Journal articles on the topic 'Fractionation'
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1
Li, Jianghanyang, Xuan Zhang, John Orlando, Geoffrey Tyndall, and Greg Michalski. "Quantifying the nitrogen isotope effects during photochemical equilibrium between NO and NO<sub>2</sub>: implications for <i>δ</i><sup>15</sup>N in tropospheric reactive nitrogen." Atmospheric Chemistry and Physics 20, no. 16 (August 21, 2020): 9805–19. http://dx.doi.org/10.5194/acp-20-9805-2020.
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Abstract. Nitrogen isotope fractionations between nitrogen oxides (NO and NO2) play a significant role in determining the nitrogen isotopic compositions (δ15N) of atmospheric reactive nitrogen. Both the equilibrium isotopic exchange between NO and NO2 molecules and the isotope effects occurring during the NOx photochemical cycle are important, but both are not well constrained. The nighttime and daytime isotopic fractionations between NO and NO2 in an atmospheric simulation chamber at atmospherically relevant NOx levels were measured. Then, the impact of NOx level and NO2 photolysis rate on the combined isotopic fractionation (equilibrium isotopic exchange and photochemical cycle) between NO and NO2 was calculated. It was found that the isotope effects occurring during the NOx photochemical cycle can be described using a single fractionation factor, designated the Leighton cycle isotope effect (LCIE). The results showed that at room temperature, the fractionation factor of nitrogen isotopic exchange is 1.0289±0.0019, and the fractionation factor of LCIE (when O3 solely controls the oxidation from NO to NO2) is 0.990±0.005. The measured LCIE factor showed good agreement with previous field measurements, suggesting that it could be applied in an ambient environment, although future work is needed to assess the isotopic fractionation factors of NO+RO2/HO2→NO2. The results were used to model the NO–NO2 isotopic fractionations under several NOx conditions. The model suggested that isotopic exchange was the dominant factor when NOx>20 nmol mol−1, while LCIE was more important at low NOx concentrations (<1 nmol mol−1) and high rates of NO2 photolysis. These findings provided a useful tool to quantify the isotopic fractionations between tropospheric NO and NO2, which can be applied in future field observations and atmospheric chemistry models.
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Christner, Emanuel, Martin Kohler, and Matthias Schneider. "The influence of snow sublimation and meltwater evaporation on <i>δ</i>D of water vapor in the atmospheric boundary layer of central Europe." Atmospheric Chemistry and Physics 17, no. 2 (January 25, 2017): 1207–25. http://dx.doi.org/10.5194/acp-17-1207-2017.
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Abstract. Post-depositional fractionation of stable water isotopes due to fractionating surface evaporation introduces uncertainty to various isotope applications such as the reconstruction of paleotemperatures, paleoaltimetry, and the investigation of groundwater formation. In this study, we investigate isotope fractionation at snow-covered moisture sources by combining 17 months of observations of isotope concentration ratios [HD16O] ∕ [H216O] in low-level water vapor in central Europe with a new Lagrangian isotope model. The isotope model is capable of reproducing variations of the observed isotope ratios with a correlation coefficient R of 0.82. Observations from 38 days were associated with cold snaps and moisture uptake in snow-covered regions. Deviations between modeled and measured isotope ratios during the cold snaps were related to differences in skin temperatures (Tskin). Analysis of Tskin provided by the Global Data Assimilation System (GDAS) of the NCEP implies the existence of two regimes of Tskin with different types of isotope fractionation during evaporation: a cold regime with Tskin < Tsubl,max = −7.7 °C, which is dominated by non-fractionating sublimation of snow, and a warmer regime with Tsubl,max < Tskin < 0 °C, which is dominated by fractionating evaporation of meltwater. Based on a sensitivity study, we assess an uncertainty range of the determined Tsubl,max of −11.9 to −2.9 °C. The existence of the two fractionation regimes has important implications for the interpretation of isotope records from snow-covered regions as well as for a more realistic modeling of isotope fractionation at snow-covered moisture sources. For these reasons, more detailed experimental studies at snow-covered sites are needed to better constrain the Tsubl,max and to further investigate isotope fractionation in the two regimes.
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Sponheimer, Matt, Todd Robinson, Linda Ayliffe, Ben Passey, Beverly Roeder, Lisa Shipley, Elvia Lopez, Thure Cerling, Denise Dearing, and Jim Ehleringer. "An experimental study of carbon-isotope fractionation between diet, hair, and feces of mammalian herbivores." Canadian Journal of Zoology 81, no. 5 (May 1, 2003): 871–76. http://dx.doi.org/10.1139/z03-066.
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The carbon-isotope composition of hair and feces offers a glimpse into the diets of mammalian herbivores. It is particularly useful for determining the relative consumption of browse and graze in tropical environments, as these foods have strongly divergent carbon-isotope compositions. Fecal δ13C values reflect the last few days consumption, whereas hair provides longer term dietary information. Previous studies have shown, however, that some fractionation occurs between dietary δ13C values and those of hair and feces. Accurate dietary reconstruction requires an understanding of these fractionations, but few controlled-feeding studies have been undertaken to investigate these fractionations in any mammalian taxa, fewer still in large mammalian herbivores. Here, we present data from the first study of carbon-isotope fractionation between diet, hair, and feces in multiple herbivore taxa. All taxa were fed pure alfalfa (Medicago sativa) diets for a minimum period of 6 months, at which point recently grown hair was shaved and analyzed for carbon isotopes. The mean observed diethair fractionation was +3.2, with a range of +2.7 to +3.5. We also examined dietfeces fractionation for herbivores on alfalfa and bermudagrass (Cynodon dactylon) feeds. The mean dietfeces fractionation for both diets was 0.8, with less fractionation for alfalfa (0.6) than bermudagrass (1.0). Fecal carbon turnover also varies greatly between taxa. When diets were switched, horse (Equus caballus) feces reflected the new diet within 60 h, but alpaca (Lama pacos) feces did not equilibrate with the new diet for nearly 200 h. Thus, fecal carbon isotopes provide far greater dietary resolution for hindgut-fermenting horses than foregut-fermenting alpacas.
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Detmers, Jan, Volker Brüchert, Kirsten S. Habicht, and Jan Kuever. "Diversity of Sulfur Isotope Fractionations by Sulfate-Reducing Prokaryotes." Applied and Environmental Microbiology 67, no. 2 (February 1, 2001): 888–94. http://dx.doi.org/10.1128/aem.67.2.888-894.2001.
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ABSTRACT Batch culture experiments were performed with 32 different sulfate-reducing prokaryotes to explore the diversity in sulfur isotope fractionation during dissimilatory sulfate reduction by pure cultures. The selected strains reflect the phylogenetic and physiologic diversity of presently known sulfate reducers and cover a broad range of natural marine and freshwater habitats. Experimental conditions were designed to achieve optimum growth conditions with respect to electron donors, salinity, temperature, and pH. Under these optimized conditions, experimental fractionation factors ranged from 2.0 to 42.0‰. Salinity, incubation temperature, pH, and phylogeny had no systematic effect on the sulfur isotope fractionation. There was no correlation between isotope fractionation and sulfate reduction rate. The type of dissimilatory bisulfite reductase also had no effect on fractionation. Sulfate reducers that oxidized the carbon source completely to CO2 showed greater fractionations than sulfate reducers that released acetate as the final product of carbon oxidation. Different metabolic pathways and variable regulation of sulfate transport across the cell membrane all potentially affect isotope fractionation. Previous models that explained fractionation only in terms of sulfate reduction rates appear to be oversimplified. The species-specific physiology of each sulfate reducer thus needs to be taken into account to understand the regulation of sulfur isotope fractionation during dissimilatory sulfate reduction.
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Laitinen, Ossi, Kalle Kemppainen, Tuomas Stoor, and Jouko Niinimäki. "Fractionation of pulp and paper particles selectively by size." BioResources 6, no. 1 (January 15, 2011): 672–85. http://dx.doi.org/10.15376/biores.6.1.672-685.
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A study was made of the classification of pulp, paper, and peat particles by size with a device called a tube flow fractionator. An accurate and simple experimental model was formulated in order to estimate the time required for fractionation, yielding an excellent correlation between the observed and predicted fractionation times. The results showed that the fractionation time of a certain size of pulp, paper, and peat particles in the tube flow device can be accurately estimated from the length, width, and thickness of the particle. The results can be used to facilitate the selection of specific fractions of pulp and paper samples.
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Fujii, T., F. Moynier, A. Agranier, E. Ponzevera, and M. Abe. "Isotope fractionation of palladium in chemical exchange reaction." Proceedings in Radiochemistry 1, no. 1 (September 1, 2011): 339–44. http://dx.doi.org/10.1524/rcpr.2011.0060.
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Abstract Palladium isotopes were fractionated by the solvent extraction technique with a crown ether. After purification by ion-exchange chemistry, the isotopic ratios of 105Pd/106Pd, 108Pd/106Pd, and 110Pd/106Pd were determined by multiple-collector inductively coupled plasma mass spectrometry. Isotope fractionations between the two phases were found to be larger than 0.1‰. The isotope fractionation of the odd atomic mass isotope (105Pd) showed a deviation from that estimated from the even atomic mass isotopes (106Pd, 108Pd, and 110Pd). The mass-independent isotope fractionation found was attributable to the nuclear field shift effect. The quantum chemical calculations for the different Pd species supported the validity of the isotope fractionation factors obtained.
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Ledgard, SF, KC Woo, and FJ Bergersen. "Isotopic Fractionation During Reduction of Nitrate and Nitrite by Extracts of Spinach Leaves." Functional Plant Biology 12, no. 6 (1985): 631. http://dx.doi.org/10.1071/pp9850631.
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The isotopic fractionations of nitrogen during the reduction of NO3- and NO2- in a cytosolic fraction and in a chloroplast preparation from spinach (Spinacia oleracea L.) leaves were determined. The reduction of NO3- to NH3 was studied using a reconstituted system containing cytosolic extract and intact chloroplasts, while a chloroplast system was used for NO2- reduction. In the reconstituted systems the ratio of nitrate reductase activity to nitrite reductase activity had a large effect on the relative amounts of NO2- and NH3 formed. Ammonia predominated when the nitrate reductase to nitrite reductase activity ratio was 1 : 5 and this ratio was used in the isotopic fractionation studies. Significant isotopic fractionation of N was observed in the reconstituted system but not in the chloroplast system. This indicates that the observed isotopic fractionation was associated with the reduction of NO3- to NO2- by nitrate reductase. The isotopic fractionation (i.e. δ15Nproduct - δ15Nsubstrate) for this reaction was - 15‰.
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Fehér, Anikó, Soma Bedő, and Csaba Fehér. "Comparison of Enzymatic and Acidic Fractionation of Corn Fiber for Glucose-rich Hydrolysate and Bioethanol Production by Candida boidinii." Periodica Polytechnica Chemical Engineering 65, no. 3 (May 18, 2021): 320–30. http://dx.doi.org/10.3311/ppch.17431.
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Corn fiber is a by-product of the corn wet milling process and a promising raw material to produce bioethanol in a bio-refinery process. In this study, enzymatic and acidic fractionations of corn fiber were compared with particular attention to produce glucose-rich hydrolyzates. The acidic fractionation contained two, sequential, sulphuric acid-catalyzed, hydrolysis steps based on our previous study. In the enzymatic fractionation process, corn fiber was pre-treated by soaking in aqueous ammonia (18.5 % (w/w) dry matter, 15 % (w/w) ammonia solution, 24 hours) and then hydrolyzed by using Hemicellulase (NS 22002) enzyme cocktail. The cellulose part of the solid residues obtained after the acidic and enzymatic fractionation processes was enzymatically hydrolyzed by using Cellic Ctec2 and Novozymes 188 (12.5 % (w/w) dry matter, 50 °C, 72 hours). Cellulose hydrolysis after the acidic and enzymatic fractionation resulted in a supernatant containing 64 g/L and 25 g/L glucose, respectively. Therefore, ethanol fermentation experiments were performed in Separated Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF) configurations after the acidic fractionation of corn fiber. SHF configuration was found to be more advantageous regarding the achievable ethanol yield. Although the fermentation with Candida boidinii NCAIM Y.01308 was accomplished within longer time (43 hours) compared to Saccharomyces cerevisiae (5 hours), the achieved ethanol yields were similar (79%) during the SHF process. It was concluded that acidic fractionation is more efficient to produce glucose-rich hydrolyzate from corn fiber compared to enzymatic fractionation, and Candida boidinii is suitable for ethanol fermentation on the glucose-rich hydrolyzate.
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Morasch, Barbara, Hans H. Richnow, Bernhard Schink, and Rainer U. Meckenstock. "Stable Hydrogen and Carbon Isotope Fractionation during Microbial Toluene Degradation: Mechanistic and Environmental Aspects." Applied and Environmental Microbiology 67, no. 10 (October 1, 2001): 4842–49. http://dx.doi.org/10.1128/aem.67.10.4842-4849.2001.
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ABSTRACT Primary features of hydrogen and carbon isotope fractionation during toluene degradation were studied to evaluate if analysis of isotope signatures can be used as a tool to monitor biodegradation in contaminated aquifers. D/H hydrogen isotope fractionation during microbial degradation of toluene was measured by gas chromatography. Per-deuterated toluene-d 8 and nonlabeled toluene were supplied in equal amounts as growth substrates, and kinetic isotope fractionation was calculated from the shift of the molar ratios of toluene-d 8 and nondeuterated toluene. The D/H isotope fractionation varied slightly for sulfate-reducing strain TRM1 (slope of curve [b] = −1.219), Desulfobacterium cetonicum(b = −1.196), Thauera aromatica(b = −0.816), and Geobacter metallireducens (b = −1.004) and was greater for the aerobic bacterium Pseudomonas putidamt-2 (b = −2.667). The D/H isotope fractionation was 3 orders of magnitude greater than the13C/12C carbon isotope fractionation reported previously. Hydrogen isotope fractionation with nonlabeled toluene was 1.7 and 6 times less than isotope fractionation with per-deuterated toluene-d 8 and nonlabeled toluene for sulfate-reducing strain TRM1 (b = −0.728) andD. cetonicum (b = −0.198), respectively. Carbon and hydrogen isotope fractionation during toluene degradation by D. cetonicum remained constant over a growth temperature range of 15 to 37°C but varied slightly during degradation by P. putida mt-2, which showed maximum hydrogen isotope fractionation at 20°C (b = −4.086) and minimum fractionation at 35°C (b = −2.138). D/H isotope fractionation was observed only if the deuterium label was located at the methyl group of the toluene molecule which is the site of the initial enzymatic attack on the substrate by the bacterial strains investigated in this study. Use of ring-labeled toluene-d 5 in combination with nondeuterated toluene did not lead to significant D/H isotope fractionation. The activity of the first enzyme in the anaerobic toluene degradation pathway, benzylsuccinate synthase, was measured in cell extracts of D. cetonicum with an initial activity of 3.63 mU (mg of protein)−1. The D/H isotope fractionation (b = −1.580) was 30% greater than that in growth experiments with D. cetonicum. Mass spectroscopic analysis of the product benzylsuccinate showed that H atoms abstracted from the toluene molecules by the enzyme were retained in the same molecules after the product was released. Our findings revealed that the use of deuterium-labeled toluene was appropriate for studying basic features of D/H isotope fractionation. Similar D/H fractionation factors for toluene degradation by anaerobic bacteria, the lack of significant temperature dependence, and the strong fractionation suggest that analysis of D/H fractionation can be used as a sensitive tool to assess degradation activities. Identification of the first enzyme reaction in the pathway as the major fractionating step provides a basis for linking observed isotope fractionation to biochemical reactions.
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Schoeller, D. A., C. A. Leitch, and C. Brown. "Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, no. 6 (December 1, 1986): R1137—R1143. http://dx.doi.org/10.1152/ajpregu.1986.251.6.r1137.
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The accuracy and precision of the doubly labeled water method for measuring energy expenditure are influenced by isotope fractionation during evaporative water loss and CO2 excretion. To characterize in vivo isotope fractionation, we collected and isotopically analyzed physiological fluids and gases. Breath and transcutaneous water vapor were isotopically fractionated. The degree of fractionation indicated that the former was fractionated under equilibrium control at 37 degrees C, and the latter was kinetically fractionated. Sweat and urine were unfractionated. By use of isotopic balance models, the fraction of water lost via fractionating routes was estimated from the isotopic abundances of body water, local drinking water, and dietary solids. Fractionated water loss averaged 23% (SD = 10%) of water turnover, which agreed with our previous estimates based on metabolic rate, but there was a systematic difference between the results based on O2 and hydrogen. Corrections for isotopic fractionation of water lost in breath and (nonsweat) transcutaneous loss should be made when using labeled water to measure water turnover or CO2 production.
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Alderton, David H. M. "Oxygen isotope fractionation between cassiterite and water." Mineralogical Magazine 53, no. 371 (June 1989): 373–76. http://dx.doi.org/10.1180/minmag.1989.053.371.13.
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Analysis of stable isotopes in coexisting minerals has found wide application in the study of hydrothermal mineral deposits, particularly for elucidating the temperature and source of the fluid phase involved in mineralisation. For these purposes the temperature dependence of isotopic fractionation in several mineral-water systems has already been established (e.g. Friedman and O'Neil, 1977; O'Neil, 1986). Unfortunately, the oxygen isotope fractionation between cassiterite (SnO2) and water has not been adequately characterized, and this has hindered a full utilization of oxygen isotope data derived from studies of tin deposits (e.g. Harzer, 1970; Patterson et al., 1981; Kelly and Rye, 1979). Because of this situation, an attempt is made here to derive a relationship between temperature and the fractionation of oxygen isotopes (Δ) between quartz and cassiterite, based on the fractionations observed in naturally-occurring assemblages and independent temperature estimates.
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Larkomaa, Jaakko, Jouko Niinimäki, Markus Honkanen, Muhammad Hanif, and Pentti Saarenrinne. "Effect of Fibre Properties on Flocculation and Fractionation of Cellulosic Fibres in Dry State." Journal of Engineered Fibers and Fabrics 4, no. 4 (December 2009): 155892500900400. http://dx.doi.org/10.1177/155892500900400408.
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This paper investigates a fractionation method of cellulosic fibres in dry state. Although processing of cellulosic fibres in airstream has been utilised for decades in airlaid processes, no attempts to fractionate fibres in dry state have been reported. Our main goal is to determine how fibre properties and fibre consistency affect fibre flocculation and thus the behaviour of fibres in fractionation. Also evaluations of quality and capacity of fractionation operation are made. Pulp flocculation behaviour is measured with digital imaging and image recognition technique before and after the fractionation device. A doubleview, orthogonal imaging approach is applied obtaining statistics of three-dimensional shape, dimensions and coordinates of detected fibre flocs. Fraction and fibre properties are determined with Metso Fractionator and Metso Fiberlab. Results show that fibre behaviour in a given system strongly depends on the pulp properties. Flocculation was found to be strongly dependent on fibre consistency. Evaluation of fractionation operation was done with help of calculations of mass-reject rates and separation efficiencies. Calculations showed that highest separation efficiencies can be achieved with system when mass-reject rate is between 0.30 and 0.40.
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Sheppard, S. M. F., and H. A. Gilg. "Stable isotope geochemistry of clay minerals." Clay Minerals 31, no. 1 (March 1996): 1–24. http://dx.doi.org/10.1180/claymin.1996.031.1.01.
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AbstractThe equilibrium H- and O-isotope fractionations can be approximated by the following equations which are based on experimental, empirical and/or theoretical data:Hydrogen: 1000 ln αkaolinite-water = −2.2 × 106 × T−2 − 7.7Oxygen: 1000 ln αkaolinite-water = 2.76 × 106 × T−2 − 6.751000 ln αsmectite-water = 2.55 × 106 × T−2 − 4.051000 ln αillite-water = 2.39 × 106 × T−2 − 3.76The equilibrium H-isotope fractionation factors vs. 106 × T−2 for kaolinite and probably smectite and illite are monotonic curves between 350-0°C. More complex curves, with a minimum fractionation near 200°C, are probably influenced by surface effects and/or disequilibrium fractionations among the different hydrogen sites. The H-isotope fractionations between smectite-water increase by ~70‰ from Fe-poor montmorillonite to nontronite at low temperatures. The pore-interlayer water in smectite H-isotope fractionation at low temperatures is ~20±10‰. The presence of organic matter can modify both the δD value of the clay analysis and its ‘water’ content. Clays — kaolinite, illite, smectite and probably halloysite — tend to retain their D/H and 18O/16O ratios unless subjected to more extreme diagenetic or metamorphic conditions or special local processes. Kinetic information is still only qualitative: for comparable grain sizes, hydrogen exchanges more rapidly than oxygen in the absence of recrystallization. Low-temperature diffusion coefficients cannot be calculated with sufficient precision from the higher temperature exchange data. The H- and O-isotope studies of clays can provide useful information about their conditions of formation.
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Hunt, Wendy K., Larry D. Sanford, Richard J. Ross, Adrian R. Morrison, and Allan I. Pack. "Elicited pontogeniculooccipital waves and phasic suppression of diaphragm activity in sleep and wakefulness." Journal of Applied Physiology 84, no. 6 (June 1, 1998): 2106–14. http://dx.doi.org/10.1152/jappl.1998.84.6.2106.
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Fractionations are 20- to 100-ms pauses in diaphragm activity that occur spontaneously during rapid-eye-movement (REM) sleep, sometimes in association with pontogeniculooccipital (PGO) waves. Auditory stimuli can elicit fractionations or PGO waves during REM sleep, non-REM (NREM) sleep, and waking; however, their interrelationship has not been investigated. To determine whether the two phenomena are produced by a common phasic-event generator in REM sleep, we examined PGO waves and fractionations that were elicited by auditory stimuli (tones) presented to freely behaving cats across states. Tones elicited PGO waves and two types of fractionations: short-latency fractionation responses (SFRs; 10- to 60-ms latencies) and long-latency fractionation responses (LFRs; 60- to 120-ms latencies). Both a PGO wave and a SFR were elicited in 60–70% of trials across states, but each could be elicited alone. The latencies and durations of elicited SFRs were similar across states, but the latencies of elicited PGO waves in REM sleep (mean 62.5 ms) were significantly longer than in waking or NREM sleep. Elicited SFRs consistently occur with shorter latencies than do PGO waves, in contrast to spontaneous fractionations, which have a variable relationship to PGO waves and usually occur 10–40 ms after the onset of the PGO wave. The LFR then, elicited most frequently during REM sleep, resembles a spontaneous fractionation in its temporal relationship to the PGO wave and may reflect the bias toward motoneuronal inhibition characterizing REM sleep but not NREM sleep or waking. We conclude that, although PGO waves and SFRs share some features, like LFRs they probably are generated by different neuronal populations. In three cats there was no correlation between PGO waves and fractionations, whereas in one cat they were associated in REM sleep (LFRs and SFRs) and waking (SFRs only). Thus the majority of evidence argues against the existence of a common phasic-event generator in REM sleep.
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Pellerin, André, Luke Anderson-Trocmé, Lyle G. Whyte, Grant M. Zane, Judy D. Wall, and Boswell A. Wing. "Sulfur Isotope Fractionation during the Evolutionary Adaptation of a Sulfate-Reducing Bacterium." Applied and Environmental Microbiology 81, no. 8 (February 6, 2015): 2676–89. http://dx.doi.org/10.1128/aem.03476-14.
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ABSTRACTDissimilatory sulfate reduction is a microbial catabolic pathway that preferentially processes less massive sulfur isotopes relative to their heavier counterparts. This sulfur isotope fractionation is recorded in ancient sedimentary rocks and generally is considered to reflect a phenotypic response to environmental variations rather than to evolutionary adaptation. Modern sulfate-reducing microorganisms isolated from similar environments can exhibit a wide range of sulfur isotope fractionations, suggesting that adaptive processes influence the sulfur isotope phenotype. To date, the relationship between evolutionary adaptation and isotopic phenotypes has not been explored. We addressed this by studying the covariation of fitness, sulfur isotope fractionation, and growth characteristics inDesulfovibrio vulgarisHildenborough in a microbial evolution experiment. After 560 generations, the mean fitness of the evolved lineages relative to the starting isogenic population had increased by ∼17%. After 927 generations, the mean fitness relative to the initial ancestral population had increased by ∼20%. Growth rate in exponential phase increased during the course of the experiment, suggesting that this was a primary influence behind the fitness increases. Consistent changes were observed within different selection intervals between fractionation and fitness. Fitness changes were associated with changes in exponential growth rate but changes in fractionation were not. Instead, they appeared to be a response to changes in the parameters that govern growth rate: yield and cell-specific sulfate respiration rate. We hypothesize that cell-specific sulfate respiration rate, in particular, provides a bridge that allows physiological controls on fractionation to cross over to the adaptive realm.
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Liu, Junli, and Bernard Tao. "Fractionation of fatty acid methyl esters via urea inclusion and its application to improve the low-temperature performance of biodiesel." Biofuel Research Journal 9, no. 2 (June 1, 2022): 1617–29. http://dx.doi.org/10.18331/brj2022.9.2.3.
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Biodiesel is viewed as the alternative to petroleum diesel, but its poor low-temperature performance constrains its utilization. Cloud point (CP), the onset temperature of thermal crystallization, appropriately shows the low-temperature performance. The effective way to reduce CP is to remove saturated fatty acid methyl esters (FAMEs). Compared to current methods, this work describes an extraordinary approach to fractionating FAMEs by forming solid urea inclusion compounds (UICs). Urea inclusion fractionation reduces the CPs by removing high melting-point linear saturated FAME components. Urea inclusion fractionation in this study was performed under various processing conditions: mass ratios of urea to FAMEs and solvents to FAMEs, various solvents, FAMEs from various feedstocks, and processing temperatures. Supersaturation of urea in the solution is the driving force, and it significantly affects yield, composition, CP, separation efficiency, and selectivity. Through a single urea inclusion fractionation process, FAMEs, except palm oil FAMEs, resulted in CP reduction ranging from 20 to 42 oC with a yield of 77–80% depending on the compositions. CP of palm oil FAMEs could reach as low as -17 oC with a yield of 46% after twice urea inclusion fractionation. According to the model prediction, the cetane number after urea inclusion fractionation decreased about 0.7–2 but was still higher than the minimum biodiesel requirement. Oxidation stability after urea inclusion decreased according to the proposed model, but this can be mitigated by adding antioxidants. Emission evaluation after urea inclusion fractionation indicated decreased hydrocarbons, carbon monoxide, and particulate matter. However, it resulted in the increasing emission of nitrogen oxides.
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Van Dongen, Joris A., Olivier F. E. Gostelie, Lucienne A. Vonk, Julia J. De Bruijn, Berend Van Der Lei, Martin C. Harmsen, and Hieronymus P. Stevens. "Fractionation of Adipose Tissue Procedure With a Disposable One-Hole Fractionator." Aesthetic Surgery Journal 40, no. 4 (August 12, 2019): NP194—NP201. http://dx.doi.org/10.1093/asj/sjz223.
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Abstract Background Adipose tissue has been widely used in regenerative surgery for its therapeutic potential. This potential is often ascribed to the stromal vascular fraction (SVF), which can be mechanically isolated. Mechanical isolation results in an SVF that retains intact cell-cell communication including extracellular matrix and is therefore named tissue-SVF (tSVF). Objectives The aim of this study was to evaluate a new disposable 1-hole fractionator for fractionation of adipose tissue (FAT), and compare this new device with the existing reusable 3-hole fractionator. Methods The composition of tSVF obtained via the 1-hole fractionator was histologically and histochemically compared to unprocessed adipose tissue. The number of viable nuclear cells in tSVF obtained by the 1-hole and 3-hole fractionators as well as unprocessed adipose tissue were compared after enzymatic isolation and tested for colony-forming capacity. Flow cytometry was used to compare different cell compositions based on surface marker expression between tSVF isolated by the two types of fractionators. Results Fractionation of adipose tissue with the 1-hole fractionator condenses vasculature and extracellular matrix by disrupting adipocytes. The number of viable nuclear cells in tSVF obtained with the two fractionators was comparable and significantly higher than unprocessed lipoaspirate. Furthermore, tSVF isolated by both fractionators showed similar cell compositions and comparable colony-forming capacities. Conclusions FAT with a disposable 1-hole fractionator effectively isolates tSVF with a cell count and cell composition comparable to the fraction obtained with the 3-hole reusable fractionator. The disposable 1-hole fractionator, however, is safer and more user friendly.
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Yogabalan, Keerthaanaa, Mohd Zahri Abdul Aziz, Gokula Kumar Appalanaido, and Jayapramila Jayamani. "Evaluation of the Dosimetric Parameters of the Interstitial HDR Liver Brachytherapy at USM." Asian Journal of Medicine and Biomedicine 6, S1 (November 4, 2022): 21–22. http://dx.doi.org/10.37231/ajmb.2022.6.s1.510.
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There are numerous treatment options available to treat hepatocellular carcinoma (HCC). Up to now, stereotactic body radiotherapy (SBRT) has been considered the best option to cure the HCC, however SBRT does not adequately spare the nearby organ at risk (OAR) [1]. A high dose rate interstitial brachytherapy (HDR IBT) technique for HCC is considered as an alternative to the SBRT due to accurate and precise dose delivery to the target and well spared adjacent OAR [2]. The main objective of this retrospective study was to evaluate the dosimetry tolerance for the tumour and OAR for HDRIBT technique for HCC technique using the iridium-192 (Ir-192) source.
A computed tomography (CT) image-guided for 41 patients with 71 treatment cases in USM were used to analyse the dose distribution in tumour (HCC) and the OAR (diaphragm). The computed dosimetry data from the Oncentra treatment planning system (v.4.3) was used to analyse the relationship between the dosimetric variables, of the prescribed dose (15 Gy – 25 Gy) and fractionation used for the HDRIBT for HCC by statistical analysis.
In this study, 95% of the gross tumour volume (GTV) of HCC adequately achieved the prescribed dose in both single and multiple fractionations. The GTV dose decreased as the GTV volume increased for all the prescribed doses. Apart from that, the prescribed doses, 20 Gy and 25 Gy, exhibited a higher diaphragm dose in single fractionation treatment compared to 15 Gy dose. Meanwhile, the multiple fractionations treatment also exhibited a remarkably high diaphragm dose compared to the single fractionation treatment.
The minimum GTV dose recommended was based on a comparison with the RTOG 0438, liver SBRT protocol. These recommended values were applicable in both single and multiple fractionations. In addition, it is also applicable in a prescribed dose of 15y – 25 Gy. In short, the minimum recommended GTV doses were the V99% 90% of the prescribed dose, V95% 95% of the prescribed dose V90% 100% of the prescribed dose, respectively. Meanwhile, the diaphragm tolerance dose in this study was compared with RTOG 0438 protocol of ribs tolerance dose, within 54 Gy. Therefore, the diaphragm tolerance dose recommended for diaphragm volume of 0.2cm3, 0.5cm3 and 2.0cm3 (15 Gy prescribed dose) < 10 Gy, (20 Gy prescribed dose) < 15 Gy and (25 Gy prescribed dose) < 20 Gy in single fractionation respectively for all prescribed dose, whereas for the multiple fractionations < 54 Gy, regardless of the GTV volume. In conclusion, HDRIBT technique for HCC is the most promising technique by maximizing the dose to the GTV and reducing dose to the diaphragm by both single and multiple fractionations.
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Wang, Wei, Jiang, Liu, Lei, Lin, and Zhao. "Silicon Isotope Geochemistry: Fractionation Linked to Silicon Complexations and Its Geological Applications." Molecules 24, no. 7 (April 10, 2019): 1415. http://dx.doi.org/10.3390/molecules24071415.
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The fundamental advances in silicon isotope geochemistry have been systematically demonstrated in this work. Firstly, the continuous modifications in analytical approaches and the silicon isotope variations in major reservoirs and geological processes have been briefly introduced. Secondly, the silicon isotope fractionation linked to silicon complexation/coordination and thermodynamic conditions have been extensively stressed, including silicate minerals with variable structures and chemical compositions, silica precipitation and diagenesis, chemical weathering of crustal surface silicate rocks, biological uptake, global oceanic Si cycle, etc. Finally, the relevant geological implications for meteorites and planetary core formation, ore deposits formation, hydrothermal fluids activities, and silicon cycling in hydrosphere have been summarized. Compared to the thermodynamic isotope fractionation of silicon associated with high-temperature processes, that in low-temperature geological processes is much more significant (e.g., chemical weathering, biogenic/non-biogenic precipitation, biological uptake, adsorption, etc.). The equilibrium silicon isotope fractionation during the mantle-core differentiation resulted in the observed heavy isotope composition of the bulk silicate Earth (BSE). The equilibrium fractionation of silicon isotopes among silicate minerals are sensitive to the Si–O bond length, Si coordination numbers (CN), the polymerization degrees of silicate unites, and the electronegativity of cations in minerals. The preferential enrichment of different speciation of dissoluble Si (DSi) (e.g., silicic acid H4SiO40 (H4) and H3SiO4− (H3)) in silica precipitation and diagenesis, and chemical weathering, lead to predominately positive Si isotope signatures in continental surface waters, in which the dynamic fractionation of silicon isotope could be well described by the Rayleigh fractionation model. The role of complexation in biological fractionations of silicon isotopes is more complicated, likely involving several enzymatic processes and active transport proteins. The integrated understanding greatly strengthens the potential of δ30Si proxy for reconstructing the paleo terrestrial and oceanic environments, and exploring the meteorites and planetary core formation, as well as constraining ore deposits and hydrothermal fluid activity.
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Jin, Xin, Changlu Hu, Asif Khan, Shulan Zhang, Xueyun Yang, Lijie Jia, and Ruipu Sun. "Comparison of fractionation methods for soil phosphorus with soils subjected to various long-term fertilization regimes on a calcareous soil." PeerJ Inorganic Chemistry 3 (June 29, 2021): e3. http://dx.doi.org/10.7717/peerj-ichem.3.
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Background Diverse phosphorus (P) fractionation procedures presented varying soil P fractions, which directly affected P contents and forms, and their biological availability. Purpose To facilitate the selection of phosphorus (P) fractionation techniques, we compared two procedures based on a long-term experiment on a calcareous soil. Methods The soils containing a gradient P levels were sampled from seven treatments predictor under various long-term fertilizations. The P fractions were then separated independently with both fractionation procedures modified by Tiessen-Moir and Jiang-Gu. Results The results showed that the labile P in Jiang-Gu is significantly lower than that in Tiessen-Moir. The iron and aluminium-bounded P were greater in Jiang-Gu by a maximum of 46 mg kg−1 than Tiessen-Moir. Jiang-Gu fractionation gave similar Ca bounded P to that Tiessen-Moir did at low P level but greater contents at high P level. The two methods extracted much comparable total inorganic P. However, Tiessen-Moir method accounted less total organic P than ignition or Jiang-Gu method (the organic P (Po) estimated by subtract the total inorganic P (Pi) in Jiang-Gu fractionation from the total). P uptake by winter wheat was significantly and positively correlated with all phosphorus fractions in Jiang-Gu; Resin-P, NaHCO3-Pi, D. HCl-P, C. HCl-Pi, NaOH-Po, total-Po in Tiessen-Moir; P fraction categories of Ca-P, Fe & Al-P and total-Pi in both fractionations. Path coefficients indicated that Ca2-P in Jiang-Gu, NaHCO3-Pi and D. HCl-P in Tiessen-Moir had the higher and more significant direct contributions to P uptake among P fractions measured. Conclusions Our results suggested that Jiang-Gu procedure is a better predictor in soil P fractionation in calcareous soils, although it gives no results on organic P fractions.
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Frank, Uwe, Jana Dienstbier, Florentin Tischer, Simon E. Wawra, Lukas Gromotka, Johannes Walter, Frauke Liers, and Wolfgang Peukert. "Multidimensional Fractionation of Particles." Separations 10, no. 4 (April 13, 2023): 252. http://dx.doi.org/10.3390/separations10040252.
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The increasing complexity in particle science and technology requires the ability to deal with multidimensional property distributions. We present the theoretical background for multidimensional fractionations by transferring the concepts known from one dimensional to higher dimensional separations. Particles in fluids are separated by acting forces or velocities, which are commonly induces by external fields, e.g., gravitational, centrifugal or electro-magnetic fields. In addition, short-range force fields induced by particle interactions can be employed for fractionation. In this special case, nanoparticle chromatography is a recent example. The framework for handling and characterizing multidimensional separation processes acting on multidimensional particle size distributions is presented. Illustrative examples for technical realizations are given for shape-selective separation in a hydrocyclone and for density-selective separation in a disc separator.
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Morasch, Barbara, Hans H. Richnow, Andrea Vieth, Bernhard Schink, and Rainer U. Meckenstock. "Stable Isotope Fractionation Caused by Glycyl Radical Enzymes during Bacterial Degradation of Aromatic Compounds." Applied and Environmental Microbiology 70, no. 5 (May 2004): 2935–40. http://dx.doi.org/10.1128/aem.70.5.2935-2940.2004.
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ABSTRACT Stable isotope fractionation was studied during the degradation of m-xylene, o-xylene, m-cresol, and p-cresol with two pure cultures of sulfate-reducing bacteria. Degradation of all four compounds is initiated by a fumarate addition reaction by a glycyl radical enzyme, analogous to the well-studied benzylsuccinate synthase reaction in toluene degradation. The extent of stable carbon isotope fractionation caused by these radical-type reactions was between enrichment factors (ε) of −1.5 and −3.9, which is in the same order of magnitude as data provided before for anaerobic toluene degradation. Based on our results, an analysis of isotope fractionation should be applicable for the evaluation of in situ bioremediation of all contaminants degraded by glycyl radical enzyme mechanisms that are smaller than 14 carbon atoms. In order to compare carbon isotope fractionations upon the degradation of various substrates whose numbers of carbon atoms differ, intrinsic ε (εintrinsic) were calculated. A comparison of εintrinsic at the single carbon atoms of the molecule where the benzylsuccinate synthase reaction took place with compound-specific ε elucidated that both varied on average to the same extent. Despite variations during the degradation of different substrates, the range of ε found for glycyl radical reactions was reasonably narrow to propose that rough estimates of biodegradation in situ might be given by using an average ε if no fractionation factor is available for single compounds.
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Zheng, Yong-Fei. "Oxygen isotope fractionation in wolframite." European Journal of Mineralogy 4, no. 6 (December 15, 1992): 1331–36. http://dx.doi.org/10.1127/ejm/4/6/1331.
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Blunier, T., M. L. Bender, B. Barnett, and J. C. von Fischer. "Planetary fertility during the past 400 ka based on the triple isotope composition of O<sub>2</sub> in trapped gases from the Vostok ice core." Climate of the Past 8, no. 5 (October 10, 2012): 1509–26. http://dx.doi.org/10.5194/cp-8-1509-2012.
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Abstract. The productivity of the biosphere leaves its imprint on the isotopic composition of atmospheric oxygen. Ultimately, atmospheric oxygen, through photosynthesis, originates from seawater. Fractionations during the passage from seawater to atmospheric O2 and during respiration affect δ17O approximately half as much as δ18O. An "anomalous" (also termed mass independent) fractionation process changes δ17O about 1.7 times as much as δ18O during isotope exchange between O2 and CO2 in the stratosphere. The relative rates of biological O2 production and stratospheric processing determine the relationship between δ17O and δ18O of O2 in the atmosphere. Variations of this relationship thus allow us to estimate changes in the rate of O2 production by photosynthesis versus the rate of O2–CO2 isotope exchange in the stratosphere. However, the analysis of the 17O anomaly is complicated because each hydrological and biological process fractionates δ17O and δ18O in slightly different proportions. In this study we present O2 isotope data covering the last 400 ka (thousand years) from the Vostok ice core. We reconstruct oxygen productivities from the triple isotope composition of atmospheric oxygen with a box model. Our steady state model for the oxygen cycle takes into account fractionation during photosynthesis and respiration by the land and ocean biosphere, fractionation during the hydrologic cycle, and fractionation when oxygen passes through the stratosphere. We consider changes of fractionation factors linked to climate variations, taking into account the span of estimates of the main factors affecting our calculations. We find that ocean oxygen productivity was within 20% of the modern value throughout the last 400 ka. Given the presumed reduction in terrestrial oxygen productivity, the total oxygen production during glacials was likely reduced.
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Erez, Jonathan, Anne Bouevitch, and Aaron Kaplan. "Carbon isotope fractionation by photosynthetic aquatic microorganisms: experiments with Synechococcus PCC7942, and a simple carbon flux model." Canadian Journal of Botany 76, no. 6 (June 1, 1998): 1109–18. http://dx.doi.org/10.1139/b98-067.
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Stable carbon isotopes (12C and 13C) are widely used to trace biogeochemical processes in the global carbon cycle. Natural fractionation of carbon isotopes is mainly due to the discrimination of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) against 13C during photosynthesis. In marine and other aquatic microorganisms, this fractionation is lowered when the dissolved CO2 (CO2(aq)) is decreasing, but the underlying mechanisms are poorly understood. Cultured Synechococcus PCC7942 showed maximum isotopic fractionations of -33omicron (in delta 13C units) relative to the total inorganic carbon (Ci) when CO2(aq) is above 30 m M. As the culture grew, pH increased, CO2(aq) was lower than 1 m M, and the Ci concentrating mechanism was induced although the Ci was above 3 mM. The isotopic fractionation was drastically reduced to values of -1 to -3 omicron relative to Ci. A simple carbon isotope flux model suggests that during the first stages of the experiment the total uptake (F1) was roughly three- to four-fold greater than the photosynthetic net accumulation (F2). When the Ci concentrating mechanism was induced, the leakage of CO2 from the cells declined, the cells started to utilize HCO3- and the F1/F2 ratio decreased to values close to 1. Based on this model the isotopic variability of oceanic phytoplankton suggests that the F1/F2 ratio may be above 3 in high latitudes and ~1.1 in equatorial waters, where the Ci concentrating mechanism is probably induced. Attempts to reconstruct past atmospheric CO2 levels and paleoproductivity should take into account the effects of the Ci concentrating mechanism on the isotopic fractionation of aquatic primary producers.Key words: carbon concentrating mechanism, carbon isotope fractionation, CO2, photosynthesis.
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Leger, Cheryl A., Felisa D. Chan, and Marc H. Schneider. "Fractionation and characterisation of technical ammonium lignosulfonate." BioResources 5, no. 4 (August 27, 2010): 2239–47. http://dx.doi.org/10.15376/biores.5.4.2239-2247.
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It is difficult to use lignin in any analytical methodology without reducing its considerable polydispersity by fractionation. An ammonium lignosulphonate sample was fractionated using a method of partial solubility in solutions of isopropanol increasingly diluted with distilled water, effectively fractionating by polarity. Selected fractions were characterised by gravimetric determination of the fractions, and determination of acid insoluble lignin, soluble lignin, and carbohydrate contents. Acid-insoluble lignin content was very low, and soluble lignin provided the majority of the lignin content, as should be expected from sulphonated lignin. Carbohydrate contents were also fairly low, the highest percentage at 14.5 being in Fraction 2, with the bulk lignin and Fraction 3 having 6.5% and 3.2%, respectively. Differences in the composition of each fraction support the efficacy of the fractionation process and permitted selection of fractions for use in subsequent studies.
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Armijo, Carlos, Derek Whitelock, and Ed Hughs. "Assessing a Pneumatic Fractionator as a Lint Cleaning Device." Journal of Cotton Science 19, no. 2 (July 2015): 307–18. http://dx.doi.org/10.56454/tzhp9943.
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A pneumatic fractionator was assessed as a lint cleaning device for ginned lint. Results from a test that used two line pressures and three fractionation times showed that higher line pressure and longer fractionation time produced fiber that was shorter in staple length, contained more neps, and had less dust, trash, and visible foreign matter (including leaf). Short fiber content was not different among fractionator treatments, and all treatments had varying degrees of classer prep calls. The fractionator was effective in removing foreign matter. Overall, the least aggressive treatment had the best fiber properties, and the most aggressive fractionator treatment did the most cleaning. Results from a lint cleaning test that compared the least and most aggressive fractionator treatments with a conventional saw-type lint cleaner showed that the fractionator did not preserve fiber length any better than conventional lint cleaning. The most aggressive fractionator treatment was more effective in removing foreign matter, but had considerably more neps than conventional lint cleaning. The fractionator treatments received prep calls and the conventional lint cleaner treatments did not. The most aggressive fractionator treatment was more harmful to fiber than conventional lint cleaning, and the least aggressive treatment had fiber properties similar to one saw-type lint cleaner. The most aggressive fractionator treatment had the highest cleaning efficiency, largest amount of lint cleaner waste, and lowest bale value. The highest bale value was achieved with either no lint cleaning or with the least aggressive fractionator treatment. Further work is needed to determine the interactions of the fractionator with different cultivars and cottons of varying foreign matter content as well as determine any effects of the fractionator on spinning performance.
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Kaboré, Bénéwendé Aristide, Syeda Dua Taqi, Athumani Mkinga, Anibal E. Morales Zambrana, Robert L. Mach, Marc JB Vreysen, and Chantel J. de Beer. "Radiation dose fractionation and its potential hormetic effects on male Glossina palpalis gambiensis (Diptera: Glossinidae): a comparative study of reproductive and flight quality parameters." Parasite 31 (2024): 4. http://dx.doi.org/10.1051/parasite/2024001.
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One of the most critical factors for implementing the sterile insect technique for the management of tsetse is the production of large quantities of highly competitive sterile males in the field. Several factors may influence the biological quality of sterile males, but optimizing the irradiation protocols to limit unwanted somatic cell damage could improve male performance. This study evaluated the effect of fractionation of gamma radiation doses on the fertility and flight quality of male Glossina palpalis gambiensis. Induced sterility was assessed by mating irradiated males with virgin fertile females. Flight quality was assessed using a standard protocol. The male flies were irradiated as pupae on day 23–27 post larviposition with 110 Gy, either in a single dose or in fractionations of 10 + 100 Gy and 50 + 60 Gy separated by 1-, 2- and 3-day intervals or 55 + 55 Gy separated by 4-, 8-, and 24-hour intervals. All treatments induced more than 90% sterility in females mated with irradiated males, as compared with untreated males. No significant differences were found in emergence rate or flight propensity between fractionated and single radiation doses, nor between the types of fractionations. Overall, the 50(D0) + 60(D1) Gy dose showed slightly higher induced sterility, flight propensity, and survival of males under feeding regime. Dose fractionation resulted in only small improvements with respect to flight propensity and survival, and this should be traded off with the required increase in labor that dose fractionation entails, especially in larger control programs.
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van der Meer, Marcel T. J., Stefan Schouten, Jaap S. Sinninghe Damsté, Jan W. de Leeuw, and David M. Ward. "Compound-Specific Isotopic Fractionation Patterns Suggest Different Carbon Metabolisms among Chloroflexus-Like Bacteria in Hot-Spring Microbial Mats." Applied and Environmental Microbiology 69, no. 10 (October 2003): 6000–6006. http://dx.doi.org/10.1128/aem.69.10.6000-6006.2003.
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ABSTRACT Stable carbon isotope fractionations between dissolved inorganic carbon and lipid biomarkers suggest photoautotrophy by Chloroflexus-like organisms in sulfidic and nonsulfidic Yellowstone hot springs. Where co-occurring, cyanobacteria appear to cross-feed Chloroflexus-like organisms supporting photoheterotrophy as well, although the relatively small 13C fractionation associated with cyanobacterial sugar biosynthesis may sometimes obscure this process.
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Timmerman, Robert. "Beyond Fractionation." Oncology Times 43, no. 24 (December 20, 2021): 1,17–17. http://dx.doi.org/10.1097/01.cot.0000805556.39152.17.
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MORITA, KOZO. "MULTIPLE FRACTIONATION." Japanese Journal of Radiological Technology 47, no. 12 (1991): 2017–24. http://dx.doi.org/10.6009/jjrt.kj00003322753.
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Correa de Sa, Daniel D., Nathaniel Thompson, Justin Stinnett-Donnelly, Pierre Znojkiewicz, Nicole Habel, Joachim G. Müller, Jason H. T. Bates, Jeffrey S. Buzas, and Peter S. Spector. "Electrogram Fractionation." Circulation: Arrhythmia and Electrophysiology 4, no. 6 (December 2011): 909–16. http://dx.doi.org/10.1161/circep.111.965145.
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Wang, Baoyong, Chunfang Zheng, and David Sankoff. "Fractionation statistics." BMC Bioinformatics 12, Suppl 9 (2011): S5. http://dx.doi.org/10.1186/1471-2105-12-s9-s5.
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Burnouf, T. "Plasma fractionation." ISBT Science Series 7, no. 1 (June 13, 2012): 62–67. http://dx.doi.org/10.1111/j.1751-2824.2012.01557.x.
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Desai, Ramesh. "Hypo-fractionation." International Journal of Radiation Oncology*Biology*Physics 16, no. 6 (June 1989): 1655. http://dx.doi.org/10.1016/0360-3016(89)90982-6.
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Dijkstra, Albert J. "Dry fractionation." Lipid Technology 24, no. 9 (September 2012): 208–10. http://dx.doi.org/10.1002/lite.201200223.
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Gursoy-Haksevenler, B. Hande, and Idil Arslan-Alaton. "Effects of treatment on the characterization of organic matter in wastewater: a review on size distribution and structural fractionation." Water Science and Technology 82, no. 5 (August 25, 2020): 799–828. http://dx.doi.org/10.2166/wst.2020.403.
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Abstract Since it is difficult to analyze the components of organic matter in complex effluent matrices individually, the use of more collective, but at the same time, specific wastewater characterization methods would be more appropriate to evaluate changes in effluent characteristics during wastewater treatment. For this purpose, size distribution and structural (resin) fractionation tools have recently been proposed to categorize wastewater. There are several case studies available in the scientific literature being devoted to the application of these fractionation methods. This paper aimed to review the most relevant studies dealing with the evaluation of changes in wastewater characteristics using size distribution and structural (resin) fractionation tools. According to these studies, sequential filtration-ultrafiltration procedures, as well as XAD resins, are frequently employed for size and structural fractionations, respectively. This review focuses on the most relevant publications including biological treatment processes, as well as chemical treatment methods such as coagulation-flocculation, electrocoagulation, the Fenton's reagent and ozonation. This study aims at providing an insight into the possible treatment mechanisms and details the understanding what structural features of wastewater components enabled or prevented efficient treatment (removal) or targeted pollutants.
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Xu, Jiayun, Chenyu Li, Lin Dai, Chunlin Xu, Yongda Zhong, Faxin Yu, and Chuanling Si. "Biomass Fractionation and Lignin Fractionation towards Lignin Valorization." ChemSusChem 13, no. 17 (July 30, 2020): 4284–95. http://dx.doi.org/10.1002/cssc.202001491.
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van Nieuwenhuijzen, A. F., J. H. J. M. van der Graaf, M. J. Kampschreur, and A. R. Mels. "Particle related fractionation and characterisation of municipal wastewater." Water Science and Technology 50, no. 12 (December 1, 2004): 125–32. http://dx.doi.org/10.2166/wst.2004.0704.
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Several studies show that a more detailed characterisation of the particulate matter in municipal wastewater gives a better understanding and prediction of removal efficiencies of physical-chemical treatment techniques and the application of optimal chemical dosages. Such a characterisation should include the distribution of contaminants over various particle sizes. This article describes a method and results of experimental and full-scale investigations, conducted to determine how contaminants in wastewater are distributed over different particle sizes. For this purpose, particle size fractionations of wastewater influents originating from more than thirteen WWTP were carried out. One of these fractionations (WWTP Venray) is shown and interpreted in this article. First, the wastewaters were fractionated into 5 to 6 particle fractions (45, 5.0, 1.0/1.2, 0.45 and 0.1 μm) after which the fractions were analyzed for various water quality parameters like organic components, nutrients, salts, solids and turbidity. Based on the results the effects of removal of the different size fractions on design of the biological treatment and energy balance of a wastewater treatment plant can be assessed. The method also indicates whether a certain wastewater is efficiently treatable with physical-chemical pre-treatment methods. It is concluded wastewater fractionation on particle size is very useful, but that wastewater characteristics and particle size distributions should not be generalised, but have to be interpreted as indications for a certain average wastewater composition. To give more insight into the distribution of contaminants over particle size and the particle removal potential, a specific wastewater fractionation has to be carried out per WWTP.
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Keppler, Frank, Enno Bahlmann, Markus Greule, Heinz Friedrich Schöler, Julian Wittmer, and Cornelius Zetzsch. "Mass spectrometric measurement of hydrogen isotope fractionation for the reactions of chloromethane with OH and Cl." Atmospheric Chemistry and Physics 18, no. 9 (May 9, 2018): 6625–35. http://dx.doi.org/10.5194/acp-18-6625-2018.
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Abstract. Chloromethane (CH3Cl) is an important provider of chlorine to the stratosphere but detailed knowledge of its budget is missing. Stable isotope analysis is a potentially powerful tool to constrain CH3Cl flux estimates. The largest degree of isotope fractionation is expected to occur for deuterium in CH3Cl in the hydrogen abstraction reactions with its main sink reactant tropospheric OH and its minor sink reactant Cl atoms. We determined the isotope fractionation by stable hydrogen isotope analysis of the fraction of CH3Cl remaining after reaction with hydroxyl and chlorine radicals in a 3.5 m3 Teflon smog chamber at 293 ± 1 K. We measured the stable hydrogen isotope values of the unreacted CH3Cl using compound-specific thermal conversion isotope ratio mass spectrometry. The isotope fractionations of CH3Cl for the reactions with hydroxyl and chlorine radicals were found to be -264±45 and -280±11 ‰, respectively. For comparison, we performed similar experiments using methane (CH4) as the target compound with OH and obtained a fractionation constant of -205±6 ‰ which is in good agreement with values previously reported. The observed large kinetic isotope effects are helpful when employing isotopic analyses of CH3Cl in the atmosphere to improve our knowledge of its atmospheric budget.
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O'Neill, Hugh St C., and Herbert Palme. "Collisional erosion and the non-chondritic composition of the terrestrial planets." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1883 (September 30, 2008): 4205–38. http://dx.doi.org/10.1098/rsta.2008.0111.
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The compositional variations among the chondrites inform us about cosmochemical fractionation processes during condensation and aggregation of solid matter from the solar nebula. These fractionations include: (i) variable Mg–Si–RLE ratios (RLE: refractory lithophile element), (ii) depletions in elements more volatile than Mg, (iii) a cosmochemical metal–silicate fractionation, and (iv) variations in oxidation state. Moon- to Mars-sized planetary bodies, formed by rapid accretion of chondrite-like planetesimals in local feeding zones within 10 6 years, may exhibit some of these chemical variations. However, the next stage of planetary accretion is the growth of the terrestrial planets from approximately 10 2 embryos sourced across wide heliocentric distances, involving energetic collisions, in which material may be lost from a growing planet as well as gained. While this may result in averaging out of the ‘chondritic’ fractionations, it introduces two non-chondritic chemical fractionation processes: post-nebular volatilization and preferential collisional erosion. In the latter, geochemically enriched crust formed previously is preferentially lost. That post-nebular volatilization was widespread is demonstrated by the non-chondritic Mn/Na ratio in all the small, differentiated, rocky bodies for which we have basaltic samples, including the Moon and Mars. The bulk silicate Earth (BSE) has chondritic Mn/Na, but shows several other compositional features in its pattern of depletion of volatile elements suggestive of non-chondritic fractionation. The whole-Earth Fe/Mg ratio is 2.1±0.1, significantly greater than the solar ratio of 1.9±0.1, implying net collisional erosion of approximately 10 per cent silicate relative to metal during the Earth's accretion. If this collisional erosion preferentially removed differentiated crust, the assumption of chondritic ratios among all RLEs in the BSE would not be valid, with the BSE depleted in elements according to their geochemical incompatibility. In the extreme case, the Earth would only have half the chondritic abundances of the highly incompatible, heat-producing elements Th, U and K. Such an Earth model resolves several geochemical paradoxes: the depleted mantle occupies the whole mantle, is completely outgassed in 40 Ar and produces the observed 4 He flux through the ocean basins. But the lower radiogenic heat production exacerbates the discrepancy with heat loss.
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Chaleepa, K., and J. Ulrich. "Emulsion Fractionation of Coconut Oil: A New Fractionation Technology." Chemical Engineering & Technology 34, no. 4 (March 2, 2011): 557–62. http://dx.doi.org/10.1002/ceat.201000485.
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Gafton, Georgiy, R. Novikov, S. Novikov, M. Gotovchikova, N. Ilin, M. Girshovich, S. Kanaev, Y. Melnik, and Y. Merezhko. "HIGH DOSE RATE BRACHYTHERAPY AS MONOTHERAPY FOR PROSTATE CANCER: FIVE YEAR RESULTS." Problems in oncology 66, no. 4 (April 1, 2020): 404–12. http://dx.doi.org/10.37469/0507-3758-2020-66-4-404-412.
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Purpose: the aim of the study is to assess the effectiveness and safety of prostate cancer treatment (PCa) with high dose rate brachytherapy (BT-HDR) in monotherapy on 5 years of follow-up. Materials and methods: BT-HDR is performed in 198 patients of PCa. The fractionation schedule was presented by two options: two fractionations of 13 Gy in the first group (67 people) and three fractionations of 11.5 Gy in the second (131 patients). The treatment was carried out with 192Ir (Microselectron). Results: the median for patient care was: I group - 59.2 (41.4-90.3), II - 56.1 (39.4-86.4) months. During the follow-up, no patients died from the progression of the PCa. The three-year survival rate without biochemical progression was 98.5%, while the second group had 92.8%; 88.8% and 88.1%, respectively. There were no significant differences in survival rates between the BT-HDR fractionation regimes compared. In most cases, late genito-urinary radiation toxicity was represented by changes that could be characterized as 1st degree. A total of 161 patients with a three-year follow-up period had three cases (1.8%) radiation-induced stenosis urethra (complications of 3 degrees): two of them in the first group, one in the second group. Only one patient (I group) (1.5%) recorded late recto-intestinal toxicity of the 2nd degree. There were no third or higher violations in the observed groups. Conclusions: the studied mono-modes of fractionation of BT- HDR PCa (two factions of 13 Gy and three factions of 11.5 Gy) demonstrated quite acceptable indicators of effectiveness and safety with a five-year period of observation. It has been established that there are no significant differences in the frequency of biochemical relapses, as well as the severity of early and late radiation toxicity in the groups compared.
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Fallai, Carlo, and Patrizia Olmi. "Altered Fractionation Schedules in Radiotherapy of Head and Neck Cancer. A Review." Tumori Journal 78, no. 5 (October 1992): 311–25. http://dx.doi.org/10.1177/030089169207800506.
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The authors review the main contributions of international literature to show the current status in clinical trials on unconventional fractionations of the dose in radiotherapy of head and neck cancers. Several clinical (but only a few randomized) trials have been conducted over the last 15 years using hyperfractionated (HF), accelerated (AF) or mixed (HF-AF) schedules. HF schedules have obtained promising results in terms of local control in comparison with conventional fractionation (CF) of the dose. Improvement in survival was also obtained by the random trials of Pinto and Sanchiz, whereas in EORTC trial no. 22791, the improvement in survival rate was only marginal. A significant increase in local control and, less frequently, in survival has been claimed in several studies using HF-AF. Such data still need to be confirmed by a random study, since EORTC trial 22811 showed superimposable results in comparison with CF. Selection of the most suitable cases for altered fractionation schemes is also being studied in ongoing trials of the EORTC (22851) and RTOG (90-03). As regards acute reactions during and after altered fractionation, they are more severe than after CF. Only pure HF with a dose intensity approximately comparable to CF seems to produce similar acute reactions. Several factors have been found to influence the severity of acute mucosal reactions: interfraction interval, overall treatment time, total dose, and field size. As regards late damage, genuine HF schemes seem to cause roughly equivalent late damage in comparison to CF, whereas high-dose intensity schedules have a higher rate of complications. Interfraction interval, overall treatment time, total dose, fraction size and field size can influence the risk of late sequelae. Before altered fractionations can be considered standard therapy, more data are needed, which should be provided by multicentric randomized trials, some of which are already in progress.
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Fujii, T., F. Moynier, A. Agranier, E. Ponzevera, and M. Abe. "Nuclear field shift effect of lead in ligand exchange reaction using a crown ether." Proceedings in Radiochemistry 1, no. 1 (September 1, 2011): 387–92. http://dx.doi.org/10.1524/rcpr.2011.0069.
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AbstractLead isotopes were fractionated by the liquid-liquid extraction technique between an aqueous phase and a crown ether. After purification by ion-exchange chemistry, the 207Pb/206Pb and 208Pb/206Pb isotopic ratios were measured by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Isotope fractionations > 0.05‰ have been found. The conventional equilibrium mass-dependent isotope effect estimated by an ab initio calculation was smaller than the Pb isotope fractionation experimentally obtained. Conventional mass-dependent isotope fractionation is not a valuable explanation for our results. The nuclear field shift effect, which results from the isotopic change in the nuclear size and shape, was also estimated by an ab initio method combined with a finite nucleus model. The nuclear field shift effect calculated was in agreement with our experimental results. Therefore, this study reports the first nuclear field shift effect of Pb in an equilibrium ligand exchange reaction.
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Giddings, J. Calvin, P. Stephen Williams, and Ronald Beckett. "Fractionating power in programmed field-flow fractionation: exponential sedimentation field decay." Analytical Chemistry 59, no. 1 (January 1987): 28–37. http://dx.doi.org/10.1021/ac00128a007.
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Jechalke, Sven, Mònica Rosell, Paula M. Martínez-Lavanchy, Paola Pérez-Leiva, Thore Rohwerder, Carsten Vogt, and Hans H. Richnow. "Linking Low-Level Stable Isotope Fractionation to Expression of the Cytochrome P450 Monooxygenase-EncodingethBGene for Elucidation of Methyltert-Butyl Ether Biodegradation in Aerated Treatment Pond Systems." Applied and Environmental Microbiology 77, no. 3 (December 10, 2010): 1086–96. http://dx.doi.org/10.1128/aem.01698-10.
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ABSTRACTMultidimensional compound-specific stable isotope analysis (CSIA) was applied in combination with RNA-based molecular tools to characterize methyl tertiary (tert-) butyl ether (MTBE) degradation mechanisms occurring in biofilms in an aerated treatment pond used for remediation of MTBE-contaminated groundwater. The main pathway for MTBE oxidation was elucidated by linking the low-level stable isotope fractionation (mean carbon isotopic enrichment factor [εC] of −0.37‰ ± 0.05‰ and no significant hydrogen isotopic enrichment factor [εH]) observed in microcosm experiments to expression of theethBgene encoding a cytochrome P450 monooxygenase able to catalyze the oxidation of MTBE in biofilm samples both from the microcosms and directly from the ponds. 16S rRNA-specific primers revealed the presence of a sequence 100% identical to that ofMethylibium petroleiphilumPM1, a well-characterized MTBE degrader. However, neither expression of themdpAgenes encoding the alkane hydroxylase-like enzyme responsible for MTBE oxidation in this strain nor the related MTBE isotope fractionation pattern produced by PM1 could be detected, suggesting that this enzyme was not active in this system. Additionally, observed low inverse fractionation of carbon (εCof +0.11‰ ± 0.03‰) and low fractionation of hydrogen (εHof −5‰ ± 1‰) in laboratory experiments simulating MTBE stripping from an open surface water body suggest that the application of CSIA in field investigations to detect biodegradation may lead to false-negative results when volatilization effects coincide with the activity of low-fractionating enzymes. As shown in this study, complementary examination of expression of specific catabolic genes can be used as additional direct evidence for microbial degradation activity and may overcome this problem.
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Schnitzer, Morris. "The in situ analysis of organic matter in soils." Canadian Journal of Soil Science 81, no. 3 (August 1, 2001): 249–54. http://dx.doi.org/10.4141/s00-064.
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Traditionally, studies on soil organic matter (SOM) begin with the extraction of SOM from soils, its fractionation into humic acid, fulvic acid, and humin, followed by de-ashing of each fraction. These are tedious, laborious and inefficient procedures that do not provide any chemical information on these materials. Instead, recently developed methods such as solid-state 13C NMR and pyrolysis – field ionization mass spectrometry (Py-FIMS) can now be used for the in situ analysis of SOM in soils. These methods identify the major chemical components of SOM without extractions and fractionations, and yield valuable information on the main chemical structures in these materials. A better knowledge of the structural chemistry of SOM will help SOM chemists and other soil scientists to better understand the complex chemical and biochemical reactions that occur in soils, and will enable them to develop practices that will improve soil management and soil productivity. Key words: Extraction, fractionation, solid state 13C NMR, pyrolysis-field ionization mass spectrometry, chemical composition
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Marentes, E., R. A. Vanderpool, and B. J. Shelp. "Boron-isotope fractionation in plants." Canadian Journal of Plant Science 77, no. 4 (October 1, 1997): 627–29. http://dx.doi.org/10.4141/p97-010.
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Naturally-occurring variations in the abundance of stable isotopes of carbon, nitrogen, oxygen, and other elements in plants have been reported and are now used to understand various physiological processes in plants. Boron (B) isotopic variation in several plant species has been documented, but no determination as to whether plants fractionate the stable isotopes of boron, 11B and 10B, has been made. Here, we report that plants with differing B requirements (wheat, corn and broccoli) fractionated boron. The whole plant was enriched in 11B relative to the nutrient solution, and the leaves were enriched in 10B and the stem in 11B relative to the xylem sap. Although at present, a mechanistic role for boron in plants is uncertain, potential fractionating mechanisms are discussed. Key words: Brassica oleracea var. italica Plenck (broccoli), Triticum aestivum L. (wheat), Zea mays L. (corn), boron, isotope fractionation
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Andersen, Morten B., Claudine H. Stirling, and Stefan Weyer. "Uranium Isotope Fractionation." Reviews in Mineralogy and Geochemistry 82, no. 1 (2017): 799–850. http://dx.doi.org/10.2138/rmg.2017.82.19.
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