Energy Technology Data Exchange (ETDEWEB)

The article deals with a novel electrochemical method of preparing long-lived silver nanoparticles suspended in aqueous solution as well as silver powders. The method does not involve the use of any chemical stabilising agents. The morphology of the silver nanoparticles obtained was studied using transmission electron microscopy, scanning electron microscopy, atomic force microscopy and dynamic light scattering measurements. Silver nanoparticles suspended in water solution that were produced by the present technique are nearly spherical and their size distribution lies in the range of 2 to 20 nm, the average size being about 7 nm. Silver nanoparticles synthesised by the proposed method were sufficiently stable for more than 7 years even under ambient conditions. Silver crystal growth on the surface of the cathode in the electrochemical process used was shown to ...

British Library Electronic Table of Contents (United Kingdom)

The formation of nanoparticles during the radiation-induced chemical reduction of silver ions, copper ions, and nickel ions in films based on poly(acrylic acid)-poly(ethylenimine) complexes are studied via electron microscopy. This approach allows preparation of composites containing nanoparticles that are randomly distributed in the polymer matrix and materials with a regular spatial distribution of nanoparticles across the film thickness and in subsurface layers. The structure of metal-polymer hybrid materials is dependent on the irradiation conditions, the type of reduced metal ions, and their initial content in polymer matrices. The ratio between the rate of nucleation and the rate of growth of nanoparticles in the matrices of interpolyelectrolyte complexes depends on the intensity of ...

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In this study, liquid flame spray (LFS) was used to produce titania, silver and silver-titania deposits of nanoparticles. Titanium(IV)ethoxide (TEOT) and silver nitrate in ethanol solutions were used as precursors and sprayed into turbulent hydrogen-oxygen flame. Production rates of 1.5-40 mg/min of titania were used with silver additions of 1, 2, 4, and 8 wt% compared to titania. Nanoparticle deposits were collected by thermophoretic sampling at six different axial distances from the flame torch head: 3, 5, 10, 12, 15, and 20 cm, of which the all but the last one occurred inside the flame. The deposit samples were analysed by TEM and SAED analysis. The powder samples of the particles were also collected by electric precipitator to XPS and specific surface area analysis. Particle size and effective density after the flame in the aerosol were analysed with SMPS and ELPI. The results from the previous ...

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Short communication. 5 refs., 2 figs.

International Nuclear Information System (INIS)

Short communications only.

Science.gov (United States)

Not Available

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The surface enhanced Raman scattering (SERS) spectra of piperidine in silver colloid solution, on roughened silver electrode and on roughened silver electrode modified with silver nanoparticles were studied, and the high-quality SERS spectra of piperidine on roughened silver electrode modified with silver nanoparticles were obtained for the first time. Surface selection rules derived from the EM enhancement model were employed to deduce piperidine orientations on the different surfaces. On the basis of this, two models of piperidine adsorbed on the surface of the silver nanoparticles were built, and DFT-B3PW91/LanL2dz was applied to calculate the Raman frequencies. It proves that, at higher potential values, the piperidine is perpendicularly standing on the roughened silver electrode surface though its lone-electron ...

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The agglomerate for the element is made from activated charcoal powder, an electrically conducting additive and a neutral electrolyte. The activated charcoal makes up 30 to 50 percent of the weight of the agglomerate. It is a mixture of hydrophobized and unhydrophobized powder in a ratio of 85 to 70 to 15 to 30. The element has high discharge characteristics.

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Synthesis of silver nanoparticles based on a polyol process and variable frequency microwave (VFM) was investigated. Comparing to a thermal method, the reaction by VFM radiation was much faster. The effects of silver nitrate concentration, poly(N-vinylpyrrolidone) (PVP) concentration, reaction time and reaction temperature were studied. It was found that the higher concentration of silver nitrate, longer reaction time and higher temperature increased the particle size while the higher concentration of PVP decreased the particle size.

UK PubMed Central (United Kingdom)

γ-Radiation-induced tumors of Arabidopsis thaliana L. have been produced as a novel approach to isolation of genes that regulate plant development. Tumors excised from irradiated...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Here, a general approach for the preparation of reduced graphite oxide (rGO)-silver nanocomposite has been investigated. Graphite oxide (GO) sheets are used as the nanoscale substrates for the formation of rGO-silver composite. GO sheets and Ag ions can be reduced at the same time, under a mild condition using l-ascorbic acid (l-AA) as reducing agent. This simple approach should find practical applications in the production of rGO-silver nanocomposite. The SEM analysis indicates that the silver particles are dispersed on graphene sheets. Raman signals of rGO in the composite are increased by the attached silver nanoparticles, displaying surface-enhanced Raman scattering activity. The degree of enhancement can be adjusted by varying the quantity of silver nanoparticles in the composite. In ...

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Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. ...

British Library Electronic Table of Contents (United Kingdom)

Arauzo-Carod J.-M. and Viladecans-Marsal E. Industrial location at the intra-metropolitan level: the role of agglomeration economies, Regional Studies. The objective of this paper is to analyse the influence of agglomeration economies on location decisions taken by new firms inside metropolitan areas. As it is assumed that these economies differ according to firms' level of technology, the sample comprises new firms from high-, intermediate- and low-technology industries. Of particularly interest is in analysing the effects of agglomeration economies that are felt over very short distances (inside the metropolitan areas). Introduced in the estimation is the effect of the central city as a determinant for the location of new firms in the rest of the metropolitan area. [image omitted] Arauzo...

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In this study, silver nanoparticles were formed on a natural macroporous matrix, the stem of rice-paper plant, by reducing Ag{sup +} in aqueous solution through in situ processing without using any other stabilizers. The pores of the matrix, with their size of about 100 {mu}m, were thought to act as reaction compartments for the nucleation and growth of silver nanoparticles, and the control of nucleation of silver crystal during the reduction reaction was found to be important to the successful formation of nanosized silver particles onto the matrix. The diameter and amount of resultant silver particles can be controlled by changing the reaction conditions. Under optimized conditions, the content of silver particles in the matrix can reach as high as 1.8 wt% with the particle diameters being kept below 100 nm. The anti-microbial activities in terms of minimum ...

British Library Electronic Table of Contents (United Kingdom)

Bacterial cellulose was produced by Acetobacter xylinum (strain TISTR 975). Bacterial cellulose is an interesting material for using as a wound dressing since it provides moist environment to a wound resulting in a better wound healing. However, bacterial cellulose itself has no antimicrobial activity to prevent wound infection. To achieve antimicrobial activity, silver nanoparticles were impregnated into bacterial cellulose by immersing bacterial cellulose in silver nitrate solution. Sodium borohydride was then used to reduce the absorbed silver ion (Ag+) inside of bacterial cellulose to the metallic silver nanoparticles (Ag0). Silver nanoparticles displayed the optical absorption band around 420nm. The red-shift and broadening of the optical absorption band was observed when the mole rat...

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A 38 year old male dentist developed an oligodendroglioma of the left medial temporal lobe and parasellar region 12 years after radiotherapy with 6600 rads for acromegaly. The 30 cases of radiation-induced gliomas reported in the English literature are reviewed and analysed. The criteria for defining radiation-induced tumours of the central nervous system are proposed as follows: the tumour has a long quiescent ''latency period'', a location in the previously irradiated field, a verified histological difference from a primary condition, and does not arise from a primary condition associated with a genetic syndrome such as neurofibromatosis or tuberous sclerosis. The reported case fulfilled these criteria but appears to be the only reported radiation-induced oligodendroglioma.

UK PubMed Central (United Kingdom)

Silver-haired bat rabies virus (SHBRV) infection induces a strong virus-specific immune response in the periphery of the host, but death is common due to the failure to open the blood-brain barrier...Full Text Available

UK PubMed Central (United Kingdom)

Purpose: This paper reviews and reassesses the internationally accepted niches or ‘targets’ in bone marrow that are sensitive to the induction of leukaemia and primary...Full Text Available

UK PubMed Central (United Kingdom)

PurposeRadiation-induced heart disease (RIHD) is a severe side effect of thoracic radiotherapy. This study examined the effects of PTX and α-tocopherol on...Full Text Available

UK PubMed Central (United Kingdom)

By using EPR measurements of radiation-induced radicals it is possible to utilize human fingernails to estimate radiation dose after-the-fact. One of the potentially limiting factors in this...Full Text Available

International Nuclear Information System (INIS)

... nuclear electric moments nuclear magnetic moments nuclear radii quadrupole

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deodorants and sportswear and silver in washing ma- chines, refrigerators, health care products,

Energy Technology Data Exchange (ETDEWEB)

Monolithic N-channel junction field effect transistors (NJFETs) dc characteristics, small signal parameters and noise have been studied from 300 K down to cryogenic temperatures before and after irradiation with {sup 60}Co {gamma}-rays and fast neutrons (1 MeV). Radiation induced effects on dc parameters and noise are reviewed. Noise spectral density measurements performed at various temperatures have shown that the radiation induces a noise increase which is temperature and frequency dependent. (orig.). 14 refs.

International Nuclear Information System (INIS)

The results of theoretical and experimental investigations, describing the effect of ionizing radiation on wood and its main components and methods for production of wood-plastic composites by means of radiation-induced chemical modification are generalized. Domestic and foreign experience in their production is systematized; physico-mechanical characteristics of new material, simulation and calculation of irradiating devices, as well as calculation and experimental study of #gamma#-radiation attenuation both by wood material and by wood of different species are given. Gamma sources ("6"0Co isotope, a hot loop of a nuclear reactor) as well as electron accelerators are considered as ionizing radiation sources.

Energy Technology Data Exchange (ETDEWEB)

The electronic structure of the clusters (V/sub 3/Si/sub 4/)/sup 12 -/, (Nb/sub 3/Sn/sub 4/)/sup 12 -/(Mo/sub 3/Ge/sub 4/)/sup 15 -/ in crystalline V/sub 3/Si, Nb/sub 3/Sn, Mo/sub 3/Ge compounds is calculated by the Extended Hueckel method. The influence of different types of radiation induced defects on the density of states at the Fermi level (the anti-site defects, the displacement of atoms in linear chains, the vacancy-interstitial type defects) is considered.

International Nuclear Information System (INIS)

The structure of the layers formed on a silver electrode by the adsorption of pyridine, Cl"-, CN"- and SO_4"2"- is discussed. A comparison of the amount of the species adsorbed with their Raman spectra shows that there is no simple relation between the species concentration and the enhancement of the Raman intensity. Furthermore, the inhomogeneity of the layers is shown by Raman microscopy observations. These results lead the authors to propose the formation of a new species stabilized in the colloidal silver layer. The Raman enhancement could be explained by the existence of a resonance effect. (Auth.).

British Library Electronic Table of Contents (United Kingdom)

Wound dressings impregnated with silver have a role to play in aiding to reduce both the dressing and wound microbial bioburden. It is therefore imperative that antimicrobial wound dressings have efficacy on a broad range of clinical significant microorganisms. Accordingly, this study aimed to determine the antimicrobial efficacy of a silver alginate dressing against 115 wound isolates that had been isolated routinely from patients at West Virginia University Hospital. Standardised corrected zones of inhibition (CZOIs) were performed on all clinical isolates. It was found that the silver alginate dressing was able to inhibit the growth of all microorganisms tested. In particular, the silver alginate dressing inhibited the growth of Candida albicans and yeasts with CZOI of 3-115 mm. All met...

Science.gov (United States)

The optical and nonlinear optical properties of colloidal solutions of silver obtained by laser ablation in water and ethanol are studied. It is shown that freshly prepared colloids experience a full or partial sedimentation by changing their nonlinear optical properties. Aqueous colloids undergo a partial sedimentation and their nonlinear optical absorption changes to nonlinear optical transmission. The obtained results are interpreted using the Drude model for metal particles taking the particle size into account and can be explained by the sedimentation of larger silver particles accompanied by the formation of a stable colloid containing silver nanoparticles with a tentatively silver oxide shell. The characteristic size of particles forming such a stable colloid is determined and its optical nonlinearity is estimated.

Energy Technology Data Exchange (ETDEWEB)

When biomass is used as fuel for thermal conversion plants, minerals from the fuel can be responsible for major problems. Generally, these problems are associated with the existence and development of low melting compounds or eutectics, which form sticky layers. In a fluidised bed, this can result in bed-agglomeration and defluidisation. This causes local high temperature, which often accelerates the process. It ultimately can lead to a completely sintered bed content with a glassy phase gluing the bed particles together and shut-down of the plant. The main objective of the title project is to develop a methodology to predict ash/bed agglomeration and sintering problems, to indicate related problems and, furthermore, to identify solution methods to make different types of biomass streams more viable for energy production. Within the present study, selected fuels are subjected to different existing methods together with some new ones, in order ...

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The guiding mechanism is attached by a hinge (swivel) to the supporting frame, and the frame is equipped by hinges (swivels) with hydraulic or pneumatic cylinders mounted on its ends and is attached by hinges (swivels) to the coke ejector and guide respectively. This increases the productivity and efficiency of operating the system.

Energy Technology Data Exchange (ETDEWEB)

The efficiency of NbC on WC grain coarsening in a WC-10wt.%Co hardmetal alloy was demonstrated by hardness measurement and WC granulation observation. The heterogeneous and overall grain growth were controlled. A low temperature experimentally produced NbC was used and compared to the inhibition potential of a commercial NbC powder. The results were the same in terms of structural fineness and hardness. The dispersion of the experimental NbC was not a problem, in spite of its size. The experimental NbC has very large particles, formed by agglomerates of small crystallites. During milling these agglomerates could be broken down. (orig.)

Science.gov (United States)

Macromolecular and polyanionic Na(+)-poly(gamma-glutamic acid) (PGA) silver nitrate complex acted as both a metal ion provider and a particle protector to fabricate nanosized silver colloids under chemical reduction by dextrose. The formation and size of particles have been characterized from transmission electron microscopy (TEM), dynamic light scattering analysis and UV-vis spectrophotometer. The results showed that the average particle size was 17.2+/-3.4 to 37.3+/-5.5 nm, apparently depending on the complex concentration. It was found that the rate constant and conversion of silver nanoparticles were proportional to the concentration of PGA. The growth mechanism of nanosized silver colloid was fully discussed. In addition, the in vitro cytotoxicity evaluated by L929 fibroblasts proliferation and antibacterial activity against Gram-positive strain (methicillin-resistant S. aureus (MRSA)) and ...

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Many assays for oncogenic transformation have been developed ranging from those in established rodent cell lines where morphological alteration is scored, to those in human cells growing in nude mice where tumor invasiveness is scored. In general, systems that are most quantitaive are also the least relevant in terms of human carcinogenesis and human risk estimation. The development of cell culture systems has made it possible to assess at the cellular level the oncogenic potential of a variety of chemical, physical and viral agents. Cell culture systems afford the opportunity to identify factors and conditions that may prevent or enhance cellular transformation by radiation and chemicals. Permissive and protective factors in radiation-induced transformation include thyroid hormone and the tumor promoter TPA that increase the transformation incidence for a given dose of radiation, and retinoids, selenium, vitamin E, and 5-aminobenzamide that inhibit the expression ...

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This study was carried out to evaluate the biochemical and morphological effects of ionizing radiation on ovary. Immature mice (ICR, 3 week-old) were irradiated at a dose of LD{sub 80(30)} at KAERI. The ovaries were collected after 6 hours, 12 hours, 1 day, and 2 days post irradiation. To analyze the morphological changes, histological staining with hematoxylin-eosin, immuno- histochemical preparation using in situ 3'-end labeling was performed. DNA fragmentation analysis and flowcytometric evaluation of DNA extracted from whole ovary were performed. As a result of DNA fragmentation analysis, DNA fragments with 185, 370, and 555 base pairs were clearly shown at 6 hours post irradiation. The percentage of A{sub 0} cell cycle was significantly increased in the irradiated group than control. In situ 3'-end labeled follicles were increased at 6 hours post irradiation. The radiation-induced follicular atresia was taken place via an apoptotic ...

International Nuclear Information System (INIS)

YBa_2Cu_3O_7_-_x thick films have been deposited on silver sheets and MgO single crystals by spray pyrolysis. Film texture is related to film thickness and sintering temperature. The X-ray intensity ratio of the 005 peak to the 110 peak is higher for thin films deposited at the higher temperatures. However, elevated temperatures promote copper diffusion and second-phase formation in films deposited on silver. Films deposited on MgO can have larger grain sizes and are more oriented than those deposited on silver.

Science.gov (United States)

ing materials were ASARCO, 59 purity, copper, silver and gold, while the silicon was Dow-Corning semi- conductor grade (69 purity). ...

International Nuclear Information System (INIS)

Pulse radiolysis was used to examine the nature of the silver species obtained when an aqueous solution containing sequestered Ag"+ ions was reduced by hydrated electrons in the presence of a surfactant macrocyclic crown ether, labeled L, and/or a maltoside surfactant. The initially formed product is the Ag"0(L) species which rapidly loses its ligand (half-life #<=#5 #mu#s) and reacts with another Ag"+(L) ion to form Ag_2"+(L). The latter species decays by a bimolecular process to form the Ag_4"2"+(L)_n species at a faster rate than its ligand free analogue. Ultimately, colloidal metallic silver, (Ag)_n, forms which is stabilized by the surfactant moieties. No long-term stability to the reduced monomolecular species could be obtained.

British Library Electronic Table of Contents (United Kingdom)

The aim of this study was to observe both the clinical signs and symptoms of wounds at risk of infection, that is critically colonised (biofilm infected) and antimicrobial-performance of an ionic silver alginate/carboxymethylcellulose (SACMC) dressing, in comparison with a non silver calcium alginate fibre (AF) dressing, on chronic venous leg and pressure ulcers. Thirty-six patients with venous or pressure ulcers, considered clinically to be critically colonised (biofilm infected), were randomly chosen to receive either an SACMC dressing or a non silver calcium AF dressing. The efficacy of each wound dressing was evaluated over a 4-week period. The primary study endpoints were prevention of infection and progression to wound healing. The SACMC group showed a statistically significant (P = ...

British Library Electronic Table of Contents (United Kingdom)

Abstract: The ability of melatonin as a potent antioxidant was used as a rationale for testing its antiapoptotic ability in normal cells. Recently, melatonin was shown to possess proapoptotic action by increasing reactive oxygen species in certain cancer cells. The modification of radiation-induced apoptosis by melatonin and the expression of apoptosis-associated upstream regulators were studied in normal mice splenocytes and Jurkat T leukemia cells. C57BL/6 mice were exposed to a single whole body X-ray radiation dose of 2 Gy with or without 250 mg/kg melatonin pretreatment. The Jurkat cells were divided into four groups of control, 1 mm melatonin alone, 4 Gy irradiation-only and melatonin pretreatment before irradiation. The highest level of apoptosis in the normal splenic white pulp was...

UK PubMed Central (United Kingdom)

The aim of this study is to determine the effects of silver nanoparticles (Ag-NP) on vascular endothelial growth factor (VEGF)-and interleukin-1 beta (IL-1β)-induced vascular permeability, and...Full Text Available

International Nuclear Information System (INIS)

The effect on an oscillator moving in a medium produced by that part of the radiative force which does not perform work but creates and angular moment is considered. It is shown that the radiative torque turns the dipole toward the axis along which it is moving. Near the axis of motion the dipole executes small oscilltions. The frequency of the oscillations is determined. This effect leads to spontaneous alignment of the dipole moments on moving through the medium. The feasibility of observing the effect experimentally is discussed.

International Nuclear Information System (INIS)

Radiation hardening and radiation-induced chromium (Cr) depletion were related to intergranular stress corrosion cracking (IGSCC) response among various stainless steels (SS). Available data on neutron-irradiated materials were analyzed and correlations developed between fluence, yield strength, grain-boundary Cr concentration, and cracking susceptibility in high-temperature water environments. Large heat-to-heat differences in the critical fluence (0.2 neutrons/cm"2 to 2.5 x 10"2"1 neutrons/cm"2) for IGSCC were documented. Variability often was consistent with yield strength differences among irradiated materials. IGSCC correlated better to yield strength than to fluence for most heats, suggesting a possible role for radiation-induced hardening (and microstructure) on cracking. However, isolated heats revealed a wide range of yield strengths (450 MPa to 800 MPa) necessary to promote IGSCC which could not be explained by strength effects alone. ...

International Nuclear Information System (INIS)

Epidemiological studies will not solve the shape of the dose effect curve for stochastic effects in the low dose range. Unicellular processes are necessary for the primary processes so that no threshold dose exists. This is evident for somatic and genetic mutations. Not clearly solved is this question for the complex carcinogenesis. These processes develop with manifold interacting molecular and cellular steps. (orig.).

International Nuclear Information System (INIS)

Post-irradiation annealing was used to help identify the role of radiation-induced segregation (RIS) in irradiation-assisted stress corrosion cracking (IASCC) by preferentially removing dislocation loop damage from proton-irradiated austenitic stainless steels while leaving the RIS of major and minor alloying elements largely unchanged. The goal of this study is to better understand the underlying mechanisms of IASCC. Simulations of post-irradiation annealing of RIS and dislocation loop microstructure predicted that dislocation loops would be removed preferentially over RIS due to both thermodynamic and kinetic considerations. To verify the simulation predictions, a series of post-irradiation annealing experiments were performed. Both a high purity 304L (HP-304L) and a commercial purity 304 (CP-304) stainless steel alloy were irradiated with 3.2 MeV protons at 360 deg. C to doses of 1.0 and 2.5 dpa. Following irradiation, post-irradiation anneals were performed at ...

UK PubMed Central (United Kingdom)

The three mammalian transforming growth factor (TGF)-β isoforms (TGF-β1, TGF-β2, and TGF-β3) differ in their putative roles in radiation-induced fibrosis in intestine...Full Text Available

CERN Document Server

voltammetric methods. This remained evident for varying extents of silver dissolution. Ag(111) electrodes were oxidised in 0.1 M KCIO sub 4 solutions by a single swept ORC of 0.77x10 sup - sup 3 C cm sup - sup 2. The final rest potential of the Ag(111) working electrode was over the potential range of -36 mV to 114 mV versus the SCE where the silver islands of the reformed surface are believed to be unstable. Results show that a majority of silver islands of all sizes are stable with time, whereas the silver islands with irregular shapes tended to evolve to exhibit higher degrees of spherical geometry. Additionally, the position of the silver islands did not remain constant during the acquisition of STM images. Results from in situ STM demonstrated that the underlying step-terrace morphology of the Ag(111) electrodes did not remain constant with time. Both macroscale and nanoscale ...

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An electrochemical detection method for analyzing sequence-specific DNA using gold nanoparticle DNA probes and subsequent signal amplification step by silver enhancement is described. The assay relies on the electrostatic adsorption of target oligonucleotides onto the sensing surface of the glassy carbon electrode (GCE) and its hybridization to the gold nanoparticle-labeled oligonucleotides DNA probe. After silver deposition onto gold nanoparticles, binding events between probe and target were monitored by the differential pulse voltammetry (DPV) signal of the large number of silver atoms anchored on the hybrids at the electrode surface. The signal intensity difference permits to distinguish between the match of two perfectly matched DNA strands and the near-perfect match where just one base pair was wrong. Coupled with this 'nanoparticle-promoted' reduction of silver signal ...

International Nuclear Information System (INIS)

Functionalizing nanoparticle surfaces is essential for achieving homogeneous dispersions of monodisperse particles in polymer nanocomposites for successful utilization in engineering applications. Functionalization reduces the surface energy of the nanoparticles, thereby limiting the tendency to agglomerate. Moreover, reactive groups on the surface can also participate in the polymerization, creating covalent bonds between the inorganic and organic phases. In this paper, a fluidized bed inductively coupled plasma (FB-ICP) reactor is used to break apart the agglomerates and functionalize commercial TiO2 nanoparticle powders in a batch of several grams. The fluidized bed could be implemented into a continuous flow reactor, potentially making this a viable method to treat larger quantities of commercial powders. The particles are treated with acrylic acid (AA) and tetraethylorthosilicate (TEOS) plasma and the functionalized particles were ...

British Library Electronic Table of Contents (United Kingdom)

Highly dispersed silver nanoparticles embedded in mesoporous thin films (MTFs) have been synthesized by modification of the interior surface of mesoporous silica with ethylenediamine moieties, which provided the coordination sites for the Ag ions, and subsequent reduction under hydrogen atmosphere. TEM observations show the mesoporous parent films have effectively controlled the growth of the synthesized silver nanoparticles. The composite films had an ultrafast nonlinear response time, as fast as 200 fs, and a third-order nonlinear optical susceptibility of 0.94??10?10 esu, which was enhanced by the local field enhancement effect that was present when the silver nanoparticles were embedded in the surrounding dielectric matrix. The origin of the ultrafast nonlinear response and the enhanc...

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A micellar method has been used to prepare silver-coated cobalt (Co-Ag) nanoparticles. The synthesized particles have been deeply characterized by several methods, i.e., XRD, UV-Vis, TEM, XPS, and electrochemical techniques. There is every indication that the obtained particles show a truly core-shell structure. All the nanoparticles obtained under different conditions are in the size range 3-5 nm. High-resolution TEM (HRTEM), Fast Fourier Transformation (FFT), and Selected Area Electron Diffraction (SAED) indicated that the presence of hcp-Co and fcc-Ag, in which cobalt is located in the central area; meanwhile silver is at the edges of the nanoparticle. The absorption band of the Co-Ag colloid shifts to a longer wavelength and broadens relative to that of pure silver colloid. Voltammetric characterization allowed to determine the coverage of the cobalt core.

British Library Electronic Table of Contents (United Kingdom)

In this work, silver-montmorillonite (Ag-MMT) antimicrobial nanoparticles have been obtained by allowing silver ions from nitrate solutions to replace the Na^+ of natural montmorillonite and then to be reduced by a thermal treatment. Ag-MMT were used as active antimicrobial compounds to improve the shelf life of fresh fruit salad. In order to assess their influence on product shelf life, sensorial and microbiological quality has been monitored during the storage. The microbiological quality was determined by monitoring the principal spoilage microorganisms (mesophilic and psychrotrophic bacteria, coliforms, lactic acid bacteria, yeasts and molds). Additionally, the evolution of sensorial quality was assessed by monitoring color, odor, firmness and product overall quality. The Ag-MMT nanopa...

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... (restricted)] 2009, Volume 39, Issue 5 523-529 Parents, peers, or school inputs: Which components of school outcomes are capitalized into house value? by Brasington, David M. & Haurin, Donald R. [Downloadable! (restricted)] 530-541 Trade liberalisation and agglomeration with firm heterogeneity: Forward and backward linkages by Okubo, Toshihiro [Downloadable! (restricted)] 542-552 Alternative measures of homeownership gaps across segregated ...

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Using {gamma}-irradiation-induced reduction in the field of a {sup 60}Co {gamma}-ray source, colloidal silver and gold nanoparticles were prepared from their corresponding metal salts in aqueous solution and compared with those by chemical reduction. The radiation-based method provided silver nanoparticles with higher concentration and narrower size distribution than those obtained by chemical reduction method while there was no significant difference between the two strategies for the preparation of gold nanoparticles. {gamma}-Irradiation of 1.0 x 10{sup -3} M AgNO{sub 3} solution resulted in nearly 100 times more highly concentrated silver colloids than those by citrate reduction. Furthermore, the radiation method could lead to more highly concentrated silver colloids by simply increasing the concentration of AgNO{sub 3} solution up to 2.0 x 10{sup -2} M. The two metal nanoparticles prepared by the ...

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A method to control charge transfer reaction in DNA using hybrid nanometer-sized TiO{sub 2} nanoparticles was developed. In this system extended charge separation reflects the sequence of DNA and was measured using metallic silver deposition or by photocurrent response. Light-induced extended charge separation in these systems was found to be dependent on the DNA-bridge length and sequence. The yield of photocatalytic deposition of silver was studied in systems having GG accepting sites imbedded in AT runs at varying distances from the TiO{sub 2} nanoparticle surface. Weak distance dependence of charge separation indicative of a hole hopping through mediating adenine (A) sites was found. The quantum yield of silver deposition in the system having a GG accepting site placed 8.5 {angstrom} from the nanoparticle surface was found to be {Phi} = 0.70 (70%) and {Phi} = 0.56 (56%) for (A){sub n} and (AT){sub n/2} bridge, ...

Science.gov (United States)

The vibrational states, absorption energies, and diffusions of H in Pd and Pd1-xAgx(0Pd-Ag alloys should avoid the Ag-rich areas.

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Two local repair procedures, one without (9) and the other with (14) a bulbocavernosus muscle graft were performed on 20 patients with a radiation induced rectovaginal fistula. Four patients had two procedures successively. The initial success rate of both procedures was 7/9 and 14/14 respectively. Though the initial result of the bulbocavernosus graft was obviously better, in many of the local repair procedures, subclinical radiation damage progressed, resulting in recurrence of rectovaginal fistula (5), rectovesical fistula (4), pararectal abscess (2) etc. After a mean follow up of around 10 years, the success rate of fistula repair decreased to 5/9 and 13/14 and only 2/9 and 6/14 finally remained without a colostomy. A local repair operation should be restricted to carefully selected cases. The musculus gracilis is proposed as a better vascular graft. If the general condition of the patient does not allow more aggressive reconstructive ...

British Library Electronic Table of Contents (United Kingdom)

Purpose Radiation-induced heart disease (RIHD) is a severe side effect of thoracic radiotherapy. This study examined the effects of pentoxifylline (PTX) and a-tocopherol on cardiac injury in a rat model of RIHD. Methods and Materials Male Sprague-Dawley rats received fractionated local heart irradiation with a daily dose of 9 Gy for 5 days and were observed for 6 months after irradiation. Rats were treated with a combination of PTX, 100 mg/kg/day, and a-tocopherol (20 IU/kg/day) and received these compounds either from 1 week before until 6 months after irradiation or starting 3 months after irradiation, a time point at which histopathologic changes become apparent in our model of RIHD. Results Radiation-induced increases in left ventricular diastolic pressure (in mm Hg: 35 +- 6 after sham...

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We have been investigating radiation-induced neoplastic transformants of C3H 10T1/2 mouse fibroblasts for evidence of heritable changes. C3H 10T1/2 cells were treated with 8 Gy X rays. After approximately 8 weeks of culture, type II/III foci were isolated from the monolayer using cloning rings. Cell lines developed from these foci, and clones established from these cell lines, were examined for DNA content. The isolated focus-derived populations and derived clones often display aneuploidy and/or polyploidization. In one instance a clone (derived from a single cell) displayed multiple polyploidies. During passage the ploidy of many of the anomalous populations gradually reverted to the ploidy of the non-neoplastically transformed state. The morphological features associated with the neoplastic transformation event were nevertheless retained. The results demonstrate that exposure to radiation can induce, in association with morphological neoplastic transformation, a ...

Science.gov (United States)

Ionizing radiation is a standard treatment for various human solid tumors. However, several clinical studies showed that a significant proportion of patients undergoing radiotherapy for hepatocellular carcinoma (HCC) develop intrahepatic and extrahepatic metastasis. Understanding of radiation-induced cancer cell invasiveness and behavior is essential and of great important for developing suitable treatment strategies to contain cancer spread. Therefore, in this study we evaluated the effectiveness of using swept source optical coherence tomography (SS-OCT) to monitor the enhancement of HCC cell invasiveness by radiation. SS-OCT images were acquired and recorded to obtain three-dimensional data sets per four hours in 48 hours after irradiating HepG2 cells with 7.5 Gy. The cell migration behavior in three-dimensional tissue models was quantified from images of radiation-induced and sham-irradiated cells.

Energy Technology Data Exchange (ETDEWEB)

We demonstrate the rapid optical characterization of large numbers of individual metal nanoparticles freely diffusing in colloidal solution by confocal laser spectroscopy. We find that hollow gold nanospheres and solid silver nanoparticles linked with a bifunctional ligand, both designed nanostructures, exhibit significantly higher monodispersity in their Rayleigh and Raman scattering response than randomly aggregated gold and silver nanoparticles. We show that measurements of rotational diffusion timescales allow sizing of particles significantly more reliably than can be obtained using translational diffusion timescales.

Science.gov (United States)

The possibility of using lead and lead-bismuth mixed oxides as positive active materials in organic electrolyte lithium cells with a working voltage similar to those of silver zinc cells has been considered. Button cells of SR 44 size have been developed as a test vehicle and studied under various conditions of discharge rate and storage. This paper describes the performance characteristics obtained under these conditions and suggests in conclusion the possible replacement of silver zinc cells by such systems for a large range of low-rate applications on the basis of cost effectiveness.

Science.gov (United States)

In this contract, Laser-assisted processing techniques for producing high-quality solar cell metallization patterns are being investigated, developed, and characterized. The tasks comprising these investigations are outlined. Four new batches of solar cells were processed, in addition to several test runs on wafers, using the laser decomposition of spun-on silver neodecanoate to metallize cells. Decomposition of silver neodecanoate was carried out at different laser powers on different cells on a given wafer to determine whether this would have any effect on cell performance. A one watt laser power gave an electroplated linewidth of 50 microns , while at 8 watts the line width was 90 microns.

International Nuclear Information System (INIS)

By the linear augmented plane wave method (APW) the energy zone of silver and technetium structure is calculated. The potential has been determined by means of superposition of atomic charge densities according to slater exchange method. Total and partial state densities have been calculated by the tetrahedron method. The APW-method convergence on the example of silver is studied, the comparison with the calculation results by the APW method and other data is carried out. The APW method high efficiency is pointed out. In dipole approximation the intensity distribution in L"3, M"5 N"3 technetium emission spectra is calculated.

International Nuclear Information System (INIS)

This is a preliminary study on the sound absorption properties of two tropical hardwoods, Light Red Meranti and Ramin, and their wood-polymer composites. Sound absorption is measured using a standing wave apparatus. The samples are of one thickness (7 mm) and cut longitudinally. Wood-polymer composites are made by impregnating the samples with methyl methacrylate which is polymerized in situ through #gamma#-irradiation. Both woods and their composites are better sound absorbers at higher sound frequencies. With partial impregnation, the absorption coefficients are improved upon particularly in the region between 1-3 kHz. (author).

International Nuclear Information System (INIS)

Polymerizing effects of high energy radiation has been found suitable for preparation of wood-polymer composites. In the present work after evaluating polymer products that have been obtained by irradiation method, wood-polymer composites have been prepared by in situ polymerization of vinyl acetate, acrylic acid and acrylic acid/styrene mixture using two samples of Iranian hardwoods, Beech and Hornbeam. These woods and their composites have been tested for their physical and mechanical properties. The results have shown that chemical bonding between polymer and the cell wall component lead to better strength properties in the composites. (author).

International Nuclear Information System (INIS)

A wood/polymer composite was produced by impregnating Ramin wood with methyl methacrylate monomer and subsequently polymerizing it by gamma irradiation. To assess the improvement in compression strength of the wood caused by the polymer impregnation, a microbuckling compression failure mechanism was used to model the compression failure of the composite. Such a mechanism was found to predict a linear relationship between the compression strength and the percentage polymer impregnation (by weight). Uniaxial compression test results at 45(#+-#5)% and 90(#+-#5)% relative humidity levels, after being statistically analysed, showed that such a linear relationship was valid for up to 100% polymer impregnation. (author).

International Nuclear Information System (INIS)

Wood-plastic composites (WPC) have been prepared with five low-grade woods, native to Syria, using three monomer systems; acrylamide, butylmethacrylate, and styrene, with methanol as the swelling solvent. Polymerization was induced at various radiation doses (10, 20, and 30 kGy) at a dose rate of 3.5 kGy/h using a "6"0Co gamma radiation source. Some physical properties of WPC, namely polymer loading and compression strength have been measured. The polymer loading decreases approximately with increasing density of the wood species used.

International Nuclear Information System (INIS)

Spectra of e.p.r. radicals in cellulose and timber gamma-irradiated at 77 and 300 K have been measured. Radiation yields and the kinetics of radicals accumulation have been studied. The effect of ionizing radiation on cellulose is the appearance of radicals resulting from rupture of C-H bonds in positions 1 and 4. Timber, additionally, forms ''lignin'' radicals. A mechanism of cellulose and timber radiolysis is suggested. ''Lignin''-type compounds present in timber protect polysaccharides from radiation-induced destruction.

Energy Technology Data Exchange (ETDEWEB)

A mesoscopically ordered lamellar gel phase of a polymer-grafted, lipid-based complex fluid is used as a scaffolding to spatially organize inorganic nanoparticles. The complex fluid provides both a highly anisotropic environment and a segregated aqueous and organic domains in which inorganic nanoparticles can be selectively placed by tailoring their size and surface characteristics. Three types of silver nanoparticles -- underivatized, surfactant-stabilized, and dodecanthiol-derivatized -- were evaluated. Comparison of the surface plasmon resonance of the various silver particles dispersed in conventional solvents to those contained within the complex fluid was used to determine the region of spatial localization in the lamellar gel phase. Silver particles rendered hydrophobic by capping with an alkane thiol insert into the hydrocarbon bilayer region. Surfactant-stabilized and underivatized silver ...

Energy Technology Data Exchange (ETDEWEB)

This short survey focuses on the main radiation-induced base lesions that have been identified within cellular DNA. For this purpose, sensitive assays that are aimed at measuring a few modifications per 10{sup 7} normal bases were set-up. In that respect high performance liquid chromatography - tandem mass spectrometry (CLHP-MS/MS) was found to be able to single out the formation of 9 oxidized nucleosides and two modified nucleo-bases out of the 70 oxidative base lesions that have been identified in model systems. As a striking result, it was found that in the DNA of {gamma}-irradiated human monocytes, the formamide-pyrimidine derivative of guanine is produced in a higher yield than the ubiquitous 8-oxo-7,8-dihydro-guanine damage, both arising from the same radical precursor. However, relatively high doses of ionizing radiation (> 20 Gy) have to be applied in order to detect an increase in the level of the damage. This is due to the low efficiency for both ...

International Nuclear Information System (INIS)

The process of mouse skin tumor formation is subdivided into three operational stages. These stages include initiation, promotion and progression. Ionizing radiation has been found to be a weak initiating agent in the production of malignant squamous cell carcinomas, a complete carcinogen and an agent effective in causing tumor progression. Four skin tumor histologies have been seen with ionizing radiation: benign papillomas, squamous (SCC) and basal (BCC) cell carcinomas and fibrosarcomas. Distinct non-ras transforming genes have been detected in radiation initiated SCCs. A benign papilloma cell line (308) was used as a model system to study ionizing radiation induced progression. A variant 308 cell line (308 10 Gy 5) derived by irradiation of the parental 308 cell has been characterized. The 308 10 Gy 5 cells unlike the parental 308 cells from malignant tumors in athymic nude mice upon subcutaneous injection. The variant 308 10 Gy 5 cells ...

International Nuclear Information System (INIS)

Full text: DNA rearrangement events leading to chromosomal aberrations are central to ionizing radiation-induced cell death. Although DNA double-strand breaks are probably the lesion that initiates formation of chromosomal aberrations, little is understood about the molecular mechanisms that generate and modulate DNA rearrangement. Examination of the sequences that flank sites of DNA rearrangement may provide information regarding the processes and enzymes involved in rearrangement events. Accordingly, we developed a method using inverse PCR that allows the detection and sequencing of putative radiation-induced DNA rearrangements in defined regions of the human genome. The method can detect single copies of a rearrangement event that has occurred in a particular region of the genome and, therefore, DNA rearrangement detection does not require survival and continued multiplication of the affected cell. Ionizing ...

Science.gov (United States)

In 1977 and 1978, workers at Idaho National Engineering Laboratory (INEL) developed and tested a process for the regeneration and reuse of silver mordenite, AgZ, used to trap iodine from the dissolver off-gas stream of a nuclear fuel reprocessing plant. We were requested by the Airborne Waste Management Program Office of the Department of Energy to perform a confirmatory recycle study using repeated loadings at about 150/sup 0/C with elemental iodine, each followed by a drying step at 300/sup 0/C, then by iodine removal using elemental hydrogen at 500/sup 0/C. The results of our study show that AgZ can be recycled. There was considerable difficulty in stripping the iodine at 500/sup 0/C.; however, this step went reasonably well at 550/sup 0/C or slightly higher, with no apparent loss in the iodine-loading capacity of the AgZ. Large releases of elemental iodine occurred during the drying stage and the early part of the stripping stage. Lead zeolite, which was ...

Energy Technology Data Exchange (ETDEWEB)

Ion implantation of Si (60 keV, 1{times}10{sup 14}/cm{sup 2}) has been used to introduce excess interstitials into silicon predoped with high background concentrations of B, which were varied between 1{times}10{sup 18} and 1{times}10{sup 19}/cm{sup 3}. Following post-implantation annealing at 740{degree}C for 15 min to allow agglomeration of the available interstitials into elongated {l_brace}311{r_brace} defects, the density of the agglomerated interstitials was determined by plan-view transmission electron microscopy observation of the defects. We report a significant reduction in the fraction of excess interstitials trapped in {l_brace}311{r_brace} defects as a function of boron concentration, up to nearly complete disappearance of the {l_brace}311{r_brace} defects at boron concentrations of 1{times}10{sup 19}/cm{sup 3}. The reduction of the excess interstitial concentration is interpreted in terms of boron-interstitial clustering, and ...

Energy Technology Data Exchange (ETDEWEB)

The goal of this project is to develop a bench-scale procedure to produce clean, desulfurized, premium-quality chars from the Illinois basin coals. This goal is achieved by utilizing the effective capabilty of smectites in combination with methane to manipulate the char yields. The major objectives are: to determine the optimum water- ground particle size for the maximum reduction of pyrite and minerals by the selective-bitumen agglomeration process; to evaluate the type of smectite and its interlamellar cation which enhances the premium-quality char yields; to find the mode of dispersion of smectites in clean coal which retards the agglomeration of char during mild gasification; to probe the conditions that maximize the desulfurized clean-char yields under a combination of methane+oxygen or helium+oxygen; to characterize and accomplish a material balance of chars, liquids, and gases produced during mild gasification; to identify the conditions ...

DEFF Research Database (Denmark)

In fluid bed processing in the chemical, food or pharmaceutical industries, pneumatic nozzles are typically used to convert binder or coating liquids into droplets. Producing fine droplets from liquids in a gas phase is termed atomisation, and it involves complex phenomena which are not yet fully understood. This paper provides a systematic and up-to-date review of two-fluid nozzle designs and principles together with a presentation of nozzle fundamentals introducing basic nozzle theory and thermodynamics. Correlations for the prediction of mean droplet diameters are reviewed, compared and accompanied by a discussion of their use.

International Nuclear Information System (INIS)

A nanoparticle generator based on the principle of electrical discharge (PALAS GFG-1000) was used to produce nanoparticles of different chemical natures. The fractions of electrically neutral particles were then measured by means of a Spectrometre de Mobilite Electrique Circulaire (SMEC, i.e. radial-flow mobility analyzer) for different operating conditions. The experimental results were compared with the theoretical values calculated from the Fuchs extended charge equilibrium model for spherical particles and agglomerates. For the smallest particles (below 20 nm), the deviations observed remain below 10%, and tend towards 20% for larger particles (over 35 nm).

Energy Technology Data Exchange (ETDEWEB)

Gold and silver nanoparticles display extraordinarily large apparent refractive indices near their plasmon resonance (PR) wavelengths. These nanoparticles show good contrast in a narrow spectral band but are poorly resolved at other wavelengths in differential interference contrast (DIC) microscopy. The wavelength dependence of DIC contrast of gold/silver nanoparticles is interpreted in terms of Mie's theory and DIC working principles. We further exploit this wavelength dependence by modifying a DIC microscope to enable simultaneous imaging at two wavelengths. We demonstrate that gold/silver nanoparticles immobilized on the same glass slides through hybridization can be differentiated and imaged separately. High-contrast, video-rate images of living cells can be recorded both with and without illuminating the gold nanoparticle probes, providing definitive probe identification. Dual-wavelength DIC microscopy thus ...

Energy Technology Data Exchange (ETDEWEB)

A composite film consisting of the mixed-addenda Keggin-type polyoxometalate alpha-K{sub 3}PMo{sub 3}W{sub 9}O{sub 40} (PMo{sub 3}W{sub 9}) and silver nanoparticles (AgNPs) was fabricated on quartz, silicon, and ITO by the layer-by-layer self-assembly method. The regular growth of the multilayer film was monitored by UV-vis spectroscopy, and the morphology was measured by atomic force microscopy (AFM). The multilayer film embedded by AgNPs exhibited the photo-luminescence ascribed to electronic transitions from excited states to d levels of the silver nanoparticles. The composite film also showed electrocatalytic activity towards reduction of NO{sub 2}{sup -}, H{sub 2}O{sub 2}, ClO{sub 3}{sup -}, BrO{sub 3}{sup -}, and IO{sub 3}{sup -} attributed to tungsten-centered and molybdenum-centered redox processes of PMo{sub 3}W{sub 9}.

Energy Technology Data Exchange (ETDEWEB)

The shifts induced by equimolar mixture of typical lanthanide shift reagent such as 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octadionato europium with silver trifluoroacetate in /sup 1/H NMR spectra of aromatic hydrocarbons have been used for analytical purposes; the NMR determination of m- and p-xylenes in mixtures has been chosen as an example. The use has been made of the difference between induced shifts of methyl group signals in the /sup 1/H NMR spectra of m- and p-xylenes. The magnitude of induced shifts of methyl groups signal in m-xylene is always larger than that of p-isomer, irrespective of contents of m- and p-xylenes in mixture.

Energy Technology Data Exchange (ETDEWEB)

In pre-experiments a tubular reactor was checked whether it is suitable for kinetic measurement on the system of the silver-catalysed partial oxidation of methanol to formaldehyde. Detrimental effects of heat-transfer and mass-transfer on the experimental results were ruled out. Investigations on the characteristics of the reaction showed that it is possible to manipulate the composition of the product mixture by changing the inlet concentration of the reactants. A modified power-law model was established to describe the reaction kinetics. It considers the preadsorption step of oxygen on the catalysts surface and fits the experimental data quite well. During the rapid oxidation the catalysts surface undergoes a drastic change. It gets coarse and has an adsorption capacity of 11 m{sup 2}/g after being exposed to the reaction mixture. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Nanoparticles of silver halides have been prepared by mixing silver halide powder with a single liquid phase consisting of an ionic liquid, isooctane, n-decanol and water. Much higher nanoparticle concentrations may be formed with ionic liquids using this new simple method than are found with conventionally applied surfactants. This method also emphasizes the applicability of ionic liquids as versatile components in microemulsions and as solvents for the synthesis of nanomaterials. The effect on the nanoparticles of changing the composition of the liquid mixtures and the nature of the ionic liquid is analysed. High nanoparticle concentrations were only found with chloride based ionic liquids, indicating the importance of the ionic liquid anion in the mechanism of the reaction.

Science.gov (United States)

A fine-grained photosensitive layer was prepared for electron- microscopic radioautography. The layer was obtained by evaporating Ag at low pressure and temperature on electron microscope grids and sensitizing the silvered grids with Br/sub 2/. The resulting particles had an average diameter of -- 100 A. The sensitivity of the layer to ionizing radiation was tested by sprinkling the grids with fine uranium aeetate particles and examining the processed grids in an electron microscope. Shont tracks and side spurs were observed which are probably due to alpha radiation from U/sup 235/ and secondary electrons scattered from the silver, respectively. Tests with P/sup 32/- phosphate are also described. (D.L.C.)

British Library Electronic Table of Contents (United Kingdom)

Yb3+?Tm3+ codoped tellurite glasses containing silver nanoparticles (NPs) were synthesized and characterized using transmission electron microscopy and optical techniques. The samples? composition and the nucleation of NPs were investigated using electron diffraction and energy dispersive spectroscopy. For the optical experiments, the samples were excited using a diode laser operating at 980?nm, in resonance with the Yb3+ transition 2F7/2?2F5/2. Photoluminescence (PL) bands corresponding to Tm3+ transitions were observed at 480, 650, and 800?nm due to the Yb3+? Tm3+ energy transfer. PL enhancement was achieved by heat-treatment of the samples at 325?C during different time intervals. The growth of the PL bands correlates with the increase of the silver NPs concentration. The relevant mecha...

Energy Technology Data Exchange (ETDEWEB)

In the dehydrodesulfurization of ethanethiol at 400/sup 0/C, the activities of sodium X, Y, and A zeolites decreased in the order given as did the activities of nickel, cobalt, zinc, cadmium, copper, silver, lead, manganese, barium, calcium, sodium, and iron Y zeolite catalysts. A volcano-shape order was observed between the catalytic activity and the electronegativity of the metal ions. The changes in the activity of hydrogen Y zeolite catalyst in ethanethiol dehydrodesulfurization and cumene dealkylation by calcination agreed with the decrease in the Broensted acidity but were independent of Lewis acidity. For hydrodesulfurization of thiophene, the activities of nickel, cobalt, copper, and silver Y zeolite catalysts decreased in the order given and were greater than for a commercial hydrodesulfurization catalyst; reduced and presulfided catalysts showed selective hydrodesulfurization activity. Addition of 5% of nickel or molybdenum oxides to ...

Energy Technology Data Exchange (ETDEWEB)

The authors have studied the distribution of H-3 labelled schistosomicidal drug in mice by autoradiography. The H-3-labelled substances were found in liver and kidney and in successfully decreasing amounts in brain, lung, heart, fat, testis, pancreas and spleen. In various cells the silver granules were present mainly in the cytoplasms but a few in the nucleus. After administration of this labelled schistosomicidal drug, the mice were killed and studied in groups successively at 4, 8, 24 hrs. No difference in the distribution of silver granules were observed. This fact indicated that, this drug was rapidly absorbed and highly concentrated with a long duration of reservation in liver. All of these favours the schistosomicidal effect of the drug. As this drug was highly concentrated in the cytoplasm of liver cells, that might provide a pathophysiologic basis for the explanation of jaundice in the clinical practice. Moreover, the appearance of ...

Energy Technology Data Exchange (ETDEWEB)

Most plans for the disposition of surplus nuclear materials involve storage in sealed containers where the evolution of gases from reactions of adsorbed water could present both pressure and flammability hazards[l] . Despite efforts such as calcining the material to minimize the water content prior to packaging, both residual moisture and readsorbed water may be present in the final containers . Given the anticipated temperature excursions during transportation and storage, this water may thermally desorb, increasing the pressure, and/or thermally dissociate to produce H2 gas, increasing flammability hazards . In addition, the radiation from the nuclear material may induce radiolysis of the water with the likely products being water vapor, H2, 02 and H2O2. In order to better understand the relative importance of the thermal- and radiationinduced chemistry, we have studied the interactions of water on single crystals of uranium dioxide .

Energy Technology Data Exchange (ETDEWEB)

Elevation of zinc protoporphyrin (ZPP) levels in the blood has served as an indicator of lead poisoning and iron deficiency anemia for many years. We have discovered that sublethal doses of whole body irradiation with x-rays also elevates ZPP 2-3-fold over normal levels. The ZPP level does not begin to increase until days 12-14 postirradiation and peaks between days 18 and 20 before returning to normal levels between days 28 and 35. Increasing the radiation dose delays the onset of the rise in ZPP, but does not affect the magnitude of the elevation. At lethal doses, ZPP elevation is not observed. Neither of the two previously described mechanisms that cause elevations of ZPP, namely iron deficiency and inhibition of ferrochelatase, are responsible for the radiation-induced elevation of ZPP. The elevation of ZPP appears to be correlated with the recovery of the hematopoietic system from radiation injury.

International Nuclear Information System (INIS)

The synthetic process of polyethylene cation exchange capillary via radiation grafting polystyrene by simultaneous irradiation with "6"0Co #gamma#-ray source and sulfonation with concentrated H_2SO_4 was studied. The effects of dose, dose rate, monomer concentration, solvents, temperature and crosslinking agents on the graft copolymerization of styrene with polyethylene capillary were illustrated. The relationship between the radiation grafting conditions and the properties of ion-exchange capillary were examined. A polyethylene cation exchange capillary with I.D. 0.8 mm, length 20 m, exchange capacity 0.7 Meq/g 60% capacity in 10 s (flow rate 20 ml/min) was prepared. No significant loss of copacity was found from this ion-exchange capillary after 200 adsorption/regeneration cycles.

International Nuclear Information System (INIS)

We study CP-violating phenomena in the production, mixing and decay of a coupled system of CP-violating neutral Higgs bosons at #gamma##gamma# colliders, assuming a Minimal Supersymmetric Standard Model (MSSM) Higgs sector in which CP violation is radiatively induced by phases in the soft supersymmetry-breaking gaugino masses and third-generation trilinear squark couplings. We discuss CP asymmetries in the production and decays of #mu#"+#mu#"-, #tau#"+#tau#"-, b-bar b and t-bar t pairs. We find large asymmetries when two (or all three) neutral Higgs bosons are nearly degenerate with mass differences comparable to their decay widths, as happens naturally in the CP-violating MSSM for values of tan#beta#-bar 5 (30) and large (small) charged Higgs-boson masses.

Energy Technology Data Exchange (ETDEWEB)

Two patients who developed large intracranial vessel occlusion after standard radiation therapy for brain tumor are described. This form of vascular occlusion is usually seen in patients who have previously been treated by radiotherapy for intracranial tumor who then develop a relatively acute change in neurologic status. Histology of the lesion mimics accelerated focal arteriosclerosis. The clinical and radiographic manifestations of one case were highly atypical. The vasculopathy became evident shortly after termination of radiation therapy for a fourth ventricular ependymoma, and the angiographic picture stimulated a diffuse arteritis. The second patient was more typical, with clinical symptoms developing 12 years after radiation therapy for an oligodendroglioma. Occlusion of a proximal vessel that had been included in the radiation port was demonstrated radiographically and confirmed by pathologic examination. The clinical, angiographic, and histologic features of these two cases ...

Energy Technology Data Exchange (ETDEWEB)

Photoluminescence spectroscopy measurements were carried out for silicon 50{mu}m BSFR space solar cells irradiated with 1MeV electrons with a fluence exceeding 1 x 10{sup 16} e/cm{sup 2} and 10MeV protons with a fluence exceeding 1 x 10{sup 13} p/cm{sup 2}. The results were compared with the previous result performed in a relative low fluence region, and the radiation-induced defects which cause anomalous degradation of the cell performance in such large fluence regions were discussed. As far as we know, this is the first report which presents the PL measurement results at 4.2K of the large fluence radiation irradiated silicon solar cells. (author)

International Nuclear Information System (INIS)

Nickel ion radiation at 500 C was shown to have a strong effect on the surface electrochemistry and intergranular corrosion (IGC) of stainless steel (SS). Measured current densities in a 1 N sulfuric acid solution at room temperature were increased at active-passive, passive, and transpassive potentials. Radiation effects on the current decay behavior and susecptibility to IGC were similar for a fine-grained (FG) S alloy and for a very large-grained (LG) SS. Radiation-induced segregation (RIS) at the surface was believed to promote higher currents at short times, whereas segregation at grain boundaries was responsible for IG attack. Analytical electron microscopy (AEM) measurements revealed chromium and iron depletion plus Ni and silicon enrichment at grain boundaries in irradiated specimens. Si enhanced dissolution at transpassive potentials, whereas Cr depletion did the same at active-passive and passive potentials.

International Nuclear Information System (INIS)

Increased levels of epidermal growth factor receptor have been reported in a variety of tumors, including pulmonary squamous cell carcinomas in man. The purpose of this study was to determine if increased levels of epidermal growth factor (EGFR) were present in lung tumors from Beagle dogs that had been exposed to "2"3"9PuO_2- Using immunohistochemical techniques, sections from 17 lung tumors were examined for the presence of EGFR. Seven of the tumors were strongly positive for EGFR; the remainder of the tumors and the normal lung sections were negative. The positive immunostaining could not be correlated with the histologic phenotype of the tumors. Work is in progress to determine the level of EGFR in preneoplastic, proliferative epithelial foci in the Iung. (author)

International Nuclear Information System (INIS)

The effect of exposure to gamma rays on LPO contents in liver, spleen and kidney of mice and the anti-lipid-peroxidation of preparations of chinonin, tannic acid and squalene were reported. All these preparations were given by intragastric perfusion. For LPO, a modified method of TBA spectrophotometry was used for determination. The results show that LPO contents in tissues increased 72 h after whole-body exposure of mice to gamma rays, that in range of 0-4 Gy, there was a linear relationship between radiation doses and LPO contents, and that all three preparations were effective in reduction of the LPO content in liver, spleen and kidney of mice, with chinonin (at dose of 0.35 mg/mouse#centre dot#day) being more effective than tannic acid (at dose of 15 mg/mouse#centre dot#day) and squalene (at dose of 0.6 mg/mouse#centre dot#day).

Energy Technology Data Exchange (ETDEWEB)

Data are presented to support the hypothesis that the initial step in the morphologic transformation of irradiated rodent (BALB/3T3) cells is a frequent cellular event involving a large fraction of the irradiated population. This process appears to involve DNA damage, but not to represent a targeted mutation in specific structural gene(s). Morphologic transformation and immortalization appear to be distinct steps in the overall process of transformation. In contradistinction to rodent cells, immortalization is a very rare event in human diploid cells which is induced at extremely low frequencies. The hypothesis is presented that immortality develops among clones of cells bearing stable chromosomal rearrangements which emerge during the proliferation of a population of radiation damaged cells.

Energy Technology Data Exchange (ETDEWEB)

The content and biosynthesis of glycosaminoglycans (GAGs) were studied in pig thigh muscle after acute local {gamma}-irradiation. Seven months following irradiation, the muscular tissue next to the irradiation cone was replaced by severe mutilating fibrosis delimited by an intermediary perifibrotic zone. Results showed a parallel increase of collagen and GAG content in perifibrotic and fibrotic tissues. Sulphated GAGs, heparan sulphate and dermatan sulphate were preferentially accumulated in fibrotic tissue, while the hyaluronic acid content increased only slightly. Synthesis of sulphated GAGs was more elevated in fibrotic tissue than in perifibrotic zone as compared with normal muscle. Seven months after irradiation well-developed fibrotic tissue continued to synthesize and to accumulate extracellular matrix macromolecules. (Author).

International Nuclear Information System (INIS)

The project is intended to yield information on the transfer factors describing the transfer of ingested radionuclides to breast milk for the following elements: antimony, cerium, chromium, cobalt, gallium, lanthanum, molybdenum, niobium, radium, ruthenium, silver, thorium, titanium, and uranium. Those yet unknown or poorly known transfer factors are required in order to be able to develop a reliable model for description and assessment of the transfer of the radionuclides and the possibly resulting hazardous doses to infants, and for subsequent formulation of recommendations for radiological protection of the population. (orig./CB)

Energy Technology Data Exchange (ETDEWEB)

In this study, nanoparticle penetration was measured with a wide range of filter media using silver nanoparticles from 3 nm to 20 nm at three different face velocities in order to define nanoparticle filtration characteristics of commercial fibrous filter media. The silver particles were generated by heating a pure silver powder source via an electric furnace with a temperature of 870 deg. C, which was found to be the optimal temperature for generating an adequate amount of silver nanoparticles for the size range specified above. After size classification using a nano-DMA, the particle counts were measured by an Ultrafine Condensation Particle Counter (UCPC) both upstream and downstream of the test filter to determine the nanoparticle penetration for each specific particle size. Particle sampling time continued long enough to detect more than 10{sup 5} counts at the upstream and 10 counts at the ...

Wastenet

... - Climate Action Programme cloud computing, climaet change, carbon emissions, verdantix, cloud, it, computer cloud computing, climaet change, carbon emissions,...verdantix, cloud, it, computer GreenMedia.com AidForumOnline.org ClimateActionProgramme.org Search Climate Action... In partnership with the United Nations ...

International Nuclear Information System (INIS)

On 21 October 1994, three brothers entered a waste repository at Tammiku, Estonia, without authorization and removed a metal container enclosing a caesium-137 source. During the removal the source was dislodged and fell to the ground. One of the men picked up the source, placed it in his pocket and took it to his home in the nearby village of Kiisa. Very soon after entry into the repository he began to feel ill, and few hours later he began to vomit. The man was subsequently admitted to hospital with severe injuries to his leg and hip and died on 2 November 1994. The injury and subsequent death were not attributed to radiation exposure, and the source remained in the man's house with his wife and stepson and the boy's great-grandmother. The boy was hospitalized on 17 November with severe burns on his hands, and these were identified by a doctor as radiation induced. The authorities were alerted, and the Estonian Rescue Board recovered the ...

Science.gov (United States)

Endothelial dysfunction and increased platelet aggregation may be involved in the pathogenesis of normal tissue radiation toxicity. This study assessed clopidogrel, an inhibitor of ADP-induced platelet aggregation, as a modulator of intestinal radiation injury (radiation enteropathy). Rat small intestine was exposed to 21 Gy X-radiation. Clopidogrel (20 mg/kg/day) or vehicle was administered from 2 days before to 10 days after irradiation. Structural radiation injury, neutrophil infiltration, smooth muscle cell proliferation, collagen content, and TGF-beta1 expression were assessed 2 weeks (early phase) and 26 weeks (delayed phase) after irradiation, using quantitative histology and immunohistochemistry, morphometry, and real-time fluorogenic probe RT-PCR. Irradiated intestine exhibited significant histopathologic injury, reduced mucosal surface area, vascular sclerosis, intestinal wall fibrosis, increased collagen content, and increased TGF-beta1 expression. Clopidogrel reduced ...

International Nuclear Information System (INIS)

7,959 patients were examined by radionuclide in-vivo methods within one year, 1,228 of them by application of "1"3"1I-iodide (radioiodine test and scintigraphy of the thyroid gland). In compliance with the ICRP publications 26 and 27 the somatically effective equivalent dose H/sub s,eff/ was ascertained for several examining methods, derived from it the collective dose S/sub s,eff/ and considering a part of manifestation resulting from the age distribution of patients, the somatic risk regarding radiation-induced malignoma with fatal termination. For the patients examined by "1"3"1I-iodide the collective dose was 79.9 man x Sv and the mean somatic risk 30 x 10"-"5 with a part of manifestation of 0.39 accordig to 0.37 radiation-induced malignomas with fatal termination. For all patients examined by other radiopharmaceuticals the collective dose was 14.07 man x Sv, the mean somatic risk 1.7 x 10"-"5 according to 0.11 malignomas. The average ...

Energy Technology Data Exchange (ETDEWEB)

Wastes and dusts from steel industry, non-ferrous metallurgy and other branches can be utilised e.g. in agglomeration processes (sintering, pelletising or briquetting) and by injection into shaft furnaces. This paper deals with the second way. Combustion and reduction behaviour of iron- and carbon-rich metallurgical dusts and sludges containing lead, zinc and alkali as well as other wastes with and without pulverised coal (PC) has been studied when injecting into shaft furnaces. Following shaft furnaces have been examined: blast furnace, cupola furnace, OxiCup furnace and imperial-smelting furnace. Investigations have been done at laboratory and industrial scale. Some dusts and wastes under certain conditions can be not only reused but can also improve combustion efficiency at the tuyeres as well as furnace performance and productivity.

British Library Electronic Table of Contents (United Kingdom)

This paper presents a detailed characterization and rheometric property study of in-situ sodium activated, organomodified bentonite clay - styrene-butadiene rubber (SBR) nanocomposite. It was found that around 10phr loading was the optimum level for maximum effect of the organo clay. The WAXD data indicated that at higher loading there was formation of agglomerations in the matrix. It was found that organo clay compound exhibited lower maximum torque in comparison to equivalent amount of carbon black loaded compound. The nanocomposites were also used for partial replacement of N330 carbon black in a highly black loaded compound. Part replacement of the carbon black with nano-clay reduced the maximum rheometric torque in comparison to the control compound. Detail study revealed that with sl...

British Library Electronic Table of Contents (United Kingdom)

This study correlates the post start cell performance and impedance with the cold start process in the subzero environment. The sequential failed cold starts are deliberately conducted as well as the start at small current density. Here the failed cold start means the cell voltage drops to or below zero within very short time during the start process. It is found that there are reversible performance losses for the sequential failed cold starts, while not obvious degradation and no recovery happen for the start at small current density. Using the thin film and agglomerate model, it is confirmed that this is due to the water blocking effect. Comparing the results from different start processes, a model with respect to the shifting of reactive region within the catalyst layer is applied to e...

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Pd-induced surface structures on Si(1 1 3) have been studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). In the initial process of the Pd adsorption below 0.10 ML, Pd silicide (Pd{sub 2}Si) clusters are observed to form randomly on the surface. By increasing the Pd coverage to 0.10 ML, the clusters cover the entire surface, and an amorphous layer is formed. After annealing the Si(1 1 3)-Pd surface at 600 deg. C, various types of islands and chain protrusions appears. The agglomeration, coalescence and crystallization of these islands are observed by using high temperature (HT-) STM. It is also found by XPS that the islands correspond to Pd{sub 2}Si structure. On the basis of these results, evolution of Pd-induced structures at high temperatures is in detail discussed.

British Library Electronic Table of Contents (United Kingdom)

For optimal performances, proton exchange membrane fuel cells require fine water and thermal management. Accurate modelling of the physical phenomena occurring in the fuel cell is a key issue to improve fuel cell technology. Here, an analytic steady state diphasic 2D model of heat and mass transfer is presented. Through this model, the aim of this work is to study the influence of local events on the global performances of a fuel cell. A part of the complete model is a microscopic representation of the coupling between water transport and charge transfers in the electrodes. The thickness of the liquid layer around the reactive agglomerates is deduced from the saturation. The evolution of the quantity of water within the catalyst layer is monitored and its influence on the global performanc...

International Nuclear Information System (INIS)

Nano indentation analysis and transmission electron microscopy observation were performed to investigate a microstructural evolution and its influence on the hardening behavior in Fe-Cr alloys after an irradiation with 8 MeV Fe4+ ions at room temperature. Nano indentation analysis shows that an irradiation induced hardening is generated more considerably in the Fe-15Cr alloy than in the Fe-5Cr alloy by the ion irradiation. TEM observation reveals a significant population of the a0 dislocation loops in the Fe-15Cr alloy and an agglomeration of the 1/2a0 dislocation loops in the Fe-5Cr alloy. The results indicate that the a0 dislocation loops will act as stronger obstacles to a dislocation motion than 1/2a0 dislocation loops.

CERN Document Server

According to empirical observations, some pattern formation phenomena in driven many-particle systems are more pronounced in the presence of a certain noise level. We investigate this phenomenon of fluctuation-driven ordering with a cellular automaton model of interactive motion in space and find an optimal noise strength, while order breaks down at high(er) fluctuation levels. Additionally, we discuss the phenomenon of noise- and drift-induced self-organization in systems that would show disorder in the absence of fluctuations. In the future, related studies may have applications to the control of many-particle systems such as the efficient separation of particles. The rather general formulation of our model in the spirit of game theory may allow to shed some light on several different kinds of noise-induced ordering phenomena observed in physical, chemical, biological, and socio-economic systems (e.g., attractive and repulsive agglomeration, or segregation).

Energy Technology Data Exchange (ETDEWEB)

Water model experiments were conducted to develop a two-stage stirring method for obtaining higher yields and a more uniform distribution of graphite particles in copper alloys. This was followed by several melts for synthesis of copper-graphite alloys in which Ti was used as a wetting agent to improve the wettability of graphite in the copper melt. In the first stage, a vortex method was employed to facilitate the addition of graphite particles into the copper melt. In the second stage, a specially designed stirrer was used for uniform particle distribution while avoiding the formation of vortex in the melt. The two-stage stirring was found to considerably improve the recovery of graphite, over those obtained with the prior practice of single-stage stirring and resulting in a more uniform particle distribution. In addition, graphite recoveries increased with increasing Ti content in the range investigated. Floatation, fluidity, and directional solidification experiments were also ...

International Nuclear Information System (INIS)

The divertor 'Large Project' was conceived with the aim of demonstrating the feasibility of meeting the lifetime requirements by employing the candidate armor materials of beryllium, tungsten (W) and carbon-fiber-composite (CFC). At the start, there existed only limited experience with constructing water-cooled high heat flux armored components for tokamaks. To this was added the complication posed by the need to use a silver-free joining technique that avoids the transmutation of n-irradiated silver to cadmium. The research project involving the four Home Teams (HTs) has focused on the design, development, manufacture and testing of full-scale Plasma Facing Components (PFCs) suitable for ITER. The task addressed all the issues facing ITER divertor design, such as providing adequate armor erosion lifetime, meeting the required armor-heat sink joint lifetime and heat sink fatigue life, sustaining thermal-hydraulic and electromechanical loads, ...

Science.gov (United States)

Most palladium thin film based hydrogen gas sensors have response and recovery times that are too long to make them useful in vehicular and stationary gas leak detection applications. In contrast, a palladium-silver thin film based microcantilever (MC) hydrogen gas microsensor is reported herein with near ideal response characteristics for use in these hydrogen economy related applications. Specifically, 3-10 second response and recovery times have been measured for these sensors in contrast to previous sensor response measurements of several to tens of minutes using Pd thin film and MC based sensing techniques. The much reduced response times observed in the present study are attributed to a wet chemical Pd-Ag thin film deposition technique and a gas conditioning protocol that produces a highly nanostructured, porous film that rapidly adsorbs and desorbs H2, allowing rapid equilibration with the H2 concentration in the surrounding air. The wet chemical process and ...

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Recent research has shown that biologically inspired approaches to materials synthesis and self-assembly, hold promise of unprecedented atomic level control of structure and interfaces. In particular, the use of organic molecules to control the production of inorganic technological materials has the potential for controlling grain structure to enhance material strength; controlling facet expression for enhanced catalytic activity; and controlling the shape of nanostructured materials to optimize optical, electrical and magnetic properties. In this work, we use organic molecules to modify silver crystal shapes towards understanding the metal-organic interactions that lead to nanoparticle shape control. Using in situ electrochemical AFM (EC-AFM) as an in situ probe, we study the influence of a cationic surfactant cetyltrimethylamminobromide (CTAB) on Ag growth during electrochemical deposition on Ag(100). The results show that the organic surfactant promotes the ...

Energy Technology Data Exchange (ETDEWEB)

Alkaline fuel cells (AFCs) provide a less corrosive environment and can provide higher electrode reaction kinetics than proton exchange membrane fuel cells (PEMFCs). The alkaline media also allows for the replacement of platinum (Pt) based electrocatalysts with non-Pt electrocatalysts. Studies have shown that palladium (Pd) and silver (Ag) form a homogenous solid solution with a face-centred cubic structure within a large range of temperatures. This study described the results of an oxygen reduction reaction (ORR) on lead-silver (Pd-Ag) alloy electrodes in alkaline media. The reaction was compared with Pd and Ag electrodes. The alloys were synthesized as thin films using a sequential electroless deposition of Pd and Ag on stainless steel discs followed by an annealing procedure in an Ar stream. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterize catalyst structure, ...

Energy Technology Data Exchange (ETDEWEB)

Most of the organic electronic devices are nowadays fabricated under poor vacuum conditions. In this regard, there is only little knowledge about the impact of contamination of the metal electrode on the charge injection barrier in this kind of electronic devices. In our study we have performed X-ray and ultra violet photoemission spectroscopy (XPS, UPS) on interfaces between the organic semiconductor -sexithiophene and sputter cleaned (ideal) metals as well as contaminated (realistic) metals. As metal substrates we have used silver, gold, palladium, and platinum. These metals provide us a wide range of metal work functions from 4.2 eV for silver up to 5.5 eV for platinum. For all interfaces of -sexithiophene and contaminated metals we have observed a reduction of the interface dipole and the hole injection barrier. The charge injection barrier in all four cases is almost independent of the underlying metal (within an error of 0.2 eV) and the ...

Energy Technology Data Exchange (ETDEWEB)

A series of copolymers based on the cellulose acetate/propionate-g.co-acrylic acid system has been prepared under radiation-induced control. These copolymers have been assessed for their water-retention capacity both in an unmodified state and after ''decrystallization'' or ''neutralization'' treatments. The grafting of acrylic acid onto the cellulose acetate/propionate had little effect on the water retention power of the cellulose acetate/propionate. However, improvements to the water retentivity was obtained after ''decrystallization'' procedures had been carried out on the copolymers using selected alkali metal salts with methanol as the continuous medium. The water-retentivity of the copolymers increased with increase in the extent of grafting, though the effect is less pronounced at high graft levels. Neutralization of the functional groups of the ...

Science.gov (United States)

The effects of the structure of a carboxylic acid on the processes of oxidation and reduction of iron ions in irradiated aqueous solutions were directly observed during irradiation. The solutions contained the mono- or dicarboxylic acid, H/sub 2/SO/sub 4/, Fe(NH/sub 4/)/sub 2/(SO/sub 4/)/sub 2/ and O/sub 2/. Th e ferrous oxidation was rather independent of the acid and its concentration, but the reduction of ferric was possible in the presence of formic, oxalic, or valeric acid only. The radical formed from the valeric acid acts similar to those formed from hydrocarbons. The G-values of oxidation and reduction of the iron ions were established. The molar extinction coefficients for oxalic and malonic complexes of ferric ions were determined. (auth)

Energy Technology Data Exchange (ETDEWEB)

To determine if barbiturates would protect brain at high doses of radiation, survival rates in rats that received whole-brain x-irradiation during pentobarbital- or lidocaine-induced anesthesia were compared with those of control animals that received no medication and of animals anesthetized with ketamine. The animals were shielded so that respiratory and digestive tissues would not be damaged by the radiation. Survival rates in rats that received whole-brain irradiation as a single 7500-rad dose under pentobarbital- or lidocaine-induced anesthesia was increased from between from 0% and 20% to between 45% and 69% over the 40 days of observation compared with the other two groups (p less than 0.007). Ketamine anesthesia provided no protection. There were no notable differential effects upon non-neural tissues, suggesting that pentobarbital afforded protection through modulation of ambient neural activity during radiation exposure. Neural suppression during high-dose cranial irradiation ...

Energy Technology Data Exchange (ETDEWEB)

Current bioartificial extra-corporeal systems are bioreactors where cells are separated from the surrounding media by porous polymeric membranes. The present work focuses on the design of membranes that allow the differential diffusion of plasma metabolites and proteins such as immunoglobulin (IgG). This design will improve catabolites removal and reduce possible immune response and virus infection. We demonstrate the feasibility to synthesize the hydrogels confined to the macroporous structure of membranes by radiation-induced in situ polymerization. The hollow-fiber membranes were soaked in aqueous monomeric solution, rinsed and irradiated while submerged in oil. This procedure confined the hydrogel to the void internal volume of the pores of the membrane. Hydrogels of polyacrylamide and polyHEMA were synthesized this way by irradiation at 10 kGy. Hydraulic permeability and diffusion of glucose, albumin and IgG were measured in these hydrogel-filled membranes. ...

International Nuclear Information System (INIS)

The atomic explosions in Hiroshima and Nagasaki made the name radiation itself become a nightmare. Notwithstanding this, radiation continued to serve the mankind specially in diagnosis of several human diseases and in the treatment of intractable malignancies. With their latest research tools biologists have now shown a significant shift in the earlier paradigm; even the concept that radiation initiates cancer appears to be no longer tenable. On the contrary, selective radiation doses inhibit growth of cancer cells and radiation in combination with many chemotherapeutic drugs, radiosensitizing chemicals and/or hyperthermia, is emerging as a new modality for cancer treatment which offers high therapeutic advantages. In addition, the deleterious effects of radiation can now be strategically counter poised by the use of many drugs and chemicals. This has been possible by the newer insights gained in the mechanism of biological effects of radiation. The fate of ...

International Nuclear Information System (INIS)

In experiments designed to detect new mutations affecting hemoglobin, we irradiated the male or female parent in reciprocal crosses of two mouse strains that differ in alleles at the hemoglobin (Hba, Hbb) loci as well as at five other specific loci. Offspring were analyzed for hemoglobin properties (electrophoretic pattern, solubility, crystal pattern), serum albumin differences, erythrocyte lysis, reticulocyte count, and external appearance. Five hemoglobin variants were found among the mutants. In three, the genetic contribution from the irradiated father was not expressed with regard to the #alpha#-chain; one carried a tandem duplication (the first known case in the mouse) involving Hbb; and one probably resulted from double nondisjunction of chromosome 7. The finding that major chromosome aberratios can mimic hemoglobin mutations indicates the need, in similar experiments, to follow F_1 screening with thorough cytogenetic analysis. The variants in which there is nonexpression of ...

Energy Technology Data Exchange (ETDEWEB)

Wood sawdust has been applied to manufacture the sawdust-clay-plastic composite (SDCPC) by radiation process for the purpose of disposing large amount of wood sawdust waste material. The process comprises the impregnation of liquid vinyl monomers into the completely dried molded sawdust-clay specimens followed by exposure to Co-60 gamma-radiation to induce graft-copolymerization of the impregnated vinyl monomers onto the sawdust-clay matrix. The comonomer system of unsaturated polyester and vinyl compounds was found to be the ideal impregnating monomer for the preparation of the SDCPC from the viewpoint of the technological and economical advantages. The SDCPC material has a variety of the sawdust content which enables the composite to have wide range of mechanical properties, e.g., 410 to 1100 kg/cm/sup 2/ in compressive strength, 120 to 380 kg/cm/sup 2/ in tensile strength and 0.32 to 4.41 kg/mm/sup 2/ in static bending strength. The SDCPC having higher content of clay (more than 50% ...

Energy Technology Data Exchange (ETDEWEB)

The in situ assembly states of the glucose transport carrier protein in the plasma membrane and in the intracellular (microsomal) storage pool of rat adipocytes were assessed by studying radiation-induced inactivation of the D-glucose-sensitive cytochalasin B binding activities. High energy radiation inactivated the glucose-sensitive cytochalasin B binding of each of these membrane preparations by reducing the total number of the binding sites without affecting the dissociation constant. The reduction in total number of binding sites was analyzed as a function of radiation dose based on target theory, from which a radiation-sensitive mass (target size) was calculated. When the plasma membranes of insulin-treated adipocytes were used, a target size of approximately 58,000 daltons was obtained. For adipocyte microsomal membranes, we obtained target sizes of approximately 112,000 and 109,000 daltons prior to and after insulin treatment, respectively. In the case of ...

International Nuclear Information System (INIS)

Total-dose irradiation seriously damages MOS devices and their circuit performance. Threshold voltage shifts, transconductance degradation and increase in off-state leakage current are generally observed for irradiated devices. These instabilities are essentially due to positive and/or negative charge trapping in SiO_2 and interface trap generation at the SiO_2/Si interface. Radiation hardening of CMOS VLSIs is to eliminate these trapping effects, and for this purpose, special considerations for fabrication processes and layout design are necessary. In this paper, basic mechanisms for radiation-induced charge trapping and related effects on MOS devices are reviewed. Also discussed are radiation-hardening technologies from both fabrication-process and layout-design viewpoints. Using these technologies, 1 #mu#m radiation-hard CMOS gate arrays have been successfully developed. Experimental data taken for 2k-gate test chips indicate that radiation hardness of these ...

Energy Technology Data Exchange (ETDEWEB)

The adverse effect of moisture diffusion on the properties of wood has been one of the main weaknesses of wood. Using a gamma irradiation method, wood-polymer composites have been produced which exhibit significant improvement in mechanical properties like compression, creep deformation and creep rupture particularly at high humidity. It has been thought that the impregnation of polymer into the wood has affected the moisture diffusion in the wood, so that its adverse effects on the mechanical properties has been reduced. In this report the apparent diffusion coefficients of a Ramin wood impregnated with varying amounts of polymethyl methacrylate (PMMA) were determined using a Fick's law approach. An initial linear relationship was found for impregnation of up to 70% PMMA, after which the diffusion coefficient levels off to a maximum value, for the three environmental relative humidity levels of 40, 60 and 90({plus minus}5)%. The phenomenon could be explained by means of a ...

Energy Technology Data Exchange (ETDEWEB)

The electrical conductivity of Vitox-alumina (99.2%), Wesgo-alumina (99.9%) and AlN (99.6%) has been measured during and after irradiation with an experimental set-up which allows fusion relevant loading conditions. All irradiations were performed in high vacuum at 450 C using a 104 MeV {alpha}-particle beam with an applied DC electric field of 100 kV/m. In the high purity Vitox-alumina the in-situ and postirradiation bulk conductivities {sigma} and {sigma}{sub 0} show the highest irradiation induced electrical breakdown ever observed. The saturation level near 4 x 10{sup -2} ({Omega}m){sup -1}, reached already after 0.015 dpa (O-sublattice), is already above the critical value necessary to avoid MHD pressure drop with 10 {mu}m coatings in flowing liquid metal coolants. Under the same conditions no radiation induced electrical degradation at all has been found in Wesgo-alumina and AlN. (orig.).

International Nuclear Information System (INIS)

Thermoluminescence (TL) dosimetry was used to measure dose effects on the raw stock material of borosilicate container glass from different geographical locations. Effects were studied at times up to 60 days post-irradiation at doses from 0.15 to 20 Gy. The minimum detectable dose using this technique was estimated to be 0.15 Gy which is roughly equivalent to a 24 hr irradiation 1 cm from a 50 ng source of 60Co. Two peaks were identified in the TL glow curve, a relatively unstable peak around 125 C and a more stable peak around 225 C. Differences in TL glow curve shape and intensity were also observed for the glasses from different geographical origins. We investigate radiation induced defects in glass to further develop the technique of intrinsic dosimetry - the measurement of the total absorbed dose received by the walls of a container holding radioactive material. Intrinsic dosimetry is intended to be used as an interrogation tool to provide ...

Energy Technology Data Exchange (ETDEWEB)

For an assessment of the future US spallation neutron source (SNS) target performance, radiation induced hardening and microstructural evolution were investigated as a function of ion dose for EC316LN stainless steel. Irradiation was carried out using 3.5 MeV Fe{sup +}, 360 keV He{sup +}, and 180 keV H{sup +} simultaneous ion-beams at 200 deg. C to simulate the damage, He and H production in the SNS target vessel wall. At low dose (< 1 dpa), the predominant defects were black dots whose number density saturated rapidly within a few dpa. This was followed by the evolution of interstitial loops whose number density saturated below 15 dpa. Although He-bubbles were not visible, severely scalloped loops suggested that the implanted He/H atoms existed in the form of small clusters. Comparison with reported neutron irradiation data showed that hardening and ductility loss occurred mostly in the black dot regime (< 1 dpa), but that good ...

International Nuclear Information System (INIS)

The application of robotics for repair, refurbishing or dismantling of nuclear installations implies eventually severe radiation resistance requirements on embarked components and subsystems. This is particularly critical when optical sensing is considered. Optoelectronic components and optical fibers are indeed quite sensitive to radiation, and without special design are rapidly out-of-operation in such an environment. This paper reports the results of a series of #gamma# irradiation experiments on such devices, and identify their behavior under radiation. Test results show that carefully selected optical fibers can keep their radiation induced attenuation lower than 0.3 dB/m even up to a total dose of 10 MGy. Temperature annealing can even lower this attenuation down to 0.1 dB/m. On the other hand, commercially available light emitting diodes and photodiodes present attenuations figures up to 15 dB, even after a gamma irradiation as low as ...

Energy Technology Data Exchange (ETDEWEB)

Aluminum nitride has been proposed as electrically insulating coating in connection with blankets made of vanadium alloys. Irradiations were performed with an applied DC electric field of 100 kV/m, using a 104 MeV {alpha}-particle beam. The dose achieved were 0.1 dpa at 300 C, 0.05 dpa at 400 C, and 0.06 dpa at 500 C. The out-of-beam conductivity {sigma}{sub 0} decreased at all temperatures employed during early stage of irradiation. Before 0.02 dpa had been reached, {sigma}{sub 0} dropped to low values of typically (2-4) x 10{sup -11} ({Omega} m){sup -1}. Although a moderate increase can be observed during further irradiation, {sigma}{sub 0} remained below the initial value of the unirradiated specimen for all temperatures. That is, there is no significant evidence for radiation induced electrical degradation. The in-beam conductivity {sigma}, measured continuously during irradiation, also decreased by at least one order of magnitude. Relevant ...

Energy Technology Data Exchange (ETDEWEB)

Effect of radiation dose and carbon nanotubes (CNT) on the mechanical properties of standard Malaysian rubber (SMR) was investigated in this study. SMR nanocomposites containing 1-7 phr CNT were prepared using the solvent casting method and the nanocomposites were radiated at doses of 50-200 kGy. The change in mechanical properties, especially, tensile strength (Ts), elongation at break (Eb), hardness and tensile modulus at 100% elongation (M{sub 100}) were studied as a function of radiation dose. The structure and morphology of reinforced natural rubber was investigated by FESEM, TEM and AFM in order to gain further evidence on the radiation-induced crosslinking. It was found that the Ts, M{sub 100} and the hardness of the SMR/CNT nanocomposites significantly increased with radiation dose; the elongation at break exhibited an increase up to 100 kGy, and a downward trend thereafter. Results on gel fraction further confirmed the crosslinking of SMR/CNT ...

International Nuclear Information System (INIS)

Alloy HT-9 is being used for both duct and cladding applications in advanced liquid-metal reactor (LMR) experiments. This tempered martensitic steel was selected for use as an LMR core component material primarily because of its excellent resistance to radiation-induced swelling. Experiments conducted in the Fast Flux Test Facility (FFTF) at 410 degree C and exposures in the range of 150 to 175 displacements per atom (dpa) have shown that Ht-9 exhibits only a 0.2 to 0.3% increase in volume. Cold-worked austenitic steels exhibit volumetric increases of 20 to 30% at 410 degree C, Alloy HT-9 is being used for a series of fuel pin experiments in the FFTF, and these tests have achieved a burnup of 175 MWd/kg metal and a fluence of 25 x 10"2"2 n/cm"2 (E > 0.1 MeV) without fuel pin breach. The high confidence placed in HT-9 is based on a wide series of in- and ex-reactor experiments. Test results for these experiments are summarized in this paper.

International Nuclear Information System (INIS)

The work scope of 'Biological Research for the Radiation Protection' had contained the research about ornithine decarboxylase and its controlling proteins, thioredoxin, peroxiredoxin, S-adenosymethionine decarboxylase, and glutamate decarboxylase 67KD effect on the cell death triggered ionizing radiation and H_2O_2(toxic agents). In this study, to elucidate the role of these proteins in the ionizing radiation (or H_2O_2)-induced apoptotic cell death, we utilized sensesed (or antisensed) cells, which overexpress (or down-regulate) RNAs associated with these proteins biosynthesis, and investigated the effects of these genes on the cytotoxicity caused by ionizing radiation and H_2O_2(or paraquat). We also investigated whether genisteine(or thiamine) may enhance the cytotoxic efficacy of tumor cells caused by ionizing radiation (may enhance the preventing effect radiation or paraquat-induced damage) because such compounds are able to potentiate the cell-killing or cell protecting effects. ...

Energy Technology Data Exchange (ETDEWEB)

The overall objective of this project has been to develop immunochemical methods to quantitate unique DNA base damages in order to facilitate studies on radiation-induced damage production and repair. Specifically, we have been using antibodies raised to damaged bases to quantitate unique lesions in model systems in order to evaluate their potential biological consequences. Our approach has been to synthesize modified nucleotides or nucleosides, conjugate them to protein carriers, and use the conjugates as immunogens in rabbits or to prepare monoclonal antibodies. We have been studying damages that are stable radiolysis products found in X-irradiated DNA and thus of potential biological consequence. Our aim is to build an in vitro and in vivo data base on the interactions between model DNA lesions and such cellular enzymes as DNA polymerases and repair endonucleases. Initial studies have focused on pyrimidine ring saturation products (thymine glycol.and ...

Energy Technology Data Exchange (ETDEWEB)

A study of two forest areas in India investigated how much energy is wasted when high stumps are left after trees are cut to produce wooden boxes for packing the apple harvest. Measurements of the stumps determined the total wood pulp wasted, which was 1191 tons during 1981. The calorific value of the stumps would supply a year's cooking and heating fuels for 747 families of five. Additional fuel is wasted by abandoning the branches and tree tops which are unsuitable for box construction. 5 references, 4 tables.

Energy Technology Data Exchange (ETDEWEB)

This paper described the application of an AC surface probe, similar to presently used eddy current probes, to the measurement of DC transport critical currents and critical state dissipation in high {Tc} superconductors. It has been shown that the probe can provide quantitative measurement of the full field penetration in superconducting samples by measuring the response of AC induced screening currents for superconducting materials in the form of tapes with overlayers of silver. In this manner, the AC probe can be used to replace the contact DC probe for determining critical currents in a noncontacting and local manner suitable for scanning over or along the sample.

Energy Technology Data Exchange (ETDEWEB)

This paper described the application of an AC surface probe, similar to presently used eddy current probes, to the measurement of DC transport critical currents and critical state dissipation in high [Tc] superconductors. It has been shown that the probe can provide quantitative measurement of the full field penetration in superconducting samples by measuring the response of AC induced screening currents for superconducting materials in the form of tapes with overlayers of silver. In this manner, the AC probe can be used to replace the contact DC probe for determining critical currents in a noncontacting and local manner suitable for scanning over or along the sample.

Energy Technology Data Exchange (ETDEWEB)

A new lens was installed in the laser; the laser power was lowered and solar cells were made at different power levels. The concentration of the silver neodecanoate solution was changed to reduce linewidth. A cell fabrication run was completed using low-resistivity float-zone silicon. Experiments were initiated to investigate the use of titanium organometallic film, which not only forms an AR coating with a 400/sup 0/C hard bake, but may also help in bypassing front-metal evaporation because of high-reactivity of Ti with silicon. Progress in these areas is discussed.

Science.gov (United States)

In this study, different proportions of silver-palladium alloy used as an inner electrode are adopted to fabricate (Zn,Mg)TiO3-based multilayer ceramic capacitors. Effects of sintering temperature, and measuring frequency on the dielectric properties of the samples with different proportions of the Pd-Ag inner electrode are investigated. The continuity of the inner electrode and the proportion of Pd-Ag of the inner electrode of samples sintered at different temperatures play important roles in determining the dielectric properties.

Energy Technology Data Exchange (ETDEWEB)

Population residing in the northern part of the Chelyabinsk oblast and the south eastern part of the Sverdlovsk oblast of Russia affected to accidental exposure since 1957. The territory (East Ural Radioactive Trace - EURT) was contaminated after explosion of container with highly radioactive wastes at the Mayak Production Association. Studies of health effects of exposure in the southern, head part of EURT are conducted in the Ural Research and Practical Center of Radiation Medicine (U.R.P.R.M.). In the 1990's U.R.P.C.R.M. formed a cohort of EURT within Chelyabinsk oblast (14,500 cases and 19,400 external controls). The cohort was followed in 1957-1987 and the results of the study are discussed by Crestinina et al. First results of study on exposure late health effects among rural population in the northern part of the EURT are presented in this paper. Firstly, or the period 1958-2000 a statistically significant increase in cancer mortality associated with accidental exposure ...

Science.gov (United States)

Silver iron oxide nanoparticles of fairly small size (average diameter approximately 1 nm) with narrow size distribution have been synthesized by the interaction of colloidal beta- Fe2O3 and silver nanoparticles. The surface morphology and size of these particles have been analyzed by using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Their structural analysis has been carried out by employing x-ray diffraction (XRD), selected-area electron diffraction (SAED), optical and infrared (IR) spectroscopic techniques. The ageing of these particles exhibits the formation of self-assembly, possibly involving weak supramolecular interactions between Ag(I)O4 and Fe(III)O4 species. These particles display the onset of absorption in the near-infrared region and have higher absorption coefficient in the visible range compared to that of its precursors. Magnetic measurements ...

Energy Technology Data Exchange (ETDEWEB)

Laser-assisted processing techniques for producing high-quality solar cell metallization patterns have been investigated, developed, and characterized. During the early stages, preliminary investigations were carried out on a variety of promising laser-assisted metallization schemes, and the best of these was selected for further development. A comprehensive literature search initially yielded information on state-of-the-art laser-assisted techniques for metal deposition such as laser chemical vapor deposition and laser photolysis of organometallics, as well as laser-enhanced electroplating. Initial experiments on laser-enhanced electroplating yielded very promising results with linewidths as narrow as 25 ..mu..m and local plating speeds as high as 12 ..mu..m/s being achieved. Metal deposition experiments were carried out utilizing laser-assisted pyrolysis of a variety of metal-bearing polymer films and metallo-organic inks spun onto silicon substrates. Argon-ion laser decomposition of ...

Energy Technology Data Exchange (ETDEWEB)

The feasibility of using three different solid fuels in chemical-looping combustion (CLC) has been investigated using NiO as oxygen carrier. A laboratory fluidized-bed reactor system for solid fuel was used, simulating a chemical-looping combustion system by exposing the sample to alternating reducing and oxidizing conditions. In each reducing phase 0.2g of fuel was added to the reactor containing 20g oxygen carrier. The experiments were performed at 970{sup o}C. Compared to previously published results with other oxygen carriers the reactivity of the used Ni-particles was considerably lower for the high-sulphur fuel and higher for the low-sulphur fuel. Much more unconverted CO was released and the fuel conversion was much slower for high-sulphur fuel such as petroleum coke, suggesting that the nickel-based oxygen carrier was deactivated by the presence of sulphur. The NiO particles also showed good reactivity with methane and a syngas mixture of 50% H{sub 2} and 50% CO. For all ...

Energy Technology Data Exchange (ETDEWEB)

The goal of this work was to develop a process flow diagram to economically produce a clean-burning fuel from fine Illinois coal. To accomplish this, the process of pelletizing fine coal with calcium hydroxide, a sulfur capturing sorbent, was investigated. Carbonation, which is the reaction of calcium hydroxide with carbon dioxide (in the presence of moisture) to produce a bonding matrix of calcium carbonate, was investigated as a method for improving pellet quality and reducing binder costs. Proper moisture level is critical to allow the reaction to occur. If too much moisture is present in a pellet, the pore spaces are filled and carbon dioxide must diffuse through the water to reach the calcium hydroxide and react. This severely slows or stops the reaction. The ideal situation is when there is just enough moisture to coat the calcium hydroxide allowing for the reaction to proceed. The process has been successfully demonstrated on a pilot-scale as a method of hardening iron ore ...

International Nuclear Information System (INIS)

Current advanced CMOS source/drain engineering involves the use of amorphizing implants with 3D geometry. Upon annealing, the induced transient enhanced diffusion (TED) can only be accurately predicted if the amorphized region is correctly modeled, as well as the formation and evolution of extended defects, particularly 3 1 1's and dislocation loops. In addition to the extended defects, already modeled in the atomistic kinetic Monte-Carlo simulator DADOS, we have developed a physically based modeling approach for the implant-induced damage build-up, amorphization and recrystallization, suitable to handle device-size process simulation. It is based on amorphous pockets (3D, irregular shape agglomerates of an arbitrary number of interstitials and vacancies, plus trapped impurities) with a size-dependent activation energy for recombination. The model is able to reproduce experimental aspects like the crystal-amorphous transition temperature and the super linear ...

Energy Technology Data Exchange (ETDEWEB)

A thermal analyzer-differential scanning calorimeter-mass spectrometer (TG-DSC-MS) was used to study oxygen carriers (OC) for their potential use for the application of chemical looping combustion (CLC) to solid fuels. Reaction rates, changes in reaction rates with repeated oxidation-reductions, exothermic heats during oxidation, and the effect of changing reduction gas compositions were studied. Oxidation rates were greater than reduction rates and reaction rates were reproducible through multiple oxidation-reduction cycles except where agglomeration occurred with powders. Iron oxide (Fe{sub 2}O{sub 3} powder) and iron-based catalysts were found suitable for CLC of solid fuels having rapid reduction rates which increased with higher reducing gas concentrations. Fe{sub 2}O{sub 3} powder was used to oxidize a high carbon coal char in an inert gas removing 88% of the carbon from the char. Other properties such as cost and durability indicated iron oxide OCs potential ...

Energy Technology Data Exchange (ETDEWEB)

The objective of this work is the measurement of two-phase flow parameters to support development of constitutive relationships for the HANARO/MAPLE type finned fuel using Real-Time Neutron Radiography (RTNR). A single element finned Fuel Element Simulator was used with R134a Freon flow. To observe the effect of a spacer device on void distribution, single pin tests were performed with and without a spacer. By analyzing the RTNR images using image processing, the effects of the spacer on the time-averaged and instantaneous void fraction distributions were studied. For the experimental results without a spacer, the time-averaged local void distribution is radially asymmetric and the degree of void fluctuation increases with a decreasing frequency along the heated channel, where the observed asymmetry may be caused by flow induced vibration. For the experimental results with a spacer, the spacer clearly limits any significant vibration and the local void distribution becomes more ...

International Nuclear Information System (INIS)

Local properties and heat transfer have been investigated in a NaK-nitrogen two-phase flow in a vertical tube under transverse magnetic field. An objective two-phase flow regime identification was also carried out systematically, using the probability distribution function of two-phase electromagnetic flowmeter signals. The application of a magnetic field was bound to bring about a drastic change in the void fraction profile, i.e., asymmetric profile perpendicular to the field direction. This effect was more remarkably observed in bubbly flows. The magnetic field was also observed to decrease the number of bubbles, by promoting the agglomeration of small bubbles into larger ones and also break-up of large slugs, and, thus, to shift the flow regime boundaries. It has been also shown that the two-phase Nusselt number increases in bubbly flows, while it decreases in slug flows. This trend however reduces in the presence of a magnetic field.

International Nuclear Information System (INIS)

The measurement of two-phase flow parameters for development of constitutive relationships for the HANARO/MAPLE type finned fuel using Real-Time Neutron Radiography (RTNR) is discussed in this paper. A single element finned Fuel Element Simulator (FES) was used with Freon 134a as the working fluid. To observe the effect of a spacer device on void distribution, single pin tests were performed with and without a spacer present. By analyzing the RTNR images using image processing, the effects of the spacer on the time-averaged and instantaneous void fraction distribution were studied. For the experimental results without a spacer, the time-averaged local void distribution is radially asymmetric and the degree of void fluctuation increases with a decreasing frequency along the heated channel, where the observed asymmetry may be caused by flow induced vibration. For the experimental results with a spacer, the spacer clearly limits any significant vibration and the local void distribution ...

Energy Technology Data Exchange (ETDEWEB)

Chemical-looping combustion is a promising technology for the combustion of gas or solid fuel with efficient use of energy and inherent separation of CO{sub 2}. Chemical-looping combustion of methane with calcium sulfate as a novel oxygen carrier was conducted in a laboratory scale fixed bed reactor. The effects of reaction temperature, gas flow rate, sample mass, and particle size on reduction reactions were investigated and an optimum operating condition was determined. The results show that this novel oxygen carrier has a high reduction reactivity and stability in a long-time reduction/oxidation test. The conversions of CH{sub 4} increased with a higher temperature, smaller gas flow rate, larger sample mass and smaller particle size. The suitable reaction temperature seems to be around 950 deg. C. Low temperatures lead to a low CH{sub 4} conversion, but a significant SO{sub 2} formation was observed at a higher temperature. The release of SO{sub 2}, CO, H{sub 2} via a series of side ...

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An in situ synthesis of ZnS and CdS quantum dots (QDs) in an aqueous solution of sodium hyaluronate (Hyal) produced foils emitting light on excitation with a UV light. The wavelength of emission was only slightly QDs size and more QDs concentration dependent and reached up to {approx}320 nm in the case of ZnS and {approx}400-450 nm in the case of CdS. Nanoparticles remained as non-agglomerated 10-20 nm nanoclusters. CdS/Hyal and ZnS/Hyal-QDs biocomposites were characterized using photoluminescence (PL), IR spectrometric techniques, and Transmission Electron Microscopy (TEM). The absolute molecular weights, radii of gyration, R{sub g}, and thermodynamic properties of the obtained foils are given. Electric resistivity studies performed for the hyaluronic foil in the 100-1000 V range have revealed that the hyaluronate foil has very weak conducting properties and QDs only insignificantly affect those properties as QDs practically did not interact with the foil. Size ...

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The behavior of melter feed (a mixture of nuclear waste and glass-forming additives) during waste-glass processing has a significant impact on the rate of the vitrification process. We studied the effects of silica particle size and sucrose addition on the volumetric expansion (foaming) of a high-alumina feed and the rate of dissolution of silica particles in feed samples heated at 5 C/min up to 1200 C. The initial size of quartz particles in feed ranged from 5 to 195 {micro}m. The fraction of the sucrose added ranged from 0 to 0.20 g per g glass. Extensive foaming occurred only in feeds with 5-{micro}m quartz particles; particles {ge}150 {micro}m formed clusters. Particles of 5 {micro}m completely dissolved by 900 C whereas particles {ge}150 {micro}m did not fully dissolve even when the temperature reached 1200 C. Sucrose addition had virtually zero impact on both foaming and the dissolution of silica particles. Over 100 sites in the United States are currently tasked with the storage ...

British Library Electronic Table of Contents (United Kingdom)

We investigated phase transition of ilmenite-type AgSbO3 to pyrochlore by post-heat treatment and the synergy effect of the mixed phases of AgSbO3 on the photocatalytic activities to enhance the activities. The AgSbO3 with an ilmenite structure was prepared by a cation-exchange method. Phase transition from the ilmenite to pyrochlore occurred by proper control of post-heat treatment. The sample that was obtained by post-heat treatment of ilmenite-type AgSbO3 at 660^oC for 3h consisted of both of the ilmenite and pyrochlore phases, and the sample at 685^oC for 4h mainly consisted of the pyrochlore phase. Together with an increase in the ratio of the pyrochlore phase, the optical absorption spectra blue-shifted. The band gaps of single phases of the ilmenite and the pyrochlore were 2.4 and 2...

Energy Technology Data Exchange (ETDEWEB)

The photoluminescence intensity of an optical emitter changes when placed in close proximity to a noble-metal nanoparticle, due to two contributions. First, the optical near-field of the nanoparticle leads to a change in excitation rate of the emitter. Secondly, the emission efficiency is changed due to an optical energy transfer from the emitter to the metal nanoparticle, which provides additional radiative and non-radiative decay channels. In this work we investigate the photoluminescence of Sm{sup 3+} ions, which are embedded in SiO{sub 2}. The photoluminescence spectrum of ions in proximity to single silver and gold nanoparticles is measured. The influence of the spectral position of the nanoparticle plasmon peak on the photoluminescence yield will be discussed and compared with model calculations.

Energy Technology Data Exchange (ETDEWEB)

In this work, we have investigated the capability of different bimetallic nanoparticle alloy combinations to be used in fibre optic temperature sensing based on the technique of surface plasmon resonance (SPR). The metals considered for the present analysis are silver, gold and aluminium. The analysis is derived mainly from the thermo-optic effect along with some fundamental concepts of metal optics such as surface scattering, phonon-electron scattering and electron-electron scattering. The performance of the sensor with three different bimetallic nanoparticle alloy combinations is evaluated and compared, numerically, in terms of its sensitivity and accuracy. On the basis of the comparison and some logistic criterion, we predict the best possible bimetallic alloy combination along with a requisite alloy composition ratio that simultaneously provides higher values of both sensitivity and accuracy which is not possible with any single metallic nanoparticle layer.

International Nuclear Information System (INIS)

An experiment on the K#beta#/K#alpha# characteristic X-ray intensity ratio in silver was performed at VEC Centre, Calcutta using the #alpha#-beams at energies 40 MeV and 50 MeV employing a Si(Li) detector system on-line. The results show that the K#beta#/K#alpha# X-ray intensity ratio at energies 40 and 50 MeV are 0.215 #+-# 0.006 and 0.216 #+-# 0.006, respectively, which indicates no change with beam energy and in accordance with the earlier reports. The present experiment shows the feasibility of studying the K#beta#/K#alpha# ratios as a function of beam energy in different regions of periodic table. Experiments in elements belonging to the 3d shell and their compounds are suggested to look for the chemical effects and their dependence on #alpha#-energy. (author). 7 refs.

Energy Technology Data Exchange (ETDEWEB)

Inert markers (evaporated tungsten and silver) were used in growth studies of silicides formed both by thermal annealing and by ion mixing in the Ni/Si, Pd/Si, and Cr/Si systems. The markers were initially imbedded inside silicides and backscattering spectrometry was used to determine the marker displacement after different processing conditions. The results obtained in thermal annealing are quite consistent with that found in previous investigations. Ni is the dominant diffusing species in Ni/sub 2/Si, while Si is the diffusing species in CrSi/sub 2/. In Pd/sub 2/Si, both Pd and Si are moving species with Pd the faster of the two. In contrast, in growth of silicides by ion irradiation Si is the faster diffusing species in all three systems.

British Library Electronic Table of Contents (United Kingdom)

The comprehensive theoretical and experimental study of the adsorption of water and methanol molecules on active sites (carboxyl and phenol hydroxyl groups) on the graphitized thermal carbon black is performed. It is shown that microclusters formed upon the adsorption of these molecules on such sites are characterized by the cyclic structure comprising 4?5 molecules similar to that whose existence was revealed previously in liquid water and on the surface of silver iodide. The analysis of the studied adsorption clusters demonstrated that the formation of such cycles is governed primarily by the hydrogen bonding; however, a definite role is played also by energy effects associated with the changes in the state of molecular motion during adsorption. It is shown that the generalized Langmuir ...

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The distribution of /sup 35/S-sulfate and /sup 3/H-glucosamine in the angular region of the hamster was studied by light and electron microscopic autoradiography following intraperitoneal injection of these compounds to hamsters. Exposed silver grains of /sup 35/S-sulfate were concentrated in the trabecular meshwork, sclera, and cornea, and grains of /sup 3/H-glucosamine were localized in the trabecular region. The radioactivity of both isotopes was observed in the Golgi apparatuses of the endothelial cells of the angular aqueous plexus and the trabecular meshwork. The grains were noted over the entire cytoplasm, except for the nucleus, and then were incorporated into the amorphous substance and collagen fibers in the region adjacent to the angular aqueous sinus. These results suggest that endothelial cells in the angular region synthesize and secrete the sulfated glycosaminoglycans and hyaluronic acid.

International Nuclear Information System (INIS)

The themal neutron sensitivities of SEI and Toshiba FD-P10-7 radiophotoluminescent silver activated metaphosphate glass dosimeters have been measured and studied theoretically. The graphite thermal neutron column attached to the AEEW reactor NESTOR was utilised as a source of thermal neutrons with minimal fast neutron and gamma-ray contamination. Both the neutron removal and gamma correction measurement techniques were applied and these gave consistent results. It was found that the thermal neutron sensitivity of the Toshiba dosimeters is comparable to the most neutron intensitive thermoluminescent materials available. Because of their larger size and higher silver concentration, however, SEI dosimeters are an order of magnitude more neutron sensitive. The neutron sensitivity of FD-7 glass has not been reported previously, whereas in the case of SEI glass, there exists a modest body of previous work on dosimeters of nominally identical ...

International Nuclear Information System (INIS)

This paper describes the unique challenges involved in achieving compliance with the Resource Conservation and Recovery Act (Public Law 94-580) Land Disposal Restrictions (LDR) treatment standards for four types of mixed wastes generated throughout the U.S. Department of Energy (DOE) complex: (1) radioactively contaminated lead acid batteries; (2) radioactively contaminated cadmium-, mercury-, and silver-containing batteries; (3) mercury-bearing mixed wastes; and (4) radioactive lead solids. For each of these mixed waste types, the paper identifies the strategy pursued by DOE's Office of Pollution Prevention and Resource Conservation Policy and Guidance (EH-43) in coordination with other DOE elements and the U.S. Environmental Protection Agency (EPA) to meet the compliance challenge. Specifically, a regulatory interpretation was obtained from EPA agreeing that the LDR treatment standard for wastes in the D008 'Radioactive Lead Solids' sub-category applies to ...

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Although the intracellular ultrastructural processing of epidermal growth factor (EGF) and its receptor have been described in cell culture systems, very few studies have examined this phenomenon in intact tissues. We have examined the ultrastructural and biochemical handling of (/sup 125/I)EGF in the epidermis and hair follicle bulb of intact, viable, 3- to 5-day-old rat skin the EGF receptor distribution of which has already been documented and in which EGF has been shown to be biologically active. After incubation of explants with 10 nM (/sup 125/I)EGF for 2.5 h at 25 degrees or 37 degrees C, radiolabel was detected over the basal cells of the epidermis and hair follicle outer root sheath, confirming previous light microscope observations. More specifically, silver grains were observed near coated and uncoated plasma membrane and coated membrane invaginations, Golgi apparatus, lysosomal structures, and nuclei. Sodium azide inhibited internalization of label, ...

Energy Technology Data Exchange (ETDEWEB)

Hyaluronic acid (HA) is a significant component of the extracellular matrix (ECM), particular interest being shown herein in synovial fluid. The present study aims to investigate the degrading effects of X-ray radiation on HA at radiotherapy doses. Measurements of viscosity and shear stresses on HA solutions have been made at different shear rates using various types of viscometer for different concentrations in the range 0.01-1% w/v of HA. The HA has been subjected to doses of 6 MV photon radiation ranging from 0 to 20 Gy, the major emphasis being on doses below 5 Gy. It is found that there is a dose-dependent relationship between viscosity and shear rate, viscosity reducing with radiation dose, this being related to polymer scissions via the action of radiation-induced free radicals. The dependency appears to become weaker at higher concentrations, possibly due to the contribution to viscosity from polymer entanglement becoming dominant over that from mean ...

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In this paper we discuss the results of thermoluminescence (TL) studies carried out on freshly quenched crystals of KBr doped with {approx} 50 ppm of Eu{sup 2+} ions which were X-irradiated at room temperature. The TL glow curve of this phosphor material consists of three glow peaks at 355, 376 and 398 K whose intensities increased as a function of X-irradiation time. The TL glow peaks were analyzed by the total curve-fitting method in order to obtain the characteristic parameters; activation energy, pre-exponential factor and kinetic order. The spectral character of the emission recorded during thermoluminescence was found to be the same for all glow peaks and consists of a broad band centered at {approx} 420 nm. It is proposed that the model of the TL process most consistent with our experimental results is one in which the Eu{sup 2+} impurity acts as an electron trap during the irradiation process and that the radiation induced center ...

International Nuclear Information System (INIS)

Beagle dogs were given single, whole-body "6"0Co gamma-radiation exposures at one of three prenatal (8, 28, or 55 days postcoitus) or three postnatal (2, 70, or 365 days postpartum) ages to evaluate the relative radiosensitivity of various stages of brain development. A total of 387 dogs received mean doses ranging from 0.16 to 3.83 Gy, and 120 dogs were sham-irradiated. Groups of dogs were sacrificed at preselected times from 70 days to 11 years of age. Brain weight decreased significantly with increasing dose in dogs irradiated at 28 or 55 days postcoitus or at 2 days postpartum. Irradiations at 28 days postcoitus were dramatically more effective in causing a reduction in brain weight than those at 55 days postcoitus or 2 days postpartum. Among dogs given 1.0 Gy or more and followed for up to 4 years, there was a radiation effect evident at all three sensitive exposure ages. Among dogs given lower doses and followed for up to 11 years, there was a significant decrease in brain weight ...

International Nuclear Information System (INIS)

The radiation decimal reduction dose (D_1_0) of toxigenic Vibrio cholerae O1 El Tor, Inaba was determined in vitro (0.13 kGy) and in inoculated fresh fillets of saurel (Trachurus picturatus murphyi) (0.12 kGy) and another Pacific fish species known in Peru as ''lisa'', Mugil cephalus (0.13 kGy), both of which are frequently consumed raw in ''ceviche''. The D_1_0 value was similarly determined in tails of the shrimp species Penaeus vannamei (0.13 kGy). In a second phase of the study, radiation doses in the range 1.0-4.0 kGy were evaluated for use in microbiological shelf-life extension of the selected seafood, and for adverse effects on various sensory attributes (appearance, odor, flavor, and texture). A dose of 1.0 kGy doubled the microbiological shelf-life of fish fillets during post-irradiation storage at 0-1 deg. C to approximately 30 days. This dose was deemed optimal also for preserving all sensory characteristics evaluated except appearance, due to a darkening of fillets. Best ...

Energy Technology Data Exchange (ETDEWEB)

Poly(methyl methacrylate), PMMA, Acrigel, a Brazilian polymer, is used in the manufacture of medical supplies sterilisable by ionizing radiation. However, when PMMA is gamma-irradiated it undergoes main chain scissions, which promote molecular degradation causing reduction in its physical properties. Therefore, radiolytic stabilization of PMMA is important for to become it commercially radio sterilisable. In this work we investigated the radiolytic stabilization of PMMA by using HALS (Hindered Amine Light Stabilizer) additive, commercially used for photo and thermo oxidative stabilization of polymers. The investigation of the radiation-induced main chain scissions was carried out by viscometric method. The additive added to the polymer system at 0.3 % w/w promotes a molecular radioprotection of 61%. That means a reduction of G value (scissions/100 eV) from 2.6 to 1.0. In addition, the glassy transition temperature (Tg) of PMMA (no additive), significantly changed ...

International Nuclear Information System (INIS)

Full text: The general population is daily exposed to chronic, low doses of ionizing radiation (IR) from both natural and artificial sources. The biological consequences of acute, high dose IR exposure can be readily determined; however, the nature and significance of low dose, low dose-rate IR effects are still the subject of debate. Confounding the issue, are the phenomena collectively referred to as the Radiation-induced Bystander Effect (RIBE). The RIBE describes a collection of in vitro observations that suggest the presence of a soluble, transmissible factor(s) released from irradiated cells that can induce a biological response in un-irradiated cells. The induction, nature and magnitude of the RIBE varies between cell culture systems, radiation sources and end-points measured. Efforts to confirm the presence of the RIBE in vivo have been confined to in vivo-like culture systems and limited work with tumour and bone-marrow transplantation models. Validation ...

Science.gov (United States)

Ramsar, a city in the northern Iran, has the highest level of natural background radiation in the world. It has been clearly shown that low doses of ionising radiation can induce resistance to subsequent higher exposures. This phenomenon is termed radioadaptive response. We have compared induction of cytogenetic radioadaptive response by High Natural Background Radiation (HNBR) in Ramsar and X-ray occupational exposure as conditioning doses in human peripheral blood lymphocytes. 30 healthy control individuals, living in Ramsar but in normal background radiation areas, 15 healthy individuals from Talesh Mahalleh, a region with extraordinary high level of background radiation, and 7 X-ray radiographers working in Ramsar hospital located in normal natural background ionising radiation area were evaluated. Peripheral blood samples were prepared and exposed to challenge dose of 0 and 2 Gy. Lymphocytes were scored using analysis of metaphase, for the presence of chromosomal aberrations. An ...

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The radiation-induced microstructural changes have been studied by cross-sectional transmission electron microscopy for single-crystal {alpha}-Al{sub 2}O{sub 3} samples irradiated with triple ion beams (0.25 MeV H{sup +}, 0.6 MeV He{sup +} and 2.4 MeV O{sup 2+}; `Triple (A)`), (0.33 MeV H{sup +}, 0.45 MeV He{sup +} and 1.3 MeV O{sup +}; `Triple (B)`) and three consecutive single ion beams (0.3 MeV H{sup +} ion followed by 0.6 MeV He{sup +} and then 0.8 MeV O{sup +} ions) at 650 C to doses in the range 0.1-8.4 dpa at the damage peak. In the specimen irradiated with Triple (A), having the same average projected range to a total peak dose of 3.7 dpa, cavities with an average diameter of 13 nm were formed between 1.2 and 1.75 {mu}m in depth causing a swelling of 0.1% at the peak, which is larger than those of the specimens irradiated with other conditions. The extent of the cavity-introduced region is some 40% smaller than observed in the damage region due to the ...

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We have observed significant differences in the response to ionizing radiation of two closely related human cell lines, and now compare the effects on these lines of both low and intermediate LET radiation. Compared to TK6, WTK1 has an enhanced X-ray survival, and is also more resistant to cell killing by {alpha}-particles. The hprt locus is more mutable in WTK1 than in TK6 by both X-rays and {alpha}-particles. WTK1 is also more mutable by {alpha}-particles than by X-rays at the hprt locus. X-ray-induced mutation at the heterozygous tk locus in WTK1 is about 25 fold higher than in TK6, while {alpha}-particle-induced mutation is nearly 50 fold higher at this locus. Also, the slowly growing tk- mutants, which comprise the majority of spontaneous and X-ray-induced tk- mutants of TK6, were not induced significantly by {alpha}-particles. Previously, we showed that TK6 has a reduced capacity for recombination compared with WTK1, and therefore, these results indicate that recombinational ...

International Nuclear Information System (INIS)

The purified integral membrane protein, band 3, from human erythrocytes was inserted into egg lecithin liposomes. The insertion of band 3 was determined from thermal transition data from the analysis of the C-H stretching region bands recorded at temperatures from 25 to -22"oC. Raman spectra show that band 3 considerably broadens and lowers the thermal transition of egg lecithin liposomes, suggesting the insertion of band 3. The band 3-inserted liposomes were irradiated with gamma-rays (40 Gy) and the radiation target groups were determined by the analysis of the structural sensitive Raman bands in the 1600-1700 cm"-"1 (amide I), 1200-1300 cm"-"1 (amide III) and 550-1030 cm"-"1 (side chain amino groups) regions. The radiation-sensitive groups as identified from Raman spectra in the region 550-1030 cm"-"1 are tyrosines and cysteines. The radiation-induced changes in the secondary structure were determined from amide I and III bands. Quantitative estimation using the ...

International Nuclear Information System (INIS)

The development of leukemia and thyroid cancer is characterized by activation of the abl oncogene and ret oncogene, respectively. In order to clarify the relationship between these gene aberrations and radiation, the pro-myelogenous leukemia-derived cell line HL60 and the thyroid cancer-derived cell line 8505C, were irradiated in vitro with 100Gy of X-rays. RNA was then extracted from 10"8 cells of the respective cell lines and examined by the reverse transcription PCR method for rearrangements of abl and ret genes. Five kinds of positive bands were observed in the HL-60 cells irradiated with 100Gy of X-ray. Similarly, six positive bands were also observed in the 8505C cells irradiated with 100Gy. In vitro X-irradiation activation of oncogenes found in radiation induced cancers imply that gene rearrangement by X-rays is involved in the development of malignant tumors. Furthermore, in an experiment to detect radiation effects in A-bomb ...

International Nuclear Information System (INIS)

The effects of the antioxidants, vitamin E, propyl gallate, 2-t-butyl-4-methoxy phenol (BHA), 2,6-di-t-butyl-4-methoxy phenol (BHT), nor-dihydroguaiaretic acid (NDGA) and diphenyl-p-phenylene diamine (DPPD) in concentrations ranging between 0.001 per cent and 0.1 per cent have been tested on lipid peroxide formation in synthetic diet mixtures containing herring oil (10 per cent) mixed with starch (90 per cent) irradiated with #gamma#-ray doses of 100 to 2000 krad. On a weight basis NDGA, DPPD, BHA and BHT were most effective and vitamin E and propyl gallate were least effective. An antioxidant concentration of 0.01 per cent normally protected against peroxide formation after a dose of 500 krad but if the dose was increased to 1000 or 2000 krad, much higher doses of antioxidant, up to 0.1 per cent, were required to give protection. Antioxidants prevented peroxide developing during post-irradiation storage even when added after irradiation. Antioxidants were partially or completely ...

International Nuclear Information System (INIS)

We have studied in detail the gamma radiation induced changes in the electrical properties of the (TeO_2)_0_._9 (In_2O_3)_0 _._1 thin films of different thicknesses, prepared by thermal evaporation in vacuum. The current-voltage characteristics for the as-deposited and exposed thin films were analysed to obtain current versus dose plots at different applied voltages. These plots clearly show that the current increases quite linearly with the radiation dose over a wide range and that the range of doses is higher for the thicker films. Beyond certain dose (a quantity dependent on the film thickness), however, the current has been observed to decrease. In order to understand the dose dependence of the current, we analysed the optical absorption spectra for the as-deposited and exposed thin films to obtain the dose dependences of the optical bandgap and energy width of band tails of the localized states. The increase of the current with the gamma ...

Energy Technology Data Exchange (ETDEWEB)

In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. However, exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). Experimental data are presented on the fracture toughness and crack growth rates (CGRs) of wrought and cast austenitic SSs, including weld heat-affected-zone materials, that were irradiated to fluence levels as high as {approx} 2x 10{sup 21} n/cm{sup 2} (E > 1 MeV) ({approx} 3 dpa) in a light water reactor at 288-300 C. The results are compared with the data available in the literature. The effects of material composition, irradiation dose, and water chemistry on CGRs under cyclic and stress corrosion cracking ...

International Nuclear Information System (INIS)

Simulation irradiation experiments were carried out to investigate the formation processes and contribution to hardening of radiation-induced features in low alloy steels. Medium Cu (0.12 and 0.16%) and low Cu (0.03%) A533B steels were irradiated with 3 MeV Ni ions and 5 MeV electrons, and in KUR at 290degC. Irradiated steels were examined by three-dimensional atom probe, positron annihilation, high-resolution transmission electron microscopy and hardness measurements. Electron irradiation caused almost the same hardening as KUR irradiation in medium Cu steels under almost the same dose rate and dose conditions, whereas the formation of larger, denser and more Cu enriched clusters and smaller accumulation of single vacancies were confirmed for KUR irradiation. This indicated that cascade damage provides additional cluster nucleation sites to compensate for lower free point defect production. High dose rate Ni ion irradiation produced Mn-Ni-Si clusters and ...

International Nuclear Information System (INIS)

In this work the diffusion of ion-beam-injected self-interstitials (Is) and their interaction with impurities in crystalline Si are presented. In particular, the I penetration into a molecular beam epitaxy grown Si structure was studied by means of diffusion effects induced on B spikes, analyzed by a developed simulation code. Trapping effects at sample-surface and bulk are evidenced and modeled. The B marker approach was extended to the two-dimensional (2D) I-diffusion occurring as a consequence of ion implantation through a sub-micron dimension patterned oxide mask. I-source size effects on the I penetration have been found and modeled, quantitatively describing the 2D I-diffusion. The I-substitutional carbon interactions have been also studied, showing the C ability to effectively retain Is. The I-trapping mechanism was quantitatively studied by the simulation code, showing that one I is able to deactivate about two C traps by means of I-trapping and C-clustering reactions. This C ...

Energy Technology Data Exchange (ETDEWEB)

Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, transmission electron microscopy measurements of implantation damage were combined with B diffusion experiments using doping marker structures grown by molecular-beam epitaxy (MBE). Damage from nonamorphizing Si implants at doses ranging from 5{times}10{sup 12} to 1{times}10{sup 14}/cm{sup 2} evolves into a distribution of {l_brace}311{r_brace} interstitial agglomerates during the initial annealing stages at 670{endash}815{degree}C. The excess interstitial concentration contained in these defects roughly equals the implanted ion dose, an observation that is corroborated by atomistic Monte Carlo simulations of implantation and annealing processes. The injection of interstitials from the damage region involves the dissolution of {l_brace}311{r_brace} defects during ...

Energy Technology Data Exchange (ETDEWEB)

The rapid growth in the use of in vitro methods for nanoparticle toxicity assessment has proceeded with limited consideration of the unique kinetics of these materials in solution. Particles in general and nanoparticles specifically, diffuse, settle and agglomerate in cell culture media as a function of several systemic and particle factors: media density and viscosity, particle size, shape and density. Cellular dose then is also a function of these factors as they determine the rate of transport of nanoparticles to cells in culture. Here we develop and apply the principles of particokinetics and dosimetry in vitro and outline an approach for simulation of nanoparticle particokinetics in cell culture systems. We illustrate that where equal mass concentrations (?g/ml) imply equal doses for dissimilar materials, the corresponding particle number or surface area concentration doses differ by orders of magnitude. When rates of diffusional and gravitational particle ...

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We studied the interaction of Pu(VI) with Pseudomonas stutzeri ATCC 17588 and Bacillus sphaericus ATCC 14577, representatives of the main aerobic groups of soil bacteria present in the upper soil layers. The accumulation studies have shown that these soil bacteria accumulate high amounts of Pu(VI). The sorption efficiency toward Pu(VI) decreased with increasing biomass concentration due to increased agglomeration of the bacteria resulting in a decreased total surface area and number of available complexing groups. Spores of Bacillus sphaericus showed a higher biosorption than the vegetative cells at low biomass concentration which decreased significantly with increasing biomass concentration. At higher biomass concentrations (> 0.7 g/L), the vegetative cells of both strains and the spores of B. sphaericus showed comparable sorption efficiencies. Investigations on the pH dependency of the biosorption and extraction studies with 0.01 M EDTA solution have shown ...

Energy Technology Data Exchange (ETDEWEB)

The Hyperion project was developed to determine an algorithm for assessing the risk of hydrate plug formation in the pipeline transport oil-water-gas mixtures at low temperatures. The project is a collaboration between physicists, chemists and engineers within the petroleum industry. This paper provided an overview of the project and outlined results obtained as the project entered its third and final year. The main objective of the project has been to understand the inherent mitigation effects of some oils on gas hydrate formation as well as to develop methods of predicting the risk of hydrate plugging. To date, the project has extracted and studied natural inhibiting components (NICs) in oils. Molecular modelling techniques have been used to study hydrate and fluid interfaces in order to estimate the driving force of agglomeration and growth through mechanical surface stress and measurement of surface wave fluctuations. A scheme is also being developed measure ...

Energy Technology Data Exchange (ETDEWEB)

This project is sponsored by the United States Department of Energy (DOE) for the ``Engineering Design and Analysis of Advanced Physical Fine Coal Cleaning Technologies: The major goal is to provide the simulation tools for modeling both conventional and advanced coal cleaning technologies. This DOE project is part of a major research initiative by the Pittsburgh Energy Technology Center (PETC) aimed at advancing three advanced coal cleaning technologies-heavy-liquid cycloning, selective agglomeration, and advanced froth flotation through the proof-of-concept (POC) level. The commercially available ASPEN PLUS process simulation package will be extended to handle coal cleaning applications. Algorithms for predicting the process performance, equipment size, and flowsheet economics of commercial coal cleaning devices and related ancillary equipment will be incorporated into the coal cleaning simulator. This report is submitted to document the progress of Aspen ...

Energy Technology Data Exchange (ETDEWEB)

High-spatial-resolution microfocus-based X-ray imaging technology, both real-time and film, has been used to study the thickness variation that occurs in the oxide core of silver-sheathed BSCCO ribbons produced by the powder-in-tube method. This thickness variation (also called ``sausaging``) occurs during incremental rolling and degrades the critical current densities of the ribbons. Using X-ray image data the authors determined the onset and severity of sausaging. Onset occurred at a ribbon thickness of 203 {micro}m, and the severity increased with subsequent rolling reductions. Scanning electron microscopy was used to confirm the X-ray image data. X-ray imaging provides several advantages over more traditional methods for characterizing the superconductors such as optical or scanning electron microscopy. The X-ray imaging provides nondestructive information about the entire width of the ribbon, with far greater speed, lower cost, and more flexibility than the ...

International Nuclear Information System (INIS)

Uranium-aluminum alloys with a significant enrichment of uranium with "2"3"3U or "2"3"5U serve as nuclear fuels in research reactors. The quality assurance of this fuel requires, among other things, precise knowledge that all trace metal constituents that affect neutron economy, fuel integrity, and fuel fabrication process parameters are well within the specification limits. Trace metal characterization of "2"3"5U-Al alloy has been carried out by atomic spectrometry. The trace metal constituents of interest are grouped into common metals (silver, boron, calcium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, sodium, nickel, lead, silicon, tin, titanium, vanadium, tungsten, and zinc) and lanthanides (cerium, dysprosium, europium, gadolinium, holminium, lutetium, samarium, and terbium). The elements yttrium and zirconium are grouped with the latter in view of the chemical separation procedure used. The alloy samples are dissolved in 6 M ...

International Nuclear Information System (INIS)

To clarify the effects of the principal factors that govern the thermal fragmentation of a molten metallic fuel jet in the course of fuel-coolant interaction, which is important in evaluating the sequence of core disruptive accidents (CDAs) for metallic fuel fast reactors, basic experiments were carried out using molten metallic fuel simulants (copper and silver) and a sodium pool.Fragmentation of a molten metal jet with a solid crust was caused by internal pressure produced by the boiling of sodium, which is locally entrapped inside the jet due to hydrodynamic motion between the jet and the coolant. The superheating and the latent heat of fusion of the jet are the principal factors governing this type of thermal fragmentation. On the other hand, the effect of the initial sodium temperature is regarded as negligible in the case of thermal conditions expected to result in CDAs for practical metallic fuel cores. Based on the fragmentation data for several kinds of ...

Energy Technology Data Exchange (ETDEWEB)

Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence may be useful for ...

British Library Electronic Table of Contents (United Kingdom)

Abstract The aim of this paper was to examine the result of rotary root canal preparation with the nickel-titanium (NiTi) systems K3, ProTaper and Mtwo. One hundred and fifty curved artificial root canals and 60 mesial canals of human mandibular molars were selected. In the group of curved artificial canals, all canals were prepared to size 35/0.04 taper with the three systems. In the group of human mandibular molars, the teeth with mature root canals were radiographed with silver points inserted in bucco-lingual and in mesio-distal positions. In the artificial root group, one K3 instrument separated. Mtwo (20%) showed significantly (P = 0.003) less zips than K3 (46.9%) or ProTaper (50%). There were no significant differences in ledge and elbow formation. K3 and Mtwo had the lowest percent...

British Library Electronic Table of Contents (United Kingdom)

A novel visible light sensitive photocatalyst, AgSbO3 was prepared by a conventional solid-state reaction method. This oxide belonging to a cubic-pyrochlore structure can absorb visible light with wavelength up to about 480nm. From the band structure calculation, we found that the top of the valence band consists of the hybridized Ag 4d and O 2p orbitals and the bottom of the conduction band mainly consists of the Ag 5s and the Sb 5s orbitals. Photocatalytic activities were evaluated using O2 evolution from an aqueous silver nitrate solution and decomposition of gaseous 2-propanol under visible light irradiation. We found that AgSbO3 shows a higher O2 evolution activity than WO3 and 2-propanol can be mineralized by the AgSbO3 photocatalysis under visible light irradiation.

Energy Technology Data Exchange (ETDEWEB)

More than 100 old mine dumps active mine tailing ponds and granite quarries were investigated in South-West Germany to evaluate their potential impact on the environment caused by natural radioactive materials and by toxic metals. Five mine sites were monitored for a longer period according to their radon impact on the environment. They showed seasonal variations greater than a factor of 5 at some places. The annual mean radon concentration over granitic soil was found to be about 44 Bq.m/sup -3/ while very near the dumps more than 370 Bq.m/sup -3/ were usual. Radium concentrations up to 185 Bq.kg/sup -1/ were found in certain types of abandoned mine dumps. Some of the waste rock piles investigated are in the immediate neighbourhood of buildings and some old mine establishments are now used as homes. In these dwellings passive time integrating radon dosemeters have been exposed for up to a three month period. The average radon concentrations in the buildings influenced by mining ranged ...

Energy Technology Data Exchange (ETDEWEB)

This poster presentation dealt with a brief overview of the practices in effect in British Columbia related to metal leaching and acid mine drainage. The metals mined in the province include coal, gold, silver, copper, molybdenum, lead, and zinc. Some mines operate under the surface, while others are strip mines, etc. under a variety of climactic conditions and a host of different mining companies, such as Cominco, Placer Dome and Noranda. The primary objective is the prevention of negative environmental impacts on land and in the water. Salmon and other fish need to be protected. A secondary objective is the minimization of impacts on the biota, which requires a detailed study of ecological risks. The solution often lies in soil covering. To illustrate, the author described the situation at Huckleberry Mines Ltd. and the remedial action that was implemented, and discussed the results on the beavers. In conclusion, the author discussed the strategies implemented by ...

Energy Technology Data Exchange (ETDEWEB)

High-quality solar cells have been fabricated by utilizing localized argon-ion laser decomposition of silver neodecanoate spun onto diffused silicon substrates and subsequent electroplating. Early adhesion problems during electroplating have been carefully studied and finally solved using a novel coating procedure. The laser-metallized solar cells have been characterized using lighted and dark current-voltage measurements and compared with baseline cells metallized using standard photolithographic procedures. Non-AR-coated cell efficiencies ranging from 10 to over 11% have been obtained for the laser-metallized cells, comparable with the best baseline cells. The laser-metallized cells have 30 to 40% lower series resistance than the unsintered baseline cells, indicating that in-situ sintering takes place during laser writing. A dramatic new and simpler laser metallization process on which patent protection is currently being sought has yielded non-AR-coated cell ...

International Nuclear Information System (INIS)

The first-order relativistic correction to the kinetic energy of an electron, the mass-velocity term, is not bounded from below. It can, therefore, not be used within a variational framework. To overcome this deficiency we developed a method to include the entire relativistic kinetic energy #sq root#(p"2c"2+m_0"2c"4)-m_0c"2 in a spline-augmented plane-wave band calculation. The first results for silver are quite promising, especially for d and p states: The analysis of the energies of the core states as well as of the valence band structure suggests that the energies of d bands are reproduced within 1 mRy. However, the combination of the relativistic kinetic energy with the Darwin term leads to energies which are too low for s-like valence states by 10 mRy. Therefore, the s and d valence band complex is spread out and the Fermi level is lowered by the same amount as the s states. We expect to overcome these deficiencies in future investigations by using a ...

International Nuclear Information System (INIS)

The dosimetric characteristics for a new brachytherapy seed source (I-Plant"T"M model 3600) were measured using LiF thermoluminescent dosimeters and appropriate phantom materials in conformance with the methodology and guidance provided by the AAPM Task Group 43. The I-Plant"T"M model 3600 is the successor to the I-Plant"T"M model 3500. The major difference between these sources is that the model 3600 contains a leaded-glass core to provide radio-opacity (while the model 3500 contains a silver core), which does not produce spectral contamination upon neutron activation. The dose rate constant #LAMBDA# for the model 3600 was determined to be 1.00 Gy h"-"1 U"-"1 (with a 6% overall relative standard deviation), compared to 1.01 cGy h"-"1 U"-"1 reported for the model 3500 in previous studies. The remaining dosimetric characteristics also are similar for both sources.

International Nuclear Information System (INIS)

We have studied the efficiency of ozone production by pulsed positive corona discharge in coaxial wire-cylinder geometry at atmospheric pressure. A corona discharge was generated by short (#approx#150 ns) high voltage pulses applied between a silver coated copper wire anode and stainless steel cylinder cathode in synthetic air. A pyrex probe and Teflon tube was used for collecting discharge products and an ozone concentration was monitored outside of the discharge chamber by a non-dispersive UV absorption technique. The production of ozone was investigated as a function of energy density (10"-"4-3x10"-"1 Wh l"-"1) delivered to the discharge volume by combining the discharge frequency (0.1-10 Hz) and airflow rate (1-32 l min"-"1). From ozone concentration measurements we have evaluated the ozone production, yield and production energy cost. The ozone production yield and cost vary in the range of 15-55 g kWh"-"1 and 35-110 eV/molecule. (author)

Energy Technology Data Exchange (ETDEWEB)

W have introduced template-synthesized metal phosphate nanoparticle labels for electrochemical immunoassay. Such use of an apoferritin template offers a simple and convenient route to prepare metallic nanoparticle labels for electrochemical immunoassays and avoid the complicated and time-consuming nanoparticle synthesis process (QD synthesis). Releasing metal ions from metal phosphate in an acetate buffer (pH 4.6) eliminates the harsh condition in the traditional metallic nanoparticle dissolution (e.g., strong acid dissolution of QDs and gold nanoparticles). This method is ultrasensitive and its DL is low to 77fM. The simultaneous detection of multiple protein targets is easily performed by using different metal phosphate nanoparticle labels (cadmium phosphate and lead phosphate). This approach can be extended to prepare multiple metal (such as zinc, lead, cadmium, copper, indium, gold, silver) phosphate nanoparticle labels or hybrid metal (bimetallic or ...

International Nuclear Information System (INIS)

Background and purpose: The low density of lung tissue causes a reduced attenuation of photons and an increased range of secondary electrons, which is inaccurately predicted by the algorithms incorporated in some commonly available treatment planning systems (TPSs). This study evaluates the differences in dose in normal lung tissue computed using a simple and a more correct algorithm. We also studied the consequences of these differences on the dose-effect relations for radiation-induced lung injury. Materials and methods: The treatment plans of 68 lung cancer patients initially produced in a TPS using a calculation model that incorporates the equivalent-pathlength (EPL) inhomogeneity-correction algorithm, were recalculated in a TPS with the convolution-superposition (CS) algorithm. The higher accuracy of the CS algorithm is well-established. Dose distributions in lung were compared using isodoses, dose-volume histograms (DVHs), the mean lung dose (MLD) and the ...

Science.gov (United States)

The three mammalian transforming growth factor (TGF)-? isoforms (TGF-?1, TGF-?2, and TGF-?3) differ in their putative roles in radiation-induced fibrosis in intestine and other organs. Furthermore, tissue specificity of TGF-? action may result from temporal or spatial changes in production and/or activation. The present study examined shifts in the cell types expressing TGF-? mRNA relative to TGF-? immunoreactivity and histopathological injury during radiation enteropathy development. A 4-cm loop of rat small intestine was locally exposed to 0, 12, or 21-Gy single doses of x-irradiation. Sham-irradiated and irradiated intestine were procured 2 and 26 weeks after irradiation. Cells expressing the TGF-?1, TGF-?2, or TGF-?3 transcripts were identified by in situ hybridization with digoxigenin-labeled riboprobes. Intestinal wall TGF-? immunoreactivity was measured using computerized image analysis, and structural radiation injury was assessed by quantitative ...

Energy Technology Data Exchange (ETDEWEB)

The primary objective of this task was to perform a variability study of the high activity waste (HAW) acidic feed to determine the impact of feed variability on the quality of the final grout and on the mixability of the salt solution into the dry powders. The HAW acidic feeds were processed through the neutralization/pH process, targeting a final pH of 12. These fluids were then blended with the dry materials to make the final waste forms. A secondary objective was to determine if elemental substitution for cost prohibitive or toxic elements in the simulant affects the mixing response, thus providing a more economical simulant for use in full scale tests. Though not an objective, the HAW simulant used in the full scale tests was also tested and compared to the results from this task. A statistically designed test matrix was developed based on the maximum molarity inputs used to make the acidic solutions. The maximum molarity inputs were: 7.39 HNO{sub 3}, 0.11618 gallium, 0.5423 ...