In this process, used oxide nuclear fuel is treated with fluorine gas to form a mixture of fluorides. This mixture is then distilled to separate the different classes of material. Uranium enrichment produces large quantities of depleted uranium hexafluoride, or DUF 6 , as a waste product. The long-term storage of DUF 6 presents environmental, health, and safety risks because of its chemical instability. When UF 6 is exposed to moist air, it reacts with the water in the air to produce UO 2 F 2 uranyl fluoride and HF hydrogen fluoride both of which are highly corrosive and toxic.
The estimated lifetime of the steel cylinders is measured in decades. There have been several accidents involving uranium hexafluoride in the US, including a cylinder-filling accident and material release at the Sequoyah Fuels Corporation in Ruptured ton UF 6 shipping cylinder.
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Uranium hexafluoride Uranium VI fluoride. CAS Number. Interactive image. PubChem CID. Chemical formula. Solubility in water. Soluble in chloroform , CCl 4 , liquid chlorine , and bromine Dissolves in nitrobenzene. Crystal structure. Space group. Coordination geometry. Dipole moment. Std molar entropy S o Archived from the original on Retrieved The Journal of Chemical Thermodynamics.
Levy; John C. Taylor; Paul W. Wilson Part XII. Levy, J. Taylor and A. Waugh Journal of Fluorine Chemistry. Taylor, P. Wilson, J. Deviations from ideal symmetry in the structure of crystalline UF 6 : a neutron diffraction analysis", Acta Crystallogr. Olah; J.
Welch Oxidation of organic compounds with uranium hexafluoride in haloalkane solutions". Berry; R. Poole; A. Prescott; D. Sharp; J. Winfield Walker; P. Halasyamani; S. Allen; D. O'Hare USEC Inc. Argonne National Laboratory. Is it dangerous and what should we do with it? Institute for Energy and Environmental Research. Large and Associates.
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The attenuation of vacuum ultraviolet VUV radiation by helium at pressures up to 20 atm over path lengths of about 61 cm and in the approximate wavelength range between 80 and nm was studied. Finally, an investigation was initiated to provide basic spectral emission and absorption data for UF6 and possible thermal decomposition products of UF6 at elevated temperatures.
Electron beam control for barely separated beams. A method for achieving independent control of multiple beams in close proximity to one another, such as in a multi-pass accelerator where coaxial beams are at different energies, but moving on a common axis, and need to be split into spatially separated beams for efficient recirculation transport. The method for independent control includes placing a magnet arrangement in the path of the barely separated beams with the magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole.
The magnetic fields are then tuned to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets. The magnetic fields may be tuned to cancel out either the dipole component or tuned to cancel out the quadrupole component in order to independently control the separate beams. Water Accommodation on Bare and Coated Ice. A good understanding of water accommodation on ice surfaces is essential for quantitatively predicting the evolution of clouds, and therefore influences the effectiveness of climate models.
However, the accommodation coefficient is poorly constrained within the literature where reported values vary by up to three orders of magnitude. In addition, the complexity of the chemical composition of the atmosphere plays an important role in ice phase behavior and dynamics. We employ an environmental molecular beam EMB technique to investigate molecular water interactions with bare and impurity coated ice at temperatures from K to K. In this work, we summarize results of water accommodation experiments on bare ice Kong et al. Hexanol is chosen as a complementary chain alcohol to methanol and butanol, while nitric acid is a common inorganic compound in the atmosphere.
The results show a strong negative temperature dependence of water accommodation on bare ice, which can be quantitatively described by a precursor model. Acidic adlayers tend to enhance water uptake indicating that the system kinetics are thoroughly changed compared to bare ice. Adsorbed alcohols influence the temperature dependence of the accommodation coefficient and water molecules generally spend less time on the surfaces before desorbing, although the measured accommodation coefficients remain high and comparable to bare ice for the investigated systems.
We conclude that impurities can either enhance or restrict water uptake in ways that are influenced by several factors including temperature and type of adsorbant, with potential implications for the description of ice particle growth in the atmosphere. This work was supported by the Swedish Research Council and. Trolley wires and bare power conductors shall be guarded at The potential on bare signal wires accessible to contact Model calculations using estimated reaction rates of sulfur hexafluoride SF6 with OH and 0 'D indicate that the atmospheric lifetime due to these processes may be very long 25, years.
An upper limit for the UV cross section would suggest a photolysis lifetime much longer than years. The possibility of other removal mechanisms are discussed. The estimated lifetimes are consistent with other estimated values based on recent laboratory measurements. There appears to be no known natural source of SF6. Based on historical emission rates, we calculated a present-day atmospheric concentrations for SF6 of about 2.
It is difficult to estimate the atmospheric lifetime of SF6 based on mass balance of the emission rate and observed abundance. There are large uncertainties concerning what portion of the SF6 is released to the atmosphere. Even if the emission rate were precisely known, it would be difficult to distinguish among lifetimes longer than years since the current abundance of SF6 is due to emission in the past three decades. More information on the measured trends over the past decade and observed vertical and latitudinal distributions of SF6 in the lower stratosphere will help to narrow the uncertainty in the lifetime.
Based on laboratory-measured IR absorption cross section for SF6, we showed that SF6 is about 3 times more effective as a greenhouse gas compared to CFC 11 on a per molecule basis. However, its effect on atmospheric warming will be minimal because of its very small concentration. We estimated the future concentration of SF6 at to be 8 and 10 pptv based on two projected emission scenarios.
The corresponding equilibrium warming of 0. As an odorless, non-toxic, and inert compound, sulfur hexafluoride SF6 is one of the most widely used tracer gases in indoor air quality studies in both controlled and uncontrolled environments. This compound may be subject to hydrolysis under elevated temperature to form acidi Method for monitoring stack gases for uranium activity.
A method for monitoring the stack gases of a purge cascade of gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride , if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases.
A method for monitoring the stack gases of a purge cascade of a gaseous diffusion plant for uranium activity. Do Bare Rocks Exist on the Moon? Astronaut surface observations and close-up images at the Apollo and Chang'e 1 landing sites confirm that at least some lunar rocks have no discernable dust cover. Over millions of years such dust might be expected to coat all exposed rock surfaces.
This study uses thermal modeling, combined with Diviner a Lunar Reconnaissance Orbiter experiment orbital lunar eclipse temperature data, to further document the existence of bare rocks on the lunar surface. High-voltage electrical apparatus utilizing an insulating gas of sulfur hexafluoride and helium.
High-voltage electrical apparatus includes an outer housing at low potential, an inner electrode disposed within the outer housing at high potential with respect thereto, and support means for insulatably supporting the inner electrode within the outer housing. Conducting particles contaminate the interior of the outer housing, and an insulating gas electrically insulates the inner electrode from the outer housing even in the presence of the conducting particles.
The insulating gas is comprised of sulfur hexafluoride at a partial pressure of from about 2. The sulfur hexafluoride comprises between 20 and 65 volume percent of the insulating gas. Measuring herbicide volatilization from bare soil. A field experiment was conducted to measure surface dissipation and volatilization of the herbicide triallate after application to bare soil using micrometeorological, chamber, and soil-loss methods. The volatilization rate was measured continuously for 6.
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Soil samples were taken within 30 min after application and the measured mass of triallate was 8. The measured triallate mass in the soil at the end of the experiment was approximately 6 kg ha The triallate dissipation rate, obtained by soil sampling, was approximately g ha -1 d -1 98 g d -1 and the average rate of volatilization was g ha -1 d Significant volatilization of triallate is possible when applied directly to the soil surface without incorporation. Laboratory-scale uranium RF plasma confinement experiments. An experimental investigation was conducted using 80 kW and 1.
Pure uranium hexafluoride UF6 was injected into argon-confined, steady-state, RF-heated plasmas in different uranium plasma confinement tests to investigate the characteristics of plamas core nuclear reactors. The objectives were: 1 to confine as high a density of uranium vapor as possible within the plasma while simultaneously minimizing the uranium compound wall deposition; 2 to develop and test materials and handling techniques suitable for use with high-temperature, high-pressure gaseous UF6; and 3 to develop complementary diagnostic instrumentation and measurement techniques to characterize the uranium plasma and residue deposited on the test chamber components.
In all tests, the plasma was a fluid-mechanically-confined vortex-type contained within a fused-silica cylindrical test chamber. The test chamber peripheral wall was 5. Role of water in the tribochemical removal of bare silicon. Experimental results revealed that the water played an important role in the tribochemical wear of the bare silicon.
A hillock-like wear trace with a height of 0. As the RH increased, the wear depth increased and reached the maximum level in water. Analysis of frictional dissipated energy suggested that the wear of the bare silicon was not dominated by mechanical interactions. High-resolution transmission electron microscopy detection demonstrated that the silicon atoms and crystal lattice underneath the worn area maintained integral perfectly and thus further confirmed the tribochemical wear mechanism of the bare silicon.
Finally, the role of water in the tribochemical wear of the bare silicon may be explained by the following three aspects: the hydroxylation by hydroxyl ions auto-ionized in water, the hydrolytic reaction of water molecules, and the dissolution of the tribochemical product SiOmHn in liquid water. The results of this paper may provide further insight into the tribochemical removal mechanism of bare monocrystalline silicon and furnish the wider reaction cognition for chemical mechanical polishing. Electromagnetic signals from bare strange stars.
The crystalline color superconducting phase is believed to be the ground state of deconfined quark matter for sufficiently large values of the strange quark mass. This phase has the remarkable property of being more rigid than any known material. It can therefore sustain large shear stresses, supporting torsional oscillations of large amplitude. The torsional oscillations could lead to observable electromagnetic signals if strange stars have a crystalline color superconducting crust.
Indeed, considering a simple model of a strange star with a bare quark matter surface, it turns out that a positive charge is localized in a narrow shell about ten Fermi thick beneath the star surface. The electrons needed to neutralize the positive charge of quarks spill in the star exterior forming an electromagnetically bounded atmosphere hundreds of Fermi thick. When a torsional oscillation is excited, for example by a stellar glitch, the positive charge oscillates with typical kHz frequencies, for a crust thickness of about one-tenth of the stellar radius, to hundreds of Hz, for a crust thickness of about nine-tenths of the stellar radius.
Higher frequencies, of the order of few GHz, can be reached if the star crust is of the order of a few centimeters thick. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. The radiated photons will be in part absorbed by the electronic atmosphere, but a sizable fraction of them should be emitted by the star. This patent relates to high purity uranium alloys characterized by improved stability to thermal cycling and low thermal neutron absorption.
The high purity uranium alloy contains less than 0. American elevator looking east barely visible behind American malt American elevator looking east barely visible behind American malt house with Russell-Miller flour mill to right now Eonacara and idle. Radiative transfer model of snow for bare ice regions. Modeling a radiative transfer RT for coupled atmosphere-snow- bare ice systems is of fundamental importance for remote sensing applications to monitor snow and bare ice regions in the Greenland ice sheet and for accurate climate change predictions by regional and global climate models.
Recently, the RT model for atmosphere-snow system was implemented for our regional and global climate models. However, the bare ice region where recently it has been expanded on the Greenland ice sheet due to the global warming, has not been implemented for these models, implying that this region leads miscalculations in these climate models. Thus, the RT model of snow for bare ice regions is needed for accurate climate change predictions. We developed the RT model for coupled atmosphere-snow- bare ice systems, and conducted a sensitivity analysis of the RT model to know the effect of snow, bare ice and geometry parameters on the spectral radiant quantities.
The RT model considers snow and bare -ice inherent optical properties IOPs , including snow grain size, air bubble size and its concentration and bare ice thickness. The conventional light scattering theory, Mie theory, was used for IOP calculations. Monte Carlo method was used for the multiple scattering. The sensitivity analyses showed that spectral albedo for the bare ice increased with increasing the concentration of the air bubble in the bare ice for visible wavelengths because the air bubble is scatterer with no absorption.
For near infrared wavelengths, spectral albedo has no dependence on the air bubble due to the strong light absorption by ice. When increasing solar zenith angle, the spectral albedo were increased for all wavelengths. This is the similar trend with spectral snow albedo. Cloud cover influenced the bare ice spectral albedo by covering direct radiation into diffuse radiation.
Converting direct into diffuse radiation reduces the. Measurement of cardiac output using improved chromatographic analysis of sulfur hexafluoride SF6. A constant current variable frequency pulsed electron capture detector has been incorporated into the gas chromatographic analysis of trace amounts of sulfur hexafluoride SF6 in water and blood. The resulting system offers a broader effective operating range than more conventional electron capture units and has been utilized for measurements of cardiac output employing constant-rate infusion of dissolved SF6.
The SF6 technique has been validated against direct volumetric measurements of cardiac output in a canine right-heart bypass preparation and used subsequently for rapidly repeated measurements in conscious animals and man. High temperature UF6 RF plasma experiments applicable to uranium plasma core reactors. An investigation was conducted using a 1. Pure, high temperature uranium hexafluoride UF6 was injected into an argon fluid mechanically confined, steady state, RF heated plasma while employing different exhaust systems and diagnostic techniques to simulate and investigate some potential characteristics of uranium plasma core nuclear reactors.
The development of techniques and equipment for fluid mechanical confinement of RF heated uranium plasmas with a high density of uranium vapor within the plasma, while simultaneously minimizing deposition of uranium and uranium compounds on the test chamber peripheral wall, endwall surfaces, and primary exhaust ducts, is discussed. The material tests and handling techniques suitable for use with high temperature, high pressure, gaseous UF6 are described and the development of complementary diagnostic instrumentation and measurement techniques to characterize the uranium plasma, effluent exhaust gases, and residue deposited on the test chamber and exhaust system components is reported.
The bonding to uranium of sheathing of iron or cobalt, or nickel, or alloys thereof is described. The bonding is accomplished by electro-depositing both surfaces to be joined with a coating of silver and amalgamating or alloying the silver layer with mercury or indium. Then the silver alloy is homogenized by exerting pressure on an assembly of the uranium core and the metal jacket, reducing the area of assembly and heating the assembly to homogenize by diffusion. PubMed Central. A poly-row branched spike prbs barley mutant was obtained from soaking a two-rowed barley inflorescence in a solution of maize genomic DNA.
It is still unknown whether the interaction of retrotransposons between barley and maize has resulted in the recombination observed in the present study. Plasma chemical conversion of sulphur hexafluoride initiated by a pulsed electron beam. This paper presents the results of the experimental investigation of plasma chemical conversion of sulphur hexafluoride initiated by a pulsed electron beam TEA pulsed electron accelerator with the following characteristics: keV electron energy, 60 ns pulse duration, up to J pulse energy, and 5 cm beam diameter.
For the mixture of SF6 and oxygen, the results indicated chemical reactions involving the formation of a number of products of which one is sulphur, confirming the Wray - Fluorescence Analysis. The plasma chemical conversion of SF6 initiated by the pulsed electron beam was not detected when SF6 was mixed with Ar or N2, suggesting a possible mechanism for the reaction of SF6 in the presence of O2. Gas exchange-wind speed relation measured with sulfur hexafluoride on a lake. Gas-exchange processes control the uptake and release of various gases in natural systems such as oceans, rivers, and lakes.
Not much is known about the effect of wind speed on gas exchange in such systems. In the experiment described here, sulfur hexafluoride was dissolved in lake water, and the rate of escape of the gas with wind speed at wind speeds up to 6 meters per second was determined over a 1-month period. A sharp change in the wind speed dependence of the gas-exchange coefficient was found at wind speeds of about 2. However the gas-exchange coefficients at wind speeds above 3 meters per second were smaller than those observed in wind tunnels and are in agreement with earlier lake and ocean results.
A sulfur hexafluoride sensor using quantum cascade and CO2 laser-based photoacoustic spectroscopy. The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas sensors has been the subject of several research programs.
An important greenhouse gas is sulphur hexafluoride , an almost non-reactive gas widely employed in industrial processes worldwide. Indeed it is estimated that it has a radiative forcing of 0. This work compares two photoacoustic spectrometers, one coupled to a CO 2 laser and another one coupled to a Quantum Cascade QC laser, for the detection of SF 6.
The laser photoacoustic spectrometers described in this work have been developed for gas detection at small concentrations. Detection limits of 20 ppbv for CO 2 laser and 50 ppbv for quantum cascade laser were obtained. Genetics Home Reference: bare lymphocyte syndrome type II. The RFX complex is crucial Bare lymphocyte syndrome: an opportunity to discover our immune system. Immunol Lett. The purpose of this research was to determine the feasibility of developing a microcomputer based management information system MIS Keyword: Management information system , Bare bases, Civil engineering, Data bases, Information retrieval.
Uranium , natural. Uranium alloys containing from 0. Attention is currently being given to methods that assess the ecological condition of rangelands throughout the United States. There are a number of different indicators that assess ecological condition of rangelands.
Bare Ground is being considered by a number of agencies and resource specialists as a lead indicator that can be evaluated over a broad area. Traditional methods of measuring bare ground rely on field technicians collecting data along a line transect or from a plot. In this study, both fixed wing and helicopter UAVs were used to measure bare ground in a sagebrush steppe ecosystem. The data were collected with digital imagery and read using the image analysis software SamplePoint. The approach was tested over seven different plots and compared against traditional field methods to evaluate accuracy for assessing bare ground.
The field plots were located on the Idaho National Laboratory INL site west of Idaho Falls, Idaho in locations where there is very little disturbance by humans and the area is grazed only by wildlife. The comparison of fixed-wing and helicopter UAV technology against field estimates shows good agreement for the measurement of bare ground. This study shows that if a high degree of detail and data accuracy is desired, then a helicopter UAV may be a good platform.
If the data collection objective is to assess broad-scale landscape level changes, then the collection of imagery with a fixed-wing system is probably more appropriate. The term uranium feed or natural uranium feed means natural uranium in the form of UF6 suitable for uranium The behavior of symmetrical coupled-core systems has been extensively studied, yet there is a dearth of research on asymmetrical systems due to the increased complexity of the analysis of such systems.
In this research, the multipoint kinetics method is applied to asymmetrical zeropower, subcritical, bare metal reactor systems. Existing research on asymmetrical reactor systems assumes symmetry in the neutronic coupling; however, it will be shown that this cannot always be assumed.
Deep subcriticality adds another layer of complexity and requires modification of the multipoint kinetics equations to account for the effect of the external neutron source. Subsequently, the Rossi-alpha equations are derived for a two-region asymmetrical reactor system. The predictive capabilities of the radiation transport code MCNP6 for neutron noise experiments are shown in a comparison to the results of a series of Rossi-alpha measurements performed by J. Mihalczo utilizing a coupled set of symmetrical bare highly-enriched uranium HEU cylinders. The ptrac option within MCNP6 can generate time-tagged counts in a cell list-mode data.
The list-mode data can then be processed similarly to measured data to obtain values for system parameters such as the dual prompt neutron decay constants observable in a coupled system. The results from the ptrac simulations agree well with the historical measured values. A series of case studies are conducted to study the effects of geometrical asymmetry in the coupling between two bare metal HEU cylinders.
While the coupling behavior of symmetrical systems has been reported on extensively, that of asymmetrical systems remains sparse. In particular, it appears that there has been no previous research in obtaining the coupling time constants for asymmetrically-coupled systems. The difficulty in observing such systems is due in part to the inability to determine the.
Radar reflectivity of bare and vegetation-covered soil. Radar sensitivity to soil moisture content has been investigated experimentally for bare and vegetation-covered soil using detailed spectral measurements obtained by a truck-mounted radar spectrometer in the GHz band and by airborne scatterometer observations at 1. It is shown that radar can provide quantitative information on the soil moisture content of both bare and vegetation-covered soil. The observed soil moisture is in the form of the soil matric potential or a related quantity such as the percent of field capacity.
The depth of the monitored layer varies from 1 cm for very wet soil to about 15 cm for very dry soil. Analysis of the XRR yields the electron density profile across the charged-interfaces along the surface normal showing the AuNPs assemble with vertical thickness comparable to the particle size.
Efficient removal of sulfur hexafluoride SF6 through reacting with recycled electroplating sludge. This paper reports that recycled electroplating sludge is able to efficiently remove greenhouse gas sulfur hexafluoride SF6. The removal process involves various reactions of SF6 with the recycled sludge. Remarkably, the sludge completely removed SF6 at a capacity of 1.
These generated gases can be readily captured and removed by NaOH solution. The reacted solids were further found to be various metal fluorides, thus revealing that SF6 removal takes place by reacting with various metal oxides and silicate in the sludge. Moreover, the kinetic investigation revealed that the SF6 reaction with the sludge is a first-order chemically controlled process.
This research thus demonstrates that the waste electroplating sludge can be potentially used as an effective removal agent for one of the notorious greenhouse gases, SF6. Abatement of sulfur hexafluoride emissions from the semiconductor manufacturing process by atmospheric-pressure plasmas. Sulfur hexafluoride SF6 is an important gas for plasma etching processes in the semiconductor industry. SF6 intensely absorbs infrared radiation and, consequently, aggravates global warming.
This study investigates SF6 abatement by nonthermal plasma technologies under atmospheric pressure. Two kinds of nonthermal plasma processes--dielectric barrier discharge DBD and combined plasma catalysis CPC --were employed and evaluated. However, poisoning of catalysts by sulfur S -containing species needs further investigation.
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They do not cause global warming and can be captured by either wet scrubbing or adsorption. The variability of methane, nitrous oxide and sulfur hexafluoride in Northeast India. Ganesan, A. The observations show large variability and frequent pollution events in CH4 and N2O mole fractions, suggesting significant sources in the regions sampled by Darjeeling throughout the year.
In contrast, SF6 mole fractions show little variability and only occasional pollution episodes, likely due to weak sources in the region. Simulations using the Numerical Atmospheric dispersion Modelling Environment NAME particle dispersion model suggest that many of the enhancements in the three gases result from the transport of pollutants from the densely populated Indo-Gangetic plains of India to Darjeeling.
The meteorology of the region varies considerably throughout the year from Himalayan flows in the winter to the strong South Asian summer monsoon. By contrast, SF6 mole fractions show little variability and only occasional pollution episodes, likely due to weak sources in the region. Simulations using the Numerical Atmospheric dispersion Modelling Environment NAME particle dispersion model suggest that many of the enhancements in the three gases result from the transport of pollutants from the densely populated Indo-Gangetic Plains of India to Darjeeling.
The meteorology of the region varies considerably throughout the year from Himalayan flows in the winter to the strong south Asian summer monsoon. Six electrical workers accidentally exposed to degradation products of sulphur hexafluoride SF6 during electrical repair work were followed up for one year. One degradation product, sulphur tetrafluoride SF4 , was identified from worksite measurements. Unprotected exposure in an underground enclosed space occurred for six hours over a 12 hour period. Initial symptoms included shortness of breath, chest tightness, productive cough, nose and eye irritation, headache, fatigue, nausea, and vomiting.
Symptoms subsided when exposure was interrupted during attempts to identify the cause of the problem. Although exposure ended after several hours, four workers remained symptomatic for between one week and one month. Pulmonary radiographic abnormalities included several discrete areas of transitory platelike atelectasis in one worker, and a slight diffuse infiltrate in the left lower lobe of another. One worker showed transient obstructive changes in tests of pulmonary function. Examination at follow up after one year showed no persistent abnormalities.
Preliminary data from this paper were presented at the VIIth international pneumoconioses conference. Pittsburgh, PA, August Numerical study to assess sulfur hexafluoride as a medium for testing multielement airfoils. A methodology is described for computing viscous flows of air and sulfur hexafluoride SF6. The basis is an existing flow solver that calculates turbulent flows in two dimensions on unstructured triangular meshes.
The solver has been modified to incorporate the thermodynamic model for SF6 and used to calculate the viscous flow over two multielement airfoils that have been tested in a wind tunnel with air as the test medium. Flows of both air and SF6 at a free-stream Mach number of 0. The computations are used to investigate the suitability of SF6 as a test medium in wind tunnels and are a follow-on to previous computations for single-element airfoils. Surface-pressure, lift, and drag coefficients are compared with experimental data. The effects of heavy gas on the details of the flow are investigated based on computed boundary-layer and skin-friction data.
In general, the predictions in SF6 vary little from those in air. Within the limitations of the computational method, the results presented are sufficiently encouraging to warrant further experiments. A method of making essentially stoichiometric uranium monocarbide by pelletizing a mixture of uranium tetrafluoride, silicon, and carbon and reacting the mixture at a temperature of approximately to deg C until the reaction goes to completion, forming uranium monocarbide powder and volatile silicon tetrafluoride, is described.
The powder is then melted to produce uranium monocarbide in massive form. The voltage on bare signal or control wires accessible to personal contact shall not exceed 40 volts. Where metallic tools or equipment can come in contact with trolley wires or bare powerlines, the lines shall be guarded or deenergized. Where metallic tools or equipment can come in contact with trolley wires or bare powerlines, the lines shall be guarded Supersonic Bare Metal Cluster Beams.
Technical Progress Report, March 16, - April 1, There have been four major areas of concentration for the study of bare metal cluster beams: neutral cluster, chemical reactivity, cold cluster ion source development both positive and negative , bare cluster ion ICR ion cyclotron resonance development, and photofragmentation studies of bare metal cluster ions. The recovery of uranium values from uranium ore such as pitchblende is described. The ore is first dissolved in nitric acid, and a water soluble nitrate is added as a salting out agent.
The resulting feed solution is then contacted with diethyl ether, whereby the bulk of the uranyl nitrate and a portion of the impurities are taken up by the ether. This acid ether extract is then separated from the aqueous raffinate, and contacted with water causing back extractioa of the uranyl nitrate and impurities into the water to form a crude liquor. After separation from the ether extract, this crude liquor is heated to about deg C to obtain molten uranyl nitrate hexahydratc. After being slightly cooled the uranyl nitrate hexahydrate is contacted with acid free diethyl ether whereby the bulk of the uranyl nitrate is dissolved into the ethcr to form a neutral ether solution while most of the impurities remain in the aqueous waste.
Rethinking biopower: posthumanism, bare life, and emancipatory work. This article answers a call, recently published in Advances in Nursing Science, to more fully explore the use of Italian political philosopher Giorgio Agamben's theory of biopower in nursing research and scholarship. Giorgio Agamben argues that biopower is not a modern phenomenon, and critical analysis of the historical origins of Western political practice shows how humanist discourse has been complicit in a long tradition of marginalization and violence, accomplished in each era by designating certain classes of human beings as " bare life.
This patent deals with the separation of rare earth and other fission products from neutron bombarded uranium. This is accomplished by melting the uranium in contact with either thorium oxide, maguesium oxide, alumnum oxide, beryllium oxide, or uranium dioxide. The melting is preferably carried out at from deg to deg C in an inert atmosphere, such as argon or helium. During this treatment a scale of uranium dioxide forms on the uranium whtch contains most of the fission products.
TNO developed a toolbox to estimate the probability of a violent event on a ship or other platform, when the munition bunker is hit by e. To obtain the proper statistical output, several millions of calculations are needed to obtain a reliable estimate. Because millions of different scenarios have to be calculated, hydrocode calculations cannot be used for this type of application, but a fast and good engineering solutions is needed.
At this moment the Haskins and Cook-model is used for this purpose. To obtain a better estimate for covered explosives and munitions, TNO has developed a new model which is a combination of the shock wave model at high pressure, as described by Haskins and Cook, in combination with the expanding shock wave model of Green. This combined model gives a better fit with the experimental values for explosives response calculations, using the same critical energy fluence values for covered as well as for bare explosives. In this paper the theory is explained and results of the calculations for several bare and covered explosives will be presented.
To show this, the results will be compared with the experimental values from literature for composition B, Composition B-3 and PBX BackgroundAortic thrombi in the ascending aorta or aortic arch are rare but are associated with a relevant risk of major stroke or distal embolization. Although stent grafting is commonly used as a treatment option in the descending aorta, only a few case reports discuss stenting of the aortic arch for the treatment of a thrombus.
The use of bare metal stents in this setting has not yet been described. MethodsWe report two cases of ascending and aortic arch thrombus that were treated by covering the thrombus with an uncovered stent. Both procedures were performed under local anesthesia via a femoral approach. ResultsBoth procedures were successfully performed without any periprocedural complications. Postoperative recovery was uneventful. In both cases, no late complications or recurrent embolization occurred at midterm follow-up, and control CT angiography at 1 respectively 10 months revealed no stent migration, freely perfused supra-aortic branches, and no thrombus recurrence.
ConclusionTreating symptomatic thrombi in the ascending aorta or aortic arch with a bare metal stent is feasible. This technique could constitute a minimally invasive alternative to a surgical intervention or complex endovascular therapy with fenestrated or branched stent grafts.
Experiments on injected charges in pentacene single crystals reveal mobilities typical of inorganic semiconductors and temperature dependence for T bare wide effectively infinite band description work for pentacene for T bare finite band description compatible with those data? These questions are answered by modifications of a theory originally constructed for inorganic materials and a newly developed mobility theory. Teaching-learning-based optimization TLBO algorithm which simulates the teaching-learning process of the class room is one of the recently proposed swarm intelligent SI algorithms.
In this method, each learner of teacher phase employs an interactive learning strategy, which is the hybridization of the learning strategy of teacher phase in the standard TLBO and Gaussian sampling learning based on neighborhood search, and each learner of learner phase employs the learning strategy of learner phase in the standard TLBO or the new neighborhood search strategy.
To verify the performance of our approaches, 20 benchmark functions and two real-world problems are utilized. The results indicate that the proposed algorithm is competitive to some other optimization algorithms. Bare -bones teaching-learning-based optimization. A process is described for reducing the extractability of ruthenium, zirconium, and niobium values into hexone contained in an aqueous nitric acid uranium -containing solution. The solution is made acid-deficient, heated to between 55 and 70 deg C, and at that temperature a water-soluble inorganic thiosulfate is added.
By this, a precipitate is formed which carries the bulk of the ruthenium, and the remainder of the ruthenium as well as the zirconium and niobium are converted to a hexone-nonextractable form. The rutheniumcontaining precipitate can either be removed from the solu tion or it can be dissolved as a hexone-non-extractable compound by the addition of sodium dichromate prior to hexone extraction.
The primary outcome was the rebubbling rate at the final observation. The secondary outcomes were 1 the graft detachment rate, 2 mean difference MD in best-corrected visual acuity BCVA , 3 manifest refraction spherical equivalent, 4 central corneal thickness CCT , 5 percentage of endothelial cell loss ECL , and 6 rate of pupillary block by the final observation. Statistical analysis was performed using RevMan5. Five retrospective studies were included, assessing eyes SF6 ; air The main indication for surgery was Fuchs endothelial dystrophy SF6 Overall, studies were of moderate to good methodological quality.
To perform a fellow eye comparison of outcomes and complications when using air or sulfur hexafluoride SF6 gas as a tamponade in Descemet membrane endothelial keratoplasty DMEK. One hundred thirty-six eyes of 68 consecutive patients who underwent uneventful DMEK in both eyes for Fuchs endothelial corneal dystrophy were included in this retrospective study.
All eyes received laser iridotomy on the day before DMEK. Thirteen of 68 eyes There were no significant differences in preoperative and postoperative best-corrected visual acuity, endothelial cell density, and corneal volume within 3-month follow-up. Our results confirm the previously reported better graft adhesion when using an SF6 gas tamponade in DMEK without increased endothelial cell toxicity. The rate of pupillary block in eyes with an SF6 gas tamponade was comparable to that with an air tamponade.
The main outcome measure was the graft detachment rate; univariate and multivariate analyses were performed. A retrospective chart review of patients who underwent DMEK with either air or SF6 tamponade: 41 eyes received air tamponade group 1 and 41 received SF6 tamponade group 2. Best spectacle-corrected visual acuity, endothelial cell density, and complications including graft detachment and elevated intraocular pressure were compared.
Mean best spectacle-corrected visual acuity improved from 1. Rebubbling was performed in There was 1 primary graft failure in each group. Use of air with it being readily available and short acting is a good method of Descemet membrane tamponade in noniridectomized DMEK. Decomposition of potent greenhouse gas sulfur hexafluoride SF6 by Kirschsteinite-dominant stainless steel slag.
In this investigation, kirschsteinite-dominant stainless steel slag SSS has been found to decompose sulfur hexafluoride SF6 with the activity higher than pure metal oxides, such as Fe2O3 and CaO.
Chemical aspects of nuclear fuel fabrication processes
In addition, we have found that oxygen significantly inhibited the SF6 decomposition with SSS while H2O did not, which could be explained in terms of reaction pathways. This research thus demonstrates that waste material SSS could be potentially an effective removal reagent of greenhouse gas SF6. Process for electroslag refining of uranium and uranium alloys. A process is described for electroslag refining of uranium and uranium alloys wherein molten uranium and uranium alloys are melted in a molten layer of a fluoride slag containing up to about 8 weight percent calcium metal.
The calcium metal reduces oxides in the uranium and uranium alloys to provide them with an oxygen content of less than parts per million. Modeling and control study of the NASA 0. The modified tunnel will provide high Reynolds number flow on aerodynamic models with two different test gases.
The document details a study of the SF6 tunnel performance boundaries, thermodynamic modeling of the tunnel process, nonlinear dynamical simulation of math model to yield tunnel responses, the closed loop control requirements, control laws, and mechanization of the control laws on the microprocessor based controller. A method is described for recovering uranium values from uranium bearing phosphate solutions such as are encountered in the manufacture of phosphate fertilizers. The solution is first treated with a reducing agent to obtain all the uranium in the tetravalent state.
Following this reduction, the solution is treated to co-precipitate the rcduced uranium as a fluoride, together with other insoluble fluorides, thereby accomplishing a substantially complete recovery of even trace amounts of uranium from the phosphate solution. This precipitate usually takes the form of a complex fluoride precipitate, and after appropriate pre-treatment, the uranium fluorides are leached from this precipitate and rccovered from the leach solution.
A pyrometallurgical method for processing nuclear reactor fuel elements containing uranium and fission products and for reducing uranium compound; to metallic uranium is reported. If the material processed is a uranium compound, the sollvent is an alloy of zinc and magnesium and the remaining steps are the same. In this study, we evaluate the doping concentrations of bare silicon wafers by noncontact capacitance voltage C V measurements. The metal-air-insulator-semiconductor MAIS method enables the measurement of C V characteristics of silicon wafers without oxidation and electrode preparation.
This method has the advantage that a doping profile close to the wafer surface can be obtained. The experimental results obtained from the two methods showed good agreement. The result indicated a significant reduction of the doping concentration near the wafer surface. This observation is attributed to the well-known deactivation of boron with atomic hydrogen which permeated the silicon bulk during the polishing process. Diurnal emissivity dynamics in bare versus biocrusted sand dunes.
Land surface emissivity LSE in the thermal infrared depends mainly on the ground cover and on changes in soil moisture. The LSE is a critical variable that affects the prediction accuracy of geophysical models requiring land surface temperature as an input, highlighting the need for an accurate derivation of LSE. The primary aim of this study was to test the hypothesis that diurnal changes in emissivity, as detected from space, are larger for areas mostly covered by biocrusts composed mainly of cyanobacteria than for bare sand areas.
Different land-use practices by the two countries have resulted in exposed, active sand dunes on the Egyptian side Sinai , and dunes stabilized by biocrusts on the Israeli side Negev. Since biocrusts adsorb more moisture from the atmosphere than bare sand does, and LSE is affected by the soil moisture, diurnal fluctuations in LSE were larger for the crusted dunes in the 8.
The results indicate that LSE is sensitive to minor changes in soil water content caused by water vapor adsorption and can, therefore, serve as a tool for quantifying this effect, which has a large spatial impact. As biocrusts cover vast regions in deserts worldwide, this discovery has repercussions for LSE estimations in deserts around the globe, and these LSE variations can potentially have considerable effects on geophysical models from local to regional scales.
A process is given for purifying a uranium -base nuclear material. The nuclear material is dissolved in zinc or a zinc-magnesium alloy and the concentration of magnesium is increased until uranium precipitates. Nickel coatings on uranium and various methods of obtaining such coatings are described. Specifically disclosed are such nickel or nickel alloy layers as barriers between uranium and aluminum- silicon, chromium, or copper coatings.
Uranium production in Romania. This article reviews uranium production in Romania. Geological aspects of the country are discussed, and known uranium deposits are noted. Uranium mining and milling activities are also covered. A method of obtaining substantially pure uranium from a uranium composition contaminated with light element impurities such as sodium, magnesium, beryllium, and the like is described.
An acidic aqueous solution containing tetravalent uranium is treated with a soluble molybdate to form insoluble uranous molybdate which is removed. This material after washing is dissolved in concentrated nitric acid to obtaln a uranyl nitrate solution from which highly purified uranium is obtained by extraction with ether. Nayegandhi, Amar; Brock, John C. These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth BE topography were produced collaboratively by the U.
This project provides highly detailed and accurate datasets of the northeast coastal barrier islands in New York and New Jersey, acquired April and May , The datasets are made available for use as a management tool to research scientists and natural resource managers. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength nanometer Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue RGB digital camera, a high-resolution multi-spectral color infrared CIR camera, two precision dual-frequency kinematic carrier-phase GPS receivers and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample.
The nominal EAARL platform is a twin-engine Cessna aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations.
Science Highlights, July 22, 2015
This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Wayne; Miner, Michael D. These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth BE topography were produced as a collaborative effort between the U. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March , The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue RGB digital camera, a high-resolution multi-spectral color infrared CIR camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample.
Elevation measurements were collected over the survey area using the. This project provides highly detailed and accurate datasets of the Vicksburg National Military Park in Mississippi, acquired on March 6, Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed. The purpose of this project is to provide highly detailed and accurate datasets of select barrier islands and peninsular regions of Louisiana, Mississippi, Alabama, and Florida, acquired on June , The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue RGB digital camera, a high-resolution multi-spectral color infrared CIR camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit which provide for submeter georeferencing of each laser sample.
Elevation measurements were collected over the survey area using. Wayne; Nagle, David B. These remotely sensed, geographically referenced elevation measurements of lidar-derived bare -earth BE and submerged topography datasets were produced collaboratively by the U. This project provides highly detailed and accurate datasets of a portion of the Chandeleur Islands, acquired March 3, The datasets are made available for use as a management tool to research scientists and natural-resource managers. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength nanometer lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously.
The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive lidar, a down-looking red-green-blue RGB digital camera, a high-resolution multispectral color-infrared CIR camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. A single pilot, a lidar operator, and a data analyst constitute the crew for most survey operations. In the prior art processing of uranium ores, the ore is flrst digested with nitric acid and filtered, and the uranium values are then extracted tom the filtrate by contacting with an organic solvent.
The insoluble residue has been processed separately in order to recover any uranium which it might contain. The improvement consists in contacting a slurry, composed of both solution and residue, with the organic solvent prior to filtration. Tbe result is that uranium values contained in the residue are extracted along with the uranium values contained th the solution in one step.
The production of uranium metal by the reduction of uranium tetrafluoride is described. A process is presented for recovering uranium values from calutron deposits. The process consists in treating such deposits to produce an oxidlzed acidic solution containing uranium together with the following imparities: Cu, Fe, Cr, Ni, Mn, Zn. The uranium is recovered from such an impurity-bearing solution by adjusting the pH of the solution to the range 1. This results in the precipitation of uranium peroxide which is substantially free of the metal impurities in the solution.
The peroxide precipitate is then separated from the solution, washed, and calcined to produce uranium trioxide. The separation of uranium from a mixture of uranium and thorium by organic solvent extraction from an aqueous solution is described.