Low-temperature Fractionation Research Articles

Flavour Components of Whiskey. I. Distribution and Recovery of Compounds by Fractional Vacuum Distillation

A vacuum fractional distillation procedure is described for separating both the matrix components and flavour compounds of a whiskey into well-defined groups based on differences in azeotropic boiling points. The distillation was carried out at near ambient temperatures to accommodate both unaged and aged whiskies. Analytical and sensory data indicated good recovery of congeners. Individual fractions were reconstituted with ethanol and water to the original volume and strength dimensions of the whiskey. Undesirable thermal changes in the aged products were minimised by the low temperature fractionation and allowed changes in the flavour composition of whiskey due to maturation to be investigated for such unaged and aged reconstituted pairs.

The tectonomagmatic significance of Neoarchaean variably alkali-enriched gabbro and diorite intrusions of the western Karelia Province

Abstract This study describes a group of Neoarchaean alkali enriched gabbros and diorites from the western Karelia Province of the Fennoscandian Shield. We provide new field observations, petrography, whole-rock chemical data and additional whole-rock Sm–Nd and O-isotope data from these Neoarchean rocks. Compositionally, the rocks can be classified as shoshonitic with elevated rare earth element, K 2 O, Ba and Sr contents together with variable MgO, Ni and Cr contents. The MgO, Ni and Cr depletion observed especially in one of the intrusions could have been caused by fractionation of olivine and clinopyroxene from the system. Zircon O-isotope values from one of the intrusions (δ 18 O=7.34±0.10‰) indicate the involvement of material that had undergone low-temperature fractionation of oxygen in the genesis. Samarium–Nd data imply contribution from older material in the petrogenesis of these rocks. The above-mentioned characteristics can be explained with a magma source in the mantle that was heterogeneous owing to the variable degrees of metasomatism. The alkali-enriched gabbros and diorites provide additional evidence for magmatism derived from heterogeneously enriched mantle during the Neoarchaean in the Karelia Province and associated with the cratonization of the area. Supplementary material: Table detailing oxygen-isotope analyses from this study is available at https://doi.org/10.6084/m9.figshare.c.3466575

Effect of various surfactants on the stability time of kerosene–boron nanofluids

Nanofluid fuels, a new class of nanotechnology-based fluids, are liquid fuels with a stable suspension of nanometre-sized particles. The preparation of fuel mixtures and achieving to a stable and long-term suspension is the key step in nanofluid synthesis. The idea of this work is to suspend nano- and micron-sized boron particles in kerosene, exploring the differences between the complete sedimentation times of particles in fuel at various weight fractions of surfactants and investigating the viscosity of nanofluid at low weight concentration of nanoparticles. Various surfactants including oleic acid, propylene glycol, sorbitan oleate, Tween 85 and CTAB were used to prepare stable kerosene/boron slurries. Suspensions were prepared with varying surfactant loadings of 0.1–2.0% by weight, in steps, for the same particle loading of 0.5 wt%. The results showed that sorbitan oleate was the best surfactant and the optimum weight ratio of boron particle to sorbitan oleate for enhanced stability of nanofluid was determined to be 2. The complete sedimentation time of nanoparticles at the most stable nanofluid was ∼57 h. At low temperature and high weight fraction of particles, nanofluids showed similar 67% enhancement in viscosity properties.

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.

Analysis of the Possibility of Using Industrial Low-Temperature Fractionation for 3He/4He Separation

Analysis of the Possibility of Using Industrial Low-Temperature Fractionation for 3He/4He Separation

Monte Carlo simulation study of the halogenated MIL-47(V) frameworks: influence of functionalization on H2S adsorption and separation properties

Monte Carlo simulation calculations were performed to explore the H2S adsorption and separation in the initial MIL-47(V) and the monohalogenated MIL-47(V)-X (X = F, Cl, Br). Both initial and halogenated MIL-47(V) metal–organic framework materials (MOFs) exhibit an ultra-high H2S adsorption ability, which is much higher than that of CH4 and N2. Halogen functionalization could enhance the H2S uptake in unit volume of MOFs especially in low-pressure range, with the sequence: MIL-47(V) MIL-47(V)-F > MIL-47(V)-Cl > MIL-47(V)-Br, because of the increasing mass density of MOFs after halogenation. The adsorption behavior of four MOFs for the H2S/CH4 and H2S/N2 mixtures are explored as a function of both pressure and H2S mole fraction, and all of four MOFs show the ultraselectivity toward H2S molecule. Compared to the initial MIL-47(V), the halogenated MOFs exhibit the preferable H2S/CH4 and H2S/N2 selectivity under the conditions of low temperature, high pressure, and high H2S mole fraction.

Thermal stability of soil organic matter was affected by 23-yr maize and soybean continuous cultivation in northeast of China

Long-term continuous cropping affects the biochemical quality of soil organic matter (SOM), but whether the effects are relevant with their thermal stability is less clear. In northeast China, long-term continuous cropping occurred frequently owing to higher yield and economic interest requirement. To verify the thermal stability properties of SOM affected by the long-term continuous cropping, the study focused on 23-yr continuous cultivated maize and soybean plots, where the effect of cropping is likely to be detected. Bulk soils sampled in 1991 and 2014 were studied by thermogravimetry and differential scanning calorimetry (DSC). The results showed typical bimodal peaks in DSC curve in bulk Mollisols. A labile fraction peak was observed at 354–366 °C low-temperature zone and recalcitrant fraction one at high temperature of 430–438 °C. Energy density (J mg−1 OM) was greater in soybean plots compared to maize plots; in contrast, long-term continuous maize cultivation also increased energy density, in reverse in soybean plots after 23-yr cultivation. The DSC-T50, temperature at which half of energy release occurred, typically showed larger responses to long-term cultivation than crop species. Results obtained support the hypothesis of a potential link between long-term continuous cropping and the thermal stability of SOM, and a correlation with crop species.

Estimation of Minimal Specific Power Consumptions for Extraction of 16O18O, 18O18O, and 17O17O Type of Molecules from Natural Molecular Oxygen

The minimal specific work required for separating gaseous natural oxygen to extract 17O17O and 18O18O isotopes is calculated. A procedure is proposed for determining the composition of gaseous oxygen by analyzing its isotope composition. Also proposed is a procedure for determining the height of the column for separating 16O16O–16O18O and 16O16O–18O18O binary mixtures by low-temperature fractionation.

Xes-Xen thermochronology of the Rayner metamorphic complex, Enderby Land (East Antarctica, Molodezhnaya Station Area)

The Xes-Xen dating of zircons from rocks of the Rayner Complex of the Enderby Land at the Molodezhnaya Station area (coast of the Alasheyev Bight) yielded age estimates of 550 ± 50 and 1040 ± 30 Ma. The metamorphic rocks of the Rayner Complex record two main events: first, the crystallization of the magmatic protoliths of charnockitic and enderbitic gneisses and, second, superimposed structural and metamorphic alterations under conditions transitional from the amphibolite to granulite facies (metamorphism manifested regionally in the rocks of the Rayner Complex). The most reliable Xes-Xen age estimates for magmatic zircons from the charnockitic and enderbitic gneisses correspond to the Grenville stage of the development of the Rayner Complex (∼1.0 Ga). The Xe isotopic systematics of metamorphic zircons reflect a pan-African stage in the evolution of the Rayner Complex (600–550 Ma). Pan-African events are reflected in the U-Xe isotope system in two cases: if metamorphic zircons crystallized at the same time (which probably resulted in the formation of a plateau in the Xes-Xen age spectrum) and if the initial isotopic systems were disturbed (which resulted in a decrease in apparent age toward low-temperature gas fractions). It is important that secondary alterations and a decrease in apparent ages to 600–550 Ma affected only those components (i.e., caused xenon release only from those traps) that were unstable under the maximum metamorphic temperatures and yielded Tcl values lower than 750°C (conditions transitional from the amphibolite to granulite facies). At a higher xenon retention, “primary” isotopic systems are preserved. Consequently, the age of metamorphism transitional between the amphibolite and granulite facies can be estimated at 600–550 Ma on the basis of Xes-Xen dating. In general, the results of our study indicate that the age of regional metamorphism of the Rayner complex at the Molodezhnaya area is approximately 600–550 Ma rather than ∼1.0 Ga, as was previously supposed.

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.

Process Simulation and Parameters Optimization of Low Temperature Fractionation of CO<sub>2</sub> Capturing from EOR Natural Gas

In this paper, the model of low temperature fractionation CO2 capturing process is established with HYSYS to carry out the simulation of the process. According to the simulation results, it is concluded that as the CO2 content in the feed gas raises, the CO2 product purity increases and the cooling energy cost of the system decreases. As the CO2 product purity rises, the cooling energy cost increases more and more rapidly. According to the 91.0% CO2 content feed gas, the optimized fractionation pressure is 3.1MPa and the corresponding liquefaction temperature and condensing temperature is-20°C and-24°C respectively.

Effect of Cu doping on the electrochemical properties and structural phases of La0.8Sr0.2Mn1−xCuxO3 (0≤x≤0.2) at elevated temperature

Abstract The electrochemical properties of La 0.8 Sr 0.2 Mn 1 − x Cu x O 3 (0 ≤ x ≤ 0.2)–Gd 0.2 Ce 0.8 O 2 − δ (GDC) composite cathodes are determined in the intermediate-temperature range (600–850 °C), and their cathode performance is analyzed in the context of their phase transition behavior at elevated temperatures. The addition of Cu to LSM forces Mn 3 + to Mn 4 + , thereby increasing the Mn 4 + concentration with increasing Cu doping. The increased Mn 4 + concentration increases the cubic phase fraction, and thus enhances the low-temperature performance of the LSM cathode. The La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 –GDC yields the greatest low-temperature cubic phase fraction and shows the smallest area specific resistance (0.49 Ω cm 2 at 750 °C) of the compositions tested.

Antioxidant properties of hymatomelanic acids from brown coal

The antioxidant activity of a low-temperature fraction of hymatomelanic acids from brown coal in a model process of the radical chain oxidation of cumene was determined using a gas-volumetric method. Their antiradical activity was evaluated by spectrophotometry using a reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH). The pronounced ability of hymatomelanic acids to cause antioxidant and antiradical effects in model systems was demonstrated. It was found that the antioxidant and antiradical activities increased with the concentration of hymatomelanic acids. The determined properties of hymatomelanic acids from brown coal can be useful for technical and biomedical applications.

Characteristics of the structure and properties of low-temperature fractions recovered from the powder ultradispersed polytetrafluoroethylene by sublimation

Low-molecular fractions were recovered through sublimation of the ultradispersed powder polytetrafluoroethylene (UPTFE) under isothermal conditions and specified temperatures. The present paper describes the results of study of the fractions recovered at 50–100°C with an increment of 10°. The studies revealed that the obtained fractions were in general characterized by a film structure, a paraffin-like phase composition with different crystalline structures, and a layered packing. Films of the fraction isolated at 50°C have pores; those isolated at 60°C had fibers. The molecular structures are represented by a short chain of molecules consisting of CF2 fragments with end CFCF2 groups. The chain length increases from 5 to 15 fragments along with the increasing temperature of the fraction isolation. The beginning and the process of decomposition of fractions depend on the temperature, at which the fraction of interest was obtained.

Distribution of Radiocarbon Ages in Soil Organic Matter by Thermal Fractionation

Radiocarbon analysis is an important tool in quantifying soil organic matter (SOM) dynamics within the terrestrial carbon cycle. However, there is increasing appreciation that representing SOM as a single, homogeneous pool with a single, mean 14C concentration is inadequate. We investigate whether the differing patterns in CO2 release during ramped-temperature oxidation reflect organic matter of different ages, and hypothesize that thermally labile SOM (combusting at low temperatures) consists of younger carbon than thermally resistant organic matter. Topsoil samples under contrasting land uses (native vegetation and long-term cultivation) were selected for 14C analysis before and after acid fumigation for the removal of carbonates. Results of bulk 14C analyses showed a significant shift in 14C age from 0.944 Fm under native vegetation to 0.790 Fm under cultivation. Four to 5 “fractions” associated with different CO2-evolution regions were identified by thermal analysis and analyzed for 14C via modifications to NOSAMS' established “programmed temperature pyrolysis system,” in which discrete CO2 fractions evolved during ramped-temperature oxidation were isotopically characterized by a microwave gas ion source (GIS) continuous-flow AMS (CFAMS) system. Results showed that while acid fumigation removed soil carbonates, the treatment also significantly altered the thermograms and inferred SOM composition. While direct attribution of 14C values to individual peaks is somewhat confounded by overlapping temperature ranges for oxidation of unique populations of carbon, in general, thermally stable fractions of SOM appear to be 14C-depleted compared to thermally reactive (low temperature) fractions regardless of pretreatment.

Distribution of Radiocarbon Ages in Soil Organic Matter by Thermal Fractionation

Radiocarbon analysis is an important tool in quantifying soil organic matter (SOM) dynamics within the terrestrial carbon cycle. However, there is increasing appreciation that representing SOM as a single, homogeneous pool with a single, mean 14C concentration is inadequate. We investigate whether the differing patterns in CO2 release during ramped-temperature oxidation reflect organic matter of different ages, and hypothesize that thermally labile SOM (combusting at low temperatures) consists of younger carbon than thermally resistant organic matter. Topsoil samples under contrasting land uses (native vegetation and long-term cultivation) were selected for 14C analysis before and after acid fumigation for the removal of carbonates. Results of bulk 14C analyses showed a significant shift in 14C age from 0.944 Fm under native vegetation to 0.790 Fm under cultivation. Four to 5 “fractions” associated with different CO2-evolution regions were identified by thermal analysis and analyzed for 14C via modifications to NOSAMS' established “programmed temperature pyrolysis system,” in which discrete CO2 fractions evolved during ramped-temperature oxidation were isotopically characterized by a microwave gas ion source (GIS) continuous-flow AMS (CFAMS) system. Results showed that while acid fumigation removed soil carbonates, the treatment also significantly altered the thermograms and inferred SOM composition. While direct attribution of 14C values to individual peaks is somewhat confounded by overlapping temperature ranges for oxidation of unique populations of carbon, in general, thermally stable fractions of SOM appear to be 14C-depleted compared to thermally reactive (low temperature) fractions regardless of pretreatment.

Extrapolation of Al2O3–water nanofluid viscosity for temperatures and volume concentrations beyond the range of validity of existing correlations

The emergence of nanofluids as an attractive new class of thermal fluids, with enhanced heat transfer characteristics, rapidly stimulated their use in engineering applications. It also led to the need of an intensive experimental work to determine the thermophysical properties of nanofluids affecting heat transfer such as density, viscosity, thermal conductivity and specific heat capacity. Contradictory results were obtained by several researchers for the dependence of the nanofluid viscosity on temperature, nanoparticle diameter and nanoparticle volume concentration. In regard to these variables, a summarizing work was presented by Khanafer and Vafai (2011) who successfully presented a quite general correlation for the effective viscosity of Al2O3-water nanofluid with temperature ranging from 20 to 70 °C, nanoparticle volume concentration between 1 and 9 vol%, and nanoparticle diameter between 13 and 131 nm. The present work presents a methodology for extrapolating this correlation beyond its range of validity, as a first attempt to obtain an approximate expression to systematically evaluate the viscosity of Al2O3–water in simulation of heat transfer applications for the range of temperatures from 5 to 20 °C and nanoparticle volume fractions below 1 vol%. New experimental data was obtained for the viscosity of Al2O3–water nanofluid within this range of low temperature and volume fraction, showing good agreement with most of the corresponding extrapolation values.

Isotope fractionation in aqua-gas systems: Cl2-HCl-Cl−, Br2-HBr-Br− and H2S-S2−

We report calculated values of isotope fractionation factors between chlorine, bromine and sulphide hydrated anions and respective gaseous compounds: hydrogen chloride, hydrogen bromide, molecular chlorine and bromine and hydrogen sulphide. For the calculation of the reduced partition function ratios (β-factors) of hydrated Cl−, Br− and S2− anions, we used a model of a cluster composed of the considered ion surrounded by two shells of H2O molecules. Only the electrostatic interaction between ion and water molecules treated as electric dipoles was taken into account. The β-factors for the gaseous compounds (HCl, Cl2, HBr, Br2 and H2S) were calculated from vibrational frequencies reported by Urey and Greiff [Isotopic Exchange Equilibria, J. Am. Chem. Soc. 57, 321 (1935)] and Schauble et al. [Theoretical Estimates Equilibrium Chlorine-Isotope Fractionation, Geochim. Cosmochim. Acta 67, 3267 (2003)]. Low-temperature isotope fractionation between chlorine-hydrated anion and hydrogen chloride attains 1.55–1.68‰ (this work), which is in good agreement with experimental data (1.4–1.8‰) [Z.D. Sharp, J.D. Barnes, T.P. Fischer and M. Halick, An Experimental Determination of Chlorine Isotope Fractionation in Acid Systems and Applications to Volcanic Fumaroles, Geochim. Cosmochim. Acta 74, 264 (2010)]. The predicted isotope fractionations for hydrated bromine and HBr, Br2 gases are very small, 1000 ln α, do not exceed 0.8‰; thus, the expected variations of bromine isotope composition in aqua-gas systems will require enhanced precision for their detection. In contrast, the sulphur isotope fractionation between H2S gas and S2− attains 6.0‰ at room temperature and drops nearly linearly to 3.1‰ at 350°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.

TLC-MS VERSUS TLC-LC-MS FINGERPRINTS OF HERBAL EXTRACTS. PART II. PHENOLIC ACIDS AND FLAVONOIDS

In the previous paper from this series, we proposed mass spectrometric fingerprinting of a complex and volatile botanical sample upon an example of the essential oil derived from Salvia lavandulifolia. In that paper, we compared two variants of fractionation of such a mixture. A simpler one-dimensional variant consisted of the low-temperature thin-layer chromatographic fractionation coupled with mass spectrometric fingerprinting of each separated fraction (1D LT TLC-MS). A more sophisticated variant was the two-dimensional liquid chromatographic system composed of the low-temperature thin-layer chromatography, high-performance liquid chromatography, and mass spectrometric detection (2D LT TLC-LC-MS). In this study, we present an analogous approach to the non-volatile botanical mixtures upon an example of the pharmacologically important phenolic acids and flavonoids selectively extracted from Salvia lavandulifolia. With these non-volatile fractions, the thin-layer chromatographic separations were carried out at ambient temperature (21 ± 0.5°C). Once again, we compared two variants of fractionation. A simpler one-dimensional variant consisted of the thin-layer chromatographic mode coupled with mass spectrometric fingerprinting of each separated fraction (1D TLC-MS). A more sophisticated variant was the two-dimensional liquid chromatographic system composed of the thin-layer chromatography and high-performance liquid chromatography, with mass spectrometric detection (2D TLC-LC-MS). As expected, the two-dimensional mode proved better performing than the one-dimensional mode (1D TLC-MS). It was concluded that thin-layer chromatography directly or indirectly coupled with mass spectrometric detection can prove very useful in the analysis of the phenolic acid and flavonoid fraction selectively extracted from botanical material.