Partitioning Fraction Research Articles

Austenite Evolution and Solute Partitioning during Thermal Cycling in the Intercritical Range of a Medium-Mn Steel

The evolution of austenite fraction and the associated solute partitioning during the intercritical annealing of medium-Mn steels are of great importance for austenite stabilization and the mechanical performance of this class of steels. In the present work, a 4.5Mn steel is subjected to a cyclic treatment and the evolution of the austenite fraction is measured with dilatometry. The evolution of austenite fraction and solute partitioning are simulated for a case where the starting time of the cyclic treatment is well before the equilibrium fractions have been established in the respective isothermal intercritical treatment. The evolution of austenite during thermal cycling in the intercritical range comprises of forward, inverse, and stagnant stages. The fraction of austenite formed decreases in each successive cycle while the kinetics of the evolution of austenite is controlled by the Mn diffusion in ferrite. Partitioning of Mn and C takes place from ferrite to austenite during the cyclic transformation. Due to the low diffusivity in austenite, wells form in the composition profiles in austenite of both Mn and C. These wells are the locus of the interfacial compositions of austenite, corresponding to the variation of the local equilibrium conditions during the thermal cycle.

Multichannel Analysis of Cell Range Expansion and Resource Partitioning in Two-Tier Heterogeneous Cellular Networks

Cellular heterogeneous networks (HetNets) can improve capacity by offloading users from congested macro cells to lightly loaded small cells through biased association known as cell range expansion (CRE). However, the offloaded (range-expanded) users must be protected from macro interference through time/frequency resource partitioning. In this paper, we develop an analytical framework to evaluate the performance gain due to CRE further supported by resource partitioning in two-tier (macro-pico) networks with multichannel downlinks, e.g., those based on orthogonal frequency division multiple access (OFDMA). By exploiting the flexibility in subchannel allocation offered by OFDMA, frequency-domain resource partitioning is proposed in which the macro tier is muted on a fraction of total subchannels, which are allocated exclusively to range-expanded pico users. The load perceived by a base-station is a key factor in determining its interference contribution over the network and is directly affected by user offloading and resource partitioning. Thus, the analysis of such systems must incorporate cell load. While previous studies mostly rely on full-load assumption, in this paper, we properly characterize cell load as the function of user density, association bias and resource partitioning fraction. We then, evaluate the performance in terms of average user data rate over the entire network, and also investigate the optimal choice of association bias and resource partitioning fraction.

The Synchrotron Radiation for Steel Research

The synchrotron X-ray radiation is a great tool in materials characterization with several advantageous features. The high intensity allows clear interaction signals and high energy of X-ray yields higher sampling volume. The samples do not need extra preparation and the microstructure is therefore not affected. With the tunability of the X-ray energy, a large range of elements and features in the samples can be investigated by different techniques, which is a significant difference between a stand-alone X-ray tube and synchrotron X-ray. Moreover, any experimental equipment can be installed through which the synchrotron beam travels. This facilitates the so-called in situ characterization such as during heat treatment, hot deformation, chemical reaction or welding. Although steel which possesses rather high density requires very high energy X-ray for large interaction volume, lower energy is still effective for the investigation of local structure of nanoconstituents. This work picks up a couple examples employing synchrotron X-ray for the characterization of high strength steels. The first case is the quantification of precipitates in high strength low alloyed (HSLA) steel by X-ray absorption spectroscopy. The other case is the in situ X-ray diffraction for phase fraction and carbon partitioning in multiphase steels such as transformation induced plasticity (TRIP) steel.

Research note. Visualisation of summer heat intensity for different settlement types and varying surface fraction partitioning

Urban planners and stakeholders require knowledge about the effectiveness of city-scale climate adaptation measures in order to develop climate resilient cities and to push forward the political process for the implementation of climate adaptation strategies in cities. This study examines the impact of modifications in urban surface fractions of buildings, impervious and pervious surfaces on summer air temperatures using urban climate modelling of idealised cities. Sensitivity tests are performed for nine typical settlement types in Germany. The results for minimum and maximum temperatures are analysed and plotted in a ternary diagram. The novel approach of using ternary diagrams for the aggregation and visualisation of modelling results clearly identifies thermally unfavourable ranges of urban surface partitioning that should be avoided for urban settlements. Furthermore, the diagrams are used to derive quantitative recommendations for the most effective reduction of summer heat intensity.

Kinetics of Solute Partitioning During Intercritical Annealing of a Medium-Mn Steel

The evolution of austenite fraction and solute partitioning (Mn, Al, and C) during intercritical annealing was calculated for a medium-Mn steel containing 11 pct Mn. Austenite growth takes place in three stages. The first stage is growth under non-partitioning local equilibrium (NPLE) controlled by carbon diffusion in ferrite. The second stage is growth under partitioning local equilibrium (PLE) controlled by diffusion of Mn in ferrite. The third stage is shrinkage of austenite under PLE controlled by diffusion of Mn in austenite. During PLE growth, the austenite is progressively enriched in Mn. Compositional spikes evolve early during NPLE growth and broaden with annealing temperature and time.

Particle Size Fraction and Arsenic Partitioning in Tailings and Sediments in Lianhuashan Tungsten Mine, Southern China

A series of tailings and sediments samples were collected from Linahuashan tungsten mining area. Particle composition, arsenic concentrations and arsenic speciation distribution in the tailings and sediments were investigated. The proportion of large particle (> 170 μm) in the tailings varied from 37% to 50%. Arsenic (As) concentrations in the tailings ranged from1889 mg·kg-1to 3135 mg·kg-1. The sediments upstream were similar to those in the tailings in particle composition, As concentrations and speciation distribution. The sediments in the middle or lower reaches of the stream contained finer texture and lower As concentrations than the tailings. Compared to the tailings, Acid waste water with a lot of tailings particle enter the stream. Most of larger particle in acid waste water settled upstream, and smaller particle and soluble As precipitated in the middle or lower reaches of the stream. Smaller particle fraction contained higher percentages of Fe-As, Ca-As and Al-As, while larger particle fraction contained higher percentages of FeOc-As and Res-As.

Uptake of sevoflurane limited by the presence of cholesterol in the lipid bilayer membrane: a multinuclear nuclear magnetic resonance study.

The effect of cholesterol on the uptake of a fluorinated general anesthetic, sevoflurane (SF, fluoromethyl 2,2,2-trifluoro-1-[trifluoromethyl]ethyl ether) was studied by multinuclear, high-resolution nuclear magnetic resonance (NMR) spectroscopy in combination with a pulsed-field gradient technique. Using large unilamellar vesicles of egg phosphatidylcholine/egg phosphatidylglycerol/cholesterol as model fluid cell membranes, the (19)F and (1)H NMR chemical shifts, longitudinal relaxation times (T1), and diffusion coefficients (D(eff)) were systematically analyzed to quantify the modulation of SF uptake to the lipid membrane by cholesterol. All NMR parameters (chemical shift, T1, and D(eff)) showed that SF uptake is limited by the presence of cholesterol in the membrane. It was found that SF uptake at 40 mol% cholesterol is limited to 50%-60% of the partitioning fraction in the absence of cholesterol in the membrane. This finding is attributed to the loss of motional freedom in the rigid membrane environment, as demonstrated by the gradual slowdown of lipid mobility D(eff) with increase in cholesterol concentration from 0 mol% to 40 mol%.

Elemental Partitioning Characteristics of Equilibrium Phases in Inconel 718 Alloy at 600–1100 °C

The optimization of heat treatment and chemical composition for Inconel 718 alloy has been investigated uninterruptedly because of its excellent mechanical properties and metallurgical workability. The species, chemical compositions and content of equilibrium phases of Inconel 718 alloy in the temperature range of 600−2014;1100 °C were calculated by using thermodynamic software “Thermo-Calc” and the latest relevant datebase of Ni-base superalloys. A concept of elemental partitioning fraction was used to study the partitioning characteristics of alloying elements in each equilibrium phase at different temperatures, such as Ni, Cr, Fe, Nb, Mo, Al, Ti and C, and some calculation results were confirmed under a scanning transmission electron microscope (STEM). The results showed that the elemental partitioning characteristics with the change of temperature revealed the selective partitioning characteristic of alloying elements in equilibrium phases at different temperatures, such as Nb was mainly distributed in δ and γ′ phase, C in carbides, Al and Ti in γ′ phase and Cr, Mo in Laves phase. At the same time, the effect of the change of component and quantity for each precipitated phase on matrix phase can be helpfully understood, which provided a theoretic foundation to optimize the chemical composition and heat treatment in different environments for Inconel 718 alloy.

Simulating the Nutritive Value of Timothy Summer Regrowth

The process‐based grass model, CATIMO, simulates the spring growth and nutritive value of timothy (Phleum pratense L.), a forage species widely grown in Scandinavia and Canada, but the nutritive value of the summer regrowth has never been simulated. Our objective was to improve CATIMO for simulating the N concentration, neutral detergent fiber (NDF), in vitro digestibility of NDF (dNDF), and in vitro true digestibility of dry matter (IVTD) of summer regrowth. Daily changes in summer regrowth nutritive value were simulated by modifying key crop parameters that differed from spring growth. More specifically, the partitioning fraction to leaf blades was increased to increase the leaf‐to‐weight ratio, and daily changes in NDF and dNDF of leaf blades and stems were reduced. The modified CATIMO model was evaluated with data from four independent experiments in eastern and western Canada and Finland. The model performed better for eastern Canada than for the other locations, but the nutritive value attributes of the summer regrowth across locations (range of normalized RMSE = 8–25%, slope < 0.17, R2 < 0.10) were not simulated as well as those of the spring growth (range of normalized RMSE = 4–16%, 0.85 < slope < 1.07, R2 > 0.61). These modeling results highlight knowledge gaps in timothy summer regrowth and prospective research directions: improved knowledge of factors controlling the nutritive value of the timothy summer regrowth and experimental measurements of leaf‐to‐weight ratio and of the nutritive value of leaves and stems.

The influence of Ta on the solidification microstructure and segregation behavior of γ(Ni)/γ′(Ni3Al)–δ(Ni3Nb) eutectic Ni-base superalloys

Polycrystalline γ/γ′–δ eutectic Ni-base superalloys based on the Ni–Al–Nb alloy system were recently demonstrated to possess excellent high temperature strength and creep resistance. Investigations aimed to establish the fundamental relationships between alloy chemistry, solidification behavior and cast microstructure in these novel Ni–Al–Nb γ/γ′–δ alloy systems are currently underway. This particular study is focused on understanding the influence of Ta additions on the solidification sequence, phase volume fraction, distribution coefficient and solid state partitioning parameter of this eutectic alloy system by systematically investigating a series of experimental alloys with nominally constant overall levels of Ta+Nb content but varying Ta/Nb ratios. Although many of the tendencies observed in these multi-component γ/γ′–δ eutectic alloys are in agreement with trends observed in lower order model alloy systems, Ta additions were found to significantly modify solidification characteristics of the alloys. The experimental observations were also used to critically assess the predictive capability of thermodynamic database calculations. Despite the qualitative agreement observed between the experimental results and predictions for relatively simple quaternary and quinary model alloys, comparison of the results for higher order, multi-component γ/γ′–δ eutectic alloys reveals notable differences.

In Vivo Imaging of Tumor Cell Migration

The process of metastasis formation involves the migration and 3-D invasion of tumor cells from a primary tumor to distant sites. We propose that the dynamics of the migration and invasion process of magnetically labeled tumor cells can be monitored in animal models over prolonged time periods using magnetic resonance imaging (MRI). Human breast carcinoma cells (MB-MDA-231) were labeled with superparamagnetic Fe2O3 iron oxide nanoparticles coated with poly-L-lysine. The particles are readily taken up by cancer cells and stored in intracellular clusters. During cell division, the nanoparticle clusters are divided and split unevenly between daughter cells (mean partitioning fraction 0.85 to 0.15). Nanoparticles are non-toxic, are not degraded by the cell and remain stable for at least 3 weeks. In vitro collagen gel assays show no differences in contractile properties and invasion behavior of magnetically labeled vs. non-labeled tumor cells. MRI of cells suspended in agarose gave a detection limit of the spin-spin-relaxation-rate above the agar background of approximately 70 cells per 1 mm3. The minimal detection volume of tumor cells in agarose was 25 μl. Detection limit and minimal volume were verified by injecting labeled cancer cells in mice. Spin-spin-relaxation-weighted (T2-weighted) and susceptibility-weighted images show a rapid relaxation behavior and pronounced phase shifts in the vicinity of the injection area compared to control scans. These studies demonstrate the feasibility of the method for long-term observation of cancer cell migration in vivo with MRI.

Inhibitory Effects of Saussurea involucrata. Against Melanogenesis of Mouse-Derived Melanocyte Cells

Extracts and fractions from the aerial parts of herbal materials of Saussurea involucrata. Kar et Kir ex Maxim (Compositae) were investigated for their whitening activity against mouse-derived immortalized melanocyte cell line. The extract of wild herbs (FS2) possessed a better inhibition (28.2% growth) against melanin cells than that (46.7%) of cultivated herbs (FS1). The whole extracts and middle-polar partitioning fraction show the inhibitory effects, whereas the water-soluble parts show a poor activity in the same assay.

Erbium partitioning in a heavily doped transparent glass ceramic

An erbium-doped transparent glass ceramic, consisting of LaF3 nanocrystallites with a characteristic length of approximately 20 nm embedded in an aluminosilicate glass matrix and exhibiting infrared-to-green up-conversion, has been studied. The degree of erbium partitioning into the nanocrystallite phase was found using energy transfer coefficients determined from bulk Er3+:LaF3 samples. This transparent glass ceramic sample was found to have a partitioning fraction of 19 +/- 5%.

Simulating Organ Growth in Wheat Based on the Organ–Weight Fraction Concept

Quantifying dry matter partitioning into individual organs of plants is a key component for simulating crop growth and yield formation. This study was undertaken to develop a dynamic module of biomass partitioning over the entire duration of growth in wheat. The partitioning fraction of shoot or root was defined as the fraction of its dry weight in plant biomass, and partitioning fraction of green leaf, stem or ear as the fraction of its dry weight in shoot mass of wheat. The functional relationships of the partitioning fraction with physiological development time for the entire growth period were established, in which harvest index (HI) regulated partitioning fraction of ear to shoot biomass as a genetic parameter. The dry weight of individual organ was the product of the respective partitioning fraction and plant weight or shoot weight. Test of the model with the field experiment data sets involving different sowing dates, plant densities and nitrogen fertilization strategies indicated a good agreement between the predicted and observed values.

Combustion Organic Aerosol as Cloud Condensation Nuclei in Ship Tracks

Polycyclic aromatic hydrocarbons (PAHs) have been sampled in marine stratiform clouds to identify the contribution of anthropogenic combustion emissions in activation of aerosol to cloud droplets. The Monterey Area Ship Track experiment provided an opportunity to acquire data on the role of organic compounds in ambient clouds and in ship tracks identified in satellite images. Identification of PAHs in cloud droplet residual samples indicates that several PAHs are present in cloud condensation nuclei in anthropogenically influenced air and do result in activated droplets in cloud. These results establish the presence of combustion products, such as PAHs, in submicrometer aerosols in anthropogenically influenced marine air, with enhanced concentrations in air polluted by ship effluent. The presence of PAHs in droplet residuals in anthropogenically influenced air masses indicates that some fraction of those combustion products is present in the cloud condensation nuclei that activate in cloud. Although a sufficient mass of droplet residuals was not collected to establish a similar role for organics from measurements in satellite-identified ship tracks, the available evidence from the fraction of organics present in the interstitial aerosol is consistent with part of the organic fraction partitioning to the droplet population. In addition, the probability that a compound will be found in cloud droplets rather than in the unactivated aerosol and the compound’s water solubility are compared. The PAHs studied are only weakly soluble in water, but most of the sparse data collected support more soluble compounds having a higher probability of activation.

Correlations of the partitioning fraction of aerosols in clouds

Correlations of the partitioning fraction of aerosols in clouds

Erythrocyte membrane vesiculation: model for the molecular mechanism of protein sorting.

Budding and vesiculation of erythrocyte membranes occurs by a process involving an uncoupling of the membrane skeleton from the lipid bilayer. Vesicle formation provides an important means whereby protein sorting and trafficking can occur. To understand the mechanism of sorting at the molecular level, we have developed a micropipette technique to quantify the redistribution of fluorescently labeled erythrocyte membrane components during mechanically induced membrane deformation and vesiculation. Our previous studies indicated that the spectrin-based membrane skeleton deforms elastically, producing a constant density gradient during deformation. Our current studies showed that during vesiculation the skeleton did not fragment but rather retracted to the cell body, resulting in a vesicle completely depleted of skeleton. These local changes in skeletal density regulated the sorting of nonskeletal membrane components. Highly mobile membrane components, phosphatidylethanolamine- and glycosylphosphatidylinositol-linked CD59 with no specific skeletal association were enriched in the vesicle. In contrast, two components with known specific skeletal association, band 3 and glycophorin A, were differentially depleted in vesicles. Increasing the skeletal association of glycophorin A by liganding its extrafacial domain reduced the fraction partitioning to the vesicle. We conclude that this technique of bilayer/skeleton uncoupling provides a means with which to study protein sorting driven by changes in local skeletal density. Moreover, it is the interaction of particular membrane components with the spectrin-based skeleton that determines molecular partitioning during protein sorting.

Reducing work disability associated with rheumatoid arthritis: identification of additional risk factors and persons likely to benefit from intervention.

To study additional risk factors for rheumatoid arthritis (RA)-related work disability and to identify the groups of individuals at high risk and the potentially modifiable factors which place them at risk. A cross-sectional mail survey was conducted among 469 adults with RA. Work disability was defined as unemployment due to RA. A broad range of explanatory factors was examined, including sociodemographic, health, work, support given by others, and commuting difficulty. Employed and work-disabled subjects were compared by t-test and chi-square. Attributable fractions were calculated to assess the predictive value of factors. A recursive partitioning procedure identified individuals at varying risks for work disability, and their characteristics were defined. The risk factors joint pain and functional status, commuting difficulty, physical demands of the job, and disease duration were important predictors of work disability in both the attributable fraction and recursive partitioning analytic models. Having a professional or administrative job was protective, provided the salary earned was not low. Younger individuals with RA of shorter duration were placed at high risk by potentially modifiable factors. While older persons with RA of long duration were at high risk, modifiable factors could not be identified. Commuting difficulty, a previously overlooked factor, is an important predictor of RA work disability. Younger individuals with RA of relatively short duration can be placed at high risk by potentially modifiable factors including commuting difficulty, physically demanding jobs, greater joint pain and poor functional status, and nonprofessional/non-administrative jobs.