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Amorphous selenium

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https://www.readbyqxmd.com/read/28274870/construction-of-a-cordyceps-sinensis-exopolysaccharide-conjugated-selenium-nanoparticles-and-enhancement-of-their-antioxidant-activities
#1
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
https://www.readbyqxmd.com/read/28131038/microbial-selenium-sulfide-reduction-for-selenium-recovery-from-wastewater
#2
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
https://www.readbyqxmd.com/read/28047248/tu-fg-209-01-a-model-of-noise-anisotropy-in-amorphous-selenium-digital-detectors
#3
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
https://www.readbyqxmd.com/read/28046344/mo-ab-bra-07-low-dose-imaging-with-avalanche-amorphous-selenium-flat-panel-imager
#4
J Scheuermann, A Howansky, A Goldan, S Leveille, O Tousignant, K Tanioka, W Zhao
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...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28044397/selenium-iv-vi-reduction-and-tolerance-by-fungi-in-an-oxic-environment
#5
C E Rosenfeld, J A Kenyon, B R James, C M Santelli
Microbial processes are known to mediate selenium (Se) oxidation-reduction reactions, strongly influencing Se speciation, bioavailability, and transport throughout the environment. While these processes have commonly been studied in anaerobic bacteria, the role that aerobic fungi play in Se redox reactions could be important for Se-rich soil systems, dominated by microbial activity. We quantified fungal growth, aerobic Se(IV, VI) reduction, and Se immobilization and volatilization in the presence of six, metal-tolerant Ascomycete fungi...
May 2017: Geobiology
https://www.readbyqxmd.com/read/27939658/solution-and-surface-chemistry-of-the-se-iv-fe-0-reactions-effect-of-initial-solution-ph
#6
Xuefen Xia, Lan Ling, Wei-Xian Zhang
Aspects of solution and solid-phase reactions between selenite (Se(IV)) and nanoscale zero-valent iron (nZVI) were investigated. Experimental results on the effects of initial solution pH, formation and evolution of nZVI corrosion products, and speciation of selenium in nZVI were presented. In general, the rate of Se(IV) removal decreases with increasing initial pH. The observed rate constants of Se(IV) removal decreased from 0.3530 to 0.0364 min(-1) as pH increased from 4.0 to 10.0. Composition and morphology of nZVI corrosion products and selenium species were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS)...
February 2017: Chemosphere
https://www.readbyqxmd.com/read/27895876/assessment-of-mean-glandular-dose-in-mammography-system-with-different-anode-filter-combinations-using-mcnp-code
#7
Lida Gholamkar, Ali Asghar Mowlavi, Mahdi Sadeghi, Mitra Athari
BACKGROUND: X-ray mammography is one of the general methods for early detection of breast cancer. Since glandular tissue in the breast is sensitive to radiation and it increases the risk of cancer, the given dose to the patient is very important in mammography. OBJECTIVES: The aim of this study was to determine the average absorbed dose of X-ray radiation in the glandular tissue of the breast during mammography examinations as well as investigating factors that influence the mean glandular dose (MGD)...
October 2016: Iranian Journal of Radiology: a Quarterly Journal Published By the Iranian Radiological Society
https://www.readbyqxmd.com/read/27866614/in-vivo-synthesis-of-nano-selenium-by-tetrahymena-thermophila-sb210
#8
Yin-Hua Cui, Ling-Li Li, Nan-Qing Zhou, Jing-Hua Liu, Qing Huang, Hui-Juan Wang, Jie Tian, Han-Qing Yu
Nano-selenium has a great potential to be used in chemical, biological, medical and environmental fields. Biological methods for nano-selenium synthesis have attracted wide interests, because they can be operated at ambient temperature and pressure without complicated equipments. In this work, a protozoa, Tetrahymena thermophila (T. thermophila) SB210, was used to in vivo synthesize nano-selenium. The biosynthesized nano-selenium was characterized using transmission electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy...
December 2016: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/27632529/second-harmonic-generation-from-an-individual-amorphous-selenium-nanosphere
#9
C R Ma, J H Yan, Y M Wei, G W Yang
Among the numerous nonlinear optics effects, second harmonic generation (SHG) is always a hotspot and it is extensively used for optical frequency conversion, biomedical imaging, etc. However, SHG is forbidden in a medium with inversion symmetry under the electric-dipole approximation. Here, we demonstrated SHG from a single amorphous selenium (a-Se) nanosphere under near-infrared femtosecond pulse excitation. It was found that SH spectra are tunable with the size of a-Se nanospheres and the SHG efficiency of a single a-Se sphere with a diameter over 300 nm is estimated at 10(-8)...
October 21, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27584907/correlative-light-and-electron-microscopy-using-quantum-dot-nanoparticles
#10
Murray C Killingsworth, Yuri V Bobryshev
A method is described whereby quantum dot (QD) nanoparticles can be used for correlative immunocytochemical studies of human pathology tissue using widefield fluorescence light microscopy and transmission electron microscopy (TEM). To demonstrate the protocol we have immunolabeled ultrathin epoxy sections of human somatostatinoma tumor using a primary antibody to somatostatin, followed by a biotinylated secondary antibody and visualization with streptavidin conjugated 585 nm cadmium-selenium (CdSe) quantum dots (QDs)...
2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/27564846/electrochemistry-of-selenium-with-sodium-and-lithium-kinetics-and-reaction-mechanism
#11
Qianqian Li, Heguang Liu, Zhenpeng Yao, Jipeng Cheng, Tiehu Li, Yuan Li, Chris Wolverton, Jinsong Wu, Vinayak P Dravid
There are economic and environmental advantages by replacing Li with Na in energy storage. However, sluggishness in the charge/discharge reaction and low capacity are among the major obstacles to development of high-power sodium-ion batteries. Among the electrode materials recently developed for sodium-ion batteries, selenium shows considerable promise because of its high capacity and good cycling ability. Herein, we have investigated the mechanism and kinetics of both sodiation and lithiation reactions with selenium nanotubes, using in situ transmission electron microscopy...
September 27, 2016: ACS Nano
https://www.readbyqxmd.com/read/27514819/mitochondria-mediated-protein-regulation-mechanism-of-polymorphs-dependent-inhibition-of-nanoselenium-on-cancer-cells
#12
Ge Wang, Yuming Guo, Gai Yang, Lin Yang, Xiaoming Ma, Kui Wang, Lin Zhu, Jiaojiao Sun, Xiaobing Wang, Hua Zhang
The present study was (i) to prepare two types of selenium nanoparticles, namely an amorphous form of selenium quantum dots (A-SeQDs) and a crystalline form of selenium quantum dots (C-SeQDs); and (ii) to investigate the nano-bio interactions of A-SeQDs and C-SeQDs in MCF-7, HepG2, HeLa, NIH/3T3, L929 cells and BRL-3A cells. It was found that A-SeQDs could induce the mitochondria-mediated apoptosis, necrosis and death of cells, while C-SeQDs had much weaker effects. This polymorphs-dependent anti-proliferative activity of nano-selenium was scarcely reported...
2016: Scientific Reports
https://www.readbyqxmd.com/read/27472329/substrate-and-passivation-techniques-for-flexible-amorphous-silicon-based-x-ray-detectors
#13
Michael A Marrs, Gregory B Raupp
Flexible active matrix display technology has been adapted to create new flexible photo-sensing electronic devices, including flexible X-ray detectors. Monolithic integration of amorphous silicon (a-Si) PIN photodiodes on a flexible substrate poses significant challenges associated with the intrinsic film stress of amorphous silicon. This paper examines how altering device structuring and diode passivation layers can greatly improve the electrical performance and the mechanical reliability of the device, thereby eliminating one of the major weaknesses of a-Si PIN diodes in comparison to alternative photodetector technology, such as organic bulk heterojunction photodiodes and amorphous selenium...
2016: Sensors
https://www.readbyqxmd.com/read/27353373/biomimetic-synthesis-of-selenium-nanoparticles-by-pseudomonas-aeruginosa-atcc-27853-an-approach-for-conversion-of-selenite
#14
Aruna Jyothi Kora, Lori Rastogi
A facile and green method for the reduction of selenite was developed using a Gram-negative bacterial strain Pseudomonas aeruginosa, under aerobic conditions. During the process of bacterial conversion, the elemental selenium nanoparticles were produced. These nanoparticles were systematically characterized using various analytical techniques including UV-visible spectroscopy, XRD, Raman spectroscopy, SEM, DLS, TEM and FTIR spectroscopy techniques. The generation of selenium nanoparticles was confirmed from the appearance of red colour in the culture broth and broad absorption peaks in the UV-vis...
October 1, 2016: Journal of Environmental Management
https://www.readbyqxmd.com/read/27147084/protective-role-of-biogenic-selenium-nanoparticles-in-immunological-and-oxidative-stress-generated-by-enrofloxacin-in-broiler-chicken
#15
Shubhangi Shirsat, Ambadas Kadam, Rajaram S Mane, Vijaykumar V Jadhav, Manohar K Zate, Mu Naushad, Kwang Ho Kim
Presently most bacteria are becoming antibiotic resistant. Due to this there is a deficiency of potent antibiotics, therefore we have to preserve and improve the efficiency of existing antibiotics by mitigating the side effects. Enrofloxacin (EFX) is an important antimicrobial used in veterinary practice but it is known to exert immune suppression antioxidant stress. In the present study, we report on: (a) the biosynthesis of selenium nanoparticles (Se NPs), and (b) their protective effect in reducing adverse effects of EFX on broiler chicken...
June 7, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/27107111/biomagnetic-recovery-and-bioaccumulation-of-selenium-granules-in-magnetotactic-bacteria
#16
Masayoshi Tanaka, William Knowles, Rosemary Brown, Nicole Hondow, Atsushi Arakaki, Stephen Baldwin, Sarah Staniland, Tadashi Matsunaga
UNLABELLED: Using microorganisms to remove waste and/or neutralize pollutants from contaminated water is attracting much attention due to the environmentally friendly nature of this methodology. However, cell recovery remains a bottleneck and a considerable challenge for the development of this process. Magnetotactic bacteria are a unique group of organisms that can be manipulated by an external magnetic field due to the presence of biogenic magnetite crystals formed within their cells...
July 1, 2016: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/27038210/mercury-species-selenium-metallothioneins-and-glutathione-in-two-dolphins-from-the-southeastern-brazilian-coast-mercury-detoxification-and-physiological-differences-in-diving-capacity
#17
Helena A Kehrig, Rachel A Hauser-Davis, Tercia G Seixas, Ana Beatriz Pinheiro, Ana Paula M Di Beneditto
In the present study, the concentration of trace elements, total mercury (Hg) and selenium (Se) and mercury forms (MeHg, Hginorg and HgSe) in the vulnerable coastal dolphins Pontoporia blainvillei and Sotalia guianensis were appraised and compared, using metallothioneins (MT) and glutathione (GSH) as biomarkers for trace element exposure. The trace element concentrations varied between muscle and liver tissues, with liver of all dolphin specimens showing higher Hg and Se concentrations than those found in muscle...
June 2016: Environmental Pollution
https://www.readbyqxmd.com/read/26709976/x-ray-responsive-selenium-nanoparticles-for-enhanced-cancer-chemo-radiotherapy
#18
Bo Yu, Ting Liu, Yanxin Du, Zuandi Luo, Wenjie Zheng, Tianfeng Chen
Resistance of cancer to radiotherapy and/or chemotherapy is one of the important reasons of clinical treatment failure and recurrence. Chemoradiation is an optional method to over-coming of radioresistance and chemoresistance. Selenium nanoparticles (SeNPs) with special chemical and physical properties, has been identified as a novel nanocarrier and therapy agent with broad-spectrum anticancer activities due to generate ROS in cells. Herein, X-ray responsive selenium nanoparticles were facilely fabricated by using PEG as surface decorator and template...
March 1, 2016: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/26427022/self-catalytic-polymerization-of-a-water-soluble-selenium-polypyrrole-nanocomposite-and-its-nonlinear-optical-properties
#19
Rui Ke, Xiaomei Zhang, Shengyi Zhang, Shengli Li, Changjie Mao, Helin Niu, Jiming Song, Yupeng Tian
A facile one-step method for the synthesis of a water-soluble selenium/polypyrrole (Se/PPy) nanocomposite was developed. In the aqueous synthesis process, the pyrrole acted as a reductant for the reduction of H2SeO3, and then the elemental Se formed in situ acted as a catalyst for the polymerization of pyrrole. The characterization results show that the as-obtained composite (Se/PPy) is a spherical (Φ80 nm) product that is made up of amorphous Se particles coated by PPy layers. The formation mechanism and influence factors of the products were discussed, based on a series of experiments...
November 7, 2015: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/26371540/correlative-cryogenic-spectro-microscopy-to-investigate-selenium-bioreduction-products
#20
Sirine C Fakra, Birgit Luef, Cindy J Castelle, Sean W Mullin, Kenneth H Williams, Matthew A Marcus, Denise Schichnes, Jillian F Banfield
Accurate mapping of the composition and structure of minerals and associated biological materials is critical in geomicrobiology and environmental research. Here we developed an apparatus allowing correlation of cryogenic transmission electron microscopy (TEM) and synchrotron hard X-ray microprobe (SHXM) datasets to precisely determine the distribution, valence state and structure of selenium in biofilms sampled from a contaminated aquifer near Rifle, CO, USA. Results were replicated in the laboratory via anaerobic selenate-reducing enrichment cultures...
September 15, 2015: Environmental Science & Technology
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