Journal articles: 'Distribution/partition coefficient'

1

Davies, Matthew N., and Darren R. Flower. "A Benchmark Dataset Comprising Partition and Distribution Coefficients of Linear Peptides." Dataset Papers in Biology 2013 (May 16, 2013): 1–4. http://dx.doi.org/10.7167/2013/976758.

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Peptides have a dominant role in biology; yet the study of their physical properties is at best sporadic. Peptide quantitative structure-activity relationship (QSAR) lags far behind the QSAR analysis of drug-like organic small molecules. Traditionally, QSAR has focussed on experimentally determined partition coefficients as the main descriptor of hydrophobicity. A partition coefficient () is the ratio between the concentrations of an uncharged chemical substance in two immiscible phases: most typically water and an organic solvent, usually 1-octanol. A distribution coefficient () is the equivalent ratio for charged molecules. We report here a compilation of partition and distribution coefficients for linear peptides compiled from literature reports, suitable for the development and benchmarking of peptide and prediction algorithms.

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Baláž, Štefan, Anton Kuchár, Ernest Šturdík, Michal Rosenberg, Ladislav Štibrányi, and Dušan Ilavský. "Interphase distribution of 2-furylethylenes." Collection of Czechoslovak Chemical Communications 50, no. 8 (1985): 1642–47. http://dx.doi.org/10.1135/cccc19851642.

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The distribution kinetics of 35 2-furylethylene derivatives in two-phase system 1-octanol-water was investigated. The transport rate parameters in direction water-1-octanol (l1) and backwards (l2) are partition coefficient P = l1/l2 dependent according to equations l1 = logP - log(βP + 1) + const., l2 = -log(βP + 1) + const., const. = -5.600, β = 0.261. Importance of this finding for assesment of distribution of compounds under investigation in biosystems and also the suitability of the presented method for determination of partition coefficients are discussed.

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3

Yang, Shi Ruo, and Dan Qing Chen. "Railway Steel Truss Coefficient of Lateral Force Distribution." Advanced Materials Research 304 (July 2011): 359–65. http://dx.doi.org/10.4028/www.scientific.net/amr.304.359.

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This paper illustrates the internal force calculation of the railway steel truss girder under the action of lateral load q by using the finite element method for truss segment. Load q is distributed with partition coefficients a1, a2 respectively on the top and bottom longitudinal bracing in conventional way and calculated as planar articulate. When two forces calculated respectively by using the spatial analysis and planar structure method are equal, lateral force distribution coefficient a1, a2 can be obtained. In the end of this paper we take examples of simple through beam of 48m, 64m, 80m, 144m, 192m, continuous through beam of 2×64m,3×64m, dual continuous deck beam of 2×64m and dual simple through beam of 64m and get the partition coefficient of the floor system plane, 0.77, and the other plane is 0.39.

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Schwarzenbach, R. P., and J. Westall. "Sorption of Hydrophobic Trace Organic Compounds in Groundwater Systems." Water Science and Technology 17, no. 9 (1985): 39–55. http://dx.doi.org/10.2166/wst.1985.0081.

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Factors influencing the subsurface sorption behavior of neutral and ionizable trace organic compounds are discussed. At equilibrium, the sorption of a neutral hydrophobic organic compound can be expressed by a simple partition coefficient. Partition coefficients, and thus retardation factors, may be estimated from the octanol/water partition coefficient of the compound and the organic carbon content of the aquifer material, if the organic carbon content exceeds 0.1%. For ionizable (anionic) hydrophobic compounds (represented by chlorinated phenols), the distribution ratio depends on both the pH and ionic strength of the aqueous phase, in contrast to the partitioning model for neutral compounds in which the composition of the aqueous phase is relatively unimportant.

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5

Berthod, Alain, and Nazim Mekaoui. "Distribution ratio, distribution constant and partition coefficient. Countercurrent chromatography retention of benzoic acid." Journal of Chromatography A 1218, no. 36 (2011): 6024–30. http://dx.doi.org/10.1016/j.chroma.2010.12.027.

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6

Aryani, Ni Luh Dewi. "PENETAPAN NILAI PARAMETER LIPOFILISITAS (LOG P, JUMLAH TETAPAN  HANSCH DAN TETAPAN f REKKER) ASAM PIPEMIDAT." Sains & Teknologi 1, no. 2 (2019): 17. http://dx.doi.org/10.24123/jst.v1i2.2224.

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Lipophilicity is the most often used physicochemical property in quantitative structure-activity relationships (QSAR) studies because it is related to the absorption across biological membrane and the distribution between body fluid and lipid-rich phase of drugs. Its quantitative descriptor is the octanol-water partition coefficient (usually expressed as log P). The 1-octanol-water partition coefficient of pipemidic acid was determined by an experimental using the shake-flask method and by calculating from p Hansch and f Rekker constant. The values of logarithmic intrinsic partition coefficient (IPC) and apparent partition coefficient (APC) of pipemidic acid were -2,03 ± 0,25 and -3,932 ± 0,25. The values of logarithmic partition coefficient, which were obtained by calculating of p Hansch and f Rekker constant were -1,65 and -1,981, respectively.

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Mäntylä, M., J. Perkkiö, and J. Heikkonen. "Partition Coefficient Ratios and Tumour Perfusion Studied with 85mKr and 133Xe." Nuklearmedizin 26, no. 06 (1987): 253–57. http://dx.doi.org/10.1055/s-0038-1628899.

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The relative partition coefficients of krypton and xenon, and the regional blood flow in 27 superficial malignant tumour nodules in 22 patients with diagnosed tumours were measured using the 85mKr- and 133Xe-clearance method. In order to minimize the effect of biological variables on the measurements the radionuclides were injected simultaneously into the tumour. The distribution of the radiotracers was assumed to be in equilibrium at the beginning of the experiment. The blood perfusion was calculated by fitting a two-exponential function to the measuring points. The mean value of the perfusion rate calculated from the xenon results was 13 ± 10 ml/(100 g-min) [range 3 to 38 ml/(100 g-min)] and from the krypton results 19 ± 11 ml/(100 g-min) [range 5 to 45 ml/(100 g-min)]. These values were obtained, if the partition coefficients are equal to one. The equations obtained by using compartmental analysis were used for the calculation of the relative partition coefficient of krypton and xenon. The partition coefficient of krypton was found to be slightly smaller than that of xenon, which may be due to its smaller molecular weight.

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8

Liu, Chi-Hsien, Hao-Che Chiu, Wei-Chi Wu, Soubhagya Laxmi Sahoo, and Ching-Yun Hsu. "Novel Lutein Loaded Lipid Nanoparticles on Porcine Corneal Distribution." Journal of Ophthalmology 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/304694.

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Topical delivery has the advantages including being user friendly and cost effective. Development of topical delivery carriers for lutein is becoming an important issue for the ocular drug delivery. Quantification of the partition coefficient of drug in the ocular tissue is the first step for the evaluation of delivery efficacy. The objectives of this study were to evaluate the effects of lipid nanoparticles and cyclodextrin (CD) on the corneal lutein accumulation and to measure the partition coefficients in the porcine cornea. Lipid nanoparticles combined with 2% HPβCD could enhance lutein accumulation up to209.2±18(μg/g) which is 4.9-fold higher than that of the nanoparticles. CD combined nanoparticles have 68% of drug loading efficiency and lower cytotoxicity in the bovine cornea cells. From the confocal images, this improvement is due to the increased partitioning of lutein to the corneal epithelium by CD in the lipid nanoparticles. The novel lipid nanoparticles could not only improve the stability and entrapment efficacy of lutein but also enhance the lutein accumulation and partition in the cornea. Additionally the corneal accumulation of lutein was further enhanced by increasing the lutein payload in the vehicles.

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9

Mochalski, Paweł, Julian King, Alexander Kupferthaler, Karl Unterkofler, Hartmann Hinterhuber, and Anton Amann. "Human Blood and Plasma Partition Coefficients for C4-C8 n-alkanes, Isoalkanes, and 1-alkenes." International Journal of Toxicology 31, no. 3 (2012): 267–75. http://dx.doi.org/10.1177/1091581812442689.

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Human blood:air and plasma:air partition coefficients for C4-C8 n-alkanes, isoalkanes, and 1-alkenes were determined using multiple headspace extraction coupled with solid phase microextraction and gas chromatography. Mean blood:air partition coefficients expressed in the form of dimensionless blood-to-air concentration ratio (g/mLb/g/mLa) were 0.183, 0.416, 1.08, 2.71, and 5.77 for C4-C8 n-alkanes; 0.079, 0.184, 0.473, 1.3, and 3.18 for C4-C8 isoalkanes; and 0.304, 0.589, 1.32, 3.5, and 7.01 for C4-C8 1-alkenes, respectively (n = 8). The reported partition coefficient values increased exponentially with boiling points, molecular weights, and the carbon atoms in the particle. The solubility of 1-alkenes in blood was higher than in plasma, whereas the blood:air and plasma:air partition coefficients of n-alkanes and isoalkanes did not differ significantly. Consequently, additional interactions of 1-alkenes with whole blood seem to occur. The presented findings are expected to be particularly useful for assessing the uptake, distribution, and elimination of hydrocarbons in human organism.

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Aliyu, Ahmed Sidi, Nuhu Musa Waziri, Hadiza Liman Mohammad, and Mohammed Abubakar Mohammed. "Partition behaviour of iron and zinc in the catchment alluvial sediments of River Gbako flood plains around Baddegi, central Bida basin, Nigeria." Scientia Bruneiana 18, no. 2 (2020): 32–39. http://dx.doi.org/10.46537/scibru.v18i2.94.

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Partition behaviors of iron (Fe) and zinc (Zn) were studied in the alluvial sediments of River Gbako floodplains around Baddegi using empirical formulas. The samples were cored from three pits locations (TR-1, TR-2, and TR-3). Particle size distribution and geochemical analysis were performed. Particle size distribution results indicated that the sediments are sand dominated. They have more than 50% sand with smaller percentages of clay and silt. Average partition coefficient values of Fe in the sediments are 1.02, 0.83, and 0.88 for TR-1, TR-2, and TR-3, respectively, and for Zn are 1.02, 0.95, and 0.83, for TR-1, TR-2 and TR-3, respectively. The average velocities of Fe mobilization in the sediments are 0.08 m/day, 0.07 m/day and 0.09 m/day for TR-1, TR-2 and TR-3, respectively, and for Zn mobilization are 0.07 m/day, 0.07 m/day and 0.09 m/day, for TR-1, TR-2, and TR-3, respectively. The metals were preferentially partitioned in the sediments than the water percolating through them, with average hydraulic conductivity (K) of 4.2 m/day. The partition behavior of the metals is used to explain contaminant transportation in the alluvial sediments of the River Gbako floodplains around Baddegi and the principle behind groundwater purification in the shallow alluvial aquifers of these floodplains.  Index Terms: Partition coefficient, hydraulic conductivity, alluvial sediments, floodplain, Nigeria

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11

Wu, Yu, Fu Sheng Pan, Bin Jiang, Xiao Ke Li, and Qi Tao Fu. "Solute Distribution and Segregation during Solidification of Mg-6Al Alloys." Materials Science Forum 686 (June 2011): 310–15. http://dx.doi.org/10.4028/www.scientific.net/msf.686.310.

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Solute distribution and segregation in solidification will largely influence the characteristics of solidification microstructure and precipitation order of the second phase. In this paper, the solid-liquid interfaces of Mg-6Al alloy with different temperature were obtained by rapid quenching based on a special melting furnace and were analyzed using scanning electron microscopy, energy diffraction spectrum and Thermo-Calc calculation tool. It was found that the primary α-Mg phase grew through cystiform dendrite interface. The solute partition coefficient and dendrite segregation rate for Al in the solid phase of Mg-6Al alloy basically had little change with decrease of the temperature. The dendrite become fine, and the solute partition coefficient decreased, while dendrite segregation rate of Al in the dendrite boundaries increased, because of the addition of Zn to Mg-6Al alloys.

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12

Heirwegh, K. P. M., J. A. T. P. Meuwissen, M. Vermeir, and H. De Smedt. "Liposomes as carriers of poorly water-soluble substrates: linear modelling of membrane systems with catalytic or binding sites of different facedness. Significance of experimental membrane partition coefficients and of kinetic and equilibrium parameters." Biochemical Journal 254, no. 1 (1988): 101–8. http://dx.doi.org/10.1042/bj2540101.

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1. A multiphasic modelling approach to systems containing membrane-bound receptors or catalytic sites and a liposomal preparation as a substrate carrier is described. Kinetic expressions are derived for a single-substrate enzymic reaction operating at constant liposome concentration or at a fixed substrate/liposome concentration ratio. 2. The assumption that accumulation of exchangeable components into the phospholipid bilayers can be described by linear bulk-phase partition leads to simple relationships between the initial reaction rate and (a) two kinetic coefficients (V and K'm), (b) the partition coefficients of the solutes for the lipid compartments of the membrane (Pms) and liposomal preparations (P1s) and (c) the total concentrations of substrate, membrane lipid and liposomal lipid. K'm is called the effective Michaelis constant. 3. For correct estimation of the coefficients V, K', Pms and P1s extrapolation to zero lipid concentration is required. 4. The distinction is introduced between hydrophilic and hydrophobic aqueous-faced sites, lipid-faced sites and mixed sites, i.e. sites overlapping an aqueous and a lipid region. For hydrophilic aqueous-faced sites K'm is equal to the true Km and for the other types of site to Km/Ps. For lipid-faced and for mixed sites Ps corresponds to the membrane partition coefficient Pms. For binding of homologous compounds to a hydrophobic aqueous-faced binding pocket Ps is the incremental site partition coefficient Pbss, which takes into account the energetic contribution to the binding process due to the hydrophobic tail of the ligands. 5. K'm accounts for any effects due to the facedness and nature of the enzymic sites. The dependence of the systems on the size of the lipidic partition compartment(s) is expressed exclusively by a distribution function F.6. When enzyme assays are performed with a series of chemically different substrates containing the same catalytically sensitive group, independence of K'm from partition indicates a hydrophilic aqueous-faced binding site. For the low-molecular-mass members of the homologous series a linear increase in -log (K'm) with the logarithm of the partition coefficient will be observed with any of the other site types considered 7. Equilibrium relationships for binding of a ligand to a membrane-bound receptor are also derived. 8. The significance of experimental membrane partition coefficients is discussed.

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13

S. Bharate, Sonali, Vikas Kumar, and Ram A. Vishwakarma. "Determining Partition Coefficient (Log P), Distribution Coefficient (Log D) and Ionization Constant (pKa) in Early Drug Discovery." Combinatorial Chemistry & High Throughput Screening 19, no. 6 (2016): 461–69. http://dx.doi.org/10.2174/1386207319666160502123917.

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14

Czeszak, Aleksandra, Matylda Resztak, Andrzej Czyrski, and Izabela Nowak. "Determination of the partition coefficient of isoquinoline alkaloids from Chelidonium majus by reversed phase thin layer chromatography." New Journal of Chemistry 44, no. 18 (2020): 7484–89. http://dx.doi.org/10.1039/d0nj00307g.

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Determination of the partition coefficient (log P) of alkaloids by the RP-TLC method at different pH values. Distribution coefficient (log D) values were calculated. The investigated chlorides were found to be the most lipophilic of the compounds studied.

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15

Kaliszan, R. "Brain/blood distribution described by a combination of partition coefficient and molecular mass." International Journal of Pharmaceutics 145, no. 1-2 (1996): 9–16. http://dx.doi.org/10.1016/s0378-5173(96)04712-6.

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16

Chijiiwa, K., and W. G. Linscheer. "Distribution and monomer activity of cholesterol in micellar bile salt: effect of cholesterol level." American Journal of Physiology-Gastrointestinal and Liver Physiology 252, no. 3 (1987): G309—G314. http://dx.doi.org/10.1152/ajpgi.1987.252.3.g309.

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Despite the fact that uptake of cholesterol by the enterocyte occurs as a monomer from the intermicellar aqueous phase in equilibrium with micelle, the cholesterol monomer concentration in the aqueous phase and the partition coefficient between intermicellar aqueous phase and micellar aggregate have not been clarified. The present study deals with the distribution of cholesterol and monomer activity in constant bile salt-fatty acid micellar solutions with different cholesterol concentrations. In addition, uptake of cholesterol from these micellar solutions into rat jejunum was studied using everted sacs. Cholesterol monomer concentration in the aqueous phase increased linearly with the concentration of cholesterol in the micellar solution. Partition coefficient of cholesterol between the aqueous phase surrounding micelle and micellar aggregate was essentially constant at any cholesterol level (K = 3 X 10(-2)). Cholesterol monomer activities were linearly proportional to the cholesterol concentrations in the micellar solutions and correlated well with the rate of cholesterol uptake. It is concluded from these experiments that a partitioning phenomenon determines cholesterol monomer concentrations in the intermicellar aqueous phase from which the cholesterol is absorbed. After disappearance of the cholesterol monomers from the aqueous phase, these monomers are replaced by a shift of monomers from the intramicelle to intermicellar aqueous phase, under constant partition coefficient between extra- and intramicelle. The bile salt micelle provides a huge reservoir for partitioning of cholesterol monomers.

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17

FernÃ¡ndez-Pumarega, Alejandro, BelÃ©n MartÃn-Sanz, Susana AmÃ©zqueta, Elisabet Fuguet, and MartÃ RosÃ©s. "Estimation of the octanol-water distribution coefficient of basic compounds by a cationic microemulsion electrokinetic chromatography system." ADMET and DMPK 8, no. 1 (2020): 98–112. http://dx.doi.org/10.5599/admet.760.

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The octanol-water partition coefficient (Po/w), or the octanol-water distribution coefficient (Do/w) for ionized compounds, is a key parameter in the drug development process. In a previous work, this parameter was estimated through the retention factor measurements in a sodium dodecyl sulfate (SDS) - microemulsion electrokinetic chromatography (MEEKC) system for acidic compounds. Nonetheless, when ionized basic compounds were analyzed, undesirable ion pairs were formed with the anionic surfactant and avoided a good estimation of log Do/w. For this reason, an alternative MEEKC system based on a cationic surfactant has been evaluated to estimate Po/w or Do/w of neutral compounds and ionized bases. To this end, it has been characterized through the solvation parameter model (SPM) and compared to the octanol-water partition system. Results pointed out that both systems show a similar partition behavior. Hence, the logÂ Po/w of a set of neutral compounds has been successfully correlated against the logarithm of the retention factor (log k) determined in this MEEKC system. Then, the log Do/w of 6 model bases have been estimated at different pH values and they have been compared to data from the literature, determined by the reference shake-flask and potentiometric methods. Good agreement has been observed between the literature and the estimated values when the base is neutral or partially ionized (up to 99 % of ionization).

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18

Petit, Sabine, Fabien Baron, and Alain Decarreau. "Controls on tetrahedral Fe(III) abundance in 2:1 phyllosilicates—Discussion." American Mineralogist 106, no. 9 (2021): 1534–35. http://dx.doi.org/10.2138/am-2021-7865.

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Abstract Cuadros et al. (2019) used a wide range of data from dioctahedral and trioctahedral Fe3+-bearing, 2:1 phyllosilicates to propose a model describing how tetrahedral occupancy by Fe3+ takes place in both dioctahedral and trioctahedral 2:1 phyllosilicates. The partition coefficient approach (Decarreau and Petit 2014) focusing on the distribution of Al3+ and Fe3+ between octahedral and tetrahedral sites of dioctahedral smectites has been disregarded in the study of Cuadros et al. (2019). This approach was applied here on the set of data from Cuadros et al. (2019). The partition coefficient value linked to the distribution of Al3+ and Fe3+ between octahedral and tetrahedral sites determined from natural and synthetic dioctahedral smectites applies well to trioctahedral phyllosilicates too. Data from synthetic iron-rich 2:1 smectites also fit well with both Cuadros et al. (2019) and Decarreau and Petit (2014) models.

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Radonic, Jelena, Mirjana Vojinovic-Miloradov, Maja Turk-Sekulic, Jelena Kiurski, Maja Djogo, and Dusan Milovanovic. "The octanol-air partition coefficient KOA as a predictor of gas-particle partitioning of polycyclic aromatic hydrocarbons and polychlorinated biphenyls at industrial and urban sites." Journal of the Serbian Chemical Society 76, no. 3 (2011): 447–58. http://dx.doi.org/10.2298/jsc100616037r.

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The main objectives of the research were to estimate the relationship between the gas-particle partition coefficient, Kp, and the octanol-air partition coefficient, KOA, of polycyclic aromatic hydrocarbons, PAHs, and polychlorinated biphenyls, PCBs, at industrial and urban sites in the Vojvodina region, to compare the obtained slopes and intercepts of the log vs. log KOA relations with the results of regression analyses reported in previous studies and to assess the consistency between the particle-bound fractions predicted by the KOA absorption model and the results obtained within field measurements. Fairly good log KP - log KOA correlations, with an average value of the correlation coefficients of 0.70, indicate that the partition coefficient KOA can be used as a prediction parameter of the gas-particle partitioning processes for both classes of compounds. The results of modelling the atmospheric distribution of PAHs using the KOA absorption model showed inconsistencies between the measured and predicted values of the particle-bound fraction, ?, of 1-2 orders of magnitude, while significantly higher discrepancies for PAHs in the Nap-Ace range were found. A similar variability of the measured/modelled ? values was obtained using the Junge-Pankow adsorption model, indicating the presence of particles enriched with PAHs. The conducted research showed that the KOA-based approach was less suitable for predicting the gas-particle partitioning of PCBs in urban and industrial sites, compared to the Junge-Pankow model.

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20

Decarreau, A., and S. Petit. "Fe3+/Al3+ partitioning between tetrahedral and octahedral sites in dioctahedral smectites." Clay Minerals 49, no. 5 (2014): 657–65. http://dx.doi.org/10.1180/claymin.2014.049.5.03.

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AbstractThe distribution of Al3+ and Fe3+ between octahedral and tetrahedral sites of dioctahedral smectites was shown to be controlled by a partition coefficient Kd(4/6) = [(Fe3+)4×(Al3+)6]/[(Fe3+)6×(Al3+)4]. The Kd(4/6) value is near 0.006 for natural dioctahedral smectites, formed between 2 and ~100°C, and near 0.0174 for smectites synthesized at 200°C. These Kd(4/6) values, obtained from both chemical and spectroscopic data, were consistent with those calculated using the ionic radii of cations and Brice’s model (Brice, 1975). The partition coefficient approach explained well why for natural and synthetic dioctahedral smectites no tetrahedral Fe3+ is detected when the total Fe3+ content is below 3 atoms per unit cell (24 oxygen atoms).

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21

Efremenko, Vasily, Roman Kussa, Ivan PETRYSHYNETS, et al. "Element partitioning in low-carbon Si2Mn2CrMoVNb TRIP-assisted steel in intercritical temperature range." Acta Metallurgica Slovaca 26, no. 3 (2020): 116–21. http://dx.doi.org/10.36547/ams.26.3.554.

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The present paper is aimed at the study of the kinetics of Mn, Si, Cr partitioning in 0.2wt%C-Si2Mn2CrMoVNb TRIP-assisted steel under the annealing at 770 oC and 830 oC to be within the intercritical temperature range. The work was fulfilled using SEM, EDX, dilatometry, and hardness measurements. It was found that under heating a redistribution of the alloying elements between ferrite and austenite took place. Specifically, silicon partitioned to ferrite while chromium diffused to austenite with distribution coefficient values of 1.12-1.21 (KSi) and 0.75-0.86 (KCr). Manganese was found to partition to a much greater extent resulting in a distribution coefficient of KMn=0.38-0.50 and 2.6 times higher concentration in austenite as compared to ferrite. As annealing temperature raised from 770 oC to 830 oC the elemental partitioning was accelerated, followed by the decrease in manganese content in austenite (by 1.44 time) and ferrite (by 1.34 time) caused by an increase in austenite volume fraction. Silicon featured uneven distribution within ferrite to be accumulated at the “martensite/ferrite” interface and near ferrite grain boundaries, while manganese was concentrated in MC carbides. The recommendation for annealing holding was formulated based on elemental partitioning kinetics.

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Klose, Matthias, Sarah Theiner, Hristo Varbanov, et al. "Development and Validation of Liquid Chromatography-Based Methods to Assess the Lipophilicity of Cytotoxic Platinum(IV) Complexes." Inorganics 6, no. 4 (2018): 130. http://dx.doi.org/10.3390/inorganics6040130.

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Lipophilicity is a crucial parameter for drug discovery, usually determined by the logarithmic partition coefficient (Log P) between octanol and water. However, the available detection methods have restricted the widespread use of the partition coefficient in inorganic medicinal chemistry, and recent investigations have shifted towards chromatographic lipophilicity parameters, frequently without a conversion to derive Log P. As high-performance liquid chromatography (HPLC) instruments are readily available to research groups, a HPLC-based method is presented and validated to derive the partition coefficient of a set of 19 structurally diverse and cytotoxic platinum(IV) complexes exhibiting a dynamic range of at least four orders of magnitude. The chromatographic lipophilicity parameters φ0 and Log kw were experimentally determined for the same set of compounds, and a correlation was obtained that allows interconversion between the two lipophilicity scales, which was applied to an additional set of 34 platinum(IV) drug candidates. Thereby, a φ0 = 58 corresponds to Log P = 0. The same approaches were successfully evaluated to determine the distribution coefficient (Log D) of five ionisable platinum(IV) compounds to sample pH-dependent effects on the lipophilicity. This study provides straight-forward HPLC-based methods to determine the lipophilicity of cytotoxic platinum(IV) complexes in the form of Log P and φ0 that can be interconverted and easily expanded to other metal-based compound classes.

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Zheng, Lei, Tingting Liu, En Xie, et al. "Partition and Fate of Phthalate Acid Esters (PAEs) in a Full-Scale Horizontal Subsurface Flow Constructed Wetland Treating Polluted River Water." Water 12, no. 3 (2020): 865. http://dx.doi.org/10.3390/w12030865.

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When used as highly produced chemicals and widely used plasticizers, Phthalate acid esters (PAEs) have potential risks to human life and the environment. In this study, to assess the distribution and fate of PAEs, specifically inside a full-scale horizontal subsurface flow constructed wetland, four PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and bis (2-ethylhexyl) phthalate (DEHP) were investigated. In effluent, PAEs concentration decreased 19.32% (DMP), 19.18% (DEP), 19.40% (DBP), and 48.56% (DEHP), respectively. Within the wetland, PAEs partitioned in water (0.18–1.12 μg/L, 35.38–64.92%), soil (0.44–5.08 μg/g, 1.02–31.33%), plant (0.68–48.6 μg/g, 0.85–36.54%), air and biological transformation (2.72–33.21%). The results indicated that soil and plant adsorption contributed to the majority of PAE removal, digesting DMP (19.32%), DEP (19.18%), DBP (19.40%), and DEHP (48.56%) in constructed wetlands. Moreover, the adsorption was affected by both octanol/water partition coefficient (Kow) and transpiration stream concentration factors (TSCF). This work, for the first time, revealed the partition and fate of PAEs in constructed wetlands to the best of our knowledge.

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24

Shea, Patrick J. "Role of Humified Organic Matter in Herbicide Adsorption." Weed Technology 3, no. 1 (1989): 190–97. http://dx.doi.org/10.1017/s0890037x00031614.

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Organic matter is the soil constituent most often associated with herbicide adsorption. Structural diversity makes humified organic material an ideal substrate for the adsorption of many pesticides, but variability in composition and distribution in situ complicates interpretation of its quantitative effect on adsorption. Variability in the adsorption distribution coefficient (KD) of a herbicide among soils often is due to differences in organic matter content and can be reduced by adjusting KDfor soil organic carbon content and computing the organic carbon partition coefficient (Koc). Koccan be estimated from the octanol-water partition coefficient (Kow) of organic compounds, but the correlation weakens as compound polarity increases. Kocalso can be correlated with aqueous solubility if a correction is made for the melting point of compounds that are solids at 25 C. Relative adsorption can be estimated from parachor and molecular connectivity indices; but corrections are needed for polar compounds, and correlations with KDor Kochave been variable. Such predictive methods may be useful for broad classification purposes, but accurate extrapolation generally requires site-specific adsorption measurements. Empirical models which accommodate the multiple regression of organic matter content and other soil properties such as clay content, pH, and cation exchange capacity on herbicide adsorption can increase accuracy, but interpretation may be restricted to a small number of sites.

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Thompson, G. M., and J. Malpas. "Mineral/melt partition coefficients of oceanic alkali basalts determined on natural samples using laser ablation-inductively coupled plasma-mass spectrometry (LAM-ICP-MS)." Mineralogical Magazine 64, no. 1 (2000): 85–94. http://dx.doi.org/10.1180/002646100549148.

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AbstractIn order to limit the range of possible differentiation mechanisms and the impact of these processes on the trace element signatures of igneous suites, it is important to be able to predict or model the compositional evolution of the primary and/or parental magmas. Part of the problem in understanding these relationships in basalts from ocean islands is the paucity of reliable trace element mineral/melt partition coefficients, particularly for undersaturated magmas. Consequently, we have measured mineral/groundmass partition coefficients for Rb, Sr, Y, Zr, Nb, Hf, Ta, Th and REE, in situ, in clinopyroxene, Fe-Ti oxides and olivine in primitive basalts from Rarotonga, Cook Islands using LAM-ICP-MS.Analyses of these mafic rocks show high concentrations of most incompatible trace elements (e.g. Sr, Th, Y, REE, etc.) in pyroxenes relative to the other phases, suggesting that fractionation of pyroxenes was the dominant factor in the distribution of these trace elements during crystal fractionation. In such cases, the highly incompatible elements (D <0.01) are Ba, Cs and Nb. Elements that could also be classified as strongly incompatible (D <0.1) are Rb, Ta and Th. The remaining trace elements have bulk partition coefficient values that range from ∼.0.1 up to ∼.0.8 (Sr, Hf, Zr, Y and REE). Magnetites incorporate greater amounts of Nb and Ta than the titanaugites, and any significant fractionation of magnetite would have affected the bulk distribution of Nb and Ta. The LREE have lower Kd values than other REE, with the HREE having Kd values close to unity. Consequently, with the separation of titanaugite an overall enrichment of REE in the residual liquid with an increase in the La/Yb ratio is produced.

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Fernández-Pumarega, Alejandro, Susana Amézqueta, Elisabet Fuguet, and Martí Rosés. "Feasibility of the estimation of octanol-water distribution coefficients of acidic drugs by microemulsion electrokinetic chromatography." ADMET and DMPK 6, no. 1 (2018): 55. http://dx.doi.org/10.5599/admet.6.1.510.

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Previous studies have shown that a microemulsion electrokinetic chromatography (MEEKC) system can estimate the logarithm of the octanol-water partition coefficient (log Po/w) of neutral solutes. In the present work, the applicability of the method to partially and fully ionized acids has been evaluated. Naproxen, a monoprotic acid, has been used as test solute. The retention factor (k) of this compound has been measured in MEEKC at several values of pH and the retention factor-pH profile has been established. As log Po/w correlates with log kMEEKC for neutral compounds, this correlation has been used to estimate the logarithm of the octanol-water partition coefficient of the neutral (log Po/w(HA)), and the fully ionized (log P o/w(A-)) forms of naproxen. Then, the logarithm of the octanol-water distribution coefficient (log Do/w) of the partially ionized form of the acid has been estimated. The comparison of the estimated values with the ones obtained experimentally using the classical procedures, such as the shake-flask method, shows differences under 0.4 log Do/w units either if the acid is partially ionized or in its neutral form in the most part of the pH range. However, the method overestimates the log Do/w of the highly (&gt;99.5 %) or fully ionized form of naproxen.

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Chen, Hao, Yingchi Mao, Longbao Wang, and Hai Qi. "Spatial-Temporal Features Based Sensor Network Partition in Dam Safety Monitoring System." Sensors 20, no. 9 (2020): 2517. http://dx.doi.org/10.3390/s20092517.

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Many various types of sensors have been installed to monitor the deformation and stress in the dam structure. It is difficult to directly evaluate the operation status of the dam structure based on the massive monitoring data. The sensor network is divided into multiple regions according to the design specifications, simulation data, and engineering experiences. The local results from sub-regions are integrated to achieve overall evaluation. However, it ignores the spatial distribution of sensors and the variation of time series, which cannot meet the real-time evaluation for the dam safety monitoring. If the network partitions can provide the preliminary foundation for analyzing the dynamic change laws of the dam’s working conditions in a real-way, we should consider the similarity of structure and stresses in the local region of the dam and the correlation among the monitoring data. A time-series denoising autoencoder (TSDA) is proposed to represent the spatial and temporal features of the nodes by compressing high-dimensional monitoring data. Then, a network partitioning algorithm (NPA) based on spatial-temporal features based on the TSDA is presented. The NPA ensures that the partition results can support the analysis of the physical change laws by introducing the auxiliary objective variable to optimize the network partition objective function. Experimental results on the public datasets and a real dataset from an arch dam demonstrate that the proposed network partition algorithm NPA can achieve better partition performance than TSDA+K-Means and TSDA+GMM. The NPA can improve the silhouette coefficient by 45.1% and 58.4% higher than the TSDA+K-Means and TSDA+GMM, respectively. The NPA can increase the Calinski-Harabaz Index by 30.8% and 61.6%, respectively.

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Rucki, M., and M. Tichý. "Partition Coefficient Kow of Benzene, Ethanol and Aniline in Benzene-ethanol and Aniline-benzene Mixtures and Coefficient of Distribution Kmix of these Mixtures." QSAR & Combinatorial Science 25, no. 4 (2006): 310–16. http://dx.doi.org/10.1002/qsar.200530007.

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Zhang, Ge, Sheng Nan Gao, Wen Ding Wei, and Qiu Jian Xu. "Proton Transfer Reaction - Mass Spectrometry Determination of the Emission Rate of Flavor Ingredients in Toothpastes." Applied Mechanics and Materials 299 (February 2013): 229–32. http://dx.doi.org/10.4028/www.scientific.net/amm.299.229.

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Under the experimental conditions, the headspace concentration of two flavor ingredients in toothpastes, limonene (C10H16) and menthone (C10H18O), was measured with proton transfer reaction - mass spectrometry (PTR-MS). Combined with the theoretical diffusion model and analytical solution, the partition coefficient and the emission rate of the two ingredients from toothpaste diluent to the circulated air were calculated. Theoretical Solutions of the distribution coefficients were obtained respectively as 0.00432 and 0.00418 for C10H16 and C10H18O. The corresponding simulated flavor concentration in headspace air Ca(t) had good agreement with the experimental values (R2 = 0.983 and 0.958 respectively). The exponential decay rate formulas for the two flavors were obtained from experimental data and the solution of the theoretical model.

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Salmon, Eric, David J. Brooks, Klaus L. Leenders, et al. "A Two-Compartment Description and Kinetic Procedure for Measuring Regional Cerebral [11C]Nomifensine Uptake Using Positron Emission Tomography." Journal of Cerebral Blood Flow & Metabolism 10, no. 3 (1990): 307–16. http://dx.doi.org/10.1038/jcbfm.1990.59.

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S-[11C]Nomifensine ( S-[11C]NMF) is a positron-emitting tracer suitable for positron emission tomography, which binds to both dopaminergic and noradrenergic reuptake sites in the striatum and the thalamus. Modelling of the cerebral distribution of this drug has been hampered by the rapid appearance of glucuronide metabolites in the plasma, which do not cross the blood–brain barrier. To date, [11C]NMF uptake has simply been expressed as regional versus nonspecific cerebellar activity ratios. We have calculated a “free” NMF input curve from red cell activity curves, using the fact that the free drug rapidly equilibrates between red cells and plasma, while glucuronides do not enter red cells. With this free [11C]NMF input function, all regional cerebral uptake curves could be fitted to a conventional two-compartment model, defining tracer distribution in terms of [11C]NMF regional volume of distribution. Assuming that the cerebellar volume of distribution of [11C]NMF represents the nonspecific volume of distribution of the tracer in striatum and thalamus, we have calculated an equilibrium partition coefficient for [11C]NMF between freely exchanging specific and nonspecific compartments in these regions, representing its “binding potential” to dopaminergic or noradrenergic uptake sites (or complexes). This partition coefficient was lower in the striatum when the racemate rather than the active S-enantiomer of [11C]NMF was administered. In the striatum of patients suffering from Parkinson's disease and multiple-system atrophy, the specific compartmentation of S-[11C]NMF was significantly decreased compared with that of age-matched volunteers.

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Asuero, Agustín G. "A Bilogarithmic Method for the Evaluation of Distribution Constant (Partition Coefficient) and Acidity Constants of Amphoteric Substances from Liquid-Liquid Distribution Measurements." Analytical Letters 25, no. 6 (1992): 1157–69. http://dx.doi.org/10.1080/00032719208020067.

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Onyeocha, Veronica O., O. D. Akpan, Ikejiofor A. Onuchukwu, and Maduabuchi A. Chidiebere. "The Dimerization Effects of Some Solutes on the Partition Coefficient k_D in Binary Immiscible Solvents." International Letters of Chemistry, Physics and Astronomy 80 (December 2018): 40–52. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.80.40.

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The dimerization of a solute dissolved in binary immiscible solvents shows that the value of the partition coefficient, kD of the solutes are influenced by the dimerization constant, K of the solute in one of the solvents according to the description: (C_X^A)/(C_X^B ) = kD + 2kD2KCxB where CxA and CxB are the concentrations of the solute x in the solvents A and B respectively. Both kD and K are parameters that predict the extent of beneficiation for most minerals. Also, kD is a fundamental parameter that determines the extent of solute recovery during solvent extraction. In this study, it is found that the order K kD and K kD are the effects for acetic and succinic acids respectively in the binary solvents composed of carbon tetrachloride/water and diethylether/water systems respectively. These results suggest that the distributions of these solutes in the solvents are accompanied by the formation of succinic anhydride which is more favoured than the dimerization of the acetic acid. Also, the changes in the values of distribution enthalpies, HD are corroborated to explain these experimental observations.

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Prakash Mishra, Shiv. "BUFFER SOLUTION BEHAVIOUR ON SOLUBILITY AND DISTRIBUTION COEFFICIENT OF BENZOIC ACID BETWEEN TWO IMMISCIBLE LIQUIDS." International Journal of Advanced Research 9, no. 06 (2021): 187–92. http://dx.doi.org/10.21474/ijar01/12999.

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The two immiscible solvents such as hydrophilic (water) and hydrophobic (benzene) have been reported for study of solubility and distribution of benzoic acid in it. The solubility of benzoic acid in water and in different acidic, neutral, and basic pH benzene-buffer solutions are analyzed by titrimetrically, and concentration of acid in both solvents by acid-base titration method. The shake-flask method are involved for where the partitioning or distribution coefficient of benzoic acid in these two solvents layer at room temperature (25Â°C). Observation reveals that, the benzoic acid solubility in g/100g for water is being 0.142Â±0.033 and at different buffer solutions with pH 4.0, 7.0 and 9.0 it being 0.153Â±0.012, 0.186Â±0.145 and 0.148Â±0.708, in respect of partition coefficient of that acid where it for water-benzene solvent as 0.636 and in buffer solutions is being 0.841, 0.624 and 0.589 respectively. In graphically, at different pH buffer solutions the solubility plot of acid in neutral pH (7.0) is higher than other acidic and basic, but it for distribution coefficient of acid in acidic (pH 4.0) medium is higher than both neutral and basic pH (9.0) medium.

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Bao, Quan-Ying, Ai-Yun Liu, Yu Ma, et al. "The effect of oil-water partition coefficient on the distribution and cellular uptake of liposome-encapsulated gold nanoparticles." Colloids and Surfaces B: Biointerfaces 146 (October 2016): 475–81. http://dx.doi.org/10.1016/j.colsurfb.2016.06.046.

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35

Tielker, Nicolas, Stefan Güssregen, and Stefan M. Kast. "SAMPL7 physical property prediction from EC-RISM theory." Journal of Computer-Aided Molecular Design 35, no. 8 (2021): 933–41. http://dx.doi.org/10.1007/s10822-021-00410-9.

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AbstractInspired by the successful application of the embedded cluster reference interaction site model (EC-RISM), a combination of quantum–mechanical calculations with three-dimensional RISM theory to predict Gibbs energies of species in solution within the SAMPL6.1 (acidity constants, pKa) and SAMPL6.2 (octanol–water partition coefficients, log P) the methodology was applied to the recent SAMPL7 physical property challenge on aqueous pKa and octanol–water log P values. Not part of the challenge but provided by the organizers, we also computed distribution coefficients log D7.4 from predicted pKa and log P data. While macroscopic pKa predictions compared very favorably with experimental data (root mean square error, RMSE 0.72 pK units), the performance of the log P model (RMSE 1.84) fell behind expectations from the SAMPL6.2 challenge, leading to reasonable log D7.4 predictions (RMSE 1.69) from combining the independent calculations. In the post-submission phase, conformations generated by different methodology yielded results that did not significantly improve the original predictions. While overall satisfactory compared to previous log D challenges, the predicted data suggest that further effort is needed for optimizing the robustness of the partition coefficient model within EC-RISM calculations and for shaping the agreement between experimental conditions and the corresponding model description.

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Ma, Yan, Xiao Ming Du, Yi Shi, et al. "Effect of Soil Water Content on the Removal of Volatile Chlorinated Hydrocarbons from Soil by Mechanical Soil Aeration." Applied Mechanics and Materials 737 (March 2015): 541–48. http://dx.doi.org/10.4028/www.scientific.net/amm.737.541.

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Mechanical soil aeration is an easy, effective, and low-cost soil remediation technology; in particular, it is suitable for large sites contaminated by volatile chlorinated hydrocarbons (VCHs). Mechanical soil aeration encourages the volatilization of soil contaminants, but soil moisture, which reduces the amount of open pores, may hinder this process. The present study examined the remediation of silty soil containing 1,2-dichloroethane (1,2-DCA), chloroform (TCM), trichloroethylene (TCE), and tetrachloroethylene (PCE) using mechanical soil aeration and evaluated the influence of soil water content on the efficiency of the process. For artificially contaminated soil, the following conclusions were reached: (i) moisture undermines the volatilization of contaminants. When the soil water content increased from 5% to 20%, the residual concentrations of 1,2-DCA, TCM, TCE, and PCE in the soil increased from 0.08, 0.10, 0.09, and 0.48 mg/kg to 1.43, 0.81, 1.16, and 1.43 mg/kg, respectively. The effective diffusion coefficients also decreased from 1.88×10-2, 1.43×10-2, 1.88×10-2, and 1.30×10-2 cm2/s to 1.71×10-6, 1.30×10-6, 1.71×10-6, and 1.18×10-6 cm2/s, respectively. (ii) Residual contaminants are related to the octanol-water partition coefficient. The soil-water distribution coefficient of PCE was highest among the hydrocarbons (3.72), and the residual contaminants were mainly adsorbed on soil particles. The soil-water distribution coefficient of DCA was lowest (0.42), and the residual contaminants were mainly dissolved in the soil water.

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Gecim, B., and W. O. Winer. "Transient Temperatures in the Vicinity of an Asperity Contact." Journal of Tribology 107, no. 3 (1985): 333–41. http://dx.doi.org/10.1115/1.3261068.

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The two dimensional, transient temperature distribution in the vicinity of a small, stationary, circular heat source is derived. The source is assumed to be acting on the surface of a relatively much larger body which can be treated as semi-infinite. Formulations both with and without surface convection are considered. Successive integral transforms are used to obtain a direct solution of the governing differential equation. The transient of local temperature rise is found to be very short and very localized in the immediate vicinity of the source. The auxiliary problem of pure convective cooling, i.e., no heat input, is also presented. The initial temperature distribution is taken to be the steady distribution already derived with the heat input. The transient of local temperature in cooling-off is found to be even shorter. In both the main and the auxiliary problems, the governing parameters are source radius, heat flux, thermal conductivity and thermal diffusivity. The convective coefficient does not have a significant effect. This study is intended to represent the thermal behavior of a single asperity in an apparent area of contact. The auxiliary problem represents the cooling-off of the asperity as it moves out from the apparent contact; or it may also be the cooling-off between two consecutive asperity collisions within an apparent contact. The analysis can also be applied to multiple sources acting simultaneously, provided that they are located sufficiently far away from each other, and thermal interaction is negligible. Because the heat generated at the asperity interface must be partitioned, a partition coefficient is derived in the appendix.

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Asuero, Agustin G. "Evaluation of partition coefficient and acidity constants of amphoteric substances by graphic differentiation of the distribution ratio against pH curve." International Journal of Pharmaceutics 45, no. 1-2 (1988): 157–59. http://dx.doi.org/10.1016/0378-5173(88)90045-2.

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Verner, Marc-André, Laurence Plouffe, Kyra K. Kieskamp, Inés Rodríguez-Leal, and Satori A. Marchitti. "Evaluating the influence of half-life, milk:plasma partition coefficient, and volume of distribution on lactational exposure to chemicals in children." Environment International 102 (May 2017): 223–29. http://dx.doi.org/10.1016/j.envint.2017.03.007.

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Xiong, Junnan, Chongchong Ye, Weiming Cheng, Liang Guo, Chenghu Zhou, and Xiaolei Zhang. "The Spatiotemporal Distribution of Flash Floods and Analysis of Partition Driving Forces in Yunnan Province." Sustainability 11, no. 10 (2019): 2926. http://dx.doi.org/10.3390/su11102926.

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Flash floods are one of the most serious natural disasters, and have a significant impact on economic development. In this study, we employed the spatiotemporal analysis method to measure the spatial–temporal distribution of flash floods and examined the relationship between flash floods and driving factors in different subregions of landcover. Furthermore, we analyzed the response of flash floods on the economic development by sensitivity analysis. The results indicated that the number of flash floods occurring annually increased gradually from 1949 to 2015, and regions with a high quantity of flash floods were concentrated in Zhaotong, Qujing, Kunming, Yuxi, Chuxiong, Dali, and Baoshan. Specifically, precipitation and elevation had a more significant effect on flash floods in the settlement than in other subregions, with a high r (Pearson’s correlation coefficient) value of 0.675, 0.674, 0.593, 0.519, and 0.395 for the 10 min precipitation in 20-year return period, elevation, 60 min precipitation in 20-year return period, 24 h precipitation in 20-year return period, and 6 h precipitation in 20-year return period, respectively. The sensitivity analysis showed that the Kunming had the highest sensitivity (S = 21.86) during 2000–2005. Based on the research results, we should focus on heavy precipitation events for flash flood prevention and forecasting in the short term; but human activities and ecosystem vulnerability should be controlled over the long term.

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Bartoszuk, Marian. "Temperature and Heat Partition Testing in the Cutting Zone for Turning AISI 321 Steel." Strojniški vestnik – Journal of Mechanical Engineering 66, no. 11 (2020): 629–41. http://dx.doi.org/10.5545/sv-jme.2020.6840.

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This article shows selected results of experimental tests and the results of analytical and numerical modelling of the thermal characteristics of the cutting process. The tests were conducted for the case of the dry turning of austenitic steel AISI 321 with cutting tools with a flat rake face. The research aimed to determine the actual division of thermal fluxes in the zone of contact between the chip and the rake face. As a result of such work, a formula for a new heat partition coefficient and a formula for calculating the average contact temperature were developed. The results showed that the formulas developed can be a useful tool to estimate heat distribution in the cutting zone quickly.

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Fischer, Ralf G., and K. Ballschmiter. "Prediction of the environmental distribution of alkyl dinitrates - Chromatographic determination of vapor pressure p 0 , water solubility S H 2 O , gas-water partition coefficient K GW (Henry's law constant) and octanol-water partition coefficient K OW." Fresenius' Journal of Analytical Chemistry 360, no. 7-8 (1998): 769–76. http://dx.doi.org/10.1007/s002160050803.

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Bast, Gabriele E. "Influence of solubility and permeant size on absorption and metabolism of xenobiotics in rabbit skin." Human & Experimental Toxicology 16, no. 8 (1997): 435–40. http://dx.doi.org/10.1177/096032719701600804.

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1 In order to obtain an understanding of the risks associated with dermal uptake of xenobiotics it is necessary to investigate the principles governing percutaneous absorption and metabolism. The sin gle-pass perfused rabbit ear served as a convenient model for the simultaneous study of absorption and metabolism of a variety of substances. We found: 2 When substances are applied in a lipophilic vehicle the permeation coefficient K P is notably decreased when the distribution coefficient (n-octanol/perfusion buffer (pH 7.4)) Poct. exceeds 2000. KP also decreases with increasing molecular weight. 3 Substances which are in the ionized state at pH 7.4 may have a higher permeation coefficient than would be expected from Poct. or by molecular weight. 4 The partition of a drug from the stratum corneum to the epidermal enzymes controls the extent of its metabo lism. However, substances with increased solubility at physiological pH are metabolized to a lesser extent than expected from their absorption rate.

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Paraíba, Lourival Costa, Vera Lúcia Scherholz Salgado de Castro, and Aline de Holanda Nunes Maia. "Insecticide distribution model in human tissues viewing worker's health monitoring programs." Brazilian Archives of Biology and Technology 52, no. 4 (2009): 875–81. http://dx.doi.org/10.1590/s1516-89132009000400011.

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This work aimed at evaluating the characteristics of thirty nine insecticides on tissue distribution and accumulation, using their physico-chemical characteristics and the tissues lipid contents to calculate the compounds distribution among the tissues. The insecticides evaluated were selected among those registered in Brazil for agriculture use. The level I fugacity model was used for the calculations of insecticide distribution among the tissues of muscles, viscera, skin, fat, blood, liver, kidneys and gut. The octanol-water partition coefficient, water solubility and tissue lipid contents showed an insecticide distribution in human tissues. Cluster analysis was performed aiming the identification and separation of insecticides groups based on their physico-chemical characteristics as compounds with similar distribution within tissues and at the same time tissues with similar distribution of various insecticides. Cluster analysis pointed out three insecticide groups: in the first, 70 - 86% of insecticide accumulation was found in lipid tissues; in the second, 44 - 58%; and in the third, 9 -19%. These results could contribute to health monitoring programs of farmworkers.

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Neurath, Susan K., Ali M. Sadeghi, Adel Shirmohammadi, Alba Torrents, and Kerry A. Sefton. "SENSITIVITY OF ATRAZINE PARTITION COEFFICIENT ON PESTICIDE ROOT ZONE MODEL PREDICTION OF SOIL'S ATRAZINE RESIDUE DISTRIBUTION WITHIN THE CROP ROOT ZONE." Soil Science 172, no. 1 (2007): 42–54. http://dx.doi.org/10.1097/01.ss.0000240546.59798.c3.

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Flacke, Sebastian J., Stefan E. Fischer, and Christine H. Lorenz. "Measurement of the Gadopentetate Dimeglumine Partition Coefficient in Human Myocardium in Vivo: Normal Distribution and Elevation in Acute and Chronic Infarction." Radiology 218, no. 3 (2001): 703–10. http://dx.doi.org/10.1148/radiology.218.3.r01fe18703.

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47

Sheppard, M. I., S. C. Sheppard, and C. A. Grant. "Solid/liquid partition coefficients to model trace element critical loads for agricultural soils in Canada." Canadian Journal of Soil Science 87, Special Issue (2007): 189–201. http://dx.doi.org/10.4141/s06-061.

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Canadian consumers are demanding a sustainable agricultural industry as well as products delivered under Best Management Practices (BMPs). Trace element accumulation in soils may influence crop productivity, food quality and ecosystem and human health. Canada’s feed and foodstuff export industry has already faced cases of penalties for high trace element content [cadmium (Cd) in durum wheat]. Thus, it is imperative to be able to estimate the accumulation and potential short- and long-term impacts of trace elements in soil. A national-level Trace Element Indicator (TEI) based on present loadings of trace elements to agricultural land is in progress. An Expert Panel including Canadian, American and Australian experts guided the assembly of a proposed methodology for this TEI. The proposed TEI, described briefly here, is a critical load approach with a single expression of the risk of impact from single or multiple trace elements from multiple sources (manures, biosolids, effluents and fertilizers and natural processes), invoked in a stochastic manner. Two key data requirements are the current background levels of trace elements in soil, and the leachability of these trace elements. A survey of total and soluble concentrations of 54 elements in up to 112 soils was completed. Although preliminary in scope, these represent key soil series in Canada. From this, a database of the solid/liquid partition coefficient, Kd, was computed. These Kd values will be used to characterize the leachability of the trace elements. Key words: Cadmium, copper, zinc, lead, nickel, uranium, metals, Kd, distribution coefficient

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Shen, Hai Long, Mo Du, and Yu Min Su. "Study of Microminiature Autonomous Underwater Vehicle Hull Form Based on CFD Technique." Advanced Materials Research 512-515 (May 2012): 2682–85. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.2682.

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Based on CFD technique，this paper discusses the applicability of different turbulence models and mesh partition method which are used to predict the hydrodynamic performance of AUV. Firstly, the hydrodynamic performance prediction method was gotten and was validated, and three different shapes autonomous underwater vehicles were designed. The hydrodynamic performances of the three autonomous underwater vehicles were predicted. Then, the advantage and disadvantage of the four autonomous underwater vehicles were obtained by comparing the resistance and pressure distribution. Based on these, two other AUV hulls were designed which combined the advantages of them, and the hydrodynamic performance was predicted. The calculation results showed that the resistance and hull pressure distribution were improved remarkably comparing with the parent model. The resistance coefficient of optimized hull is reduced by 20% compared to the parent hull.

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Robatto, F. M., S. Simard, and M. S. Ludwig. "How changes in the serial distribution of bronchoconstriction affect lung mechanics." Journal of Applied Physiology 74, no. 6 (1993): 2838–47. http://dx.doi.org/10.1152/jappl.1993.74.6.2838.

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It is generally accepted that methacholine (MCh) acts predominantly on the central airways and histamine (H) acts on the lung periphery. We hypothesized therefore that lung mechanics would be affected differently by H and MCh aerosols. In 12 anesthetized paralyzed open-chest mongrel dogs, we obtained MCh (0.1–30 mg/ml, n = 6) and H (0.1–30 mg/ml, n = 6) concentration-response curves. The alveolar capsule technique was used to partition lung resistance (RL) into airway (Raw) and tissue (Rti) components. The degree of mechanical heterogeneity across the lung was assessed by computing the coefficient of variation for five alveolar pressures during relaxed expirations. RL increased 823 +/- 202% after H and 992 +/- 219% after MCh. Rti increased 784 +/- 192% after H and 1,014 +/- 279% after MCh. Raw increased 1,098 +/- 297% after H and 1,275 +/- 332% after MCh. Elastance increased 342 +/- 53% after H and 423 +/- 88% after MCh. The coefficient of variation increased 279 +/- 65% after H and 252 +/- 55% after MCh. The patterns of change were similar throughout the H and MCh concentration-response curves. We conclude that H and MCh have comparable effects on lung mechanics and that the degree and pattern of heterogeneity inside the lung after constriction are the same regardless of the agent used. These data support the hypothesis that H and MCh have some similar direct effect on the lung parenchyma. Parenchymal deformation after MCh-induced central airway constriction alone would be unlikely to explain increases in Rti of this magnitude or changes in lung mechanics so similar to those induced by H.

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Zhang, Xiaobing, Fitz-Roy Curry, and Sheldon Weinbaum. "Mechanism of osmotic flow in a periodic fiber array." American Journal of Physiology-Heart and Circulatory Physiology 290, no. 2 (2006): H844—H852. http://dx.doi.org/10.1152/ajpheart.00695.2005.

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The classic analysis by Anderson and Malone ( Biophys J 14: 957–982, 1974) of the osmotic flow across membranes with long circular cylindrical pores is extended to a fiber matrix layer wherein the confining boundaries are the fibers themselves. The equivalent of the well-known result for the reflection coefficient σ0 = (1 − φ)2, where φ is the partition coefficient, is derived for a periodic fiber array of hexagonally ordered core proteins. The boundary value problem for the potential energy function describing the solute distribution surrounding each fiber is solved by defining an equivalent fluid annulus in which the pressures and osmotic forces are determined. This model is of special interest in the osmotic flow of water across a capillary wall, where recent experimental studies suggest that the endothelial glycocalyx is a quasiperiodic fiber array that serves as the primary molecular sieve for plasma proteins. Results for the reflection coefficient are presented in terms of two dimensionless numbers, α = a/ R and β = b/ R, where a and b are the solute and fiber radii, respectively, and R is the outer radius of the fluid annulus. In general, the results differ substantially from the classic expression for a circular pore because of the large difference in the shape of the boundary along which the osmotic force is generated. However, as in circular pore theory, one finds that the reflection coefficients for osmosis and filtration are the same.

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Journal articles on the topic 'Distribution/partition coefficient'

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