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Amorphous selenium

Khaled Alkhalifah, Ajit Brindhaban
OBJECTIVE: To investigate the effect of exposure factors used in digital screening mammography on images quality of different breast compositions. MATERIAL AND METHODS: A digital mammographic unit, with Tungsten (W) as target, Rhodium (Rh) and Silver (Ag) as filters and amorphous selenium (a-Se) detectors, was used to image Computerized Imaging Reference Systems (CIRS) Model 12A phantoms of thickness 4, 5 and 6 cm. Images of each phantom were obtained using target-filter combinations of W/Rh and W/Ag, at 28, 30, and 32 kVp...
March 7, 2018: Medical Principles and Practice: International Journal of the Kuwait University, Health Science Centre
Jitao Li, Xinghua Zhu, Dingyu Yang, Peng Gu, Haihua Wu
Amorphous selenium (a-Se) thin films with a thickness of 1200 nm were successfully fabricated by thermal evaporation at a low vacuum degree of 10-2 Pa. The structural properties involving phase and morphology showed that a-Se thin films could be resistant to 60 °C in air. Also, a transformation to polycrystalline Selenium (p-Se) was shown as the annealing temperature rose to 62 °C and 65 °C, with obvious changes in color and surface morphology. Moreover, as the a-Se transformed to p-Se, the samples' transmittance decreased significantly, and the band gap declined dramatically from 2...
March 2, 2018: Materials
Sweety A Wadhwani, Utkarsha U Shedbalkar, Richa Singh, Balu A Chopade
Synthesis of nanoparticles is an enzymatic reduction process in microorganisms. In the present study, a protein, lignin peroxidase has been purified by DEAE-Cellulose anion exchange chromatography and Biogel P-150 gel filtration chromatography from the cell suspension of Acinetobacter sp. SW30 responsible for the synthesis of gold nanoparticles (AuNP) and selenium nanoparticles (SeNP). The purified fraction has a specific activity of 29.4U/mg/min with 959 fold purification. Native and SDS PAGE confirmed that purified lignin peroxidase is monomeric enzyme with 97...
April 2018: Enzyme and Microbial Technology
Anna V Tugarova, Polina V Mamchenkova, Yulia A Dyatlova, Alexander A Kamnev
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 (SeO3 2- ) reduction by the bacterium Azospirillum thiophilum (strain VKM B-2513) for the first time, using an original methodology for obtaining extracellular NPs...
March 5, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
James R Scheuermann, Adrian Howansky, Marc Hansroul, Sébastien Léveillé, Kenkichi Tanioka, Wei Zhao
PURPOSE: We present the first prototype Scintillator High-Gain Avalanche Rushing Photoconductor Active Matrix Flat Panel Imager (SHARP-AMFPI). This detector includes a layer of avalanche amorphous Selenium (a-Se) (HARP) as the photoconductor in an indirect detector to amplify the signal and reduce the effects of electronic noise to obtain quantum noise-limited images for low-dose applications. It is the first time avalanche a-Se has been used in a solid-state imaging device and poses as a possible solution to eliminate the effects of electronic noise, which is crucial for low-dose imaging performance of AMFPI...
February 2018: Medical Physics
V R Ranjitha, Ravishankar Rai Vittal
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...
November 13, 2017: Pharmaceutical Nanotechnology
Jing-Kun Yan, Wen-Yi Qiu, Yao-Yao Wang, Wen-Han Wang, Yan Yang, He-Nan Zhang
In this study, carboxylic curdlans (Cur-4, Cur-8, and Cur-24) with different molecular properties and chain conformations were used as stabilizer and capping agent to fabricate stable and water-dispersible selenium nanoparticles (SeNPs). Results showed that molecular properties and chain conformations of carboxylic curdlans remarkably influenced the size, morphology, structure, and stability of SeNPs and the carboxylic curdlan was ligated to SeNPs via OH⋯Se interaction. The as-prepared SeNPs was amorphous and showed homogeneous and monodisperse spherical structure with size of ∼50-90nm...
January 1, 2018: Carbohydrate Polymers
Zhijian Li, Haifeng Li, Huiying Hu
In this study, the removal and reduction of selenite [Se(IV)] by growing Aspergillus sp. J2 were investigated. The lag phase, growth rate and biomass of J2 was not significantly influenced by the presence of 100 mg/L Se(IV). A rapid Se(IV) removal process took place from the 3rd to the 4th day during the growth of J2. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction analyses showed that the Se(IV) did not cause any visible effects on cell morphology and the reduced amorphous elemental selenium [Se(0)] nanoparticles were mainly on the surface of the mycelial cell walls...
November 6, 2017: Biometals: An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine
O Semeniuk, O Grynko, G Juska, A Reznik
Presence of a signal lag is a bottle neck of performance for many non-crystalline materials, considered for dynamic radiation sensing. Due to inadequate lag-related temporal performance, polycrystalline layers of CdZnTe, PbI2, HgI2 and PbO are not practically utilized, despite their superior X-ray sensitivity and low production cost (even for large area detectors). In the current manuscript, we show that a technological step to replace nonhomogeneous disorder in polycrystalline PbO with homogeneous amorphous PbO structure suppresses signal lag and improves time response to X-ray irradiation...
October 16, 2017: Scientific Reports
Yong Churl Kim, Kwang Hee Kim, Dae-Yong Son, Dong-Nyuk Jeong, Ja-Young Seo, Yeong Suk Choi, In Taek Han, Sang Yoon Lee, Nam-Gyu Park
Medical X-ray imaging procedures require digital flat detectors operating at low doses to reduce radiation health risks. Solution-processed organic-inorganic hybrid perovskites have characteristics that make them good candidates for the photoconductive layer of such sensitive detectors. However, such detectors have not yet been built on thin-film transistor arrays because it has been difficult to prepare thick perovskite films (more than a few hundred micrometres) over large areas (a detector is typically 50 centimetres by 50 centimetres)...
October 4, 2017: Nature
Sweety A Wadhwani, Mahadeo Gorain, Pinaki Banerjee, Utkarsha U Shedbalkar, Richa Singh, Gopal C Kundu, Balu A Chopade
The aim of this study was to synthesize selenium nanoparticles (SeNPs) using cell suspension and total cell protein of Acinetobacter sp. SW30 and optimize its synthesis by studying the influence of physiological and physicochemical parameters. Also, we aimed to compare its anticancer activity with that of chemically synthesized SeNPs in breast cancer cells. Cell suspension of Acinetobacter sp. SW30 was exposed to various physiological and physicochemical conditions in the presence of sodium selenite to study their effects on the synthesis and morphology of SeNPs...
2017: International Journal of Nanomedicine
Jessica E Favorito, Todd P Luxton, Matthew J Eick, Paul R Grossl
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...
October 2017: Environmental Pollution
Duo Wei, Mengting Han, Lei Yu
Characterization of selenium states by (77)Se NMR is quite important to provide vital information for mechanism studies in organoselenium-catalyzed reactions. With the development of heterogeneous polymer-supported organoselenium catalysts, the solid state (77)Se NMR comes to the spotlight. It is necessary to figure out an advanced protocol that provides good quality spectra within limited time because solid state (77)Se NMR measurements are always time consuming due to the long relaxation time and the relatively low sensitivity...
July 25, 2017: Scientific Reports
Maxwell Marple, Jackson Badger, Ivan Hung, Zhehong Gan, Kirill Kovnir, Sabyasachi Sen
Amorphous selenium, owing to its tremendous technological importance and perhaps to its chemical simplicity, has been studied for nearly a century and yet an unequivocal structural description of this material remains lacking to date. The primary controversy regarding the structure of amorphous Se relates to the relative fraction of Se atoms residing in ∞1Se chains versus in Se8 rings. Herein we present the results of a two-dimensional solid-state (77) Se nuclear magnetic resonance (NMR) spectroscopic study of the chain and ring crystalline allotropes of Se as well as of amorphous Se to unequivocally demonstrate that 1) the Se8 rings and the ∞1Se chains are characterized by their unique (77) Se NMR signatures and 2) the structure of amorphous Se consists exclusively of ∞1Se chains...
June 25, 2017: Angewandte Chemie
David A Scaduto, Olivier Tousignant, Wei Zhao
PURPOSE: Dual-energy contrast-enhanced imaging is being investigated as a tool to identify and localize angiogenesis in the breast, a possible indicator of malignant tumors. This imaging technique requires that x-ray images are acquired at energies above the k-shell binding energy of an appropriate radiocontrast agent. Iodinated contrast agents are commonly used for vascular imaging, and require x-ray energies greater than 33 keV. Conventional direct conversion amorphous selenium (a-Se) flat-panel imagers for digital mammography show suboptimal absorption efficiencies at these higher energies...
August 2017: Medical Physics
Wei Yan, Yunpeng Qu, Tapajyoti Das Gupta, Arouna Darga, Dang Tùng Nguyên, Alexis Gérald Page, Mariana Rossi, Michele Ceriotti, Fabien Sorin
The recent ability to integrate semiconductor-based optoelectronic functionalities within thin fibers is opening intriguing opportunities for flexible electronics and advanced textiles. The scalable integration of high-quality semiconducting devices within functional fibers however remains a challenge. It is difficult with current strategies to combine high light absorption, good microstructure and efficient electrical contact. The growth of semiconducting nanowires is a great tool to control crystal orientation and ensure a combination of light absorption and charge extraction for efficient photodetection...
May 12, 2017: Advanced Materials
Aruna Jyothi Kora, Lori Rastogi
A biosynthetic method for the production of selenium nanoparticles under ambient temperature and pressure from sodium selenite was developed using Gram-negative bacterial strain Escherichia coli ATCC 35218. Bacteriogenic nanoparticles were methodologically characterized employing UV-vis, XRD, Raman spectroscopy, SEM, TEM, DLS and FTIR techniques. Generation of nanoparticles was visualized from the appearance of red colour in the selenite supplemented culture medium and broad absorption bands in the UV-vis. Biofabricated nanoparticles were spherical, polydisperse, ranged from 100-183 nm and the average particle size was about 155 nm...
March 2017: IET Nanobiotechnology
Yidong Xiao, Qilin Huang, Zhaomin Zheng, Han Guan, Shiyu Liu
A Cordyceps sinensis exopolysaccharide (EPS)-conjugated selenium nanoparticles (SeNPs) were successfully constructed through the reduction of SeO3(2-). The EPS-SeNPs were characterized in terms of formation, morphology, size, Se distribution and phase by UV-vis, FT-IR, transmission electron microscopy (TEM), dynamic light scattering (DLS), energy dispersive X-ray (EDX) and wide angle X-ray diffraction (WAXD) measurements. Results revealed that the SeNPs conjugated to EPS were amorphous and could be well dispersed at a size range of 80-125nm...
June 2017: International Journal of Biological Macromolecules
S P W Hageman, R D van der Weijden, A J M Stams, P van Cappellen, C J N Buisman
Microbial reduction of selenium sulfide (SeS2) is a key step in a new treatment process to recover selenium from selenate and selenite streams. In this process, selenate is first reduced to selenite, and subsequently selenite is reduced by sulfide and precipitates from the solution as SeS2. The latter is bio-reduced to elemental selenium and sulfide. Two anaerobic granular sludges (Eerbeek and Emmtec) were tested for their efficiency to reduce commercial crystalline SeS2. Emmtec sludge had the highest reducing capacity with commercial SeS2 and was therefore also used for the bioreduction of laboratory synthesized amorphous SeS2...
May 5, 2017: Journal of Hazardous Materials
R Acciavatti, A Maidment
PURPOSE: One of the main advantages of amorphous selenium (a-Se) photoconductors is high spatial resolution. It has also been shown that the noise power spectra (NPS) is effectively white (frequency-independent) at various angles of x-ray incidence. One limitation of previous studies on NPS is that the effect of digitization has not been modeled. This work demonstrates that the NPS becomes colored (frequency-dependent) once digitization is taken into account. METHODS: A mammography system is modeled by tracing rays between the focal spot and the detector...
June 2016: Medical Physics
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