Top PDF The Separation of Gaseous Isotopes by Diffusion

The Separation of Gaseous Isotopes by Diffusion

The Separation of Gaseous Isotopes by Diffusion

with an apparatus containing fourteen mercury dif'fusion pumps, show the separation to be the same as for rr.ixtures of carbon dioxide and argon, for which the mass ratio, 44:40, is the [r]

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Single microphone speech separation by diffusion-based HMM estimation

Single microphone speech separation by diffusion-based HMM estimation

In this work, we presented two novel approaches for estimating temporal FHMM on manifolds based on the diffusion framework, that are non-iterative and rigor- ously accurate. The core of our approach is to utilize the asymptotics of the Markov random walk, induced on the graph representation of a high-dimensional data source, to decouple the estimation of the latent state space (states and transition probabilities), and the estimation of the emission (observation) p.d.f.s. We applied the proposed schemes to the task of separating two speakers using a single-microphone, that provides a viable baseline to validate the effectiveness of the proposed scheme. In par- ticular, we derived two FHMM-based separation schemes, where the first estimates the HMM of each speaker in the diffusion domain, and then utilizes the log-max approxi- mation to infer the FHMM model. The second, formulates the speech separation problem entirely in the embed- ded domain, as the derivation of two FHMM models, each adapted to the diffusion embedding of a particular speaker. The inferred states are used to construct mask- ing functions to unmix the speech signal. Two masking schemes are presented, utilizing either soft or hard masks. We experimentally evaluated the proposed schemes using both objective metrics and informal subjective listening tests, for male-female, male-male, and female-female mix- tures. The HFHMM scheme is shown to yield comparable and even slightly better performance than [36], while the DFHMM scheme exhibits performance degradation, probably due to sub-optimal embedding (that uses the Nyström extension). The MIXMAX [35] and the iterative algorithm by Hu and Wang [38] had the best SAR and SDR score, although the HFHMM and Roweis methods with soft masks obtained good SAR as well. The pro- posed HFHMM scheme obtained the best SIR scores on average among all tested algorithms, with insignificant advantage over Hu and Wang method. Informal listening tests demonstrate the insufficiency of the current solution to fully recover the two speakers. Although the separation capabilities of the MIXMAX and Hu and Wang algorithms are slightly better than those of the proposed schemes, the differences are quite marginal, according to our sub- jective evaluation. Several sound clips are available on our website.
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Understanding the solution-diffusion mechanism in gas separation membrane for engineering students

Understanding the solution-diffusion mechanism in gas separation membrane for engineering students

Th€ solution-diffusion model is the nost sidely used rmnspon model for permealron ir pol),mer membrane. The model allows the membrane separation process of dialysis, reverse o[r]

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Trennung von terphenylgemischen durch thermodiffusion  EUR 1895  = Separation of terphenylgemischen by thermochemical diffusion  EUR 1895

Trennung von Terphenylgemischen durch Thermodiffusion. EUR 1895. = Separation of terphenyl mixtures through thermal diffusion. EUR 1895.

For a commercial-grade terphenyl mixture 2.7 wt% biphenyl, 10.4 wt% high boiler components, tests performed in a thermal diffusion column disclosed an enrichment of biphenyl and p-terphe[r]

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Separation of type and grade in cervical tumours using non-mono-exponential models of diffusion-weighted MRI.

Separation of type and grade in cervical tumours using non-mono-exponential models of diffusion-weighted MRI.

It is increasingly recognised that the observed diffusion- weighted magnetic resonance imaging (DW-MRI) signal attenuation in biological tissues is not completely de- scribed by a Gaussian process [1 – 5]. The use of non- mono-exponential models provides a better description of the DW-MRI signal, and parameters derived from these models allow more detailed investigation of differ- ences between tumour sub-types or inter-tumour hetero- geneity [6–11] and may also provide an earlier indication of response to treatment [12, 13]. However, use of a model with a large number of additional parameters risks over-fitting the data and may be sensitive to noise char- acteristics of the system rather than structural properties of the tumour or normal tissue. The potential for exploiting these parameters to describe tumour pheno- types remains substantial, but data relating them to the micro-structural properties of tumours or normal tissues is limited, particularly in body applications. Owing to the complexity of tissue and tumour micro-structure within a voxel [14], these models can at least be viewed as phe- nomenological descriptions of the data and in addition have demonstrable value as empirical markers of tissue status [15]. Nevertheless, their relationship to tissue micro-structural properties is an important topic of ongo- ing exploration [16, 17].
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Numerical experiments on vapor diffusion in polar snow and firn and its impact on isotopes using the multi-layer energy balance model Crocus in SURFEX v8.0

Numerical experiments on vapor diffusion in polar snow and firn and its impact on isotopes using the multi-layer energy balance model Crocus in SURFEX v8.0

two kinds of approaches are possible. On the one hand, it would be useful to realize simulations adapted to on-site ex- periments, such as the one by van der Wel et al. (2015). This would allow for the verification of how diffusion can be im- proved in the model. For instance, previous studies have sug- gested that water vapor diffusivity within the snow porosity may be underestimated by a factor of 5 (Colbeck, 1983), but this is debated (Calonne et al., 2014). On the other hand, we also believe that other processes should probably be consid- ered to explain the remaining attenuation. Ventilation is an additional process that has already been implemented in the snow water isotopic model of Town et al. (2008) and Neu- mann (2003). Because of strong porosity and sensitivity to surface wind and relief, ventilation is probably as important as diffusion in the top of the firn, even if diffusion is expected to be more effective at greater depths. For the Dome C sim- ulation (Fig. 8), the slope d(δ 18 O)/dz decreases slowly, indi- cating that diffusion remains almost as active at 60 cm than at 10 cm of depth. Neumann (2003) indicates that at Tay- lor Mouth the diffusion becomes the only process of vapor transport below 2 m of depth. For Dome C, for a tempera- ture gradient of 3 ◦ C m −1 , we compute an average speed due to diffusion of 3 × 10 −6 m s −1 . This is comparable to an air speed due to wind pumping of about 3 × 10 −6 m s −1 within the top meters of snow at WAIS (Buizert and Severinghaus, 2016). We conclude that, in as much as these results can be applied to Dome C, the two processes would have a compa- rable impact at this site in the first meters of snow. The next step for Crocus-iso development is thus to implement ven- tilation. Finally, we are also aware that in Antarctic central regions, the wind reworking of the snow has a strong effect in shaping the isotopic signal. A combination of stratigraphic noise and diffusion could indeed be responsible for creating isotopic cycles of non-climatic origin in the firn (Laepple et al., 2017). Wind reworking may also contribute to attenuation by mixing together several layers deposited during different seasons.
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Quadrupole moments in the cadmium isotopes

Quadrupole moments in the cadmium isotopes

Coulomb-nuclear interference effects can severely distort the results of reorientation experiments carried out at too high a bombarding energy. The quadrupole moment obtained diverges rapidly from the true value if data obtained at energies above the barrier are included in the analysis. The maximum safe bombarding energy may be defined as the energy at which the nuclear contribution is no greater than 1% of the total cross section. The Coulomb barrier in 114Cd has been studied extensively with 4He projectiles, because of discrepancies among the various measurements of the B(E2, 0+-*2+) value in 114Cd. Some of these differences were attributed to the use of too high bombarding energies. A list of these experiments in which the Coulomb barrier was investigated in 114Cd and also in the other cadmium isotopes is given in table 4.2 together with the results obtained.
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The Inner Gaseous Disks Of Herbig Be Stars

The Inner Gaseous Disks Of Herbig Be Stars

Optical and NIR atomic lines are used to study the hot, atomic gaseous region. The disk re- gion beyond the gaseous disk receiving direct radiation from the star is expected to have a thin surface layer with atomic gas; hence, the emission seen in the spectrum can arise from a large extended area. The atomic gaseous region can range from 0.01 to a few AUs in size depending on the intensity of the stellar radiation. In the region beyond the atomic gaseous disk, where the temperatures are cooler, molecular gas is expected. As the temperature decreases, thee conditions are viable for the dust to exist and a mixture of warm dust and molecular gas is ex- pected. NIR molecular emission lines and NIR / Mid-IR (MIR, hereafter) interferometry is used to understand the structure of this region. Beyond this region, cooler gas and dust are detected using millimeter and submillimeter interferometry. The region beyond the atomic gaseous disk can range anywhere in size from 0.1 to 100s of AUs, including the dusty disk (Dullemond & Monnier, 2010). The outer, dusty region of the disk is comparatively well studied, but currently very little is known about the inner, gaseous region.
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The metabolism of gaseous n alkanes by bacteria

The metabolism of gaseous n alkanes by bacteria

similarities between the, as yet, unisolated gaseous alkane monooxygenases and MMOs. Specifically, the similarity between the specificity of these enzymes lies in their ability to oxidize a range of n-alkanes (usually about eight alkanes) and to oxidize alkenes to the corresponding epoxides. In addition, bacteria able to use C1-C10 n—alkanes can usually convert the longer— chain n-alkanes (greater than C4) to secondary alcohols (for MMO literature, see Leadbetter A Foster, 1960; Hou ¿t , 1979? Hou et a l .. 1980; Colby et^ ^ . , 1977). The similarity between the substrates oxidized and the products formed from them could be an indication of some degree of mechanistic similarity between all alkane monooxygenases, but, as with MMOs, it is not possible to decide whether this is an adaptation for survival or simply a dictate of the enzyme mechanism required for alkane oxidation.
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Quadrupole moments in the lead isotopes

Quadrupole moments in the lead isotopes

204,206pb are w ithin the mass range A = 180 - 201. Both tungsten and tantalum are included in this mass range and although these materials are often used for crucibles in target manufacture, in the present work a carbon crucible was used. Mercury contamination, which could affect the 180 data, is not expected to be a problem since the targets were never exposed to a vacuum system employing mercury diffusion pumps. The only other contaminants which could affect the data are Pt, Au, and some rare earths; it is unlikely that any of these
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Stable water isotopes in the MITgcm

Stable water isotopes in the MITgcm

The seawater oxygen isotope ratio and salinity are controlled by the same processes such as evaporation, precipitation, river runoff and sea ice formation. In this way, they are lo- cally linearly related, resulting in a slope that varies between 0.1 ‰ psu −1 in low latitudes and up to 1 ‰ psu −1 in high lat- itudes. However, water that is evaporated from the ocean sur- face does not carry any salt, but it contains stable water iso- topes. The agreement between the simulated slope and obser- vational slope in the tropical regions is good but significantly weaker in the midlatitudes. This mismatch is mainly caused by the stable water isotopes since the overall comparison to observed SSS is quite good and comparable with other ocean models (cf. Sect. 4.1).
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07 Isotopes and Average Atomic Mass

07 Isotopes and Average Atomic Mass

Chemists face a situation similar to the one described above. Because all the atoms in a given element do not have the same number of neutrons, they do not all have the same mass. For example, magnesium has three naturally occurring isotopes. It is made up of 79% magnesium-24, 10% magnesium-25, and 11% magnesium-26. Whether the magnesium is found in a supplement tablet (like the ones on the right) or in seawater as Mg(OH) 2 , it is always made up of these three isotopes in the same

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Applications of hydrogen isotopes in the life sciences

Applications of hydrogen isotopes in the life sciences

The unique MS-pattern obtained from natural and labeled isotopologues drastically simplifies analysis and provides a wealth of inspiring information and previously unprecedented levels of insight from a wide and continuously growing range of applications in many disciplines within the life sciences and beyond. The ability to measure naturally abundant isotope ratios has paved the way for a number of scientific breakthroughs in forensic sciences, geochemistry, ecology, and physiology. Additionally, analytical approaches incorporating stable isotopes have delivered now indispensable tools for relative and absolute quantification, for delineation of cellular metabolism, and for investigation of responses to various stimuli. Having stated this, perhaps most importantly, the employment of such methods provides a dynamic view on biosynthethic pathways, protein turnover, and systems-wide metabolic networks. Indeed, further expansion of isotope labeling to the whole-systems level, together with recent advances in bioinformatics, will bring us closer to a true systems biology understanding.
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The Global Network of Isotopes in Rivers (GNIR): integration of water isotopes in watershed observation and riverine research

The Global Network of Isotopes in Rivers (GNIR): integration of water isotopes in watershed observation and riverine research

The isotopic composition of precipitation has been mon- itored for over 50 years worldwide through the Global Net- work of Isotopes in Precipitation (GNIP), a joint initiative of the International Atomic Energy Agency (IAEA), the World Meteorological Organization (WMO), and collaborating in- stitutions as well as individuals (Rozanski et al., 1993; Ag- garwal et al., 2010; IAEA/WMO, 2015). In order to fill iso- topic data gaps between the well-known continental precipi- tation inputs to terrestrial landscapes and the aggregated and altered riverine discharges to the sea, a new Global Network of Isotopes in Rivers (GNIR) was initiated as part of the IAEA Water Resources Programme. GNIR began as a pilot project in 2002–2005 and focussed on the stable isotopes and tritium content of various world river catchments (Vitvar et al., 2007; Michel et al., 2014). The aim of the GNIR pro- gramme is to collect and disseminate time-series and synop- tic collections of riverine isotope data from the world’s rivers and to inform a range of scientific disciplines including hy- drology, meteorology and climatology, oceanography, lim- nology, and aquatic ecology.
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The Measurement Situation of Concentrations of Gaseous Hydrocarbons

The Measurement Situation of Concentrations of Gaseous Hydrocarbons

It is commonly believed that exhausted fume from gasoline with lead is extremely harmful to human nature, thus there is a new standard to appeal people to use leadless gasoline in 1970s [1]. The substitution for the lead are alcohols and ethers. The gasoline with alcohols, ethers and other oxide can rise the octane number which means that the gasoline can enhance the ability of anti-vibration, meanwhile this type of gasoline can also drop the volatility. The concentration of the exhausted fume and some volatilize gas from vehicles are in relation to the oxide of fuels. The main purpose of this paper is to measure the concentration of gaseous hydrocarbons.
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Gaseous detonation driven fracture of tubes

Gaseous detonation driven fracture of tubes

This investigation began with the linear elastic response having CJ speeds near the material shear wave speed. One important new result was that a resonance in transverse shear near the shear wave speed, similar to the flexural resonance at the first critical load speed, was found numerically. The study continued with observations in fracture without intentionally applied static loading. Crack branching and helical curving were observed for different initial flaw sizes. A fracture threshold model, first of its kind for gaseous detonation-loaded tubes, was developed and compared well with experimental data. Next, crack speeds, fracture behavior, and strain of detonation- loaded specimens were compared, for the first time, with specimens quasi-statically loaded by gaseous nitrogen and hydraulic oil. With the specimen geometry, flaw geometry, and pressure magnitude nominally identical, the difference in results was striking, and these were analyzed in terms of fluid mechanics and energy storage.
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The Gaseous Oxides of the Platinum Metals134-139

The Gaseous Oxides of the Platinum Metals134-139

Thus if we compare the weight losses of a piece of platinum which is brought suc- cessively to equilibrium with gases of known oxygen partial pressure passing at a k[r]

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Thermophoresis of Carboxylic Nanotubes in Gaseous Atmosphere

Thermophoresis of Carboxylic Nanotubes in Gaseous Atmosphere

The present paper deals with motion of carbon nanotubes in a temperature gradient field. A determined-static theory of nanosized particles’ thermophores is developed. Analytical expressions for thermophoretic velocity and force of ultramicroheterogeneous particles in a gaseous atmosphere under near-normal conditions are provided. The calculations performed according to the suggested theory, as applied to closed carbon nanotubes, found the value of dimensionless velocity of thermophoresis. In accordance with the proposed hypothesis, Waldman’s limit is achieved, which is expressed in constancy of thermophoretic velocity within the interval of the Knudsen para- meter change from 10 to 100. In addition, it is found out that under conditions defined below, velocity of ther- mophoresis is independent of the length of a carboxylic nanotube. A good agreement with experiments is reached, which makes it possible to assume correspondence of the theory to the physical truth.
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Orbital evolution of planetesimals in gaseous disks

Orbital evolution of planetesimals in gaseous disks

In order to evaluate the drag force due to nebula gas, the disk model is set as follows. A gaseous disk rotates around a central object with mass M ∗ , which is axisymmetric and in a steady state. In a cylindrical coordinate system (r, θ , z), the gas density ρ is defined from the force equilibrium in the z direction in a vertical isothermal disk as

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The influence of foreign gases on gaseous spectra

The influence of foreign gases on gaseous spectra

While considering the influence of foreign gases on gaseous spectra, it thought that the presence of water vapour may modify the general spectrum of the gas under consideration, besides producing the known water vapour bands. It was found that eaperlments had already been carried out in this connection. Newman (17) found that the continuous spectrum of hydrogen could be produced at low pressures, by means of an electric arc passed between cold electrodes in a rarefied atmosphere of hydrogen. An intermittent electrical discharge was passed between two iron electrodes in a discharge tube, and between one of these electrodes and a third one a potential difference of 200 volts was applied.continuously. The tube contained hydrogen at a pressure of 10 mm mercury. If the hydrogen was not dry, the water vapour bands, particularly those at ^ 3064 and \ 2811, were prominent, together with a few of the lines oft he Balmer series, but there w a s a o
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