Function Of Partition Coefficient Research Articles

A Model correlating fluidity to alloy variables in hypoeutectic alloys

Mechanisms by which flow is choked are described. A criterion function for the choke of flow is proposed based on Darcy's law. Simple mathematical equations are derived to correlate grain size of an alloy to the permeability of its mushy zone, which is a function of the critical volume fraction of solid, gC, at which the flow is choked. Such a correlation gives rise to a simple analytical equation of gC to grain size. A two-parameter equation correlating grain size to phase diagram variables is then used in the analytical equations to describe fluidity as function of alloy variables. Experimental results obtained in well-controlled experiments are used to validate analytical relationships. Model predictions fit experimental data reasonably well. These simple analytical models indicate that fluidity decreases monotonically with increasing solidification interval of an alloy or modified constitutional supercooling parameter which is a function of liquidus slope, partition coefficient, and alloy composition.

A New Validity Index in Overlapping Clusters for Medical Images

Detecting automatically overlapping structures is a major issue in segmentation. In addition, the assessment of the quality of the clusters produced by fuzzy segmentation algorithms is one of the challenging tasks in segmentation process. To address this issue, a wide variety of functions called validity indexes have been proposed and developed. The overlap phenomenon constitute a source of failure for most of these indexes, in this context we propose a new cluster validity index VECS to recognize the optimal number of clusters adapted to the fuzzy c-means algorithm; based on the entropy, on the partition coefficient functions and on two criteria: the compactness within the classes and the inter-classes separation. We conducted experiments on medical imaging data sets, including simulated brain magnetic resonance imaging (MRI) and leukemia images. The experimental results reveal that, our VECS validity index outperform the other existing methods and has greater ability to identify the appropriate number of segments on high overlapped data sets.

A Novel Approach Canberra Measure Minimal Spanning Tree Using Fuzzy C-Means Based on Gaussian Function for Image Data Mining

Clustering analysis has been an emerging research issue in data mining due to its variety of applications. In recently, mathematical algorithm supported automatic segmentation system plays an important role in clustering of images. The fuzzy c-means clustering is a method of cluster analysis which aims to partition n data points into k-clusters. The conventional FCM-based algorithm considers no spatial content information, which means it sensitive to noise. Unsupervised techniques need to be employed, which can be based on minimal spanning tree generated by comparing spatial neighbourhood information, the MST based clustering algorithms have been widely used due to their ability to detect clusters with irregular boundaries. We propose an automatic fuzzy c-means initialization algorithm based on Canberra distance minimal spanning tree for the purpose of segmentation of medical images, where vertices and edges are labelled with multi-dimensional vectors. A Canberra distance measure based, construct the minimal spanning tree clustering algorithm. An efficient method for calculating membership and updating prototypes by minimizing the new objective function of Gaussian based fuzzy c-means. The algorithm uses a new cluster validation criterion based on the geometric property of data partition of the dataset in order to find the proper number of cluster at each level. In this algorithm to apply medical images to reduce the inhomogeneity and allow the labelling of a pixel to be influenced by the labels in its immediate neighbourhood and reduces the time complexity and better clustering results than the existing traditional minimal spanning tree algorithm. The performance of proposed algorithm has been shown with random data set, partition coefficient and validation function are used to evaluate the validity of clustering and then new cluster separation approach to optimal number of clustering. Also this paper compares the results of proposed method with the results of existing basic fuzzy c-means.

Variable selection in the functional linear concurrent model.

We propose methods for variable selection in the context of modeling the association between a functional response and concurrently observed functional predictors. This data structure, and the need for such methods, is exemplified by our motivating example: a study in which blood pressure values are observed throughout the day, together with measurements of physical activity, location, posture, affect or mood, and other quantities that may influence blood pressure. We estimate the coefficients of the concurrent functional linear model using variational Bayes and jointly model residual correlation using functional principal components analysis. Latent binary indicators partition coefficient functions into included and excluded sets, incorporating variable selection into the estimation framework. The proposed methods are evaluated in simulations and real-data analyses, and are implemented in a publicly available R package with supporting interactive graphics for visualization. Copyright © 2017 John Wiley & Sons, Ltd.

Chemical and isotopic composition of gases released by crush methods from organic rich mudrocks

We report on the composition of mudrock gases released under vacuum by ball-mill rock crushing and pressure induced fracturing. Nine core samples from organic rich Barnett Shale were used in this study. TOC content varies from 3.3–7.9%; thermal maturity varies from 0.58–2.07%Ro.Our results show that both thermal maturity and gas desorption contributes to changes in the CH4/CO2 ratio of gases released during rock crushing. CH4/CO2 ratios of these gases are lower at low thermal maturities and higher at high thermal maturities because more CH4 rich gas is generated at higher maturity levels. CH4/CO2 ratios decrease with longer rock crushing times because of the increase in the CO2 rich gas contribution. However, no obvious compositional fractionation occurs among C1, C2 and C3 of crushed-rock gas and C1/C2 and C2/C3 ratios remain nearly constant during crushing although these ratios are greatly increased overall when the level of thermal maturity is high. Gas geochemical parameters (C1/C2, C2/C3, and i-C4/n-C4) of released gas are good indicators of thermal maturation of organic rich shales. The CH4/CO2 ratio is a function of selectivity, partition coefficients and (possibly but less likely) sorption kinetics between CH4 and CO2 molecules in shales.Trends in released gas yield and gas chemistry during rock crushing relate to gas storage states and pore connectivity. The δ13C1, δ13C2 and δ13C3 values of gas released from particles of coarser size (> 250μm) are similar to values of gas produced from Barnett shales after hydraulic fracturing. CH4 dominated gas appears to be stored in larger connected pores and is therefore released during the initial stages of crushing. The carbon isotope values of methane, ethane and propane are heavier in the more thermally mature samples, suggesting that this released gas is representative of the gas chemistry of subsurface rocks. Retrieval of gas chemistry data from existing core samples provides information of great relevance for understanding deep shale gas reservoirs.

Solid effect in solvent extraction treatment of pre-treated oily sludge

Oil recovery from oily sludge generated from the petroleum industry has been investigated by solvent extraction using four organic solvents, cyclohexane, n-hexanol, n-butanol and kerosene. Special emphasis was placed on the effect of sludge (solid) concentration (CS) on the oil recovery efficiency (RO) and partition coefficient (KD). The KD was found to vary with CS. This phenomenon can be described as the “solid concentration effect” or “solid effect” (CS-effect). The CS-effect can be explained using the surface component activity (SCA) model that we developed previously. In this model, the activity coefficient of solid surface sites (fS) was proposed as a function of CS rather than unity because of interactions among solid particles. Based on the SCA model, we provide a CS-dependent function of partition coefficient (termed the SCA-partition coefficient function), in which the intrinsic (or thermodynamic) partition coefficient KD0 independent of CS can be simulated from extraction experimental data and can be used to characterize the extraction equilibrium. It was confirmed that the SCA-partition coefficient function could describe the CS-effect observed in our solvent extraction experiments accurately. In addition, the fS of the sludge was independent of the solvent in our tests and decreased with increasing temperature.

영상 분할을 위한 개선된 공간적 퍼지 클러스터링 알고리즘

FCM(fuzzy c-means)은 일반적으로 영상 분할에서 좋은 성능을 보인다. 하지만 공간 정보를 사용하지 않는 일반적인 FCM 알고리즘은 낮은 대비의 영상, 경계선이 뚜렷하지 않은 영상, 잡음이 포함된 영상의 분할에는 좋지 않은 성능을 보인다. 이와 같은 문제를 해결하기 위해 본 논문에서는 3x3 크기의 윈도우를 이용하여 윈도우 내의 중심 픽셀과 주변 픽셀간의 거리 정보를 소속 함수에 추가한 개선된 공간적 퍼지 클러스터링 알고리즘을 제안한다. 본 논문에서는 분할 계수, 분할 엔트로피, Xie-Bdni 함수와 같은 클러스터링 검증 함수를 이용하여 FCM 기반의 다양한 클러스터링 알고리즘과 제안한 알고리즘과의 성능을 비교하였다. 성능 평가 결과 제안한 알고리즘이 기존의 FCM기반의 클러스터링 알고리즘보다 클러스터링 검증 함수에서 성능이 우수함을 확인 할 수 있었다. Conventional fuzzy c-means (FCM) algorithms have achieved a good clustering performance. However, they do not fully utilize the spatial information in the image and this results in lower clustering performance for images that have low contrast, vague boundaries, and noises. To overcome this issue, we propose an enhanced spatial fuzzy c-means (ESFCM) algorithm that takes into account the influence of neighboring pixels on the center pixel by assigning weights to the neighbors in a <TEX>$3{\times}3$</TEX> square window. To evaluate between the proposed ESFCM and various FCM based segmentation algorithms, we utilized clustering validity functions such as partition coefficient (<TEX>$V_{pc}$</TEX>), partition entropy (<TEX>$V_{pe}$</TEX>), and Xie-Bdni function (<TEX>$V_{xb}$</TEX>). Experimental results show that the proposed ESFCM outperforms other FCM based algorithms in terms of clustering validity functions.

The effect of sorbent concentration on the partition coefficient of pollutants between aqueous and particulate phases

During studying the distribution of pollutants between the aqueous and particulate phases, an anomalous Cs-effect phenomenon, namely, the experimentally measured partition coefficient (Kp) value of a given system decreased with increasing the sorbent concentration (Cs), was observed in a number of adsorption systems. Classical Langmuir model cannot predict the Cs-effect. In this paper, a surface component activity (SCA) model was proposed, which suggests that surface component (adsorption site or adsorbed solute) activity coefficient is a function of Cs because of the existence of adsorbent particle–particle interactions. A semi-empirical Cs-dependent function of partition coefficient was derived, and it can predict the Cs-dependence of partition coefficient for both organic compounds and heavy metals.

High oxygen breathing improves inhomogeneities of ventilation-perfusion distributions in acutely injured lungs

Using twenty-five mongrel dogs either with or without alveolar flooding induced by oleic acid administration, the effects of high oxygen breathing (60% O2) on ventilation--perfusion (VA/Q) distributions in the lungs were systematically investigated. VA/Q distributions were examined by multiple inert gas elimination technique, from which the VA/Q values describing mean positions of perfusion (Q) and ventilation (VA) distributions against the VA/Q axis were calculated (mean Q and mean VA). As the first measure of dispersion for VA/Q distribution, the log standard deviation was estimated (log SD (Q) and logSD (VA)). As the second measure of dispersion, the area under the curve, constructed by plotting inert gas arterial-to-alveolar partial pressure differences as a function of blood-gas partition coefficient, was calculated (aAD area). High oxygen breathing slightly enhanced the dispersion of VA/Q distributions in the normal dogs but decreased that in the dogs injured with oleic acid. Therefore, we concluded that high oxygen breathing worsened the inhomogenieties of VA/Q distributions in normal lungs but did improve those in acutely injured lungs.

Development and application of an oil toxicity and exposure model, OilToxEx

An oil toxicity and exposure model (OilToxEx) was developed and validated for estimation of impacts to aquatic organisms resulting from acute exposure to spilled oil. Because oil exposure is shorter than the time required for equilibrium between the organism and the water to be reached, the time and temperature dependence of toxicity is addressed. Oil toxicity is a function of aromatic composition and the toxicity of individual aromatics in the mixture. Lethal concentration to 50% of exposed organisms (LC50), as a function of octanol-water partition coefficient (Kow), and an additive model are used to estimate the toxicity of monoaromatic and polycyclic aromatic hydrocarbon mixtures in water-soluble fractions (WSF) and oil-in-water dispersions (OWD) of oil. The toxicity model was verified by comparison with oil bioassay data where the exposure concentrations of aromatics were measured. The observed toxicity in the bioassays could be accounted for by the additive narcotic effects of the dissolved aromatics in the exposure media. Predicted LC50s were compared to those calculated from measured concentrations after spills to verify the exposure model for field conditions. These results indicate that the additive toxicity and exposure model may be used to estimate toxicity of untested oils and spill conditions.

Solute trapping in Cahn–Hilliard diffusion equation

We solve analytically the one-dimensional Cahn–Hilliard diffusion equation for a dilute alloy, and calculate steady-state concentration profiles across the solid/liquid interface as a function of equilibrium partition coefficient k e and interface velocity. The calculated partition coefficient k reproduces correctly limiting behavior in both low and high interface velocity limits: at low interface velocity k→ k e, and at high interface velocity k→1. This calculation also predicts that partitionless solidification occurs at higher interface velocity in alloys with smaller equilibrium partition coefficient, which is in agreement with the previously reported experimental results by Smith and Aziz.

Study of Interaction and Distribution of Mixed System of Anionic and Nonionic Surfactants Between Toluene and Water

ABSTRACT We determined the concentrations of petroleum sultanate and labelled AP type surfactants under the distributions of petroleum sultanate and labelled AP type surfactants alone and their mixed system to using HPLC and radiosoptic tracer. The interaction between the above two kinds of surfactants in the partitioning process was described quantitively under CMC using the formula related to partition coefficient and Thermodynamic functions. It was found that the interaction between petroleum sultanate and labelled Ap211 was the strongest interaction among the petroleum sultanates and hi helled A P type surfactants or various HLB.

Effect of partition coefficient, permeability surface product, and radioisotope on the signal-to-noise ratio in PET functional brain mapping: a computer simulation.

In this work we use a computer simulation to estimate the magnitude of improvement in the signal-to-noise ratio of PET functional brain mapping studies as a function of partition coefficient and permeability surface product for O-14, F-17, and O-15 labeled flow tracers. A model for signal-to-noise ratio is derived from the Kety model for inert diffusible blood flow tracers. The results of the simulation suggest that moderate increases in partition coefficient and permeability surface product compared with water would lead to an increase in signal-to-noise ratio of a factor of about 3.

Alcohols induce rapid depletion of intracellular free Mg 2+ in cerebral vascular muscle cells: relation to chain length and partition coefficient

Acute effects of a series of alcohols (methanol, ethanol, n-butanol) on intracellular free magnesium concentration ([Mg 2+] i in canine cerebral vascular smooth muscle cells was studied using mag-fura-2 and digital imaging microscopy. In 1.2 mM [Mg 2+] o, basal [Mg 2+] i was 500 ± 30 μM. Exposure of cells to a low concentration (25 mM) of ethanol, but not methanol, for only 30 s resulted in significant loss of [Mg2 2] i. Exposure to 100 mM methanol, ethanol, and butanol for 30 s resulted in a relative order of potency for [Mg 2+] i depletion, where butanol ⪢ ethanol > methanol. The heterogeneous and relative subcellular compartmented concentrations of [Mg 2+] i, where perinuclear > nuclear ⪢ peripheral (cytosolic) region, was not significantly altered by the alcohols. The degree of cellular depletion of [Mg 2+] i; was directly a function of each alcohol's partition coefficient and chain length. The latter is suggestive of the probability that alcohols promote intracellular depletion of Mg 2+ by partitioning in membranes and disordering lipid bilayers.

Sorption equilibria for trichloroethene on algae

The sorption of chlorinated solvents by algae can remove the solvents from natural waters and wastewaters treated in stabilization lagoons and other phototrophically active treatment processes. The equilibrium sorption of 14C-labeled trichloroethene (TCE) to three species of algae— Chlorella vulgaris, Scenedesmus quadricauda and Selenastrum capricornutum—was studied in batch reactors in which no biotransformations occurred. The sorption density was nonlinear with respect to equilibrium TCE concentration. The Freundlich isotherm, Q = KC n , successfully described the sorption equilibria, and n was greater than 1 for all three species. Thus, the apparent bioconcentration factor (BCF) increased with increasing TCE concentrations. Empirical correlations that predict the BCF as a function of the compound's octanol-water partition coefficient gave BCF values about one order of magnitude lower than shown by these experiments with algae. The content and distribution of lipids within the algae appear to cause substantially greater sorption by algae than by other forms of organic solids.

Rectilinear partition coefficient function of REE pertaining to the formation of basaltic rocks from the New Georgia Group, the Solomon Islands.

Nine basaltic rocks from the New Georgia Group, the Solomon Islands, have been analyzed for REE, Ba and Sr abundances, Sr and Nd isotopic ratios, and major element compositions. Nd and Sr isotopic ratios of four olivine basalts and two picrite basalts fall in restricted ranges, suggesting that these rocks have a common source. REE patterns of six of these basaltic rocks have the following features: (1) The patterns have no intersection with each other, (2) All of the patterns possess a common fine structure of convex curve around Nd-Gd-Dy, and (3) Inclination of light REE span increases with increase of REE concentration. REE pattern analysis of the basalts leads to inferences that (A) a linear REE partition coefficient function with a sharp break at Ho has operated in the generation of the olivine basalts by the Rayleigh fractional crystallization of a picrite basalt magma, and (B) the absolute magnitudes of the partition coefficients did not change substantially during the magmatic differentiation.

Structure-toxicity relationship of aliphatic nitriles

Acute toxicity, in vitro metabolism and structure-toxicity relationship of aliphatic mononitriles were examined in mice pretreated with carbon tetrachloride (CCl 4). The LD 50 in mice pretreated with CCl 4 (LD 50-CCl 4) was increased in most nitriles compared to that in untreated animals (LD 50-cont.) with different degrees among compounds. Microsomal metabolism of nitriles to CN − was completely inhibited when microsomes were prepared from livers of mice pretreated with CCl 4. Log (1/LD 50-CCl 4) was a linear function of partition coefficient, log P, i.e., log (1/LD 50-CCl 4) = −0.371 log P-0.152, and the equation was statistically significant ( P < 0.01), provided aceto- and 3-hydroxypropionitrile were omitted from the analysis. These two compounds seem to be different from the others in exerting the biological effect.

Alternative models for describing the bioconcentration of organics in fish

AbstractThe accumulation of organic residues in fish is the result of competing rates of uptake and elimination, which can be modeled by pharmacokinetic techniques. Although first‐order kinetics are usually assumed, they are rarely verified. Models with biphasic, second‐order or Michaelis‐Menten kinetics may prove to be better choices, depending on exposure level and mode of elimination. The well‐known correlation between bioconcentration factor and partition coefficient (P) derives from separate correlations for the uptake and elimination rate constants with P. While such correlations appear to be linear in the range of log P = 2–5 for organics that are not metabolized, they sometimes fail at higher values of log P. A drug transport model is proposed to account for the “non‐ideal” bioconcentration of a variety of organics in fish. According to this model, uptake is a nonlinear function of partition coefficient, water solubility and membrane permeability.

Wholly compatible and complementary patterns of rare-earth elements in Quaternary volcanic rocks from Oshima-Oshima and Oshima-Kojima isles, Japan.

The REE abundances in one basalt and two andesites from Oshima-Oshima and -Kojima isles, Hokkaido, Japan, were determined precisely by mass-spectrometric stable isotope dilution technique. The abundance ratios between two distinct volcanic rocks, i.e., andesite (old somma) and basalt (young somma), from Oshima-Oshima isle show a linear function of atomic number, with breaks at Z = 68 and between 63 and 64. This can be interpreted as implying that the andesite and the basalt studied stand in a mutually conjugate relationship as possible, previously concurrent liquid and solid phases. Employing the abundance ratio function as an effective bulk partition coefficient function, the retrogressive fractionation was theoretically followed back by calculation for different FW* values. The results of calculation suggest that there were two stages concerning the relevant bulk partition coefficient functions for the development of the andesite in question and that the terrace-shaped bulk partition coefficient function with a break at Z = 67 (Ho) worked prior to the tri-segment partition coefficient function obtained directly from the abundance ratio between the andesite and the basalt.

ALTERNATIVE MODELS FOR DESCRIBING THE BIOCONCENTRATION OF ORGANICS IN FISH

The accumulation of organic residues in fish is the result of competing rates of uptake and elimination, which can be modeled by pharmacokinetic techniques. Although first-order kinetics are usually assumed, they are rarely verified. Models with biphasic, second-order or Michaelis-Menten kinetics may prove to be better choices, depending on exposure level and mode of elimination. The well-known correlation between bioconcentration factor and partition coefficient (P) derives from separate correlations for the uptake and elimination rate constants with P. While such correlations appear to be linear in the range of log P = 2–5 for organics that are not metabolized, they sometimes fail at higher values of log P. A drug transport model is proposed to account for the “non-ideal” bioconcentration of a variety of organics in fish. According to this model, uptake is a nonlinear function of partition coefficient, water solubility and membrane permeability.