High Temperature Fraction Research Articles

Discharge Analysis of EAST H-Mode for Designing Compressed Plasma

Some electric parameters of Experimental Advanced Superconducting Tokamak shot #41195 are analyzed out for compressed plasma at its flat-top phase—the phase has 32-s stationary H-mode plasma discharge and the pulse is long enough for accommodating the compression process. A good knowledge of the total plasma inductance is benefit to map the discharging evolution of vertical magnetic field judged by Maxwell equations, whose nonlinear component is to analyze the effect of noninductive current drive, including the effect of bootstrap current. Furthermore, the relationship of vertical magnetic field and line-averaged density is derived and validated during flat-top phase for given plasma current. An increase in magnetic strength of vertical field will allow high temperature, high density, high beta, and high bootstrap current fraction to be achieved, offering an attractive regime for compressed plasma to approach the Lawson parameter.

Characterization of γ-irradiated polychlorotrifluoroethylene by thermomechanical spectrometry

Three topological blocks (low- and high-temperature amorphous and crystalline) have been detected for the first time in polychlorotrifluoroethylene with a pseudo-network structure. The molecular weight of the polymer decreases and the crystalline and high-temperature amorphous fractions degrade with an increase in γ-radiation dose. Thermal annealing at 493 K leads to amorphization of the polymer, as well as its radiolysis. However, slow recrystallization of the thermally annealed polymer has been observed during storage at 300 K.

Charcoal and mollusc shell 14 C-dating of the Dunaszekcső loess record, Hungary

Abstract Accelerator mass spectrometry (AMS) radiocarbon dating of charcoals and 10 mollusc species (+2 identified at the family level) yield 64 new ages from the Dunaszekcső loess record, Hungary. Charcoal 14 C ages are found to be protocol-dependent, with ages obtained from the high temperature (800 °C) fraction of the two-step combustion (TSC) protocol being always the oldest and likely most reliable. One step combustion (OSC) at 1000 °C produces comparable ages with those obtained from the low temperature (400 °C) fraction of the TSC protocol. Discrepancies between the ABA-TSC 400 and TSC 800 ages become larger for older, and less well-preserved charcoal fragments. Testing of shell ages against those of charcoals reveals that Succineidae sp. , Chondrula tridens , Trochulus hispidus and members of the family Clausiliidae yield 14 C ages that are statistically indistinguishable from charcoals recovered from the same stratigraphic interval, or with the ABA-TSC 800 charcoal age. Thus, these species show great potential for creating accurate and precise chronologies for loess records within the useful range ( 14 C-dating of land snails. Conservative estimates of 95% uncertainties of the resulting Bayesian age-depth models are in the range of 500–800 yr. However, these uncertainties are strongly dependent on the number of dates available and the resolution of sampling, but they are usually well below those of luminescence chronologies.

Thermochemical storage performances of methane reforming with carbon dioxide in tubular and semi-cavity reactors heated by a solar dish system

Thermochemical storage performances of methane reforming with carbon dioxide in tubular and semi-cavity reactor heated by a solar dish system have been experimentally and numerically investigated. The methane conversion and thermochemical storage efficiency of methane reforming process in tubular reactor were experimentally studied for inlet flow rate 3–6L/min and direct normal irradiation (DNI) 677.8–714.3W/m2. According to the experimental system and results, Gaussian distribution model is derived for concentrated solar energy flux from solar dish, and a 3D finite volume method coupled with volumetric reaction kinetics and unilateral concentrated solar energy flux is established by experimental verification. The simulated methane conversion and energy storage efficiency have good agreements with the experimental data, and the temperature and species concentration distributions of the reactor are also successfully predicted. In the middle region of reactor, the concentrated solar energy flux and heat loss reach maxima, while the net heat flux and reaction kinetic rate reach maxima in the front region because of high temperature and high reactant fraction. As the catalyst bed length increases, the residence time and reverse reaction rate both rise, so there exists a proper catalyst bed length. When DNI rises, the methane reforming is promoted, while the heat loss remarkably increases, which results in the maximum thermochemical storage efficiency under proper DNI. Structural and operating parameters for the present tubular reactor can be further optimized, and the proper catalyst bed length is 300mm, while the proper DNI is 250–300W/m2 (focal energy flux of 244.3–293.2kW/m2). A semi-cavity reactor is designed to reduce the heat loss and enhance the energy storage performance. According to the experimental results under inlet flow rate 2–6L/min and DNI 452.4–598.5W/m2, the methane conversion of semi-cavity reactor can be increased to 74.8%, and the thermochemical storage efficiency and total energy efficiency can be respectively increased to 19.7% and 28.9%.

MAS NMR study of the solidified cryolite systems with FeO addition

Unexpected results were obtained during investigation of the chemical processes between cryolite (Na3AlF6) and FeO by multinuclear 27Al, 23Na and 19F MAS NMR spectroscopy in the system with different amount of FeO; (1−x)Na3AlF6–xFeO (x=0.00, 0.05, 0.10, 0.14). Surprisingly, no reactions products are present in solidified fractions of samples after melting. NMR data of all the bulks proved the presence only of non-reacted cryolite and NaF, which is the product of known partial cryolite dissociation reaction. No FeO containing phases or other phases containing iron are present in the bulk of analyzed samples. On other hand all reaction products were identified in the condensed vapours that escape from the melts at reaction conditions. Two volatile (high temperature and low temperature) fractions were separated. In the high temperature condensate the presence of AlF3, Na5Al3F14, cryolite and Al2O3 was evidenced. The presence of AlF3 and Na5Al3F14 phases arises from decomposition of the vaporized NaAlF4 phase. The presence of Na3AlF6 and Al2O3 in condensed high temperature vapours seems to be ground-breaking result. The presence of these two phases was explained by the sequence of processes when at the beginning FeO was dissolved in cryolite, then oxygen was bounded to aluminium forming some fluorido-oxido-aluminates that are volatiles and during condensation they decompose to Na3AlF6 and Al2O3. Phases with remaining iron were identified in the low temperature condensed vapours.

Low-Temperature and Temperature Stepped-Combustion of Terrace Sediments from Nanfu, Taiwan

We discuss a radiocarbon study of sediment samples collected from Nanfu terrace in western Taiwan. From these, we extracted humic acids (HA) and humin from the very fine and coarse grain-size fractions using a standard acid-alkali-acid pretreatment. The humin extracts were combusted at 400 and 1100 °C by stepped-combustion, to yield a low-temperature (LT) carbon component and a high-temperature (HT) carbon component. We compare the ages of the LT and HT humin fractions to the HA fractions, in samples collected at 2 depths within the Nanfu terrace. As in previous stepped-combustion studies on sediments, we find that the HA ages are the youngest on average, and overlap the LT ages, and that the carbon contained in the HT fraction is always distinctly older than the LT and HA ages. To better understand the relationship between 14C age and combustion temperature, we conducted an incremental stepped-combustion experiment with one of the samples (1E) using 50 °C steps that ranged from 300 to 1100 °C. The 14C results of the stepped-combustion products show a clear division between 2 isotopically identifiable carbon constituents, from carbon released below 400 °C and carbon released above 550 °C. By comparing the δ13C and 14C results, we find evidence for a third carbon isotopic component in the humin that is released when combusted at ∼500 °C.

Production of anomalous Xe in nanodiamond in chondrites during the last supernova explosion predating the origin of the Solar System

Anomalous Xe enriched in both heavy and light isotopes (Xe-HL) was identified in the high-temperature Xe fraction in relict nanodiamond grains from chondrites, whereas the low-temperature Xe fraction (Xe-P3) typically has the normal isotopic composition. The paper presents a concise review of current models put forth to account for the genesis of nanodiamond with anomalous noble gas components and specifies a real process and major regularities during the generation of the isotopic relations of the anomalous Xe-HL component in relict nanodiamond grains. This component is demonstrated to be formed and captured simultaneously with the synthesis of nanodiamond, when shock waves induced by supernova explosions propagated. It is important that diamond synthesis during the passage of shock waves and the enrichment of this diamond in Xe-HL are also possible in the wave forefront region under extremal P-T conditions, in the pressure drop region behind the wave front (by means of nucleation), and by means of irradiation of carbonic grains with high-energy particles. The isotopic composition of Xe-HL results from an increase in the hardness of the spectrum of nuclear-active particles and its enrichment in heavy ions at acceleration in shock waves. Arguments are presented in support of the hypothesis that the nanodiamond population found in chondrites was produced during the latest supernova explosion before the development of the Solar System, with the supernova likely being a SnIa carbon detonation supernova. This furnishes evidence in support of recently advanced hypotheses that the nanodiamond population of chondrites is not presolar.

Characterization of the Microstructure of Bimodal HDPE Resin

In this work, two industrial bimodal high density polyethylene resins, resin A and resin B, having similar molecular weight (Mw), molecular weight distribution (MWD, and short-chain branching (SCB) content but different mechanical properties, were fractionated through cross-fractionation. The fractions were further characterized by GPC, 13C NMR, DSC and FT-IR techniques. These two resins were firstly fractionated into two fractions, i.e., high-temperature and low-temperature fractions, via preparative solution crystallization fractionation. Resin A with much better mechanical properties contains more high-temperature fractions with longer crystallizable sequences. The SCB content in the low-temperature fraction of resin A is lower than that of resin B. Both low-temperature fractions were then further fractionated using solvent gradient fractionation (SGF). The characterization of SGF fractions indicates that most of the branches fall into the high molecular weight chains in both low-temperature fractions. However, the high molecular weight chains in the low-temperature fraction of resin A contain less SCB than that of resin B.

Electrochemical modeling of hydrogen production by proton-conducting solid oxide steam electrolyzer

An electrochemical model was developed to study the J–V characteristics of a solid oxide steam electrolyzer based on proton-conducting electrolyte (H-SOSE) for hydrogen production. All important overpotentials, namely, activation, concentration, and ohmic overpotentials, were considered in the model. The model was validated as the simulation results agreed well with experimental data from literature. It was found that the optimal designs of H-SOSE and conventional SOSE based on oxygen ion-conducting electrolyte (O-SOSE) are totally different. For conventional O-SOSE, the anode-supported configuration has been identified as the most favorable design for high energy conversion efficiency. However, in the present study, it was found that the cathode-supported configuration was the most favorable design for H-SOSE. The electrochemical performance of the H-SOSE can be further enhanced by operating the cell at high temperature or high steam molar fraction. The electrochemical modeling analyses provide a better understanding of the working principles of H-SOSE and can serve as an effective tool for design optimization.

Spectroscopic ellipsometry investigations of the thermally induced first-order transition ofRbMn[Fe(CN)6]

We report on detailed spectroscopic ellipsometry investigations on the thermally induced first-order phase transition of rubidium manganese hexacyano-ferrate $(\text{RbMn}[\text{Fe}{(\text{CN})}_{6}])$ pellet sample. This switchable solid shows a cooperative Jahn-Teller distortion coupled with a local charge transfer between Fe and Mn ions. Optical spectra of the real, ${\ensuremath{\epsilon}}^{\ensuremath{'}}$, and imaginary, ${\ensuremath{\epsilon}}^{\ensuremath{''}}$, parts of the complex dielectric constant have been recorded in the interval of temperature, i.e., 250\char21{}350 K, around the transition region and in the optical range of 190\char21{}830 nm. Four (two) optical bands have been identified and assigned in the low-temperature (high-temperature) phase, corresponding to the ${\text{Fe}}^{\text{II}}{\text{-CN-Mn}}^{\text{III}}$ $({\text{Fe}}^{\text{III}}{\text{-CN-Mn}}^{\text{II}})$ state. We performed a quantitative analysis by fitting our spectra with Gauss-Lorentz (GL) line shapes and determined the energy positions, oscillator strengths, and widths of individual transitions, as well as their thermal variation. It has been found that the GL profiles excellently approximate the optical response. Moreover, we observed a significant shift of the metal-ligand charge-transfer band8 upon the thermal transition and correlated it quantitatively to the volume change at the transition. We then derived the coefficient of the volumetric thermal expansion of the title compound and found $\ensuremath{\alpha}=(\ensuremath{\partial}V/\ensuremath{\partial}T)/\overline{V}\ensuremath{\simeq}3.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }{\text{K}}^{\ensuremath{-}1}$ in the transition region and ${\ensuremath{\alpha}}_{T}^{LT}\ensuremath{\simeq}4.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }{\text{K}}^{\ensuremath{-}1}$ $({\ensuremath{\alpha}}_{T}^{HT}=8.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }{\text{K}}^{\ensuremath{-}1})$ in the low-temperature (high-temperature) region, in very good agreement with the reported zero thermal-expansion character of this compound. Finally, from the analysis of the integrated absorption spectra, we derived the thermal hysteresis of the high-temperature fraction, which was found in very good agreement with that of magnetic data recorded on the same sample.

Micro-Fourier Transform Infrared (FT-IR) and δD value investigation of hydrothermal vein quartz: Interpretation of fluid inclusion δD values in hydrothermal systems

Some recent studies have suggested that the hydrogen isotopic composition ( δD) of hydrothermal fluids, released in vacuo by thermal decrepitation of quartz, are not always accurately revealed. We report the results of a step-heating δD value study of vein quartz, hosted by Lower Palaeozoic rocks in SW England, which was analyzed by micro-FT-IR for hydrogen speciation, before and after fluid extraction at temperatures between 750 and 1500 °C. The δD values of individual aliquots of released water vary between −3‰ and −208‰, with the lowest values generally corresponding to the highest temperature fractions and samples of relatively low yield. The data show significant departures from geologically reasonable δD. Micro-FT-IR analyses show that a variety of OH species are present within the vein quartz, with significant intra and inter sample variation. Typically a broad absorption due to molecular water, in the region 3400 cm −1 is observed, along with bands attributed to Li–OH and Al–OH. On heating, the broad absorption due to molecular water is reduced, accompanied by a measurable loss of Li–OH species. The latter becomes more pronounced in the higher temperature fractions (>750 °C). These data support earlier studies which indicated that contributions from the contrasting OH reservoirs in quartz can significantly influence the reported δD values. These new data also suggest that the incorporation of OH released from Li–OH sites in the quartz may be the most important factor in the generation of the anomalous values for these samples.

Aeration of low fat dairy emulsions: Effects of saturated–unsaturated triglycerides

Three dairy emulsions containing 10 wt% anhydrous milk fat (AMF), alone or in mixture with its low or high melting temperature fraction (olein- or stearin-rich fraction, respectively), were aged at 4 °C for 24 h and then submitted to a whipping test at this temperature. We observed that the AMF/olein emulsion presented less crystalline fat content, and a higher ability for air incorporation than the other two emulsions. In addition, air bubbles formed in the AMF/olein-rich emulsion presented a more uniform size distribution, a smaller proportion of bubbles higher than 50 μm, and they appeared to be coated with a thicker layer of fat droplets. These results indicated that foam-structure forming properties in reduced milk fat emulsions can be enhanced by lowering the proportion of saturated triglycerides.

Studies on the density profiles of square-well chain fluid confined in a slit pore by density functional theory

The density profiles of square-well chain fluid confined in two planar walls are calculated using density-functional theory based on the weighted-density appro ximation of Yethiraj. The free energy functional of the system consists of an id eal part and excess part. We obtain the excess part by the equation of state of corresponding uniform system combined with the weighted-density approximation. We adopted respectively the equations of state based on cavity correlation fun ction and the statistically associating fluid theory. The calculated density pro files are compared with the corresponding Monte Carlo simulation data at differe nt chain lengths, temperatures, volume fractions and different attractions of t he wall. For a square-well chain fluid confined in two hard planar walls, result s from both equations of state are in good agreement with that of the Monte Car lo simulations at high temperature and high volume fraction. Both results devia te from the Monte Carlo result at low temperature and low volume fraction. The density profile in hard wall slit pore calculated from the equation of state of SAFT-VR is in better agreement with the available simulation data than that fro m the equation of state developed by Liu et al. We find that the equation of st ate has significant influence on theoretical prediction. For the walls with attr active forces, predictions from both equations of state deviate from the simula tion data. This deviation results from the increasing non-uniformity of the flu ids. Therefore, more suitable weighted-density function is needed to improve the density-functional theory.

Effect of copolymerized ethylene unit on the crystallization behavior of poly(propylene-co-ethylene)s

The crystallization behavior of two kinds of commercial poly(propylene-co-ethylene)s (PPE1, PPE2) with similar average molecular weight and molecular weight distribution, isotacticity and copolymerized ethylene unit content and their fractions was investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and polarized optical microscopy (POM) techniques. The results indicate that the PPE1 isothermally crystallized films possess thicker and less cross-hatched lamellar structure than those of the PPE2. As for the fractionated samples, the thin films of low temperature (≤90°C) fractions (PPE1-80, PPE2-80) of both PPE1 and PPE2 exhibit similar crystallization behavior, while for the high temperature (≥95°C) fractions (PPE1-108, PPE2-108), the crystalline morphology has marked differences. Compared with PPE2-108, the PPE1-108 isothermally crystallized thin films possess thicker lamellae and less cross-hatched lamellar structure, while for the fibrous crystal number, the former is less than that of the latter. The main reason to create the crystallization behavior differences between the two PPEs and their fractions is due to the effect of molecular chain structure, i.e. the different distribution of copolymerized ethylene unit in polypropylene chains.

Stepped-Combustion 14C Dating of Bomb Carbon in Lake Sediment

In this study, we applied a stepped-combustion approach to dating post-bomb lake sediment from north-central Mississippi. Samples were combusted at a low temperature (400 °) and then at 900 °. The CO2 was collected separately for both combustions and analyzed. The goal of this work was to develop a methodology to improve the accuracy of 14C dating of sediment by combusting at a lower temperature and reducing the amount of reworked carbon bound to clay minerals in the sample material. The 14C fraction modern results for the low and high temperature fractions of these sediments were compared with well-defined 137Cs determinations made on sediment taken from the same cores. Comparison of “bomb curves” for 14C and 137Cs indicate that low temperature combustion of sediment improved the accuracy of 14C dating of the sediment. However, fraction modern results for the low temperature fractions were depressed compared to atmospheric values for the same time frame, possibly the result of carbon mixing and the low sedimentation rate in the lake system.

Relationship between submarine MORB glass textures and atmospheric component of MORBs

We investigated the relationship between noble gas signatures and sample textures among glassy fragments. Glassy MORB fragments were classified based on their texture. By handpicking under a binocular, they were divided into three groups: (1) heterogeneous “outer” part, (2) homogeneous “middle” part, and (3) “inner” neighbors of the transition zone. Their noble gas signatures were analyzed by the step heating method. The state of homogeneities of the samples identified under a microscope was confirmed semi-quantitatively by measuring refractive indices of the fragments. The “outer” heterogeneous part characterized by devitrified and/or color changed regions was significantly affected by the atmospheric component as indicated by the relatively large amount of gases released with almost atmospheric 40Ar/ 36Ar and 20Ne/ 22Ne in the 400 °C fraction. The transition “inner” part of glassy rind adjacent to the crystallized interior which is characterized by the appearance of quenched microcrystals has lost the magma-derived component and is contaminated by some kinetic processes: it showed a small amount of noble gases except for Ne with a low 20Ne/ 22Ne ratio. The homogeneous “middle” part turns out to be least affected by contamination and is regarded to mostly retain magma-derived noble gas signatures. It is characterized by the most abundant He and the highest 40Ar/ 36Ar as a total ratio with similar values in both the middle and the high temperature fractions. This part is also characterized by lower refractive index values and a small deviation compared to the nonhomogeneous parts. Hence, for noble gas analyses of MORB glasses, it is recommended to select homogeneous “clear” glasses by excluding color changed and/or devitrified weathering part and quenched microcrystals.

High-speed liquid chromatography by simultaneous optimization of temperature and eluent composition.

Clearly, a major trend in liquid chromatography is to increase its speed to make it faster. Improving throughput for routine analysis of pharmaceutical release samples and stability assays are all key motivations for improving separation speed. Recent work has focused on the theoretical benefits of temperature on speed in liquid chromatography. We have shown that the 5-10-fold decrease in eluent viscosity that comes from a temperature increase of 175 degrees C over ambient, and the concomitant increase in analyte diffusitivity, act to dramatically decrease the time needed to generate a theoretical plate. Lower viscosities at elevated temperatures decrease the pressure drop across the column and allow the use of higher linear velocities as the pump pressure limit is approached. Simultaneously, faster analyte diffusion at higher column temperature improves efficiency at high eluent velocity conditions compared to the efficiency at lower temperatures at the same velocity. We find that higher temperature plays a central role in improving speed. In this work, we show that when the percent organic modifier in the eluent and column temperature are adjusted to keep retention factors fixed, highly efficient, subminute separations can be routinely achieved when a hot column is used at the maximum system back pressure. We find that the best way to facilitate such an optimization, assuming constant selectivity, is to use a very retentive column so that one can work at both high temperature and high volume fraction of organic modifier to achieve the lowest possible eluent viscosity. We have also analyzed the effect that key extracolumn contributions have on column selection and system design.

Radiocarbon dating of bone apatite by step heating

Summary and Analysis The choice of pretreatment methods is critical to the success of the step heatingmethod as dating results varied widely depending upon the pretreatment used. Theuse of an acetic acid wash followed by a NaOCl/acetic acid wash gave the bestresults. Performing solution transfers under a nitrogen atmosphere may have im-proved dates as well, but more likely the success of Dent series 4 is due to the useof tooth enamel. The success of the dates from Murray Springs supports this con-tention as solution transfers were not performed under nitrogen. All of the seriesgenerally showed a trend of increasing age with increased extraction temperature.The lowest temperature fraction consistently produced the youngest dates and inthree series (e.g., Dent series 2 and 4, Murray Springs) were significantly offsetfrom the general trend of the other samples. This suggests that perhaps CO 2 re-leased at very low temperatures ( 500 C) is derived in part from a highly ex-changeable fraction of carbonate, perhaps that absorbed to crystal surfaces aspostulated by Hedges et al. (1995:289).The general patterning seen in the Dent data suggests a system composed of aseries of carbonate fractions that vary in their susceptibility to exchange, with noparticular temperature fraction being totally immune. A simple model shows howtemperature-age spectra may evolve with increased contamination (Figure 3). Themodel shows five temperature fractions, each being less susceptible to exchangethan the previous lower temperature fraction. As a bone becomes increasinglycontaminated, the slope of temperature-age spectra becomes increasingly steep.This occurs because low temperature fractions, being more susceptible to ex-change, are contaminated at a greater rate than high temperature fractions. If sucha model is accurate, it provides a convenient means of estimating the amount ofcontamination affecting a sample based on shape of the temperature-age spectrumproduced. Spectra with a steep slope tend to produce

The Fatty Acid Composition of Phosphatidylglycerol and Sulfoquinovosyldiacylglycerol of Zea mays Genotypes Differing in Chilling Susceptibility

Summary The content and fatty acid composition of four major chloroplast lipids, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylglycerol and sulfoquinovosyldiacylglycerol, have been measured in the intact leaves of maize inbred lines differing in chilling susceptibility. Visual assessment of chilling injury symptoms during post-chilling recovery of seedlings indicated that both lines CM 7 and Co 151 were more chilling susceptible than lines S 215 and EP l, exhibiting greater chilling tolerance. Fatty acid composition of chloroplast polar lipids was very similar and some small deviation in the content of individual fatty acids did not affect uniformity of the general pattern. In all four lines of maize the content of height-temperature melting fraction of phosphatidylglycerol (htm-PG) and double bond index of polar lipids were equal, while fatty acid composition of polar lipids was very similar despite of small deviations in the content of individual fatty acid. Although the level of the high-temperature melting fraction of sulfoquinovosyldiacylglycerol (htm-SQDG) was lower in CS and CT lines Co 151 and S 215, respectively, than in CS and CT lines CM 7 and EP 1, respectively, this difference could not be related to their chilling sensitivity. All of these data do not support the concepts that the level of htm-PG alone or in combination with low-temperature-melting lipid would differentiate the chilling sensitivity of maize inbred lines. It is likely that some other factors are responsible for differential injury symptoms observed in chilled maize seedlings upon recovery. Discrepancies between the level of htm-PG and chilling sensitivity in several other species as well as various effects of acclimation on the level of htm-PG and temperature of phase transition are discussed.

Mantle-derived noble gases in carbonatites

Isotopic compositions of the noble gases (He, Ne, Ar, Kr, Xe) were obtained by stepwise heating of separated mineral phases from carbonatites from Brazil (Jacupiranga, Tapira) and Canada (Borden, Oka, and Prairie Lake) as well as one syenite (Poohbah Lake, Canada). Mineral phases used were apatite, forsterite, diopside, calcite, monticellite, and perovskite. Large amount of in situ produced 238U-fissiogenic 131–136Xe, along with lesser amounts of 238U-fissio-genic 83–86Kr and in situ 4He were found in most samples. An apatite sample from the Prairie Lake carbonatite showed a 136 Xe 130 Xe ratio of about 1400. Some samples, mostly apatites, showed excess 129Xe relative to air in the high temperature (1800°C) gas fractions. The highest 129 Xe 130 Xe ratios, between 7.0 and 8.6, are similar to those found in other mantle-derived materials such as MORBs and diamonds. The excess `Xe is considered to be primordial and attributed to now extinct nuclide 129I once present in the early history of the Earth. Neon isotopic compositions were also anomalous showing very low 20 Ne 22 Ne ratios (down to 0.01) and high 21 Ne 22 Ne ratios (up to 1.25). They are attributed to Wetherill reactions, such as 18O(α, n) 21Ne, 19F(α, n) 22Na( β +) 22Ne, and so on. The measured 40Ar/ 36Ar ratios are extremely variable and range from values that are close to atmospheric to values as high as 42400. Stepwise heating studies of an apatite from the Jacupiranga carbonatite indicate that the high temperature fractions retain the original noble gas signature of the carbonatite source. The 40Ar/ 36Ar ratios for the high temperature gas fractions are about 6400 or smaller. A plot of 40Ar/ 36Ar vs. 129Xe/ 130Xe shows that the source of carbonatites is different and less degassed than that of MORBs. The presence of excess 129Xe in carbonatites suggests that carbon in carbonatites is unlikely to be recycled C related to subduction processes.