Deuterium Levels Research Articles

External ion beam analysis of the TFTR bumper limiters

Abstract Following the 1988 operational campaign of the Tokamak Fusion Test Reactor (TFTR), 63 bumper-limiter tiles were removed for analysis. Each tile was analyzed ex vacuo for deuterium contamination. The total deuterium content was obtained using a new two-point approximation technique for exponential depth profiles. Several tiles were further analyzed to provide detailed two- and three-dimensional mapping and line scans down the sides of tiles for deuterium. Comparison of the deuterium data for the 1987 and 1988 campaigns indicates that deuterium deposition does not depend solely upon total integrated fueling. D fueling for the 1988 campaign was comparable to proposed fueling for future DT shot scenarios in TFTR. 1988 deuterium data lead to a tritium inventory estimate of ∼ 3 g T in the lirniter of TFTR for this fueling level. Scans along the side edges of limiter tiles indicate that the edges retain high levels of deuterium and are thus an important factor in T inventory estimates.

A Search for Neutrons in Single-Phase Palladium-Deuterium

A palladium rod is charged to relatively high levels of deuterium without passing through the two-phase region of this system. This is accomplished by a combination of gaseous high-temperature–high...

The use of in vivo2H NMR spectroscopy to investigate the effects of obesity and diabetes mellitus upon lipid metabolism in mice

In vivo deuterium magnetic resonance spectroscopy was used to measure fat utilization rates in diabetic and non-diabetic obese and non-obese mice. Monosodium glutamate-treated mice were used as a model for obesity, and diabetes was induced by administration of streptozotocin. Deuterium levels were enhanced by addition of D2O to drinking water (10% v/v) for a period of 14 days. The deuterium magnetic resonance signals of the body water and adipose tissue were then monitored to measure the rate of deuterium loss from the body. The rates of fat utilization for obese mice were significantly lower (75%, p less than 0.05) (halflife, t1/2 = 113 +/- 13 days) than the rates for non-obese mice (t1/2 = 30.0 +/- 9.0 days). The induction of diabetes caused a large (90%) but proportionally similar increase in fat utilization for both groups of mice (obese, t1/2 = 11.0 +/- 5.2; non-obese, t1/2 = 3.0 +/- 0.9). The results suggest that the induction of diabetes in obese mice does not affect the utilization of fat as a metabolic fuel. These preliminary studies indicate that deuterium magnetic resonance spectroscopy may be a useful technique for non-invasive determination of the rates of fat utilization in vivo.

Deuterium oxide as a tracer for measurement of compliance in pediatric clinical drug trials

We tested the hypothesis that a deuterium oxide (D2O) tracer could discriminate among patterns of clinically significant, imperfect compliance during drug trials. A model was developed to predict deuterium concentration during multiple dose regimens. After developing a regression equation to predict one of the model parameters for children, we selected healthy children (N = 20) at random to receive one of five 10-day D2O regimens. Five urine samples were obtained from each child during 15 days and analyzed for deuterium level by mass spectrometry. Each child's height, weight, age, and the first four urinary deuterium levels were used to estimate the amount and timing of deuterium administration. These estimates were compared with the five regimens to determine the closest match between estimate and regimen. The closest matching regimen was the regimen actually administered to 19 (95%) of the 20 children. Two of these children had D2O administration estimates that could be confused with another regimen. The correlation between the model's predicted levels and the measured levels of all urine samples was 0.96. We conclude that a D2O tracer shows excellent promise as a quantitative method of assessing compliance with liquid medications under specified conditions.

Environmentally stable isotopes and groundwater recharge in the eastern Nile delta

In the study oxygen‐18 and deuterium levels in groundwater and surface water samples are used in studying the source of recharge. The results show that the area bounded by the Nile and the Ismailia Canal is recharged directly from surface water. In some localities the recharge occurs indirectly (after evaporation). There is a mixing between different sources of water, recent water (surface water), old water (paleowater), flood water (rain) and sea water (connate) in some wells. Interpretation of the isotopic composition data indicates that the Nile branch (Damietta) and Ismailia Canal (surface water) are the main sources of recharge to groundwater.

Spin-polarized deuterium in magnetic traps.

We have calculated the spin-exchange two-body rate constants associated with the population dynamics of the hyperfine levels of atomic deuterium as a function of magnetic field in the Boltzmann zero-temperature limit. Results indicate that a gas of low-field--seeking deuterium atoms trapped in a static magnetic field minimum decays rapidly into an ultrastable gas of doubly spin-polarized deuterium. We also discuss the temperature dependence of various effects.

Determination of deuterium level in biological fluids by isotope ratio mass spectrometry.

Water is produced by vacuum sublimation of biological fluids directly into reaction vessels in preparation for reduction using zinc. Following heating to 450 degrees C the hydrogen produced is admitted directly to the mass spectrometer. The standard derivation, sigma 10 of analysis of water samples was 1.08-1.23% while for blood plasma sigma 6 = 2.02-2.62%. The method allows the determination of very low levels of deuterium in biological fluids, thus allowing very small doses of deuterium oxide to be used in studies of body water in animals and possibly humans.

Effects of organophosphates on presynaptic events in the vascularly perfused phrenic nerve-hemidiaphragm preparation from the rat

A vascularly perfused phrenic nerve-hemidiaphragm preparation from the rat was developed to study effects of physostigmine and some organophosphate inhibitors on the synthesis and release of endogenous and deuterium-labelled (choline—D 9) acetylcholine (ACh) as well as the presynaptic uptake of choline. Choline and ACh were determined by combined gas chromatography/mass spectrometry. Without stimulation the endogenous levels of ACh were 320 pmole/hemidiaphragm for unlabelled and <1 pmole/hemidiaphragm of deuterium-labelled ACh. After stimulation at 15 Hz for 1 hr, 460 pmole/hemidiaphragm of unlabelled and 15 pmole/hemidiaphragm of deuterium-labelled ACh were found. Without stimulation the release of unlabelled ACh was 6 pmole/min/hemidiaphragm and for deuterium-labelled 0.2 pmole/min/hemidiaphragm. Evoked release (15 Hz, 1 hr) was 22 pmole/min/hemi-diaphragm for unlabelled and 1.8 pmole/min/hemidiaphragm for deuterium labelled ACh. During stimulation and treatment with high concentrations (10 −5–10 −4 M) of soman, DFP and Vx the level of unlabelled endogenous ACh increased, but the level of deuterium labelled ACh decreased in the diaphragm. During stimulation and treatment with these inhibitors the release of both unlabelled and labelled ACh decreased. During treatment with high concentrations (10 −5–10 −4M) of sarin and physostigmine there were no changes in endogenous levels or release of unlabelled or deuterium labelled ACh. The different effects of cholinesterase inhibitors are probably linked to the synthesis and release mechanism of ACh rather than to the choline uptake mechanism.

Spin-Polarized Deuterium: Stabilization in Magnetic Traps

We report on a calculation of the spin-exchange two-body rate constants associated with the population dynamics of the hyperfine levels of atomic deuterium as a function of magnetic field in the Boltzmann zero temperature limit. We find that a gas of low field seeking deuterium atoms trapped in a static magnetic field minimum decays rapidly into an ultra stable gas of doubly spin-polarized deuterium.

Surface analysis of 1984/85 Tokamak Fusion Test Reactor limiter tiles

Bare POCO AXF-5Q graphite tiles were installed as the plasma-facing surface of the Tokamak Fusion Test Reactor (TFTR) movable limiter for a series of ∼2700 high power discharges (600 with up to 6 MW neutral beams). During this operating phase, erosion and deposition processes modified the surface of the limiter. In the regions of the most intense plasma contact, which reached temperatures over 2400 °C, only small amounts of metallic impurities (&amp;lt;5×1016 atoms/cm2) are observed during subsequent beta backscattering and proton-induced x-ray emission (PIXE) analysis. Also observed in these regions are several small areas of surface crazing, and scattered droplets of metals (∼1 mm diam) presumed to originate from melted internal hardware. In regions more removed from direct plasma contact, thicker metallic deposits are observed (∼2×1018 atoms/cm2). There are more of these deposits on the side facing the electron drift direction than on the ion drift side. The metallic deposits are composed of ∼55% Ni, 25% Cr, and 20% Fe and several trace elements. Near-surface retained deuterium levels vary from 1016 to 1018/cm2 along one ion-side/electron-side pair of tiles. Deuterium from TFTR operations in the bulk of a tile may have been as much as 5 ppm. Hydrogen in the tile was ∼1 at. %. Surface roughness measured outside the intense plasma contact region is much more than the original POCO AXF-5Q graphite, whereas within the plasma contact region, tile surfaces are somewhat smoother than they were initially. Two of the tiles in high heat flux regions broke during operation. The resulting geometry change led to areas of enhanced erosion and nearby redeposition of carbon.

The use of stable isotopes in the study of photosynthesis in freshwater plants

The ratio of 13C/ 12C for photosynthetic tissues of 22 aquatic species was unrelated to photosynthetic pathway. In three aquatic environments CAM and non-CAM species were shown to have similar δ 13C values. Although these CAM species derive up to half of their net carbon gain through dark fixation their δ 13C values are similar to associated non-CAM species in part because the carbon source for dark CO 2 uptake is CO 2 released, through respiration or decomposition, from organic carbon. Thus, the carbon source for CAM reflects previous isotope discrimination events. As carbon isotopes are not able to distinguish the photosynthetic pathway, there is good evidence that they may prove invaluable in the study of diffusional resistance to photosynthesis. Such evaluations require careful analysis of the photosynthetic pathway, carbon species utilized and δ 13C value of the source carbon. Although stable carbon isotope values do not allow differentiation between CAM and non-CAM aquatic species, there is evidence that hydrogen isotopes may be able to distinguish these two groups. Aquatic CAM species were shown to accumulate greater levels of deuterium than associated non-CAM species.

A simple, inexpensive method of determining total body water using a tracer dose of D2O and infrared absorption of biological fluids

An improved infrared spectrophotometric method using tracer doses of D2O for determination of total body water (TBW) is described. Evaluation of sample preparation procedures showed that only vacuum sublimation yielded acceptable recoveries of D2O standards in the range of 0.01-0.30 mg/ml in urine and plasma (101 +/- 2.5 and 99.6 +/- 2.6%, mean +/- SD, respectively). Oral administration of a 10 g dose of D2O was shown to equilibrate within 2 hr in the saliva and plasma of 10 healthy men and women, including obese (30% body fat) subjects. Calculated TBW was 39.1 +/- 6.4 L which represented 74 +/- 1.6% of the fat free mass determined by hydrodensitometry. The precision of the described infrared method was 2.5%. Based upon the observed sensitivity of this method, it would be possible to administer smaller oral D2O doses, 5-6 g, and obtain reliable TBW values. The practical advantages of this method are low cost and a simple analysis that permits repeated TBW measurements over brief periods without an undue buildup of background deuterium levels in the body.

The deuteration of the histones of physarum polycephalum as a step towards the preparation of selectively deuterated nucleosome core particles

AbstractPhysarum polycephalum can be grown in shake flask culture where all of the peptone component of the feed stock has been replaced by a deuterated algal hydrolysate. These conditions give approximately 35% overall deuterium incorporation into the basic nuclear proteins. This level of incorporation, together with the maintenance of a reasonable maximum growth, show P. polycephalum to be a convenient system for the preparation of nucleosome core particles with selectively deuterated histones. Selectively deuterated core particles offer considerable advantages over uniformly protonated ones when structural studies using neutron scattering are carried out.A combination of proton and deuterium magnetic resonance spectroscopy shows that under the conditions so far studied the deuterium incorporation is not uniformly distributed throughout the amino acid residues of the proteins. A 60% deuteration of the terminal apolar methyl groups is accompanied by only 28% deuteration of the hydrogen atoms bound to the α‐carbon.Our observation that α‐carbon hydrogens are exchanged in vitro reactions with 2H3O+, albeit at elevated temperature, could well indicate these hydrogens are exchanged in vivo with the solvent water of the growth medium. Suggestions are made as to other possible variations in feed stock components which could lead to a higher overall levelof deuterium incorporation.Deuteration ‐ Physarum polycephalum ‐ neutron scattering ‐ histones ‐ nucleosome core particles.

Thermal cracking of indan in deuterium at 8 MPa pressure

The thermal cracking of indan, at 500 and 515 °C in an atmosphere of pressurized deuterium of 8 MPa, produces several cracking products, each of which consists of a mixture of isotopically-substituted molecules with various numbers of deuterium atoms. The yield of the deuterated components increases with the reaction time; the products formed at reaction times close to zero contain no or only low levels of deuterium. The deuterium in the reaction products results from a stepwise hydrogen-deuterium exchange, which occurs preferentially at naphthenic carbon atoms. In the cracking reactions of indan, which proceed by α- and β-ring opening mechanisms, indan itself functions as a hydrogen donor substance which splits off the hydrogen atoms required in the initiation of the α-ring opening and which quenches radical intermediates by intermolecular hydrogen transfer. Radical quenching with deuterium gas is a much slower reaction and accounts for <25% of the primary products formed. Taken with conclusions from previous work, the present findings indicate that the thermal hydrocracking of indan might shift from the α- or β-ring opening mechanism with direct radical -H 2 interactions towards a H-donor mechanism where radical intermediates are quenched by H-transfer from indan. This shift would be caused by increasing the concentration of indan in the system.

Measurement of the excitation transfer rate between the n = 4 levels of hydrogen and deuterium

In a hydrogen-deuterium plasma of high purity the excitation transfer rate K DH 4 for the process H ∗(n = 4) + D(n = 1)→ H(n = 1) + D ∗(n = 4) ( n is the principal quantum number) has been measured by means of dye-laser fluorescence. Using an adequate numerical model, also the corresponding cross section σ DH 4 could be determined.

The depth distribution of displacement damage in α-iron under “triple beam” ion irradiation

The depth dependence of the defect structures was determined for iron irradiated at 850 K with 4 MeV Fe ++ and energetic helium and deuterium ions to 10 dpa and fusion levels of helium and deuterium. From the damage profiles, a sectioning depth of 0.9 μm was selected for studies of iron and bcc iron alloys, such as ferritic steels, utilizing similar irradiation parameters. A comparison of the experimental damage profile to the deposited energy and deposited ion profiles calculated by the E-DEP-1 code indicated a possible overestimate of the LSS stopping power of at least 22%.

Deuterium NMR evaluation of the positional distribution of low levels of deuterium in the presence of Eu(fod)3

Deuterium NMR evaluation of the positional distribution of low levels of deuterium in the presence of Eu(fod)3

High-temperature phase transition in RbH2PO4, KD2PO4 and KH2AsO4

The high-temperature phase transition in single crystals of RbH2PO4 (RDP), KD2PO4 (DKDP) with different levels of deuteration, and KH2AsO4 (KDA), has been investigated by measurements of the dielectric constant, electrical conductivity and IR reflectivity, in the temperature range 300-500°K. RDP and KDP with a deuterium concentration higher than 74%, show a proper high-temperature phase transition, associated with crystalline structural change. For RDP, the transition temperature varies between 345-375°K, depending strongly on crystalline perfection, while for DKDP, the transition temperature decreases linearly from 453°K with increasing concentration of deuterium. For DKDP with a deuterium level lower than 74%, the transition temperature is constant at 453°K, and the transition is probably connected with the emission of water vapour. No transition is detected in the case of KDA.

Deuterium isotope effects in Nicotiana tabacum

The effects of increasing concentrations of heavy water (2H2O) on the growth, development, morphology, and transpiration patterns in Nicotiana tabacum L. were studied throughout the life cycle of the plant. The higher deuterium levels caused a marked reduction in size and flowering, together with extensive tissue necrosis. These observations are consistent with the literature on the effects of deuterium on plant development. The present study showed a deleterious effect of deuterium on alkaloid production, associated with heightened transpiration rates and decreased fractionation of carbon isotopes in photosynthesis. All of the observed effects are consistent with the established view of deuterium as a nonspecific chaotropic agent, whose effects are evident at every level of plant organization.

The analysis of deuterium content of hydrogen at and below natural abundance levels

Some simple modifications to a small commercial mass spectrometer are described which enable HD/H 2 isotope ratios to be determined in hydrogen streams with a standard deviation of 2.9 p.p.m. at the 95% confidence level. Differences in isotope ratios between feed and processed hydrogen streams were determined with a standard deviation of 2.3 p.p.m. The system has been used to determine both absolute ratios and enrichment values from about 10 p.p.m. up to natural abundance levels of deuterium in hydrogen.