella, Maria Chiara; D'Amato, Roberto; Regni, Luca; Proietti, Primo; Beone, Gian Maria; Businelli, Daniela

    2017-09-01

    Biofortification is an agronomic-based strategy, utilized by farmers, to produce selenium (Se)-enriched food products that may help reduce dietary deficiencies of Se occurring throughout susceptible regions of the world. The foliar exposure route application ensures a high efficiency of Se assimilation by the plant since it does not depend on root-to-shoot translocation. In this study we treated grapevines of Sangiovese variety in the pre-flowering period with sodium selenate (100mg Se L -1 ). Se content was measured in leaves, fruit at harvest time and in wine respectively in treated and not treated samples with ICP-MS. At harvest, a higher amount of Se in the treated leaves compared to untreated ones was found, 16.0±3.1mgkg -1 dry weight (dw) against 0.17±0.006mgkg -1 dw in the untreated ones. The treated grapes had a content of Se of 0.800±0.08mgkg -1 dw, while that untreated one 0.065±0.025mgkg -1 dw. Immediately after the malolactic fermentation, the wine obtained from treated and untreated vines had a Se content of 0.620±0.09mg Se L -1 and 0.024±0.010mg Se L -1 respectively. In our case the percentage of inorganic Se is 26% of the total Se in the untreated wine, while in Se enriched wine this percentage increase to 47.5% of the total Se. The Se(VI) was the inorganic chemical form more present in enriched wine, probably due to foliar application with selenate. Distributions of Se species suggested being careful to the choice of the enrichment solutions to promote a balanced distribution of different chemical forms, perhaps favouring the accumulation of organic forms. Copyright © 2016 Elsevier GmbH. All rights reserved.

  17. Selenium Speciation and Management in Wet FGD Systems

    Energy Technology Data Exchange (ETDEWEB)

    Searcy, K; Richardson, M; Blythe, G; Wallschlaeger, D; Chu, P; Dene, C

    2012-02-29

    This report discusses results from bench- and pilot-scale simulation tests conducted to determine the factors that impact selenium speciation and phase partitioning in wet FGD systems. The selenium chemistry in wet FGD systems is highly complex and not completely understood, thus extrapolation and scale-up of these results may be uncertain. Control of operating parameters and application of scrubber additives have successfully demonstrated the avoidance or decrease of selenite oxidation at the bench and pilot scale. Ongoing efforts to improve sample handling methods for selenium speciation measurements are also discussed. Bench-scale scrubber tests explored the impacts of oxidation air rate, trace metals, scrubber additives, and natural limestone on selenium speciation in synthetic and field-generated full-scale FGD liquors. The presence and concentration of redox-active chemical species as well as the oxidation air rate contribute to the oxidation-reduction potential (ORP) conditions in FGD scrubbers. Selenite oxidation to the undesirable selenate form increases with increasing ORP conditions, and decreases with decreasing ORP conditions. Solid-phase manganese [Mn(IV)] appeared to be the significant metal impacting the oxidation of selenite to selenate. Scrubber additives were tested for their ability to inhibit selenite oxidation. Although dibasic acid and other scrubber additives showed promise in early clear liquor (sodium based and without calcium solids) bench-scale tests, these additives did not show strong inhibition of selenite oxidation in tests with higher manganese concentrations and with slurries from full-scale wet FGD systems. In bench-tests with field liquors, addition of ferric chloride at a 250:1 iron-to-selenium mass ratio sorbed all incoming selenite to the solid phase, although addition of ferric salts had no impact on native selenate that already existed in the field slurry liquor sample. As ORP increases, selenite may oxidize to selenate more

  18. Amorphous Carbon: State of the Art - Proceedings of the 1st International Specialist Meeting on Amorphous Carbon (smac '97)

    Science.gov (United States)

    Silva, S. R. P.; Robertson, J.; Milne, W. I.; Amaratunga, G. A. J.

    1998-05-01

    The Table of Contents for the full book PDF is as follows: * Preface * GROWTH AND STRUCTURE * The Structure of Tetrahedral Amorphous Carbon * Growth of DLC Films and Related Structure and Properties * Deposition Mechanism of Diamond-Like Carbon * Relaxation of sp3 Bonds in Hydrogen Free Carbon Films During Growth * MODELLING * Correlations Between Microstructure and Electronic Properties in Amorphous Carbon Based Materials * Review of Monte Carlo Simulations of Diamondlike Amorphous Carbon: Bulk, Surface, and Interface Structural Properties * DEPOSITION * Preparation of Disordered Amorphous and Partially Ordered Nano Clustered Carbon Films by Arc Deposition: A Critical Review * Plasma Deposition of Diamond-Like Carbon in an ECR-RF Discharge * Deposition of Amorphous Hydrogenated Carbon-Nitrogen Films by PECVD Using Several Hydrocarbon / Nitrogen Containing Gas Mixtures * ELECTRONIC STRUCTURE * 'Defects' and Their Detection in a-C and a-C:H * Valence Band and Gap State Spectroscopy of Amorphous Carbon by Photoelectron Emission Techniques * Photoluminescence Spectroscopy: A Probe for Inhomogeneous Structure in Polymer-Like Amorphous Carbon * Raman Characterization of Amorphous and Nanocrystalline sp3 Bonded Structures * Ultraviolet Raman Spectroscopy of Tetrahedral Amorphous Carbon Thin Films * Excitation Energy Dependent Raman and Photoluminescence Spectra of Hydrogenated Amorphous Carbon * MECHANICAL PROPERTIES * Pulsed Laser Deposited a-C: Growth, Structure and Mechanical Properties * Mechanical Properties of Laser-Assisted Deposited Amorphous Carbon Films * Mechanical and Morphology Study on Tetrahedral Amorphous Carbon Films * Time-Dependent Changes in the Mechanical Properties of Diamond-Like Carbon Films * ELECTRONIC PROPERTIES * Electronic Transport in Amorphous Carbon * Electronic Properties of Undoped/Doped Tetrahedral Amorphous Carbon * The Inclusion of Graphitic Nanoparticles in Semiconducting Amorphous Carbon to Enhance Electronic Transport Properties

  19. Emerging trends in the stabilization of amorphous drugs.

    Science.gov (United States)

    Laitinen, Riikka; Löbmann, Korbinian; Strachan, Clare J; Grohganz, Holger; Rades, Thomas

    2013-08-30

    The number of active pharmaceutical substances having high therapeutic potential but low water solubility is constantly increasing, making it difficult to formulate these compounds as oral dosage forms. The solubility and dissolution rate, and thus potentially the bioavailability, of these poorly water-soluble drugs can be increased by the formation of stabilized amorphous forms. Currently, formulation as solid polymer dispersions is the preferred method to enhance drug dissolution and to stabilize the amorphous form of a drug. The purpose of this review is to highlight emerging alternative methods to amorphous polymer dispersions for stabilizing the amorphous form of drugs. First, an overview of the properties and stabilization mechanisms of amorphous forms is provided. Subsequently, formulation approaches such as the preparation of co-amorphous small-molecule mixtures and the use of mesoporous silicon and silica-based carriers are presented as potential means to increase the stability of amorphous pharmaceuticals. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Amorphous-crystalline transition in thermoelectric NbO2

    International Nuclear Information System (INIS)

    Music, Denis; Chen, Yen-Ting; Bliem, Pascal; Geyer, Richard W

    2015-01-01

    Density functional theory was employed to design enhanced amorphous NbO 2 thermoelectrics. The covalent-ionic nature of Nb–O bonding is identical in amorphous NbO 2 and its crystalline counterpart. However, the Anderson localisation occurs in amorphous NbO 2 , which may affect the transport properties. We calculate a multifold increase in the absolute Seebeck coefficient for the amorphous state. These predictions were critically appraised by measuring the Seebeck coefficient of sputtered amorphous and crystalline NbO 2 thin films with the identical short-range order. The first-order phase transition occurs at approximately 550 °C, but amorphous NbO 2 possesses enhanced transport properties at all temperatures. Amorphous NbO 2 , reaching  −173 μV K −1 , exhibits up to a 29% larger absolute Seebeck coefficient value, thereby validating the predictions. (paper)

  1. Digital mammography

    International Nuclear Information System (INIS)

    Bick, Ulrich; Diekmann, Felix

    2010-01-01

    This state-of-the-art reference book provides in-depth coverage of all aspects of digital mammography, including detector technology, image processing, computer-aided diagnosis, soft-copy reading, digital workflow, and PACS. Specific advantages and disadvantages of digital mammography in comparison to screen-film mammography are thoroughly discussed. By including authors from both North America and Europe, the book is able to outline variations in the use, acceptance, and quality assurance of digital mammography between the different countries and screening programs. Advanced imaging techniques and future developments such as contrast mammography and digital breast tomosynthesis are also covered in detail. All of the chapters are written by internationally recognized experts and contain numerous high-quality illustrations. This book will be of great interest both to clinicians who already use or are transitioning to digital mammography and to basic scientists working in the field. (orig.)

  2. Digital Signage

    OpenAIRE

    Fischer, Karl Peter

    2011-01-01

    Digital Signage for in-store advertising at gas stations/retail stores in Germany: A field study Digital Signage networks provide a novel means of advertising with the advantage of easily changeable and highly customizable animated content. Despite the potential and increasing use of these media empirical research is scarce. In a field study at 8 gas stations (with integrated convenience stores) we studied the effect of digital signage advertising on sales for different products and servi...

  3. Digital Forensics

    OpenAIRE

    Garfinkel, Simson L.

    2013-01-01

    A reprint from American Scientist the magazine of Sigma Xi, The Scientific Research Society Since the 1980s, computers have had increasing roles in all aspects of human life—including an involvement in criminal acts. This development has led to the rise of digital forensics, the uncovering and examination of evidence located on all things electronic with digital storage, including computers, cell phones, and networks. Digital forensics researchers and practitione...

  4. Dietary selenium and copper intake by resident undergraduate ...

    African Journals Online (AJOL)

    Dietary selenium and copper intake by resident undergraduate students of the University of Ghana. ... Conclusion: Due to the importance of these micronutrients and in the face of poor nutritional status, as judged by the few that met the required RDAs as well as excess, there is a need to carry out blood analyses to ...

  5. Bioavailability of cobalt, zinc and selenium and anthelmintic effects ...

    African Journals Online (AJOL)

    The present study was carried out to compare the use of liver and plasma analysis as methods of assessing the status of cobalt, zinc and selenium in sheep, and to assess the anthelmintic efficacy of fortified and non-fortified albendazole preparations. Plasma and liver samples were collected in duplicate from fourteen ...

  6. Serum Levels of Selenium, Zinc, Copper and Magnesium in ...

    African Journals Online (AJOL)

    Background: Free radicals have harmful effects on cells and tissues and are thought to be responsible for the pathogenesis of many diseases including bronchial asthma. Selenium (Se), Zinc (Zn), copper (Cu), and magnesium (Mg) are trace elements required for the antioxidant enzymes and hence the optimal functions of ...

  7. Rumen microorganisms decrease bioavailability of inorganic selenium supplements

    Science.gov (United States)

    Despite the availaility of selenium (Se)-enriched trace mineral supplements, we have observed low Se status in cattle and sheep offered traditional inorganic Se supplements. Reasons for this may include inadequate intake or low bioavailability of inorganic Se sources. The objective of this study w...

  8. Effects Of Dietary Supplementation Of Vitamin E And Selenium On ...

    African Journals Online (AJOL)

    This study was carried out to evaluate the combined effects of dietary supplementation of vitamin E (Vit E) and selenium (Se) on total white blood cells, mononucleated cells, polymorphonucleated cells and packed cell volume of Trypanosoma congolense-infected rats (Rattus rattus). Ninety adult R. rattus of pure breed of ...

  9. Selenium dioxide catalysed oxidation of acetic acid hydrazide by ...

    Indian Academy of Sciences (India)

    Abstract. Selenium dioxide catalysed acetic acid hydrazide oxidation by bromate was studied in hydrochloric acid medium. The order in oxidant concentration, substrate and catalyst were found to be unity. Increasing hydrogen ion concentration increases the rate of the reaction due to protonation equilibria of the oxidant.

  10. Addition of Selenium to Carica papaya Linn Pulp Extract Enhances ...

    African Journals Online (AJOL)

    Methods: Phosphate-buffered saline (PBS) and water extracts of unripe Carica papaya. papaya were analyzed for mineral element composition (Ca, calcium; Mg, magnesium; Na, sodium; Fe, iron; Mn, manganese; Zn, zinc; Ag, silver; and Se, selenium) using a microwave-assisted digestion procedure. Atomic absorption ...

  11. Biogeochemistry of selenium isotopes: processes, cycling and paleoenvironmental applications

    NARCIS (Netherlands)

    Mitchell, K.A.

    2012-01-01

    Selenium (Se) is an essential trace element, which, with multiple oxidation states and six stable isotopes, has been suggested as a potentially powerful environmental tracer and paleoenvironmental proxy. Chapter 1 provides a literature review of the Se cycle. While the Se cycle shares some

  12. Concentrations of plasma copper and zinc and blood selenium in ...

    African Journals Online (AJOL)

    Concentrations of plasma copper and zinc as well as blood selenium were determined in single and twin lambs and their dams for a period of 120 days from the birth of the lambs, using Merino, Dohne Merino and SA Mutton Merino sheep. The ewes and their lambs were kept on the same pastures and received the same ...

  13. Zinc and Selenium levels in Motor Mechanics, Paints Sprayers ...

    African Journals Online (AJOL)

    Objectives: This work was designed to determine zinc and Selenium levels in Motor Mechanics, Paints Sprayers, Smokers, Lubricant Workers and BatteryWorkers exposed to lead in Nnewi, South Eastern Nigeria. Subjects and methods: 100 exposed subjects were used for the study. The subjects were aged 25-30 years.

  14. Grain Accumulation of Selenium Species in Rice (Oryza sativa L.)

    Science.gov (United States)

    Selenium (Se) is an essential micronutrient in which up to 1 billion people worldwide are deficient, causing a range of health disorders and potentially an increased risk of certain cancers. Consequently, there is much interest in Se biofortification of rice, the staple food for...

  15. Selenium and mercury interactions wtih emphasis on fish tissue

    Science.gov (United States)

    This review addresses the effects of mercury (Hg) in fish as it relates to the health of the fish themselves as well as potential risks of toxicity in wildlife and humans that consume fish. In particular, it addresses selenium (Se) as a bioindicator of susceptibility to harmful e...

  16. Selenium-containing enzymes in mammals: Chemical perspectives

    Indian Academy of Sciences (India)

    Unknown

    thione peroxidases.5,6,29–32 Many books and reviews available in the literature describe various biological functions of selenium, including nutritional impor- ...... of cancer and represents an attractive target for further pharmacological examination. In recent years, the biological screening has led to the identification of a.

  17. Selenium-containing enzymes in mammals: Chemical perspectives

    Indian Academy of Sciences (India)

    The chemical and biochemical route to the synthesis of the 21st amino acid in living systems, selenocysteine, is described. The incorporation of this rare amino acid residue into proteins is described with emphasis on the role of monoselenophosphate as selenium source. The role of selenocysteine moiety in natural ...

  18. Dyslipidemia, altered erythrocyte fatty acids and selenium are ...

    African Journals Online (AJOL)

    Venous blood sample was drawn from all subjects and erythrocytes separated for the determination of fatty acids. Plasma lipids, selenium and vitamin E levels were also measured. There were no differences in BMI, weight and height among the three groups except for systolic BP that was lower in VD (148.3±41.8mmHg) ...

  19. 2. Serum Selenium levels in Essential hypertension among adults ...

    African Journals Online (AJOL)

    user

    contribute to endothelial dysfunction and cardiovascular remodeling in hypertension and other cardiovascular diseases . Selenium a co-factor of antioxidant enzyme is found incorporated in some antioxidant enzymes such as glutathione peroxidase. (GPx). Antioxidant enzymes are crucial in prevention of oxidative stress ...

  20. Selenium dioxide catalysed oxidation of acetic acid hydrazide by ...

    Indian Academy of Sciences (India)

    Selenium dioxide catalysed acetic acid hydrazide oxidation by bromate was studied in hydrochloric acid medium. The order in oxidant concentration, substrate and catalyst were found to be unity. Increasing hydrogen ion concentration increases the rate of the reaction due to protonation equilibria of the oxidant.

  1. Chemoenzymatic approaches to obtain chiral-centered selenium compounds

    NARCIS (Netherlands)

    Brondani, Patricia B.; Guilmoto, Nathalie M. A. F.; Dudek, Hanna M.; Fraaije, Marco W.; Andrade, Leandro H.

    2012-01-01

    The synthesis of chiral-centered selenium compounds is presented. Enantioselective oxidations of these organoselenium compounds were performed using a wide range of biocatalysts, including Baeyer-Villiger monooxygenases, oxidoreductases-containing Aspergillus terreus and lipase (Cal-B) in the

  2. Selenium affects biosilica formation in the demosponge Suberites domuncula

    NARCIS (Netherlands)

    Mueller, W.E.G.; Borejko, A.; Brandt, D.; Osinga, R.; Ushijima, H.; Hamer, B.; Krasko, A.; Xupeng, C.; Mueller, I.M.; Schroeder, H.C.

    2005-01-01

    Selenium is a trace element found in freshwater and the marine environment. We show that it plays a major role in spicule formation in the demosponge Suberites domuncula. If added to primmorphs, an in vitro sponge cell culture system, it stimulates the formation of siliceous spicules. Using

  3. Ameliorative effects of selenium and vitamin e supplementation on ...

    African Journals Online (AJOL)

    The aim of the present study was to determine the effects of selenium and vitamin E supplementation on some haematological parameters and red blood cell osmotic fragility in Wistar rats subjected to water immersion restraint stress (WRS) (n= 35). Male Wistar rats, weighing 200-220 g were divided in to five groups of ...

  4. Speciation of arsenic and selenium during leaching of fly ash

    NARCIS (Netherlands)

    Hoek, E.E. van der

    1995-01-01

    The leaching (release) of large amounts of oxyanions, such as those of arsenic and selenium, is an major environmental problem when it comes to the disposal or use of coal fly ash. To predict environmentally safe conditions for the disposal or use of fly ash in, for example,

  5. The influence of zinc and selenium on some biochemical responses ...

    African Journals Online (AJOL)

    The influence of zinc and selenium on some biochemical responses (lipid peroxidation, ascorbate, glutathione, growth rate, mineral content, catalase and glutathione peroxidase activities) of cowpea and maize seedlings to water deficit condition and rehydration were investigated. Plants seedlings were exposed to water ...

  6. Selenium and the regulation of cell cycle and apoptosis

    Science.gov (United States)

    Selenium was discovered by Berzelius in 1817, and the essentiality of Se was demonstrated that trace amounts of Se protected against liver necrosis in vitamin E deficient rats in the mid-1950s. The benefits of Se are many including protection against cancer, heart diseases, muscle disorders, immunit...

  7. Synthesis of selenium nanorods with assistance of biomolecule

    Indian Academy of Sciences (India)

    Abstract. Nanorods of one-dimensional (1D) trigonal selenium (t-Se) are synthesized using biomolecule substances for five different aging times (1 h, 2 h, 3 h, 1 day and 4 days) by precipitation method. XRD analysis indicates a shift of the (1 0 1) plane towards higher diffraction angle for 1 day aging time. It is observed that ...

  8. Selenium Characterization In The Global Rice Supply Chain

    Science.gov (United States)

    For up to 1 billion people worldwide, insufficient dietary intake of selenium (Se) is a serious health constraint. Cereals are the dominant Se source for those on low protein diets, as typified by the global malnourished population. With crop Se content constrained largely by u...

  9. Selenium speciation and extractability in Dutch agricultural soils

    NARCIS (Netherlands)

    Supriatin, Supriatin; Weng, Liping; Comans, Rob N.J.

    2015-01-01

    The study aimed to understand selenium (Se) speciation and extractability in Dutch agricultural soils. Top soil samples were taken from 42 grassland fields and 41 arable land fields in the Netherlands. Total Se contents measured in aqua regia were between 0.12 and 1.97mgkg-1(on average

  10. 6. THE ROLE OF SELENIUM IN HUMAN IMMUNITY

    African Journals Online (AJOL)

    Esem

    that selenium has a role in immune function. Immune dysfunction, susceptibility to viral infections and increased mortality are some of the outcomes associated .... In another experimental system, Listeria monocytogenes was administered to mice orally to assess the effect of Se. 17 on innate immunity. Mice were infected ...

  11. Synthesis of selenium nanorods with assistance of biomolecule

    Indian Academy of Sciences (India)

    FTIR analysis confirmed that the presence of stretching and bending vibrations of Se–O in both synthesized and commercial selenium samples at 465, 668 and 1118 cm-1. The FESEM micrographs are evident for the changes of rod size as a function of aging time. It is observed that the optical band gap energy is increased ...

  12. Selenium oxyanion inhibition of hydrogenotrophic and acetoclastic methanogenesis

    NARCIS (Netherlands)

    Lenz, M.; Janzen, N.; Lens, P.N.L.

    2008-01-01

    Inhibitory effects of selenite and selenate towards hydrogenotrophic and acetoclastic methanogenesis were evaluated in anaerobic toxicity assays. The 50% inhibitory concentration (IC50) of both selenium oxyanions was below 6.1 X 10(-5) M in hydrogenotrophic assays, whereas acetoclastic methanogens

  13. JV Task 96 - Phase 2 - Investigating the Importance of the Mercury-Selenium Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Nicholas Ralston; Laura Raymond

    2008-03-01

    In order to improve the understanding of the mercury issue, it is vital to study mercury's effects on selenium physiology. While mercury present in the environment or food sources may pose health risks, the protective effects of selenium have not been adequately considered in establishing regulatory policy. Numerous studies report that vulnerability to mercury toxicity is inversely proportional to selenium status or level. However, selenium status has not been considered in the development of the reference dosage levels for mercury exposure. Experimental animals fed low-selenium diets are far more vulnerable to mercury toxicity than animals fed normal selenium, and animals fed selenium-rich diets are even more resistant. Selenium-dependent enzymes in brain and endocrine tissues can be impaired by excessive mercury exposure, apparently because mercury has an extremely high binding affinity for selenium. When selenium becomes bound to mercury, it is unable to participate in the metabolic cycling of selenoprotein synthesis. Because of mercury-dependent impairments of selenoprotein synthesis, various antioxidant and regulatory functions in brain biochemistry are compromised. This report details a 2-year multiclient-funded research program designed to examine the interactions between mercury and selenium in animal models. The studies explored the effects of dietary intakes of toxic amounts of methylmercury and the protective effects of the normal dietary range of selenium in counteracting mercury toxicity. This study finds that the amounts of selenium present in ocean fish are sufficient to protect against far larger quantities of methylmercury than those present in typical seafoods. Toxic effects of methylmercury exposure were not directly proportional to mercury concentrations in blood, brain, or any other tissues. Instead, mercury toxicity was proportional to molar ratios of mercury relative to selenium. In order to accurately assess risk associated with

  14. Determination of boron in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grazhulene, S.S.; Grossman, O.V.; Kuntscher, K.K.; Malygina, L.I.; Muller, E.N.; Telegin, G.F.

    1985-10-01

    In the determination of boron in amorphous alloys containingFe, Co, B, Si, Ni, and P having unusal magnetic and electrical properties, precise analysis and rapid analysis are necessary. To improve the metrological properties of the existing procedure, to find a rapid determination of boron in amorphous alloys, and to verify the accuracy of the results, in the present work the optimization of the photometric determination after extraction of the BF/sup -//sub 4/ ion pair with methylene blue has been studied, and a boron determination by flame photometry using selective methylation has been developed. The determination of boron by the flame photometric and spectrophotometric methods is shown. When a highly precise determination is needed, the spectrophotometric procedure can be used. This procedure is distinguished by its labor intensity and duration. When the need for reproducibility is less severe, the rapid flame photometric procedure is best.

  15. Wear Resistant Amorphous and Nanocomposite Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Racek, O

    2008-03-26

    Glass forming materials (critical cooling rate <10{sup 4}K.s{sup -1}) are promising for their high corrosion and wear resistance. During rapid cooling, the materials form an amorphous structure that transforms to nanocrystalline during a process of devitrification. High hardness (HV 1690) can be achieved through a controlled crystallization. Thermal spray process has been used to apply coatings, which preserves the amorphous/nanocomposite structure due to a high cooling rate of the feedstock particles during the impact on a substrate. Wear properties have been studied with respect to process conditions and feedstock material properties. Application specific properties such as sliding wear resistance have been correlated with laboratory tests based on instrumented indentation and scratch tests.

  16. Annealing behavior of high permeability amorphous alloys

    International Nuclear Information System (INIS)

    Rabenberg, L.

    1980-06-01

    Effects of low temperature annealing on the magnetic properties of the amorphous alloy Co 71 4 Fe 4 6 Si 9 6 B 14 4 were investigated. Annealing this alloy below 400 0 C results in magnetic hardening; annealing above 400 0 C but below the crystallization temperature results in magnetic softening. Above the crystallization temperature the alloy hardens drastically and irreversibly. Conventional and high resolution transmission electron microscopy were used to show that the magnetic property changes at low temperatures occur while the alloy is truly amorphous. By imaging the magnetic microstructures, Lorentz electron microscopy has been able to detect the presence of microscopic inhomogeneities in this alloy. The low temperature annealing behavior of this alloy has been explained in terms of atomic pair ordering in the presence of the internal molecular field. Lorentz electron microscopy has been used to confirm this explanation

  17. Characterization of diamond amorphized by ion implantation

    International Nuclear Information System (INIS)

    Allen, W.R.; Lee, E.H.

    1992-01-01

    Single crystal diamond has been implanted at 1 MeV with 2 x 10 20 Ar/m 2 . Rutherford backscattering spectrometry in a channeled geometry revealed a broad amorphized region underlying a thin, partially crystalline layer. Raman spectroscopy disclosed modifications in the bonding characteristic of the appearance of non-diamond carbon. The complementary nature of the two analysis techniques is demonstrated. The Knoop hardness of the implanted diamond was reduced by implantation

  18. Metastable states in amorphous chalcogenide semiconductors

    CERN Document Server

    Mikla, Victor I

    2009-01-01

    This book addresses an interesting and technologically important class of materials, the amorphous chalcogenide semiconductors. Experimental results on the structural and electronic metastable states in Se-rich chalcogenides are presented. Special attention is paid to the states in the mobility gap and their sensitivity to various factors such as irradiation, annealing and composition. Photoinduced changes of structure and physical properties are also considered and structural transformation at photocrystallization is studied in detail. Finally, the authors discuss potential applications of th

  19. Influence of tensile stress and frequency on the longitudinal magnetic hysteresis of amorphous wires

    International Nuclear Information System (INIS)

    Torres, Carlos; Maria Munoz, Jose; Hernandez-Gomez, Pablo; Francisco, Carlos de

    2010-01-01

    This work studies the longitudinal magnetic hysteresis of amorphous wires with different Fe or Co compositions through an external magnetic field in the axial direction. Measurements have been carried out with the help of a digitally processed system in the 50 Hz-1 kHz frequency range. In addition, the influence of different tensile stresses has been also analyzed. The results show that both parameters change considerably the magnetic hysteresis of the wires but in a different way depending on their composition. This behaviour has been interpreted in terms of the different domain distribution associated with the opposite sign of the magnetostriction for Fe and Co-based wires, respectively.

  20. Effect of selenium on the lipids of two unicellular marine algae

    Energy Technology Data Exchange (ETDEWEB)

    Gennity, J.M.

    1983-01-01

    The incorporation of selenium into the lipids of two unicellar marine algae has been investigated. Axenic cultures of the green algae Dunaliella primolecta and the red algae Porphyridium cruentum were grown in the presence of sublethal quantities of selenium (10 ppm) as selenite. Both algae were found to contain selenium bound to all purified lipids, except for saturated hydrocarbons. Of the lipids which contain selenium, carotenoid pigments show the greatest selenium concentration (..beta..-carotene: 1.3..mu..gSe/mg lipid; zeaxanthin: 1.1..mu..gSe/mg lipid) in both algae. P. cruentum contains about ten times as much lipid-associated selenium as D. primolecta, even though the lipids of both algae were very similar. This selenium has been shown to be incorporated non-metabolically into the lipid molecule. The lipid-associated selenium is probably non-covalently bound to the lipid molecule and may interact with double bonds. Selenite does not affect the lipid composition of D. primolecta, as compared with algae grown in the absence of added selenium. A selenium-induced 40% decrease in the cell content of eicosapentaenoic acid (20:5omega3) and 20% decrease in arachidonic acid (20:4omega6) in polar lipids (glycolipids plus phospholipids) was observed in P. cruentum. A 25% decrease in the chlorophyll a content of this red algae also occurred. The cell content of other fatty acids, phospholipids and glycolipids was unaltered by selenium. These results are consistent with a selenite-induced oxidation of P. cruentum lipids. Selenium is able to increase the antioxidant potential of algal cells. However, no in vivo selenium-induced protection of algal lipids from oxidation was apparent.

  1. Influence of blood serum selenium on udder health in dairy cows

    Directory of Open Access Journals (Sweden)

    Ivana Davidov

    2014-09-01

    Full Text Available The aim of this study was to determine the effect of selenium concentration in early lactation on mammary gland health and histological characteristics of the udder. The experiment included 30 high-yielding Holstein-Friesian cows. Selenium concentrations in blood and milk serum, and the average somatic cell count in the first and sixth months of lactation were analyzed. After exclusion of the experimental cows from the herd, histological characteristics of the udder were examined (the degree of leukocyte infiltration and the number of granulomas in the parenchyma. The mean selenium concentration in the blood serum was 0.62±0.11 mmol/L and that in the milk serum was 0.12±0.07 mmol/L. Optimal blood levels of selenium were found in 19 cows and suboptimal levels in 11 cows. A significant negative correlation was observed between blood and milk selenium concentrations and somatic cell count in early and mid lactation. There was no relationship between blood selenium concentration, milk selenium concentration and the amount of milk produced. Selenium-deficient cows had a significantly higher milk somatic cell count in early and mid lactation and significantly lower levels of selenium in milk. Upon histological analysis, 120 samples of individual quarters of the udder were grouped according to the degree of leukocyte infiltration and number of granulomas. Results showed that an increase in the degree of leukocyte infiltration and number of granulomas leads to an increase in the proportion of quarters from selenium-deficient cows and a decline in the percentage of quarters from cows exhibiting normal blood selenium concentrations. Selenium has a significant impact on udder health. Changes caused by selenium deficiency occur due to marked inflammation process in the mammary gland.

  2. Binding and Conversion of Selenium in Candida utilis ATCC 9950 Yeasts in Bioreactor Culture

    Directory of Open Access Journals (Sweden)

    Marek Kieliszek

    2017-02-01

    Full Text Available Selenium is considered an essential component of all living organisms. The use of yeasts as a selenium supplement in human nutrition has gained much interest over the last decade. The accumulation and biochemical transformation of selenium in yeast cells is particularly interesting to many researchers. In this article, we present the results of the determination of selenium and selenomethionine content in the biomass of feed yeast Candida utilis ATCC 9950 obtained from the culture grown in a bioreactor. The results indicated that C. utilis cells performed the biotransformation of inorganic selenium(IV to organic derivatives (e.g., selenomethionine. Selenium introduced (20–30 mg Se4+∙L−1 to the experimental media in the form of sodium(IV selenite (Na2SeO3 salt caused a significant increase in selenium content in the biomass of C. utilis,irrespective of the concentration. The highest amount of selenium (1841 μg∙gd.w.−1 was obtained after a 48-h culture in media containing 30 mg Se4+∙L−1. The highest content of selenomethionine (238.8 μg∙gd.w.−1 was found after 48-h culture from the experimental medium that was supplemented with selenium at a concentration of 20 mg Se4+∙L−1. Biomass cell in the cultures supplemented with selenium ranged from 1.5 to 14.1 g∙L−1. The results of this study indicate that yeast cell biomass of C. utilis enriched mainly with the organic forms of selenium can be a valuable source of protein. It creates the possibility of obtaining selenium biocomplexes that can be used in the production of protein-selenium dietary supplements for animals and humans

  3. Features of selenium metabolism in humans living under the conditions of North European Russia.

    Science.gov (United States)

    Parshukova, Olga; Potolitsyna, Natalya; Shadrina, Vera; Chernykh, Aleksei; Bojko, Evgeny

    2014-08-01

    Selenium supplementation and its effects on Northerners have been little studied. The aim of our study was to assess the selenium levels of the inhabitants of North European Russia, the seasonal aspects of selenium supplementation, and the interrelationships between selenium levels and the levels of thyroid gland hormones. To study the particular features of selenium metabolism in Northerners over the course of 1 year, 19 healthy male Caucasian volunteers (18-21 years old) were recruited for the present study. The subjects were military guards in a Northern European region of Russia (Syktyvkar, Russia, 62°N latitude) who spent 6-10-h outdoors daily. The study was conducted over a 12-month period. Selenium levels, glutathione peroxidase (GP) activity, as well as total triiodothyronine (T3), total thyroxin (T4), free thyroxin, free triiodothyronine, and thyrotropin (TSH) levels, were determined in the blood serum. The study subjects showed low levels of plasma selenium throughout the year. We observed a noticeable decrease in plasma selenium levels during the period from May to August, with the lowest levels in July. Selenium levels in the military guards correlated with the levels of selenium-dependent GP enzyme activity throughout the year. Additionally, we demonstrated a significant correlation between selenium and pituitary-thyroid axis hormones (total T3, free T4, and TSH) in periods in which plasma selenium levels were lower than the established normal ranges. Over the course of 1 year, low levels of plasma selenium affect GP activity and thyroid hormone levels in humans living in North European Russia.

  4. Plasma selenium levels and oxidative stress biomarkers: a gene-environment interaction population-based study.

    Science.gov (United States)

    Galan-Chilet, Inmaculada; Tellez-Plaza, Maria; Guallar, Eliseo; De Marco, Griselda; Lopez-Izquierdo, Raul; Gonzalez-Manzano, Isabel; Carmen Tormos, M; Martin-Nuñez, Gracia M; Rojo-Martinez, Gemma; Saez, Guillermo T; Martín-Escudero, Juan C; Redon, Josep; Javier Chaves, F

    2014-09-01

    The role of selenium exposure in preventing chronic disease is controversial, especially in selenium-repleted populations. At high concentrations, selenium exposure may increase oxidative stress. Studies evaluating the interaction of genetic variation in genes involved in oxidative stress pathways and selenium are scarce. We evaluated the cross-sectional association of plasma selenium concentrations with oxidative stress levels, measured as oxidized to reduced glutathione ratio (GSSG/GSH), malondialdehyde (MDA), and 8-oxo-7,8-dihydroguanine (8-oxo-dG) in urine, and the interacting role of genetic variation in oxidative stress candidate genes, in a representative sample of 1445 men and women aged 18-85 years from Spain. The geometric mean of plasma selenium levels in the study sample was 84.76 µg/L. In fully adjusted models the geometric mean ratios for oxidative stress biomarker levels comparing the highest to the lowest quintiles of plasma selenium levels were 0.61 (0.50-0.76) for GSSG/GSH, 0.89 (0.79-1.00) for MDA, and 1.06 (0.96-1.18) for 8-oxo-dG. We observed nonlinear dose-responses of selenium exposure and oxidative stress biomarkers, with plasma selenium concentrations above ~110 μg/L being positively associated with 8-oxo-dG, but inversely associated with GSSG/GSH and MDA. In addition, we identified potential risk genotypes associated with increased levels of oxidative stress markers with high selenium levels. Our findings support that high selenium levels increase oxidative stress in some biological processes. More studies are needed to disentangle the complexity of selenium biology and the relevance of potential gene-selenium interactions in relation to health outcomes in human populations. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Fluctuation microscopy analysis of amorphous silicon models

    International Nuclear Information System (INIS)

    Gibson, J.M.; Treacy, M.M.J.

    2017-01-01

    Highlights: • Studied competing computer models for amorphous silicon and simulated fluctuation microscopy data. • Show that only paracrystalline/random network composite can fit published data. • Specifically show that pure random network or random network with void models do not fit available data. • Identify a new means to measure volume fraction of ordered material. • Identify unreported limitations of the Debye model for simulating fluctuation microscopy data. - Abstract: Using computer-generated models we discuss the use of fluctuation electron microscopy (FEM) to identify the structure of amorphous silicon. We show that a combination of variable resolution FEM to measure the correlation length, with correlograph analysis to obtain the structural motif, can pin down structural correlations. We introduce the method of correlograph variance as a promising means of independently measuring the volume fraction of a paracrystalline composite. From comparisons with published data, we affirm that only a composite material of paracrystalline and continuous random network that is substantially paracrystalline could explain the existing experimental data, and point the way to more precise measurements on amorphous semiconductors. The results are of general interest for other classes of disordered materials.

  6. Intrinsic electron trapping in amorphous oxide

    Science.gov (United States)

    Strand, Jack; Kaviani, Moloud; Afanas’ev, Valeri V.; Lisoni, Judit G.; Shluger, Alexander L.

    2018-03-01

    We demonstrate that electron trapping at intrinsic precursor sites is endemic in non-glass-forming amorphous oxide films. The energy distributions of trapped electron states in ultra-pure prototype amorphous (a)-HfO2 insulator obtained from exhaustive photo-depopulation experiments demonstrate electron states in the energy range of 2–3 eV below the oxide conduction band. These energy distributions are compared to the results of density functional calculations of a-HfO2 models of realistic density. The experimental results can be explained by the presence of intrinsic charge trapping sites formed by under-coordinated Hf cations and elongated Hf–O bonds in a-HfO2. These charge trapping states can capture up to two electrons, forming polarons and bi-polarons. The corresponding trapping sites are different from the dangling-bond type defects responsible for trapping in glass-forming oxides, such as SiO2, in that the traps are formed without bonds being broken. Furthermore, introduction of hydrogen causes formation of somewhat energetically deeper electron traps when a proton is immobilized next to the trapped electron bi-polaron. The proposed novel mechanism of intrinsic charge trapping in a-HfO2 represents a new paradigm for charge trapping in a broad class of non-glass-forming amorphous insulators.

  7. Diagnostic criteria for selenium toxicosis in aquatic birds: histologic lesions

    Science.gov (United States)

    Green, D.E.; Albers, P.H.

    1997-01-01

    Chronic selenium toxicosis was induced in 1-year-old male mallard ducks (Anas platyrhynchos) by feeding selenium, as seleno-DL-methionine, in amounts of 0, 10, 20, 40, and 80 parts per million (ppm) to five groups of 21 ducks each for 16 wk during March to July 1988. All mallards in the 80 ppm group, three in the 40 ppm group, and one in the 20 ppm group died. Histologic lesions in mallards that died of selenosis were hepatocellular vacuolar degeneration progressing to centrolobular and panlobular necrosis, nephrosis, apoptosis of pancreatic exocrine cells, hypermaturity and avascularity of contour feathers of the head with atrophy of feather follicles, lymphocytic necrosis and atrophy of lymphoid organs (spleen, gut-associated lymphoid tissue, and lumbar lymph nodes), and severe atrophy and degeneration of fat. Histologic lesions in surviving mallards in the 40 ppm group, which had tissue residues of selenium comparable to mallards that died, were fewer and much milder than mallards that died; lesions consisted of atrophy of lymphoid tissue, hyalinogranular swelling of hepatocytes, atrophy of seminiferous tubules, and senescence of feathers. No significant histologic lesions were detected in euthanized mallards in the 0, 10 and 20 ppm groups. Based on tissue residues and histologic findings, primarily in the liver, there was a threshold of selenium accumulation above which pathophysiologic changes were rapid and fatal. Pathognomonic histologic lesions of fatal and nonfatal selenosis were not detected. Criteria for diagnosis of fatal selenosis in aquatic birds include consistent histologic lesions in the liver, kidneys, and organs of the immune system. Although histologic changes were present in cases of chronic non-fatal selenosis, these were inconsistent. Consistent features of fatal and non-fatal chronic selenosis were marked weight loss and elevated concentrations of selenium in organs.

  8. Characterization of Amorphous and Co-Amorphous Simvastatin Formulations Prepared by Spray Drying

    Directory of Open Access Journals (Sweden)

    Goedele Craye

    2015-12-01

    Full Text Available In this study, spray drying from aqueous solutions, using the surface-active agent sodium lauryl sulfate (SLS as a solubilizer, was explored as a production method for co-amorphous simvastatin–lysine (SVS-LYS at 1:1 molar mixtures, which previously have been observed to form a co-amorphous mixture upon ball milling. In addition, a spray-dried formulation of SVS without LYS was prepared. Energy-dispersive X-ray spectroscopy (EDS revealed that SLS coated the SVS and SVS-LYS particles upon spray drying. X-ray powder diffraction (XRPD and differential scanning calorimetry (DSC showed that in the spray-dried formulations the remaining crystallinity originated from SLS only. The best dissolution properties and a “spring and parachute” effect were found for SVS spray-dried from a 5% SLS solution without LYS. Despite the presence of at least partially crystalline SLS in the mixtures, all the studied formulations were able to significantly extend the stability of amorphous SVS compared to previous co-amorphous formulations of SVS. The best stability (at least 12 months in dry conditions was observed when SLS was spray-dried with SVS (and LYS. In conclusion, spray drying of SVS and LYS from aqueous surfactant solutions was able to produce formulations with improved physical stability for amorphous SVS.

  9. Selenium speciation in different organs of African catfish (Clarias gariepinus) enriched through a selenium-enriched garlic based diet

    NARCIS (Netherlands)

    Pedrero, Z.; Murillo, S.; Camara, C.; Schram, E.; Luten, J.B.; Feldmann, I.; Jakubowski, N.; Madrid, Y.

    2011-01-01

    Speciation of Se in fish is needed to elucidate the metabolism of this element in living organisms in the marine environment. In this paper, selenium concentration and its species distribution in several organs and tissues (liver, gills, kidney, muscle and gastrointestinal tract) of African catfish

  10. Digital Audiobooks

    DEFF Research Database (Denmark)

    Have, Iben; Pedersen, Birgitte Stougaard

    Audiobooks are rapidly gaining popularity with widely accessible digital downloading and streaming services. The paper is framing how the digital audiobook expands and changes the target groups for book publications and how it as an everyday activity is creating new reading experiences, places...

  11. Digital mammography

    International Nuclear Information System (INIS)

    Cho, Nariya; Cha, Joo Hee; Moon, Woo Kyung

    2005-01-01

    Mammography is the best imaging modality for the detection of early breast cancer in asymptomatic women. However, 10-30% of cases are missed with current film-screen mammography. Digital mammography allows for the separate optimization of image acquisition and display. In addition to the obvious data storage, retrieval, and transmission advantages that digital mammography allows, additional advances such as computer-aided diagnosis, tomosynthesis and dual energy mammography are in development. This review will discuss the technology of digital mammography including detectors and displays, the results of clinical trials comparing film-screen and digital mammography, and the use of computer-aided detection. Digital mammography is a promising new technology for breast cancer detection in the Korean women

  12. Digital Humanities

    DEFF Research Database (Denmark)

    Brügger, Niels

    2016-01-01

    Digital humanities is an umbrella term for theories, methodologies, and practices related to humanities scholarship that use the digital computer as an integrated and essential part of its research and teaching activities. The computer can be used for establishing, finding, collecting, and preser......Digital humanities is an umbrella term for theories, methodologies, and practices related to humanities scholarship that use the digital computer as an integrated and essential part of its research and teaching activities. The computer can be used for establishing, finding, collecting......, and preserving material to study, as an object of study in its own right, as an analytical tool, or for collaborating, and for disseminating results. The term "digital humanities" was coined around 2001, and gained currency within academia in the following years. However, computers had been used within...

  13. Digital displacements

    DEFF Research Database (Denmark)

    Pors, Anja Svejgaard

    2014-01-01

    digital interface. However, the transformation of citizen services from traditional face-to-face interaction to digital self-service gives rise to new practices; some citizens need support to be able to manage self-service through digital tools. A mixture of support and teaching, named co...... digital reforms in Denmark and shows how citizen service is transformed from service to support. The frontline employee’s classical tasks such as casework are being displaced into educational and support-oriented tasks with less professional content. Thus an unintended effect of digitisation is blurred......In recent years digital reforms are being introduced in the municipal landscape of Denmark. The reforms address the interaction between citizen and local authority. The aim is, that by 2015 at least 80 per cent of all correspondence between citizens and public authority will be transmitted through...

  14. Sports Digitalization

    DEFF Research Database (Denmark)

    Xiao, Xiao; Hedman, Jonas; Tan, Felix Ter Chian

    2017-01-01

    evolution, as digital technologies are increasingly entrenched in a wide range of sporting activities and for applications beyond mere performance enhancement. Despite such trends, research on sports digitalization in the IS discipline is surprisingly still nascent. This paper aims at establishing......Ever since its first manifesto in Greece around 3000 years ago, sports as a field has accumulated a long history with strong traditions while at the same time, gone through tremendous changes toward professionalization and commercialization. The current waves of digitalization have intensified its...... a discourse on sports digitalization within the discipline. Toward this, we first provide an understanding of the institutional characteristics of the sports industry, establishing its theoretical importance and relevance in our discipline; second, we reveal the latest trends of digitalization in the sports...

  15. Optimization of wet digestion procedure of blood and tissue for selenium determination by means of 75Se tracer

    International Nuclear Information System (INIS)

    Holynska, B.; Lipinska-Kalita, K.

    1977-01-01

    Selenium-75 tracer has been used for optimization of analytical procedure of selenium determination in blood and tissue. Wet digestion procedure and reduction of selenium to its elemental form with tellurium as coprecipitant have been tested. It is seen that the use of a mixture of perchloric and sulphuric acid with sodium molybdenate for the wet digestion of organic matter followed by the reduction of selenium to its elementary form by a mixture of stannous chloride and hydroxylamine hydrochloride results in very good recovery of selenium. Recovery of selenium obtained with the use of optimized analytical procedure amounts to 95% and precision is equal to 4.2%. (T.I.)

  16. Solvent-mediated amorphous-to-crystalline transformation of nitrendipine in amorphous particle suspensions containing polymers

    DEFF Research Database (Denmark)

    Xia, Dengning; Wu, Jian-Xiong; Cui, Fude

    2012-01-01

    The amorphous-to-crystalline transformation of nitrendipine was investigated using Raman spectroscopy and X-ray powder diffraction (XRPD). The nucleation and growth rate of crystalline nitrendipine in a medium containing poly (vinyl alcohol) (PVA) and polyethylene glycol (PEG 200) were quantitati......The amorphous-to-crystalline transformation of nitrendipine was investigated using Raman spectroscopy and X-ray powder diffraction (XRPD). The nucleation and growth rate of crystalline nitrendipine in a medium containing poly (vinyl alcohol) (PVA) and polyethylene glycol (PEG 200) were...

  17. Selenium status, thyroid volume, and multiple nodule formation in an area with mild iodine deficiency

    DEFF Research Database (Denmark)

    Rasmussen, Lone Banke; Schomburg, Lutz; Kohrle, Josef

    2011-01-01

    ) introduction of iodine fortification. Serum selenium concentration and urinary iodine were measured, and the thyroid gland was examined by ultrasonography in the same subjects. Associations between serum selenium concentration and thyroid parameters were examined in multiple linear regression models...... or logistic regression models.Results: Serum selenium concentration was found to be significantly, negatively associated with thyroid volume (P=0.006), and a low selenium status significantly increased the risk for thyroid enlargement (P=0.007). Furthermore, low serum selenium status had a tendency...... to increase the risk for development of multiple nodules (P=0.087).Conclusions: Low serum selenium concentration was associated with a larger thyroid volume and a higher prevalence of thyroid enlargement....

  18. Nutritional deficiency of selenium secondary to weight loss (bariatric) surgery associated with life-threatening cardiomyopathy.

    Science.gov (United States)

    Boldery, Rachel; Fielding, George; Rafter, Tony; Pascoe, Andrew L; Scalia, Gregory M

    2007-04-01

    Nutritional deficiencies of vitamins and minerals have been associated with reversible and irreversible cardiomyopathic processes. Selenium deficient dilated cardiomyopathy, first described in 1935 in the Keshan Province of China, was sometimes reversed with selenium supplementation. In the past three decades, selenium deficient cardiomyopathy has re-emerged in western medicine secondary to gastrointestinal disorders, long-term total parenteral nutrition (TPN) and gastrointestinal surgery. This report describes a case of selenium deficient cardiomyopathy secondary to the bariatric (weight loss) surgical operation bilio-pancreatic diversion (Scopinaro procedure). This patient presented with life-threatening heart failure nine months after this surgery, having lost 100 kg of body weight. Multiple nutritional deficiencies were detected and corrected including severely depleted selenium levels. Cardiac function and the clinical scenario improved dramatically over three weeks. Screening patients at risk of malnourishment for selenium deficiency as a potential cause of cardiomyopathy is indicated.

  19. Potential reproduction and response of selenium and zinc mineral supplementation on quality of goat samosir semen

    Science.gov (United States)

    Siswoyo, P.; Tafsin, M.; Handarini, R.

    2018-02-01

    The present study was conducted to investigate the effect of suppllementattion of selenium and zinc on semen quality and growth of samosir goat. The experimental design used latin square design (4x4). The treatment supplementation mineral on multi nutrient block (MNB) composed of without sipplementation (p0), +10ppm selenium (p1), +10ppm zinc (p2), +10ppm selenium and +10ppm zinc (p3). The result showed that supplementation mineral selenium and zinc increased significantly (pselenium and zinc influenced motility, viability, volume concentration, and responding hypo osmotic swelling (HOS). Combination supplementation selenium and zinc significanly had higher semen quality than ither treatment. It is concluded that supplementation selenium and zinc improve growth and semen quality of samosir goat.

  20. New scientific challenges - the possibilities of using selenium in poultry nutrition and impact on meat quality

    Science.gov (United States)

    Marković, R.; Glišić, M.; Bošković, M.; Baltić, M. Ž.

    2017-09-01

    Physiological stress is one of many concerns facing modern broiler production. In conditions when birds are exposed to stress, supplementation of selenium, which is a crucial glutathione peroxidase enzymatic cofactor, increases the antioxidant capacity of the animals and decreases the harmful effects of free radicals. Dietary selenium improves production performance and health of animals, and positively affects the immune system, the quality, selenium content and fatty acid composition of meat and eggs. There are several different forms of selenium, the most common dietary supplements being an inorganic form (sodium selenite) and anorganic form (selenomethionine). However, in recent years, new forms of selenium, such as a 2-hydroxy-4-methylselenobutanoic acid (HMSeBA) and nanoselenium, which have more bioavailability, bioefficacy, and low toxicity have been designed. In this short comparative overview discusses the effects of inorganic, organic and nanoforms of selenium on production results, glutathione peroxidase activity, meat quality and level of toxicity in poultry.

  1. Current Knowledge on the Importance of Selenium in Food for Living Organisms: A Review

    Directory of Open Access Journals (Sweden)

    Marek Kieliszek

    2016-05-01

    Full Text Available Selenium is one of the elements classified within the group of micronutrients which are necessary in trace amounts for the proper functioning of organisms. Selenium participates in the protection of cells against excess H2O2, in heavy metal detoxification, and regulation of the immune and reproductive systems as well. It also ensures the proper functioning of the thyroid gland. Selenium induces the occurrence of the selenoprotein synthesis process involved in the antioxidant defense mechanism of the organism. Recent years have brought much success in the studies on selenium. Anticarcinogenic properties of selenium against some cancers have been reported. Supplementation is increasingly becoming a solution to this problem. A large number of different supplementation methods are promoting studies in this area. Slight differences in the selenium content can result in excess or deficiency, therefore supplementation has to be done carefully and cautiously.

  2. Redox-Active Selenium Compounds—From Toxicity and Cell Death to Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Sougat Misra

    2015-05-01

    Full Text Available Selenium is generally known as an antioxidant due to its presence in selenoproteins as selenocysteine, but it is also toxic. The toxic effects of selenium are, however, strictly concentration and chemical species dependent. One class of selenium compounds is a potent inhibitor of cell growth with remarkable tumor specificity. These redox active compounds are pro-oxidative and highly cytotoxic to tumor cells and are promising candidates to be used in chemotherapy against cancer. Herein we elaborate upon the major forms of dietary selenium compounds, their metabolic pathways, and their antioxidant and pro-oxidant potentials with emphasis on cytotoxic mechanisms. Relative cytotoxicity of inorganic selenite and organic selenocystine compounds to different cancer cells are presented as evidence to our perspective. Furthermore, new novel classes of selenium compounds specifically designed to target tumor cells are presented and the potential of selenium in modern oncology is extensively discussed.

  3. Effect of foliar application of selenium on its uptake and speciation in carrot

    DEFF Research Database (Denmark)

    Kápolna, Emese; Hillestrøm, Peter René; Laursen, K.H.

    2009-01-01

    Carrot (Daucus carota) shoots were enriched by selenium using foliar application. Solutions of sodium selenite or sodium selenate at 10 and 100 mu g Se ml(-1), were sprayed on the carrot leaves and the selenium content and uptake rate of selenium were estimated by ICP-MS analysis. Anion and cation......(-1) (dry mass) in the carrot root whereas the selenium concentration in the controls was below the limit of detection at 0.045 mu g Se g(-1) (dry mass). Selenate-enriched carrot leaves accumulated as much as 80 mu g Se g(-1) (dry mass), while the selenite-enriched leaves contained approximately 50 mu...... g Se g(-1) (dry mass). The speciation analyses showed that inorganic selenium was present in both roots and leaves. The predominant metabolised organic forms of selenium in the roots were selenomethionine and gamma-glutamyl-selenomethyl-selenocysteine, regardless of which of the inorganic species...

  4. Evaluation of Selenium Content of Plant Samples Collected from Indigenous Sources for Se-supplementation

    International Nuclear Information System (INIS)

    Mahmud, T.; Sosan, A.; Rehman, R.; Abbas, A.

    2010-01-01

    Selenium contents were evaluated in different plant species such as Canola (Brassica napus), Sunflower (Helianthus annus), Turmeric (Curcuma longa), Soyabean Seeds (Glycine max) and Akk (Calotropis procera) in order to access their possibility for Se-supplementation. The dry ash of bulb of Turmeric and seeds of Canola, Sunflower, and Soyabean were digested in concentrated HNO/sub 3/, HClO/sub 4/ and HCl to obtain selenium (IV). After adding different reagents, stable blue colored complex was formed. From this colored complex, selenium (IV) was determined by UV/visible spectrophotometer. This work was carried out in an attempt to obtain information concerning the amount of selenium present in different plants. It was observed that Akk is a good accumulator of selenium as it contains almost 30 mu g selenium per gram and can be used for different medicinal applications. (author)

  5. Current Knowledge on the Importance of Selenium in Food for Living Organisms: A Review.

    Science.gov (United States)

    Kieliszek, Marek; Błażejak, Stanisław

    2016-05-10

    Selenium is one of the elements classified within the group of micronutrients which are necessary in trace amounts for the proper functioning of organisms. Selenium participates in the protection of cells against excess H₂O₂, in heavy metal detoxification, and regulation of the immune and reproductive systems as well. It also ensures the proper functioning of the thyroid gland. Selenium induces the occurrence of the selenoprotein synthesis process involved in the antioxidant defense mechanism of the organism. Recent years have brought much success in the studies on selenium. Anticarcinogenic properties of selenium against some cancers have been reported. Supplementation is increasingly becoming a solution to this problem. A large number of different supplementation methods are promoting studies in this area. Slight differences in the selenium content can result in excess or deficiency, therefore supplementation has to be done carefully and cautiously.

  6. Comparative effect of organic and inorganic selenium supplementation on selenium status in camel

    Directory of Open Access Journals (Sweden)

    B. Faye

    2014-04-01

    Full Text Available Selenium deficiency is widely described in livestock from the Arabian Peninsula, notably in the camel, and selenium supplementation is based on cattle or horse requirements, usually with sodium selenite product. In order to test the effect of organic Se supplementation vs inorganic Se, 24 pregnant camels were subjected to 3 treatment groups starting one month before delivery (control without Se, non-organic bolus, organic Se. Blood, milk and feces samples were collected from one month before delivery to 3 months of lactation. At delivery, the organic group had a significant higher Se concentration (P < 0.01 in serum (8.21 ± 1.38 μg/100 mL and in colostrum (7.27 ± 2.89 μg/100 mL than in inorganic group (3.90 ± 0.68 and 3.72 ± 0.71, respectively and than in control group (5.45 ± 2.38 and 2.70 ± 0.66, respectively. In calf serum, the Se concentration was significantly higher (P < 0.001 in the two supplemented groups (6.32 ± 2.81 and 5.99 ± 3.31 μg/100 mL in organic and inorganic groups, respectively than in control (3.42 ± 1.41 μg/100 mL. The Se in mother serum decreased after parturition but was highly correlated to Se serum in calf and to Se fecal excretion. Se in milk was lower than in colostrum in all groups (P < 0.01. Treatments had no significant effect on somatic cell count. This study revealed that organic supplementation in camel appeared more efficient.

  7. Active oxygen generation as a possible mechanism of selenium toxicity.

    Science.gov (United States)

    Seko, Y; Imura, N

    1997-09-01

    Selenium plays an important role in scavenging active oxygen (AO) species as an essential constituent of glutathione peroxidase. On the other hand, several reports proposed a possible induction of toxic AO by selenium compounds in vitro. However, some of these experiments including ours, were revealed to conclude on the basis of experimental artifacts, and to have problems in the interpretation of data. Methods or principles so far used for the detection of AO species generated by selenium compound were measurement of chemiluminescence from lucigenin or luminol by AO species, the spectrophotometric analysis of reduction of ferricytochrome c or nitroblue tetrazolium (NBT) by superoxide anion (O2-), electron spin resonance (ESR) spectra using dimethylpyrroline oxide (DMPO) as a spin trapping agent, the deoxyribose decomposition by hydroxyl radical (HO.), the salicylate hydroxylation by HO., and the strand breakage of DNA by AO. Many of these methods together with their principles seem to have some defects which prevent clear conclusion as stated below. (i) Lucigenin was found to mediate the formation of O2- in the presence of selenite and reduced glutathione (GSH). Therefore, lucigenin is not a suitable reagent. (ii) Luminol may also mediate O2- generation in the presence of HO.. (iii) ferricytochrome c can be reduced to ferrocytochrome c in the mixture of selenite and GSH in the absence of oxygen. Moreover, the spectrophotometric method is interfered by turbidity of elemental selenium formed under some conditions in the reaction mixture containing selenite and GSH. (iv) NBT is also reduced by selenium compounds in the absence of O2. (v) ESR signals of AO species were obtained in the reaction mixture containing selenite and GSH, or in the solution of hydrogen selenide in the presence of O2. However, selenide decomposed spin adduct of DMPO with HO. (DMPO-OH). Therefore, the intensity of the signals is not quantitative. (vi) CuZn-SOD is not necessarily a good tool to

  8. Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

    OpenAIRE

    O. Van Overschelde; G. Guisbiers; R. Snyders

    2013-01-01

    Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA) in de-ionized water. Excimer laser (248 nm) operating at low fluence (F ∼ 1 J/cm2) was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the cen...

  9. Selenium contaminated waters: An overview of analytical methods, treatment options and recent advances in sorption methods

    OpenAIRE

    Sílvia C.R. Santos; Gabriela Ungureanu; Rui Boaventura; Cidália Botelho

    2015-01-01

    Selenium is an essential trace element for many organisms, including humans, but it is bioaccumulative and toxic at higher than homeostatic levels. Both selenium deficiency and toxicity are problems around the world. Mines, coal-fired power plants, oil refineries and agriculture are important examples of anthropogenic sources, generating contaminated waters and wastewaters. For reasons of human health and ecotoxicity, selenium concentration has to be controlled in drinking-water and in wastew...

  10. Selenium, selenoproteins and the thyroid gland: interactions in health and disease.

    Science.gov (United States)

    Schomburg, Lutz

    2011-10-18

    The trace element selenium is an essential micronutrient that is required for the biosynthesis of selenocysteine-containing selenoproteins. Most of the known selenoproteins are expressed in the thyroid gland, including some with still unknown functions. Among the well-characterized selenoproteins are the iodothyronine deiodinases, glutathione peroxidases and thioredoxin reductases, enzymes involved in thyroid hormone metabolism, regulation of redox state and protection from oxidative damage. Selenium content in selenium-sensitive tissues such as the liver, kidney or muscle and expression of nonessential selenoproteins, such as the glutathione peroxidases GPx1 and GPx3, is controlled by nutritional supply. The thyroid gland is, however, largely independent from dietary selenium intake and thyroid selenoproteins are preferentially expressed. As a consequence, no explicit effects on thyroid hormone profiles are observed in healthy individuals undergoing selenium supplementation. However, low selenium status correlates with risk of goiter and multiple nodules in European women. Some clinical studies have demonstrated that selenium-deficient patients with autoimmune thyroid disease benefit from selenium supplementation, although the data are conflicting and many parameters must still be defined. The baseline selenium status of an individual could constitute the most important parameter modifying the outcome of selenium supplementation, which might primarily disrupt self-amplifying cycles of the endocrine-immune system interface rectifying the interaction of lymphocytes with thyroid autoantigens. Selenium deficiency is likely to constitute a risk factor for a feedforward derangement of the immune system-thyroid interaction, while selenium supplementation appears to dampen the self-amplifying nature of this derailed interaction.

  11. Effect of dietary selenium and omega-3 fatty acids on muscle composition and quality in broilers

    Directory of Open Access Journals (Sweden)

    Hetland Harald

    2007-10-01

    Full Text Available Abstract Background Human health may be improved if dietary intakes of selenium and omega-3 fatty acids are increased. Consumption of broiler meat is increasing, and the meat content of selenium and omega-3 fatty acids are affected by the composition of broiler feed. A two-way analyses of variance was used to study the effect of feed containing omega-3 rich plant oils and selenium enriched yeast on broiler meat composition, antioxidation- and sensory parameters. Four different wheat-based dietary treatments supplemented with 5% rapeseed oil or 4% rapeseed oil plus 1% linseed oil, and either 0.50 mg selenium or 0.84 mg selenium (organic form per kg diet was fed to newly hatched broilers for 22 days. Results The different dietary treatments gave distinct different concentrations of selenium and fatty acids in thigh muscle; one percent linseed oil in the diet increased the concentration of the omega-3 fatty acids 18:3, 20:5 and 22:5, and 0.84 mg selenium per kg diet gave muscle selenium concentration at the same level as is in fish muscle (0.39 mg/kg muscle. The high selenium intake also resulted in increased concentration of the long-chain omega-3 fatty acids EPA (20:5, DPA (22:5 and DHA (22:6, thus it may be speculated if high dietary selenium might have a role in increasing the concentration of EPA, DPA and DHA in tissues after intake of plant oils contning omega-3 fatty acids. Conclusion Moderate modifications of broiler feed may give a healthier broiler meat, having increased content of selenium and omega-3 fatty acids. High intakes of selenium (organic form may increase the concentration of very long-chain omega-3 fatty acids in muscle.

  12. Topographical Distribution of Arsenic, Manganese, and Selenium in the Normal Human Brain

    DEFF Research Database (Denmark)

    Larsen, Niels Agersnap; Pakkenberg, H.; Damsgaard, Else

    1979-01-01

    The concentrations of arsenic, manganese and selenium per gram wet tissue weight were determined in samples from 24 areas of normal human brains from 5 persons with ages ranging from 15 to 81 years of age. The concentrations of the 3 elements were determined for each sample by means of neutron......% for selenium. The results seem to indicate that arsenic is associated with the lipid phase, manganese with the dry matter and selenium with the aqueous phase of brain tissue....

  13. Atomistic modeling of ion beam induced amorphization in silicon

    International Nuclear Information System (INIS)

    Pelaz, Lourdes; Marques, Luis A.; Lopez, Pedro; Santos, Ivan; Aboy, Maria; Barbolla, Juan

    2005-01-01

    Ion beam induced amorphization in Si has attracted significant interest since the beginning of the use of ion implantation for the fabrication of Si devices. Nowadays, a renewed interest in the modeling of amorphization mechanisms at atomic level has arisen due to the use of preamorphizing implants and high dopant implantation doses for the fabrication of nanometric-scale Si devices. In this work, we briefly describe the existing phenomenological and defect-based amorphization models. We focus on the atomistic model we have developed to describe ion beam induced amorphization in Si. In our model, the building block for the amorphous phase is the bond defect or IV pair, whose stability increases with the number of surrounding IV pairs. This feature explains the regrowth behavior of different damage topologies and the kinetics of the crystalline to amorphous transition. The model provides excellent quantitative agreement with experimental results

  14. Digital radiography

    International Nuclear Information System (INIS)

    Coulomb, M.; Dal Soglio, S.; Pittet-Barbier, L.; Ranchoup, Y.; Thony, F.; Ferretti, G.; Robert, F.

    1992-01-01

    Digital projection radiography may replace conventional radiography some day, provided it can meet several requirements: equal or better diagnostic effectiveness of the screen-film systems; reasonable image cost; real improvement in the productivity of the Departments of Imaging. All digital radiographic systems include an X-ray source, an image acquisition and formatting sub-system, a display and manipulation sub-system, and archiving subsystem and a laser editing system, preferably shared by other sources of digital images. Three digitization processes are available: digitization of the radiographic film, digital fluorography and phospholuminescent detectors with memory. The advantages of digital fluoroscopy are appealing: real-time image acquisition, suppression of cassettes; but its disadvantages are far from negligible: it cannot be applied to bedside radiography, the field of examination is limited, and the wide-field spatial resolution is poor. Phospholuminescent detectors with memory have great advantages: they can be used for bedside radiographs and on all the common radiographic systems; spatial resolution is satisfactory; its current disadvantages are considerable. These two systems, have common properties making up the entire philosophy of digital radiology and specific features that must guide our choice according to the application. Digital fluorography is best applied in pediatric radiology. However, evaluation works have showed that it was applicable with sufficient quality to many indications of general radiology in which a fluoroscopic control and fast acquisition of the images are essential; the time gained on the examination may be considerable, as well as the savings on film. Detectors with memory are required for bedside radiographs, in osteoarticular and thoracic radiology, in all cases of traumatic emergency and in the resuscitation and intensive care departments

  15. Digital radiography

    International Nuclear Information System (INIS)

    Zani, M.L.

    2002-01-01

    X-ray radiography is a very common technique used to check the homogeneity of a material or the inside of a mechanical part. Generally the radiation that goes through the material to check, produced an image on a sensitized film. This method requires time because the film needs to be developed, digital radiography has no longer this inconvenient. In digital radiography the film is replaced by digital data and can be processed as any computer file. This new technique is promising but its main inconvenient is that today its resolution is not so good as that of film radiography. (A.C.)

  16. Digital electronics

    CERN Document Server

    Morris, John

    2013-01-01

    An essential companion to John C Morris's 'Analogue Electronics', this clear and accessible text is designed for electronics students, teachers and enthusiasts who already have a basic understanding of electronics, and who wish to develop their knowledge of digital techniques and applications. Employing a discovery-based approach, the author covers fundamental theory before going on to develop an appreciation of logic networks, integrated circuit applications and analogue-digital conversion. A section on digital fault finding and useful ic data sheets completes th

  17. Digital Leadership

    DEFF Research Database (Denmark)

    Zupancic, Tadeja; Verbeke, Johan; Achten, Henri

    2016-01-01

    Leadership is an important quality in organisations. Leadership is needed to introduce change and innovation. In our opinion, in architectural and design practices, the role of leadership has not yet been sufficiently studied, especially when it comes to the role of digital tools and media....... With this paper we intend to initiate a discussion in the eCAADe community to reflect and develop ideas in order to develop digital leadership skills amongst the membership. This paper introduces some important aspects, which may be valuable to look into when developing digital leadership skills....

  18. Digital radiography

    International Nuclear Information System (INIS)

    Kusano, Shoichi

    1993-01-01

    Firstly, from an historic point of view, fundamental concepts on digital imaging were reviewed to provide a foundation for discussion of digital radiography. Secondly, this review summarized the results of ongoing research in computed radiography that replaces the conventional film-screen system with a photo-stimulable phosphor plate; and thirdly, image quality, radiation protection, and image processing techniques were discussed with emphasis on picture archiving and communication system environment as our final goal. Finally, future expansion of digital radiography was described based on the present utilization of computed tomography at the National Defense Medical College Hospital. (author) 60 refs

  19. Relationship of dietary intake of fish and non-fish selenium to serum lipids in Japanese rural coastal community.

    Science.gov (United States)

    Miyazaki, Yukiko; Koyama, Hiroshi; Nojiri, Masami; Suzuki, Shosuke

    2002-01-01

    Several studies have suggested that dietary selenium deficiency may be associated with an increased risk of coronary heart disease (CHD). In the present study, 55 men and 71 women were selected from participants in a health examination in a rural coastal community in Japan. The mean dietary selenium intake calculated from the simple food frequency questionnaire (SFFQ) was 127.5 micrograms/day. Fish was the major source of dietary selenium and it contributed to 68.7% of the daily total. HDL cholesterol was higher in the middle selenium intake group and in the high selenium intake group than in the low selenium intake group in all subjects and for males, and a significant difference was found between the middle selenium intake group and the low selenium intake group. The atherogenic index was significantly higher in the low selenium intake group than in the middle selenium intake group and in the high selenium intake group in males. GPx activity, total cholesterol and triacylglycerols did not show any significant differences among the three different selenium intake groups. Dietary intake of non-fish Se had a positive correlation with HDL cholesterol, and an inverse correlation with the atherogenic index in all subjects and for females. On the other hand, dietary intake of fish-Se had no relationship with any serum lipids. Non-fish Se is an important factor in selenium status for the prevention of CHD.

  20. EFFECT OF SELENIUM SUPPLEMENTATION ON PIG PRODUCTION PROPERTIES, ANTIOXIDANT STATUS AND MEAT QUALITY

    Directory of Open Access Journals (Sweden)

    Tomislav Šperanda

    2013-12-01

    Full Text Available Food containing functional ingredients to achieve a positive effect on health and reducing the risk of infection is increasing production. It is also very important to improve the quality of pork with respect to change the genetic makeup of pigs that raised leanness, being inversely correlated with the quality of meat. This study monitored the effectiveness of addition of higher doses of organic selenium in the diet of fattening pigs in relation to their growth, immunity, antioxidant power, the quality of meat and possibility of meat enriching with selenium. The experiment was carried out on 100 pigs (crossbred WJxSLxP of both sexes, from 28 kg to 98 kg body weight during a period of 98 days. Piglets fed the finished feed mixture for fattening up to 60 kg (ST-1 and a mixture for fattening up to 100 kg (DM-2 in addition, by the groups as follows: K-0. 3 mg/kg organic selenium, P1-0.5 mg/kg inorganic selenium, P2-0.5 mg/kg organic selenium, P3-0.5 mg/ kg organic selenium +0.2% zeolite clinoptilolite treated vibrotehnology and P4-gradual increase in selenium so that the concentration of the last month was 0.7 mg/ kg diet of organic selenium. All groups of pigs fed high concentration of organic selenium had a higher proportion of lymphocytes, especially CD4 T lymphocytes. Glutathione peroxidase activity was higher in all groups fed elevated selenium levels and significantly higher in the P3 and P4 groups 71st and 98th days of the trials. Glutathione reductase was significantly higher in the P3 and P4 group 98th days compared to the control. Antioxidant indicators suggested increased antioxidant protection in groups supplemented with 0.5 ppm organic selenium and selenium formulations of the same with the addition of zeolite under stress intensive pig production. No differences were found in the products of lipid peroxidation (TBARS in raw meat or in meat after a week in refrigerator storage. By histological examination statistically higher level of

  1. Examination of the selenium content of wheat grasses produced in different soil types in Csik Basin

    Directory of Open Access Journals (Sweden)

    Tamás M.

    2015-01-01

    Full Text Available In the course of the research, we determined selenium and dry matter content of 35 wheat grass and 35 wheat seed samples. The selenium content of the preparation plant probes was measured by spectrofluorimetric determination (λexcitation = 380 nm, λemission = 519 nm of the resulted piazselenol complex. It was established that between the selenium content of the wheat grass and wheat seed the correlation coefficient was 0.36 at p = 0.05 level, which indicates a medium-close correlation. Similarly, there was a medium-close correlation between the selenium content of the wheat grass calculated on dry-matter basis and total selenium content of the wheat, with a correlation coefficient of 0.40 at p = 0.02 level. Afterwards, beside the selenium content, we measured the selenomethionine content by ion-exchange chromatography and highperformance liquid chromatography, and the organic selenium content was calculated. A very close correlation was established between the total selenium, selenomethionine and calculated organic selenium content of wheat (the correlation coefficients were between 0.92 and 0.99 at p = 0.01 level. The correlation between the selenomethionine content of wheat grass and wheat seed was very weak (r = 0.23.

  2. Selenium homeostasis and induction of thioredoxin reductase during long term selenite supplementation in the rat

    DEFF Research Database (Denmark)

    Erkhembayar, Suvd; Mollbrink, Annelie; Eriksson, Malin

    2011-01-01

    selenium levels was also seen, and the induction of TrxR1 mRNA was seen only during the first three days of treatment, when the levels of selenium in the liver were increasing. Sodium selenite at 1 and 5μg/mL did not affect body weight or relative liver mass. We concluded that long-term treatment...... with selenite did not cause accumulation of selenium and that the activity of TrxR1 in the liver rose with the selenium levels. We therefore suggest that sodium selenite at doses up to 5μg/mL could be used for long-term tumour prevention....

  3. A STUDY OF THE ASSOCIATION BETWEEN SELENIUM AND CARDIOVASCULAR DISEASE IN LAMPUNG, INDONESIA.

    Science.gov (United States)

    Mutakin; Rivai, Ida F; Setiawan, Andi; Abdulah, Rizky; Kobayashi, Kenji; Yamazaki, Chiho; Kameo, Satomi; Nakazawa, Minato; Koyama, Hiroshi

    2016-03-01

    Selenium deficient areas have been associated with a higher prevalence of cardiovascular disease in some countries. In this study, we investigated the correlation between cardiovascular disease prevalence and selenium concentration in paddy soil and rice grains, the main staple food in Lampung, Indonesia. Paddy soil and rice samples (n(s) = 35) from eight regencies (n(d) = 8) in Lampung were analyzed for selenium content. The prevalences of heart disease, stroke, and hypertension in those regencies were obtained from the Ministry of Health of Indonesia. The Shapiro-Wilk's test was used to examine the data distribution. The Pearson's correlation was used to examine the correlation between cardiovascular disease prevalence and selenium concentration in the paddy soil and rice grains. Heart disease prevalence was negatively correlated with the selenium concentration in the paddy soil (r = -0.77, p = 0.02) and rice grain (r = -0.71, p = 0.05). A negative correlation was seen for stroke prevalence and selenium concentration in paddy soil (r = -0.76, p = 0.02). Hypertension prevalence was negatively correlated with the selenium concentration in the rice grains (r = -0.83, p = 0.01). These findings suggest that the selenium concentration in paddy soil and rice grains in the Lampung area may play a role in the fact the area has the lowest cardiovascular disease prevalence in Indonesia. Keywords: selenium, cardiovascular diseases, paddy soil, rice grain, Indonesia

  4. Direct solution-phase synthesis of Se submicrotubes using Se powder as selenium source

    International Nuclear Information System (INIS)

    Yan Shancheng; Wang Haitao; Zhang Yuping; Li Shuchun; Xiao Zhongdang

    2009-01-01

    The selenium submicrotubes were directly prepared using Se powder as selenium source by microwave-assisted method. Field-emission scan electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were adopted to characterize the as-prepared products. The results of high-resolution transmission electron microscopy (HRTEM) and XRD pattern proved that the selenium submicrotubes were single crystalline in nature and [0 0 1] oriented. A possible growth mechanism of the selenium submicrotubes was proposed. The effects of the experimental conditions, such as alkaline concentration and solvent properties, on the morphology and dimension of the products have also been discussed

  5. Selenium in the central nervous system of the rat after exposure to L-selenomethionine

    DEFF Research Database (Denmark)

    Grønbæk, Henning; Thorlacius-Ussing, O.

    1990-01-01

    ~ek and Thorlacius-Ussing 1988). Earlier studies have correlated this selenium accumulation in the anterior pituitary to endocrine dysfunction in selenium-intoxicated animals (Jensen 1975; Glover et al. 1979). Recent results from our laboratory have demonstrated a substantial decrease in growth hormone secretion...... in the anterior pituitary of rats exposed to sodium selenite (Thorlacius-Ussing and Danscher 1985). This histochemical method demonstrates complexes of exogenous selenium and endogenous metal. In the central nervous system and the anterior pituitary, selenium is suggested to form bonds with zinc (Danscher 1984...

  6. Loss of selenium in drying and storage of agronomic plant species

    DEFF Research Database (Denmark)

    Nielsen, Gunnar Gissel

    1970-01-01

    In two experiments with Se75, loss of selenium from agricultural species was noted during both drying and storage. The loss of selenium during drying was to some extent overshadowed by the influence of self-absorption caused by the water in the fresh material. The results showed that even plant m...... material of non-indicator plantslose volatile selenium at drying temperatures of 60°C or higher, and in some cases even at temperatures below 60°C. The results also showed that storage as briquettes gives the lowest storage loss of selenium....

  7. The effect of different selenium levels on production performance and biochemical parameters of broilers

    Directory of Open Access Journals (Sweden)

    Guoshun Chen

    2013-10-01

    Full Text Available Selenium (Se is an essential trace element for animal and human. Supplementation of Se usually in livestock diet has been proved as effective element. This study was conducted to investigate the effect of adding different levels of selenium yeast on growth performance, slaughter performance, immune trait, oxidation resistance, meat quality and selenium content in tissue of broilers to comprehensively evaluate the effect of selenium. A total of 540 day-old Arbor Acres (AA broilers were selected and feeded with the diets of treatments supplemented with 0.0, 0.3, 0.5, l.0 and 2.0 mg/kg organic selenium respectively. The trial period was 42 days and divided into two periods. Our results showed that effect of different levels of selenium on growth performance, slaughter performance, the immune status, drip loss and flesh had not significant difference (P>0.05. The activities of serum glutathione peroxidase (GSH-Px, total superoxide dismutase (TSOD, the abilities to inhibit hydroxyl radical (OH•, total antioxidant capacity (T-AOC and the content of GSH were significantly increased along with selenium level (P<0.05, whereas the content of malondialdehyde (MDA was significantly decreased with organic selenium level (P<0.05. Our results demonstrated that organic selenium had no obvious effect on production performance of broilers, but significantly influenced the broiler oxidation resistance.

  8. Selenium dynamics in boreal streams: the role of wetlands and changing groundwater tables.

    Science.gov (United States)

    Lidman, Fredrik; Mörth, Carl-Magnus; Björkvald, Louise; Laudon, Hjalmar

    2011-04-01

    The concentrations of selenium in 10 catchments of a stream network in northern Sweden were monitored over two years, yielding almost 350 observations of selenium concentrations in streamwater. The export of selenium was found to be systematically greater from forests than from mires. Accounting for atmospheric deposition, which was monitored over four years, there was a net accumulation of selenium in mires, while the export from forest soils was approximately equal to the atmospheric deposition. In forest dominated catchments the concentrations of selenium oscillated rapidly back and forth from high to low levels during spring floods. High selenium concentrations coincided with rising groundwater tables in the riparian forest soils, while low selenium concentrations were associated with receding groundwater. Thermodynamic modeling indicated that precipitation of elemental selenium would occur under reducing conditions in the riparian soils. Since changes in the redox conditions are likely to occur near the transition from the unsaturated to the saturated zone, it is hypothesized that the transport of selenium from forest soils to streams is controlled by redox reactions in riparian soils.

  9. Serum selenium concentration is associated with metabolic factors in the elderly: a cross-sectional study

    Directory of Open Access Journals (Sweden)

    Huang Hui-Ying

    2010-05-01

    Full Text Available Abstract Background Selenium is an essential micronutrient known for its antioxidant function. However, the association of serum selenium with lipid profiles and fasting glucose are inconsistent in populations with average intake of selenium. Furthermore, there were few studies conducted specifically for the elderly. This study examined the relationship of serum selenium concentration with serum lipids and fasting glucose in the Taiwanese elderly population. Methods This was a cross-sectional study of 200 males and females aged 65-85 years (mean 71.5 ± 4.6 years from Taipei, Taiwan. Serum selenium was measured by inductively coupled plasma-mass spectrometer. The association between serum selenium and metabolic factors was examined using a multivariate linear regression analysis after controlling several confounders. Results The mean serum selenium concentration was 1.14 μmol/L, without significant difference between sexes. Total cholesterol, triglycerides, and LDL cholesterol increased significantly with serum selenium concentration (P P P P Conclusions Total cholesterol, triglycerides, and LDL cholesterol, and fasting serum glucose concentrations increased significantly with serum selenium concentration in the Taiwanese elderly. The underlying mechanism warrants further research.

  10. Amorphization of equimolar alloys with HCP elements during mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Liang [Materials and Electro-Optics Research Division, Chung-Shan Institute of Science and Technology, Armaments Bureau, MND, P.O. Box 90008-8-5, Lung-Tan, Tao-Yuan 32599, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Tsai, Che-Wei; Juan, Chien-Chang; Chuang, Ming-Hao [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Yeh, Jien-Wei, E-mail: jwyeh@mx.nthu.edu.t [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Chin, Tsung-Shune [Department of Materials Science and Engineering, Feng Chia University, 100, Wenhwa Rd., Seatwen District, Taichung 40724, Taiwan (China); Chen, Swe-Kai [Center for Nanotechnology, Materials Science and Microsystems, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China)

    2010-09-10

    This study prepares two equimolar alloys, entirely composed of HCP elements, BeCoMgTi and BeCoMgTiZn, from elemental powders by mechanical alloying. No crystalline solid solutions and compounds formed during milling except an amorphous phase formed gradually until full amorphization was attained. The amorphization processes of these two alloys conform to type II according to the Weeber and Bakker classification based on binary alloys. The inhibition of crystalline solid solutions and compounds before amorphization relates to chemical compatibility, high entropy effect and large atomic size difference effect.

  11. Excessively High Vapor Pressure of Al-based Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Jae Im Jeong

    2015-10-01

    Full Text Available Aluminum-based amorphous alloys exhibited an abnormally high vapor pressure at their approximate glass transition temperatures. The vapor pressure was confirmed by the formation of Al nanocrystallites from condensation, which was attributed to weight loss of the amorphous alloys. The amount of weight loss varied with the amorphous alloy compositions and was inversely proportional to their glass-forming ability. The vapor pressure of the amorphous alloys around 573 K was close to the vapor pressure of crystalline Al near its melting temperature, 873 K. Our results strongly suggest the possibility of fabricating nanocrystallites or thin films by evaporation at low temperatures.

  12. Fast surface crystallization of amorphous griseofulvin below T g.

    Science.gov (United States)

    Zhu, Lei; Jona, Janan; Nagapudi, Karthik; Wu, Tian

    2010-08-01

    To study crystal growth rates of amorphous griseofulvin (GSF) below its glass transition temperature (T (g)) and the effect of surface crystallization on the overall crystallization kinetics of amorphous GSF. Amorphous GSF was generated by melt quenching. Surface and bulk crystal growth rates were determined using polarized light microscope. X-ray powder diffraction (XRPD) and Raman microscopy were used to identify the polymorph of the crystals. Crystallization kinetics of amorphous GSF powder stored at 40 degrees C (T (g)-48 degrees C) and room temperature (T (g)-66 degrees C) was monitored using XRPD. Crystal growth at the surface of amorphous GSF is 10- to 100-fold faster than that in the bulk. The surface crystal growth can be suppressed by an ultrathin gold coating. Below T (g), the crystallization of amorphous GSF powder was biphasic with a rapid initial crystallization stage dominated by the surface crystallization and a slow or suspended late stage controlled by the bulk crystallization. GSF exhibits the fastest surface crystallization kinetics among the known amorphous pharmaceutical solids. Well below T (g), surface crystallization dominated the overall crystallization kinetics of amorphous GSF powder. Thus, surface crystallization should be distinguished from bulk crystallization in studying, modeling and controlling the crystallization of amorphous solids.

  13. Amorphization kinetics of Zr3Fe under electron irradiation

    International Nuclear Information System (INIS)

    Motta, A.T.; Howe, L.M.; Okamoto, P.R.

    1994-11-01

    Previous investigations using 40 Ar ion bombardments have revealed that Zr 3 Fe, which has an orthorhombic crystal structure, undergoes an irradiation-induced transformation from the crystalline to the amorphous state. In the present investigation, 0.9 MeV electron irradiations were performed at 28 - 220 K in a high-voltage electron microscope (HVEM). By measuring the onset, spread and final size of the amorphous region, factoring in the Gaussian distribution of the beam, a kinetic description of the amorphization in terms of dose, dose rate and temperature was obtained. The critical temperature for amorphization by electron irradiation was found to be ∼ 220 K, compared with 570 - 625 K for 40 Ar ion irradiation. Also, the dose-to-amorphization increased exponentially with temperature. Results indicated that the rate of growth of the amorphous region under the electron beam decreased with increasing temperature and the dose-to-amorphization decreased with increasing dose rate. The size of the amorphous region saturated after a given dose, the final size decreasing with increasing temperature, and it is argued that this is related to the existence of a critical dose rate, which increases with temperature, and below which no amorphization occurs. (author). 26 refs., 6 figs

  14. Amorphization of silicon by femtosecond laser pulses

    International Nuclear Information System (INIS)

    Jia, Jimmy; Li Ming; Thompson, Carl V.

    2004-01-01

    We have used femtosecond laser pulses to drill submicron holes in single crystal silicon films in silicon-on-insulator structures. Cross-sectional transmission electron microscopy and energy dispersive x-ray analysis of material adjacent to the ablated holes indicates the formation of a layer of amorphous Si. This demonstrates that even when material is ablated using femtosecond pulses near the single pulse ablation threshold, sufficient heating of the surrounding material occurs to create a molten zone which solidifies so rapidly that crystallization is bypassed

  15. Atomic Distribution in Catalytic Amorphous Metals

    Directory of Open Access Journals (Sweden)

    Sanghita Mridha

    2015-01-01

    Full Text Available The atomic distribution in catalytically active metallic glass alloys, Pd43Cu27Ni10P20 and Pt57.5Cu14.7Ni5.3P22.5, was investigated using three-dimensional atom probe microscopy. Atom probe analysis showed uniform distribution of constituent elements for both the starting amorphous alloys, with no phase separation. Both the crystallized alloys showed eutectic microstructure with a very sharp interface (~0.5 nm as determined from atom probe. The atomic distribution in the devitrified state is explained based on the “fragile liquid” behavior for these noble-metal glassy alloys.

  16. Protective amorphous carbon coatings on glass substrates

    Science.gov (United States)

    Silins, Kaspars; Baránková, Hana; Bardos, Ladislav

    2017-11-01

    Thick amorphous carbon films were deposited by the Magnets-in-Motion (M-M) rf linear hollow cathode at varying acetylene contents in Ar in a hybrid PVD/PE-CVD process directly on glass substrates. The hollow cathode plates manufactured from graphite were used as the PVD target. The measurements show that the films can reach thickness of up to 50 μm at deposition rates of up to 2.5 μm/min. Scratch test measurements confirm that well adhering films several μm thick can be achieved at C2H2 contents of up to 0.5%.

  17. Medical imaging applications of amorphous silicon

    International Nuclear Information System (INIS)

    Mireshghi, A.; Drewery, J.S.; Hong, W.S.; Jing, T.; Kaplan, S.N.; Lee, H.K.; Perez-Mendez, V.

    1994-07-01

    Two dimensional hydrogenated amorphous silicon (a-Si:H) pixel arrays are good candidates as flat-panel imagers for applications in medical imaging. Various performance characteristics of these imagers are reviewed and compared with currently used equipments. An important component in the a-Si:H imager is the scintillator screen. A new approach for fabrication of high resolution CsI(Tl) scintillator layers, appropriate for coupling to a-Si:H arrays, are presented. For nuclear medicine applications, a new a-Si:H based gamma camera is introduced and Monte Carlo simulation is used to evaluate its performance

  18. Benefits of raising crops and animals naturally enriched with selenium in areas with selenium deficiency

    International Nuclear Information System (INIS)

    Dzhudich, I.S.

    2008-01-01

    Selenium (Se) is implicated in the protection of body tissues against oxidative stress, maintenance of defences against infection, and modulation of growth and development. The natural environment has a profound influence on its contents in the food chain and the development and distribution of Se responsive diseases. To overcome the Se deficiency problem and assure safe and adequate Se intakes, different methods were developed. Its efficiency depends on Se compounds absorption, its nutritional availability, long-term retention, convertibility of tissue Se stores into biologically active forms and the history of Se nutrition, influencing the proportion of absorbed retained, or excreted Se from diet. Since the dominant metabolically active Se forms are found in proteins as seleno analogues of sulphur amino acids, rather than selenotrisulphides and other acid labile Se compounds, we developed our own procedure for foliar enrichment of crops with Se, enabling the production of crops and animals with adequate Se content in low Se areas. By foliar application of Se salts, we optimize Se contents of many parameters important for plants quality, thus contributing to the better status of many essential, in diet often deficient nutrients. The utilization of these crops in animal nutrition, contributes to the nutritive value of animal products not only due to adequate Se content, but also higher values of other quality parameters. Consumption of such produced crops and animal products by humans in areas with low dietary Se intake has shown to have significant overall health benefits

  19. Characterization of Amorphous and Co-Amorphous Simvastatin Formulations Prepared by Spray Drying

    DEFF Research Database (Denmark)

    Craye, Goedele; Löbmann, Korbinian; Grohganz, Holger

    2015-01-01

    In this study, spray drying from aqueous solutions, using the surface-active agent sodium lauryl sulfate (SLS) as a solubilizer, was explored as a production method for co-amorphous simvastatin-lysine (SVS-LYS) at 1:1 molar mixtures, which previously have been observed to form a co...

  20. Digital Snaps

    DEFF Research Database (Denmark)

    Sandbye, Mette; Larsen, Jonas

    Purikura Photography / Mette Sandbye -- ch. 7. 'Buying an Instrument Does Not Necessarily Make You a Musician': Studio Photography and the Digital Revolution / Sigrid Lien -- pt. III. NEW PUBLIC FORMS -- ch. 8 Paparazzi Photography, Seriality and the Digital Photo Archive / Anne Jerslev and Mette Mortensen......The New Face of Snapshot Photography / Jonas Larsen and Mette Sandbye -- pt. I. IMAGES ON WEB 2.0 AND THE CAMERA PHONE -- ch. 1. Overlooking, Rarely Looking and Not Looking / Martin Lister -- ch. 2. The (Im)mobile Life of Digital Photographs: The Case of Tourist Photography / Jonas Larsen -- ch. 3....... Distance as the New Punctum / Mikko Villi -- pt. II. FAMILY ALBUMS IN TRANSITION -- ch. 4. How Digital Technologies Do Family Snaps, Only Better / Gillian Rose -- ch. 5. Friendship Photography: Memory, Mobility and Social Networking / Joanne Garde-Hansen -- ch. 6. Play, Process and Materiality in Japanese...

  1. Digital Discretion

    DEFF Research Database (Denmark)

    Busch, Peter Andre; Zinner Henriksen, Helle

    2018-01-01

    discretion is suggested to reduce this footprint by influencing or replacing their discretionary practices using ICT. What is less researched is whether digital discretion can cause changes in public policy outcomes, and under what conditions such changes can occur. Using the concept of public service values......This study reviews 44 peer-reviewed articles on digital discretion published in the period from 1998 to January 2017. Street-level bureaucrats have traditionally had a wide ability to exercise discretion stirring debate since they can add their personal footprint on public policies. Digital......, we suggest that digital discretion can strengthen ethical and democratic values but weaken professional and relational values. Furthermore, we conclude that contextual factors such as considerations made by policy makers on the macro-level and the degree of professionalization of street...

  2. Digital fabrication

    CERN Document Server

    2012-01-01

    The Winter 2012 (vol. 14 no. 3) issue of the Nexus Network Journal features seven original papers dedicated to the theme “Digital Fabrication”. Digital fabrication is changing architecture in fundamental ways in every phase, from concept to artifact. Projects growing out of research in digital fabrication are dependent on software that is entirely surface-oriented in its underlying mathematics. Decisions made during design, prototyping, fabrication and assembly rely on codes, scripts, parameters, operating systems and software, creating the need for teams with multidisciplinary expertise and different skills, from IT to architecture, design, material engineering, and mathematics, among others The papers grew out of a Lisbon symposium hosted by the ISCTE-Instituto Universitario de Lisboa entitled “Digital Fabrication – A State of the Art”. The issue is completed with four other research papers which address different mathematical instruments applied to architecture, including geometric tracing system...

  3. Becoming digital

    DEFF Research Database (Denmark)

    Pors, Anja Svejgaard

    2015-01-01

    . Originality/value: The study contributes to ethnographic research in public administration by combining two separate subfields, e-government and street-level bureaucracy, to discern recent transformations in public service delivery. In the digital era, tasks, control and equality are distributed in ways......The purpose of this paper is to examine the impact of e-government reforms on street-level bureaucrats’ professionalism and relation to citizens, thus demonstrating how the bureaucratic encounter unfolds in the digital era. Design/methodology/approach: The paper is based on an ethnographic study....... An ethnographic account of how digital reforms are implemented in practice shows how street-level bureaucrat’s classic tasks such as specialized casework are being reconfigured into educational tasks that promote the idea of “becoming digital”. In the paper, the author argues that the work of “becoming digital...

  4. Comparison of Selenium Treatments of Crops in the Field

    DEFF Research Database (Denmark)

    Nielsen, Gunnar Gissel

    1986-01-01

    Field experiments with spring and winter barley and ryegrass were carried out to compare the effect of fertilizers enriched with selenate or selenite with foliar application on the selenium (Se) concentrations in the crops. Application of about 20 g Se/ha given as selenate or about 100 g as selen......Field experiments with spring and winter barley and ryegrass were carried out to compare the effect of fertilizers enriched with selenate or selenite with foliar application on the selenium (Se) concentrations in the crops. Application of about 20 g Se/ha given as selenate or about 100 g...... as selenite in a PK fertilizer and about 5 g Se/ha sprayed on the plants increased the Se-concentrations from insufficient levels to levels that met the animal nutritional requirement. Ryegrass obtained sufficient Se concentrations at lower levels of added Se than did the barley. Toxic concentrations did...

  5. Sources of particulate selenium in the Baltic Sea atmosphere

    Directory of Open Access Journals (Sweden)

    Beata Dudziñska-Huczuk

    2000-09-01

    Full Text Available To determine the atmospheric concentrations and size distributions of particulate selenium (Se, aerosols were collected by air filtration and impactor sampling at the Kap Arkona coastal weather station on the Island of Rügen. Total reflection X-ray fluorescence analysis was used to determine Se and numerous other elements as well. The dependence of the Se concentration on the wind direction and the results of a regression analysis indicated that Se associated with sub-micron particles is mainly derived from anthropogenic sources. The pronounced relationship between Se and Cu indicated that copper smelting is a major source of atmospheric selenium. A marine Se contribution was identified for particles larger than 2 µm.

  6. Digital Bangladesh

    OpenAIRE

    Masudul Alam Choudhury

    2013-01-01

    The present fever to launch an extensive digitalization program is sweeping the Bangladesh political, business, and elitist minds. In the face of an overarching outlook of sustainable development the Bangladesh digitalization program runs into some grave questions. The paper points out that ethics as a strongly endogenous force in development is indispensable to keep in view the simultaneity of attaining growth and social justice. These targets are variously manifested in different sectors an...

  7. Digital Leadership

    OpenAIRE

    Zupanzic, Tadeja; Verbeke, Johan; Achten, Henri; Herneoja, Aulikki

    2016-01-01

    Leadership is an important quality in organisations. Leadership is needed to introduce change and innovation. In our opinion, in architectural and design practices, the role of leadership has not yet been sufficiently studied, especially when it comes to the role of digital tools and media. With this paper, we intend to initiate a discussion in the eCAADe community to reflect and develop ideas in order to develop digital leadership skills amongst the membership. This paper introduces some imp...

  8. Protective effect of pre-supplementation with selenium on cadmium ...

    African Journals Online (AJOL)

    The effect of the antioxidant nutrient selenium, Se, on biologic response to cadmium-induced oxidative cytotoxicity was investigated in rats pretreated with Se prior to exposure to mild doses of Cd. Male wistar strain rats (200-250 g b.wt) were exposed to a single daily oral dose of cadmium (3 mg CdCl2/kg) in drinking water ...

  9. Selenium and Chronic Diseases: A Nutritional Genomics Perspective

    OpenAIRE

    Catherine Méplan

    2015-01-01

    Mechanistic data have revealed a key role for selenium (Se) and selenoproteins in biological pathways known to be altered in multifactorial diseases, such as cellular maintenance, response to oxidative stress and correct protein folding. Although epidemiological studies indicate that low Se intake is linked to increased risk for various chronic diseases, supplementation trials have given confusing outcomes, suggesting that additional genetic factors could affect the relationship between Se an...

  10. Glassy selenium at high pressure: Le Chatelier's principle still works

    Science.gov (United States)

    Brazhkin, V. V.; Tsiok, O. B.

    2017-10-01

    Selenium is the only easily vitrified elementary substance. Numerous experimental studies of glassy Se (g -Se) at high pressures show a large spread in the data on the compressibility and electrical resistivity of g -Se. Furthermore, H. Liu et al. [Proc. Natl. Acad. Sci. USA 105, 13229 (2008), 10.1073/pnas.0806857105] have arrived at the surprising conclusion that the volume of glass increases during pressure-induced crystallization. We have performed high-precision measurements of the specific volume and electrical resistivity of glassy selenium (g -Se) at high hydrostatic pressures up to 9 GPa. The measured bulk modulus at normal pressure is B =(9.0 5 ±0.15 ) GPa and its pressure derivative is BP'=6.4 ±0.2 . In the pressure range P <3 GPa, glassy selenium has an anomalously large negative second derivative of the bulk modulus. The electrical resistivity of g -Se decreases almost exponentially with increasing pressure and reaches 20 Ω cm at a pressure of 8.75 GPa. The inelastic behavior and weak relaxation of the volume for g -Se begin at pressures above 3.5 GPa; the volume and logarithm of the electrical resistivity relax significantly (logarithmically with the time) at pressures above 8 GPa. Bulk measurements certainly indicate that the volume of g -Se glass in the crystallization pressure range is larger than the volumes of both appearing crystalline phases (by 2% and 4%). Therefore, the "volume expansion phenomenon" suggested in [H. Liu et al., Proc. Natl. Acad. Sci. USA 105, 13229 (2008), 10.1073/pnas.0806857105] is not observed, and the pressure-induced crystallization of glassy selenium is consistent with the laws of thermodynamics.

  11. Copper, selenium and zinc content of canned and noncanned ...

    African Journals Online (AJOL)

    Abstract. The levels of copper, selenium and zinc in beverages purchased in Nigeria were studied. Fifty samples of these beverages were digested in nitric acid and were analyzed using the Atomic Absorption Spectrophotometer (AAS). The zinc levels ranged from 0.0 - 1.34 mg/L for the canned and 0.01 - 1.11 mg/L for the ...

  12. Selenium supplementation restores the antioxidative capacity and prevents cell damage in bone marrow stromal cells in vitro

    DEFF Research Database (Denmark)

    Ebert, Regina; Ulmer, Matthias; Zeck, Sabine

    2006-01-01

    signaling, cumulative cell damage, senescence, and tumor development. Selenium-dependent (glutathione peroxidases [GPxs] and thioredoxin reductases [TrxRs]) and selenium-independent (superoxide dismutases [SODs] and catalase [CAT]) enzyme systems regulate cellular ROS steady state levels. SODs process...

  13. Plasma selenium concentrations are sufficient and associated with protease inhibitor use in treated HIV-infected adults

    Science.gov (United States)

    Background: Selenium (Se) is an essential constituent of selenoproteins which play significant roles in antioxidant defense and inflammatory cascades. Selenium deficiency is associated with disease states characterized by inflammation including cardiovascular disease (CVD). While HIV infection has b...

  14. Immune response of stressed calves deficient in selenium

    Energy Technology Data Exchange (ETDEWEB)

    Reffett, J.K.; Spears, J.W.; Brown, T.T. Jr.

    1986-03-01

    A selenium deficiency in animals may reduce their metabolic and immunological response to stress. Twenty beef calves (212 kg) from a common origin were weaned, transported 322 km and then allotted to one of the following treatments: (1) control, (2) control/stress, (3) selenium (Se) and (4) Se/stress. Previous Se nutriture was controlled as dams of control calves were fed diets marginally deficient in Se (.04-.05 ppm) while dams of Se treatment calves received supplemental Se. Calves in the Se treatments received 0.1 ppm supplemental Se during the study. All animals were subjected to the stresses of weaning and transport. Calves allotted to the stress treatments were also given intratracheal inoculations of Pasteurella hemolytica on day 3 after weaning and transport. Serum immunoglobulins (IgG and IgM) and antibody titers to P. hemolytica were measured on days 0, 1, 3, 7, 10, 17 of the study. Serum IgG was lower for calves in the stress treatments on days 7 and 17. Selenium supplemented calves had higher serum IgM concentrations on day 17. Antibody titers to P. hemolytica were higher on days 10 and 17 for calves in the stress treatments. Calves in the Se treatments had lower antibody titers than controls on days 7, 10 and 17. These results indicate that a marginal Se deficiency can affect the immunological response to stress.

  15. Environmental arsenic exposure, selenium and sputum alpha-1 antitrypsin

    DEFF Research Database (Denmark)

    Burgess, Jefferey L; Kurzius-Spencer, Margaret; Poplin, Gerald S

    2014-01-01

    Exposure to arsenic in drinking water is associated with increased respiratory disease. Alpha-1 antitrypsin (AAT) protects the lung against tissue destruction. The objective of this study was to determine whether arsenic exposure is associated with changes in airway AAT concentration and whether...... this relationship is modified by selenium. A total of 55 subjects were evaluated in Ajo and Tucson, Arizona. Tap water and first morning void urine were analyzed for arsenic species, induced sputum for AAT and toenails for selenium and arsenic. Household tap-water arsenic, toenail arsenic and urinary inorganic...... arsenic and metabolites were significantly higher in Ajo (20.6±3.5 μg/l, 0.54±0.77 μg/g and 27.7±21.2 μg/l, respectively) than in Tucson (3.9±2.5 μg/l, 0.16±0.20 μg/g and 13.0±13.8 μg/l, respectively). In multivariable models, urinary monomethylarsonic acid (MMA) was negatively, and toenail selenium...

  16. Thiolated eggshell membranes sorb and speciate inorganic selenium.

    Science.gov (United States)

    Yang, Ting; Chen, Ming-Li; Hu, Xian-Wei; Wang, Zhao-Wen; Wang, Jian-Hua; Dasgupta, Purnendu K

    2011-01-07

    Eggshell membranes (ESMs) provide a unique, disulfide bond-rich surface. Thioglycolate reduction was used to generate thiol (-SH) groups on the ESM surface by S-S bond cleavage. The thiol-bearing ESMs (TESMs) were characterized by scanning electron microscopy and Raman spectroscopy. The fibrous network structure of the ESM is retained in the TESMs. TESMs adsorb both Se(IV) and Se(VI) but by different mechanisms: Se(VI) is retained reversibly, possibly via ionic interactions, while Se(IV) is reduced to Se(0) and deposited. We thus demonstrate speciation of selenium species, by using samples (a) as such and after prior oxidation to Se(VI), (b) preconcentration on a TESM microcolumn, (c) elution by 0.5 M HNO(3) that only elutes Se(VI) and (d) detection by graphite furnace atomic absorption spectrometry (GFAAS). The Se(IV) amount is determined by difference. For a 1.0 mL sample, the enrichment factor was 17.2, the S/N = 3 detection limit was 0.06 μg L(-1) and the precision was 3.3% at 0.50 μg L(-1). The linear range was 0.25-2.50 μg L(-1). The procedure was validated by analyzing selenium in certified reference materials of human hair (GBW 09101) and rice (GBW 10010). We further demonstrate utility by speciation of inorganic selenium in a series of water samples.

  17. Traveling cluster approximation for uncorrelated amorphous systems

    International Nuclear Information System (INIS)

    Kaplan, T.; Sen, A.K.; Gray, L.J.; Mills, R.

    1985-01-01

    In this paper, the authors apply the TCA concepts to spatially disordered, uncorrelated systems (e.g., fluids or amorphous metals without short-range order). This is the first approximation scheme for amorphous systems that takes cluster effects into account while preserving the Herglotz property for any amount of disorder. They have performed some computer calculations for the pair TCA, for the model case of delta-function potentials on a one-dimensional random chain. These results are compared with exact calculations (which, in principle, taken into account all cluster effects) and with the CPA, which is the single-site TCA. The density of states for the pair TCA clearly shows some improvement over the CPA, and yet, apparently, the pair approximation distorts some of the features of the exact results. They conclude that the effects of large clusters are much more important in an uncorrelated liquid metal than in a substitutional alloy. As a result, the pair TCA, which does quite a nice job for alloys, is not adequate for the liquid. Larger clusters must be treated exactly, and therefore an n-TCA with n > 2 must be used

  18. Memristive effects in oxygenated amorphous carbon nanodevices

    Science.gov (United States)

    Bachmann, T. A.; Koelmans, W. W.; Jonnalagadda, V. P.; Le Gallo, M.; Santini, C. A.; Sebastian, A.; Eleftheriou, E.; Craciun, M. F.; Wright, C. D.

    2018-01-01

    Computing with resistive-switching (memristive) memory devices has shown much recent progress and offers an attractive route to circumvent the von-Neumann bottleneck, i.e. the separation of processing and memory, which limits the performance of conventional computer architectures. Due to their good scalability and nanosecond switching speeds, carbon-based resistive-switching memory devices could play an important role in this respect. However, devices based on elemental carbon, such as tetrahedral amorphous carbon or ta-C, typically suffer from a low cycling endurance. A material that has proven to be capable of combining the advantages of elemental carbon-based memories with simple fabrication methods and good endurance performance for binary memory applications is oxygenated amorphous carbon, or a-CO x . Here, we examine the memristive capabilities of nanoscale a-CO x devices, in particular their ability to provide the multilevel and accumulation properties that underpin computing type applications. We show the successful operation of nanoscale a-CO x memory cells for both the storage of multilevel states (here 3-level) and for the provision of an arithmetic accumulator. We implement a base-16, or hexadecimal, accumulator and show how such a device can carry out hexadecimal arithmetic and simultaneously store the computed result in the self-same a-CO x cell, all using fast (sub-10 ns) and low-energy (sub-pJ) input pulses.

  19. Removal of Selenium and Nitrate in Groundwater Using Organic Carbon-Based Reactive Mixtures

    Science.gov (United States)

    An, Hyeonsil; Jeen, Sung-Wook

    2016-04-01

    Treatment of selenium and nitrate in groundwater was evaluated through column experiments. Four columns consisting of reactive mixtures, either organic carbon-limestone (OC-LS) or organic carbon-zero valent iron (OC-ZVI), were used to determine the removal efficiency of selenium with different concentrations of nitrate. The source waters were collected from a mine site in Korea or were prepared artificially based on the mine drainage water or deionized water, followed by spiking of elevated concentrations of Se (40 mg/L) and nitrate (100 or 10 mg/L as NO3-N). The results for the aqueous chemistry showed that selenium and nitrate were effectively removed both in the mine drainage water and deionized water-based artificial input solution. However, the removal of selenium was delayed when selenium and nitrate coexisted in the OC-LS columns. The removal of selenium was not significant when the influent nitrate concentration was 100 mg/L as NO3-N, while most of nitrate was gradually removed within the columns. In contrast, 94% of selenium was removed when the influent nitrate concentration was reduced to 10 mg/L as NO3-N. In the OC-ZVI column, selenium and nitrate was removed almost simultaneously and completely even with the high nitrate concentration; however, a high concentration of ammonia was produced as a by-product of abiotic reaction between ZVI and nitrate. The elemental analysis for the solid samples after the termination of the experiments showed that selenium was accumulated in the reactive materials where removal of aqueous-phase selenium mostly occurred. The X-ray absorption near-edge structure (XANES) study indicated that selenium existed in the forms of SeS2 and Se(0) in the OC-LS column, while selenium was present in the forms of FeSe, SeS2 and absorbed Se(IV) in the OC-ZVI column. This study shows that OC-based reactive mixtures have an ability to remove selenium and nitrate in groundwater. However, the removal of selenium was influenced by the high

  20. Mobilization of selenium from the Mancos Shale and associated soils in the lower Uncompahgre River Basin, Colorado

    Science.gov (United States)

    Mast, M. Alisa; Mills, Taylor J.; Paschke, Suzanne S.; Keith, Gabrielle; Linard, Joshua I.

    2014-01-01

    This study investigates processes controlling mobilization of selenium in the lower part of the Uncompahgre River Basin in western Colorado. Selenium occurs naturally in the underlying Mancos Shale and is leached to groundwater and surface water by limited natural runoff, agricultural and domestic irrigation, and leakage from irrigation canals. Soil and sediment samples from the study area were tested using sequential extractions to identify the forms of selenium present in solid phases. Selenium speciation was characterized for nonirrigated and irrigated soils from an agricultural site and sediments from a wetland formed by a leaking canal. In nonirrigated areas, selenium was present in highly soluble sodium salts and gypsum. In irrigated soils, soluble forms of selenium were depleted and most selenium was associated with organic matter that was stable under near-surface weathering conditions. Laboratory leaching experiments and geochemical modeling confirm that selenium primarily is released to groundwater and surface water by dissolution of highly soluble selenium-bearing salts and gypsum present in soils and bedrock. Rates of selenium dissolution determined from column leachate experiments indicate that selenium is released most rapidly when water is applied to previously nonirrigated soils and sediment. High concentrations of extractable nitrate also were found in nonirrigated soils and bedrock that appear to be partially derived from weathered organic matter from the shale rather than from agricultural sources. Once selenium is mobilized, dissolved nitrate derived from natural sources appears to inhibit the reduction of dissolved selenium leading to elevated concentrations of selenium in groundwater. A conceptual model of selenium weathering is presented and used to explain seasonal variations in the surface-water chemistry of Loutzenhizer Arroyo, a major tributary contributor of selenium to the lower Uncompahgre River.

  1. Cross sectional study of serum selenium concentration and esophageal squamous dysplasia in western Kenya.

    Science.gov (United States)

    Pritchett, Natalie R; Burgert, Stephen L; Murphy, Gwen A; Brockman, John D; White, Russell E; Lando, Justus; Chepkwony, Robert; Topazian, Mark D; Abnet, Christian C; Dawsey, Sanford M; Mwachiro, Michael M

    2017-12-08

    Low serum selenium status has been associated with increased risk of esophageal squamous cell carcinoma (ESCC). East Africa is a region of high ESCC incidence and is known to have low soil selenium levels, but this association has not previously been evaluated. In this study we assessed the association of serum selenium concentration and the prevalence of esophageal squamous dysplasia (ESD), the precursor lesion of ESCC, in a cross-sectional study of subjects from Bomet, Kenya. 294 asymptomatic adult residents of Bomet, Kenya completed questionnaires and underwent endoscopy with Lugol's iodine staining and biopsy for detection of ESD. Serum selenium concentrations were measured by instrumental neutron activation analysis. Odds ratios (OR) and confidence intervals (95% CI) for associations between serum selenium and ESD were calculated using unconditional logistic regression. The mean serum selenium concentration was 85.5 (±28.3) μg/L. Forty-two ESD cases were identified (14% of those screened), including 5 (12%) in selenium quartile 1 (Q1), 5 (12%) in Q2, 15 (36%) in Q3, and 17 (40%) in Q4. Higher serum selenium was associated with prevalence of ESD (Q4 vs Q1: OR: 3.03; 95% CI: 1.05-8.74) and this association remained after adjusting for potential confounders (Q4 vs Q1: OR: 3.87; 95% CI: 1.06-14.19). This is the first study to evaluate the association of serum selenium concentration and esophageal squamous dysplasia in an African population at high risk for ESCC. We found a positive association between higher serum selenium concentration and prevalence of ESD, an association contrary to our original hypothesis. Further work is needed to better understand the role of selenium in the etiology of ESCC in this region, and to develop effective ESCC prevention and control strategies.

  2. Selenium content in the blood serum and urine of ewes receiving selenium-enriched unicellular alga Chlorella

    Czech Academy of Sciences Publication Activity Database

    Trávníček, J.; Písek, I.; Herzig, I.; Doucha, Jiří; Kvíčala, J.; Kroupová, V.; Rodinová, H.

    2007-01-01

    Roč. 52, - (2007), s. 42-48 ISSN 0375-8427 Grant - others:GA ČR(CZ) GD523/03/H076 Program:GD Institutional research plan: CEZ:AV0Z50200510 Source of funding: V - iné verejné zdroje Keywords : sodium selenite * organically bound selenium * ewes Subject RIV: EE - Microbiology, Virology Impact factor: 0.645, year: 2007

  3. Extracellular synthesis of Selenium nanoparticles from an Actinomycetes Streptomyces griseoruber and evaluation of its cytotoxicity on HT-29 cell line.

    Science.gov (United States)

    Ranjitha, V R; Vittal, Ravishankar Rai

    2017-11-13

    In the present study, the extracellular synthesis of Selenium nanoparticles (SeNPs) was carried out by using culture supernatant of Streptomyces griseoruber, an Actinomycetes member isolated from the soil. Bioreduction of SeNPs was confirmed by UV-Visible spectrophotometer that showed the peak at 575 nm. XRD pattern confirmed the non-crystalline or amorphous nature of the synthesised SeNPs. FTIR spectra revealed the possible functional group that is responsible for mediating the SeNPs formation. Size and distribution of the biosynthesised SeNPs were analysed by HR-TEM that showed the formation of particle size in the range of 100-250nm. The synthesised SeNPs showed good cytotoxic activity against HT-29 cell lines where apoptosis was studied by different staining procedures. The study reports for the first time, the rapid and eco-friendly synthesis of SeNPs from Streptomyces griseoruber and opens up a new possibility of commercially producing the SeNPs from biorenewable source as a natural chemotherapeutic compound. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. Role of selenium toxicity and oxidative stress in aquatic birds

    Science.gov (United States)

    Hoffman, D.J.

    2002-01-01

    Adverse effects of selenium (Se) in wild aquatic birds have been documented as a consequence of pollution of the aquatic environment by subsurface agricultural drainwater and other sources. These effects include mortality, impaired reproduction with teratogenesis, reduced growth, histopathological lesions and alterations in hepatic glutathione metabolism. A review is provided, relating adverse biological effects of Se in aquatic birds to altered glutathione metabolism and oxidative stress. Laboratory studies, mainly with an organic form of Se, selenomethionine, have revealed oxidative stress in different stages of the mallard (Anas platyrhynchos) life cycle. As dietary and tissue concentrations of Se increase, increases in plasma and hepatic GSH peroxidase activities occur, followed by dose-dependent increases in the ratio of hepatic oxidized to reduced glutathione (GSSG:GSH) and ultimately hepatic lipid peroxidation measured as an increase in thiobarbituric acid reactive substances (TBARS). One or more of these oxidative effects were associated with teratogenesis (4.6 ppm wet weight Se in eggs), reduced growth in ducklings (15 ppm Se in liver), diminished immune function (5 ppm Se in liver) and histopathological lesions (29 ppm Se in liver) in adults. Manifestations of Serelated effects on glutathione metabolism were also apparent in field studies in seven species of aquatic birds. Reduced growth and possibly immune function but increased liver:body weight and hepatic GSSG:GSH ratios were apparent in American avocet (Recurvirostra americana) hatchlings from eggs containing 9 ppm Se. In blacknecked stilts (Himantopus mexicanus), which contained somewhat lower Se concentrations, a decrease in hepatic GSH was apparent with few other effects. In adult American coots (Fulica americana), signs of Se toxicosis included emaciation, abnormal feather loss and histopathological lesions. Mean liver concentrations of 28 ppm Se (ww) in the coots were associated with elevated

  5. 78 FR 22442 - Infant Formula: The Addition of Minimum and Maximum Levels of Selenium to Infant Formula and...

    Science.gov (United States)

    2013-04-16

    ... children, has been linked to selenium deficiency. Keshan disease occurs in areas of China where the population has severe selenium deficiency. Chronic selenium toxicity (selenosis) has also been observed in... adult values on the basis of body weight and with a factor allowed for growth (Ref. 2). Although...

  6. Determination of total selenium and Se-77 in isotopically enriched human samples by ICP-dynamic reaction cell-MS

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt; Bügel, Susanne H.

    2003-01-01

    and the digested faecal samples were diluted using an aqueous diluent containing 0.5% Triton X-100, 2% nitric acid and 3% methanol. Selenium was detected as Se-76, Se-77 and Se-80 by ICP- DRC- MS. Selenium originating from the natural isotope abundance yeast and other selenium sources from the diet was determined...

  7. Uptake and specification of selenium in garlic cultivated in soil amended with symbiotic fungi (mycorrhiza) and selenate

    NARCIS (Netherlands)

    Larsen, E.H.; Lobinski, R.; Burger-Meijer, K.; Hansen, M.; Ruzik, R.; Mazurowska, L.; Rasmussen, P.H.; Sloth, J.J.; Scholten, O.E.; Kik, C.

    2006-01-01

    The scope of the work was to investigate the influence of selenate fertilisation and the addition of symbiotic fungi (mycorrhiza) to soil on selenium and selenium species concentrations in garlic. The selenium species were extracted from garlic cultivated in experimental plots by proteolytic

  8. Recent advances in co-amorphous drug formulations

    DEFF Research Database (Denmark)

    Dengale, Swapnil Jayant; Grohganz, Holger; Rades, Thomas

    2016-01-01

    Co-amorphous drug delivery systems have recently gained considerable interest in the pharmaceutical field because of their potential to improve oral bioavailability of poorly water-soluble drugs through drug dissolution enhancement as a result of the amorphous nature of the material. A co...

  9. Quantifying Nanoscale Order in Amorphous Materials via Fluctuation Electron Microscopy

    Science.gov (United States)

    Bogle, Stephanie Nicole

    2009-01-01

    Fluctuation electron microscopy (FEM) has been used to study the nanoscale order in various amorphous materials. The method is explicitly sensitive to 3- and 4-body atomic correlation functions in amorphous materials; this is sufficient to establish the existence of structural order on the nanoscale, even when the radial distribution function…

  10. CONDUCTION MECHANISM IN AMORPHOUS As2S3

    African Journals Online (AJOL)

    User

    port measurements in disordered semiconduc- tors and .... 2, with T0 = Eg/2. Eg is the mobility gap and has the same value (2.15 Ev) over the whole measured temperature range. This indicates that the conduction in amorphous As2S3 is intrinsic ... 2 : lnρ as a function of reciprocal temperature for amorphous As2S3. 15. 17.

  11. Amorphous Computing: A Research Agenda for the Near Future

    Czech Academy of Sciences Publication Activity Database

    Wiedermann, Jiří

    2012-01-01

    Roč. 11, č. 1 (2012), s. 59-63 ISSN 1567-7818 R&D Projects: GA ČR GAP202/10/1333 Institutional research plan: CEZ:AV0Z10300504 Keywords : amorphous computing * nano-machines * flying amorphous computer Subject RIV: IN - Informatics, Computer Science Impact factor: 0.683, year: 2012

  12. A beam position monitor using an amorphous magnetic core

    International Nuclear Information System (INIS)

    Kobayashi, Toshiaki; Ueda, Toru; Yoshida, Yoichi; Kozawa, Takahiro; Uesaka, Mitsuru; Miya, Kenzo; Tagawa, Seiichi; Kobayashi, Hitoshi.

    1994-01-01

    A beam position monitor for an electron accelerator has been developed by using an amorphous magnetic core. The position is detected by the difference of leakage inductances of four pickup coils wound on the amorphous magnetic core. The accuracy of the beam position monitor is less than 1 mm for the various electron pulses from nanosecond to microsecond. (author)

  13. Phase transformations of amorphous semiconductor alloys under high pressures

    CERN Document Server

    Antonov, V E; Fedotov, V K; Harkunov, A I; Ponyatovsky, E G

    2002-01-01

    The paper reviews the results of experimental studies and thermodynamical modelling of metastable T-P diagrams of initially amorphous GaSb-Ge and Zn-Sb alloys which provide a new insight into the problem of pressure-induced amorphization.

  14. Prenatal toxicity of synthetic amorphous silica nanomaterial in rats

    NARCIS (Netherlands)

    Hofmanna, T.; Schneider, S.; Wolterbeek, A.; Sandt, H. van de; Landsiedel, R.; Ravenzwaay, B. van

    2015-01-01

    Synthetic amorphous silica is a nanostructured material, which is produced and used in a wide variety of technological applications and consumer products. No regulatory prenatal toxicity studies with this substance were reported yet. Therefore, synthetic amorphous silica was tested for prenatal

  15. Calorimetric studies of non-isothermal crystallization in amorphous

    Indian Academy of Sciences (India)

    Administrator

    The applicability of Meyer–Neldel relation between the pre-exponential factor and activation energy of non-isothermal crystallization for amorphous alloys of Cu–Ti system was verified. Keywords. Amorphous materials; differential scanning calorimetry (DSC); phase transitions. 1. Introduction. There is a significant attention ...

  16. Devitrification of rapidly quenched Al–Cu–Ti amorphous alloys

    Indian Academy of Sciences (India)

    Unknown

    spinning, the entire apparatus was ... The crystallization behaviour of these amorphous alloys has been studied using DSC 2910 (TA ... Thus the change in the structure of amorphous Al50Cu45Ti5 and Al45Cu45Ti10 alloys may be summarized as ...

  17. Amorphization kinetics of Zr3Fe under electron irradiation

    International Nuclear Information System (INIS)

    Motta, A.T.; Howe, L.M.; Okamoto, P.R.

    1992-10-01

    0.9 MeV electron irradiations were performed at 28--220 K in a high-voltage electron microscope (HVEM). By measuring onset, spread and final size of the amorphous region, factoring in the Guassian distribution of the beam, a kinetic description of the amorphization in terms of dose, dose rate and temperature was obtained. The critical temperature for amorphization by electron irradiation was found to be ∼220 K, compared to 570--625 K for 40 Ar ion irradiation. Also, the dose-to-amorphization increased exponentially with temperature. Results indicated that the rate of growth of the amorphous region under the electron beam decreased with increasing temperature and the does-to-amorphization decreased with increasing dose rate. The size of the amorphous region saturated after a region dose, the final size decreasing with increasing temperature, and it was argued that this is related to the existence of a critical dose rate, which increased with temperature, below which no amorphization occurred. The above observations can be understood in the framework of the kinetics of damage accumulation under irradiation

  18. Modeling SiC swelling under irradiation: Influence of amorphization

    CERN Document Server

    Romano, A; Defranceschi, M; Yip, S

    2003-01-01

    Irradiation-induced swelling of SiC is investigated using a molecular dynamics simulation-based methodology. To mimic the effect of heavy ion irradiation extended amorphous areas of various sizes are introduced in a crystalline SiC sample, and the resulting configurations are relaxed using molecular dynamics at constant pressure. Simulation results compare very well with data from existing ion implantation experiments. Analysis of the relaxed configurations shows very clearly that SiC swelling does not scale linearly with the amorphous fraction introduced. Two swelling regimes are observed depending on the size of the initial amorphous area: for small amorphous zones swelling scales like the amorphous fraction to the power 2/3, while for larger areas it scales like the amorphous fraction to the powers 2/3 and 4/3. Similar dependences on the amorphous fraction are obtained for the number of homonuclear bonds present in the initial amorphous volume and for the number of short bonds created at the interface betw...

  19. Daily Dietary Selenium Intake in a High Selenium Area of Enshi, China

    Directory of Open Access Journals (Sweden)

    Xuebin Yin

    2013-03-01

    Full Text Available Enshi is a high selenium (Se region in Hubei, China, where human selenosis was observed between 1958 and 1963. This study investigated the daily dietary Se intake of residents in Shadi, a town located 72 km northeast of Enshi City, to assess the risk of human selenosis in the high Se area. Foods consumed typically by the local residents and their hair samples were analyzed for total Se concentration. Concentrations of Se in different diet categories were as follows: cereals: 0.96 ± 0.90 mg kg−1 DW in rice and 0.43 ± 0.55 mg kg−1 DW in corn; tuber: 0.28 ± 0.56 mg kg−1 in potato and 0.36 ± 0.12 mg kg−1 in sweet potato; vegetables: ranging from 0.23 ± 1.00 mg kg−1 in carrot to 1.57 ± 1.06 mg kg−1 in kidney bean; animal proteins: 1.99 ± 1.11 mg kg−1 in chicken and egg. Based on the food Se concentrations and the daily per-capita consumption, the estimated daily Se intake in Shadi was 550 ± 307 µg per capita. Moreover, the Se concentrations in the hairs of local adult residents were 3.13 ± 1.91 mg kg−1 (n = 122 and 2.21 ± 1.14 mg kg−1 (n = 122 for females and males, respectively, suggesting that females might be exposed to higher levels of Se from daily cooking. Although there was no human selenosis occurrence in recent years, the high level of the daily Se intake suggested that the potential risk of selenosis for local residents, especially females, might be a matter of concern.

  20. Digital evidence

    Directory of Open Access Journals (Sweden)

    Lukić Tatjana

    2012-01-01

    Full Text Available Although computer makes human activities faster and easier, innovating and creating new forms of work and other kinds of activities, it also influenced the criminal activity. The development of information technology directly affects the development of computer forensics without which, it can not even imagine the discovering and proving the computer offences and apprehending the perpetrator. Information technology and computer forensic allows us to detect and prove the crimes committed by computer and capture the perpetrators. Computer forensics is a type of forensics which can be defined as a process of collecting, preserving, analyzing and presenting digital evidence in court proceedings. Bearing in mind, that combat against crime, in which computers appear as an asset or object of the offense, requires knowledge of digital evidence as well as specific rules and procedures, the author in this article specifically addresses the issues of digital evidence, forensic (computer investigation, specific rules and procedures for detecting, fixing and collecting digital evidence and use of this type of evidence in criminal proceedings. The author also delas with international standards regarding digital evidence and cyber-space investigation.