Sample records for solubilities partition coefficients

  1. Buckminsterfullerene's (C60) octanol-water partition coefficient (Kow) and aqueous solubility.

    Jafvert, Chad T; Kulkarni, Pradnya P


    To assess the risk and fate of fullerene C60 in the environment, its water solubility and partition coefficients in various systems are useful. In this study, the log Kow of C60 was measured to be 6.67, and the toluene-water partition coefficient was measured at log Ktw = 8.44. From these values and the respective solubilities of C60 in water-saturated octanol and water-saturated toluene, C60's aqueous solubility was calculated at 7.96 ng/L(1.11 x 10(-11) M) for the organic solvent-saturated aqueous phase. Additionally, the solubility of C60 was measured in mixtures of ethanol-water and tetrahydrofuran-water and modeled with Wohl's equation to confirm the accuracy of the calculated solubility value. Results of a generator column experiment strongly support the hypothesis that clusters form at aqueous concentrations below or near this calculated solubility. The Kow value is compared to those of other hydrophobic organic compounds, and bioconcentration factors for C60 were estimated on the basis of Kow.

  2. A new approach on estimation of solubility and n-octanol/water partition coefficient for organohalogen compounds.

    Gao, Shuo; Cao, Chenzhong


    The aqueous solubility (logW) and n-octanol/water partition coefficient (logP(OW)) are important properties for pharmacology, toxicology and medicinal chemistry. Based on an understanding of the dissolution process, the frontier orbital interaction model was suggested in the present paper to describe the solvent-solute interactions of organohalogen compounds and a general three-parameter model was proposed to predict the aqueous solubility and n-octanol/water partition coefficient for the organohalogen compounds containing nonhydrogen-binding interactions. The model has satisfactory prediction accuracy. Furthermore, every item in the model has a very explicit meaning, which should be helpful to understand the structure-solubility relationship and may be provide a new view on estimation of solubility.

  3. A New Approach on Estimation of Solubility and n-Octanol/ Water Partition Coefficient for Organohalogen Compounds

    Chenzhong Cao


    Full Text Available The aqueous solubility (logW and n-octanol/water partition coefficient (logPOW are important properties for pharmacology, toxicology and medicinal chemistry. Based on an understanding of the dissolution process, the frontier orbital interaction model was suggested in the present paper to describe the solvent-solute interactions of organohalogen compounds and a general three-parameter model was proposed to predict the aqueous solubility and n-octanol/water partition coefficient for the organohalogen compounds containing nonhydrogen-binding interactions. The model has satisfactory prediction accuracy. Furthermore, every item in the model has a very explicit meaning, which should be helpful to understand the structure-solubility relationship and may be provide a new view on estimation of solubility.

  4. Estimation of octanol/water partition coefficient and aqueous solubility of environmental chemicals using molecular fingerprints and machine learning methods

    Octanol/water partition coefficient (logP) and aqueous solubility (logS) are two important parameters in pharmacology and toxicology studies, and experimental measurements are usually time-consuming and expensive. In the present research, novel methods are presented for the estim...

  5. Estimation of octanol/water partition coefficient and aqueous solubility of environmental chemicals using molecular fingerprints and machine learning methods

    Octanol/water partition coefficient (logP) and aqueous solubility (logS) are two important parameters in pharmacology and toxicology studies, and experimental measurements are usually time-consuming and expensive. In the present research, novel methods are presented for the estim...

  6. Aqueous solubilities, vapor pressures, and 1-octanol-water partition coefficients for C9-C14 linear alkylbenzenes

    Sherblom, P.M.; Gschwend, P.M.; Eganhouse, R.P.


    Measurements and estimates of aqueous solubilities, 1-octanol-water partition coefficients (Kow), and vapor pressures were made for 29 linear alkylbenzenes having alkyl chain lengths of 9-14 carbons. The ranges of values observed were vapor pressures from 0.002 to 0.418 Pa, log Kow, from 6.83 to 9.95, and aqueous solubilities from 4 to 38 nmol??L-1. Measured values exhibited a relationship to both the alkyl chain length and the position of phenyl substitution on the alkyl chain. Measurement of the aqueous concentrations resulting from equilibration of a mixture of alkylbenzenes yielded higher than expected values, indicating cosolute or other interactive effects caused enhanced aqueous concentrations of these compounds. ?? 1992 American Chemical Society.

  7. Improved prediction of octanol-water partition coefficients from liquid-solute water solubilities and molar volumes

    Chiou, C.T.; Schmedding, D.W.; Manes, M.


    A volume-fraction-based solvent-water partition model for dilute solutes, in which the partition coefficient shows a dependence on solute molar volume (V??), is adapted to predict the octanol-water partition coefficient (K ow) from the liquid or supercooled-liquid solute water solubility (Sw), or vice versa. The established correlation is tested for a wide range of industrial compounds and pesticides (e.g., halogenated aliphatic hydrocarbons, alkylbenzenes, halogenated benzenes, ethers, esters, PAHs, PCBs, organochlorines, organophosphates, carbamates, and amidesureas-triazines), which comprise a total of 215 test compounds spanning about 10 orders of magnitude in Sw and 8.5 orders of magnitude in Kow. Except for phenols and alcohols, which require special considerations of the Kow data, the correlation predicts the Kow within 0.1 log units for most compounds, much independent of the compound type or the magnitude in K ow. With reliable Sw and V data for compounds of interest, the correlation provides an effective means for either predicting the unavailable log Kow values or verifying the reliability of the reported log Kow data. ?? 2005 American Chemical Society.

  8. Application of TLSER method in predicting the aqueous solubility and n-octanol/water partition coefficient of PCBs, PCDDs and PCDFs

    HUANG Jun; YU Gang; ZHANG Zu-lin; WANG Yi-lei; ZHU Wei-hua; WU Guo-shi


    The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and noctanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls( PCBs), polychlorinated dibenzodioxins and dibenzofurans( PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AMI semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(α), energy of the lowest unoccupied molecular orbit( ELUMO ), energy of the highest occupied molecular orbit( EHOMO ), the most positive charge on a hydrogen atom ( q + ), and the most negative atomic partial charge( q_ ) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n-octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models.The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties ofmacromolecular chemicals, such as persistent organic pollutants.

  9. Estimating the physicochemical properties of polyhalogenated aromatic and aliphatic compounds using UPPER: part 2. Aqueous solubility, octanol solubility and octanol-water partition coefficient.

    Admire, Brittany; Lian, Bo; Yalkowsky, Samuel H


    The UPPER (Unified Physicochemical Property Estimation Relationships) model uses additive and non-additive parameters to estimate 20 biologically relevant properties of organic compounds. The model has been validated by Lian and Yalkowsky (2014) on a data set of 700 hydrocarbons. Recently, Admire et al. (2014) expanded the model to predict the boiling and melting points of 1288 polyhalogenated benzenes, biphenyls, dibenzo-p-dioxins, diphenyl ethers, anisoles and alkanes. In this work, 19 new group descriptors are determined and used to predict the aqueous solubilities, octanol solubilities and the octanol-water coefficients.

  10. Review of methods and measurements of selected hydrophobic organic contaminant aqueous solubilities, vapor pressures, and air-water partition coefficients

    Bamford, H.A.; Baker, J.E.; Poster, D.L.


    Aqueous solubilities, vapor pressures, and Henry`s law constants for a wide range of organic contaminants of environmental interest are presented. Specifically, a discussion of methods used to measure these physical constants and resulting measurements are provided in an effort to examine the scope of physical constants reported in the scientific literature. Physical constants reviewed include those for 40 PAHs, 14 chlorinated aliphatics, 149 PCBs, 12 chlorinated benzenes, 16 dioxins, 63 furans, and 29 agrochemicals (a total of 323 compounds) and overall a total of 1,605 values are listed.

  11. The search for reliable aqueous solubility (Sw) and octanol-water partition coefficient (Kow) data for hydrophobic organic compounds; DDT and DDE as a case study

    Pontolillo, James; Eganhouse, R.P.


    The accurate determination of an organic contaminant?s physico-chemical properties is essential for predicting its environmental impact and fate. Approximately 700 publications (1944?2001) were reviewed and all known aqueous solubilities (Sw) and octanol-water partition coefficients (Kow) for the organochlorine pesticide, DDT, and its persistent metabolite, DDE were compiled and examined. Two problems are evident with the available database: 1) egregious errors in reporting data and references, and 2) poor data quality and/or inadequate documentation of procedures. The published literature (particularly the collative literature such as compilation articles and handbooks) is characterized by a preponderance of unnecessary data duplication. Numerous data and citation errors are also present in the literature. The percentage of original Sw and Kow data in compilations has decreased with time, and in the most recent publications (1994?97) it composes only 6?26 percent of the reported data. The variability of original DDT/DDE Sw and Kow data spans 2?4 orders of magnitude, and there is little indication that the uncertainty in these properties has declined over the last 5 decades. A criteria-based evaluation of DDT/DDE Sw and Kow data sources shows that 95?100 percent of the database literature is of poor or unevaluatable quality. The accuracy and reliability of the vast majority of the data are unknown due to inadequate documentation of the methods of determination used by the authors. [For example, estimates of precision have been reported for only 20 percent of experimental Sw data and 10 percent of experimental Kow data.] Computational methods for estimating these parameters have been increasingly substituted for direct or indirect experimental determination despite the fact that the data used for model development and validation may be of unknown reliability. Because of the prevalence of errors, the lack of methodological documentation, and unsatisfactory data

  12. In-vitro permeability of the human nail and of a keratin membrane from bovine hooves: influence of the partition coefficient octanol/water and the water solubility of drugs on their permeability and maximum flux.

    Mertin, D; Lippold, B C


    Penetration of homologous nicotinic acid esters through the human nail and a keratin membrane from bovine hooves was investigated by modified Franz diffusion cells in-vitro to study the transport mechanism. The partition coefficient octanol/water PCOct/W of the esters was over the range 7 to > 51,000. The permeability coefficient P of the nail plate as well as the hoof membrane did not increase with increasing partition coefficient or lipophilicity of the penetrating substance. This indicates that both barriers behave like hydrophilic gel membranes rather than lipophilic partition membranes as in the case of the stratum corneum. Penetration studies with the model compounds paracetamol and phenacetin showed that the maximum flux was first a function of the drug solubility in water or in the swollen keratin matrix. Dissociation hindered the diffusion of benzoic acid and pyridine through the hoof membrane. Since keratin, a protein with an isoelectric point of about 5, is also charged, this reduction can be attributed to an exclusion of the dissociating substance due to the Donnan equilibrium. Nevertheless, the simultaneous enhancement of the water solubility makes a distinct increase of the maximum flux possible. In order to screen drugs for potential topical application to the nail plate, attention has to be paid mainly to the water solubility of the compound. The bovine hoof membrane may serve as an appropriate model for the nail.

  13. 胡椒碱平衡溶解度和表观油水分配系数的测定%Determination of equilibrium solubility and apparent oil/water partition coefficient of piperine

    吴珍菊; 夏学进; 黄雪松


    This study aimed to investigate the equilibrium solubility of piperine and its partition coefficient in the n-octanol-water/buffer solution systems, which could provide scientific information for the studies of its in vivo absorption. The concentrations of piperine in water and five organic solvents were determined by HPLC analysis,and the partition coefficients were calculated by the peak area. The results showed that the equilibrium solubility of piperine was 22. 34 mg/L in water at 25 t. A higher equilibrum solubility was observed at 43 665. 5 mg/L in dichloromethane, while the partition coefficient of piperine in the n-octanol-water: buffer solution systems was found at 179. 33(lgP=2. 25).%测定胡椒碱的平衡溶解度及表观油水分配系数,研究pH值对其影响,为胡椒碱在体内吸收研究提供参考.采用HPLC法测定了胡椒碱在水和5种有机溶剂中的平衡溶解质量浓度,并用摇瓶法测定胡椒碱在不同pH条件下的正辛醇-水缓冲溶液中的表观油水分配系数.结果表明:25℃下胡椒碱在水中的平衡溶解质量浓度为22.34 mg/L,而在有机溶剂中的溶解质量浓度较好,特别是在二氯甲烷中,其平衡溶解质量浓度高达43 665.5 mg/L,正辛醇:水的表观油水分配系数P为179.33(lgP=2.25).

  14. Determination of Equilibrium Solubility and Apparent Oil/Water Partition Coefficient of Daphnetin%瑞香素平衡溶解度和表观油水分配系数的测定

    单进军; 狄留庆; 赵晓莉; 徐建亚


    OBJECTIVE To determine the equilibrium solubility of daphnetin and its partition coefficients for the n-oc-tanol-water/buffer solution systems. METHODS A high HPLC was established to detect the concentration of daphnetin in water and seven organic solvents. The partition coefficients for the n-octanol-water/buffer solution systems of daphnetin were determined by shaking flask method. RESULTS The equilibrium solubility of daphnetin was 176. 7 μg/mL in water at 25℃, a higher equilibrium solubility of daphnetin was reached at 485. 4 μg/mL in methanol, Papp of daphnetin was 2.4 (lgPapp =0.38).CONCLUSION The solubility of daphnetin was poor. It had little change in apparent partition coefficient in acidic and neutral phosphate buffer solution. Daphnetin belongs to the class II drug of Biopharmaceutics Classification System(low solubility, high permeability).%目的 测定瑞香素的平衡溶解度及表现油水分配系数.方法 采用HPLC法测定了瑞香素在水和7种有机溶剂中的平衡溶解度,摇瓶法测定瑞香素在正辛醇-水/缓冲盐溶液中的表现油水分配系数.结果 25℃下瑞香素在水中的平衡溶解度为176.7μg/mL,常用有机溶剂甲醇对瑞香素的溶解性较好,为485.4μg/mL,正辛醇/水表现分配系数Papp为2.4(lgPapp=0.38).结论 瑞香素的水溶性差,在酸性和中性条件下,正辛醇/缓冲液分配系数受缓冲液的pH值影响不大;瑞香素属于FDA生物药剂学分类中的第二类药物(低溶解性、高渗透性).

  15. Determination of equilibrium solubility and apparent oil/water partition coefficient of silymarin%水飞蓟素平衡溶解度及表观油水分配系数的测定

    何琳; 龙晓英; 丁沐淦; 叶晓芬; 梁静敏; 顾嘉慧; 李志棠; 李国辉


    Objective To determine the equilibrium solubility and the apparent oil/water partition coefficient of silymarin in different pH phosphate buffer solutions in 37 ℃. Methods A shake flask-ultraviolet spectrophotometry method was applied to determine the equilibrium solubility and partition coefficient of silymarin. Concentrations of silymarin in n-octanol-buffer solutions of different pH were detected by UV. Results The equilibrium solubility of silymarin in different phosphate buffer solution of pH 2.0,3.0,4.0,5.0, 6.0,6.8,7.4,8.0,9.0 were 0.673,0. 681,0.776,0.848,0.937,1.218,1.486,1.504,1.691 mg · mL-1, and the oil/water apparent partition coefficient of silymarin in different pH respectively were 57. 12,10. 83, 15. 56,7.39,10.19,3.82,2.75,1.79,0. 84 in 37℃. Conclusion The equilibrium solubility and apparent oil/ water partition coefficient were correlated to the pH of medium. With the increase of pH value, the equilibrium solubility rised, while the apparent oil/water partition coefficient decreased.%目的 考察水飞蓟素在37℃下,在不同pH磷酸盐缓冲溶液中的平衡溶解度和表观油水分配系数.方法 采用气浴恒温振荡器摇瓶法测定水飞蓟素的平衡溶解度及表观油水分配系数,紫外-可见分光光度法测定水飞蓟素在正辛醇-缓冲体系的质量浓度.结果 37℃时,水飞蓟素在pH 2.0、3.0、4.0、5.0、6.0、6.8、7.4、8.0、9.0的磷酸盐缓冲液中的平衡溶解度分别为0.673、0.681、0.776、0.848、0.937、1.218、1.486、1.504、1.691 mg· mL-1,相应条件下的表观油水分配系数分别为57.12、10.83、15.56、7.39、10.19、3.82、2.75、1.79、0.84.结论 水飞蓟素在磷酸盐缓冲溶液中的平衡溶解度及表观油水分配系数与介质的pH值相关,介质的pH值增大,水飞蓟素平衡溶解度增大,表观油水分配系数减小.

  16. Partitioning coefficients between olivine and silicate melts

    Bédard, J. H.


    Variation of Nernst partition coefficients ( D) between olivine and silicate melts cannot be neglected when modeling partial melting and fractional crystallization. Published natural and experimental olivine/liquidD data were examined for covariation with pressure, temperature, olivine forsterite content, and melt SiO 2, H 2O, MgO and MgO/MgO + FeO total. Values of olivine/liquidD generally increase with decreasing temperature and melt MgO content, and with increasing melt SiO 2 content, but generally show poor correlations with other variables. Multi-element olivine/liquidD profiles calculated from regressions of D REE-Sc-Y vs. melt MgO content are compared to results of the Lattice Strain Model to link melt MgO and: D0 (the strain compensated partition coefficient), EM3+ (Young's Modulus), and r0 (the size of the M site). Ln D0 varies linearly with Ln MgO in the melt; EM3+ varies linearly with melt MgO, with a dog-leg at ca. 1.5% MgO; and r0 remains constant at 0.807 Å. These equations are then used to calculate olivine/liquidD for these elements using the Lattice Strain Model. These empirical parameterizations of olivine/liquidD variations yield results comparable to experimental or natural partitioning data, and can easily be integrated into existing trace element modeling algorithms. The olivine/liquidD data suggest that basaltic melts in equilibrium with pure olivine may acquire small negative Ta-Hf-Zr-Ti anomalies, but that negative Nb anomalies are unlikely to develop. Misfits between results of the Lattice Strain Model and most light rare earth and large ion lithophile partitioning data suggest that kinetic effects may limit the lower value of D for extremely incompatible elements in natural situations characterized by high cooling/crystallization rates.

  17. Determination of the Solubility and Apparent Oil-water Partition Coefficient of Curcumin and Piperine%姜黄素和胡椒碱溶解度和表观油水分配系数的测定

    涂瑶生; 付建武; 张建军; 崔景朝; 曾晓会


    目的:测定姜黄素和胡椒碱的溶解度及表观油水分配系数,研究pH值对其的影响,为姜黄素和胡椒碱的剂型设计提供参考。方法:采用HPLC法在同一条件下测定姜黄素和胡椒碱的含量,并测定姜黄素和胡椒碱在不同有机溶剂中的溶解性,采用摇瓶法测定姜黄素和胡椒碱在不同pH条件下的表观溶解度,并对其在正辛醇-水缓冲溶液中的表观油水分配系数进行测定。结果:姜黄素在无水乙醇、丙二醇、丙三醇、PEG400和正辛醇中的溶解度分别为0.0214g·ml-1、0.0201g·ml-1、0.0100g· ml-1、0.0636g·ml-1和0.0328g·ml-1,胡椒碱在无水乙醇、丙二醇、丙三醇、PEG400和正辛醇中的溶解度分别为0.0478g·ml-1、0.0220g·ml-1、0.0128g·ml-1、0.0619g·ml-1和0.0443g·ml-1;25℃下姜黄素和胡椒碱的表观正辛醇/水分配系数P分别为4738.609(Log P=3.6757)和72.9199(Log P=1.8628)。结论:姜黄素在不同的pH缓冲溶液中不溶,而胡椒碱在不同的缓冲溶液中均具有一定的溶解性,随着pH的升高溶解度逐步增加;姜黄素和胡椒碱均为脂溶性成分,较难溶于水。%Objective:To determine the solubility, apparent oil-water partition coefficient and the pH value of its implications of curcumin and piper-ine, which can provide reference for novel exploitation. Methods:The concentrations of curcumin and piperine and the solubility of them in different organic solvents were determined by HPLC at the same conditions. The determination of curcumin and piperine at different pH conditions apparent solubility, and its apparent oil-water partition coefficient was measured by shake flask. Results:Solubility of Curcumin in ethanol, propylene glycol , glycerol , PEG400 and n-octanol were 0.021 4 g·ml-1, 0.020 1 g·ml-1, 0.010 0 g·ml-1, 0.063 6 g·ml-1 and 0.032 8 g·ml-1, furthermore, the solubil-ity of piperine in ethanol, propylene glycol , glycerol , PEG400 solubility

  18. Polymer-water partition coefficients in polymeric passive samplers.

    Asgarpour Khansary, Milad; Shirazian, Saeed; Asadollahzadeh, Mehdi


    Passive samplers are of the most applied methods and tools for measuring concentration of hydrophobic organic compounds in water (c 1(W) ) in which the polymer-water partition coefficients (D) are of fundamental importance for reliability of measurements. Due to the cost and time associated with the experimental researches, development of a predictive method for estimation and evaluation of performance of polymeric passive samplers for various hydrophobic organic compounds is highly needed and valuable. For this purpose, in this work, following the fundamental chemical thermodynamic equations governing the concerned local equilibrium, successful attempts were made to establish a theoretical model of polymer-water partition coefficients. Flory-Huggins model based on the Hansen solubility parameters was used for calculation of activity coefficients. The method was examined for reliability of calculations using collected data of three polymeric passive samplers and ten compounds. A regression model of form ln(D) = 0.707ln(c 1(p) ) - 2.7391 with an R (2)  = 0.9744 was obtained to relate the polymer-water partition coefficients (D) and concentration of hydrophobic organic compounds in passive sampler (c 1(p) ). It was also found that polymer-water partition coefficients are related to the concentration of hydrophobic organic compounds in water (c 1(W) ) as ln(D) = 2.412ln(c 1(p) ) - 9.348. Based on the results, the tie lines of concentration for hydrophobic organic compounds in passive sampler (c 1(p) ) and concentration of hydrophobic organic compounds in water (c 1(W) ) are in the form of ln(c 1(W) ) = 0.293ln(c 1(p) ) + 2.734. The composition of water sample and the interaction parameters of dissolved compound-water and dissolved compound-polymer, temperature, etc. actively influence the values of partition coefficient. The discrepancy observed over experimental data can be simply justified based on the local condition of sampling sites which alter

  19. 苯系物溶解度和分配系数的测定与估算%Measurement and Estimation of Water Solubility and Octanol-Water Partition Coefficient for Benzene Substances

    陈慧; 杨瑞强; 张彰; 周文军; 姜梅


    Shake-flask gas-chromatography (GC) method was utilized tomeasure water solubility (Sw) and n-octanol water partition coefficient (Kow) for benzene, toluene and ethylbenzene respectively. The results showed that Sw and Kow followed a linear relationship as lnKow=0.455 8-0.917 6lnSw. Additionally, the experimental values well agreed to that calculated by structure information estimation method (Irmann method) and molar volume method (Mv method).%采用气相色谱的分析技术,用摇瓶法分别测定了苯,甲苯,乙苯的溶解度(Sw)和分配系数(Kow).结果表明,溶解度和分配系数之间存在线性关系:lnKow=0.4558-0.9176lnSw.并且运用结构法和摩尔体积法估算了苯及其简单同系物的溶解度和分配系数.估算结果与实验结果能较好吻合,说明估算法是一种简便、可靠的方法.

  20. Predicting blood:air partition coefficients using basic physicochemical properties

    Buist, H.E.; Wit-Bos, L. de; Bouwman, T.; Vaes, W.H.J.


    Quantitative Property Property Relationships (QPPRs) for human and rat blood:air partition coefficients (PBAs) have been derived, based on vapour pressure (Log(VP)), the octanol:water partition coefficient (Log(K_OW)) and molecular weight (MW), using partial least squares multilinear modelling. Thes

  1. REE and Strontium Partition Coefficients for Nakhla Pyroxenes

    Oe, K.; McKay, G.; Le, L.


    We present new partition coefficients for REE and Sr determined using a synthetic melt that crystallizes pyroxenes very similar in composition to Nakhla pyroxene cores. We believe these are the most appropriate partition coefficients to use in studying Nakhla Additional information is contained in the original extended abstract..

  2. Fractional crystallization of iron meteorites: Constant versus changing partition coefficients

    Jones, J. H.


    Analyses of magmatic iron meteorites, plotted on LogC(sub i) vs LogC(sub Ni) diagrams, often form linear arrays. Traditionally, this linearity has been ascribed to fractional crystallization under the assumption of constant partition coefficients (i.e., Rayleigh fractionation). Paradoxically, however, partition coefficients in the Fe-Ni-S-P system are decidedly not constant. This contribution provides a rationale for understanding how trends on LogC(sub i) vs LogC(sub Ni) diagrams can be linear, even when partition coefficients are changing rapidly.

  3. Mapping Pesticide Partition Coefficients By Electromagnetic Induction

    A potential method for reducing pesticide leaching is to base application rates on the leaching potential of a specific chemical and soil combination. However, leaching is determined in part by the partitioning of the chemical between the soil and soil solution, which varies across a field. Standard...


    Mbah J Chika


    Full Text Available The objective of the present study was to investigate the effect of pH control on the aqueous solubility and partition coefficient of trandolapril respectively. The aqueous solubility was determined at 25 ° C using pH values of 1.0,2.0,4.0,5.0,5.4,5.8, 6.4, 8.0 and 9.0 respectively. The aqueous solubility of the drug was also studied at 35 ° C and 45 ° C respectively. The partition coefficient of trandolapril was determined at 25 ° C between chloroform and aqueous buffer solutions using pH values of 2.0, 4.4, 5.0, 5.4, 5.8, 6.4, 7.4 and 9.0 respectively. The pH-solubility profile of trandolapril showed an intrinsic solubility of 3.524  10-2 mg/ml at 25 1° C. The pH-dependency of the apparent chloroform-water partition coefficient of trandolapril gave a partition coefficient of 58.88 for free trandolapril. The results of the study allowed the dissociation constant of the drug to be calculated. The physicochemical data obtained at alkaline pH ( 9.0 can be useful in the development of pharmaceutical liquid dosage forms of the drug.

  5. Determination of Solubility and Oil-water Partition Coefficient of Artemisinin by HPLC-ECD%HPLC-ECD法测定青蒿素溶解度及油水分配系数

    王振华; 梁家龙; 曾令清; 田军; 马国辉


    目的:建立一种便捷灵敏的青蒿素含量测定方法,并测定其在不同溶剂中的溶解度及油水分配系数。方法均匀试验设计优化青蒿素的柱前衍生条件,采用HPLC-ECD法进行测定。结果优化的青蒿素柱前衍生条件为:1 mL青蒿素无水乙醇溶液与4 mL氢氧化钠0.01 mol·L-1于70℃水浴中反应50 min后,冷却至室温,再加入5 mL醋酸0.06 mol·L-1。青蒿素在0.0015~0.7500μg范围内线性关系良好。结论建立的柱前衍生HPLC-ECD法专属性强、灵敏度高,适用于青蒿素的测定。%Objective To establish a sensitive assay method for artemisinin, and to detect the solubility as well as its oil-water partition coefficient in different solvents. Methods The pre-column derivatization of artemisinin was optimized by uniform design, and the determination of artemisinin was performed by HPLC-ECD. Results The optimal pre-column derivatization conditions were as follows: one milliliter of artemisinin anhydrous ethanol solution and 4 mL 0.01 mol·L-1 sodium hydroxide were reacted in 70℃water bath for 50 min , and then cooled to room temperature with 5 mL of 0.06 mol ·L-1 acetic acid added. The content of artemisinin showed good linearity in the range of 0.0015~0.7500 μg. Conclusion The pre-column derivatization HPLC-ECD method is highly specific and sensitive , and can be used for the assay of artemisinin.

  6. Why the partition coefficient of ionic liquids is concentration-dependent.

    Köddermann, Thorsten; Reith, Dirk; Arnold, A


    The partition coefficient of a substance measures its solubility in octanol compared with water and is widely used to estimate toxicity. If a substance is hardly soluble in octanol, then it is practically impossible for it to enter (human) cells and therefore is less likely to be toxic. For novel drugs it might be important to penetrate the cell through the membrane or even integrate into it. While for most simple substances the partition coefficient is concentration-independent at low concentrations, this is not true for a few important classes of complex molecules, such as ionic liquids or tensides. We present a simple association-dissociation model for concentration dependence of the partition coefficient of ionic liquids. Atomistic computer simulations serve to parametrize our model by calculating solvation free energies in water and octanol using thermodynamic integration. We demonstrate the validity of the method by reproducing the concentration-independent partition coefficients of small alcohols and the concentration-dependent partition coefficient of a commonly used ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4MIM][NTf2]. The concentration dependence is accurately predicted in a concentration range of several orders of magnitude.

  7. Orientation and velocity dependence of the nonequilibrium partition coefficient

    Beatty, K. M.; Jackson, K. A.


    Monte Carlo simulations based on a Spin-1 Ising Model for binary alloys have been used to investigate the non-equilibrium partition coefficient (k(sub neq)) as a function of solid-liquid interface velocity and orientation. In simulations of Si with a second component k(sub neq) is greater in the [111] direction than the [100] direction in agreement with experimental results reported by Azlz et al. The simulated partition coefficient scales with the square of the step velocity divided by the diffusion coefficient of the secondary component in the liquid.

  8. The influence of hydrogen bonding on partition coefficients

    Borges, Nádia Melo; Kenny, Peter W.; Montanari, Carlos A.; Prokopczyk, Igor M.; Ribeiro, Jean F. R.; Rocha, Josmar R.; Sartori, Geraldo Rodrigues


    This Perspective explores how consideration of hydrogen bonding can be used to both predict and better understand partition coefficients. It is shown how polarity of both compounds and substructures can be estimated from measured alkane/water partition coefficients. When polarity is defined in this manner, hydrogen bond donors are typically less polar than hydrogen bond acceptors. Analysis of alkane/water partition coefficients in conjunction with molecular electrostatic potential calculations suggests that aromatic chloro substituents may be less lipophilic than is generally believed and that some of the effect of chloro-substitution stems from making the aromatic π-cloud less available to hydrogen bond donors. Relationships between polarity and calculated hydrogen bond basicity are derived for aromatic nitrogen and carbonyl oxygen. Aligned hydrogen bond acceptors appear to present special challenges for prediction of alkane/water partition coefficients and this may reflect `frustration' of solvation resulting from overlapping hydration spheres. It is also shown how calculated hydrogen bond basicity can be used to model the effect of aromatic aza-substitution on octanol/water partition coefficients.

  9. The influence of hydrogen bonding on partition coefficients

    Borges, Nádia Melo; Kenny, Peter W.; Montanari, Carlos A.; Prokopczyk, Igor M.; Ribeiro, Jean F. R.; Rocha, Josmar R.; Sartori, Geraldo Rodrigues


    This Perspective explores how consideration of hydrogen bonding can be used to both predict and better understand partition coefficients. It is shown how polarity of both compounds and substructures can be estimated from measured alkane/water partition coefficients. When polarity is defined in this manner, hydrogen bond donors are typically less polar than hydrogen bond acceptors. Analysis of alkane/water partition coefficients in conjunction with molecular electrostatic potential calculations suggests that aromatic chloro substituents may be less lipophilic than is generally believed and that some of the effect of chloro-substitution stems from making the aromatic π-cloud less available to hydrogen bond donors. Relationships between polarity and calculated hydrogen bond basicity are derived for aromatic nitrogen and carbonyl oxygen. Aligned hydrogen bond acceptors appear to present special challenges for prediction of alkane/water partition coefficients and this may reflect `frustration' of solvation resulting from overlapping hydration spheres. It is also shown how calculated hydrogen bond basicity can be used to model the effect of aromatic aza-substitution on octanol/water partition coefficients.

  10. Estimation of octanol/water partition coefficients using LSER parameters

    Luehrs, Dean C.; Hickey, James P.; Godbole, Kalpana A.; Rogers, Tony N.


    The logarithms of octanol/water partition coefficients, logKow, were regressed against the linear solvation energy relationship (LSER) parameters for a training set of 981 diverse organic chemicals. The standard deviation for logKow was 0.49. The regression equation was then used to estimate logKow for a test of 146 chemicals which included pesticides and other diverse polyfunctional compounds. Thus the octanol/water partition coefficient may be estimated by LSER parameters without elaborate software but only moderate accuracy should be expected.

  11. Estimation of high temperature metal-silicate partition coefficients

    Jones, John H.; Capobianco, Christopher J.; Drake, Michael J.


    It has been known for some time that abundances of siderophile elements in the upper mantle of the Earth are far in excess of those expected from equilibrium between metal and silicate at low pressures and temperatures. Murthy (1991) has re-examined this excess of siderophile element problem by estimating liquid metal/liquid silicate partition coefficients reduces from their measured values at a lower temperature, implying that siderophile elements become much less siderophilic at high temperatures. Murthy then draws the important conclusion that metal/silicate equilibrium at high temperatures can account for the abundances of siderophile elements in the Earth's mantle. Of course, his conclusion is critically dependent on the small values of the partition coefficients he calculates. Because the numerical values of most experimentally-determined partition coefficients increase with increasing temperature at both constant oxygen fugacity and at constant redox buffer, we think it is important to try an alternative extrapolation for comparison. We have computed high temperature metal/silicate partition coefficients under a different set of assumptions and show that such long temperature extrapolations yield values which are critically dependent upon the presumed chemical behavior of the siderophile elements in the system.

  12. n-Alcohol/Water Partition Coefficients for Decachlorobiphenyl (PCB 209)

    Measurements of n-octanol/water partition coefficients (Kow) for highly hydrophobic chemicals are extremely difficult and are rarely made, in part due to the large volumes of water typically needed to quantify these compounds in the aqueous phase. An extrapolation approach using ...

  13. n-Alcohol/Water Partition Coefficients for Decachlorobiphenyl (PCB 209)

    Measurements of n-octanol/water partition coefficients (Kow) for highly hydrophobic chemicals are extremely difficult and are rarely made, in part due to the large volumes of water typically needed to quantify these compounds in the aqueous phase. An extrapolation approach using ...

  14. Association of nicotinamide with parabens: effect on solubility, partition and transdermal permeation.

    Nicoli, Sara; Zani, Franca; Bilzi, Stefania; Bettini, Ruggero; Santi, Patrizia


    Nicotinamide is a hydrophilic molecule, freely soluble in water, used as cosmetic active ingredient for its moisturizing and depigmenting properties. Moreover it has the ability to augment the solubility of poorly water-soluble molecules acting as a hydrotrope. The aim of this work was to study the effect of nicotinamide on the transdermal permeation of methyl, ethyl, propyl and butyl paraben. Parabens flux was measured in vitro in the presence and absence of different amounts of nicotinamide. From solubility studies it was found that nicotinamide forms one or more complexes with methyl, propyl and butyl paraben in water, even though with low stability constants. The interaction of ethyl paraben seems to be less easy to explain. The association of nicotinamide with parabens causes a significant reduction of the permeability coefficients of these preservatives through rabbit ear skin, caused by a reduction of the stratum corneum/vehicle partition coefficient. The effects of nicotinamide on parabens solubility, permeation and partitioning are potentially very interesting because nicotinamide can facilitate paraben dissolution in aqueous media (solutions, gels), reduce parabens partitioning in the oily phase thus guaranteeing an effective concentration in the water phase in emulsion and reduce transdermal penetration, thus reducing the toxicological risk.

  15. Evaluation of solubility and partition properties of ampicillin-based ionic liquids.

    Florindo, Catarina; Araújo, João M M; Alves, Filipa; Matos, Carla; Ferraz, Ricardo; Prudêncio, Cristina; Noronha, João Paulo; Petrovski, Željko; Branco, Luís; Rebelo, Luís Paulo N; Marrucho, Isabel M


    In order to overcome the problems associated with low water solubility, and consequently low bioavailability of active pharmaceutical ingredients (APIs), herein we explore a modular ionic liquid synthetic strategy for improved APIs. Ionic liquids containing L-ampicillin as active pharmaceutical ingredient anion were prepared using the methodology developed in our previous work, using organic cations selected from substituted ammonium, phosphonium, pyridinium and methylimidazolium salts, with the intent of enhancing the solubility and bioavailability of L-ampicillin forms. In order to evaluate important properties of the synthesized API-ILs, the water solubility at 25 °C and 37 °C (body temperature) as well as octanol-water partition coefficients (Kow's) and HDPC micelles partition at 25 °C were measured. Critical micelle concentrations (CMC's) in water at 25 °C and 37 °C of the pharmaceutical ionic liquids bearing cations with surfactant properties were also determined from ionic conductivity measurements.

  16. A novel method for measuring polymer-water partition coefficients.

    Zhu, Tengyi; Jafvert, Chad T; Fu, Dafang; Hu, Yue


    Low density polyethylene (LDPE) often is used as the sorbent material in passive sampling devices to estimate the average temporal chemical concentration in water bodies or sediment pore water. To calculate water phase chemical concentrations from LDPE concentrations accurately, it is necessary to know the LDPE-water partition coefficients (KPE-w) of the chemicals of interest. However, even moderately hydrophobic chemicals have large KPE-w values, making direct measurement experimentally difficult. In this study we evaluated a simple three phase system from which KPE-w can be determined easily and accurately. In the method, chemical equilibrium distribution between LDPE and a surfactant micelle pseudo-phase is measured, with the ratio of these concentrations equal to the LDPE-micelle partition coefficient (KPE-mic). By employing sufficient mass of polymer and surfactant (Brij 30), the mass of chemical in the water phase remains negligible, albeit in equilibrium. In parallel, the micelle-water partition coefficient (Kmic-w) is determined experimentally. KPE-w is the product of KPE-mic and Kmic-w. The method was applied to measure values of KPE-w for 17 polycyclic aromatic hydrocarbons, 37 polychlorinated biphenyls, and 9 polybrominated diphenylethers. These values were compared to literature values. Mass fraction-based chemical activity coefficients (γ) were determined in each phase and showed that for each chemical, the micelles and LDPE had nearly identical affinity.

  17. Xenon tissue/blood partition coefficient for pig urinary bladder

    Nielsen, K K; Bülow, J; Nielsen, S L


    In four landrace pigs the tissue/blood partition coefficient (lambda) for xenon (Xe) for the urinary bladder was calculated after chemical analysis for lipid, water and protein content and determination of the haematocrit. The coefficients varied from bladder to bladder owing to small differences...... in both the haematocrit and tissue composition. In Xe washout studies of the blood flow of the urinary bladder, we recommend calculating the lambda for Xe from the actual haematocrit and from the median value of tissue composition found in the present study....

  18. Association of the blood/air partition coefficient of 1,3-butadiene with blood lipids and albumin.

    Lin, Yu-Sheng; Smith, Thomas J; Wypij, David; Kelsey, Karl T; Sacks, Frank M


    Pulmonary gas uptake is a function of the blood solubility of a vapor, indicated by the blood/air partition coefficient. We hypothesized that blood lipid compositions are associated with the blood/air partition coefficients of lipophilic toxic vapors such as 1,3-butadiene. Our goal was to investigate cross-sectional and longitudinal relationships of blood triglycerides, total cholesterol, and albumin to the blood/air partition coefficient of butadiene. We collected blood samples from 24 subjects at three time points: a fasting baseline and 2 and 4 hr after drinking a standardized high-fat milk shake (107 g fat, 80 g sugar, and 27 g protein). The blood/air partition coefficient was determined using the closed vial-equilibrium technique. Triglycerides and total cholesterol were analyzed by an enzymatic method, and albumin was analyzed with an immunoassay technique. We used multiple linear regression and general linear models to examine the cross-sectional and longitudinal relationship, respectively. The results showed that the blood/air partition coefficient of butadiene was cross-sectionally associated only with triglycerides at baseline, and longitudinally related to baseline triglycerides, total cholesterol, and the change in triglycerides over time. The blood/air partition coefficient of butadiene increased, on average, by approximately 20% and up to 40% for subjects with borderline higher triglyceride levels after ingestion of a standardized milk shake. In addition, a time factor beyond lipids was also significant in predicting the blood/air partition coefficient of butadiene. This may represent the effects of other unmeasured parameters related to time or time of day on the blood/air partition coefficient of butadiene. Because the blood/air partition coefficient is a major determinant of gas uptake, ingestion of a high fat meal before this type of exposure may significantly increase an individual's absorbed dose, possibly increasing the risk of adverse effects.

  19. Application of New Partition Coefficients to Modeling Plagioclase

    Fagan, A. L.; Neal, C. R.; Rapp, J. F.; Draper, D. S.; Lapen, T. J.


    Previously, studies that determined the partition coefficient for an element, i, between plagioclase and the residual basaltic melt (Di plag) have been conducted using experimental conditions dissimilar from the Moon, and thus these values are not ideal for modeling plagioclase fractionation in a lunar system. However, recent work [1] has determined partition coefficients for plagioclase at lunar oxygen fugacities, and resulted in plagioclase with Anorthite contents =An90; these are significantly more calcic than plagioclase in previous studies, and the An content has a profound effect on partition coefficient values [2,3]. Plagioclase D-values, which are dependent on the An content of the crystal [e.g., 2-6], can be determined using published experimental data and the correlative An contents. Here, we examine new experimental data from [1] to ascertain their effect on the calculation of equilibrium liquids from Apollo 16 sample 60635,2. This sample is a coarse grained, subophitic impact melt composed of 55% plagioclase laths with An94.4-98.7 [7,8], distinctly more calcic than of previous partition coefficient studies (e.g., [3-6, 9-10]). Sample 60635,2 is notable as having several plagioclase trace element analyses containing a negative Europium anomaly (-Eu) in the rare-earth element (REE) profile, rather than the typical positive Eu anomaly (+Eu) [7-8] (Fig. 1). The expected +Eu is due to the similarity in size and charge with Ca2+, thereby allowing Eu2+ to be easily taken up by the plagioclase crystal structure, in contrast to the remaining REE3+. Some 60635,2 plagioclase crystals only have +Eu REE profiles, some only have -Eu REE profiles, and some +Eu and -Eu analyses in different areas on a single crystal [7, 8]. Moreover, there does not seem to be any core-rim association with the +Eu or -Eu analyses, nor does there appear to be a correlation between the size, shape, or location of a particular crystal within the sample and the sign of its Eu anomaly, which

  20. Prediction of Partition Coefficients of Organic Compounds for SPME/PDMS

    Liao Hsuan-Yu


    Full Text Available The partition coefficients of 51 organic compounds between SPME/PDMS and gas were compiled from the literature sources in this study. The effect of physicochemical properties and descriptors on the partitioning process of partition coefficients was explicated by the correlation analysis. The PDMS-gas partition coefficients were well correlated to the molecular weight of organic compounds (r = 0.832, p < 0.05. An empirical model, consisting of the molecular weight and the polarizability, was developed to appropriately predict the partition coefficients of organic compounds. The empirical model for estimating the PDMS-gas partition coefficient will contribute to the practical applications of the SPME technique.

  1. Salting-out phenomenon and 1-octanol/water partition coefficient of metalaxyl pesticide.

    Saab, J; Bassil, G; Abou Naccoul, R; Stephan, J; Mokbel, I; Jose, J


    In this paper, we present the effect of inorganic cations such as Na+, K+, Ca2+, Mg2+ on the salting-out phenomenon of metalaxyl from pure water to aqueous salt solutions. Moreover the 1-octanol/water partition coefficient in pure water is presented. To accomplish this, aqueous solubility of metalaxyl was determined in pure water, in different salt solution (NaCl, KCl, CaCl2 and MgCl2), and at different concentration level ranging from 0.01 to 1.5 M. The 1-octanol/water partition coefficient was determined using the static shake-flask method. Solubility was determined using dynamic saturation method for pure water in the range of 298.15-325.15 K and at 298.15 K for different salt solutions. The solubility value in pure water for studied interval was found constant (m=3.118×10(-2) mol kg(-1)). Solubility values were used to calculate the standard molar Gibbs free energy of dissolution (ΔsolG°) and transfer (ΔtrG°) at 298.15 K. The values of ΔtrG° from pure to all studied aqueous salt solutions did not exceed 2 kJ mol(-1), the value of ΔsolG° of dissolution is 18.5 ±0.72 kJ mol(-1). The 1-octanol/water partition coefficient in pure water log Ko/w is equal to 1.69. The obtained results confirm the classification of the neutral metalaxyl as a slightly hydrophobic molecule.

  2. Determining the Metal/Silicate Partition Coefficient of Germanium: Implications for Core and Mantle Differentiation.

    King, C.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.


    Currently there are several hypotheses for the thermal state of the early Earth. Some hypothesize a shallow magma ocean, or deep magma ocean, or heterogeneous accretion which requires no magma ocean at all. Previous models are unable to account for Ge depletion in Earth's mantle relative to CI chondrites. In this study, the element Ge is used to observe the way siderophile elements partition into the metallic core. The purpose of this research is to provide new data for Ge and to further test these models for Earth's early stages. The partition coefficients (D(sub Ge) = c(sub metal)/c(sub silicate), where D = partition coefficient of Ge and c = concentration of Ge in the metal and silicate, respectively) of siderophile elements were studied by performing series of high pressure, high temperature experiments. They are also dependent on oxygen fugacity, and metal and silicate composition. Ge is a moderately siderophile element found in both the mantle and core, and has yet to be studied systematically at high temperatures. Moreover, previous work has been limited by the low solubility of Ge in silicate melts (less than 100 ppm and close to detection limits for electron microprobe analysis). Reported here are results from 14 experiments studying the partitioning of Ge between silicate and metallic liquids. The Ge concentrations were then analyzed using Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICP-MS) which is sensitive enough to detect ppm levels of Ge in the silicate melt.

  3. Correlativity Between Solubility O/W Partition Coefficients of Berbenine Hydrochloride and Intestinal Absorption in Rats in Situ%盐酸小檗碱的溶解度及油水分配系数与大鼠在体肠吸收之间的相关性研究

    黄嗣航; 龙晓英; 袁飞; 陈莉; 罗明磊; 蔡宝玲; 刘昌顺


    OBJECTIVE To determine the equilibrium solubility and the partition coefficient of Berbenine Hydrochloride (BH) and to evaluate its intestinal absorption characteristic. METHODS The solubility and partition coefficient of BH were measured by shaking flask-UV spectrophotometry. The absorptions of three concentrations(50, 100, 150 ug-inL‐1) of BH in different intestinal segments were studied by phenol red assay and gravimetry. The concentrations of BH and phenol red were determined by HPLC. RESULTS The solubility of BH was increased with the pH increase of the buffer solution, and oil-water partition coefficient was decreased with increasing the pH of the buffer solution. Phenol red assay was better to reduce experimental error than gravimetry. There was positive correlation between the Permeability coefficient(Peff) of each intestine and concentrations of BH, and it has obvious difference(P<0.05) between the high concentration and low concentration. BH was well absorbed in jejunum at high and middle concentration, however, well absorption was observed in duodenum at low concentration. CONCLUSION In the experimental range, results of partition cofficients was in good accordance with predictive ones. BH was well absorbed at upper intestine than lower intestine over the concentration range. Extension of BH absorption time at upper intestine, could improve bioavailability.%目的 测定盐酸小檗碱(BH)的平衡溶解度和油水分配系数,并研究BH的大鼠肠吸收机制.方法 采用摇瓶-紫外分光光度法测定平衡溶解度及油水分配系数;分别采用酚红法和重量法校正灌流液体积,研究BH 3个剂量组(50,100,150μg·mL-1)在大鼠不同肠段的吸收情况.采用HIPLC对灌流前后BH、酚红含量进行测定.结果 BHI溶解度随pH值的增加而增加,油水分配系数则相反;酚红法较重量法能更好的减少实验误差,BH在低、中、高3个浓度下,各肠段的有效渗透系数(Peff)有上升趋势,且

  4. Determination of partition and diffusion coefficients of formaldehyde in selected building materials and impact of relative humidity.

    Xu, Jing; Zhang, Jianshun S; Liu, Xiaoyu; Gao, Zhi


    The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, "green" gypsum wallboard, and "green" carpet) under three relative humidity (RH) conditions (20%, 50%, and 70% RH). The "green" materials contained recycled materials and were friendly to environment. A dynamic dual-chamber test method was used. Results showed that a higher relative humidity led to a larger effective diffusion coefficient for two kinds of wallboards and carpet. The carpet was also found to be very permeable resulting in an effective diffusion coefficient at the same order of magnitude with the formaldehyde diffusion coefficient in air. The partition coefficient (K(ma)) of formaldehyde in conventional wallboard was 1.52 times larger at 50% RH than at 20% RH, whereas it decreased slightly from 50% to 70% RH, presumably due to the combined effects of water solubility of formaldehyde and micro-pore blocking by condensed moisture at the high RH level. The partition coefficient of formaldehyde increased slightly with the increase of relative humidity in "green" wallboard and "green" carpet. At the same relative humidity level, the "green" wallboard had larger partition coefficient and effective diffusion coefficient than the conventional wallboard, presumably due to the micro-pore structure differences between the two materials. The data generated could be used to assess the sorption effects of formaldehyde on building materials and to evaluate its impact on the formaldehyde concentration in buildings.

  5. 非布索坦平衡溶解度、表观油水分配系数及解离常数的测定%Determination of equilibrium solubility, apparent oil/water partition coefficient and dissociation constant of febuxostat

    张琪; 龚耘; 劳嘉泳; 张怡; 刘中秋; 蔡铮


    Objective: To determine equilibrium solubility ( Cs) , apparent oil/water partition coefficients (Papp) and dissociation constant (pKa) of febuxostat. Methods: Ultra performance liquid chromatography method was established to measure equilibrium solubility and logPapp of febuxostat at 37 ℃ in buffer solutions with various pH values. The pKa was determined by equilibrium solubility method and UV spectrophotometry, respectively. Results : With the rise of pH value, the Cs of febuxostat increased correspondingly, and apparent oil/water partition coefficients decreased inversely. When the pH value was 7.0, Cs was 246.4 mg·L and logPapp was 1. 19. The pKa values measured by equilibrium solubility method and UV spectrophotometry were 4. 08 and 4.07, respectively. Conclusion: Febuxostat is insoluble in acidic condition, very slight soluble in neutral condition, and slight soluble in alkaline condition; thus, it is unsuitable for intravenous injection because of the poor water solubility. However, oral administration is recommended due to, its proper lipophilicity and high permeability.%目的:测定非布索坦的平衡溶解度、表观油水分配系数及解离常数.方法:采用超高效液相色谱法测定非布索坦在37℃下不同pH值缓冲液中的平衡溶解度及表观油水分配系数,并分别通过平衡溶解度法及紫外吸光度法测定其解离常数.结果:非布索坦的平衡溶解度随缓冲液的pH值升高而增大,而表观油水分配系数则相应减小,当pH为7.0时,平衡溶解度为246.4 mg·L-1,表观油水分配系数为15.49;平衡溶解度法与紫外吸光度法测得的非布索坦的解离常数十分接近,分别为4.08与4.07.结论:非布索坦的溶解度较小,在酸性条件下几乎不溶,中性条件下极微溶解,碱性条件下微溶,不适合制备静注制剂,但由于其油水分配系数较高,具有较强的跨膜能力,可采用口服途径给药.

  6. Using measured octanol-air partition coefficients to explain environmental partitioning of organochlorine pesticides.

    Shoeib, Mahiba; Harner, Tom


    Octanol-air partition coefficients (Koa) were measured directly for 19 organochlorine (OC) pesticides over the temperature range of 5 to 35 degrees C. Values of log Koa at 25 degrees C ranged over three orders of magnitude, from 7.4 for hexachlorobenzene to 10.1 for 1,1-dichloro-2,2-bis(p-chlorophenyl) ethane. Measured values were compared to values calculated as KowRT/H (where R is the ideal gas constant [8.314 J mol(-1) K(-1)], T is absolute temperature, and H is Henry's law constant) were, in general, larger. Discrepancies of up to three orders of magnitude were observed, highlighting the need for direct measurements of Koa. Plots of Koa versus inverse absolute temperature exhibited a log-linear correlation. Enthalpies of phase transition between octanol and air (deltaHoa) were determined from the temperature slopes and were in the range of 56 to 105 kJ mol(-1) K(-1). Activity coefficients in octanol (gamma(o)) were determined from Koa and reported supercooled liquid vapor pressures (pL(o)), and these were in the range of 0.3 to 12, indicating near-ideal solution behavior. Differences in Koa values for structural isomers of hexachlorocyclohexane were also explored. A Koa-based model was described for predicting the partitioning of OC pesticides to aerosols and used to calculate particulate fractions at 25 and -10 degrees C. The model also agreed well with experimental results for several OC pesticides that were equilibrated with urban aerosols in the laboratory. A log-log regression of the particle-gas partition coefficient versus Koa had a slope near unity, indicating that octanol is a good surrogate for the aerosol organic matter.

  7. Partition coefficients for calcic plagioclase - Implications for Archean anorthosites

    Phinney, W. C.; Morrison, D. A.


    In most Archean cratons, cumulates of equant plagioclase megacrysts form anorthositic complexes, including those at Bad Vermilion Lake (Ontario). In this paper, partition coefficients (Ds) of REEs between natural high-Ca plagioclase megacrysts and their basaltic matrices were determined, using a multiple aliquot techique, and megacrystic plagioclases occurring in anorthosites were analyzed for the same components which, in conjunction with their Ds, were applied to calculations of melts in equilibrium with anorthosites. The REE's Ds were found to agree well with experimentally determined values and to predict equilibrium melts for Archean anorthosites that agree well with coeval basaltic flows and dikes. The Ds also appear to be valid for both the tholeiitic and alkali basalts over a wide range of mg numbers and REE concentrations. It is suggested that the moderately Fe-rich tholeiites that are hosts to plagioclase megacrysts in greenstone belts form the parental melts for megacrysts which make up the Bad Vermilion Lake Archean anorthositic complex.

  8. C-Depth Method to Determine Diffusion Coefficient and Partition Coefficient of PCB in Building Materials.

    Liu, Cong; Kolarik, Barbara; Gunnarsen, Lars; Zhang, Yinping


    Polychlorinated biphenyls (PCBs) have been found to be persistent in the environment and possibly harmful. Many buildings are characterized with high PCB concentrations. Knowledge about partitioning between primary sources and building materials is critical for exposure assessment and practical remediation of PCB contamination. This study develops a C-depth method to determine diffusion coefficient (D) and partition coefficient (K), two key parameters governing the partitioning process. For concrete, a primary material studied here, relative standard deviations of results among five data sets are 5%-22% for K and 42-66% for D. Compared with existing methods, C-depth method overcomes the inability to obtain unique estimation for nonlinear regression and does not require assumed correlations for D and K among congeners. Comparison with a more sophisticated two-term approach implies significant uncertainty for D, and smaller uncertainty for K. However, considering uncertainties associated with sampling and chemical analysis, and impact of environmental factors, the results are acceptable for engineering applications. This was supported by good agreement between model prediction and measurement. Sensitivity analysis indicated that effective diffusion distance, contacting time of materials with primary sources, and depth of measured concentrations are critical for determining D, and PCB concentration in primary sources is critical for K.

  9. Immiscible silicate liquid partition coefficients: implications for crystal-melt element partitioning and basalt petrogenesis

    Veksler, Ilya V.; Dorfman, Alexander M.; Danyushevsky, Leonid V.; Jakobsen, Jakob K.; Dingwell, Donald B.


    This study investigates partitioning of elements between immiscible aluminosilicate and borosilicate liquids using three synthetic mixtures doped with 32 trace elements. In order to get a good spatial separation of immiscible liquids, we employed a high-temperature centrifuge. Experiments were performed at 1,050-1,150°C, 1 atm, in sealed Fe and Pt containers. Quenched products were analysed by electron microprobe and LA ICP-MS. Nernst partition coefficients ( D’s) between the Fe-rich and Si-rich aluminosilicate immiscible liquids are the highest for Zn (3.3) and Fe (2.6) and the lowest for Rb and K (0.4-0.5). The plots of D values against ionic potential Z/r in all the compositions show a convex upward trend, which is typical also for element partitioning between immiscible silicate and salt melts. The results bear upon the speciation and structural position of elements in multicomponent silicate liquids. The ferrobasalt-rhyolite liquid immiscibility is observed in evolved basaltic magmas, and may play an important role in large gabbroic intrusions, such as Skaergaard, and during the generation of unusual lavas, such as ferropicrites.

  10. Effect of partition coefficient on microsegregation during solidification of aluminium alloys

    MH Avazkonandeh-Gharavol; M Haddad-Sabzevar; H Fredriksson


    In the modeling of microsegregation, the partition coefficient is usually calculated using data from the equilibrium phase diagrams. The aim of this study was to experimentally and theoretically analyze the partition coefficient in binary aluminum-copper alloys. The sam-ples were analyzed by differential thermal analysis (DTA), which were melted and quenched from different temperatures during solidifica-tion. The mass fraction and composition of phases were measured by image processing and scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDS) unit. These data were used to calculate as the experimental partition coefficients with four different methods. The experimental and equilibrium partition coefficients were used to model the concentration profile in the primary phase. The modeling results show that the profiles calculated by the experimental partition coefficients are more consistent with the experi-mental profiles, compared to those calculated using the equilibrium partition coefficients.

  11. Determination of partition coefficients of biomolecules in a microfluidic aqueous two phase system platform using fluorescence microscopy.

    Silva, D F C; Azevedo, A M; Fernandes, P; Chu, V; Conde, J P; Aires-Barros, M R


    Aqueous two phase systems (ATPS) offer great potential for selective separation of a wide range of biomolecules by exploring differences in molecular solubility in each of the two immiscible phases. However, ATPS use has been limited due to the difficulty in predicting the behavior of a given biomolecule in the partition environment together with the empirical and time-consuming techniques that are used for the determination of partition and extraction parameters. In this work, a fast and novel technique based on a microfluidic platform and using fluorescence microscopy was developed to determine the partition coefficients of biomolecules in different ATPS. This method consists of using a microfluidic device with a single microchannel and three inlets. In two of the inlets, solutions containing the ATPS forming components were loaded while the third inlet was fed with the FITC tagged biomolecule of interest prepared in milli-Q water. Using fluorescence microscopy, it was possible to follow the location of the FITC-tagged biomolecule and, by simply varying the pumping rates of the solutions, to quickly test a wide variety of ATPS compositions. The ATPS system is allowed 4min for stabilization and fluorescence micrographs are used to determine the partition coefficient.The partition coefficients obtained were shown to be consistent with results from macroscale ATPS partition. This process allows for faster screening of partition coefficients using only a few microliters of material for each ATPS composition and is amenable to automation. The partitioning behavior of several biomolecules with molecular weights (MW) ranging from 5.8 to 150kDa, and isoelectric points (pI) ranging from 4.7 to 6.4 was investigated, as well as the effect of the molecular weight of the polymer ATPS component. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. A simple method of determination of partition coefficient for biologically active molecules.

    Sersen, F


    A simple method is presented for the determination of partition coefficient of an effector between water environment and biological material, based on concentration-dependent effects. The method allows the determination of partition coefficients for biological objects such as algae, bacteria and other microorganisms.

  13. Experimental Method Development for Estimating Solid-phase Diffusion Coefficients and Material/Air Partition Coefficients of SVOCs

    The solid-phase diffusion coefficient (Dm) and material-air partition coefficient (Kma) are key parameters for characterizing the sources and transport of semivolatile organic compounds (SVOCs) in the indoor environment. In this work, a new experimental method was developed to es...

  14. Siderophile elements in the upper mantle of the Earth: New clues from metal-silicate partition coefficients

    Holzheid, A.; Borisov, A.; Palme, H.


    New, precise data on the solubilities of Ni, Co, and Mo in silicate melts at 1400 C and fO2 from IW to IW-2 are presented. The results suggest NiO, CoO as stable species in the melt. No evidence for metallic Ni or Co was found. Equilibrium was ensured by reversals with initially high Ni and Co in the glass. Mo appears to change oxidation state at IW-1, from MoO3 to MoO2. Metal-silicate partition coefficients calculated from these data and recent data on Pd indicate similar partition coefficients for Pd and Mo at the conditions of core formation. This unexpected result constrains models of core formation in the Earth.

  15. Trophic Magnification of PCBs and Its Relationship to the Octanol−Water Partition Coefficient

    We investigated polychlorinated biphenyl (PCB) bioaccumulation relative to octanol-water partition coefficient (KOW) and organism trophic position (TP) at the Lake Hartwell Superfund (South Carolina, USA). We measured PCBs (127 congeners) and stable isotopes (δ15...

  16. Use of partition coefficients in flow-limited physiologically-based pharmacokinetic modeling.

    Thompson, Matthew D; Beard, Daniel A; Wu, Fan


    Permeability-limited two-subcompartment and flow-limited, well-stirred tank tissue compartment models are routinely used in physiologically-based pharmacokinetic modeling. Here, the permeability-limited two-subcompartment model is used to derive a general flow-limited case of a two-subcompartment model with the well-stirred tank being a specific case where tissue fractional blood volume approaches zero. The general flow-limited two-subcompartment model provides a clear distinction between two partition coefficients typically used in PBPK: a biophysical partition coefficient and a well-stirred partition coefficient. Case studies using diazepam and cotinine demonstrate that, when the well-stirred tank is used with a priori predicted biophysical partition coefficients, simulations overestimate or underestimate total organ drug concentration relative to flow-limited two-subcompartment model behavior in tissues with higher fractional blood volumes. However, whole-body simulations show predicted drug concentrations in plasma and lower fractional blood volume tissues are relatively unaffected. These findings point to the importance of accurately determining tissue fractional blood volume for flow-limited PBPK modeling. Simulations using biophysical and well-stirred partition coefficients optimized with flow-limited two-subcompartment and well-stirred models, respectively, lead to nearly identical fits to tissue drug distribution data. Therefore, results of whole-body PBPK modeling with diazepam and cotinine indicate both flow-limited models are appropriate PBPK tissue models as long as the correct partition coefficient is used: the biophysical partition coefficient is for use with two-subcompartment models and the well-stirred partition coefficient is for use with the well-stirred tank model.

  17. Partition coefficients of Hf, Zr, and REE between phenocrysts and groundmasses

    Fujimaki, H.; Tatsumoto, M.; Aoki, K.-I.


    Partition coefficients of Hf, Zr, and REE between olivine, orthopyroxene, clinopyroxene, plagioclase, garnet, amphibole, ilmenite, phlogopite, and liquid are presented. Samples consist of megacrysts in kimberlite, phenocrysts in alkaline basalts, tholeiitic basalts and andesitic to dacitic rocks, and synthetic garnet and clinopyroxene in Hawaiian tholeiites. The Hf-Lu and Zr-Lu elemental fractionations are as large as the Lu-Sm or Lu-Nd fractionation. The Hf and Zr partition coefficients between mafic phenocrysts and liquids are smaller than the Lu partition coefficients, but are similar to the Nd or Sm partition coefficients. The Hf and Zr partition coefficients between ilmenite, phlogopite, and liquid are larger than the Lu partition coefficients for these minerals and their corresponding liquids. The Hf-Zr elemental fractionation does not occur except for extreme fractionation involving Zr-minerals and extremely low fO2. These data have an important bearing on chronological and petrogenetic tracer studies involving the Lu-Hf isotopic system.

  18. Predicting solute partitioning in lipid bilayers: Free energies and partition coefficients from molecular dynamics simulations and COSMOmic

    Jakobtorweihen, S., E-mail:; Ingram, T.; Gerlach, T.; Smirnova, I. [Institute of Thermal Separation Processes, Hamburg University of Technology, Eissendorfer Str. 38, 21073 Hamburg (Germany); Zuniga, A. Chaides; Keil, F. J. [Institute of Chemical Reaction Engineering, Hamburg University of Technology, Eissendorfer Str. 38, 21073 Hamburg (Germany)


    Quantitative predictions of biomembrane/water partition coefficients are important, as they are a key property in pharmaceutical applications and toxicological studies. Molecular dynamics (MD) simulations are used to calculate free energy profiles for different solutes in lipid bilayers. How to calculate partition coefficients from these profiles is discussed in detail and different definitions of partition coefficients are compared. Importantly, it is shown that the calculated coefficients are in quantitative agreement with experimental results. Furthermore, we compare free energy profiles from MD simulations to profiles obtained by the recent method COSMOmic, which is an extension of the conductor-like screening model for realistic solvation to micelles and biomembranes. The free energy profiles from these molecular methods are in good agreement. Additionally, solute orientations calculated with MD and COSMOmic are compared and again a good agreement is found. Four different solutes are investigated in detail: 4-ethylphenol, propanol, 5-phenylvaleric acid, and dibenz[a,h]anthracene, whereby the latter belongs to the class of polycyclic aromatic hydrocarbons. The convergence of the free energy profiles from biased MD simulations is discussed and the results are shown to be comparable to equilibrium MD simulations. For 5-phenylvaleric acid the influence of the carboxyl group dihedral angle on free energy profiles is analyzed with MD simulations.

  19. Modeling flavor release from aqueous sucrose solutions, using mass transfer and partition coefficients

    Nahon, D.F.; Harrison, M.; Roozen, J.P.


    The penetration theory of interfacial mass transfer was used to model flavor release from aqueous solutions containing different concentrations of sucrose. The mass transfer coefficient and the gas/solution partition coefficient are the main factors of the model influencing the release in time. Para

  20. Determination of air-loop volume and radon partition coefficient for measuring radon in water sample.

    Lee, Kil Yong; Burnett, William C

    A simple method for the direct determination of the air-loop volume in a RAD7 system as well as the radon partition coefficient was developed allowing for an accurate measurement of the radon activity in any type of water. The air-loop volume may be measured directly using an external radon source and an empty bottle with a precisely measured volume. The partition coefficient and activity of radon in the water sample may then be determined via the RAD7 using the determined air-loop volume. Activity ratios instead of absolute activities were used to measure the air-loop volume and the radon partition coefficient. In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10-30 °C and compared the values to those calculated from the well-known Weigel equation. The results were within 5 % variance throughout the temperature range. We also applied the approach for measurement of the radon partition coefficient in synthetic saline water (0-75 ppt salinity) as well as tap water. The radon activity of the tap water sample was determined by this method as well as the standard RAD-H2O and BigBottle RAD-H2O. The results have shown good agreement between this method and the standard methods.

  1. Methamphetamine absorption by skin lipids: accumulated mass, partition coefficients, and the influence of fatty acids.

    Parker, K; Morrison, G


    Occupants of former methamphetamine laboratories, often residences, may experience increased exposure through the accumulation of the methamphetamine in the organic films that coat skin and indoor surfaces. The objectives of this study were to determine equilibrium partition coefficients of vapor-phase methamphetamine with artificial sebum (AS-1), artificial sebum without fatty acids (AS-2), and real skin surface films, herein called skin oils. Sebum and skin oil-coated filters were exposed to vapor-phase methamphetamine at concentrations ranging from 8 to 159 ppb, and samples were analyzed for exposure time periods from 2 h to 60 days. For a low vapor-phase methamphetamine concentration range of ~8-22 ppb, the equilibrium partition coefficient for AS-1 was 1500 ± 195 μg/g/ppb. For a high concentration range of 98-112 ppb, the partition coefficient was lower, 459 ± 80 μg/g/ppb, suggesting saturation of the available absorption capacity. The low partition coefficient for AS-2 (33 ± 6 μg/g/ppb) suggests that the fatty acids in AS-1 and skin oil are responsible for much high partition coefficients. We predict that the methamphetamine concentration in skin lipids coating indoor surfaces can exceed recommended surface remediation standards even for air concentrations well below 1 ppb.

  2. Phase partitioning and solubility of iron in natural seawater controlled by dissolved organic matter

    Chen, Min; Wang, Wen-Xiong; Guo, Laodong


    The phase partitioning and solubility of Fe as well as its relationship with marine dissolved organic matter (DOM) in different natural seawater and phytoplankton cultures were examined using radiotracer and ultrafiltration techniques to better understand Fe biogeochemical cycling and its biological availability in the ocean. Fe solubility in seawaters was related to the filter's cutoff, with the Fe solubility in the Complexation of organic ligands with Fe appeared to be Fe-specific or Fe preferential. Our results highlight quantitatively the importance of DOM in controlling Fe solubility in seawater. Further studies are needed to elucidate the interrelationship between the biogeochemical cycles of Fe and the chemistry of DOM in the ocean.

  3. Molecular Descriptors Family on Structure Activity Relationships 6. Octanol-Water Partition Coefficient of Polychlorinated Biphenyls

    Lorentz JÄNTSCHI


    Full Text Available Octanol-water partition coefficient of two hundred and six polychlorinated biphenyls was model by the use of an original method based on complex information obtained from compounds structure. The regression analysis shows that best results are obtained in four-varied model (r2 = 0.9168. The prediction ability of the model was studied through leave-one-out analysis (r2cv(loo = 0.9093 and in training and test sets analysis. Modeling the octanol-water partition coefficient of polychlorinated biphenyls by integration of complex structural information provide a stable and performing four-varied model, allowing us to make remarks about relationship between structure of polychlorinated biphenyls and associated octanol-water partition coefficients.

  4. octanol/water partition coefficient using solvation free energy and solvent-accessible surface area


    The regression model for octanol/water partition coefficients (Kow ), is founded with only two molecular descriptors available through quantum chemical calculations: solvation free energy (△ Gs ), and solvent-accessible surface area (SASA). For the properties of 47 organic compounds from 17 types, the model gives a oonection coefficient (adjusted for degrees of freedom) of 0.959 and a standard error of 0.277 log unit. It is a suitable way to predict the partition properties that are related to solute-solvent interactions in the water phase.

  5. Regional partition coefficient of water in patients with cerebrovascular disease and its effect on rCBF assessment

    Hirata, Kenji; Hattori, Naoya; Katoh, Chietsugu; Shiga, Tohru; KURODA, Satoshi; Kubo, Naoki; Usui, Reiko; Kuge, Yuji; Tamaki, Nagara


    Objective: Cerebral blood flow (CBF) estimation with C15O2 PET usually assumes a single tissue compartment model and a fixed brain-blood partition coefficient of water. However, the partition coefficient may change in pathological conditions. The purpose of this study was to investigate the changes of partition coefficient of water in pathological regions and its effect on regional CBF assessment. Methods: Study protocol included 22 patients with occlusive cerebrovascular disease to compare p...

  6. Partition coefficients for Al, Ca, Ti, Cr, and Ni in olivine obtained by melting experiment on an LL6 chondrite

    Miyamoto, M.; Mikouchi, T.; Mckay, G. A.


    We report the partition coefficients for Ca, Al, Ti, Cr, and Ni in olivine obtained through a series of melting experiments on an LL6 chondrite under varying conditions of temperature and oxygen fugacity. It is necessary to examine the variation of partition coefficients up to extremely reducing conditions in order to study meteoritic olivines. For Ca, Al, and Cr, the partition coefficients tend to decrease as temperature increases, but do not change even under extremely reducing conditions.


    Mbah, C. J.; C. E. Chigozie


    The objective of the present study was to investigate the effects of glycerol, propylene glycol, polysorbate-80 and sodium lauryl sulfate on the lipophilic character of quetiapine fumarate by studying their effects on the partition coefficient of the drug. The partition coefficient was evaluated in n-hexane-water system at room temperature. Of the vehicles investigated, it was found that glycerol, propylene glycol, polysorbate-80 decreased the partition coefficient of quetiapine fumarate, whi...

  8. Measurement of partition coefficients for selected polycyclic aromatic hydrocarbons between isolated plant cuticles and water.

    Kim, Su-Jin; Lee, Hwang; Kwon, Jung-Hwan


    Partition coefficients between plant cuticles and water (Kcutw) were measured for 10 selected polycyclic aromatic hydrocarbons (PAHs) to evaluate the sorption capacity of plant cuticular layers for hydrophobic organic chemicals. The partitioning properties of PAHs between cuticles and water were evaluated by using (1) isolated cuticular layers and (2) leaf homogenate. The abaxial and adaxial cuticular layers of Euonymus japonicus were isolated by enzymatic digestion. A third-phase partitioning method using poly(dimethylsiloxane) (PDMS) was used to obtain Kcutw. The Kcutw values for the selected PAHs showed no significant differences between the abaxial and adaxial cuticular layers and ranged between 10(4.1) and 10(7.6). These values are close to or slightly higher than their 1-octanol/water partition coefficient (log Kow), indicating high sorption capacity of plant cuticles. On the contrary, partition coefficients between the lipid tissues of homogenized leaves and water were lower than those obtained using isolated cuticular layers by factors of 3.7-190, which is likely due to the breakdown of lipid layers. This indicates that the sorption of hydrophobic organic chemicals by plant leaves is better evaluated using isolated cuticles and that the sorption potential of plant leaves may be underestimated when leaf homogenates are used. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Distribution ratio, distribution constant and partition coefficient. Countercurrent chromatography retention of benzoic acid.

    Berthod, Alain; Mekaoui, Nazim


    There is some confusion in chromatography between terms such as solute distribution ratio, distribution constant and partition coefficient. These terms are very precisely defined in the field of liquid-liquid systems and liquid-liquid extraction as well as in the field of chromatography with sometimes conflicting definitions. Countercurrent chromatography (CCC) is a chromatographic technique in which the stationary phase is a support-free liquid. Since the mobile phase is also liquid, biphasic liquid systems are used. This work focuses on the exact meaning of the terms since there are consequences on experimental results. The retention volumes of solutes in CCC are linearly related to their distribution ratios. The partition coefficient that should be termed (IUPAC recommendation) distribution constant is linked to a single definite species. Using benzoic acid that can dimerize in heptane and ionize in aqueous phase and an 18 mL hydrodynamic CCC column, the role and relationships between parameters and the consequences on experimental peak position and shape are discussed. If the heptane/water distribution constant (marginally accepted to be called partition coefficient) of benzoic acid is 0.2 at 20 °C and can be tabulated in books, its CCC measured distribution ratio or distribution coefficient can change between zero (basic aqueous mobile phase) and more than 25 (acidic aqueous mobile phase and elevated concentration). Benzoic acid distribution ratio and partition coefficient coincide only when both dimerization and ionization are quenched, i.e. at very low concentration and pH 2. It is possible to quench dimerization adding butanol in the heptane/water system. However, butanol additions also affect the partition coefficient of benzoic acid greatly by increasing it.

  10. Simple Method to Determine the Partition Coefficient of Naphthenic Acid in Oil/Water

    Bitsch-Larsen, Anders; Andersen, Simon Ivar


    The partition coefficient for technical grade naphthenic acid in water/n-decane at 295 K has been determined (K-wo = 2.1 center dot 10(-4)) using a simple experimental technique with large extraction volumes (0.09 m(3) of water). Furthermore, nonequilibrium values at different pH values are prese...

  11. Blood gas partition coefficient and pulmonary extraction ratio for propofol in goats and pigs.

    Grossherr, M; Hengstenberg, A; Dibbelt, L; Igl, B-W; Noel, R; Knesebeck, A v d; Schmucker, P; Gehring, H


    The interpretation of continuously measured propofol concentration in respiratory gas demands knowledge about the blood gas partition coefficient and pulmonary extraction ratio for propofol. In the present investigation we compared both variables for propofol between goats and pigs during a propofol anaesthesia. In ten goats and ten pigs, expired alveolar gas and arterial and mixed venous blood samples were simultaneously drawn during total intravenous anaesthesia with propofol. The blood gas partition coefficient and pulmonary extraction ratio were calculated for both species. Non-parametric methods were used for statistical inference. The blood gas partition coefficient ranged between 7000 and 646,000 for goats and between 17,000 and 267,000 for pigs. The pulmonary extraction ratio ranged between 32.9% and 98.1% for goats and was higher for pigs, which ranged between -106.0% and 39.0%. The blood gas partition coefficient for propofol exceeded those for other known anaesthetic compounds so that it takes longer to develop a steady-state. The different pulmonary extraction rates in two species suggest that there are different ways to distribute propofol during the lung passage on its way from the blood to breathing gas. This species-specific difference has to be considered for methods using the alveolar gas for monitoring the propofol concentration in plasma.

  12. ClogP(alk): a method for predicting alkane/water partition coefficient.

    Kenny, Peter W; Montanari, Carlos A; Prokopczyk, Igor M


    Alkane/water partition coefficients (P(alk)) are less familiar to the molecular design community than their 1-octanol/water equivalents and access to both data and prediction tools is much more limited. A method for predicting alkane/water partition coefficient from molecular structure is introduced. The basis for the ClogP(alk) model is the strong (R² = 0.987) relationship between alkane/water partition coefficient and molecular surface area (MSA) that was observed for saturated hydrocarbons. The model treats a molecule as a perturbation of a saturated hydrocarbon molecule with the same MSA and uses increments defined for functional groups to quantify the extent to which logP(alk) is perturbed by the introduction each functional group. Interactions between functional groups, such as intramolecular hydrogen bonds are also parameterized within a perturbation framework. The functional groups and interactions between them are specified substructurally in a transparent and reproducible manner using SMARTS notation. The ClogP(alk) model was parameterized using data measured for structurally prototypical compounds that dominate the literature on alkane/water partition coefficients and then validated using an external test set of 100 alkane/water logP measurements, the majority of which were for drugs.

  13. Information-theoretic indices usage for the prediction and calculation of octanol-water partition coefficient.

    Persona, Marek; Kutarov, Vladimir V; Kats, Boris M; Persona, Andrzej; Marczewska, Barbara


    The paper describes the new prediction method of octanol-water partition coefficient, which is based on molecular graph theory. The results obtained using the new method are well correlated with experimental values. These results were compared with the ones obtained by use of ten other structure correlated methods. The comparison shows that graph theory can be very useful in structure correlation research.

  14. Measurement and analysis of the mannitol partition coefficient in sucrose crystallization under simulated industrial conditions

    Mannitol is a major deterioration product of Leuconstoc mesenteroides bacterial deterioration of both sugarcane and sugar beet. The effect of crystallization conditions on the mannitol partition coefficient (Keff) between impure sucrose syrup and crystal has been investigated in a batch laboratory c...

  15. Determination of Partition Coefficients of Selected Model Migrants between Polyethylene and Polypropylene and Nanocomposite Polypropylene

    Pablo Otero-Pazos


    Full Text Available Studies on nanoparticles have focused the attention of the researchers because they can produce nanocomposites that exhibit unexpected hybrid properties. Polymeric materials are commonly used in food packaging, but from the standpoint of food safety, one of the main concerns on the use of these materials is the potential migration of low molecular substances from the packaging into the food. The key parameters of this phenomenon are the diffusion and partition coefficients. Studies on migration from food packaging with nanomaterials are very scarce. This study is focused on the determination of partition coefficients of different model migrants between the low-density polyethylene (LDPE and polypropylene (PP and between LDPE and nanocomposite polypropylene (naPP. The results show that the incorporation of nanoparticles in polypropylene increases the mass transport of model migrants from LDPE to naPP. This quantity of migrants absorbed into PP and naPP depends partially on the nature of the polymer and slightly on the chemical features of the migrant. Relation (RPP/naPP between partition coefficient KLDPE/PP and partition coefficient KLDPE/naPP at 60°C and 80°C shows that only BHT at 60°C has a RPP/naPP less than 1. On the other hand, bisphenol A has the highest RPP/naPP with approximately 50 times more.

  16. Systematic computation of phase partition and solubilities in phase transfer catalytic processes

    Piccolo, Chiara; Piccone, Patrick M.; Shaw, Andrew

    Phase transfer catalysis (PTC) is a general methodology applicable to a great variety of reactions in which inorganic anions react with organic compounds. In PTC, reactions are performed in heterogeneous two phase systems in which there is a negligible mutual solubility of the phases. One aqueous...... phase serves as a reservoir of reacting anions, whereas organic reactants are located in a second, organic phase. The key feature of this approach is the use of a catalytic amount of an organic soluble cation (often a quaternary ammonium cation) to induce solubilization of the reactive anion...... in the organic phase while trying to minimize the partition of the product anion. Therefore the determination of the solubility and the related equilibrium partitioning of the active and inactive form of the PT catalyst between the two phases is critical for the design of successful phase transfer catalytic...

  17. Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.

    Padró, Juan M; Pellegrino Vidal, Rocío B; Reta, Mario


    The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium bromide, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium dicyanamide, were accurately measured. In this way, we extended our database of partition coefficients in room-temperature ionic liquids previously reported. We employed the solvation parameter model with different probe molecules (the training set) to elucidate the chemical interactions involved in the partition process and discussed the most relevant differences among the three types of ionic liquids. The multiparametric equations obtained with the aforementioned model were used to predict the partition coefficients for compounds (the test set) not present in the training set, most being of biological and pharmacological interest. An excellent agreement between calculated and experimental log P IL/w values was obtained. Thus, the obtained equations can be used to predict, a priori, the extraction efficiency for any compound using these ionic liquids as extraction solvents in liquid-liquid extractions.

  18. Field determination and QSPR prediction of equilibrium-status soil/vegetation partition coefficient of PCDD/Fs.

    Li, Li; Wang, Qiang; Qiu, Xinghua; Dong, Yian; Jia, Shenglan; Hu, Jianxin


    Characterizing pseudo equilibrium-status soil/vegetation partition coefficient KSV, the quotient of respective concentrations in soil and vegetation of a certain substance at remote background areas, is essential in ecological risk assessment, however few previous attempts have been made for field determination and developing validated and reproducible structure-based estimates. In this study, KSV was calculated based on measurements of seventeen 2,3,7,8-substituted PCDD/F congeners in soil and moss (Dicranum angustum), and rouzi grass (Thylacospermum caespitosum) of two background sites, Ny-Ålesund of the Arctic and Zhangmu-Nyalam region of the Tibet Plateau, respectively. By both fugacity modeling and stepwise regression of field data, the air-water partition coefficient (KAW) and aqueous solubility (SW) were identified as the influential physicochemical properties. Furthermore, validated quantitative structure-property relationship (QSPR) model was developed to extrapolate the KSV prediction to all 210 PCDD/F congeners. Molecular polarizability, molecular size and molecular energy demonstrated leading effects on KSV.

  19. Partition coefficients of organic compounds in new imidazolium based ionic liquids using inverse gas chromatography.

    Revelli, Anne-Laure; Mutelet, Fabrice; Jaubert, Jean-Noël


    Partition coefficients of organic compounds in four ionic liquids: 1-ethanol-3-methylimidazolium tetrafluoroborate, 1-ethanol-3-methylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium dimethylphosphate and 1-ethyl-3-methylimidazolium diethylphosphate were measured using inverse gas chromatography from 303.3 to 332.55K. The influence of gas-liquid and gas-solid interfacial adsorption of different solutes on ionic liquids was also studied. Most of the polar solutes were retained largely by partition while light hydrocarbons were retained predominantly by interfacial adsorption on the ionic liquids studied in this work. The solvation characteristics of the ionic liquids were evaluated using the Abraham solvation parameter model.

  20. The effect of glycerol, propylene glycol and polyethylene glycol 400 on the partition coefficient of benzophenone-3 (oxybenzone).

    Mbah, C J


    Sunscreen products are widely used to protect the skin from sun-related deleterious effects. The objective of the study was to investigate the potential effect of glycerol, propylene glycol and polyethylene glycol 400 on dermal absorption of oxybenzone by studying their effects on its partition coefficient. The partition coefficient was evaluated in a chloroform-water system at room temperature. It was found that glycerol and propylene glycol decreased the partition coefficient of oxybenzone, while an increase in partition coefficient was observed with polyethylene glycol 400. The findings suggest that polyethylene glycol 400 in contrast to glycerol and propylene glycol has the potential of increasing the vehicle-skin partition coefficient of oxybenzone when cosmetic products containing such an UV absorber are topically applied to the skin.

  1. Partition coefficient vs. binding constant: How best to assess molecular lipophilicity.

    Cevc, Gregor


    Partition coefficient, P, is the preferred descriptor of molecular lipo- or hydrophilicity, and thus of relationships between a solute (S, e.g., a drug), a polar medium (W, e.g., an aqueous buffer), and an essentially apolar, organic, medium or a drug carrier (O). The coefficient is commonly identified with the linear ratio of solute quantities in the two media, P=nSO/nSW, even to characterise solute association with or binding to a surface (e.g., of a HPLC column or a drug carrier). To check the latter practice correctness-and credibility of the prevailing P definition-this paper compares an ideal solute distribution between two separate homogeneous fluid media (i.e., partitioning) to solute association with a uniform surface immersed in one such medium (i.e., binding). This reveals that solute partitioning and binding fundamentally differ and can only exceptionally be described, or analysed, with similar equations. Nonlinearised formulae that describe partitioning (Eq. (9)) and binding (Eq. (11)) can yield similar lipophilicity descriptor values only if solute preparation is relatively dilute; employing a large organic medium fraction is helpful in this respect. Additional prerequisites for partitioning and binding models match are: 1:1 stoichiometry at the association maximum and identical interfacial area of solute and organic medium molecules. If these requirements are not met, binding model yields different, potentially somewhat higher, but more often up to >10 times lower results than partitioning model. The main reason is saturation of organic medium with solute molecules. Partitioning model excludes this phenomenon, which cannot always be prevented by focussing on dilute solute preparations. The current practice of using a linear model and approximate equations to study partitioning or binding can cause large errors (>10(3)×), and is one possible reason for the notoriously high experimental logP values scattering. The latter makes logP predictions more

  2. Partition Coefficients of Amino Acids, Peptides, and Enzymes in Dextran + Poly(Ethylene Glycol) + Water Aqueous Two-Phase Systems

    Kakisaka, Keijiro.; Shindo, Takashi.; Iwai, Yoshio.; Arai, Yasuhiko. (Kyushu University, Fukuoka (Japan). Department of Chemical Systems and Engineering)


    Partition coefficients are measured for five amino acids(aspartic acid, asparagine, methionine, cysteine and histidine) and tow peptides(glycyl-glycine and hexa-glycine) in dextran + poly(ethylene glycol) + water aqueous two-phase system. The partition coefficients of the amino acids and peptides are aorrelated using the osmotic virial equation. The interaction coefficients contained in the equation can be calculated by hydrophilic group parameters. The partition coefficients of [alpha]-amylase calculated by the osmotic virial equation with the hydrophilic group parameters are in fairly good agreement with the experimental data, though a relatively large discrepancy is shown for [beta]-amylase. (author)

  3. Partition Coefficients of Amino Acids, Peptides, and Enzymes in Dextran + Poly(Ethylene Glycol) + Water Aqueous Two-Phase Systems

    Kakisaka, Keijiro.; Shindo, Takashi.; Iwai, Yoshio.; Arai, Yasuhiko. [Kyushu University, Fukuoka (Japan). Department of Chemical Systems and Engineering


    Partition coefficients are measured for five amino acids(aspartic acid, asparagine, methionine, cysteine and histidine) and tow peptides(glycyl-glycine and hexa-glycine) in dextran + poly(ethylene glycol) + water aqueous two-phase system. The partition coefficients of the amino acids and peptides are aorrelated using the osmotic virial equation. The interaction coefficients contained in the equation can be calculated by hydrophilic group parameters. The partition coefficients of {alpha}-amylase calculated by the osmotic virial equation with the hydrophilic group parameters are in fairly good agreement with the experimental data, though a relatively large discrepancy is shown for {beta}-amylase. (author)

  4. Lipid–water partition coefficients and correlations with uptakes by algae of organic compounds

    Hung, Wei-Nung [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 30011, Taiwan (China); Chiou, Cary T., E-mail: [Department of Environmental Engineering and Sustainable Environment Research Laboratory, National Cheng Kung University, Tainan 70101, Taiwan (China); U.S. Geological Survey, Denver Federal Center, Denver, CO 80225 (United States); Lin, Tsair-Fuh, E-mail: [Department of Environmental Engineering and Sustainable Environment Research Laboratory, National Cheng Kung University, Tainan 70101, Taiwan (China)


    Graphical abstract: - Highlights: • Partition coefficients of contaminants with lipid triolein (K{sub tw}) are measured. • Measured K{sub tw} values are nearly the same as the respective K{sub ow}. • Sorption of the contaminants to a dry algal powder is similarly measured. • Algal uptake of a compound occurs primarily by partition into the algal lipid. - Abstract: In view of the scarcity of the lipid–water partition coefficients (K{sub tw}) for organic compounds, the log K{sub tw} values for many environmental contaminants were measured using ultra-pure triolein as the model lipid. Classes of compounds studied include alkyl benzenes, halogenated benzenes, short-chain chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides. In addition to log K{sub tw} determination, the uptakes of these compounds from water by a dry algal species were measured to evaluate the lipid effect on the algal uptake. The measured log K{sub tw} are closely related to their respective log K{sub ow} (octanol–water), with log K{sub ow} = 1.9 to 6.5. A significant difference is observed between the present and early measured log K{sub tw} for compounds with log K{sub ow} > ∼5, which is attributed to the presence and absence of a triolein microemulsion in water affecting the solute partitioning. The observed lipid-normalized algae–water distribution coefficients (log K{sub aw/lipid}) are virtually identical to the respective log K{sub tw} values, which manifests the dominant lipid-partition effect of the compounds with algae.

  5. Determining Partition Coefficient (Log P), Distribution Coefficient (Log D) and Ionization Constant (pKa) in Early Drug Discovery.

    Bharate, Sonali S; Kumar, Vikas; Vishwakarma, Ram A


    An early prediction of physicochemical properties is highly desirable during drug discovery to find out a viable lead candidate. Although there are several methods available to determine partition coefficient (log P), distribution coefficient (log D) and ionization constant (pKa), none of them involves simple and fixed, miniaturized protocols for diverse set of compounds. Therefore, it is necessary to establish simple, uniform and medium-throughput protocols requiring small sample quantities for the determination of these physicochemical properties. Log P and log D were determined by shake flask method, wherein, the compound was partitioned between presaturated noctanol and water phase (water/PBS pH 7.4) and the concentration of compound in each phase was determined by HPLC. The pKa determination made use of UV spectrophotometric analysis in a 96-well microtiter plate containing a series of aqueous buffers ranging from pH 1.0 to 13.0. The medium-throughput miniaturized protocols described herein, for determination of log P, log D and pKa, are straightforward to set up and require very small quantities of sample (< 5 mg for all three properties). All established protocols were validated using diverse set of compounds.

  6. Partition coefficients for the SAMPL5 challenge using transfer free energies

    Jones, Michael R.; Brooks, Bernard R.; Wilson, Angela K.


    SAMPL challenges (Mobley et al. in J Comput Aided Mol Des 28:135-150, 2014; Skillman in J Comput Aided Mol Des 26:473-474, 2012; Geballe in J Comput Aided Mol Des 24:259-279, 2010; Guthrie in J Phys Chem B 113:4501-4507, 2009) provide excellent opportunities to assess theoretical approaches on new data sets with a goal of gaining greater insight towards protein and ligand modeling. In the SAMPL5 experiment, cyclohexane-water partition coefficients were determined using a vertical solvation scheme in conjunction with the SMD continuum solvent model. Several DFT functionals partnered with correlation consistent basis sets were evaluated for the prediction of the partition coefficients. The approach chosen for the competition, a B3PW91 vertical solvation scheme, yields a mean absolute deviation of 1.9 logP units and performs well at estimating the correct hydrophilicity and hydrophobicity for the full SAMPL5 molecule set.

  7. Prediction of air to liver partition coefficient for volatile organic compounds using QSAR approaches.

    Dashtbozorgi, Zahra; Golmohammadi, Hassan


    In this work a quantitative structure-activity relationship (QSAR) technique was developed to investigate the air to liver partition coefficient (log Kliver) for volatile organic compounds (VOCs). Suitable set of molecular descriptors was calculated and the important descriptors were selected by GA-PLS methods. These variables were served as inputs to generate neural networks. After optimization and training of the networks, they were used for the calculation of log Kliver for the validation set. The root mean square errors for the neural network calculated log Kliver of training, test, and validation sets are 0.100, 0.091, and 0.112, respectively. Results obtained reveal the reliability and good predictivity of neural network for the prediction of air to liver partition coefficient for volatile organic compounds.

  8. Determinations of gas-liquid partition coefficients using capillary chromatographic columns. Alkanols in squalane.

    Tascon, Marcos; Romero, Lílian M; Acquaviva, Agustín; Keunchkarian, Sonia; Castells, Cecilia


    This study focused on an investigation into the experimental quantities inherent in the determination of partition coefficients from gas-liquid chromatographic measurements through the use of capillary columns. We prepared several squalane - (2,6,10,15,19,23-hexamethyltetracosane) - containing columns with very precisely known phase ratios and determined solute retention and hold-up times at 30, 40, 50 and 60°C. We calculated infinite dilution partition coefficients from the slopes of the linear regression of retention factors as a function of the reciprocal of the phase ratio by means of fundamental chromatographic equations. In order to minimize gas-solid and liquid-solid interface contributions to retention, the surface of the capillary inner wall was pretreated to guarantee a uniform coat of stationary phase. The validity of the proposed approach was first tested by estimating the partition coefficients of n-alkanes between n-pentane and n-nonane, for which compounds data from the literature were available. Then partition coefficients of sixteen aliphatic alcohols in squalane were determined at those four temperatures. We deliberately chose these highly challenging systems: alcohols in the reference paraffinic stationary phase. These solutes exhibited adsorption in the gas-liquid interface that contributed to retention. The corresponding adsorption constant values were estimated. We fully discuss here the uncertainties associated with each experimental measurement and how these fundamental determinations can be performed precisely by circumventing the main drawbacks. The proposed strategy is reliable and much simpler than the classical chromatographic method employing packed columns.

  9. An alternative approach for the use of water solubility of nonionic pesticides in the modeling of the soil sorption coefficients.

    dos Reis, Ralpho Rinaldo; Sampaio, Silvio César; de Melo, Eduardo Borges


    The collection of data to study the damage caused by pesticides to the environment and its ecosystems is slowly acquired and costly. Large incentives have been established to encourage research projects aimed at building mathematical models for predicting physical, chemical or biological properties of environmental interest. The organic carbon normalized soil sorption coefficient (K(oc)) is an important physicochemical property used in environmental risk assessments for compounds released into the environment. Many models for predicting logK(oc) that have used the parameters logP or logS as descriptors have been published in recent decades. The strong correlation between these properties (logP and logS) prevents them from being used together in multiple linear regressions. Because the sorption of a chemical compound in soil depends on both its water solubility and its water/organic matter partitioning, we assume that models capable of combining these two properties can generate more realistic results. Therefore, the objective of this study was to propose an alternative approach for modeling logK(oc), using a simple descriptor of solubility, here designated as the logarithm of solubility corrected by octanol/water partitioning (logS(P)). Thus, different models were built with this descriptor and with the conventional descriptors logP and logS, alone or associated with other explanatory variables representing easy-to-interpret physicochemical properties. The obtained models were validated according to current recommendations in the literature, and they were compared with other previously published models. The results showed that the use of logS(p) instead of conventional descriptors led to simple models with greater statistical quality and predictive power than other more complex models found in the literature. Therefore, logS(P) can be a good alternative to consider for the modeling of logK(oc) and other properties that relate to both solubility and water

  10. Estimation of the soil-water partition coefficient normalized to organic carbon for ionizable organic chemicals

    Franco, Antonio; Trapp, Stefan


    The sorption of organic electrolytes to soil was investigated. A dataset consisting of 164 electrolytes, composed of 93 acids, 65 bases, and six amphoters, was collected from literature and databases. The partition coefficient log KOW of the neutral molecule and the dissociation constant pKa were...... calculated by the software ACD/Labs®. The Henderson-Hasselbalch equation was applied to calculate dissociation. Regressions were developed to predict separately for the neutral and the ionic molecule species the distribution coefficient (Kd) normalized to organic carbon (KOC) from log KOW and pKa. The log...

  11. Partition coefficient of cadmium between organic soils and bean and oat plants

    Siddqui, M.F.R.; Courchesne, F.; Kennedy, G.; Zayed, J. [Univ. de Montreal, Quebec (Canada)


    Environmental fate models require the partition coefficient data of contaminants among two or more environmental compartments. The bioaccumulation of cadmium (Cd) by bean and oat plants grown on organic soils in a controlled growth chamber was investigated to validate the plant/soil partition coefficient. Total Cd was measured in the soils and in the different parts of the plants. The mean total Cd concentrations for soil cultivated with beans and oats were 0.86 and 0.69 {micro}g/g, respectively. Selective extractants (BaCl{sub 2}, Na-pyrophosphate and HNO{sub 3}-hydroxy) were used to evaluate solid phase Cd species in the soil. In the soil cultivated with bean, BaCl{sub 2} exchangeable, Na-pyrophosphate extractable and HNO{sub 3}-NH{sub 2}OH extractable Cd represented 1.2, 1.6 and 50.9% of total soil Cd, respectively. For the soil cultivated with oats, the same extractants gave values of 1.1, 1.8 and 61.9%. Cd concentration levels in bean plants followed the sequence roots > fruits = stems > leaves (p < 0.01) while the following sequence was observed for oat plants: roots > fruits > stems > leaves (p < 0.05). The partition coefficient for total Cd (Cd{sub Plant tissue}/Cd{sub Soil}) was in the range of 0.28--0.55 for bean plants and 1.03--1.86 for oat plants.

  12. Hf, Zr, and REE partition coefficients between ilmenite and liquid - Implications for lunar petrogenesis

    Nakamura, Y.; Fujimaki, H.; Nakamura, N.; Tatsumoto, M.; Mckay, G. A.


    Partition coefficients (D) between ilmenite and coexisting liquid were determined under near-lunar conditions for Hf, Zr, and REE. Through isotope dilution analysis, ilmenite D values of 0.41 and 0.33 were obtained for Hf and Zr respectively, values significantly lower than those of ilmenite from a kimberlite megacryst. Partition coefficients of REE for the synthesized ilmenite are slightly smaller than those of ilmenite from the kimberlite megacryst, and the lunar (Lu) partition coefficient is 0.056. These results suggest that ilmenite was significant in the lunar-Hf evolution of lunar mare basalts. Using lunar and Hf D values for ilmenite, the Lu-Hf evolution of lunar cumulates and the coexisting magma was examined for various crystallization sequences. The Lu-Hf variation trend of most high-Ti mare basalts is explained by a small degree of partial cumulate melting, though a higher degree is required to explain the variation of very low-Ti basalts, green glass, and Apollo 12 low-Ti basalts. Apollo 15 low-Ti basalts may require chromite crystallization as well.

  13. REE Partition Coefficients from Synthetic Diogenite-Like Enstatite and the Implications of Petrogenetic Modeling

    Schwandt, C. S.; McKay, G. A.


    Determining the petrogenesis of eucrites (basaltic achondrites) and diogenites (orthopyroxenites) and the possible links between the meteorite types was initiated 30 years ago by Mason. Since then, most investigators have worked on this question. A few contrasting theories have emerged, with the important distinction being whether or not there is a direct genetic link between eucrites and diogenites. One theory suggests that diogenites are cumulates resulting from the fractional crystallization of a parent magma with the eucrites crystallizing, from the residual magma after separation from the diogenite cumulates. Another model proposes that diogenites are cumulates formed from partial melts derived from a source region depleted by the prior generation of eucrite melts. It has also been proposed that the diogenites may not be directly linked to the eucrites and that they are cumulates derived from melts that are more orthopyroxene normative than the eucrites. This last theory has recently received more analytical and experimental support. One of the difficulties with petrogenetic modeling is that it requires appropriate partition coefficients for modeling because they are dependent on temperature, pressure, and composition. For this reason, we set out to determine minor- and trace-element partition coefficients for diogenite-like orthopyroxene. We have accomplished this task and now have enstatite/melt partition coefficients for Al, Cr, Ti, La, Ce, Nd, Sm, Eu, Dy, Er, Yb, and La.

  14. Development of a model to predict partition coefficient of organic pollutants in cloud point extraction process.

    Shahmirani, Samareh; Farahani, Ebrahim Vasheghani; Ghasemi, Jahanbakhsh


    A quantitative structure property relationship (QSPR) study has been performed to establish a model to relate structural descriptors of 45 organic compounds to their partition coefficients in water-hexadecylpyridinium chloride (CPC) micelles at 298K using partial least squares (PLS). 510 of six different categories of structural descriptors were calculated by Dragon software. The descriptors with 0.9 mutually pair correlations and with less than 0.1 with dependent variables were excluded at the early stage of the preprocessing of the structural data matrix. The data set was randomly divided into two groups: training set (40 molecules) and test set (5 molecules). In the final model 50 of the most effective of the structural descriptors on the partition coefficient were remained to model building by PLS calibration method. The optimum number of latent variables 5, which spanned 80% of the original variations of data matrix, was selected using leave one out cross validation method. Prediction ability of the model was tested by prediction of the partition coefficients of five unknown compounds and the mean relative error of prediction was 3.6%. The outliers were treated using leverage and score plots of the first third principal components. The efficiency of the new model was compared with Abraham model and it was found that the proposed model has more prediction ability.

  15. Simultaneous Description of Activity Coefficients and Solubility with eCPA

    Schlaikjer, Anders; Thomsen, Kaj; Kontogeorgis, Georgios


    with salt specific parameters. The focus is on accurate description of the salt solubility, and low deviation correlations are obtained for all salts investigated. The inclusion of the solubility data in the parametrization has, compared to parameters only parametrized to osmotic coefficients and activity...... coefficients, not significantly affected the deviations of the osmotic coefficients and activity coefficients. The average deviations of the activity coefficient does increase slightly and it was found that the increase in deviations was almost entirely due to reduced accuracy at high temperature and high...... molality. The model is, furthermore, compared to the activity coefficient model, Extended UNIQUAC. It is shown that the eCPA provides more accurate solubility description at higher temperatures than Extended UNIQUAC but also that Extended UNIQUAC is slightly better at describing the activity coefficients...

  16. Determination of the subcooled liquid solubilities of PAHs in partitioning batch experiments

    Lihua Liu


    Full Text Available Subcooled liquid solubility is the water solubility for a hypothetical state of liquid. It is an important parameter for multicomponent nonaqueous phase liquids (NAPLs containing polycyclic aromatic hydrocarbons (PAHs, which can exist as liquids even though most of the solutes are solid in their pure form at ambient temperature. So far, subcooled liquid solubilities were estimated from the solid water solubility and fugacity ratio of the solid and (subcooled liquid phase, but rarely derived from experimental data. In our study, partitioning batch experiments were performed to determine the subcooled liquid solubility of PAHs in NAPL-water system. For selected PAH, a series of batch experiments were carried out at increased mole fractions of the target component in the NAPL and at a constant NAPL/water volume ratio. The equilibrium aqueous PAH concentrations were measured with HPLC and/or GC-MS. The subcooled liquid solubility was derived by extrapolation of the experimental equilibrium aqueous concentration to a mole fraction of unity. With the derived subcooled liquid solubility, the fugacity ratio and enthalpy of fusion of the solute were also estimated. Our results show a good agreement between the experimentally determined and published data.

  17. Limiting activity coefficients and gas-liquid partition coefficients of various solutes in piperidinium ionic liquids: measurements and LSER calculations.

    Paduszyński, Kamil; Domańska, Urszula


    This paper is a continuation of our systematic investigations on piperidinium ionic liquids and presents new data on activity coefficients at infinite dilution for 43 solutes: linear and branched alkanes, cycloalkanes, alkenes, alkynes, benzene, alkylbenzenes, alcohols, water, thiophene, tetrahyrdofuran (THF), methyl tert-butyl ether (MTBE), linear ethers, acetone, and linear ketones in the ionic liquid 1-butyl-1-methyl-piperidinium bis(trifluoromethylsulfonyl)imide, [BMPIP][NTf2]. The data were determined by gas-liquid chromatography (GLC) at temperatures from 308.15 to 358.15 K. These values were compared to those previously published for the bis-(trifluoromethylsulfonyl)imide-based ionic liquids. The partial molar excess enthalpies ΔH1(E,∞) and entropies ΔS1(E,∞) at infinite dilution were calculated from the experimental γ13(∞) values obtained over the temperature range. The values of the selectivities for different separation problems were calculated from γ13(∞) and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and additional ionic liquids. Experimental limiting activity coefficients were used to calculate gas-IL partition coefficients of solutes, K(L). The modeling with specific linear solvation energy relationship (LSER) equations was performed for data obtained in this work and those reported earlier for 1-butyl-1-methylpiperidinium thiocyanate, [BMPIP][SCN].

  18. Measurement and Correlation of Partition Coefficients of Baicalin in EOPO/Salt Aqueous Two-Phase Systems

    李伟; 朱自强


    The partition coefficients of baicalin were measured in ethylene oxide and propylene oxide(EOPO)/salt aqueous two-phase systems at 298.15K,It was found that most of baicalin partitioned into EOPO-rich phase.The partition coefficients of baicalin varied from 10 to 120.The effect of various factors,including tie-line lngth,salt composition,molecular weight of EOPO,and solution pH,on the partition behavior was investigated on EOPO/salt systems.Furthermore the partition coefficients of baicalin were correlated using the modified Diamond-Hsu model.Good agreement with experimental data is obtained.The average relative deviations are less than 5.0%.

  19. Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments

    Schwandt, Craig S.; McKay, Gordon A.


    Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were measured in both the basaltic glass and the enstatite. Rare earth element concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare earth element concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare earth element partition signature for enstatite is similar to previous calculated and composite low-Ca pigeonite signatures, but is better defined and differs in several details. The partition coefficients are consistent with crystal structural constraints.

  20. Development of a model to determine mass transfer coefficient and oxygen solubility in bioreactors

    Johnny Lee


    where T is in degree Kelvin, and the subscripts refer to degree Celsius; E, ρ, σ are properties of water. Furthermore, using data from published data on oxygen solubility in water, it was found that solubility bears a linear and inverse relationship with the mass transfer coefficient.

  1. Setup and validation of shake-flask procedures for the determination of partition coefficients (logD) from low drug amounts.

    Andrés, Axel; Rosés, Martí; Ràfols, Clara; Bosch, Elisabeth; Espinosa, Sonia; Segarra, Víctor; Huerta, Josep M


    Several procedures based on the shake-flask method and designed to require a minimum amount of drug for octanol-water partition coefficient determination have been established and developed. The procedures have been validated by a 28 substance set with a lipophilicity range from -2.0 to 4.5 (logD7.4). The experimental partition is carried out using aqueous phases buffered with phosphate (pH 7.4) and n-octanol saturated with buffered water and the analysis is performed by liquid chromatography. In order to have accurate results, four procedures and eight different ratios between phase volumes are proposed. Each procedure has been designed and optimized (for partition ratios) for a specific range of drug lipophilicity (low, regular and high lipophilicity) and solubility (high and low aqueous solubility). The procedures have been developed to minimize the measurement in the octanolic phase. Experimental logD7.4 values obtained from different procedures and partition ratios show a standard deviation lower than 0.3 and there is a nice agreement when these values are compared with the reference literature ones.

  2. Determination of partition and diffusion coefficient of formaldehyde in selected building materials and impact of relative humidity

    The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, "green" gypsum wallboard, and "green" carpet) under three relative humidity (RH) conditions (20%, 50% and 70% RH). A dynamic dual-chamber test meth...

  3. Determination of partition and diffusion coefficients of formaldehyde in selected building materials and impact of relative humidity (journal)

    The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, "green" gypsum wallboard, and "green" carpet) under three relative humidity (RH) conditions (20%, 50% and 70% RH). A dynamic dual-chamber test meth...

  4. Determination of the tissue-to-blood partition coefficient for 131iodo-antipyrine in human subcutaneous adipose tissue

    Jelnes, R; Astrup, A


    131Iodo-antipyrine (131I-AP) is commonly used for blood flow measurements in adipose tissue. These estimations have been based on the assumption of the tissue-to-blood partition coefficient being 1 ml g-1. No exact determination of the tissue-to-blood partition coefficient for 131I-AP in adipose...... tissue has been carried out. In the present study a partition coefficient of 1.12 +/- 0.06 (mean +/- S.D.) for 131I-AP in adipose tissue has been determined based on the partition coefficient for 131I-AP between lipid-saline (1.24 ml g-1), red blood cells-plasma (0.64 ml g-1), protein-saline (0.19 ml g-1...

  5. Prediction of water-phosphatidylcholine membrane partition coefficient of some drugs from their molecular structures.

    Fatemi, Mohammad Hossein; Moghaddam, Masoomeh Raei


    In this work, the phosphatidylcholine membrane-water partition coefficients (MA) of some drugs were estimated from their theoretical derived molecular descriptors by applying quantitative structure-activity relationship (QSAR) methodology. The data set consisted of 46 drugs where their log MA were determined experimentally. Descriptors used in this work were calculated by DRAGON (version 1) package, on the basis of optimized molecular structures, and the most relevant descriptors were selected by stepwise multilinear regressions (MLRs). These descriptors were used to developing linear and nonlinear models by using MLR and artificial neural networks (ANNs), respectively. During this investigation, the best QSAR model was identified when using the ANN model that produced a reasonable level of correlation coefficients (R(train) = 0.995, R(test) = 0.948) and low standard error (SE(train) = 0.099, SE(test) = 0.326). The built model was fully assessed by various validation methods, including internal and external validation test, Y-randomization test, and cross-validation (Q(2) = 0.805). The results of this investigation revealed the applicability of QSAR approaches in the estimation of phosphatidylcholine membrane-water partition coefficients.

  6. Application of radial basis function neural network to predict soil sorption partition coefficient using topological descriptors.

    Sabour, Mohammad Reza; Moftakhari Anasori Movahed, Saman


    The soil sorption partition coefficient logKoc is an indispensable parameter that can be used in assessing the environmental risk of organic chemicals. In order to predict soil sorption partition coefficient for different and even unknown compounds in a fast and accurate manner, a radial basis function neural network (RBFNN) model was developed. Eight topological descriptors of 800 organic compounds were used as inputs of the model. These 800 organic compounds were chosen from a large and very diverse data set. Generalized Regression Neural Network (GRNN) was utilized as the function in this neural network model due to its capability to adapt very quickly. Hence, it can be used to predict logKoc for new chemicals, as well. Out of total data set, 560 organic compounds were used for training and 240 to test efficiency of the model. The obtained results indicate that the model performance is very well. The correlation coefficients (R2) for training and test sets were 0.995 and 0.933, respectively. The root-mean square errors (RMSE) were 0.2321 for training set and 0.413 for test set. As the results for both training and test set are extremely satisfactory, the proposed neural network model can be employed not only to predict logKoc of known compounds, but also to be adaptive for prediction of this value precisely for new products that enter the market each year. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Simultaneous Rapid Determination of the Solubility and Diffusion Coefficients of a Poorly Water-Soluble Drug Based on a Novel UV Imaging System.

    Lu, Yan; Li, Mingzhong


    The solubility and diffusion coefficient are two of the most important physicochemical properties of a drug compound. In practice, both have been measured separately, which is time consuming. This work utilizes a novel technique of UV imaging to determine the solubility and diffusion coefficients of poorly water-soluble drugs simultaneously. A 2-step optimal method is proposed to determine the solubility and diffusion coefficients of a poorly water-soluble pharmaceutical substance based on the Fick's second law of diffusion and UV imaging measurements. Experimental results demonstrate that the proposed method can be used to determine the solubility and diffusion coefficients of a drug with reasonable accuracy, indicating that UV imaging may provide a new opportunity to accurately measure the solubility and diffusion coefficients of a poorly water-soluble drug simultaneously and rapidly. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  8. Developing QSPR model of gas/particle partition coefficients of neutral poly-/perfluoroalkyl substances

    Yuan, Quan; Ma, Guangcai; Xu, Ting; Serge, Bakire; Yu, Haiying; Chen, Jianrong; Lin, Hongjun


    Poly-/perfluoroalkyl substances (PFASs) are a class of synthetic fluorinated organic substances that raise increasing concern because of their environmental persistence, bioaccumulation and widespread presence in various environment media and organisms. PFASs can be released into the atmosphere through both direct and indirect sources, and the gas/particle partition coefficient (KP) is an important parameter that helps us to understand their atmospheric behavior. In this study, we developed a temperature-dependent predictive model for log KP of PFASs and analyzed the molecular mechanism that governs their partitioning equilibrium between gas phase and particle phase. All theoretical computation was carried out at B3LYP/6-31G (d, p) level based on neutral molecular structures by Gaussian 09 program package. The regression model has a good statistical performance and robustness. The application domain has also been defined according to OECD guidance. The mechanism analysis shows that electrostatic interaction and dispersion interaction play the most important role in the partitioning equilibrium. The developed model can be used to predict log KP values of neutral fluorotelomer alcohols and perfluor sulfonamides/sulfonamidoethanols with different substitutions at nitrogen atoms, providing basic data for their ecological risk assessment.

  9. Experimental Determination of Trace Element Partition Coefficients Between Zircon, Garnet and Melt

    Taylor, R. J.; Harley, S. L.; Hinton, R. W.; Elphick, S.


    The problem of relating ages, as calculated by zircon U-Pb geochronology, to processes and hence geoological events is central to understanding mountain building and crustal evolution. Accurate P-T-t paths can only be produced if zircon growth can be linked to specific rock and mineral processes used to establish pressure and temperature values for metamorphic episodes. As a major metamorphic mineral in crustal events, garnet is widely used as a thermobarometric tool, and linking garnet growth to zircon formation could be used to refine the interpretation of U-Pb ages. Attempts to resolve this issue have focussed on REE partitioning between zircon and garnet, both of which strongly incorporate the HREE into their structure, and so it is possible there is a distinct REE partitioning signature which will highlight whether the two minerals have grown in equilibrium. There are two complementary methods to obtaining this information, empirical and experimental. Empirical methods of determining this signature using carefully selected rocks have proved troublesome, with a wide range of partitioning signatures found. This work has used experimental techniques to produce zircon-melt, garnet-melt and zircon-garnet-melt partition coefficients at a range of P-T conditions using synthetic materials. Zircon and garnet are grown in trace element equilibrium with a water-undersaturated granitic melt, which represents partial melts formed in the lower crust during anatexis. Temperature ranges from 850°C to 1000°C at a pressure of 5Kbar were produced using internally heated gas apparatus. Trace element concentrations were measured using SIMS analysis at the Ion Microprobe Facility at the University of Edinburgh. The experimental data produced will be applied to interpret chemical signatures in zircon in garnet-bearing metamorphic rocks, and will provide an objective basis for interpretation of the timing of growth or recrystallisation of zircon in many high-grade terrains.

  10. Development of a full automation solid phase microextraction method for investigating the partition coefficient of organic pollutant in complex sample.

    Jiang, Ruifen; Lin, Wei; Wen, Sijia; Zhu, Fang; Luan, Tiangang; Ouyang, Gangfeng


    A fully automated solid phase microextraction (SPME) depletion method was developed to study the partition coefficient of organic compound between complex matrix and water sample. The SPME depletion process was conducted by pre-loading the fiber with a specific amount of organic compounds from a proposed standard gas generation vial, and then desorbing the fiber into the targeted samples. Based on the proposed method, the partition coefficients (Kmatrix) of 4 polyaromatic hydrocarbons (PAHs) between humic acid (HA)/hydroxypropyl-β-cyclodextrin (β-HPCD) and aqueous sample were determined. The results showed that the logKmatrix of 4 PAHs with HA and β-HPCD ranged from 3.19 to 4.08, and 2.45 to 3.15, respectively. In addition, the logKmatrix values decreased about 0.12-0.27 log units for different PAHs for every 10°C increase in temperature. The effect of temperature on the partition coefficient followed van't Hoff plot, and the partition coefficient at any temperature can be predicted based on the plot. Furthermore, the proposed method was applied for the real biological fluid analysis. The partition coefficients of 6 PAHs between the complex matrices in the fetal bovine serum and water were determined, and compared to ones obtained from SPME extraction method. The result demonstrated that the proposed method can be applied to determine the sorption coefficients of hydrophobic compounds between complex matrix and water in a variety of samples.

  11. Determination of octanol-water partition coefficients of polar polycyclic aromatic compounds (N-PAC) by high performance liquid chromatography

    Helweg, C.; Nielsen, T.; Hansen, P.E.


    Prediction of 1-octanol water partition coefficients for a range of polar N-PAC from HPLC capacity coefficients has been investigated. Two commercially available columns, an ODS column and a Diol column were tested with water-methanol eluents. The best prediction of log K-ow for N-PAC was achieve...

  12. Correlation and prediction of partition coefficient using nonrandom two-liquid segment activity coefficient model for solvent system selection in counter-current chromatography separation.

    Ren, Da-Bing; Yang, Zhao-Hui; Liang, Yi-Zeng; Ding, Qiong; Chen, Chen; Ouyang, Mei-Lan


    Selection of a suitable solvent system is the first and foremost step for a successful counter-current chromatography (CCC) separation. In this paper, a thermodynamic model, nonrandom two-liquid segment activity coefficient model (NRTL-SAC) which uses four types of conceptual segments to describe the effective surface interactions for each solvent and solute molecule, was employed to correlate and predict the partition coefficients (K) of a given compound in a specific solvent system. Then a suitable solvent system was selected according to the predicted partition coefficients. Three solvent system families, heptane/methanol/water, heptane/ethyl acetate/methanol/water (Arizona) and hexane/ethyl acetate/methanol/water, and several solutes were selected to investigate the effectiveness of the NRTL-SAC model for predicting the partition coefficients. Comparison between experimental results and predicted results showed that the NRTL-SAC model is of potential for estimating the K value of a given compound. Also a practical separation case on magnolol and honokiol suggests the NRTL-SAC model is effective, reliable and practical for the purpose of predicting partition coefficients and selecting a suitable solvent system for CCC separation. Copyright © 2013. Published by Elsevier B.V.

  13. Determination of Teicoplanin A2's Partition Coefficient in Different Liquid-Liquid Extraction Systems%替考拉宁在不同液液萃取体系中分配系数的测定

    陈勇; Bin Mat Hanapi; 徐志南; 金志华; 岑沛霖


    Teicoplanin is one of the macrocyclic glycopeptide antibiotics, which is active against Gram-positive bacteria, and has attracted a lot of attention in the field of chiral separation recently. In this work, the partition coefficients and extraction ratio of teicoplanin in three different solvent systems were studied: conventional extraction,reactive extraction and reverse micelle extraction. With conventional solvent extraction, n-butanol demonstrated high partition coefficient for teicoplanin, but low extraction ratio because of its high solubility in water. Reactive extraction of teicoplanin showed the highest partition coefficient with almost 100% recovery in organic phase when tri-n-octylmethyl ammonium chloride (TOMAC) was used as extractant and pH value was above 5.0. A reverse for teicoplanin. The results are beneficial for the design of teicoplanin separation and purification process.

  14. Predictive relationships for the effects of triglyceride ester concentration and water uptake on solubility and partitioning of small molecules into lipid vehicles.

    Cao, Yichen; Marra, Michelle; Anderson, Bradley D


    The ability to predict drug solubility and partitioning in triglyceride solvents from the chemical structures of the solute and the triglyceride would be highly useful in drug formulation development and in screening drug candidates for lipid solubility and possibly drug bioavailability. This study explores the role of triglyceride ester concentration on small molecule partitioning between lipid vehicles and water, including the effect of ester concentration on water uptake. The influence of solvated water is further examined in studies of small molecule solubility in dry and water saturated lipid vehicles varying in triglyceride ester concentration. A series of model solutes with varying hydrogen bond donating/accepting abilities was chosen for this study while triglyceride ester concentrations were varied by using squalane/tricaprylin solvent mixtures. General linear free energy solvation relationships having the form utilized previously by Abraham were obtained at each solvent composition. An examination of the solvent descriptors indicated that those descriptors representing the sensitivity of the solvent to the solute dipolarity/polarizability, s, and to the hydrogen bond acidity of the solute, a, vary systematically with the concentration of ester moieties in the solvent mixture. An empirical equation has been derived that offers the potential for predicting triglyceride/water partition coefficients and in certain cases, solubility in hydrated, fully-saturated triglyceride solvents for any small molecule for which Abraham solute descriptors can be obtained. Water uptake in triglyceride vehicles is shown to be approximately linear with water activity and may also be described by the empirical relationship developed for other solutes providing an adjustment is made in the value of its hydrogen bond acidity parameter. Water uptake enhances the solubility of benzamide and N-methylbenzamide and a modest "water-dragging" effect by N-methylbenzamide in the

  15. Octanol-Water Partition Coefficient from 3D-RISM-KH Molecular Theory of Solvation with Partial Molar Volume Correction.

    Huang, WenJuan; Blinov, Nikolay; Kovalenko, Andriy


    The octanol-water partition coefficient is an important physical-chemical characteristic widely used to describe hydrophobic/hydrophilic properties of chemical compounds. The partition coefficient is related to the transfer free energy of a compound from water to octanol. Here, we introduce a new protocol for prediction of the partition coefficient based on the statistical-mechanical, 3D-RISM-KH molecular theory of solvation. It was shown recently that with the compound-solvent correlation functions obtained from the 3D-RISM-KH molecular theory of solvation, the free energy functional supplemented with the correction linearly related to the partial molar volume obtained from the Kirkwood-Buff/3D-RISM theory, also called the "universal correction" (UC), provides accurate prediction of the hydration free energy of small compounds, compared to explicit solvent molecular dynamics [ Palmer , D. S. ; J. Phys.: Condens. Matter 2010 , 22 , 492101 ]. Here we report that with the UC reparametrized accordingly this theory also provides an excellent agreement with the experimental data for the solvation free energy in nonpolar solvent (1-octanol) and so accurately predicts the octanol-water partition coefficient. The performance of the Kovalenko-Hirata (KH) and Gaussian fluctuation (GF) functionals of the solvation free energy, with and without UC, is tested on a large library of small compounds with diverse functional groups. The best agreement with the experimental data for octanol-water partition coefficients is obtained with the KH-UC solvation free energy functional.


    Yerramsetty, Krishna M; Neely, Brian J; Gasem, Khaled A M


    Octanol-water partition coefficient (K(ow)) is an important thermodynamic property used to characterize the partitioning of solutes between an aqueous and organic phase and has importance in such areas as pharmacology, pharmacokinetics, pharmacodynamics, chemical production and environmental toxicology. We present a non-linear quantitative structure-property relationship model for determining K(ow) values of new molecules in silico. A total of 823 descriptors were generated for 11,308 molecules whose K(ow) values are reported in the PhysProp dataset by Syracuse Research. Optimum network architecture and its associated inputs were identified using a wrapper-based feature selection algorithm that combines differential evolution and artificial neural networks. A network architecture of 50-33-35-1 resulted in the least root-mean squared error (RMSE) in the training set. Further, to improve on single-network predictions, a neural network ensemble was developed by combining five networks that have the same architecture and inputs but differ in layer weights. The ensemble predicted the K(ow) values with RMSE of 0.28 and 0.38 for the training set and internal validation set, respectively. The ensemble performed reasonably well on an external dataset when compared with other popular K(ow) models in the literature.

  17. Rapid determination of octanol-water partition coefficient using vortex-assisted liquid-liquid microextraction.

    Román, Iván P; Mastromichali, Anna; Tyrovola, Konstantina; Canals, Antonio; Psillakis, Elefteria


    Vortex-assisted liquid-liquid microextraction (VALLME) coupled with high-performance liquid chromatography (HPLC) is proposed here for the rapid determination of octanol-water partitioning coefficients (Kow). VALLME uses vortex agitation, a mild emulsification procedure, to disperse microvolumes of octanol in the aqueous phase thus increasing the interfacial contact area and ensuring faster partitioning rates. With VALLME, 2min were enough to achieve equilibrium conditions between the octanolic and aqueous phases. Upon equilibration, separation was achieved using centrifugation and the octanolic microdrop was collected and analyzed in a HPLC system. Six model compounds with logKow values ranging between ∼0.5 and 3.5 were used during the present investigations. The proposed method produced logKow values that were consistent with previously published values and the recorded uncertainty was well within the acceptable log unit range. Overall, the key features of the proposed Kow determination procedure comprised speed, reliability, simplicity, low cost and minimal solvent consumption.

  18. Determination of nitrogen partitioning coefficients in superduplex stainless steels by NRA using a nuclear microprobe

    Munoz, C. [Centro Nacional de Aceleradores, Av. Thomas A. Edison 7, Isla de La Cartuja, E-41092 Sevilla (Spain)], E-mail:; Morilla, Y.; Garcia Lopez, J. [Centro Nacional de Aceleradores, Av. Thomas A. Edison 7, Isla de La Cartuja, E-41092 Sevilla (Spain); Paul, A. [Departamento de Ingenieria Mecanica y de los Materiales ESI, Universidad de Sevilla, E-41092 Sevilla, Av. de los Descubrimientos s/n (Spain); Odriozola, J.A. [Departamento de Quimica Inorganica e Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla - CSIC, E-41092 Sevilla, Av. Americo Vespucio 49 (Spain)


    Superduplex stainless steels (SDSSs) combine the good mechanical behavior and the high corrosion resistance of the ferrite ({alpha}-Fe) and austenite ({gamma}-Fe) phases. The SDSSs properties depend strongly on the partitioning of the elements that form the alloy. The ferrite is generally enriched in P, Si, Cr and Mo while the content of Ni, Mn, Cu and N in the austenite phase is higher. Nitrogen is known to be a strong austenite stabilizer and its presence increases the strength and the pitting corrosion resistance of the stainless steels. While the global nitrogen content in SDSSs can be readily determined using elemental analyzers, it cannot be measured at a microscopic scale. In this work, the nuclear microprobe of the Centro Nacional de Aceleradores (Sevilla) was used to obtain the quantitative distribution of nitrogen in SDSSs. A deuteron beam of 1.8 MeV was employed to determine the overall elemental concentration of the matrix by deuteron-induced X-ray emission, whereas the nitrogen partitioning coefficients were obtained by using the {sup 14}N(d, {alpha}{sub 0}){sup 12}C nuclear reaction. Mappings of this element show that the nitrogen ratio between the ferrite and austenite phases ranges from 0.3 to 0.6 in the analyzed samples.

  19. Tissue/blood partition coefficients for xenon in various adipose tissue depots in man

    Bülow, J; Jelnes, Rolf; Astrup, A


    Tissue/blood partition coefficients (lambda) for xenon were calculated for subcutaneous adipose tissue from the abdominal wall and the thigh, and for the perirenal adipose tissue after chemical analysis of the tissues for lipid, water and protein content. The lambda in the perirenal tissue...... was found to correlate linearly to the relative body weight (RBW) in per cent with the regression equation lambda = 0.045 . RBW + 0.99. The subcutaneous lambda on the abdomen correlated linearly to the local skinfold thickness (SFT) with the equation lambda = 0.22 SFT + 2.99. Similarly lambda on the thigh...... correlated to SFT with the equation lambda = 0.20 . SFT + 4.63. It is concluded that the previously accepted lambda value of 10 is generally too high in perirenal as well as in subcutaneous tissue. Thus, by application of the present regression equations, it is possible to obtain more exact estimates...

  20. QSPR Study on Octanol/water Partition Coefficient (lgKow) of Substituted Naphthalin Compounds

    ZENG Xiao-Lan; WANG Zun-Yao; ZHAI Zhi-Cai; ZHU Jin-Jin


    Structural parameters of 24 substituted naphthalin compounds were computed at four levels using Hartree-Fock and DFT methods. Based on the experimental data of octanol/water partition coefficient (lgKow), three-parameter (energy of the highest occupied molecular orbital (EHOMO), the most positive atomic net charges of molecule (q+) and molecular average polarizability (α)) dependent equations were developed using structural parameters as theoretical descriptors. Especially, lgKow dependent equation calculated at the HF/6-311G** level is more advantageous than others in view of their correlation and predictive abilities. This dependent equation was validated by variance inflation factors (VIF) and t-test methods and used to predict lgKow of eight designed compounds. Upon comparison, the predictive abilities of our work are all more advantageous than those calculated from molecular property calculator program.

  1. Mg-perovskite/silicate melt and magnesiowuestite/silicate melt partition coefficients for KLB-1 at 250 Kbars

    Drake, Michael J.; Rubie, David C.; Mcfarlane, Elisabeth A.


    The partitioning of elements amongst lower mantle phases and silicate melts is of interest in unraveling the early thermal history of the Earth. Because of the technical difficulty in carrying out such measurements, only one direct set of measurements was reported previously, and these results as well as interpretations based on them have generated controversy. Here we report what are to our knowledge only the second set of directly measured trace element partition coefficients for a natural system (KLB-1).

  2. Time-efficient myocardial contrast partition coefficient measurement from early enhancement with magnetic resonance imaging.

    Shi-Jun Zhang

    Full Text Available OBJECTIVE: Our purpose was to validate an early enhancement time point for accurately measuring the myocardial contrast partition coefficient (lambda using dynamic-equilibrium magnetic resonance imaging. MATERIALS AND METHODS: The pre- and post-contrast longitudinal relaxation rates (reciprocal of T1 of the interventricular septum (R1(m and blood pool (R1(b were obtained from fifteen healthy volunteers and three diabetic patients with hypertension using two optimized T1 mapping sequences (modified Look-Locker inversion recovery on a 3-Tesla magnetic resonance scanner. Reference lambda values were calculated as the slope of the regression line of R1(m versus R1(b at dynamic equilibrium (multi-point regression method. The simplified pre-/post-enhancement two-acquisition method (two-point method was used to calculate lambda by relating the change in R1(m and R1(b using different protocols according to the acquisition stage of the post-enhancement data point. The agreement with the referential method was tested by calculating Pearson's correlation coefficient and the intra-class correlation coefficient. RESULTS: The lambda values measured by the two-point method increased (from 0.479 ± 0.041 to 0.534 ± 0.043 over time from 6 to 45 minutes after contrast and exhibited good correlation with the reference at each time point (r ≥ 0.875, p<0.05. The intra-class correlation coefficient on absolute agreement with the reference lambda was 0.946, 0.929 and 0.922 at the 6th, 7th and 8th minutes and dropped from 0.878 to 0.403 from the 9th minute on. CONCLUSIONS: The time-efficient two-point method at 6-8 minutes after the Gd-DTPA bolus injection exhibited good agreement with the multi-point regression method and can be applied for accurate lambda measurement in normal myocardium.

  3. Enhancement of solubility and mass transfer coefficient of salicylic acid through hydrotropy



    This study deals with the effect of hydrotropes on the solubility and mass transfer coefficient of salicylic acid.The solubility and mass transfer studies were performed using the hydrotropes,i.e.,sodium acetate,sodium salicylate,citric acid,and urea at concentrations of 0~3.0 mol/L and system temperatures of 303-333 K.It was found that the solubility and mass transfer coefficient of salicylic acid increases with increase in hydrotrope concentration and also with system temperature.All hydrotropes used in this work showed an enhancement in solubility and mass transfer coefficient to difierent degrees.The maximum enhancement factor values were determined for all hydrotropes used in this study.The highest value was 28.08 for solubility studies and 10.42 for mass trailsfer studies.The performance of hydrotropes Was measured in terms of the Setschenow constant(Ks).The highest value observed was 0.696.

  4. Determination of octan-1-ol-water partition coefficients by flow-injection extraction without phase separation

    Kuban, V. (Royal Institute of Technology, Stockholm (Sweden). Department of Analytical Chemistry)


    Single-channel coaxial segments were used for the introduction of an aqueous or octan-1-ol solution of an organic substance directly into a continuous flow of the other solvent. The analytical signal was measured simultaneously on both aqueous and organic phase segments by an 'on-tube' fast-reading spectrophotometric detector (ca. 3 ms time resolution) and treated mathematically. The octan-1-ol-water phase signal ratio corresponds to the partition coefficient of the organic substances. The applicability of the method is demonstrated by the determination of partition coefficients of phenol, citric acid, acetylsalicylic acid and sodium salicylate. (author). 8 refs.; 3 figs.; 1 tab.

  5. Computational prediction of octanol-water partition coefficient based on the extended solvent-contact model.

    Kim, Taeho; Park, Hwangseo


    The logarithm of 1-octanol/water partition coefficient (LogP) is one of the most important molecular design parameters in drug discovery. Assuming that LogP can be calculated from the difference between the solvation free energy of a molecule in water and that in 1-octanol, we propose a method for predicting the molecular LogP values based on the extended solvent-contact model. To obtain the molecular solvation free energy data for the two solvents, a proper potential energy function was defined for each solvent with respect to atomic distributions and three kinds of atomic parameters. Total 205 atomic parameters were optimized with the standard genetic algorithm using the training set consisting of 139 organic molecules with varying shapes and functional groups. The LogP values estimated with the two optimized solvation free energy functions compared reasonably well with the experimental results with the associated squared correlation coefficient and root mean square error of 0.824 and 0.697, respectively. Besides the prediction accuracy, the present method has the merit in practical applications because molecular LogP values can be computed straightforwardly from the simple potential energy functions without the need to calculate various molecular descriptors. The methods for enhancing the accuracy of the present prediction model are also discussed.

  6. Prediction of aqueous solubility, vapor pressure and critical micelle concentration for aquatic partitioning of perfluorinated chemicals.

    Bhhatarai, Barun; Gramatica, Paola


    The majority of perfluorinated chemicals (PFCs) are of increasing risk to biota and environment due to their physicochemical stability, wide transport in the environment and difficulty in biodegradation. It is necessary to identify and prioritize these harmful PFCs and to characterize their physicochemical properties that govern the solubility, distribution and fate of these chemicals in an aquatic ecosystem. Therefore, available experimental data (10-35 compounds) of three important properties: aqueous solubility (AqS), vapor pressure (VP) and critical micelle concentration (CMC) on per- and polyfluorinated compounds were collected for quantitative structure-property relationship (QSPR) modeling. Simple and robust models based on theoretical molecular descriptors were developed and externally validated for predictivity. Model predictions on selected PFCs were compared with available experimental data and other published in silico predictions. The structural applicability domains (AD) of the models were verified on a bigger data set of 221 compounds. The predicted properties of the chemicals that are within the AD, are reliable, and they help to reduce the wide data gap that exists. Moreover, the predictions of AqS, VP, and CMC of most common PFCs were evaluated to understand the aquatic partitioning and to derive a relation with the available experimental data of bioconcentration factor (BCF).

  7. PCDD/F and PCB water column partitioning examination using natural organic matter and black carbon partition coefficient models.

    Howell, Nathan L; Rifai, Hanadi S


    A 9-year water dataset from the Houston Ship Channel (HSC) was analyzed to understand partitioning in polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs). Total PCBs had more mass as dissolved (74%) whereas total PCDD/Fs did not (11%). Generally, the limited number of PCDD/Fs (only 2378 substituted) explained these differences though differences in chemical behavior beyond log K ow also likely influence partitioning. The particular fractionation seen in the HSC also seemed related to a wide variation in particulate organic carbon (POC)/dissolved organic carbon (DOC) ratio (0.42-180%). Published and unaltered linear free energy and linear solvation energy relationships for DOC, POC, and particulate black carbon (BC) resulted in predictions that were at best 27% (PCB) and 25% root-mean-square error (RMSE) (PCDD/F) partition fraction compared to observed (using estimated BC/POC fractions of 10 and 25%, respectively). These results show, at least in light of the uncertainties in this data (e.g., precise fraction of BC), that a 25% accuracy in model prediction of operationally dissolved or suspended fraction for any one PCB or PCDD/F congener is the best prediction that may be expected. It is therefore recommended that site-specific data be used to calibrate most any water column-partitioning model if it is to be expected to describe what actually occurs in field conditions.

  8. Dependence of chymosin and pepsin partition coefficient with phase volume and polymer pausidispersity in polyethyleneglycol-phosphate aqueous two-phase system.

    Spelzini, Darío; Picó, Guillemo; Farruggia, Beatriz


    The influence of the phase volume ratio and polymer pausidispersity on chymosin and pepsin partition in polyethylenglycol-phosphate aqueous two-phase systems was studied. Both proteins showed a high affinity for the polyethylenglycol rich phase with a partition coefficient from 20 to 100 for chymosin and from 20 to 180 for pepsin, when the polyethyleneglycol molecular mass in the system varied between 1450 and 8000. The partition coefficient of chymosin was not affected by the volume phase ratio, while the pepsin coefficient showed a significant decrease in its partition coefficient with the increase in the top/bottom phase volume ratio.

  9. Field estimates of polyurethane foam - air partition coefficients for hexachlorobenzene, alpha-hexachlorocyclohexane and bromoanisoles.

    Bidleman, Terry F; Nygren, Olle; Tysklind, Mats


    Partition coefficients of gaseous semivolatile organic compounds (SVOCs) between polyurethane foam (PUF) and air (KPA) are needed in the estimation of sampling rates for PUF disk passive air samplers. We determined KPA in field experiments by conducting long-term (24-48 h) air sampling to saturate PUF traps and shorter runs (2-4 h) to measure air concentrations. Sampling events were done at daily mean temperatures ranging from 1.9 to 17.5 °C. Target compounds were hexachlorobenzene (HCB), alpha-hexachlorocyclohexane (α-HCH), 2,4-dibromoanisole (2,4-DiBA) and 2,4,6-tribromoanisole (2,4,6-TriBA). KPA (mL g(-1)) was calculated from quantities on the PUF traps at saturation (ng g(-1)) divided by air concentrations (ng mL(-1)). Enthalpies of PUF-to-air transfer (ΔHPA, kJ mol(-1)) were determined from the slopes of log KPA/mL g(-1) versus 1/T(K) for HCB and the bromoanisoles, KPA of α-HCH was measured only at 14.3 to 17.5 °C and ΔHPA was not determined. Experimental log KPA/mL g(-1) at 15 °C were HCB = 7.37; α-HCH = 8.08; 2,4-DiBA = 7.26 and 2,4,6-TriBA = 7.26. Experimental log KPA/mL g(-1) were compared with predictions based on an octanol-air partition coefficient (log KOA) model (Shoeib and Harner, 2002a) and a polyparameter linear free relationship (pp-LFER) model (Kamprad and Goss, 2007) using different sets of solute parameters. Predicted KP values varied by factors of 3 to over 30, depending on the compound and the model. Such discrepancies provide incentive for experimental measurements of KPA for other SVOCs.

  10. Evaluation of alternative approaches for measuring n-octanol/water partition coefficients for methodologically challenging chemicals (MCCs)

    Measurements of n-octanol/water partition coefficients (KOW) for highly hydrophobic chemicals, i.e., greater than 108, are extremely difficult and are rarely made, in part because the vanishingly small concentrations in the water phase require extraordinary analytical sensitivity...

  11. Determining octanol-water partition coefficients for extremely hydrophobic chemicals by combining 'slow stirring' and solid phase micro extraction

    Jonker, Michiel T O


    Octanol-water partition coefficients (Kow ) are widely used in fate and effects modelling of chemicals. Still, high quality experimental Kow data are scarce, in particular for very hydrophobic chemicals. This hampers reliable assessments of several fate and effect parameters and the development and

  12. Screening of octanol-water partition coefficients for pharmaceuticals by pressure-assisted microemulsion electrokinetic chromatography.

    Jia, Zhongjiang; Mei, Lijie; Lin, Fangling; Huang, Sujuan; Killion, Robert B


    A rapid screening assay for the determination of octanol-water partition coefficients (log P(OW)) of pharmaceuticals was developed by using pressure-assisted microemulsion electrokinetic chromatography (MEEKC). The microemulsion system contains 50 mM sodium dodecyl sulfate, 0.87 M l-butanol, 82 mM heptane, and 50 mM borate-phosphate (2:3) at pH 10. Ten standard compounds with known log P(OW) values from -0.26 to 4.88 were used for constructing the calibration curve of log P(OW) against the MEEKC retention factor, log k. The log P(OW) values of the compounds were calculated based on the log k values measured by MEEKC and the slope and intercept of the calibration curve. For 13 literature and 32 Roche compounds, about 90% of the log P(OW) values measured by MEEKC are within 0.5 log units of the values from the literature and potentiometric titration. The throughput is about 2 samples/h using +20 kV voltage plus 5 mbar air pressure for separation. This MEEKC method is applicable for log P(OW) screening of weakly basic, weakly acidic, and neutral pharmaceuticals with log P(OW) = 0-5 and pKa < or = 10.

  13. Determination of uranium partition coefficients of a semi-arid soil in Bahia

    Fernandes, Heloisa H.F.; Pontedeiro, Elizabeth M.; Su, Jian, E-mail:, E-mail:, E-mail: [Coordenacao dos Cursos de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Simulacao e Metodos de Engenharia; Dourado, Eneida R.G., E-mail: [Industrias Nucleares do Brasil (INB), Rio de Janeiro, RJ (Brazil)


    In mining and processing industries, the subsurface is one of the most vulnerable compartments to environmental contamination. Understanding the interactions between soil and contaminants is critical for predicting the possible environmental impacts caused by mining and milling operations. One of the main parameters used for this purpose is the partition (or distribution) coefficient, K{sub d}, which allows a relatively simple modeling approach by grouping various sorption phenomena into a single value. However, this parameter is strongly influenced by the physical and chemical characteristics of the medium, such as soil type, pH and solution composition. Thus, this study aims to assess the values of K{sub d} for uranium of typical soils from Bahia's semi-arid region using two different types of solute, one being a standard solution of uranyl acetate and one the liquor of uranium generated during processing. To calculate this parameter, batch adsorption experiments were carried out and adsorption isotherms (linear, Langmuir and Freundlich) were constructed using the Mathematica software. Results obtained for a single type of soil showed reduced values of K{sub d} for a liquor containing uranium when compared to values obtained with the uranyl acetate solution. This indicates that uranium from liquor is less adsorbed onto soil particles, and hence may move more quickly into the subsurface. (author)

  14. Zone fluidics for measurement of octanol-water partition coefficient of drugs.

    Wattanasin, Panwadee; Saetear, Phoonthawee; Wilairat, Prapin; Nacapricha, Duangjai; Teerasong, Saowapak


    A novel zone fluidics (ZF) system for the determination of the octanol-water partition coefficient (Pow) of drugs was developed. The ZF system consisted of a syringe pump with a selection valve, a holding column, a silica capillary flow-cell and an in-line spectrophotometer. Exact microliter volumes of solvents (octanol and phosphate buffer saline) and a solution of the drug, sandwiched between air segments, were sequentially loaded into the vertically aligned holding column. Distribution of the drug between the aqueous and octanol phases occurred by the oscillation movement of the syringe pump piston. Phase separation occurred due to the difference in densities. The liquid zones were then pushed into the detection flow cell. In this method, absorbance measurements in only one of the phase (octanol or aqueous) were employed, which together with the volumes of the solvents and pure drug sample, allowed the calculation of the Pow. The developed system was applied to the determination of the Pow of some common drugs. The log (Pow) values agreed well with a batch method (R(2)=0.999) and literature (R(2)=0.997). Standard deviations for intra- and inter-day analyses were both less than 0.1log unit. This ZF system provides a robust and automated method for screening of Pow values in the drug discovery process.

  15. Trophic magnification of PCBs and Its relationship to the octanol-water partition coefficient.

    Walters, David M; Mills, Marc A; Cade, Brian S; Burkard, Lawrence P


    We investigated polychlorinated biphenyl (PCB) bioaccumulation relative to octanol-water partition coefficient (K(OW)) and organism trophic position (TP) at the Lake Hartwell Superfund site (South Carolina). We measured PCBs (127 congeners) and stable isotopes (δ¹⁵N) in sediment, organic matter, phytoplankton, zooplankton, macroinvertebrates, and fish. TP, as calculated from δ¹⁵N, was significantly, positively related to PCB concentrations, and food web trophic magnification factors (TMFs) ranged from 1.5-6.6 among congeners. TMFs of individual congeners increased strongly with log K(OW), as did the predictive power (r²) of individual TP-PCB regression models used to calculate TMFs. We developed log K(OW)-TMF models for eight food webs with vastly different environments (freshwater, marine, arctic, temperate) and species composition (cold- vs warmblooded consumers). The effect of K(OW) on congener TMFs varied strongly across food webs (model slopes 0.0-15.0) because the range of TMFs among studies was also highly variable. We standardized TMFs within studies to mean = 0, standard deviation (SD) = 1 to normalize for scale differences and found a remarkably consistent K(OW) effect on TMFs (no difference in model slopes among food webs). Our findings underscore the importance of hydrophobicity (as characterized by K(OW)) in regulating bioaccumulation of recalcitrant compounds in aquatic systems, and demonstrate that relationships between chemical K(OW) and bioaccumulation from field studies are more generalized than previously recognized.

  16. Uptake rate constants and partition coefficients for vapor phase organic chemicals using semipermeable membrane devices (SPMDs)

    Cranor, W.L.; Alvarez, D.A.; Huckins, J.N.; Petty, J.D.


    To fully utilize semipermeable membrane devices (SPMDs) as passive samplers in air monitoring, data are required to accurately estimate airborne concentrations of environmental contaminants. Limited uptake rate constants (kua) and no SPMD air partitioning coefficient (Ksa) existed for vapor-phase contaminants. This research was conducted to expand the existing body of kinetic data for SPMD air sampling by determining kua and Ksa for a number of airborne contaminants including the chemical classes: polycyclic aromatic hydrocarbons, organochlorine pesticides, brominated diphenyl ethers, phthalate esters, synthetic pyrethroids, and organophosphate/organosulfur pesticides. The kuas were obtained for 48 of 50 chemicals investigated and ranged from 0.03 to 3.07??m3??g-1??d-1. In cases where uptake was approaching equilibrium, Ksas were approximated. Ksa values (no units) were determined or estimated for 48 of the chemicals investigated and ranging from 3.84E+5 to 7.34E+7. This research utilized a test system (United States Patent 6,877,724 B1) which afforded the capability to generate and maintain constant concentrations of vapor-phase chemical mixtures. The test system and experimental design employed gave reproducible results during experimental runs spanning more than two years. This reproducibility was shown by obtaining mean kua values (n??=??3) of anthracene and p,p???-DDE at 0.96 and 1.57??m3??g-1??d-1 with relative standard deviations of 8.4% and 8.6% respectively.

  17. Prediction of soot-water partition coefficients for selected persistent organic pollutants from theoretical molecular descriptors

    Qing Zhang; Jun Huang; Gang Yu


    Quantitative structure-property relationship (QSPR) models were developed for soot-water partition coefficient (KSC) values of selected persistent organic pollutants (POPs), I.e. 10 polychlorinated dibenzo-p-dioxins and dibenzofurans, nine polychlorinated biphe-nyls, four polycyclic aromatic hydrocarbons and two polybrominated diphenyl ethers, using partial least squares (PLS) regression. Quan-tum chemical descriptors computed by parameterized model revision 3 Hamiltonian method were used as predictor variables. The cross-validated Q2cum value for the optimal QSPR model is 0.844, indicating a good predictive capability for the logKsc values of these chem-icals. The QSPR results showed that average molecular polarizability (α), standard heat of formation (△Hf) and energy of the lowest unoccupied molecular orbital (ELUMO) have dominant effects on Ksc of POPs. The results suggested that logKSC values of POPs increase with the increase of α. Contrarily, logKSC values decrease with the increase of ELUMO and △Hf of POPs.

  18. Synthetic and natural Nakhla pyroxenes: Parent melt composition and REE partition coefficients

    Mckay, G.; Le, L.; Wagstaff, J.


    Nakhla is one of the SNC meteorites, generally believed to be of martian origin. It is composed mainly of cumulus augite, in which primary igneous zoning is apparently preserved, and which serves as a recorder of the composition of Nakhla's parent melt and the conditions under which it crystallized. Knowledge of the composition and petrogenesis of this parent melt may help unravel Nakhla's relationship to the other SNC's, and provide clues to martian petrogenesis in general. This abstract reports new results of an ongoing study in which we are (1) comparing the major and minor element compositions of synthetic pyroxenes crystallized from various proposed parent melt compositions with those in Nakhla pyroxene to constrain the composition of the parent melt, and (2) measuring minor and trace element partition coefficients, particularly those of the REE, in order to obtain the most applicable D values with which to invert the natural pyroxene compositions to obtain the trace element composition of the parent melt. Results suggest that recent estimates of Nakhla's parent melt composition are too aluminous, and that mafic or ultramafic melts are more likely candidates.

  19. Lab-scale experimental strategy for determining micropollutant partition coefficient and biodegradation constants in activated sludge.

    Pomiès, M; Choubert, J M; Wisniewski, C; Miège, C; Budzinski, H; Coquery, M


    The nitrifying/denitrifying activated sludge process removes several micropollutants from wastewater by sorption onto sludge and/or biodegradation. The objective of this paper is to propose and evaluate a lab-scale experimental strategy for the determination of partition coefficient and biodegradation constant for micropollutant with an objective of modelling their removal. Four pharmaceutical compounds (ibuprofen, atenolol, diclofenac and fluoxetine) covering a wide hydrophobicity range (log Kow from 0.16 to 4.51) were chosen. Dissolved and particulate concentrations were monitored for 4 days, inside two reactors working under aerobic and anoxic conditions, and under different substrate feed conditions (biodegradable carbon and nitrogen). We determined the mechanisms responsible for the removal of the target compounds: (i) ibuprofen was biodegraded, mainly under aerobic conditions by cometabolism with biodegradable carbon, whereas anoxic conditions suppressed biodegradation; (ii) atenolol was biodegraded under both aerobic and anoxic conditions (with a higher biodegradation rate under aerobic conditions), and cometabolism with biodegradable carbon was the main mechanism; (iii) diclofenac and fluoxetine were removed by sorption only. Finally, the abilities of our strategy were evaluated by testing the suitability of the parameters for simulating effluent concentrations and removal efficiency at a full-scale plant.

  20. Imidazolium ionic liquids as solvents of pharmaceuticals: influence on HSA binding and partition coefficient of nimesulide.

    Azevedo, Ana M O; Ribeiro, Diogo M G; Pinto, Paula C A G; Lúcio, Marlene; Reis, Salette; Saraiva, M Lúcia M F S


    In this work, the influence of imidazolium ionic liquids (ILs) on bio-chemical parameters that influence the in vivo behavior of nimesulide was evaluated. In this context, the binding of nimesulide to human serum albumin (HSA), in IL media, was studied. In parallel, the evaluation of the interaction of drug-IL systems, with micelles of hexadecylphosphocholine (HDPC), enabled the calculation of partition coefficients (K(p)). Both assays were performed in buffered media in the absence and in the presence of emim [BF(4)], emim [Ms] and emim [TfMs] 1%. Even though there was an increase of the dissociation constant (K(d)) in IL media, nimesulide still binds to HSA by means of strong interactions. The thermodynamic analysis indicates that the interaction is spontaneous for all the tested systems. Moreover, the studied systems exhibited properties that are favorable to the interaction of the drug with biological membranes, with K(p) values 2.5-3.5 higher than in aqueous environment. The studied nimesulide-IL systems presented promising characteristics regarding the absorption and distribution of the drug in vivo, so that the studied solvents seem to be good options for drug delivery.

  1. Concentration-dependent apparent partition coefficients of ionic liquids possessing ethyl- and bi-sulphate anions.

    Jain, Preeti; Kumar, Anil


    This study deals with the concentration dependent apparent partition coefficients log P of the ethyl and bisulfate-based ionic liquids. It is observed that the bisulfate-based ionic liquids show different behaviour with respect to concentration as compared to ethyl sulphate-based ionic liquids. It is significant and useful analysis for the further implementation of alkyl sulfate based ionic liquids as solvents in extraction processes. The log P values of the ethyl sulphate-based ionic liquids were noted to vary linearly with the concentration of the ionic liquid, whereas a flip-flop trend with the concentration for the log P values of the bisulphate-based ionic liquids was observed due to the difference in hydrogen bond accepting basicity and possibility of aggregate formation of these anions. The π-π interactions between the imidazolium and pyridinium rings were seen to affect the log P values. The alkyl chain length of anions was also observed to influence the log P values. The hydrophobicity of ionic liquid changes with the alkyl chain in the anion in the order; [HSO4](-) < [EtSO4](-) < [BuSO4](-).

  2. Measurement and analysis of the mannitol partition coefficient in sucrose crystallization under simulated industrial conditions.

    Eggleston, Gillian; Yen, Jenny Wu Tiu; Alexander, Clay; Gober, Jessica


    Mannitol is a major deterioration product of Leuconstoc mesenteroides bacterial metabolism of sucrose and fructose from both sugarcane and sugar beet. The effect of crystallization conditions on the mannitol partition coefficient (K(eff)) between impure sucrose syrup and crystal has been investigated in a batch laboratory crystallizer and a batch pilot plant-scale vacuum pan. Laboratory crystallization was operated at 65.5°C (150°F), 60.0°C (140°F), and 51.7°C (125°F) with a 78.0 Brix (% refractometric dissolved solids) pure sucrose syrup containing 0%, 0.1%, 0.2%, 1.0%, 2.0%, 3.0%, and 10% (at 65.5°C only) mannitol on a Brix basis. Produced mother liquor and crystals were separated by centrifugation and their mannitol contents measured by ion chromatography with integrated pulsed amperometric detection (IC-IPAD). The extent of mannitol partitioning into the crystals depended strongly on the mannitol concentration in the feed syrup and, to a lesser extent, the crystallization temperature. At 65.5 and 60.0°C, the K(eff) varied from ~0.4% to 3.0% with 0.2% to 3.0% mannitol in the feed syrup, respectively. The mannitol K(eff) was lower than that reported for dextran (~9-10% K(eff)), another product of Leuconstoc deterioration, under similar sucrose crystal growth conditions. At 10% mannitol concentration in the syrup at 65.5°C, co-crystallization of mannitol with sucrose occurred and the crystal growth rate was greatly impeded. In both laboratory and pilot plant crystallizations (95.7% purity; 78.0 Brix; 65.5°C), mannitol tended to cause conglomerates to form, which became progressively worse with increased mannitol syrup concentration. At the 3% mannitol concentration, crystallization at both the laboratory and pilot plant scales was more difficult. Mannitol incorporation into the sucrose crystal results mostly from liquid syrup inclusions but adsorption onto the crystal surface may play a minor role at lower mannitol concentrations.

  3. Effects of environmental temperature and dietary energy on energy partitioning coefficients of female broiler breeders.

    Pishnamazi, A; Renema, R A; Paul, D C; Wenger, I I; Zuidhof, M J


    With increasing disparity between broiler breeder target weights and broiler growth potential, maintenance energy requirements have become a larger proportion of total broiler breeder energy intake. Because energy is partitioned to growth and egg production at a lower priority than maintenance, accurate prediction of maintenance energy requirements is important for practical broiler breeder feed allocation decisions. Environmental temperature affects the maintenance energy requirement by changing rate of heat loss to the environment. In the ME system, heat production (energy lost) is part of the maintenance requirement (ME). In the current study, a nonlinear mixed model was derived to predict ME partitioning of broiler breeder hens under varied temperature conditions. At 21 wk of age, 192 Ross 708 hens were individually caged within 6 controlled environmental chambers. From 25 to 41 wk, 4 temperature treatments (15°C, 19°C, 23°C, and 27°C) were randomly assigned to the chambers for 2-week periods. Half of the birds in each chamber were fed a high-energy (HE; 2,912 kcal/kg) diet, and half were fed a low-energy (LE; 2,790 kcal/kg) diet. The nonlinear mixed regression model included a normally distributed random term representing individual hen maintenance, a quadratic response to environmental temperature, and linear ADG and egg mass (EM) coefficients. The model assumed that energy requirements for BW gain and egg production were not influenced by environmental temperature because hens were homeothermic, and the cellular processes for associated biochemical processes occurred within a controlled narrow core body temperature range. Residual feed intake (RFI) and residual ME (RME) were used to estimate efficiency. A quadratic effect of environmental temperature on broiler breeder MEm was predicted ( Birds fed the HE diet were more efficient, with a lower RME than birds on the LE diet (-0.63 vs. 0.63 kcal/kg), translating to ME of 135.2 and 136.5 kcal

  4. Assessment of PDMS-water partition coefficients: implications for passive environmental sampling of hydrophobic organic compounds

    DiFilippo, Erica L.; Eganhouse, Robert P.


    Solid-phase microextraction (SPME) has shown potential as an in situ passive-sampling technique in aquatic environments. The reliability of this method depends upon accurate determination of the partition coefficient between the fiber coating and water (Kf). For some hydrophobic organic compounds (HOCs), Kf values spanning 4 orders of magnitude have been reported for polydimethylsiloxane (PDMS) and water. However, 24% of the published data examined in this review did not pass the criterion for negligible depletion, resulting in questionable Kf values. The range in reported Kf is reduced to just over 2 orders of magnitude for some polychlorinated biphenyls (PCBs) when these questionable values are removed. Other factors that could account for the range in reported Kf, such as fiber-coating thickness and fiber manufacturer, were evaluated and found to be insignificant. In addition to accurate measurement of Kf, an understanding of the impact of environmental variables, such as temperature and ionic strength, on partitioning is essential for application of laboratory-measured Kf values to field samples. To date, few studies have measured Kf for HOCs at conditions other than at 20 degrees or 25 degrees C in distilled water. The available data indicate measurable variations in Kf at different temperatures and different ionic strengths. Therefore, if the appropriate environmental variables are not taken into account, significant error will be introduced into calculated aqueous concentrations using this passive sampling technique. A multiparameter linear solvation energy relationship (LSER) was developed to estimate log Kf in distilled water at 25 degrees C based on published physicochemical parameters. This method provided a good correlation (R2 = 0.94) between measured and predicted log Kf values for several compound classes. Thus, an LSER approach may offer a reliable means of predicting log Kf for HOCs whose experimental log Kf values are presently unavailable. Future

  5. SAMPL5: 3D-RISM partition coefficient calculations with partial molar volume corrections and solute conformational sampling

    Luchko, Tyler; Blinov, Nikolay; Limon, Garrett C.; Joyce, Kevin P.; Kovalenko, Andriy


    Implicit solvent methods for classical molecular modeling are frequently used to provide fast, physics-based hydration free energies of macromolecules. Less commonly considered is the transferability of these methods to other solvents. The Statistical Assessment of Modeling of Proteins and Ligands 5 (SAMPL5) distribution coefficient dataset and the accompanying explicit solvent partition coefficient reference calculations provide a direct test of solvent model transferability. Here we use the 3D reference interaction site model (3D-RISM) statistical-mechanical solvation theory, with a well tested water model and a new united atom cyclohexane model, to calculate partition coefficients for the SAMPL5 dataset. The cyclohexane model performed well in training and testing (R=0.98 for amino acid neutral side chain analogues) but only if a parameterized solvation free energy correction was used. In contrast, the same protocol, using single solute conformations, performed poorly on the SAMPL5 dataset, obtaining R=0.73 compared to the reference partition coefficients, likely due to the much larger solute sizes. Including solute conformational sampling through molecular dynamics coupled with 3D-RISM (MD/3D-RISM) improved agreement with the reference calculation to R=0.93. Since our initial calculations only considered partition coefficients and not distribution coefficients, solute sampling provided little benefit comparing against experiment, where ionized and tautomer states are more important. Applying a simple pK_{ {a}} correction improved agreement with experiment from R=0.54 to R=0.66, despite a small number of outliers. Better agreement is possible by accounting for tautomers and improving the ionization correction.

  6. Sediment-to-Water Partition Coefficients: the Influence of Physicochemical and Seasonal Factors in Eastern Ontario

    Yankovich, Tamara L. [International Atomic Energy Agency, P.O. Box 100, 1400 Vienna (Austria); Shultz, Carmen; Hartwig, Dale; Wills, C. Anne [Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, K0J 1J0 (Canada); Beresford, Nicholas A. [NERC Centre for Ecology and Hydrology, Lancaster Environment Center, Library Av., Bailrigg, Lancaster, LA1 4AP (United Kingdom); School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom); Wood, Michael D. [School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom)


    Sediments often represent an important reservoir for contaminants, such as radionuclides and metals, in aquatic ecosystems. Consequently, lake, stream, and river sediments can potentially act as significant contributors to the total contaminant exposure and radiological doses received by wildlife. Exposure to contaminated sediments is dependent upon several factors. These include net contaminant inputs to a system through time, the physicochemical attributes of the system, the tendency of each contaminant to partition into the sediments relative to water, the spatial distribution of contaminants in the sediments, and the behaviour or life-style of the biota inhabiting a water body. Increased understanding of such factors and their interactions will lead to improved predictions of the radionuclide exposure received by aquatic biota, particularly benthic organisms. Despite the complexity and the dynamic nature of sediments in general, for practical purposes, in environmental impact assessments (EIAs), it is often assumed that radionuclide activity concentrations in various compartments are at steady state with respect to one another. Therefore, ratios can be used to estimate concentrations in one compartment given a known concentration in another. In the case of sediments, sediment-to-water partition coefficients (K{sub d}) are often applied to estimate the contaminant concentration sorbed to particulate matter relative to the concentration measured in the surface water. However, K{sub d} values often range by several orders of magnitude between sampling locations due to site-specific differences in physicochemical conditions in surface waters, seasonal factors, as well as differences in sediment attributes that can affect contaminant partitioning between the dissolved and particulate phases. Consequently, in conducting EIAs, it becomes necessary to either apply generic K{sub d} values that ensure contaminant concentrations in sediments to which biota are exposed are

  7. Simulations of mean ionic activity coefficients and solubilities in aqueous electrolyte solutions

    Panagiotopoulos, Athanassios

    Aqueous electrolyte solutions play an important role in industrial, geochemical and biological applications. The mean ionic activity coefficients quantify the deviation of salt chemical potential from ideal solution behavior; experimental measurements are available for many salts over broad ranges of concentration and temperature, but there have been practically no prior simulation results, because if sampling difficulties for explicit-solvent electrolyte solutions. We have developed a new approach for determination of activity coefficients of aqueous electrolytes. Common fixed-point-charge models for water and ions are unable to reproduce simultaneously activity coefficients and solubilities. Polarizable models perform better, but still predict an incorrect temperature dependence of these properties. Work supported by the U.S. Department of Energy, Office of Basic Energy Science.

  8. Prediction of air-to-blood partition coefficients of volatile organic compounds using genetic algorithm and artificial neural network

    Konoz, Elahe [Department of Chemistry, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Golmohammadi, Hassan [Department of Chemistry, Mazandaran University, Babolsar (Iran, Islamic Republic of)], E-mail:


    An artificial neural network (ANN) was constructed and trained for the prediction of air-to-blood partition coefficients of volatile organic compounds. The inputs of this neural network are theoretically derived descriptors that were chosen by genetic algorithm (GA) and multiple linear regression (MLR) features selection techniques. These descriptors are: R maximal autocorrelation of lag 1 weighted by atomic Sanderson electronegativities (R1E+), electron density on the most negative atom in molecule (EDNA), maximum partial charge for C atom (MXPCC), surface weighted charge partial surface area (WNSA1), fractional charge partial surface area (FNSA2) and atomic charge weighted partial positive surface area (PPSA3). The standard errors of training, test and validation sets for the ANN model are 0.095, 0.148 and 0.120, respectively. Result obtained showed that nonlinear model can simulate the relationship between structural descriptors and the partition coefficients of the molecules in data set accurately.

  9. Partitioning of water soluble organic carbon in three sediment size fractions: Effect of the humic substances

    SUN Liying; SUN Weiling; NI Jinren


    Water soluble organic carbon (WSOC) in sediments plays an important role in transference and transformation of aquatic pollutants. This article investigated the inherent mechanisms of how sediemnt grain size affect the partitioning coeffcient (k) of WSOC. Influences of NaOH extracted humic substances were particularly focused on. Sediments were sampled from two cross-sections of the middle Yellow River and sieved into three size fractions (< 63 μm, 63-100 μm, and 100--300 μm). The total concentration of WSOC in sediments (CWSOC) and k were estimated using multiple water-sediment ratio experiments. Results show that CWSOC ranges from 0.012 to 0.022 mg/g, while k ranges from 0.8 to 3.9 L/kg. Correlations between the spectrum characteristics of NaOH extracted humic substances and k were analyzed. Strong positive correlations are determined between k and the aromaticity indicators of NaOH extracted humic substances in different sediment size fractions. Comparing with finer fractions (< 63 μm), k is higher in larger size fractions (63--100 and 100--300 μm) related to higher aromaticity degree of NaOH extracted humic substances mostly. While negative relationship between k and the area ratio of fourier transform infrared spectroscopy (FT-IR) at 3400 and 1430 cm-1 implied that the lowest k was related to the highest concentration of the acidic humic groups in particles < 63 μm. WSOC in finer fractions (< 63 μm) is likely to enter into pore water, which may further accelerate the transportation of aquatic contaminants from sediment to water.

  10. A simple method to optimize the HSCCC two-phase solvent system by predicting the partition coefficient for target compound.

    Han, Quan-Bin; Wong, Lina; Yang, Nian-Yun; Song, Jing-Zheng; Qiao, Chun-Feng; Yiu, Hillary; Ito, Yoichiro; Xu, Hong-Xi


    A simple method was developed to optimize the solvent ratio of the two-phase solvent system used in the high-speed counter-current chromatography (HSCCC) separation. Some mathematic equations, such as the exponential and the power equations, were established to describe the relationship between the solvent ratio and the partition coefficient. Using this new method, the two-phase solvent system was easily optimized to obtain a proper partition coefficient for the CCC separation of the target compound. Furthermore, this method was satisfactorily applied in determining the two-phase solvent system for the HSCCC preparation of pseudolaric acid B from the Chinese herb Pseudolarix kaempferi Gordon (Pinaceae). The two-phase solvent system of n-hexane/EtOAc/MeOH/H(2)O (5:5:5:5 by volume) was used with a good partition coefficient K = 1.08. As a result, 232.05 mg of pseudolaric acid B was yielded from 0.5 g of the crude extract with a purity of 97.26% by HPLC analysis.

  11. Comparison of Automated Continuous Flow Method With Shake- Flask Method in Determining Partition Coefficients of Bidentate Hydroxypyridinone Ligands

    Lotfollah Saghaie


    Full Text Available The partition coefficients (Kpart , in octanol/water system of a range of bidentate ligands containing the 3-hydroxypyridin-4-one moiety were determined using shake flask and automated continuous flow methods (filter probe method. The shake flask method was used for extremely hydrophilic or hydrophobic compounds with a Kpart values greater than 100 and less than 0.01. For other ligands which possess moderate lipophilicity (Kpart values between 0.01-100 the filter probe method was used. Also the partition coefficient of four ligands with moderate lipophilicity was determined by shake flask method in order to check comparability of these two methods. While the shake flask method was able to determine either extremely hydrophilic or hydrophobic compounds efficiently, the filter probe method was unable to measure such Kpart values. Although, determination of the Kpart values of all compounds is possible with the classical shake-flask method, the procedure is time consuming. In contrast, the filter probe method offers many advantages over the traditional shake-flask method in terms of speed, efficiency of separation and degree of automation. The shake-flask method is the method of choice for determination of partition coefficients of extremely hydrophilic and hydrophobic ligands.

  12. Determination and importance of temperature dependence of retention coefficient (RPHPLC) in QSAR model of nitrazepams' partition coefficient in bile acid micelles.

    Posa, Mihalj; Pilipović, Ana; Lalić, Mladena; Popović, Jovan


    Linear dependence between temperature (t) and retention coefficient (k, reversed phase HPLC) of bile acids is obtained. Parameters (a, intercept and b, slope) of the linear function k=f(t) highly correlate with bile acids' structures. Investigated bile acids form linear congeneric groups on a principal component (calculated from k=f(t)) score plot that are in accordance with conformations of the hydroxyl and oxo groups in a bile acid steroid skeleton. Partition coefficient (K(p)) of nitrazepam in bile acids' micelles is investigated. Nitrazepam molecules incorporated in micelles show modified bioavailability (depo effect, higher permeability, etc.). Using multiple linear regression method QSAR models of nitrazepams' partition coefficient, K(p) are derived on the temperatures of 25°C and 37°C. For deriving linear regression models on both temperatures experimentally obtained lipophilicity parameters are included (PC1 from data k=f(t)) and in silico descriptors of the shape of a molecule while on the higher temperature molecular polarisation is introduced. This indicates the fact that the incorporation mechanism of nitrazepam in BA micelles changes on the higher temperatures. QSAR models are derived using partial least squares method as well. Experimental parameters k=f(t) are shown to be significant predictive variables. Both QSAR models are validated using cross validation and internal validation method. PLS models have slightly higher predictive capability than MLR models.

  13. Solubility parameter and activity coefficient of HDEHP dimer in select organic diluents by vapor pressure osmometry

    Gray, M.; Nilsson, M. [University of California Irvine, 916 Engineering Tower, UC Irvine, Irvine, CA 92697-2575 (United States); Zalupski, P. [Idaho National Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83415 (United States)


    A thorough understanding of the non-ideal behavior of the chemical components utilized in solvent extraction contributes to the success of any large-scale spent nuclear fuel treatment. To address this, our current work uses vapor pressure osmometry to characterize the non-ideal behavior of the solvent extraction agent di-(2-ethylhexyl) phosphoric acid (HDEHP), a common extractant in proposed separation schemes. Solubility parameters were fit to data on HDEHP at four temperatures using models based on Scatchard Hildebrand regular solution theory with Flory Huggins entropic corrections. The results are comparable but not identical to the activity coefficients from prior slope analysis in the literature. (authors)

  14. Solvation free energies and partition coefficients with the coarse-grained and hybrid all-atom/coarse-grained MARTINI models

    Genheden, Samuel


    We present the estimation of solvation free energies of small solutes in water, n-octanol and hexane using molecular dynamics simulations with two MARTINI models at different resolutions, viz. the coarse-grained (CG) and the hybrid all-atom/coarse-grained (AA/CG) models. From these estimates, we also calculate the water/hexane and water/octanol partition coefficients. More than 150 small, organic molecules were selected from the Minnesota solvation database and parameterized in a semi-automatic fashion. Using either the CG or hybrid AA/CG models, we find considerable deviations between the estimated and experimental solvation free energies in all solvents with mean absolute deviations larger than 10 kJ/mol, although the correlation coefficient is between 0.55 and 0.75 and significant. There is also no difference between the results when using the non-polarizable and polarizable water model, although we identify some improvements when using the polarizable model with the AA/CG solutes. In contrast to the estimated solvation energies, the estimated partition coefficients are generally excellent with both the CG and hybrid AA/CG models, giving mean absolute deviations between 0.67 and 0.90 log units and correlation coefficients larger than 0.85. We analyze the error distribution further and suggest avenues for improvements.

  15. Cyclic voltammetric technique for the determination of the critical micelle concentration of surfactants, self-diffusion coefficient of micelles, and partition coefficient of an electrochemical probe

    Mandal, A.B.; Nair, B.U. (Central Leather Research Inst., Madras (India))


    Critical micelle concentrations (cmc) of cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC) surfactants in aqueous solution have been determined by using the cyclic voltammetric technique. (Co(en){sub 3})(ClO{sub 4}){sub 3} has been used as the redox-active electrochemical probe. The cmc values so obtained for the surfactants were found to be in good agreement with the literature values. The partition coefficient, K, of the electrochemical probe between water and surfactants in nonmicellar and micellar states was estimated using the peak current, i{sub p} and half-wave potential, E{sub 1/2} values. The self-diffusion coefficient, D{sub m}, interaction parameter, k{sub f}, and hydrodynamic radius of the micelles were also estimated. The results suggest that the probe is sensitive to the nature of surfactant as well as surfactant concentration.

  16. Influence of substrate partition coefficient on the performance of lipase catalyzed synthesis of citronellyl acetate by alcoholysis

    H.F. Castro


    Full Text Available The enzymatic synthesis of selected low molecular weight esters such as acetate esters by direct esterification using acetic acid as acyl donor usually display low yields. The acetic acid changes the polarity of the reaction medium, which in this turn modifies the partitioning of water between the solid phase (enzyme preparation and the liquid phase (substrate, resulting in its accumulation on the enzyme solid phase. This may reduce the enzyme´s local pH. Therefore, the enzyme active site is modified and the reaction became nearly impossible. Our previous work showed that there is a negative relationship between enzyme activity and substrate partition coefficient (Ps; that is, the higher the substrate partition coefficient the lower the amount of product formed. This work investigated the feasibility of minimizing this inhibition by replacing the esterification reaction for alcoholysis reaction using several acetate esters. This approach enhanced the reaction yields to 46%, which is about 3 times higher than that one obtained in the esterification route.

  17. Second derivative spectrophotometric determination of partition coefficients of phenothiazine derivatives between human erythrocyte ghost membranes and water.

    Kitamura, K; Goto, T; Kitade, T


    The absorption spectra of six phenothiazine derivatives, chlorpromazine, triflupromazine, promazine, promethazine, trifluoperazine and prochlorperazine, measured in the solutions containing various amounts of human erythrocyte ghosts (HEG) showed bathocromic shifts according to the amount of HEG. Due to the strong background signals caused by HEG, the baseline compensation was incomplete, even though the sample and the reference solutions contained the same amount of HEG, hence further spectral information could not be obtained. The second derivative spectra of these absorption spectra clearly showed the derivative isosbestic points, indicating that the residual background signal effects were entirely eliminated. The derivative intensity differences of the phenothiazines (DeltaD values) before and after the addition of HEG were measured at a specific wavelength. Using the DeltaD values, the partition coefficients (K(p)) of these drugs were calculated and obtained with R.S.D. of below 10 %. The fractions of partitioned phenothiazines calculated from the K(p) values agreed well with the experimental values. The results indicate that the derivative method can be applicable to the determination of partition coefficients of drugs to HEG without any separation procedures.

  18. 1-Octanol/Water Partition Coefficients of n-Alkanes from Molecular Simulations of Absolute Solvation Free Energies.

    Garrido, Nuno M; Queimada, António J; Jorge, Miguel; Macedo, Eugénia A; Economou, Ioannis G


    The 1-octanol/water partition coefficient is an important thermodynamic variable usually employed to understand and quantify the partitioning of solutes between aqueous and organic phases. It finds widespread use in many empirical correlations to evaluate the environmental fate of pollutants as well as in the design of pharmaceuticals. The experimental evaluation of 1-octanol/water partition coefficients is an expensive and time-consuming procedure, and thus, theoretical estimation methods are needed, particularly when a physical sample of the solute may not yet be available, such as in pharmaceutical screening. 1-Octanol/water partition coefficients can be obtained from Gibbs free energies of solvation of the solute in both the aqueous and the octanol phases. The accurate evaluation of free energy differences remains today a challenging problem in computational chemistry. In order to study the absolute solvation Gibbs free energies in 1-octanol, a solvent that can mimic many properties of important biological systems, free energy calculations for n-alkanes in the range C1-C8 were performed using molecular simulation techniques, following the thermodynamic integration approach. In the first part of this paper, we test different force fields by evaluating their performance in reproducing pure 1-octanol properties. It is concluded that all-atom force fields can provide good accuracy but at the cost of a higher computational time compared to that of the united-atom force fields. Recent versions of united-atom force fields, such as Gromos and TraPPE, provide satisfactory results and are, thus, useful alternatives to the more expensive all-atom models. In the second part of the paper, the Gibbs free energy of solvation in 1-octanol is calculated for several n-alkanes using three force fields to describe the solutes, namely Gromos, TraPPE, and OPLS-AA. Generally, the results obtained are in excellent agreement with the available experimental data and are of similar

  19. Assessing FAO-56 dual crop coefficients using eddy covariance flux partitioning

    Current approaches to scheduling crop irrigation using reference evapotranspiration (ET0) recommend using a dual-coefficient approach using basal (Kcb) and soil (Ke) coefficients along with a stress coefficient (Ks) to model crop evapotranspiration (ETc), [e.g. ETc=(Ks*Kcb+Ke)*ET0]. However, determi...

  20. Experimental mineral/liquid partition coefficients of the rare earth elements /REE/, Sc and Sr for perovskite, spinel and melilite

    Nagasawa, H.; Schreiber, H. D.; Morris, R. V.


    Experimental determinations of the mineral/liquid partition coefficients of REE (La, Sm, Eu, Gd, Tb, Yb and Lu), Sc and Sr are reported for the minerals perovskite, spinel and melilite in synthetic systems. Perovskite concentrates light REE with respect to the residual liquid but shows no preference for heavy REE. Spinel greatly discriminates against the incorporation of REE, especially light REE, into its crystal structure. The partition of REE into melilite from a silicate liquid is quite dependent upon both the bulk melt and melilite solid-solution (gehlenite and akermanite components) compositions. As such, melilite can be enriched in REE or will reject REE with corresponding strong negative or strong positive Eu anomalies, respectively.

  1. An empirical study of statistical properties of variance partition coefficients for multi-level logistic regression models

    Li, J.; Gray, B.R.; Bates, D.M.


    Partitioning the variance of a response by design levels is challenging for binomial and other discrete outcomes. Goldstein (2003) proposed four definitions for variance partitioning coefficients (VPC) under a two-level logistic regression model. In this study, we explicitly derived formulae for multi-level logistic regression model and subsequently studied the distributional properties of the calculated VPCs. Using simulations and a vegetation dataset, we demonstrated associations between different VPC definitions, the importance of methods for estimating VPCs (by comparing VPC obtained using Laplace and penalized quasilikehood methods), and bivariate dependence between VPCs calculated at different levels. Such an empirical study lends an immediate support to wider applications of VPC in scientific data analysis.

  2. The double isotope technique for in vivo determination of the tissue-to-blood partition coefficient for xenon in human subcutaneous adipose tissue--an evaluation

    Jelnes, Rolf; Astrup, A; Bülow, J


    technique reduces the coefficient of variation on average flow determinations, thus an improvement in accuracy of local blood flow estimation can be obtained compared to the method in which an average partition coefficient is used. For long-term studies a partition coefficient of 7.5 ml g-1 seems valid.......Local subcutaneous 133xenon (133Xe) elimination was registered in the human forefoot in 34 patients. The tissue/blood partition coefficient for Xe was estimated individually by simultaneous registration of 133Xe and [131I]antipyrine ([131I]AP) washout from the same local depot. When measured...... in this way, an average partition coefficient for Xe was found to be 4.3 +/- 1.23 ml g-1. This value is significantly lower than the partition coefficient found in a previous in vitro study in which a Xe partition coefficient of 7.5 +/- 1.57 ml g-1 was found. Thus, if the local blood flow is calculated using...

  3. The partitioning of sulfur and chlorine between andesite melts and magmatic volatiles and the exchange coefficients of major cations

    Zajacz, Zoltán; Candela, Philip A.; Piccoli, Philip M.; Sanchez-Valle, Carmen


    Andesite melts were equilibrated with an H-O-S-bearing volatile phase to determine the partition coefficients for S and Cl as a function of melt composition and oxygen fugacity. The experiments were conducted in rapid-quench MHC vessel assemblies at 200 MPa and 1000 °C, and over a range of imposed fO2 between NNO-1.2 and NNO+1.8. High fluid/melt mass ratios (∼15) were employed, allowing precise and accurate partition coefficients to be obtained by mass balance calculations. Chlorine exhibits Henrian behavior at ClO-0.5 activities typical for arc magmas, with D Cl volatile/melt = 1.36 ± 0.06 (1σ) below 0.2 wt.% Cl in the melt; at higher ClO-0.5 activities, D Cl volatile/melt increases linearly to 2.11 ± 0.02 at 1 wt.% Cl in the melt. In the volatile phase: FeCl2 ∼ NaCl > KCl ∼ HCl. The determination of cation exchange coefficients for major cations yielded: K K,Na volatile/melt = 1.23 ± 0.10 (1σ) and ∗K Fe,Na volatile/melt = D Fe volatile/melt / D Na volatile/melt = 1.08 ± 0.16 (1σ). Under these conditions, the concentration of HCl in the vapor is negatively correlated with the (Na + K)/(Al + Fe3+) ratio in the melt. Reduced sulfur (S2-) appears to obey Henry's law in andesite melt-volatile system at fH2S below pyrrhotite saturation. The partition coefficient for S at fO2 = NNO-0.5 correlates negatively with the FeO concentration in the melt, changing from 254 ± 25 at 4.0 wt.% FeO to 88 ± 6 at 7.5 wt.% FeO. Pyrrhotite saturation is reached when approximately 3.2 mol% S is present in the volatile phase at fO2 = NNO-0.5. At the sulfide/sulfate transition, the partition coefficient of S drops from 171 ± 23 to 21 ± 1 at a constant FeO content of ∼6 wt.% in the melt. At fO2 = NNO+1.8, anhydrite saturation is reached at ∼3.3 mol% S present in the volatile phase. Aqueous volatiles exsolving from intermediate to mafic magmas can efficiently extract S, and effect its transfer to sites of magmatic-hydrothermal ore deposit formation.

  4. In Situ Raman Spectroscopic Study of the Diffusion Coefficients and Solubility:Indicates to Carbon Dioxide Injection into Hexadecane

    Wu, Dan; Lu, Wanjun


    Injecting CO2 into lean-oil reservoirs is not only a way to geological storage but also enhanced oil recovery. In the secondary displacements of oil reservoir by CO2-injection, diffusion coefficients and solubility of CO2 are key parameters to calculate the volume of CO2 injected and the time to achieve the desired viscosity in the numerical simulation. Unfortunately, the experimental data on the CO2 diffusion coefficient and solubility in liquid hydrocarbons under high pressure conditions are scarce. Hexadecane has properties similar to the average properties of Brazilian heavy oil. Experimental data on the diffusion coefficients and solubility of CO2 in hexadecane were reviewed by Nieuwoudt and Rand (2002), Rincon and Trejo (2001) and Breman et al (1994), indicating that the data in the literature were limited at relatively low temperatures and/or low pressures. In this paper, the diffusion coefficients of carbon dioxide in hexadecane at different temperature and pressure were determined with in situ Raman spectroscopy. A model was established to describe relationship among diffusion coefficients, temperature, and pressure. The solubility of CO2 in hexadecane was obtained from 298.15 to 473.15 K and 10 to 45 MPa. The experimental results show that:(1) Solubility of CO2 decreases with increasing temperature.(2) Increasing pressure increases the CO2 solubility. in terms of the degree of influence,100K is similar with 10MPa.(3) Diffusion coefficients of CO2 increases with increasing temperature. (4) Increasing pressure decreases the CO2 diffusion coefficients, whereas the pressure effect on CO2 diffusion coefficients is very weak. Compared with traditional sampling and analytical methods, the advantages of our method include: (1) the use of in situ Raman signals for solubility measurements eliminates possible uncertainty caused by sampling and ex situ analysis. (2) it is simple and efficient, and (3) high-pressure data can be obtained safely.

  5. Bioaccumulation Patterns Of PCBs In A Temperate, Freshwater Food Web And Their Relationshop To The Octanol-Water Partition Coefficient (Presentation)

    We investigated polychlorinated biphenyl (PCB) bioaccumulation relative to octanol-water partition coefficient (KOW) and organism tropic position (TP) at the Lake Hartwell Superfund site (South Carolina, USA). We measured PCBs (127 congeners) and stable isotopes (δ

  6. Studies on Partition Coefficient and its Normalization%划分系数与归一化型的比较研究

    吴成茂; 李彦; 范九伦


    对J.C.Bezdek提出的划分系数,基于样本最大分类信息的改进划分系数,以及二者的归一化形式的分类性能进行了实验分析,结果表明,归一化处理的分类性能有明显提高。%In this paper,classification performances of J.C.Bezdek's partition coefficient,improved partition coefficient based on maximum classification information and two kinds of normalized partition coefficients are experimented and analyzed ,the conclusion shows that classification performance of two kinds of normalized partition coefficient is improved markedly.

  7. Determination of octanol-air partition coefficients and supercooled liquid vapor pressures of PAHs as a function of temperature: Application to gas-particle partitioning in an urban atmosphere

    Odabasi, Mustafa; Cetin, Eylem; Sofuoglu, Aysun

    Octanol-air partition coefficients ( KOA) for 14 polycyclic aromatic hydrocarbons (PAHs) were determined as a function of temperature using the gas chromatographic retention time method. log KOA values at 25° ranged over six orders of magnitude, between 6.34 (acenaphthylene) and 12.59 (dibenz[ a,h]anthracene). The determined KOA values were within factor of 0.7 (dibenz[ a,h]anthracene) to 15.1 (benz[ a]anthracene) of values calculated as the ratio of octanol-water partition coefficient to dimensionless Henry's law constant. Supercooled liquid vapor pressures ( PL) of 13 PAHs were also determined using the gas chromatographic retention time technique. Activity coefficients in octanol calculated using KOA and PL ranged between 3.2 and 6.2 indicating near-ideal solution behavior. Atmospheric concentrations measured in this study in Izmir, Turkey were used to investigate the partitioning of PAHs between particle and gas-phases. Experimental gas-particle partition coefficients ( Kp) were compared to the predictions of KOA absorption and KSA (soot-air partition coefficient) models. Octanol-based absorptive partitioning model predicted lower partition coefficients especially for relatively volatile PAHs. Ratios of measured/modeled partition coefficients ranged between 1.1 and 15.5 (4.5±6.0, average±SD) for KOA model. KSA model predictions were relatively better and measured to modeled ratios ranged between 0.6 and 5.6 (2.3±2.7, average±SD).

  8. [Evaluation on contribution rate of each component total salvianolic acids and characterization of apparent oil/water partition coefficient].

    Yan, Hong-mei; Chen, Xiao-yun; Xia, Hai-jian; Liu, Dan; Jia, Xiao-bin; Zhang, Zhen-hai


    The difference between three representative components of total salvianolic acids in pharmacodynamic activity were compared by three different pharmacological experiments: HUVECs oxidative damage experiment, 4 items of blood coagulation in vitro experiment in rabbits and experimental myocardial ischemia in rats. And the effects of contribution rate of each component were calculated by multi index comprehensive evaluation method based on CRITIC weights. The contribution rates of salvianolic acid B, rosmarinic acid and Danshensu were 28.85%, 30.11%, 41.04%. Apparent oil/water partition coefficient of each representative components of total salvianolic acids in n-octyl alcohol-buffer was tested and the total salvianolic acid components were characterized based on a combination of the approach of self-defined weighting coefficient with effects of contribution rate. Apparent oil/water partition coefficient of total salvianolic acids was 0.32, 1.06, 0.89, 0.98, 0.90, 0.13, 0.02, 0.20, 0.56 when in octanol-water/pH 1.2 dilute hydrochloric acid solution/ pH 2.0, 2.5, 5.0, 5.8, 6.8, 7.4, 7.8 phosphate buffer solution. It provides a certain reference for the characterization of components.

  9. 40 CFR 799.6755 - TSCA partition coefficient (n-octanol/water), shake flask method.


    ... organometallic compounds. (4) Alternative methods. High-pressure liquid chromatography (HPLC) methods described... coefficient by high pressure liquid chromatography. Journal of Medicinal Chemistry 19:615 (1976). (6)...

  10. Determination of partition coefficient and analysis of nitrophenols by three-phase liquid-phase microextraction coupled with capillary electrophoresis.

    Sanagi, Mohd Marsin; Miskam, Mazidatulakmam; Wan Ibrahim, Wan Aini; Hermawan, Dadan; Aboul-Enein, Hassan Y


    A three-phase hollow fiber liquid-phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1-octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 microL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H(3)PO(4), pH 3.0; organic solvent, 1-octanol; acceptor solution, 40 microL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05-0.30 mg/L with r(2)>0.9900 and LODs were in the range of 0.01-0.04 mg/L with RSDs of 1.25-2.32%. Excellent enrichment factors of up to 398-folds were obtained. It was found that the partition coefficient (K(a/d)) values were high for 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2,6-dinitrophenol and that the individual partition coefficients (K(org/d) and K(a/org)) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.

  11. Evaluation of long-range transport potential of selected brominated flame retardants with measured 1-octanol-air partition coefficients

    Lee, Hyun Jeong; Kwon, Jung Hwan [Div. of Environmental Science and Ecological Engineering, Korea University, Seoul (Korea, Republic of)


    Various alternative flame retardants are used in many countries since polybrominated diphenyl ethers (PBDEs) were classified as persistent organic pollutants (POPs). However, difficulties in the evaluation of the long-range transport potential (LRTP) of the alternatives are related to the lack of information on their physicochemical properties, which govern their environmental fates and transport. Based on the simulation of LRTP using OECD P{sub OV} and LRTP Screening Tool, five alternative brominated flame retardants (BFRs) (hexabromobenzene [HBB], 2,3,4,5,6-pentabromotoluene [PBT], 2,3,4,5,6-pentabromoethylbenzene [PBEB], 2-ethylhexyl 2,3,4,5-tetrabromobenzoate [TBB], and 1,2,4,5-tetrabromo-3,6-dimethylbenzene [TBX]), and 3 PBDEs (BDE-28, BDE-47, and BDE-99) were chosen to perform a refined assessment. This was done using an experimentally measured 1-octanol–air partition coefficient (K{sub OA}) for the calculation of the air–water partition coefficient (K{sub AW}) required for the model. The four selected alternative BFRs (HBB, PBT, PBEB, TBX) have K{sub OA} values close to the in silico estimation used in the screening evaluation. On the other hand, the measured K{sub OA} value for TBB was two orders of magnitude lower than the estimated value used in the screening simulation. The refined simulation showed that characteristic travel distance (CTD) and transfer efficiency (TE) for HBB, PBT, PBEB, and TBX were greater than those for BDE-28, whereas CTD and TE for TBB were lower than those for BDE-28. This suggested that TBB has a lower LRTP than BDE-28, considering the refined partition coefficients.

  12. Trace element abundances in megacrysts and their host basalts - Constraints on partition coefficients and megacryst genesis

    Irving, A. J.; Frey, F. A.


    Rare earth and other trace element abundances are determined in megacrysts of clinopyroxene, orthopyroxene, amphibole, mica, anorthoclase, apatite and zircon, as well as their host basalts, in an effort to gather data on mineral/melt trace element partitioning during the high pressure petrogenesis of basic rocks. Phase equilibria, major element partitioning and isotopic ratio considerations indicate that while most of the pyroxene and amphibole megacrysts may have been in equilibrium with their host magmas at high pressures, mica, anorthoclase, apatite, and zircon megacrysts are unlikely to have formed in equilibrium with their host basalts. It is instead concluded that they were precipitated from more evolved magmas, and have been mixed into their present hosts.

  13. The Nakhla parent melt: REE partition coefficients and clues to major element composition

    Mckay, G.; Le, L.; Wagstaff, J.


    Nakhla is one of the SNC meteorites, generally believed to be of Martian origin. It is a medium-grained augite-olivine cumulate with a variolitic groundmass of sodic plagioclase, alkali feldspar, and Fe-rich pyroxenes and olivine. One of the major tasks in deciphering Nakhla's petrogenesis is determining the composition of its parent melt. Gaining an understanding of the composition and petrogenesis of this parent melt may help unravel Nakhla's relationship to the other SNCs, and provide clues to Martian petrogenesis in general. Our experimental partitioning studies provide new information that helps constrain both the major and trace element composition of the Nakhla parent melt.

  14. Feasibility of a simple laboratory approach for determining temperature influence on SPMD-air partition coefficients of selected compounds

    Cicenaite, A.; Huckins, J.N.; Alvarez, D.A.; Cranor, W.L.; Gale, R.W.; Kauneliene, V.; Bergqvist, P.-A.


    Semipermeable membrane devices (SPMDs) are a widely used passive sampling methodology for both waterborne and airborne hydrophobic organic contaminants. The exchange kinetics and partition coefficients of an analyte in a SPMD are mediated by its physicochemical properties and certain environmental conditions. Controlled laboratory experiments are used for determining the SPMD-air (Ksa's) partition coefficients and the exchange kinetics of organic vapors. This study focused on determining a simple approach for measuring equilibrium Ksa's for naphthalene (Naph), o-chlorophenol (o-CPh) and p-dichlorobenzene (p-DCB) over a wide range of temperatures. SPMDs were exposed to test chemical vapors in small, gas-tight chambers at four different temperatures (-16, -4, 22 and 40 ??C). The exposure times ranged from 6 h to 28 d depending on test temperature. Ksa's or non-equilibrium concentrations in SPMDs were determined for all compounds, temperatures and exposure periods with the exception of Naph, which could not be quantified in SPMDs until 4 weeks at the -16 ??C temperature. To perform this study the assumption of constant and saturated atmospheric concentrations in test chambers was made. It could influence the results, which suggest that flow through experimental system and performance reference compounds should be used for SPMD calibration. ?? 2006 Elsevier Ltd. All rights reserved.


    Zeng, Yun; Liu, Gang; Ma, Ying; Chen, Xiaoyuan; Ito, Yoichiro


    A new series of organic-high ionic strength aqueous two-phase solvents systems was designed for separation of highly polar compounds by spiral high-speed counter-current chromatography. A total of 21 solvent systems composed of 1-butanol-ethanol-saturated ammonium sulfate-water at various volume ratios are arranged according to an increasing order of polarity. Selection of the two-phase solvent system for a single compound or a multiple sample mixture can be achieved by two steps of partition coefficient measurements using a graphic method. The capability of the method is demonstrated by optimization of partition coefficient for seven highly polar samples including tartrazine (K=0.77), tryptophan (K=1.00), methyl green (K= 0.93), tyrosine (0.81), metanephrine (K=0.89), tyramine (K=0.98), and normetanephrine (K=0.96). Three sulfonic acid components in D&C Green No. 8 were successfully separated by HSCCC using the graphic selection of the two-phase solvent system.

  16. Feasibility of a simple laboratory approach for determining temperature influence on SPMD–air partition coefficients of selected compounds

    Cicenaite, Aurelija; Huckins, James N.; Alvarez, David A.; Cranor, Walter L.; Gale, Robert W.; Kauneliene, Violeta; Bergqvist, Per-Anders


    Semipermeable membrane devices (SPMDs) are a widely used passive sampling methodology for both waterborne and airborne hydrophobic organic contaminants. The exchange kinetics and partition coefficients of an analyte in a SPMD are mediated by its physicochemical properties and certain environmental conditions. Controlled laboratory experiments are used for determining the SPMD–air (Ksa's) partition coefficients and the exchange kinetics of organic vapors. This study focused on determining a simple approach for measuring equilibrium Ksa's for naphthalene (Naph), o-chlorophenol (o-CPh) and p-dichlorobenzene (p-DCB) over a wide range of temperatures. SPMDs were exposed to test chemical vapors in small, gas-tight chambers at four different temperatures (−16, −4, 22 and 40 °C). The exposure times ranged from 6 h to 28 d depending on test temperature. Ksa's or non-equilibrium concentrations in SPMDs were determined for all compounds, temperatures and exposure periods with the exception of Naph, which could not be quantified in SPMDs until 4 weeks at the −16 °C temperature. To perform this study the assumption of constant and saturated atmospheric concentrations in test chambers was made. It could influence the results, which suggest that flow through experimental system and performance reference compounds should be used for SPMD calibration.

  17. The effect of oil-water partition coefficient on the distribution and cellular uptake of liposome-encapsulated gold nanoparticles.

    Bao, Quan-Ying; Liu, Ai-Yun; Ma, Yu; Chen, Huan; Hong, Jin; Shen, Wen-Bin; Zhang, Can; Ding, Ya


    The shape, size, and surface features of nanoparticles greatly influence the structure and properties of resulting hybrid nanosystems. In this work, gold nanoparticles (GNPs) were modified via S-Au covalent bonding by glycol monomethyl ether thioctate with poly(ethylene glycol) methyl ether of different molecular weights (i.e., 350, 550, and 750Da). These modified GNPs (i.e., GNP350, GNP550, and GNP750) showed different oil-water partition coefficients (Kp), as detected using inductively coupled plasma-atomic emission spectroscopy. The different Kp values of the gold conjugates (i.e., 13.98, 2.11, and 0.036 for GNP350, GNP550, and GNP750, respectively) resulted in different conjugate localization within liposomes, as observed by transmission electron microscopy. In addition, the cellular uptake of hybrid liposomes co-encapsulating gold conjugates and Nile red was evaluated using intracellular fluorescence intensity. The results indicated that precise GNP localization in the hydrophilic or hydrophobic liposome cavity could be achieved by regulating the GNP oil-water partition coefficient via surface modification; such localization could further affect the properties and functions of hybrid liposomes, including their cellular uptake profiles. This study furthers the understanding not only of the interaction between liposomes and inorganic nanoparticles but also of adjusting liposome-gold hybrid nanostructure properties via the surface chemistry of gold materials.

  18. Bayesian approach to estimate AUC, partition coefficient and drug targeting index for studies with serial sacrifice design.

    Wang, Tianli; Baron, Kyle; Zhong, Wei; Brundage, Richard; Elmquist, William


    The current study presents a Bayesian approach to non-compartmental analysis (NCA), which provides the accurate and precise estimate of AUC 0 (∞) and any AUC 0 (∞) -based NCA parameter or derivation. In order to assess the performance of the proposed method, 1,000 simulated datasets were generated in different scenarios. A Bayesian method was used to estimate the tissue and plasma AUC 0 (∞) s and the tissue-to-plasma AUC 0 (∞) ratio. The posterior medians and the coverage of 95% credible intervals for the true parameter values were examined. The method was applied to laboratory data from a mice brain distribution study with serial sacrifice design for illustration. Bayesian NCA approach is accurate and precise in point estimation of the AUC 0 (∞) and the partition coefficient under a serial sacrifice design. It also provides a consistently good variance estimate, even considering the variability of the data and the physiological structure of the pharmacokinetic model. The application in the case study obtained a physiologically reasonable posterior distribution of AUC, with a posterior median close to the value estimated by classic Bailer-type methods. This Bayesian NCA approach for sparse data analysis provides statistical inference on the variability of AUC 0 (∞) -based parameters such as partition coefficient and drug targeting index, so that the comparison of these parameters following destructive sampling becomes statistically feasible.

  19. [Determination of partition coefficient of dissolved gases in transformer oil using phase ratio variation method and static headspace gas chromatography].

    Zhao, Jinghong; Wang, Hailong; Liu, Wenmin; Zhou, Yansheng; Guan, Yafeng


    The partition coefficients of dissolved gases in transformer oil were determined using a phase ratio variation method and static headspace gas chromatography (GC). A pressure balancing and gas volume-metering device was connected to the vent of a sample loop on a six-port injection valve of the GC. The gas phase sample from the headspace vial of 25 mL was transferred to an 80 microL sample-loop through a fused silica capillary of 0.53 mm i.d., and then separated and determined quantitatively by GC. A 2 m x 1 mm i.d. GDX502 micro-packed column was used for the separation. Five different gas-liquid volume ratios in the headspace vials were measured at different equilibrium concentrations. The partition coefficients of hydrocarbon gases including methane, acetylene, ethylene, ethane and propane dissolved in transformer oil were determined by using linear regression analysis at 20 degrees C and 50 degrees C separately. The errors between the real values and regression values from experimental data were less than 4.14% except methane. Fundamental data for on-line measurement of dissolved gases in transformer oil are provided by GC.

  20. Development of TLSER model and QSAR model for predicting partition coefficients of hydrophobic organic chemicals between low density polyethylene film and water.

    Liu, Huihui; Wei, Mengbi; Yang, Xianhai; Yin, Cen; He, Xiao


    Partition coefficients are vital parameters for measuring accurately the chemicals concentrations by passive sampling devices. Given the wide use of low density polyethylene (LDPE) film in passive sampling, we developed a theoretical linear solvation energy relationship (TLSER) model and a quantitative structure-activity relationship (QSAR) model for the prediction of the partition coefficient of chemicals between LDPE and water (Kpew). For chemicals with the octanol-water partition coefficient (log Kow) coefficient (R(2)) and cross-validated coefficient (Q(2)). In order to further explore the theoretical mechanisms involved in the partition process, a QSAR model with four descriptors (MLOGP (Moriguchi octanol-water partition coeff.), P_VSA_s_3 (P_VSA-like on I-state, bin 3), Hy (hydrophilic factor) and NssO (number of atoms of type ssO)) was established, and statistical analysis indicated that the model had satisfactory goodness-of-fit, robustness and predictive ability. For chemicals with log KOW>8, a TLSER model with Vx and a QSAR model with MLOGP as descriptor were developed. This is the first paper to explore the models for highly hydrophobic chemicals. The applicability domain of the models, characterized by the Euclidean distance-based method and Williams plot, covered a large number of structurally diverse chemicals, which included nearly all the common hydrophobic organic compounds. Additionally, through mechanism interpretation, we explored the structural features those governing the partition behavior of chemicals between LDPE and water.

  1. Determination of the subcutaneous tissue to blood partition coefficient in patients with severe leg ischaemia by a double isotope washout technique

    Bjerre-Jepsen, K; Faris, I; Henriksen, O;


    Knowledge of the tissue to blood partition coefficient (lambda) is essential for calculation of the perfusion coefficient in a single tissue based on measurements of the washout of locally injected isotopes. No measurements of lambda for Xenon in subcutaneous tissue in the leg have been done...

  2. Determination of silicone rubber and low-density polyethylene diffusion and polymer/water partition coefficients for emerging contaminants.

    Pintado-Herrera, Marina G; Lara-Martín, Pablo A; González-Mazo, Eduardo; Allan, Ian J


    There is a growing interest in assessing the concentration and distribution of new nonregulated organic compounds (emerging contaminants) in the environment. The measurement of freely dissolved concentrations using conventional approaches is challenging because of the low concentrations that may be encountered and their temporally variable emissions. Absorption-based passive sampling enables the estimation of freely dissolved concentrations of hydrophobic contaminants of emerging concern in water. In the present study, calibration was undertaken for 2 polymers, low-density polyethylene (LDPE) and silicone rubber for 11 fragrances, 5 endocrine-disrupting compounds, 7 ultraviolet (UV) filters, and 8 organophosphate flame retardant compounds. Batch experiments were performed to estimate contaminant diffusion coefficients in the polymers (Dp ), which in general decreased with increasing molecular weight. The values for fragrances, endocrine-disrupting compounds, and UV filters were in ranges similar to those previously reported for polycyclic aromatic hydrocarbons, but were 1 order of magnitude lower for organophosphate flame retardant compounds. Silicone rubber had higher Dp values than LDPE and was therefore selected for further experiments to calculate polymer/water partition coefficients (KPW ). The authors observed a positive correlation between log KPW and log octanol/water partition coefficient values. Field testing of silicone rubber passive samplers was undertaken though exposure in the River Alna (Norway) for an exposure time of 21 d to estimate freely dissolved concentration. Some fragrances and UV filters were predominant over other emerging and regulated contaminants, at levels up to 1600 ng L(-1) for galaxolide and 448 ng L(-1) for octocrylene. Environ Toxicol Chem 2016;35:2162-2172. © 2016 SETAC.

  3. Partition Coefficients of Organic Molecules in Squalane and Water/Ethanol Mixtures by Molecular Dynamics Simulations

    Lundsgaard, Rasmus; Kontogeorgis, Georgios; Economou, Ioannis G.


    coefficient can be estimated for both a small hydrophilic and a hydrophobic organic molecules between squalane (used here to mimic low density poly ethylene) and water/ethanol solutes using thermodynamic integration to calculate the free energy of solvation. Molecular dynamics simulations are performed, using...

  4. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds.

    Wei, Wenjuan; Mandin, Corinne; Blanchard, Olivier; Mercier, Fabien; Pelletier, Maud; Le Bot, Barbara; Glorennec, Philippe; Ramalho, Olivier


    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25°C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R>0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6°C, while it increased by up to 750% when the indoor temperature increased from 15°C to 30°C.

  5. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds

    Wei, Wenjuan, E-mail: [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); Mandin, Corinne [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); Blanchard, Olivier [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Mercier, Fabien [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Pelletier, Maud [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Le Bot, Barbara [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); and others


    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25 °C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R > 0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6 °C, while it increased by up to 750% when the indoor temperature increased from 15 °C to 30 °C. - Highlights: • A theoretical relationship between K{sub p} and temperature was developed. • The relationship was based on the SVOC absorptive mechanism. • The temperature impact was quantified by a dimensionless analysis.

  6. A novel method for measuring the diffusion, partition and convective mass transfer coefficients of formaldehyde and VOC in building materials.

    Jianyin Xiong

    Full Text Available The diffusion coefficient (D(m and material/air partition coefficient (K are two key parameters characterizing the formaldehyde and volatile organic compounds (VOC sorption behavior in building materials. By virtue of the sorption process in airtight chamber, this paper proposes a novel method to measure the two key parameters, as well as the convective mass transfer coefficient (h(m. Compared to traditional methods, it has the following merits: (1 the K, D(m and h(m can be simultaneously obtained, thus is convenient to use; (2 it is time-saving, just one sorption process in airtight chamber is required; (3 the determination of h(m is based on the formaldehyde and VOC concentration data in the test chamber rather than the generally used empirical correlations obtained from the heat and mass transfer analogy, thus is more accurate and can be regarded as a significant improvement. The present method is applied to measure the three parameters by treating the experimental data in the literature, and good results are obtained, which validates the effectiveness of the method. Our new method also provides a potential pathway for measuring h(m of semi-volatile organic compounds (SVOC by using that of VOC.

  7. Evaluation of the use of partition coefficients and molecular surface properties as predictors of drug absorption: a provisional biopharmaceutical classification of the list of national essential medi

    NU Rahman


    Full Text Available Background and the purpose of the study: Partition coefficients (log D and log P and molecular surface area (PSA are potential predictors of the intestinal permeability of drugs. The aim of this investigation was to evaluate and compare these intestinal permeability indicators.   Methods: Aqueous solubility data were obtained from literature or calculated using ACD/Labs and ALOGPS. Permeability data were predicted based on log P, log D at pH 6.0 (log D6.0, and PSA.  Results: Metoprolol's log P, log D6.0 and a PSA of <65 Å correctly predicted 55.9%, 50.8% and 54.2% of permeability classes, respectively. Labetalol's log P, log D6.0, and PSA correctly predicted 54.2%, 64.4% and 61% of permeability classes, respectively. Log D6.0 correlated well (81% with Caco-2 permeability (Papp. Of the list of national essential medicines, 135 orally administered drugs were classified into biopharmaceutical classification system (BCS. Of these, 57 (42.2%, 28 (20.7%, 44 (32.6%, and 6 (4.4% were class I, II, III and IV respectively. Conclusion: Log D6.0 showed better prediction capability than log P. Metoprolol as permeability internal standard was more conservative than labetalol.

  8. Stochastic modeling of phosphorus transport in the Three Gorges Reservoir by incorporating variability associated with the phosphorus partition coefficient

    Huang, Lei; Fang, Hongwei; Xu, Xingya; He, Guojian; Zhang, Xuesong; Reible, Danny


    Phosphorus (P) fate and transport plays a crucial role in the ecology of rivers and reservoirs in which eutrophication is limited by P. A key uncertainty in models used to help manage P in such systems is the partitioning of P to suspended and bed sediments. By analyzing data from field and laboratory experiments, we stochastically characterize the variability of the partition coefficient (Kd) and derive spatio-temporal solutions for P transport in the Three Gorges Reservoir (TGR). We formulate a set of stochastic partial different equations (SPDEs) to simulate P transport by randomly sampling Kd from the measured distributions, to obtain statistical descriptions of the P concentration and retention in the TGR. The correspondence between predicted and observed P concentrations and P retention in the TGR combined with the ability to effectively characterize uncertainty suggests that a model that incorporates the observed variability can better describe P dynamics and more effectively serve as a tool for P management in the system. This study highlights the importance of considering parametric uncertainty in estimating uncertainty/variability associated with simulated P transport.

  9. Development and evaluation of predictive model for bovine serum albumin-water partition coefficients of neutral organic chemicals.

    Ma, Guangcai; Yuan, Quan; Yu, Haiying; Lin, Hongjun; Chen, Jianrong; Hong, Huachang


    The binding of organic chemicals to serum albumin can significantly reduce their unbound concentration in blood and affect their biological reactions. In this study, we developed a new QSAR model for bovine serum albumin (BSA) - water partition coefficients (KBSA/W) of neutral organic chemicals with large structural variance, logKBSA/W values covering 3.5 orders of magnitude (1.19-4.76). All chemical geometries were optimized by semi-empirical PM6 algorithm. Several quantum chemical parameters that reflect various intermolecular interactions as well as hydrophobicity were selected to develop QSAR model. The result indicates the regression model derived from logKow, the most positive net atomic charges on an atom, Connolly solvent excluded volume, polarizability, and Abraham acidity could explain the partitioning mechanism of organic chemicals between BSA and water. The simulated external validation and cross validation verifies the developed model has good statistical robustness and predictive ability, thus can be used to estimate the logKBSA/W values for chemicals in application domain, accordingly to provide basic data for the toxicity assessment of the chemicals.

  10. Development of polyparameter linear free energy relationship models for octanol-air partition coefficients of diverse chemicals.

    Jin, Xiaochen; Fu, Zhiqiang; Li, Xuehua; Chen, Jingwen


    The octanol-air partition coefficient (KOA) is a key parameter describing the partition behavior of organic chemicals between air and environmental organic phases. As the experimental determination of KOA is costly, time-consuming and sometimes limited by the availability of authentic chemical standards for the compounds to be determined, it becomes necessary to develop credible predictive models for KOA. In this study, a polyparameter linear free energy relationship (pp-LFER) model for predicting KOA at 298.15 K and a novel model incorporating pp-LFERs with temperature (pp-LFER-T model) were developed from 795 log KOA values for 367 chemicals at different temperatures (263.15-323.15 K), and were evaluated with the OECD guidelines on QSAR model validation and applicability domain description. Statistical results show that both models are well-fitted, robust and have good predictive capabilities. Particularly, the pp-LFER model shows a strong predictive ability for polyfluoroalkyl substances and organosilicon compounds, and the pp-LFER-T model maintains a high predictive accuracy within a wide temperature range (263.15-323.15 K).

  11. Evaluation of QSAR models for predicting the partition coefficient (log P) of chemicals under the REACH regulation.

    Cappelli, Claudia Ileana; Benfenati, Emilio; Cester, Josep


    The partition coefficient (log P) is a physicochemical parameter widely used in environmental and health sciences and is important in REACH and CLP regulations. In this regulatory context, the number of existing experimental data on log P is negligible compared to the number of chemicals for which it is necessary. There are many models to predict log P and we have selected a number of free programs to examine how they predict the log P of chemicals registered for REACH and to evaluate wheter they can be used in place of experimental data. Some results are good, especially if the information on the applicability domain of the models is considered, with R(2) values from 0.7 to 0.8 and root mean square error (RMSE) from 0.8 to 1.5.

  12. Relation between the solubility of proteins in aqueous solutions and the second virial coefficient of the solution

    Haas, C; Drenth, J; Wilson, WW


    Tn recent publications it was pointed out that there is a correlation between the observed values of the solubility of proteins in aqueous solutions and the second virial coefficient of the solution. In this paper we give a theoretical explanation of this relation. The derived theoretical expression

  13. Relation between the solubility of proteins in aqueous solutions and the second virial coefficient of the solution

    Haas, C; Drenth, J; Wilson, WW


    Tn recent publications it was pointed out that there is a correlation between the observed values of the solubility of proteins in aqueous solutions and the second virial coefficient of the solution. In this paper we give a theoretical explanation of this relation. The derived theoretical expression

  14. Phase Partitioning of Soluble Trace Gases with Size-Resolved Aerosols during the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) Campaign

    Young, A.; Keene, W. C.; Pszenny, A.; Sander, R.; Maben, J. R.; Warrick-Wriston, C.; Bearekman, R.


    During February and March 2011, size-resolved and bulk aerosol were sampled at 22 m above the surface over nominal 12-hour (daytime and nighttime) intervals from the Boulder Atmospheric Observatory tower (40.05 N, 105.01 W, 1584-m elevation). Samples were analyzed for major organic and inorganic ionic constituents by high performance ion chromatography (IC). Soluble trace gases (HCl, HNO3, NH3, HCOOH, and CH3COOH) were sampled in parallel over 2-hour intervals with tandem mist chambers and analyzed on site by IC. NH4+, NO3-, and SO42- were the major ionic components of aerosols (median values of 57.7, 34.5, and 7.3 nmol m-3 at STP, respectively, N = 45) with 86%, 82%, and 82%, respectively, associated with sub-μm size fractions. Cl- and Na+ were present at significant concentrations (median values of 6.8 and 6.6 nmol m-3, respectively) but were associated primarily with super-μm size fractions (75% and 78%, respectively). Median values (and ranges) for HCl, HNO3, and NH3 were 21 (Liquid water contents of size-resolved aerosols and activity coefficients for major ionic constituents were calculated with the Extended Aerosol Inorganic Model II and IV (E-AIM) based on the measured aerosol composition, RH, temperature, and pressure. Size-resolved aerosol pHs were inferred from the measured phase partitioning of HCl, HNO3, and NH3. Major controls of phase partitioning and associated chemical dynamics will be presented.

  15. The dependence of equilibrium partition coefficient of cesium and iodine between sodium pool and the inert cover gas on the concentration in the pool

    Miyahara, Shinya, E-mail: [FBR Plant Engineering Center, Japan Atomic Energy Agency, 1 Shiraki, Tsuruga, Fukui 919-1279 (Japan); Research Institute of Nuclear Engineering, University of Fukui, 1-3-9 Bunkyo, Fukui 910-8507 (Japan); Nishimura, Masahiro, E-mail: [O-arai Research and Development Center, Japan Atomic Energy Agency, 4002 Narita, Oarai, Ibaraki 311-1393 (Japan); Nakagiri, Toshio, E-mail: [FBR Plant Engineering Center, Japan Atomic Energy Agency, 1 Shiraki, Tsuruga, Fukui 919-1279 (Japan)


    Highlights: Black-Right-Pointing-Pointer We measured equilibrium partition coefficients of cesium and iodine between liquid sodium pool and the inert cover gas. Black-Right-Pointing-Pointer The obtained empirical equations were consistent with Castleman's theoretical equations. Black-Right-Pointing-Pointer The effect of cesium concentration upon the partition coefficients was consistent with the theoretical values. Black-Right-Pointing-Pointer That of iodine concentration was incompatible with the theoretical consideration due to the formation of Na{sub 2}I{sub 2} in the cover gas. - Abstract: Equilibrium partition coefficients were experimentally measured for volatile fission products of cesium and iodine between liquid sodium pool and the inert cover gas. In the experiments, the 'transpiration method' was utilized in which the saturation vapor of sodium with cesium and iodine vapor in an isothermal evaporation pot was transported by inert carrier gas and trapped by filters outside the pot. The objectives of the experiments are to: (a)obtain the equilibrium partition coefficients of cesium and iodine at high temperature between 600 and 850 Degree-Sign C and, (b)study the dependence of the partition coefficients upon the concentration in the sodium pool. From the results of previous work and this study, the following empirical equations between the partition coefficients of cesium and iodine and the sodium pool temperature could be obtained: logKd(Cs)=(2173)/T -1.0487(from450to850 Degree-Sign C), logKd(I)=(-215)/T -0.271(from450to850 Degree-Sign C). These equations are consistent with Castleman's theoretical equations. The partition coefficients of cesium measured at five different points of mole concentration in the pool were almost consistent with the theoretical values and decreased with the increase in the concentration. On the other hand, the measured partition coefficients of iodine increased with the increase in the concentration in the

  16. 黄芩甙在EOPO/盐双水相系统中的分配系数测定及关联%Measurement and Correlation of Partition Coefficients of Baicalin in EOPO/Salt Aqueous Two-Phase Systems

    李伟; 朱自强


    The partition coefficients of baicalin were measured in ethylene oxide and propylene oxide (EOPO)/salt aqueous two-phase systemsat 298.15K. It was found that most of baicalin partitioned into EOPO-rich phase. The partition coefficients of baicalin varied from 10 to 120.The effect of various factors, including tie-line length, salt composition, molecular weight of EOPO, and solution pH, on the partition behaviorwas investigated in EOPO/salt systems. Furthermore the partition coefficients of baicalin were correlated using the modified Diamond-Hsumodel. Good agreement with experimental data is obtained. The average relative deviations are less than 5.0%.

  17. Estimating the octanol/water partition coefficient for aliphatic organic compounds using semi-empirical electrotopological index.

    Souza, Erica Silva; Zaramello, Laize; Kuhnen, Carlos Alberto; Junkes, Berenice da Silva; Yunes, Rosendo Augusto; Heinzen, Vilma Edite Fonseca


    A new possibility for estimating the octanol/water coefficient (log P) was investigated using only one descriptor, the semi-empirical electrotopological index (I(SET)). The predictability of four octanol/water partition coefficient (log P) calculation models was compared using a set of 131 aliphatic organic compounds from five different classes. Log P values were calculated employing atomic-contribution methods, as in the Ghose/Crippen approach and its later refinement, AlogP; using fragmental methods through the ClogP method; and employing an approach considering the whole molecule using topological indices with the MlogP method. The efficiency and the applicability of the I(SET) in terms of calculating log P were demonstrated through good statistical quality (r > 0.99; s < 0.18), high internal stability and good predictive ability for an external group of compounds in the same order as the widely used models based on the fragmental method, ClogP, and the atomic contribution method, AlogP, which are among the most used methods of predicting log P.

  18. Experimental and QSPR Studies on n-Octanol/water Partition Coefficient(lgKow) of Substituted Aniline


    The n-octanol/water partition coefficients (lgKow) of 18 substituted anilines were determined at 25 ℃ by shake-flask method. The geometrical optimization of substituted anilines has been performed at B3LYP/6-311G** level with Gaussian98 program, and the molecular surface areas of substituted anilines were calculated using ChemOffice 2004 program. The calculated structural parameters of substituted anilines were used as theoretical descriptors and the two-parameter (molecular surface area (MA) and the energy of the highest occupied molecular orbital (EHOMO)) quantitative structure-property relationship (QSPR) model of lgKow for substituted aniline with molecular structural parameters was developed by multi-linear regression method. The regression coefficient square (r2) is 0.990 and the standard deviation SE 0.109. The model was validated by variance inflation factors (VIF) and t-test, and the results show that there exists small self-correlation between variables of the model with perfect stability. The model gives results in good qualitative agreement with experimental data. At last, the model was applied to predict lgKow values of five substituted anilines whose lgKow values have not been determined experimentally.

  19. Plutonium partitioning in three-phase systems with water, colloidal particles, and granites: new insights into distribution coefficients.

    Xie, Jinchuan; Lin, Jianfeng; Zhou, Xiaohua; Li, Mei; Zhou, Guoqing


    The traditional sorption experiments commonly treated the colloid-associated species of low-solubility contaminants as immobile species resulted from the centrifugation or ultrafiltration, and then solid/liquid distribution coefficients (Ks/d) were determined. This may lead to significantly underestimated mobility of the actinides in subsurface environments. Accordingly, we defined a new distribution coefficient (Ks/d+c) to more adequately describe the mobile characteristics of colloidal species. The results show that under alkaline aqueous conditions the traditional Ks/d was 2-3 orders of magnitude larger than the Ks/d+c involving the colloidal species of (239)Pu. The colloid/liquid distribution coefficients Kc/d≫0 (∼10(6)mL/g) revealed strong competition of the colloidal granite particles with the granite grains for Pu. The distribution percentages of Pu in the three-phase systems, depending on various conditions such as particle concentrations, Na(+) concentrations, pH and time, were determined. Moreover, we developed the thermodynamic and kinetic complexation models to explore the interaction of Pu with the particle surfaces.

  20. Thermal analysis of pad-on-disc contact under tribological solicitations: a coupled numerical-experimental approach to identify surface temperatures and flow partition coefficient

    Sellami, Amira; Kchaou, Mohamed; Elleuch, Riadh; Desplanques, Yannick


    Aiming to provide a better understanding of thermal phenomena occurring in a sliding contact under tribological solicitation, a numerical model of pad-on-disc tribometer has been proposed. This study deals with an inverse problem concerning the identification of the heat exchange coefficient "h". The method used allows the sequential estimation of the thermal boundary conditions by minimizing an error function between numerical and experimental temperature values. Coupled with the identification of the heat flux partition coefficient, the proposed model is validated.

  1. Adsorption of polycyclic aromatic hydrocarbons (PAHs) on Rhizopus oryzae cell walls: application of cosolvent models for validating the cell wall-water partition coefficient.

    Ma, Bin; Xu, Minmin; Wang, Jiaojiao; Chen, Huaihai; He, Yan; Wu, Laosheng; Wang, Haizhen; Xu, Jianming


    The cell wall-cosolvent partition coefficients (Km) of polycyclic aromatic hydrocarbons (PAHs) were determined for Rhizopus oryzae cell walls by controlling the volume fraction of methanol (f) ranging from 0.1 to 0.5. Five cosolvent models were employed for extrapolating the cell wall-water partition coefficients (Kw) in pure water. The extrapolated Kw values of four PAHs on R. oryzae cell walls were ranged from 2.9 to 5.1. Comparison of various Kw values of pyrene generated from extrapolation and the QSPR model, together with predicted different (PD), mean percentage deviations (MPD), and root mean square errors (RSE), revealed that the performance of the LL and Bayesian models were the best among all five tested cosolvent models. This study suggests that R. oryzae cell walls play an important role in the partitioning of PAHs during bioremediation because of the high Kw of fungal cell walls.

  2. Background vapor from six ionic liquids and the partition coefficients and limits of detection for 10 different analytes in those ionic liquids measured using headspace gas chromatography.

    Von Wald, Grant; Albers, David; Cortes, Hernan; McCabe, Terry


    The concentration and identity of the compounds detected in the vapor above six ionic liquids by headspace gas chromatography (HS-GC) at 100 degrees C are reported. In addition, the partition coefficients for 10 different compounds in these ionic liquids and limits of detection were measured. These results provide quantitative guidance for the application of ionic liquids for HS-GC.

  3. Absorption of hydrophobic compounds into the poly(dimethylsiloxane) coating of solid-phase microextraction fibers : high partition coefficients and fluorescence microscopy images

    Mayer, P.; Vaes, W.H.J.; Hermens, J.L.M.


    The use of solid-phase microextraction with poly(dimethylsiloxane) (PDMS)-coated glass fibers for the extraction and analysis of hydrophobic organic analytes is increasing. The literature on this topic is characterized by large discrepancies in partition coefficients and an uncertainty of whether hi

  4. Temperature-dependent solubilities and mean ionic activity coefficients of alkali halides in water from molecular dynamics simulations

    Mester, Zoltan; Panagiotopoulos, Athanassios Z.


    The mean ionic activity coefficients of aqueous KCl, NaF, NaI, and NaCl solutions of varying concentrations have been obtained from molecular dynamics simulations following a recently developed methodology based on gradual insertions of salt molecules [Z. Mester and A. Z. Panagiotopoulos, J. Chem. Phys. 142, 044507 (2015)]. The non-polarizable ion models of Weerasinghe and Smith [J. Chem. Phys. 119, 11342 (2003)], Gee et al. [J. Chem. Theory Comput. 7, 1369 (2011)], Reiser et al. [J. Chem. Phys. 140, 044504 (2014)], and Joung and Cheatham [J. Phys. Chem. B 112, 9020 (2008)] were used along with the extended simple point charge (SPC/E) water model [Berendsen et al., J. Phys. Chem. 91, 6269 (1987)] in the simulations. In addition to the chemical potentials in solution used to obtain the activity coefficients, we also calculated the chemical potentials of salt crystals and used them to obtain the solubility of these alkali halide models in SPC/E water. The models of Weerasinghe and Smith [J. Chem. Phys. 119, 11342 (2003)] and Gee et al. [J. Chem. Theory Comput. 7, 1369 (2011)] provide excellent predictions of the mean ionic activity coefficients at 298.15 K and 1 bar, but significantly underpredict or overpredict the solubilities. The other two models generally predicted the mean ionic activity coefficients only qualitatively. With the exception of NaF for which the solubility is significantly overpredicted, the model of Joung and Cheatham predicts salt solubilities that are approximately 40%-60% of the experimental values. The models of Reiser et al. [J. Chem. Phys. 140, 044504 (2014)] make good predictions for the NaCl and NaI solubilities, but significantly underpredict the solubilities for KCl and NaF. We also tested the transferability of the models to temperatures much higher than were used to parametrize them by performing simulations for NaCl at 373.15 K and 1 bar, and at 473.15 K and 15.5 bar. All models overpredict the drop in the values of mean ionic

  5. QSPR models for predicting generator-column-derived octanol/water and octanol/air partition coefficients of polychlorinated biphenyls.

    Yuan, Jintao; Yu, Shuling; Zhang, Ting; Yuan, Xuejie; Cao, Yunyuan; Yu, Xingchen; Yang, Xuan; Yao, Wu


    Octanol/water (K(OW)) and octanol/air (K(OA)) partition coefficients are two important physicochemical properties of organic substances. In current practice, K(OW) and K(OA) values of some polychlorinated biphenyls (PCBs) are measured using generator column method. Quantitative structure-property relationship (QSPR) models can serve as a valuable alternative method of replacing or reducing experimental steps in the determination of K(OW) and K(OA). In this paper, two different methods, i.e., multiple linear regression based on dragon descriptors and hologram quantitative structure-activity relationship, were used to predict generator-column-derived log K(OW) and log K(OA) values of PCBs. The predictive ability of the developed models was validated using a test set, and the performances of all generated models were compared with those of three previously reported models. All results indicated that the proposed models were robust and satisfactory and can thus be used as alternative models for the rapid assessment of the K(OW) and K(OA) of PCBs.

  6. QSAR models for predicting octanol/water and organic carbon/water partition coefficients of polychlorinated biphenyls.

    Yu, S; Gao, S; Gan, Y; Zhang, Y; Ruan, X; Wang, Y; Yang, L; Shi, J


    Quantitative structure-property relationship modelling can be a valuable alternative method to replace or reduce experimental testing. In particular, some endpoints such as octanol-water (KOW) and organic carbon-water (KOC) partition coefficients of polychlorinated biphenyls (PCBs) are easier to predict and various models have been already developed. In this paper, two different methods, which are multiple linear regression based on the descriptors generated using Dragon software and hologram quantitative structure-activity relationships, were employed to predict suspended particulate matter (SPM) derived log KOC and generator column, shake flask and slow stirring method derived log KOW values of 209 PCBs. The predictive ability of the derived models was validated using a test set. The performances of all these models were compared with EPI Suite™ software. The results indicated that the proposed models were robust and satisfactory, and could provide feasible and promising tools for the rapid assessment of the SPM derived log KOC and generator column, shake flask and slow stirring method derived log KOW values of PCBs.

  7. Partition coefficients for iron between plagioclase and basalt as a function of oxygen fugacity - Implications for Archean and lunar anorthosites

    Phinney, W. C.


    As a prelude to determinations of the content of total iron as FeO(T) in melts in equilibrium with calcic anorthosites, the partition coefficients (Ds) for FeO(T) between calcic plagioclase and basaltic melt were determined, as a function of oxygen fugacity (f(O2)), for a basaltic composition that occurs as matrices for plagioclase megacrysts. Results showed that, at the liquidus conditions, the value of D for FeO(T) between calcic plagioclase and tholeiitic basalt changed little (from 0.030 to 0.044) between the very low f(O2) of the iron-wustite buffer and that of the quartz-fayalite-magnetite (QFM) buffer. At fugacities above QFM, the value for D increased rapidly to 0.14 at the magnetite-hematite buffer and to 0.33 in air. The increase in D results from the fact that, at f(O2) below QFM, nearly all of the Fe is in the Fe(2+) state; above QFM, the Fe(3+)/Fe(2+) ratio in the melt increases rapidly, causing more Fe to enter the plagioclase which accepts Fe(3+) more readily than Fe(2+).

  8. Removal of dissolved organic carbon by aquifer material: Correlations between column parameters, sorption isotherms and octanol-water partition coefficient.

    Pradhan, Snigdhendubala; Boernick, Hilmar; Kumar, Pradeep; Mehrotra, Indu


    The correlation between octanol-water partition coefficient (KOW) and the transport of aqueous samples containing single organic compound is well documented. The concept of the KOW of river water containing the mixture of organics was evolved by Pradhan et al. (2015). The present study aims at determining the KOW and sorption parameters of synthetic aqueous samples and river water to finding out the correlation, if any. The laboratory scale columns packed with aquifer materials were fed with synthetic and river water samples. Under the operating conditions, the compounds in the samples did not separate, and all the samples that contain more than one organic compound yielded a single breakthrough curve. Breakthrough curves simulated from sorption isotherms were compared with those from the column runs. The sorption parameters such as retardation factor (Rf), height of mass transfer zone (HMTZ), rate of mass transfer zone (RMTZ), breakpoint column capacity (qb) and maximum column capacity (qx) estimated from column runs, sorption isotherms and models developed by Yoon-Nelson, Bohart-Adam and Thomas were in agreement. The empirical correlations were found between the KOW and sorption parameters. The transport of the organics measured as dissolved organic carbon (DOC) through the aquifer can be predicted from the KOW of the river water and other water samples. The novelty of the study is to measure KOW and to envisage the fate of the DOC of the river water, particularly during riverbank filtration. Statistical analysis of the results revealed a fair agreement between the observed and computed values.

  9. Enhanced flushing of polychlorinated biphenyls contaminated sands using surfactant foam: effect of partition coefficient and sweep efficiency.

    Wang, Hao; Chen, Jiajun


    Foam flushing is an in situ soil remediation technology based on the traditional surfactant flushing method. The contribution of mobility control to contaminant removal by foam is helpful for improving this technology. Foam flushing of polychlorinated biphenyl (PCB)-contaminated unconsolidated media was performed to evaluate the effect of the partition coefficient (PC) and sweep efficiency (SE) on PCB removal. Column flushing with surfactant solution and foam with different types and concentrations of surfactant was carried out for PCB removal. Two types of quartz sand were investigated to evaluate the Jamin effect on the SE value of the washing agent. The results demonstrate that a small PC value and large SE value are necessary to achieve high PCB removal for foam flushing. Compared with solution flushing, the introduction of foam can effectively control the mobility of the washing agent. Similar to solution flushing, solubilization is a key factor which dominates the removal of PCBs in foam flushing. In addition, the SE value and PCB removal by foam flushing is less affected by particle size. Therefore, foam flushing was proved to be more effective in porous media with low hydraulic conductivity and high porosity. An integrated flushing with water, surfactant solution and foam was performed and the results prove that this technology successfully combines the advantages of solution solubilization and mobility control by foam, and thus further increases the remediation efficiency of PCBs to 94.7% for coarse sand.

  10. Enhanced flushing of polychlorinated biphenyls contaminated sands using surfactant foam: Effect of partition coefficient and sweep efficiency

    Hao Wang; Jiajun Chen


    Foam flushing is an in situ soil remediation technology based on the traditional surfactant flushing method.The contribution of mobility control to contaminant removal by foam is helpful for improving this technology.Foam flushing of polychlorinated biphenyl (PCB)-contaminated unconsolidated media was performed to evaluate the effect of the partition coefficient (PC) and sweep efficiency (SE) on PCB removal.Column flushing with surfactant solution and foam with different types and concentrations of surfactant was carried out for PCB removal.Two types of quartz sand were investigated to evaluate the Jamin effect on the SE value of the washing agent.The results demonstrate that a small PC value and large SE value are necessary to achieve high PCB removal for foam flushing.Compared with solution flushing,the introduction of foam can effectively control the mobility of the washing agent.Similar to solution flushing,solubilization is a key factor which dominates the removal of PCBs in foam flushing.In addition,the SE value and PCB removal by foam flushing is less affected by particle size.Therefore,foam flushing was proved to be more effective in porous media with low hydraulic conductivity and high porosity.An integrated flushing with water,surfactant solution and foam was performed and the results prove that this technology successfully combines the advantages of solution solubilization and mobility control by foam,and thus further increases the remediation efficiency of PCBs to 94.7% for coarse sand.

  11. Studies of n-Octanol/water Partition Coefficients (IgKow) for Organophosphate Compounds by Density Functional Theory

    LIU Hong-Xia; WANG Zun-Yao; ZHAI Zhi-Cai; LIU Hong-Yan; WANG Lian-Sheng


    Optimized calculation of 35 dialkyl phenyl phosphate compounds (OPs) was carried out at the B3LYP/6-31G* level in Gaussian 98 program. Based on the theoretical linear solvation energy relationship (TLSER) model, the obtained parameters were taken as theoretical descriptors to establish the novel QSPR model for predicting n-octanol/water partition coefficients (IgKow) of OPs. The new model achieved in this work contains three variables, i.e., molecular volume (Vm),dipole moment of the molecules (μ) and enthalpy (H0). For this model, R2 = 0.9167 and SD = 0.31 at large t values. In addition, the variation inflation factors (VIF) of variables are all close to 1.0,suggesting high accuracy of the predicting model. And the results of cross-validation test (q2 =0.8993) and method validation also showed the model of this study exhibited optimum stability and better predictive power than that from semi-empirical method. The model achieved can be used to predict lgKow of congeneric compounds.

  12. Air-water partition coefficients for a suite of polycyclic aromatic and other C10 through C20 unsaturated hydrocarbons.

    Rayne, Sierra; Forest, Kaya


    The air-water partition coefficients (Kaw) for 86 large polycyclic aromatic hydrocarbons and their unsaturated relatives were estimated using high-level G4(MP2) gas and aqueous phase calculations with the SMD, IEFPCM-UFF, and CPCM solvation models. An extensive method validation effort was undertaken which involved confirming that, via comparisons to experimental enthalpies of formation, gas-phase energies at the G4(MP2) level for the compounds of interest were at or near thermochemical accuracy. Investigations of the three solvation models using a range of neutral and ionic compounds suggested that while no clear preferential solvation model could be chosen in advance for accurate Kaw estimates of the target compounds, the employment of increasingly higher levels of theory would result in lower Kaw errors. Subsequent calculations on the polycyclic aromatic and unsaturated hydrocarbons at the G4(MP2) level revealed excellent agreement for the IEFPCM-UFF and CPCM models against limited available experimental data. The IEFPCM-UFF-G4(MP2) and CPCM-G4(MP2) solvation energy calculation approaches are anticipated to give Kaw estimates within typical experimental ranges, each having general Kaw errors of less than 0.5 log10 units. When applied to other large organic compounds, the method should allow development of a broad and reliable Kaw database for multimedia environmental modeling efforts on various contaminants.

  13. New Linear Partitioning Models based on Experimental Water – Supercritical CO2 Partitioning Data of Selected Organic Compounds

    Burant, Aniela S.; Thompson, Christopher J.; Lowry, Gregory; Karamalidis, Athanasios


    Partitioning coefficients of organic compounds between water and supercritical CO2 (sc-CO2) are necessary to assess the risk of migration of these chemicals from subsurface CO2 storage sites. Despite the large number of potential organic contaminants, the current data set of published water-sc-CO2 partitioning coefficients is very limited. Here, the partitioning coefficients of thiophene, pyrrole, and anisole were measured in situ over a range of temperatures and pressures using a novel pressurized batch reactor system with dual spectroscopic detectors: a near infrared spectrometer for measuring the organic analyte in the CO2 phase, and a UV detector for quantifying the analyte in the aqueous phase. Our measured partitioning coefficients followed expected trends based on volatility and aqueous solubility. The partitioning coefficients and literature data were then used to update a published poly-parameter linear free energy relationship and to develop five new linear free energy relationships for predicting water-sc-CO2 partitioning coefficients. Four of the models targeted a single class of organic compounds. Unlike models that utilize Abraham solvation parameters, the new relationships use vapor pressure and aqueous solubility of the organic compound at 25 °C and CO2 density to predict partitioning coefficients over a range of temperature and pressure conditions. The compound class models provide better estimates of partitioning behavior for compounds in that class than the model built for the entire dataset.

  14. The partitioning behavior of persistent toxicant organic contaminants in eutrophic sediments: Coefficients and effects of fluorescent organic matter and particle size.

    He, Wei; Yang, Chen; Liu, Wenxiu; He, Qishuang; Wang, Qingmei; Li, Yilong; Kong, Xiangzhen; Lan, Xinyu; Xu, Fuliu


    In the shallow lakes, the partitioning of organic contaminants into the water phase from the solid phase might pose a potential hazard to both benthic and planktonic organisms, which would further damage aquatic ecosystems. This study determined the concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and phthalate esters (PAEs) in both the sediment and the pore water from Lake Chaohu and calculated the sediment - pore water partition coefficient (KD) and the organic carbon normalized sediment - pore water partition coefficient (KOC), and explored the effects of particle size, organic matter content, and parallel factor fluorescent organic matter (PARAFAC-FOM) on KD. The results showed that log KD values of PAHs (2.61-3.94) and OCPs (1.75-3.05) were significantly lower than that of PAEs (4.13-5.05) (p  PAHs (4.61-5.86) > OCPs (3.62-4.97). A modified MCI model can predict KOC values in a range of log 1.5 at a higher frequency, especially for PAEs. The significantly positive correlation between KOC and the octanol - water partition coefficient (KOW) were observed for PAHs and OCPs. However, significant correlation was found for PAEs only when excluding PAEs with lower KOW. Sediments with smaller particle sizes (clay and silt) and their organic matter would affect distributions of PAHs and OCPs between the sediment and the pore water. Protein-like fluorescent organic matter (C2) was associated with the KD of PAEs. Furthermore, the partitioning of PARAFAC-FOM between the sediment and the pore water could potentially affect the distribution of organic pollutants. The partitioning mechanism of PAEs between the sediment and the pore water might be different from that of PAHs and OCPs, as indicated by their associations with influencing factors and KOW.

  15. Uranium partition coefficients (Kd) in forest surface soil reveal long equilibrium times and vary by site and soil size fraction.

    Whicker, Jeffrey J; Pinder, John E; Ibrahim, Shawki A; Stone, James M; Breshears, David D; Baker, Kristine N


    The environmental mobility of newly deposited radionuclides in surface soil is driven by complex biogeochemical relationships, which have significant impacts on transport pathways. The partition coefficient (Kd) is useful for characterizing the soil-solution exchange kinetics and is an important factor for predicting relative amounts of a radionuclide transported to groundwater compared to that remaining on soil surfaces and thus available for transport through erosion processes. Measurements of Kd for 238U are particularly useful because of the extensive use of 238U in military applications and associated testing, such as done at Los Alamos National Laboratory (LANL). Site-specific measurements of Kd for 238U are needed because Kd is highly dependent on local soil conditions and also on the fine soil fraction because 238U concentrates onto smaller soil particles, such as clays and soil organic material, which are most susceptible to wind erosion and contribute to inhalation exposure in off-site populations. We measured Kd for uranium in soils from two neighboring semiarid forest sites at LANL using a U.S. Environmental Protection Agency (EPA)-based protocol for both whole soil and the fine soil fraction (diametersKd values, which are those specified in the EPA protocol, ranged from 276-508 mL g-1 for whole soil and from 615-2249 mL g-1 for the fine soil fraction. Unexpectedly, the 30-d Kd values, measured to test for soil-solution exchange equilibrium, were more than two times the 7-d values. Rates of adsorption of 238U to soil from solution were derived using a 2-component (FAST and SLOW) exponential model. We found significant differences in Kd values among LANL sampling sites, between whole and fine soils, and between 7-d and 30-d Kd measurements. The significant variation in soil-solution exchange kinetics among the soils and soil sizes promotes the use of site-specific data for estimates of environmental transport rates and suggests possible differences in

  16. A new high-throughput method utilizing porous silica-based nano-composites for the determination of partition coefficients of drug candidates.

    Yu, Chih H; Tam, Kin; Tsang, Shik C


    We show that highly porous silica-based nanoparticles prepared via micro-emulsion and sol-gel techniques are stable colloids in aqueous solution. By incorporating a magnetic core into the porous silica nano-composite, it is found that the material can be rapidly separated (precipitated) upon exposure to an external magnetic field. Alternatively, the porous silica nanoparticles without magnetic cores can be equally separated from solution by applying a high-speed centrifugation. Using these silica-based nanostructures a new high-throughput method for the determination of partition coefficient for water/n-octanol is hereby described. First, a tiny quantity of n-octanol phase is pre-absorbed in the porous silica nano-composite colloids, which allows an establishment of interface at nano-scale between the adsorbed n-octanol with the bulk aqueous phase. Organic compounds added to the mixture can therefore undergo a rapid partition between the two phases. The concentration of drug compound in the supernatant in a small vial can be determined by UV-visible absorption spectroscopy. With the adaptation of a robotic liquid handler, a high-throughput technology for the determination of partition coefficients of drug candidates can be employed for drug screening in the industry based on these nano-separation skills. The experimental results clearly suggest that this new method can provide partition coefficient values of potential drug candidates comparable to the conventional shake-flask method but requires much shorter analytical time and lesser quantity of chemicals.

  17. GEMAS: prediction of solid-solution phase partitioning coefficients (Kd) for oxoanions and boric acid in soils using mid-infrared diffuse reflectance spectroscopy.

    Janik, Leslie J; Forrester, Sean T; Soriano-Disla, José M; Kirby, Jason K; McLaughlin, Michael J; Reimann, Clemens


    The authors' aim was to develop rapid and inexpensive regression models for the prediction of partitioning coefficients (Kd), defined as the ratio of the total or surface-bound metal/metalloid concentration of the solid phase to the total concentration in the solution phase. Values of Kd were measured for boric acid (B[OH]3(0)) and selected added soluble oxoanions: molybdate (MoO4(2-)), antimonate (Sb[OH](6-)), selenate (SeO4(2-)), tellurate (TeO4(2-)) and vanadate (VO4(3-)). Models were developed using approximately 500 spectrally representative soils of the Geochemical Mapping of Agricultural Soils of Europe (GEMAS) program. These calibration soils represented the major properties of the entire 4813 soils of the GEMAS project. Multiple linear regression (MLR) from soil properties, partial least-squares regression (PLSR) using mid-infrared diffuse reflectance Fourier-transformed (DRIFT) spectra, and models using DRIFT spectra plus analytical pH values (DRIFT + pH), were compared with predicted log K(d + 1) values. Apart from selenate (R(2)  = 0.43), the DRIFT + pH calibrations resulted in marginally better models to predict log K(d + 1) values (R(2)  = 0.62-0.79), compared with those from PSLR-DRIFT (R(2)  = 0.61-0.72) and MLR (R(2)  = 0.54-0.79). The DRIFT + pH calibrations were applied to the prediction of log K(d + 1) values in the remaining 4313 soils. An example map of predicted log K(d + 1) values for added soluble MoO4(2-) in soils across Europe is presented. The DRIFT + pH PLSR models provided a rapid and inexpensive tool to assess the risk of mobility and potential availability of boric acid and selected oxoanions in European soils. For these models to be used in the prediction of log K(d + 1) values in soils globally, additional research will be needed to determine if soil variability is accounted on the calibration.

  18. A Colorful Laboratory Investigation of Hydrophobic Interactions, the Partition Coefficient, Gibbs Energy of Transfer, and the Effect of Hofmeister Salts

    McCain, Daniel F.; Allgood, Ottie E.; Cox, Jacob T.; Falconi, Audrey E.; Kim, Michael J.; Shih, Wei-Yu


    Only a few pedagogical experiments have been published dealing specifically with the hydrophobic interaction though it plays a central role in biochemistry. A set of experiments is presented in which students partition a variety of colorful indicator dyes in biphasic water/organic solvent mixtures. Students monitor the partitioning visually and…

  19. Quantitative structure-property relationship modeling of water-to-wet butyl acetate partition coefficient of 76 organic solutes using multiple linear regression and artificial neural network.

    Dashtbozorgi, Zahra; Golmohammadi, Hassan


    The main aim of this study was the development of a quantitative structure-property relationship method using an artificial neural network (ANN) for predicting the water-to-wet butyl acetate partition coefficients of organic solutes. As a first step, a genetic algorithm-multiple linear regression model was developed; the descriptors appearing in this model were considered as inputs for the ANN. These descriptors are principal moment of inertia C (I(C)), area-weighted surface charge of hydrogen-bonding donor atoms (HACA-2), Kier and Hall index (order 2) ((2)χ), Balaban index (J), minimum bond order of a C atom (P(C)) and relative negative-charged SA (RNCS). Then a 6-4-1 neural network was generated for the prediction of water-to-wet butyl acetate partition coefficients of 76 organic solutes. By comparing the results obtained from multiple linear regression and ANN models, it can be seen that statistical parameters (Fisher ratio, correlation coefficient and standard error) of the ANN model are better than that regression model, which indicates that nonlinear model can simulate the relationship between the structural descriptors and the partition coefficients of the investigated molecules more accurately.

  20. Solid/liquid partition coefficients (Kd) for selected soils and sediments at Forsmark and Laxemar-Simpevarp

    Sheppard, Steve; Long, Jeff; Sanipelli, Barb (ECOMatters Inc., Pinawa (Canada)); Sohlenius, Gustav (Geological Survey of Sweden (SGU), Uppsala (Sweden))


    Soil and sediment solid/liquid partition coefficients (Kd) are used to indicate the relative mobility of radionuclides and elements of concern from nuclear fuel waste, as well as from other sources. The Kd data are inherently extremely variable, but also vary systematically with key environmental attributes. For soil Kd, the key variables are pH, clay content and organic carbon content. For sediment Kd, water type (freshwater versus marine) and sediment type (benthic versus suspended) are important. This report summarized Kd data for soils and sediments computed from indigenous stable element concentrations measured at the Forsmark and Laxemar-Simpevarp sites. These were then compared to several literature sources of Kd data for Ce, Cl, Co, Cr, Cs, Fe, Ho, I, La, Mn, Mo, Nb, Nd, Ni, Np, Pa, Pb, Pu, Ra, Sb, Se, Sm, Sn, Sr, Tc, Th, Tm, U and Yb. The Kd data computed from indigenous stable element concentrations may be especially relevant for assessment of long-lived radionuclides from deep disposal of waste, because the long time frame for the potential releases is more consistent with the steady state measured using indigenous stable elements. For almost every one of these elements in soils, a statistically meaningful regression equation was developed to allow estimation of Kd for any soil given a modest amount of information about the soil. Nonetheless, the median residual geometric standard deviation (GSD) was 4.3-fold, implying confidence bounds of about 18-fold above and below the best estimate Kd. For sediment, the values are categorised simply by water type and sediment type. The median GSD for sediment Kd as measured at the Forsmark and Laxemar-Simpevarp sites was 2.5-fold, but the median GSD among literature values was as high as 8.6-fold. Clearly, there remains considerable uncertainty in Kd values, and it is important to account for this in assessment applications

  1. Determination of Unbound Partition Coefficient and in Vitro-in Vivo Extrapolation for SLC13A Transporter-Mediated Uptake.

    Riccardi, Keith; Li, Zhenhong; Brown, Janice A; Gorgoglione, Matthew F; Niosi, Mark; Gosset, James; Huard, Kim; Erion, Derek M; Di, Li


    Unbound partition coefficient (Kpuu) is important to an understanding of the asymmetric free drug distribution of a compound between cells and medium in vitro, as well as between tissue and plasma in vivo, especially for transporter-mediated processes. Kpuu was determined for a set of compounds from the SLC13A family that are inhibitors and substrates of transporters in hepatocytes and transporter-transfected cell lines. Enantioselectivity was observed, with (R)-enantiomers achieving much higher Kpuu (>4) than the (S)-enantiomers (<1) in human hepatocytes and SLC13A5-transfected human embryonic 293 cells. The intracellular free drug concentration correlated directly with in vitro pharmacological activity rather than the nominal concentration in the assay because of the high Kpuu mediated by SLC13A5 transporter uptake. Delivery of the diacid PF-06649298 directly or via hydrolysis of the ethyl ester prodrug PF-06757303 resulted in quite different Kpuu values in human hepatocytes (Kpuu of 3 for diacid versus 59 for prodrug), which was successfully modeled on the basis of passive diffusion, active uptake, and conversion rate from ester to diacid using a compartmental model. Kpuu values changed with drug concentrations; lower values were observed at higher concentrations possibly owing to a saturation of transporters. Michaelis-Menten constant (Km) of SLC13A5 was estimated to be 24 μM for PF-06649298 in human hepatocytes. In vitro Kpuu obtained from rat suspension hepatocytes supplemented with 4% fatty acid free bovine serum albumin showed good correlation with in vivo Kpuu of liver-to-plasma, illustrating the potential of this approach to predict in vivo Kpuu from in vitro systems.

  2. Design and development of single stage purification of papain using Ionic Liquid based aqueous two phase extraction system and its Partition coefficient studies

    Senthilkumar Rathnasamy


    Full Text Available As an emerging trend in bioseparation, aqueous two phase extractions based on phosponium ionic liquid have been utilized in this work to extract papain from Carica papaya fruit latex and the same wascompared with conventional aqueous two phase extraction system. Factors affecting the partition coefficient of papain such as ionic liquid concentration, pH of the extraction system and temperature have been investigated. The optimization studies show that ionic liquid concentrations and pH are majorly influencing the phaseformations and papain partitioning. It reveals the importance of electrostatic and hydrophobic interactions in the papain partitioning. Purification studies performed on Gel Filtration Chromatography shows that 96% of the papain enzyme could be extracted with the phosponium based ionic liquid in a single stage extraction. The final fraction containing papain enzyme was confirmed by SDS Page analysis.

  3. Solid-solution partitioning of Cd and factors controlling the partitioning coefficient in paddy soil profiles: A case study of the Chengdu Plain in Sichuan Province%重金属元素Cd在水稻土剖面中的分配系数及其影响因素研究:以四川省成都平原区为例

    杨晓燕; 侯青叶; 杨忠芳


    以四川省成都平原区农田生态系统水稻土剖面为例,探讨了Cd分配系数及其影响因素.结果表明:Cd分配系数(Kd)在污染土壤环境和本底土壤环境中是不同的,在剖面PM3、PM-6和PM8剖面中污染环境中分配系数(Kd)大于本底环境中的分配系数.而在剖面PM-7中,本底环境中的分配系数(Kd)大于污染环境中的值.在污染环境Cd分配系数受土壤pH值、交换性Mg和铁硅氧化物的影响比较大,而在非污染环境中分配系数受到土壤可溶性Al、Cd全量和铁锰铝氧化物的影响较大.这些土壤的物化性质对分配系数造成影响,使得土壤滤渣和土壤原土中Cd形态含量存在差异.%For understanding geochemical behaviors of cadmium (Cd). it is essential to study the partitioning coefficient (Kd) of Cd and the factors controlling the Kd in soil environment. This study focuses on the distribution of Cd between the soil solution and soil solid phase in paddy soil profiles in Chengdu agro-ecosystems in Sichuan Province, in order to discuss the factors controlling the partition coefficient. It is known that the KA value of Cd in contaminated soils is different from that in the original soils. In profile PM-3, PM-6 and PM-8. the Kd in the contaminated soil layer is larger than that in the original layers, however, in profile PM-7 it is on the contrary. The results show that the partition coefficient of Cd is closely related with soil physical-chemical properties. The partition coefficient (Kd) is influenced by soil pH. exchangeable Al, and iron and silicon oxides in the contaminated soils, while in the original soils it is extremely sensitive to soil soluble Al, total cadmium and oxides of iron, manganese and aluminum. Because of the impact of these soil physical and chemical properties on the partiliun coefficient, the different distribution of geochemical species of cadmium between the soil residues and the original soils exists.

  4. Determination of Organic Partitioning Coefficients in Water-Supercritical CO 2 Systems by Simultaneous in Situ UV and Near-Infrared Spectroscopies

    Bryce, David A.; Shao, Hongbo; Cantrell, Kirk J.; Thompson, Christopher J.


    CO2 injected into depleted oil or gas reservoirs for long-term storage has the potential to mobilize organic compounds and distribute them between sediments and reservoir brines. Understanding this process is important when considering health and environmental risks, but little quantitative data currently exists on the partitioning of organics between supercritical CO2 and water. In this work, a high-pressure, in situ measurement capability was developed to assess the distribution of organics between CO2 and water at conditions relevant to deep underground storage of CO2. The apparatus consists of a titanium reactor with quartz windows, near-infrared and UV spectroscopic detectors, and switching valves that facilitate quantitative injection of organic reagents into the pressurized reactor. To demonstrate the utility of the system, partitioning coefficients were determined for benzene in water/supercritical CO2 over the range 35-65 °C and approximately 25-150 bar. Density changes in the CO2 phase with increasing pressure were shown to have dramatic impacts on benzene's partitioning behavior. Our partitioning coefficients were approximately 5-15 times lower than values previously determined by ex situ techniques that are prone to sampling losses. The in situ methodology reported here could be applied to quantify the distribution behavior of a wide range of organic compounds that may be present in geologic CO2 storage scenarios.

  5. Partition coefficients for REE between garnets and liquids - Implications of non-Henry's Law behaviour for models of basalt origin and evolution

    Harrison, W. J.


    An experimental investigation of Ce, Sm and Tm rare earth element (REE) partition coefficients between coexisting garnets (both natural and synthetic) and hydrous liquids shows that Henry's Law may not be obeyed over a range of REE concentrations of geological relevance. Systematic differences between the three REE and the two garnet compositions may be explained in terms of the differences between REE ionic radii and those of the dodecahedral site into which they substitute, substantiating the Harrison and Wood (1980) model of altervalent substitution. Model calculations demonstrate that significant variation can occur in the rare earth contents of melts produced from a garnet lherzolite, if Henry's Law partition coefficients do not apply for the garnet phase.

  6. Partition coefficients for REE between garnets and liquids - Implications of non-Henry's Law behaviour for models of basalt origin and evolution

    Harrison, W. J.


    An experimental investigation of Ce, Sm and Tm rare earth element (REE) partition coefficients between coexisting garnets (both natural and synthetic) and hydrous liquids shows that Henry's Law may not be obeyed over a range of REE concentrations of geological relevance. Systematic differences between the three REE and the two garnet compositions may be explained in terms of the differences between REE ionic radii and those of the dodecahedral site into which they substitute, substantiating the Harrison and Wood (1980) model of altervalent substitution. Model calculations demonstrate that significant variation can occur in the rare earth contents of melts produced from a garnet lherzolite, if Henry's Law partition coefficients do not apply for the garnet phase.

  7. Water-soluble gases as partitioning tracers to investigate the pore volume?transmissivity correlation in a fracture

    Lunati, Ivan; Kinzelbach, Wolfgang


    Hydraulically equivalent fractures may show striking differences when a gas-migration experiment is performed because of the different correlations between transmissivity, pore volume and entry pressure. We numerically simulate gas migration between injection and extraction boreholes in a parallel plate fracture with a heterogeneous fault gouge, in a rough-walled fracture filled with homogeneous material, and in a rough-walled empty fracture. The parallel plate model and the empty model clearly show the existence of preferential paths; for high variance of the transmissivity field, gas flow takes place only in few discrete channels separated by water-saturated regions. In contrast, in the fracture filled with homogeneous fault gouge, the gas saturation is continuous and more uniformly distributed. It appears a fundamental issue to be able to discriminate in situ among conceptual models that can yield such a different gas-saturation distribution. As in practice, the saturation distribution cannot be directly observed, tracer experiments are performed to characterize a fracture. For these reasons, we simulate the transport of tracers, which are added to the gas phase as soon as quasi-steady saturation distribution and extraction rate are achieved, and we compare the breakthrough curves obtained assuming different models. Our numerical simulations suggest that discrimination among the models on the basis of single-tracer tests is unlikely. A better tool to investigate fracture properties is provided by a gas-tracer test, in which a cocktail of gases with different water solubility is employed. These gases behave as partitioning tracers and allow us to estimate the gas saturation in the fracture. Indeed, by comparison of the residence-time distributions of different gases, we are able to compute a streamline effective saturation, which is an excellent estimate of fracture saturation. In addition, the streamline effective saturation curve contains information that is

  8. Ion-transfer voltammetry of local anesthetics at an organic solvent/water interface and pharmacological activity vs. ion partition coefficient relationship.

    Kubota, Y; Katano, H; Senda, M


    The ion-transfer reaction of local anesthetics at an organic solvent/water interface has been studied using cyclic voltammetry (CV) with a stationary nitrobenzene (NB)/water (W) interface. Procaine and seven other local anesthetics gave reversible or quasi-reversible voltammograms at the NB/W interface in the pH range between 0.9 and 9.6. These drugs are present in aqueous solution in either neutral or ionic form, or both forms. The half-wave potential, as determined by the midpoint potential in CV, vs. pH curves, were determined and analyzed to determine the partition coefficients of both neutral and ionic forms of the drugs between NB and W. The partition coefficients of the ionic forms were derived from their formal potential of transfer at an NB/W interface. The dissociation constants of ionic forms of the drugs in NB were also deduced. A high correlation between the pharmacological activity and the partition coefficient of the ionic form of amide-linked local anesthetics has been shown.

  9. Chemical Potentials, Activity Coefficients, and Solubility in Aqueous NaCl Solutions: Prediction by Polarizable Force Fields.

    Moučka, Filip; Nezbeda, Ivo; Smith, William R


    We describe a computationally efficient molecular simulation methodology for calculating the concentration dependence of the chemical potentials of both solute and solvent in aqueous electrolyte solutions, based on simulations of the salt chemical potential alone. We use our approach to study the predictions for aqueous NaCl solutions at ambient conditions of these properties by the recently developed polarizable force fields (FFs) AH/BK3 of Kiss and Baranyai (J. Chem. Phys. 2013, 138, 204507) and AH/SWM4-DP of Lamoureux and Roux (J. Phys. Chem. B 2006, 110, 3308 - 3322) and by the nonpolarizable JC FF of Joung and Cheatham tailored to SPC/E water (J. Phys. Chem. B 2008, 112, 9020 - 9041). We also consider their predictions of the concentration dependence of the electrolyte activity coefficient, the crystalline solid chemical potential, the electrolyte solubility, and the solution specific volume. We first highlight the disagreement in the literature concerning calculations of solubility by means of molecular simulation in the case of the JC FF and provide strong evidence of the correctness of our methodology based on recent independently obtained results for this important test case. We then compare the predictions of the three FFs with each other and with experiment and draw conclusions concerning their relative merits, with particular emphasis on the salt chemical potential and activity coefficient vs concentration curves and their derivatives. The latter curves have only previously been available from Kirkwood-Buff integrals, which require approximate numerical integrations over system pair correlation functions at each concentration. Unlike the case of the other FFs, the AH/BK3 curves are nearly parallel to the corresponding experimental curves at moderate and higher concentrations. This leads to an excellent prediction of the water chemical potential via the Gibbs-Duhem equation and enables the activity coefficient curve to be brought into excellent agreement

  10. Distributions of the particle/gas and dust/gas partition coefficients for seventy-two semi-volatile organic compounds in indoor environment.

    Wei, Wenjuan; Mandin, Corinne; Blanchard, Olivier; Mercier, Fabien; Pelletier, Maud; Le Bot, Barbara; Glorennec, Philippe; Ramalho, Olivier


    Particle/gas and dust/gas partition coefficients (Kp and Kd) are two key parameters that address the partitioning of semi-volatile organic compounds (SVOCs) between gas-phase, airborne particles, and settled dust in indoor environment. A number of empirical equations to calculate the values of Kp and Kd have been reported in the literature. Therefore, the difficulty lies in the selection of a specific empirical equation in a given situation. In this study, we retrieved from the literature 38 empirical equations for calculating Kp and Kd values from the SVOC saturation vapor pressure and octanol/air partition coefficient. These values were calculated for 72 SVOCs: 9 phthalates, 9 polybrominated diphenyl ethers (PBDEs), 11 polychlorinated biphenyls (PCBs), 22 biocides, 14 polycyclic aromatic hydrocarbons (PAHs), 3 alkylphenols, 2 synthetic musks, tributylphosphate, and bisphenol A. The mean and median values of log10Kp or log10Kd for most SVOCs were of the same order of magnitude. The distribution of log10Kp values was fitted to either a normal distribution (for 27 SVOCs) or a log-normal distribution (for 45 SVOCs). This work provides a reference distribution of the log10Kp for 72 SVOCs, and its use may reduce the bias associated with the selection of a specific value or equation.

  11. Liquid/air partition coefficients of methyl and ethyl T-butyl ethers, T-amyl methyl ether, and T-butyl alcohol.

    Nihlen, A; Lof, A; Johanson, G


    Partition coefficients are essential to a description of the uptake and distribution of volatile substances in humans and in the development of physiologically based pharmacokinetic models. Liquid/air partition coefficients (lambda) of three ethers, methyl t-butyl ether (MTBE), ethyl t-butyl ether (ETBE), and t-amyl methyl ether (TAME) were determined in vitro by head space-gas chromatography. These ethers, and especially MTBE, are used in unleaded gasoline to enhance the oxygen and octane content, and to reduce the output of carbon monoxide during combustion. Partition coefficients of t-butyl alcohol (TBA), a metabolite of MTBE, were determined also. The liquids tested were fresh human blood, water (physiological saline), and olive oil. The (lambda)blood/air values were: 17.7 (95% confidence interval 17.0-18.4) for MTBE; 11.7 (11.3-12.1) for ETBE; and 17.9 (17.3-18.5) for TAME. Corresponding (lambda)water/air values were 15.2 (14.9-15.5), 8.39 (8.19-8.59), and 11.9 (11.7-12.1). The ethers have a higher affinity for oil, the values for (lambda)oil/air being 120 (114-125), 190 (183-197), and 337 (320-354), respectively. As expected, the (lambda)blood/air and (lambda)water/air for TBA were much higher than for the ethers, 462 (440-484) and 603 (590-617), respectively. The (lambda)oil/air was 168 (161-174) for TBA. The interindividual variability of the (lambda)blood/air (10 subjects) was calculated as the coefficient of variation, and estimated as: 14% for MTBE, 20% for ETBE, 20% for TAME, and 30% for TBA. No significant difference was seen in the (lambda)blood/air between the sexes.

  12. Derivation of the ion temperature partition coefficient {beta}{sub {parallel}} from the study of ion frictional heating events

    McCrea, I.W. [Rutherford Appleton Lab., Oxfordshire (United Kingdom); Lester, M.; Robinson, T.R.; Wade, N.M.; Jones, T.B. [Univ. of Leicester (United Kingdom); St. Maurice, J.P. [Univ. of Western Ontario, London (Canada)


    Analyzing data from the EISCAT CP-0 experiment the authors report on values of the ion temperature partition function {beta}{sub {parallel}}. The measurements are made parallel to the geomagnetic field, and therefore the line-of-sight thermal velocity is well approximated by a maxwellian distribution. This gives a fairly straight forward way to study ion energy balance in the F region.

  13. Towards the rational design of novel drugs based on solubility, partitioning/distribution, biomimetic permeability and biological activity exemplified by 1,2,4-thiadiazole derivatives

    Volkova, T. V.; Terekhova, I. V.; Silyukov, O. I.


    Novel 1,2,4-thiadiazole derivatives as potent neuroprotectors were synthesized and identified. Their ability to inhibit the glutamate stimulated Ca2+ uptake was investigated. The solubility of thiadiazoles was measured in a buffer solution (pH 7.4) at 298 K. The distribution coefficients in 1-oct...

  14. Experimental and CFD-PBM Study of Oxygen Mass Transfer Coefficient in Different Impeller Configurations and Operational Conditions of a Two-Phase Partitioning Bioreactor.

    Moradkhani, Hamed; Izadkhah, Mir-Shahabeddin; Anarjan, Navideh


    In this work, gas dispersion in a two-phase partitioning bioreactor is analyzed by calculating volumetric oxygen mass transfer coefficient which is modeled using a commercial computational fluid dynamics (CFD), code FLUENT 6.2. Dispersed oxygen bubbles dynamics is based on standard "k-ε" Reynolds-averaged Navier-Stokes (RANS) model. This paper describes a three-dimensional CFD model coupled with population balance equations (PBE) in order to get more confirming results of experimental measurements. Values of k L a are obtained using dynamic gassing-out method. Using the CFD simulation, the volumetric mass transfer coefficient is calculated based on Higbie's penetration theory. Characteristics of mass transfer coefficient are investigated for five configurations of impeller and three different aeration flow rates. The pitched six blade type, due to the creation of downward flow direction, leads to higher dissolved oxygen (DO) concentrations, thereby, higher values of k L a compared with other impeller compositions. The magnitude of dissolved oxygen percentage in the aqueous phase has direct correlation with impeller speed and any increase of the aeration magnitude leads to faster saturation in shorter periods of time. Agitation speeds of 300 to 800 rpm are found to be the most effective rotational speeds for the mass transfer of oxygen in two-phase partitioning bioreactors (TPPB).

  15. Water-solvent partition coefficients and Delta Log P values as predictors for blood-brain distribution; application of the Akaike information criterion.

    Abraham, Michael H; Acree, William E; Leo, Albert J; Hoekman, David; Cavanaugh, Joseph E


    It is shown that log P values for water-alkane or water-cyclohexane partitions, and the corresponding Delta log P values when used as descriptors for blood-brain distribution, as log BB, yield equations with very poor correlation coefficients but very good standard deviations, S from 0.25 to 0.33 log units. Using quite large data sets, we have verified that similar S-values apply to predictions of log BB. A suggested model, based on log P for water-dodecane and water-hexadecane partition coefficients, has 109 data points and a fitted S = 0.254 log units. It is essential to include in the model an indicator variable for volatile compounds, and an indicator variable for drugs that contain the carboxylic group. A similar equation based on water-chloroform partition coefficients has 83 data points and a fitted S = 0.287 log units. We can find no causal connection between these log P values and log BB in terms of correlation or in terms of chemical similarity, but conclude that the log P descriptor will yield excellent predictions of log BB provided that predictions are within the chemical space of the compounds used to set up the model. We also show that model based on log P(octanol) and an Abraham descriptor provides a simple and easy method of predicting log BB with an error of no more than 0.31 log units. We have used the Akaike information criterion to investigate the most economic models for log BB.

  16. The liver partition coefficient-corrected inhibitory quotient and the pharmacokinetic-pharmacodynamic relationship of directly acting anti-hepatitis C virus agents in humans.

    Duan, Jianmin; Bolger, Gordon; Garneau, Michel; Amad, Ma'an; Batonga, Joëlle; Montpetit, Hélène; Otis, François; Jutras, Martin; Lapeyre, Nicole; Rhéaume, Manon; Kukolj, George; White, Peter W; Bethell, Richard C; Cordingley, Michael G


    Pharmacokinetic-pharmacodynamic (PK-PD) data analyses from early hepatitis C virus (HCV) clinical trials failed to show a good correlation between the plasma inhibitory quotient (IQ) and antiviral activity of different classes of directly acting antiviral agents (DAAs). The present study explored whether use of the liver partition coefficient-corrected IQ (LCIQ) could improve the PK-PD relationship. Animal liver partition coefficients (Kp(liver)) were calculated from liver to plasma exposure ratios. In vitro hepatocyte partition coefficients (Kp(hep)) were determined by the ratio of cellular to medium drug concentrations. Human Kp(liver) was predicted using an in vitro-in vivo proportionality method: the species-averaged animal Kp(liver) multiplied by the ratio of human Kp(hep) over those in animals. LCIQ was calculated using the IQ multiplied by the predicted human Kp(liver). Our results demonstrated that the in vitro-in vivo proportionality approach provided the best human Kp(liver) prediction, with prediction errors of <45% for all 5 benchmark drugs evaluated (doxorubicin, verapamil, digoxin, quinidine, and imipramine). Plasma IQ values correlated poorly (r(2) of 0.48) with maximum viral load reduction and led to a corresponding 50% effective dose (ED(50)) IQ of 42, with a 95% confidence interval (CI) of 0.1 to 148534. In contrast, the LCIQ-maximum VLR relationship fit into a typical sigmoidal curve with an r(2) value of 0.95 and an ED(50) LCIQ of 121, with a 95% CI of 83 to 177. The present study provides a novel human Kp(liver) prediction model, and the LCIQ correlated well with the viral load reductions observed in short-term HCV monotherapy of different DAAs and provides a valuable tool to guide HCV drug discovery.

  17. Characterizing PUF disk passive air samplers for alkyl-substituted PAHs: Measured and modelled PUF-AIR partition coefficients with COSMO-RS.

    Parnis, J Mark; Eng, Anita; Mackay, Donald; Harner, Tom


    Isomers of alkyl-substituted polycyclic aromatic hydrocarbons (PAHs) and dibenzothiophenes are modelled with COSMO-RS theory to determine the effectiveness and accuracy of this approach for estimation of isomer-specific partition coefficients between air and polyurethane foam (PUF), i.e., KPUF-AIR. Isomer-specific equilibrium partitioning coefficients for a series of 23 unsubstituted and isomeric alkyl-substituted PAHs and dibenzothiophenes were measured at 22 °C. This data was used to determine the accuracy of estimated values using COSMO-RS, which is isomer specific, and the Global Atmospheric Passive Sampling (GAPS) template approach, which treats all alkyl-substitutions as a single species of a given side-chain carbon number. A recently developed oligomer-based model for PUF was employed, which consisted of a 1:1 condensed pair of 2,4-toluene-diisocyanide and glycerol. The COSMO-RS approach resulted in a significant reduction in the RMS error associated with simple PAHs and dibenzothiophene compared with the GAPS template approach. When used with alkylated PAHs and dibenzothiophenes grouped into carbon-number categories, the GAPS template approach gave lower RMS error (0.72) compared to the COSMO-RS result (0.87) when the latter estimates were averaged within the carbon-number-based categories. When the isomer-specific experimental results were used, the COSMO-RS approach resulted in a 21% reduction in RMS error with respect to the GAPS template approach, with a 0.57 RMS error for all alkylated PAHs and dibenzothiophenes studied. The results demonstrate that COSMO-RS theory is effective in generating isomer-specific PUF-air partition coefficients, supporting the application of PUF-based passive samplers for monitoring and research studies of polycyclic aromatic compounds (PACs) in air.

  18. Calculation Method for Horizontal Partition Coefficient of Simply Supported T -shaped beam%简支T梁横向分配系数计算方法



    On account of simply supported T - shaped beam bridge, the horizontal partition coefficient is cal- culated with G- M method, rigid cross beam method and rigid connected beam method and suitable methods are summarized, with certain reference value for design.%针对简支T型梁桥,采用G-M法、刚性横梁法、刚接梁法计算横向分配系数,总结了合适的计算方法,对设计工作具有一定的参考价值。

  19. Real time investigation of the effect of thermal expansion coefficient mismatch on film-substrate strain partitioning in Ag/Si systems

    Das, Debolina; Banu, Nasrin; Bisi, Bhaskar; Mahato, J. C.; Srihari, V.; Halder, Rumu; Dev, B. N.


    We have used X-ray diffraction (XRD) to investigate strain partitioning between an epitaxial layer and the substrate as a function of temperature, where the substrate (Si) and the epilayer material (Ag) have large thermal expansion coefficient (α) mismatch. The Ag/Si(111) system undergoes morphological changes upon heating, and the larger and taller islands are formed exposing more substrate surfaces. Sample heating was carried out under nitrogen flow. At >300 °C, the Si(111) diffraction peak splits into three. One of these components conforms to the thermal expansion of bulk Si. The other two components correspond to a highly nonlinear decrease and increase of Si-d(111) planar spacing. The decreasing component has been associated with strained Si under Ag and the increasing component with strained Si under SiO2, which has been formed partly prior to the XRD experiment and partly during sample heating. The opposite trends of these two Si-d(111) components are because of the larger value of α for Ag (7 times) and smaller for SiO2 (1/5th) compared to Si. The out-of-plane strain partitioning has been such that at room temperature, the Si substrate is unstrained and the strain in Ag is ˜0.3%. At 800 °C, Ag is practically relaxed, while Si under Ag is ˜-0.7% strained. A temperature dependent strain partitioning factor has been introduced to fit the data.

  20. Enhancement of the 1-Octanol/Water Partition Coefficient of the Anti-Inflammatory Indomethacin in the Presence of Lidocaine and Other Local Anesthetics.

    Tateuchi, Ryo; Sagawa, Naoki; Shimada, Yohsuke; Goto, Satoru


    Side effects and excessive potentiation of drug efficacy caused by polypharmacy are becoming important social issues. The apparent partition coefficient of indomethacin (log P'IND) increases in the presence of lidocaine, and this is used as a physicochemical model for investigating polypharmacy. We examined the changes in log P'IND caused by clinically used local anesthetics-lidocaine, tetracaine, mepivacaine, bupivacaine, and dibucaine-and by structurally similar basic drugs-procainamide, imipramine, and diltiazem. The quantitative structure-activity relationship study of log P'IND showed that the partition coefficient values (log PLA) and the structural entropic terms (ΔSobs, log f) of the additives affect log P'IND. These results indicate that the local anesthetics and structurally similar drugs function as phase-transfer catalysts, increasing the membrane permeability of indomethacin via heterogeneous intermolecular association. Therefore, we expect that the potency of indomethacin, an acidic nonsteroidal anti-inflammatory drug, will be increased by concurrent administration of the other drugs.

  1. Experimental Determination of Spinel/Melt, Olivine/Melt, and Pyroxene/Melt Partition Coefficients for Re, Ru, Pd, Au, and Pt

    Righter, K.; Campbell, A. J.; Humayun, M.


    Experimental studies have identified spinels as important hosts phases for many of the highly siderophile elements (HSE). Yet experimental studies involving chromite or Cr-rich spinel have been lacking. Experimental studies of partitioning of HSEs between silicate, oxides and silicate melt are plagued by low solubilities and the presence of small metallic nuggets at oxygen fugacities relevant to magmas, which interfere with analysis of the phases of interest. We have circumvented these problems in two ways: 1) performing experiments at oxidized conditions, which are still relevant to natural systems but in which nuggets are not observed, and 2) analysis of run products with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), allowing a combination of high sensitivity and good spatial resolution.

  2. The effect of dietary water soluble carbohydrate to nitrogen ratio on nitrogen partitioning and isotopic fractionation of lactating goats offered a high-nitrogen diet.

    Cheng, L; Edwards, G R; Dewhurst, R J; Nicol, A M; Pacheco, D


    The objective of this study was to investigate the relationship between nitrogen (N) partitioning and isotopic fractionation in lactating goats consuming diets with a constant high concentration of N and increasing levels of water soluble carbohydrate (WSC). Eight lactating goats were offered four different ratios of WSC : N in the diet. A two-period incomplete cross-over design was used, with two goats assigned to each treatment in each period. N balance measurements were conducted, with measurement of feed N intake and total output of N in milk, faeces and urine. Treatment, period and infusion effects were tested using general ANOVA; the relationships between variables were analysed by linear regression. Dietary treatment and period had significant effects on dry matter (DM) intake (g/day). DM digestibility (g/kg DM) and N digestibility (g/kg N) increased as the ratio of WSC : N increased in the diet. No treatment effect was observed on milk urea N concentration (g/l) or urinary excretion of purine derivatives (mM/day). Although dietary treatment and period had significant effects on N intake, the change of N intake was small; no effect was observed for N partitioning among faeces, milk and urine. Milk, plasma and faeces were enriched in 15N compared with feed, whilst urine was depleted in 15N relative to feed. No significant relationship was established between N partitioning and isotopic fractionation. This study failed to confirm the potential to use N isotopic fractionation as an indicator of N partitioning in dairy goats when diets provided N in excess to requirements, most likely because the range of milk N output/N intake and urinary N output/N intake were narrow.

  3. Zirconium, hafnium, and rare earth element partition coefficients for ilmenite and other minerals in high-Ti lunar mare basalts - An experimental study

    Mckay, G.; Wagstaff, J.; Yang, S.-R.


    Partition coefficients were determined for Gd, Lu, Hf and Zr among ilmenite, armalcolite, and synthetic high-Ti mare basaltic melts at temperatures from 1122 deg to 1150 deg, and at oxygen fugacities of IW x 10 exp 0.5, by in situ analysis with an electron microprobe, using samples doped to present concentration levels. Coefficients for Zr were also measured for samples containing 600-1600 ppm Zr using this microprobe. In addition, coefficients were determined for Hf and Zr between chromian ulvospinel and melt, for Hf between pigeonite and melt, and for Lu between olivine and melt by microprobe analysis of samples doped to present levels. Values measured using the microprobe were in agreement with the values measured by analyzing mineral separates from the same run products by isotope dilution. Coefficient values for ilmenite are less than 0.01 for the LREE, are around 0.1 for the HREE, and are several times greater than this for Zr and Hf.

  4. Zirconium, hafnium, and rare earth element partition coefficients for ilmenite and other minerals in high-Ti lunar mare basalts - An experimental study

    Mckay, G.; Wagstaff, J.; Yang, S.-R.


    Partition coefficients were determined for Gd, Lu, Hf and Zr among ilmenite, armalcolite, and synthetic high-Ti mare basaltic melts at temperatures from 1122 deg to 1150 deg, and at oxygen fugacities of IW x 10 exp 0.5, by in situ analysis with an electron microprobe, using samples doped to present concentration levels. Coefficients for Zr were also measured for samples containing 600-1600 ppm Zr using this microprobe. In addition, coefficients were determined for Hf and Zr between chromian ulvospinel and melt, for Hf between pigeonite and melt, and for Lu between olivine and melt by microprobe analysis of samples doped to present levels. Values measured using the microprobe were in agreement with the values measured by analyzing mineral separates from the same run products by isotope dilution. Coefficient values for ilmenite are less than 0.01 for the LREE, are around 0.1 for the HREE, and are several times greater than this for Zr and Hf.

  5. Determination of Sr and Ba partition coefficients between apatite from fish ( Sparus aurata) and seawater: The influence of temperature

    Balter, Vincent; Lécuyer, Christophe


    The Sr/Ca and Ba/Ca ratios in inorganic apatite are strongly dependent on the temperature of the aqueous medium during precipitation. If valid in biogenic apatite, these thermometers would offer the advantage of being more resistant to diagenesis than those calibrated on biogenic calcite and aragonite. We have reared seabreams ( Sparus aurata) in tanks with controlled conditions during experiments lasting for more than 2 years at 13, 17, 23 and 27 °C, in order to determine the variations in Sr and Ba partitioning relative to Ca ( DSr and DBa, respectively) between seawater and fish apatitic hard tissues (i.e. teeth and bones), as a function of temperature. The sensitivity of the Sr and Ba thermometers (i.e. ∂ DSr/∂ T and ∂ DBa/∂ T, respectively), are similar in bone ( ∂Db-wSr/∂ T = 0.0036 ± 0.0003 and ∂Db-wBa/∂ T = 0.0134 ± 0.0026, respectively) and enamel ( ∂De-wSr/∂ T = 0.0037 ± 0.0005 and ∂De-wBa/∂ T = 0.0107 ± 0.0026, respectively). The positive values of ∂ DSr/∂ T and ∂ DBa/∂ T in bone and enamel indicate that DSr and DBa increase with increasing temperature, a pattern opposite to that observed for inorganic apatite. This distinct thermodependent trace element partitioning between inorganic and organic apatite and water highlights the contradictory effects of the crystal-chemical and biological controls on the partitioning of Ca, Sr and Ba in vertebrate organisms. Taking into account the diet Sr/Ca and Ba/Ca values, it is shown that the bone Ba/Ca signature of fish can be explained by Ca-biopurification and inorganic apatite precipitation, whereas both of these processes fail to predict the bone Sr/Ca values. Therefore, the metabolism of Ca as a function of temperature still needs to be fully understood. However, the biogenic Sr thermometer is used to calculate an average seawater temperature of 30.6 °C using the Sr/Ca compositions of fossil shark teeth at the Cretaceous/Tertiary boundary, and a typical seawater Sr

  6. Estimation of gas-particle partitioning coefficients (Kp) of carcinogenic polycyclic aromatic hydrocarbons in carbonaceous aerosols collected at Chiang-Mai, Bangkok and Hat-Yai, Thailand.

    Pongpiachan, Siwatt; Ho, Kin Fai; Cao, Junji


    To assess environmental contamination with carcinogens, carbonaceous compounds, water-soluble ionic species and trace gaseous species were identified and quantified every three hours for three days at three different atmospheric layers at the heart of Chiang-Mai, Bangkok and Hat-Yai from December 2006 to February 2007. A DRI Model 2001 Thermal/Optical Carbon Analyzer with the IMPROVE thermal/optical reflectance (TOR) protocol was used to quantify the organic carbon (OC) and elemental carbon (EC) contents in PM10. Diurnal and vertical variability was also carefully investigated. In general, OC and EC mass concentration showed the highest values at the monitoring period of 21.00-00.00 as consequences of human activities at night bazaar coupled with reduction of mixing layer, decreased wind speed and termination of photolysis at nighttime. Morning peaks of carbonaceous compounds were observed during the sampling period of 06:00-09:00, emphasizing the main contribution of traffic emission in the three cities. The estimation of incremental lifetime particulate matter exposure (ILPE) raises concern of high risk of carbonaceous accumulation over workers and residents living close to the observatory sites. The average values of incremental lifetime particulate matter exposure (ILPE) of total carbon at Baiyoke Suit Hotel and Baiyoke Sky Hotel are approximately ten times higher than those air samples collected at Prince of Songkla University Hat-Yai campus corpse incinerator and fish-can manufacturing factory but only slightly higher than those of rice straw burning in Songkla province. This indicates a high risk of developing lung cancer and other respiratory diseases across workers and residents living in high buildings located in Pratunam area. Using knowledge of carbonaceous fractions in PM10, one can estimate the gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs). Dachs-Eisenreich model highlights the crucial role of adsorption in gas

  7. Experimental determination of the partitioning coefficient and volatility of important BVOC oxidation products using the Aerosol Collection Module (ACM) coupled to a PTR-ToF-MS

    Gkatzelis, G.; Hohaus, T.; Tillmann, R.; Schmitt, S. H.; Yu, Z.; Schlag, P.; Wegener, R.; Kaminski, M.; Kiendler-Scharr, A.


    Atmospheric aerosol can alter the Earth's radiative budget and global climate but can also affect human health. A dominant contributor to the submicrometer particulate matter (PM) is organic aerosol (OA). OA can be either directly emitted through e.g. combustion processes (primary OA) or formed through the oxidation of organic gases (secondary organic aerosol, SOA). A detailed understanding of SOA formation is of importance as it constitutes a major contribution to the total OA. The partitioning between the gas and particle phase as well as the volatility of individual components of SOA is yet poorly understood adding uncertainties and thus complicating climate modelling. In this work, a new experimental methodology was used for compound-specific analysis of organic aerosol. The Aerosol Collection Module (ACM) is a newly developed instrument that deploys an aerodynamic lens to separate the gas and particle phase of an aerosol. The particle phase is directed to a cooled sampling surface. After collection particles are thermally desorbed and transferred to a detector for further analysis. In the present work, the ACM was coupled to a Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS) to detect and quantify organic compounds partitioning between the gas and particle phase. This experimental approach was used in a set of experiments at the atmosphere simulation chamber SAPHIR to investigate SOA formation. Ozone oxidation with subsequent photochemical aging of β-pinene, limonene and real plant emissions from Pinus sylvestris (Scots pine) were studied. Simultaneous measurement of the gas and particle phase using the ACM-PTR-ToF-MS allows to report partitioning coefficients of important BVOC oxidation products. Additionally, volatility trends and changes of the SOA with photochemical aging are investigated and compared for all systems studied.

  8. Variable volume loading method: a convenient and rapid method for measuring the initial emittable concentration and partition coefficient of formaldehyde and other aldehydes in building materials.

    Xiong, Jianyin; Yan, Wei; Zhang, Yinping


    The initial emittable formaldehyde and VOC concentration in building materials (C(0)) is a key parameter for characterizing and classifying these materials. Various methods have been developed to measure this parameter, but these generally require a long test time. In this paper we develop a convenient and rapid method, the variable volume loading (VVL) method, to simultaneously measure C(0) and the material/air partition coefficient (K). This method has the following features: (a) it requires a relatively short experimental time (less than 24 h for the cases studied); and (b) is convenient for routine measurement. Using this method, we determined C(0) and K of formaldehyde, propanal and hexanal in one kind of medium density fiberboard, and repeated experiments were performed to reduce measurement error. In addition, an extended-C-history method is proposed to determine the diffusion coefficient and the convective mass transfer coefficient. The VVL method is validated by comparing model predicted results based on the determined parameters with experimental data. The determined C(0) of formaldehyde obtained via this method is less than 10% of the total concentration using the perforator method recommended by the Chinese National Standard, suggesting that the total concentration may not be appropriate to predict emission characteristics, nor for material classification.

  9. Prediction of partition coefficient of some 3-hydroxy pyridine-4-one derivatives using combined partial least square regression and genetic algorithm.

    Shahlaei, M; Fassihi, A; Saghaie, L; Zare, A


    A quantiatative structure property relationship (QSPR) treatment was used to a data set consisting of diverse 3-hydroxypyridine-4-one derivatives to relate the logarithmic function of octanol:water partition coefficients (denoted by log po/w) with theoretical molecular descriptors. Evaluation of a test set of 6 compounds with the developed partial least squares (PLS) model revealed that this model is reliable with a good predictability. Since the QSPR study was performed on the basis of theoretical descriptors calculated completely from the molecular structures, the proposed model could potentially provide useful information about the activity of the studied compounds. Various tests and criteria such as leave-one-out cross validation, leave-many-out cross validation, and also criteria suggested by Tropsha were employed to examine the predictability and robustness of the developed model.

  10. New insight into pesticide partition coefficient Kd for modelling pesticide fluvial transport: application to an agricultural catchment in south-western France.

    Boithias, Laurie; Sauvage, Sabine; Merlina, Georges; Jean, Séverine; Probst, Jean-Luc; Sánchez Pérez, José Miguel


    Pesticides applied on crops are leached with rainfall to groundwater and surface water. They threat the aquatic environment and may render water unfit for human consumption. Pesticide partitioning is one of the pesticide fate processes in the environment that should be properly formalised in pesticide fate models. Based on the analysis of 7 pesticide molecules (alachlor, atrazine, atrazine's transformation product deethylatrazine or DEA, isoproturon, tebuconazole and trifluralin) sampled from July 2009 to October 2010 at the outlet of the river Save (south-western France), the objectives of this study were (1) to check which of the environmental factors (discharge, pH, concentrations of total suspended matter (TSM), dissolved organic carbon (DOC) and particulate organic carbon (POC) could control the pesticide sorption dynamic, and (2) to establish a relationship between environmental factors, the partition coefficient Kd and the octanol/water distribution coefficient Kow. The comparison of physico-chemical parameters values during low flow and high flow shows that discharge, TSM and POC are the factors most likely controlling the pesticide sorption processes in the Save river network, especially for lower values of TSM (below 13mgL(-1)). We therefore express Kd depending on the widely literature-related variable Kow and on the commonly simulated variable TSM concentration. The equation can be implemented in any model describing the fluvial transport and fate of pesticides in both dissolved and sorbed phases, thus, Kd becomes a variable in time and space. The Kd calculation method can be applied to a wide range of catchments and organic contaminants.

  11. Mg-perovskite/silicate melt partition coefficients in the CMS system at 2430 C and 226 Kbars

    Mcfarlane, Elisabeth A.; Drake, Michael J.; Gasparik, Tibor


    The partitioning of elements among lower mantle phases and silicate melts is of interest in unraveling the early thermal history of the Earth. Because of the technical difficulty in carrying out such measurements, only one direct set of measurements has been reported, and these results as well as interpretations based on them have generated controversy. The first set of direct measurements on a synthetic system in the CaO-MgO-SiO2 (CMS) is reported. An experiment was conducted at Stony Brook, using the USSA-2000 split sphere anvil apparatus. An experiment in the CMS system doped with oxides of Al, Ti, Sc, and Sm and run at a nominal temperature of 2380 C and pressure of 226 kbars is reported. Nominal temperatures were measured with a W 3 percent Re/W 25 percent Re thermocouple. The hot spot temperature, where the liquidus is located, is estimated to be at 2430 C. A 10 mm MgO octahedron was used in concert with 4 mm truncation edge lengths on the WC cubes. The sample was contained in a Re capsule which was inserted into a LaCrO3 furnace. Pressure was calibrated at 2000 C. Run duration was approximately 3 minutes. The charge was mounted in epoxy and analyzed using a CAMECA SX-50 electron microprobe. Standard operating conditions were employed, although counting time for the less abundant elements was increased to improved counting statistics. The melt is unquenchable, and forms a dendritic intergrowth of quench crystals and residual melt. It was analyzed using a 30 micron raster. The structural identity of the Mg-perovskite phase was confirmed using x ray microdiffractometry. The results of the investigation are presented.

  12. Zr and Nb partition coefficients - Implications for the genesis of mare basalts, KREEP, and sea floor basalts

    Mccallum, I. S.; Charette, M. P.


    The distribution coefficients of Zr and Nb have been found between armalcolite, ilmenite, clinopyroxene, rutile, plagioclase, and a coexisting high-Ti mare basalt melt in the 1105-1128 C temperature range. Henry's Law is not broken over the compositional range evaluated. The distribution coefficients of clinopyroxene are strongly dependent on melt and crystal compositions. The Al2O3 activity in the melt is a strong controlling parameter. It is concluded that: (1) Apollo 11 (low K) and Apollo 17 high-Ti mare basalts may have been generated by the partial melting of an ilmenite-rich cumulate, (2) Apollo 11 (high K) basalts may have been generated by a small amount of partial melting of a more fractionated ilmenite-rich cumulate, (3) KREEP magmas may have been formed as residual melts produced by fractional crystallization of the lunar magma ocean, and (4) anomalous (type II) MOR basalts may have been generated by small degrees of partial melting of a relatively undepleted mantle with clinopyroxene remaining in the residium.

  13. Determination of the subcutaneous tissue to blood partition coefficient in patients with severe leg ischaemia by a double isotope washout technique

    Bjerre-Jepsen, K; Faris, I; Henriksen, O;


    Knowledge of the tissue to blood partition coefficient (lambda) is essential for calculation of the perfusion coefficient in a single tissue based on measurements of the washout of locally injected isotopes. No measurements of lambda for Xenon in subcutaneous tissue in the leg have been done...... subcutaneously laterally on the calf and in the first interosseous space on the foot. The time until the curves followed a monoexponential course varied between 15 and 45 min in the calf and 5 and 45 min in the foot. The calculated lambda for Xe showed a great variance between individuals in calf as well as foot....... Mean value was 3.7 ml X g-1 (range: 1 X 7-10 X 7) in the calf and 2 X 7 ml X g-1 (range: 1 X 2-4 X 9) in the foot. It is concluded that lambda measurements are necessary for determination of subcutaneous blood flow from 133Xe washout curves in these patients. Determination of lambda is especially...

  14. QSAR Model of Unbound Brain-to-Plasma Partition Coefficient, Kp,uu,brain: Incorporating P-glycoprotein Efflux as a Variable.

    Dolgikh, Elena; Watson, Ian A; Desai, Prashant V; Sawada, Geri A; Morton, Stuart; Jones, Timothy M; Raub, Thomas J


    We report development and prospective validation of a QSAR model of the unbound brain-to-plasma partition coefficient, Kp,uu,brain, based on the in-house data set of ∼1000 compounds. We discuss effects of experimental variability, explore the applicability of both regression and classification approaches, and evaluate a novel, model-within-a-model approach of including P-glycoprotein efflux prediction as an additional variable. When tested on an independent test set of 91 internal compounds, incorporation of P-glycoprotein efflux information significantly improves the model performance resulting in an R(2) of 0.53, RMSE of 0.57, Spearman's Rho correlation coefficient of 0.73, and qualitative prediction accuracy of 0.8 (kappa = 0.6). In addition to improving the performance, one of the key advantages of this approach is the larger chemical space coverage provided indirectly through incorporation of the in vitro, higher throughput data set that is 4 times larger than the in vivo data set.

  15. Effects of pH, sample size, and solvent partitioning on recovery of soluble phenolic acids and isoflavonoids in leaves and stems of red clover (Trifolium pratense cv. Kenland).

    Kagan, Isabelle A


    Several extraction parameters were tested to determine optimal conditions for extracting phenolics from leaves and stems of red clover (Trifolium pratense L. cv. Kenland), with the goal of using extracts in bioassays and in assessment of phenolic profiles. HPLC-UV profiles were compared before and after partitioning a methanolic extract of soluble phenolics with ethyl acetate-ethyl ether (1:1, v/v). The effect of extract pH on the partitioning of phenolics into the ethyl acetate-ethyl ether (EtOAc-Et2O) phase was evaluated, and several tissue weights were extracted to determine a minimum amount that could be extracted without loss of information. HPLC profiles of soluble phenolics were similar in the methanolic extracts and the partitioned EtOAc-Et2O extracts. However, recoveries in unpartitioned extracts were 2- to 4-fold greater than in the acidified, partitioned extracts. Also, recovery was considerably affected by the pH to which extracts were adjusted prior to partitioning. In extracts acidified to pH 2, recoveries were 2- to 7-fold higher than in extracts partitioned at pH 6. In extracts prepared from 250, 120, or 60 mg of tissue, peak areas of methanolic extracts were directly proportional to the amount of tissue extracted.

  16. Study of the partition coefficients Kp/f of seven model migrants from LDPE polymer in contact with food simulants.

    Paseiro-Cerrato, Rafael; Tongchat, Chinawat; Franz, Roland


    This study evaluated the influence of parameters such as temperature and type of low-density polyethylene (LDPE) film on the log Kp/f values of seven model migrants in food simulants. Two different types of LDPE films contaminated by extrusion and immersion were placed in contact with three food simulants including 20% ethanol, 50% ethanol and olive oil under several time-temperature conditions. Results suggest that most log Kp/f values are little affected by these parameters in this study. In addition, the relation between log Kp/f and log Po/w was established for each food simulant and regression lines, as well as correlation coefficients, were calculated. Correlations were compared with data from real foodstuffs. Data presented in this study could be valuable in assigning certain foods to particular food simulants as well as predicting the mass transfer of potential migrants into different types of food or food simulants, avoiding tedious and expensive laboratory analysis. The results could be especially useful for regulatory agencies as well as for the food industry.

  17. Linear solvation energy relationship of the limiting partition coefficient of organic solutes between water and activated carbon

    Luehrs, Dean C.; Hickey, James P.; Nilsen, Peter E.; Godbole, K.A.; Rogers, Tony N.


    A linear solvation energy relationship has been found for 353 values of the limiting adsorption coefficients of diverse chemicals:  log K = −0.37 + 0.0341Vi − 1.07β + D + 0.65P with R = 0.951, s = 0.51, n = 353, and F = 818.0, where Vi is the intrinsic molar volume; β is a measure of the hydrogen bond acceptor strength of the solute; D is an index parameter for the research group which includes the effects of the different types of carbon used, the temperature, and the length of time allowed for the adsorption equilibrium to be established; and P is an index parameter for the flatness of the molecule. P is defined to be unity if there is an aromatic system in the molecule or if there is a double bond or series of conjugated double bonds with no more that one non-hydrogen atom beyond the double bond and zero otherwise. A slightly better fit is obtained if the two-thirds power of Vi is used as a measure of the surface area in place of the volume term:  log K = −1.75 + 0.227V2/3 − 1.10β + D + 0.60P with R = 0.954, s = 0.49, n = 353, and F = 895.39. This is the first quantitative measure of the effect of the shape of the molecule on its tendency to be adsorbed on activated carbon.

  18. Determination of solid-liquid partition coefficients (K{sub d}) for diazinon, propetamphos and cis-permethrin: implications for sheep dip disposal

    Cooke, Cindy M.; Shaw, George; Lester, John N.; Collins, Chris D


    Two groups of chemicals are currently licensed for use in sheep dip products in the UK. These are organophosphate (OP) insecticides and synthetic pyrethroid (SP) insecticides. SPs are deemed to be less toxic to human health than OPs, although they are approximately 100 times more toxic to some elements of the aquatic environment. Three insecticides were selected for experimental investigation: diazinon, propetamphos (OPs) and cis-permethrin (SP), representative of the active ingredients used in sheep dip formulations, with additional uses in insect control in crops, and for domestic control of flies, mosquitoes, cockroaches, lice, ticks and spiders. The UK Government has recently reviewed agricultural practices relating to the disposal of used sheep dip, because the constituent insecticides are frequently detected in UK watercourses and the presence of these compounds is a severe hazard to the aquatic environment. Standard batch sorption experiments were carried out to investigate insecticide partitioning from water to soil, and the relationship between sorption and soil organic carbon content is discussed. Sorption isotherms and K{sub d} values showed that cis-permethrin adsorption was fastest on all five soils investigated, exhibiting the greatest total partitioning to the soil phase (83.8-94.8%) and high resistance to desorption. In comparison, the OP insecticides exhibited moderately strong soil adsorption as evidenced by their K{sub d} coefficients (diazinon K{sub d} 12-35 and propetamphos K{sub d} 9-60), with low sorption reversibility (<15%). Calculation of a hydrological retardation factor in a scenario representative of a typical UK environment suggested that SP insecticides such as cis-permethrin will not migrate in the soil profile due to their virtual immobility and strong soil retention, and thus waste sheep dip disposal to agricultural land should not pose a risk to aquatic life if applied with appropriate controls.

  19. Distribution coefficients (Kd) of strontium and significance of oxides and organic matter in controlling its partitioning in coastal regions of Japan.

    Takata, Hyoe; Tagami, Keiko; Aono, Tatsuo; Uchida, Shigeo


    The Fukushima Daiichi Nuclear Power Plant accident in March 2011 resulted in the release of large quantities of a long-lived radioactive strontium (i.e. (90)Sr; half-life: 28.8 y) into the coastal areas of Japan. (90)Sr release was dispersed and mixed into the water column, and will eventually be deposited into sediment. Because factors controlling seawater-sediment partitioning in the coastal marine environments are not fully understood, we developed seawater-sediment distribution coefficients, Kd (L/kg), for Sr in coastal regions of Japan by means of sediment-water partitioning experiments. (85)Sr was used as a radiotracer and conditions were designed to mimic the environmental systems of the sampling sites as closely as possible. Experimentally determined Kd values (Kd-ex) varied between 0.3 and 3.3 L/kg (mean, 1.4 L/kg), and the variation in Kd-ex was attributed to the percentage of Sr in the exchangeable fraction in the sediment. Kd-ex values were used, along with the measured concentrations of (88)Sr, a stable naturally occurring Sr isotope in seawater and sediment, to estimate the concentrations of exchangeable Sr in the sediment. Estimates ranged from 2.1 to 24.3 μg/kg, or 1.3-15.7% of the total (88)Sr concentration in the sediment. Significant correlations existed between the estimated concentrations of exchangeable Sr, and the organic matter and the oxide/hydrous oxide contents. When organic contents were greater than 0.38%, Sr binds to organic surface sites more strongly than to the other sites. Results indicate that binding of Sr to the surface of sedimentary particles was influenced by grain size, iron and manganese oxides, and organic matter. Furthermore, the information presented here could be useful to estimate Kd values for anthropogenic (90)Sr in sediment in the coastal marine environment.

  20. Model sensitivity studies regarding the role of the retention coefficient for the scavenging and redistribution of highly soluble trace gases by deep convective cloud systems

    M. Salzmann


    Full Text Available The role of the retention coefficient (i.e. the fraction of a dissolved trace gas which is retained in hydrometeors during freezing for the scavenging and redistribution of highly soluble trace gases by deep convective cloud systems is investigated using a modified version of the Weather Research and Forecasting (WRF model. Results from cloud system resolving model runs (in which deep convection is initiated by small random perturbations in association with so-called "large scale forcings (LSF" for a tropical oceanic (TOGA COARE and a mid-latitude continental case (ARM are compared to two runs in which bubbles are used to initiate deep convection (STERAO, ARM. In the LSF runs, scavenging is found to almost entirely prevent a highly soluble tracer initially located in the lowest 1.5 km of the troposphere from reaching the upper troposphere, independent of the retention coefficient. The release of gases from freezing hydrometeors leads to mixing ratio increases in the upper troposphere comparable to those calculated for insoluble trace gases only in the two runs in which bubbles are used to initiate deep convection. A comparison of the two ARM runs indicates that using bubbles to initiate deep convection may result in an overestimate of the influence of the retention coefficient on the vertical transport of highly soluble tracers. It is, however, found that the retention coefficient plays an important role for the scavenging and redistribution of highly soluble trace gases with a (chemical source in the free troposphere and also for trace gases for which even relatively inefficient transport may be important. The large difference between LSF and bubble runs is attributed to differences in dynamics and microphysics in the inflow regions of the storms. The dependence of the results on the model setup indicates the need for additional model studies with a more realistic initiation of deep convection, e.g., considering effects of orography in a nested

  1. GEMAS: prediction of solid-solution partitioning coefficients (Kd) for cationic metals in soils using mid-infrared diffuse reflectance spectroscopy.

    Janik, Leslie J; Forrester, Sean T; Soriano-Disla, José M; Kirby, Jason K; McLaughlin, Michael J; Reimann, Clemens


    Partial least squares regression (PLSR) models, using mid-infrared (MIR) diffuse reflectance Fourier-transformed (DRIFT) spectra, were used to predict distribution coefficient (Kd) values for selected added soluble metal cations (Ag(+), Co(2+), Cu(2+), Mn(2+), Ni(2+), Pb(2+), Sn(4+), and Zn(2+)) in 4813 soils of the Geochemical Mapping of Agricultural Soils (GEMAS) program. For the development of the PLSR models, approximately 500 representative soils were selected based on the spectra, and Kd values were determined using a single-point soluble metal or radioactive isotope spike. The optimum models, using a combination of MIR-DRIFT spectra and soil pH, resulted in good predictions for log Kd+1 for Co, Mn, Ni, Pb, and Zn (R(2) ≥ 0.83) but poor predictions for Ag, Cu, and Sn (R(2)  Kd+1 values in the remaining 4313 unknown soils. The PLSR models provide a rapid and inexpensive tool to assess the mobility and potential availability of selected metallic cations in European soils. Further model development and validation will be needed to enable the prediction of log K(d+1) values in soils worldwide with different soil types and properties not covered in the existing model.

  2. Linear modeling of the soil-water partition coefficient normalized to organic carbon content by reversed-phase thin-layer chromatography.

    Andrić, Filip; Šegan, Sandra; Dramićanin, Aleksandra; Majstorović, Helena; Milojković-Opsenica, Dušanka


    Soil-water partition coefficient normalized to the organic carbon content (KOC) is one of the crucial properties influencing the fate of organic compounds in the environment. Chromatographic methods are well established alternative for direct sorption techniques used for KOC determination. The present work proposes reversed-phase thin-layer chromatography (RP-TLC) as a simpler, yet equally accurate method as officially recommended HPLC technique. Several TLC systems were studied including octadecyl-(RP18) and cyano-(CN) modified silica layers in combination with methanol-water and acetonitrile-water mixtures as mobile phases. In total 50 compounds of different molecular shape, size, and various ability to establish specific interactions were selected (phenols, beznodiazepines, triazine herbicides, and polyaromatic hydrocarbons). Calibration set of 29 compounds with known logKOC values determined by sorption experiments was used to build simple univariate calibrations, Principal Component Regression (PCR) and Partial Least Squares (PLS) models between logKOC and TLC retention parameters. Models exhibit good statistical performance, indicating that CN-layers contribute better to logKOC modeling than RP18-silica. The most promising TLC methods, officially recommended HPLC method, and four in silico estimation approaches have been compared by non-parametric Sum of Ranking Differences approach (SRD). The best estimations of logKOC values were achieved by simple univariate calibration of TLC retention data involving CN-silica layers and moderate content of methanol (40-50%v/v). They were ranked far well compared to the officially recommended HPLC method which was ranked in the middle. The worst estimates have been obtained from in silico computations based on octanol-water partition coefficient. Linear Solvation Energy Relationship study revealed that increased polarity of CN-layers over RP18 in combination with methanol-water mixtures is the key to better modeling of

  3. Simultaneous estimation of glass-water distribution and PDMS-water partition coefficients of hydrophobic organic compounds using simple batch method.

    Hsieh, Min-Kai; Fu, Chung-Te; Wu, Shian-chee


    A simple batch method by use of refilling and nonrefilling experimental procedures and headspace solid phase microextraction was applied to simultaneously obtain the glass-water distribution coefficients (K(GW)) and polydimethylsiloxane(PDMS)-water partition coefficients (K(PW)) of hydrophobic organic compounds (HOCs). The simple batch method takes into consideration the glass-surface bound HOCs and the corresponding equilibrium distribution of HOCs among the glass, water, headspace, and polydimethylsiloxane (PDMS). The K(PW) and K(GW) values of 53 PCB congeners were determined. The glass-bound fraction predominated over other fractions for highly chlorinated PCBs. Ignoring glass adsorption and assuming a complete mass balance could thus substantially underestimate the K(PW) for HOCs in traditional work. Good linear correlations of logα (the overall mass transfer rate constant) vs logK(PW), logK(PW) vs logK(OW), and logK(GW) vs logK(OW) were observed, with logα = -0.91 logK(PW) + 1.13, R(2) = 0.93; logK(PW) = 1.032 logK(OW) - 0.493, R(2) = 0.947; and logK(GW) = 0.93 logK(OW) - 2.30, R(2) = 0.90. The K(PW) values from this study were compared with those in the literature. With an account of the glass adsorption, the accuracy of the K(PW) determination and the estimation of the dissolved concentration in water for highly hydrophobic compounds can be significantly improved.

  4. Analysis of selected designer benzodiazepines by UHPLC with high-resolution time-of-flight mass spectrometry and the estimation of their partition coefficients by micellar electrokinetic chromatography.

    Tomková, Jana; Švidrnoch, Martin; Maier, Vítězslav; Ondra, Peter


    A new ultra high performance liquid chromatography with electrospray ionization time-of-flight mass spectrometry method for the selective and sensitive separation, identification and determination of selected designer benzodiazepines (namely, pyrazolam, phenazepam, etizolam, flubromazepam, diclazepam, deschloroetizolam, bentazepam, nimetazepam and flubromazolam) in human serum was developed. The separation of the studied designer benzodiazepines was achieved on C18 chromatographic column using gradient elution within 6 min without any significant matrix interferences. Liquid-liquid extraction with butyl acetate was applied for serum samples clean-up and preconcentration of studied designer benzodiazepines. The method was validated in terms of linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery and sample stability. The limit of detection values were in range 0.10-0.15 ng/mL. The method was applied on spiked serum sample to demonstrate its applicability for systematic toxicology analysis. Furthermore, a capillary chromatographic method with micellar electrokinetic chromatography was used for the estimation of partition coefficients of studied designer benzodiazepines as important parameters to evaluate their pharmacological and toxicological properties. This article is protected by copyright. All rights reserved.

  5. iLOGP: a simple, robust, and efficient description of n-octanol/water partition coefficient for drug design using the GB/SA approach.

    Daina, Antoine; Michielin, Olivier; Zoete, Vincent


    The n-octanol/water partition coefficient (log Po/w) is a key physicochemical parameter for drug discovery, design, and development. Here, we present a physics-based approach that shows a strong linear correlation between the computed solvation free energy in implicit solvents and the experimental log Po/w on a cleansed data set of more than 17,500 molecules. After internal validation by five-fold cross-validation and data randomization, the predictive power of the most interesting multiple linear model, based on two GB/SA parameters solely, was tested on two different external sets of molecules. On the Martel druglike test set, the predictive power of the best model (N = 706, r = 0.64, MAE = 1.18, and RMSE = 1.40) is similar to six well-established empirical methods. On the 17-drug test set, our model outperformed all compared empirical methodologies (N = 17, r = 0.94, MAE = 0.38, and RMSE = 0.52). The physical basis of our original GB/SA approach together with its predictive capacity, computational efficiency (1 to 2 s per molecule), and tridimensional molecular graphics capability lay the foundations for a promising predictor, the implicit log P method (iLOGP), to complement the portfolio of drug design tools developed and provided by the SIB Swiss Institute of Bioinformatics.

  6. Using molecular docking between organic chemicals and lipid membrane to revise the well known octanol-water partition coefficient of the mixture.

    Wang, Ting; Zhou, Xianghong; Wang, Dali; Yin, Daqiang; Lin, Zhifen


    The octanol-water partition coefficient of a mixture has been widely used to predict the baseline toxicity of non-polar narcotic chemical mixtures, since toxic effects are usually generated by multiple mixtures. However, it remains unclear whether the validity of log Kowmix can be demonstrated, because experimental methods cannot be used to determine this parameter. The invalidity and the further revision of log Kowmix were therefore studied by using molecular docking between non-polar narcotic chemicals and lipid membrane (E(binding)). The results show E(binding) is a feasible substitute parameter for log Kow because their relationship is linear. Based on a molecular docking and QSAR model, a new calculated method of log Kowmix was proposed as follows: log(Kowmix)=∑x(i)log Kowi. Comparison of this new method with the established methods demonstrates the invalidity of the latter, and therefore the former is suggested to be used to calculate the log Kowmix of organic chemical mixtures.

  7. Prediction of the air-water partition coefficient for perfluoro-2-methyl-3-pentanone using high-level Gaussian-4 composite theoretical methods.

    Rayne, Sierra; Forest, Kaya


    The air-water partition coefficient (Kaw) of perfluoro-2-methyl-3-pentanone (PFMP) was estimated using the G4MP2/G4 levels of theory and the SMD solvation model. A suite of 31 fluorinated compounds was employed to calibrate the theoretical method. Excellent agreement between experimental and directly calculated Kaw values was obtained for the calibration compounds. The PCM solvation model was found to yield unsatisfactory Kaw estimates for fluorinated compounds at both levels of theory. The HENRYWIN Kaw estimation program also exhibited poor Kaw prediction performance on the training set. Based on the resulting regression equation for the calibration compounds, the G4MP2-SMD method constrained the estimated Kaw of PFMP to the range 5-8 × 10(-6) M atm(-1). The magnitude of this Kaw range indicates almost all PFMP released into the atmosphere or near the land-atmosphere interface will reside in the gas phase, with only minor quantities dissolved in the aqueous phase as the parent compound and/or its hydrate/hydrate conjugate base. Following discharge into aqueous systems not at equilibrium with the atmosphere, significant quantities of PFMP will be present as the dissolved parent compound and/or its hydrate/hydrate conjugate base.

  8. Influence of bioassay volume, water column height, and octanol-water partition coefficient on the toxicity of pesticides to rainbow trout.

    Altinok, Ilhan; Capkin, Erol; Boran, Halis


    Effects of water volume and water column height on toxicity of cypermethrin, carbaryl, dichlorvos, tetradifon, maneb, captan, carbosulfan endosulfan and HgCl₂ to juvenile rainbow trout (Oncorhynchus mykiss, 3.2 ± 0.7 g) were evaluated in different glass aquaria under static conditions. When fish were exposed to the chemical compounds in 23 cm water column height (25 L), their mortality ranged between 0% and 58%. At the same water volume, but lower water column height (9 cm), mortality of fish increased significantly and was in a range from 60% to 95%. At the same water column height, toxic effects of chemicals were significantly higher in 25 L water volume than that of 8.5 L, water except maneb which has lowest (-0.45) octanol-water partition coefficient value. Mortality rates ratio of 9 and 23 cm water column height ranged between 1.12 and 90 while mortality rates ratio of 9 and 25 L water volume ranged between 1.20 and 4.0. Because actual exposure concentrations were not affected by either water volume or water column height, we propose that increased pesticides' toxicity was related to an increase in bioassay volume, since more pesticide molecules were able to interact with or accumulate the fish. However, there seem to be no relationship between the effects of water volume, water column height and Kow value of chemicals with regard to toxicity in juvenile rainbow trout.

  9. Potential of the octanol-water partition coefficient (logP) to predict the dermal penetration behaviour of amphiphilic compounds in aqueous solutions.

    Korinth, Gintautas; Wellner, Tanja; Schaller, Karl Heinz; Drexler, Hans


    Aqueous amphiphilic compounds may exhibit enhanced skin penetration compared with neat compounds. Conventional models do not predict this percutaneous penetration behaviour. We investigated the potential of the octanol-water partition coefficient (logP) to predict dermal fluxes for eight compounds applied neat and as 50% aqueous solutions in diffusion cell experiments using human skin. Data for seven other compounds were accessed from literature. In total, seven glycol ethers, three alcohols, two glycols, and three other chemicals were considered. Of these 15 compounds, 10 penetrated faster through the skin as aqueous solutions than as neat compounds. The other five compounds exhibited larger fluxes as neat applications. For 13 of the 15 compounds, a consistent relationship was identified between the percutaneous penetration behaviour and the logP. Compared with the neat applications, positive logP were associated with larger fluxes for eight of the diluted compounds, and negative logP were associated with smaller fluxes for five of the diluted compounds. Our study demonstrates that decreases or enhancements in dermal penetration upon aqueous dilution can be predicted for many compounds from the sign of logP (i.e., positive or negative). This approach may be suitable as a first approximation in risk assessments of dermal exposure.

  10. Mixed micelles of 7,12-dioxolithocholic acid and selected hydrophobic bile acids: interaction parameter, partition coefficient of nitrazepam and mixed micelles haemolytic potential.

    Poša, Mihalj; Tepavčević, Vesna


    The formation of mixed micelles built of 7,12-dioxolithocholic and the following hydrophobic bile acids was examined by conductometric method: cholic (C), deoxycholic (D), chenodeoxycholic (CD), 12-oxolithocholic (12-oxoL), 7-oxolithocholic (7-oxoL), ursodeoxycholic (UD) and hiodeoxycholic (HD). Interaction parameter (β) in the studied binary mixed micelles had negative value, suggesting synergism between micelle building units. Based on β value, the hydrophobic bile acids formed two groups: group I (C, D and CD) and group II (12-oxoL, 7-oxoL, UD and HD). Bile acids from group II had more negative β values than bile acids from group I. Also, bile acids from group II formed intermolecular hydrogen bonds in aggregates with both smaller (2) and higher (4) aggregation numbers, according to the analysis of their stereochemical (conformational) structures and possible structures of mixed micelles built of these bile acids and 7,12-dioxolithocholic acid. Haemolytic potential and partition coefficient of nitrazepam were higher in mixed micelles built of the more hydrophobic bile acids (C, D, CD) and 7,12-dioxolithocholic acid than in micelles built only of 7,12-dioxolithocholic acid. On the other hand, these mixed micelles still had lower values of haemolytic potential than micelles built of C, D or CD. The mixed micelles that included bile acids: 12-oxoL, 7-oxoL, UD or HD did not significantly differ from the micelles of 7,12-dioxolithocholic acid, observing the values of their haemolytic potential.

  11. Measurement of polyurethane foam - air partition coefficients for semivolatile organic compounds as a function of temperature: Application to passive air sampler monitoring.

    Francisco, Ana Paula; Harner, Tom; Eng, Anita


    Polyurethane foam - air partition coefficients (KPUF-air) for 9 polycyclic aromatic hydrocarbons (PAHs), 10 alkyl-substituted PAHs, 4 organochlorine pesticides (OCPs) and dibenzothiophene were measured as a function of temperature over the range 5 °C-35 °C, using a generator column approach. Enthalpies of PUF-to-air transfer (ΔHPUF-air, kJ/mol) were determined from the slopes of log KPUF-air versus 1000/T (K), and have an average value of 81.2 ± 7.03 kJ/mol. The log KPUF-air values at 22 °C ranged from 4.99 to 7.25. A relationship for log KPUF-air versus log KOA was shown to agree with a previous relationship based on only polychlorinated biphenyls (PCBs) and derived from long-term indoor uptake study experiments. The results also confirm that the existing KOA-based model for predicting log KPUF-air values is accurate. This new information is important in the derivation of uptake profiles and effective air sampling volumes for PUF disk samplers so that results can be reported in units of concentration in air. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  12. Polyparameter linear free energy models for polyacrylate fiber-water partition coefficients to evaluate the efficiency of solid-phase microextraction.

    Endo, Satoshi; Droge, Steven T J; Goss, Kai-Uwe


    The fiber-water partition coefficient, K(fw), is decisive for performance of solid-phase microextraction (SPME) techniques in organic chemical analyses. In this study, polyacrylate (PA)-coated fiber was evaluated for its K(fw) values toward diverse neutral organic compounds. Literature K(fw) data were thoroughly evaluated, and additional K(fw) values for 69 compounds were measured in phosphate-buffered saline (PBS) solution at 37 °C. These K(fw) data, spanning over 6 orders of magnitude, were used to construct polyparameter linear free energy relationship (PP-LFER) models. The PP-LFER models fit well to the data with a standard deviation of 0.15-0.23 log units. Additional experiments indicated that the differences in temperature (25 vs 37 °C), electrolyte concentrations (pure water vs PBS), and conditioning methods (heat vs methanol) had only minor influences (<0.3 log units) on K(fw). Using the established PP-LFERs, the SPME extraction efficiency of PA coating toward compounds of differing polarity was evaluated in comparison to poly(dimethylsiloxane) (PDMS) coating. PA exhibited higher extraction capacities for H-bond donor compounds (e.g., phenols, anilines, amides, and many drugs and pesticides) with the estimated K(fw) values being 1-4 log units higher than those of PDMS. Also, PA was shown to be more efficient than PDMS for hydrophobic aromatic compounds.

  13. Data and uncertainty assessment for radionuclide K{sub d} partitioning coefficients in granitic rock for use in SR-Can calculations

    Crawford, James; Neretnieks, Ivars; Malmstroem, Maria [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemical Engineering and Technology


    SKB is currently preparing licence applications related to the proposed deep repository for spent nuclear fuel as well as the encapsulation plant required for canister fabrication. The present report is one of several specific data reports that form the data input to an interim safety report (SR-Can) for the encapsulation plant licence application. This report concerns the derivation and recommendation of generic K{sub d} data (i.e. linear partitioning coefficients) for safety assessment modelling of far-field radionuclide transport in fractured granitic rock. The data are derived for typical Swedish groundwater conditions and rock types distinctive of those found on the Simpevarp peninsula and Forsmark. Data have been derived for 8 main elements (Cs, Sr, Ra, Ni, Th, U, Np, Am) and various oxidation states. The data have also been supplied with tentative correction factors to account for artefacts that have not been previously considered in detail in previous compilations. For the main reviewed solutes the data are given in terms of a best estimate K{sub d} value assumed to be the median of the aggregate set of selected data. A range corresponding to the 25-75% inter-quartile range is also specified and probable ranges of uncertainty are estimated in the form of an upper and lower limit to the expected variability. Data for an additional 19 elements that have not been reviewed are taken from a previous compilation by Carbol and Engkvist.

  14. Determination of n-octanol/water partition coefficient for DDT-related compounds by RP-HPLC with a novel dual-point retention time correction.

    Han, Shu-ying; Qiao, Jun-qin; Zhang, Yun-yang; Yang, Li-li; Lian, Hong-zhen; Ge, Xin; Chen, Hong-yuan


    n-Octanol/water partition coefficients (P) for DDTs and dicofol were determined by reversed-phase high performance liquid chromatography (RP-HPLC) on a C(18) column using methanol-water mixture as mobile phase. A dual-point retention time correction (DP-RTC) was proposed to rectify chromatographic retention time (t(R)) shift resulted from stationary phase aging. Based on this correction, the relationship between logP and logk(w), the logarithm of the retention factor extrapolated to pure water, was investigated for a set of 12 benzene homologues and DDT-related compounds with reliable experimental P as model compounds. A linear regression logP=(1.10±0.04) logk(w) - (0.60±0.17) was established with correlation coefficient R(2) of 0.988, cross-validated correlation coefficient R(cv)(2) of 0.983 and standard deviation (SD) of 0.156. This model was further validated using four verification compounds, naphthalene, biphenyl, 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD) and 2,2-bis(4-chlorophenyl)-1,1-dichloroethene (p,p'-DDE) with similar structure to DDT. The RP-HPLC-determined P values showed good consistency with shake-flask (SFM) or slow-stirring (SSM) results, especially for highly hydrophobic compounds with logP in the range of 4-7. Then, the P values for five DDT-related compounds, 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1,1-trichloroethane (o,p'-DDT), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethane (o,p'-DDD), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethene (o,p'-DDE), and 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol) and its main degradation product 4,4'-dichlorobenzophenone (p,p'-DBP) were evaluated by the improved RP-HPLC method for the first time. The excellent precision with SD less than 0.03 proved that the novel DP-RTC protocol can significantly increases the determination accuracy and reliability of P by RP-HPLC.

  15. ADME evaluation in drug discovery. 2. Prediction of partition coefficient by atom-additive approach based on atom-weighted solvent accessible surface areas.

    Hou, T J; Xu, X J


    A novel method for the calculations of 1-octanol/water partition coefficient (log P) of organic molecules has been presented here. The method, SLOGP v1.0, estimates the log P values by summing the contribution of atom-weighted solvent accessible surface areas (SASA) and correction factors. Altogether 100 atom/group types were used to classify atoms with different chemical environments, and two correlation factors were used to consider the intermolecular hydrophobic interactions and intramolecular hydrogen bonds. Coefficient values for 100 atom/group and two correction factors have been derived from a training set of 1850 compounds. The parametrization procedure for different kinds of atoms was performed as follows: first, the atoms in a molecule were defined to different atom/group types based on SMARTS language, and the correction factors were determined by substructure searching; then, SASA for each atom/group type was calculated and added; finally, multivariate linear regression analysis was applied to optimize the hydrophobic parameters for different atom/group types and correction factors in order to reproduce the experimental log P. The correlation based on the training set gives a model with the correlation coefficient (r) of 0.988, the standard deviation (SD) of 0.368 log units, and the absolute unsigned mean error of 0.261. Comparison of various procedures of log P calculations for the external test set of 138 organic compounds demonstrates that our method bears very good accuracy and is comparable or even better than the fragment-based approaches. Moreover, the atom-additive approach based on SASA was compared with the simple atom-additive approach based on the number of atoms. The calculated results show that the atom-additive approach based on SASA gives better predictions than the simple atom-additive one. Due to the connection between the molecular conformation and the molecular surface areas, the atom-additive model based on SASA may be a more

  16. Distribution coefficients (K{sub d}) of strontium and significance of oxides and organic matter in controlling its partitioning in coastal regions of Japan

    Takata, Hyoe, E-mail:; Tagami, Keiko; Aono, Tatsuo; Uchida, Shigeo


    The Fukushima Daiichi Nuclear Power Plant accident in March 2011 resulted in the release of large quantities of a long-lived radioactive strontium (i.e. {sup 90}Sr; half-life: 28.8 y) into the coastal areas of Japan. {sup 90}Sr release was dispersed and mixed into the water column, and will eventually be deposited into sediment. Because factors controlling seawater–sediment partitioning in the coastal marine environments are not fully understood, we developed seawater–sediment distribution coefficients, K{sub d} (L/kg), for Sr in coastal regions of Japan by means of sediment–water partitioning experiments. {sup 85}Sr was used as a radiotracer and conditions were designed to mimic the environmental systems of the sampling sites as closely as possible. Experimentally determined K{sub d} values (K{sub d-ex}) varied between 0.3 and 3.3 L/kg (mean, 1.4 L/kg), and the variation in K{sub d-ex} was attributed to the percentage of Sr in the exchangeable fraction in the sediment. K{sub d-ex} values were used, along with the measured concentrations of {sup 88}Sr, a stable naturally occurring Sr isotope in seawater and sediment, to estimate the concentrations of exchangeable Sr in the sediment. Estimates ranged from 2.1 to 24.3 μg/kg, or 1.3–15.7% of the total {sup 88}Sr concentration in the sediment. Significant correlations existed between the estimated concentrations of exchangeable Sr, and the organic matter and the oxide/hydrous oxide contents. When organic contents were greater than 0.38%, Sr binds to organic surface sites more strongly than to the other sites. Results indicate that binding of Sr to the surface of sedimentary particles was influenced by grain size, iron and manganese oxides, and organic matter. Furthermore, the information presented here could be useful to estimate K{sub d} values for anthropogenic {sup 90}Sr in sediment in the coastal marine environment. - Highlights: • K{sub d} for Sr were determined in Japanese coastal regions.

  17. Screening of pesticides for environmental partitioning tendency.

    Gramatica, Paola; Di Guardo, Antonio


    The partitioning tendency of chemicals, in this study pesticides in particular, into different environmental compartments depends mainly on the concurrent relevance of the physico-chemical properties of the chemical itself. To rank the pesticides according to their distribution tendencies in the different environmental compartments we propose a multivariate approach: the combination, by principal component analysis, of those physico-chemical properties like organic carbon partition coefficient (Koc), n-octanol/water partition coefficient (Kow), water solubility (Sw), vapour pressure and Henry's law constant (H) that are more relevant to the determination of environmental partitioning. The resultant macrovariables, the PC1 and PC2 scores here named leaching index (LIN) and volatality index (VIN), are proposed as preliminary environmental partitioning indexes in different media. These two indexes are modeled by theoretical molecular descriptors with satisfactory predictive power. Such an approach allows a rapid pre-determination and screening of the environmental distribution of pesticides starting only from the molecular structure of the pesticide, without any a priori knowledge of the physico-chemical properties.

  18. Chlorine and fluorine partition coefficients and abundances in sub-arc mantle xenoliths (Kamchatka, Russia): Implications for melt generation and volatile recycling processes in subduction zones

    Bénard, A.; Koga, K. T.; Shimizu, N.; Kendrick, M. A.; Ionov, D. A.; Nebel, O.; Arculus, R. J.


    We report chlorine (Cl) and fluorine (F) abundances in minerals, interstitial glasses, and melt inclusions in 12 andesite-hosted, spinel harzburgite xenoliths and crosscutting pyroxenite veins exhumed from the sub-arc lithospheric mantle beneath Avacha volcano in the Kamchatka Arc (NE Russia). The data are used to calculate equilibrium mineral-melt partition coefficients (D mineral / melt) for Cl and F relevant to subduction-zone processes and unravel the history of volatile depletion and enrichment mechanisms in an arc setting. Chlorine is ∼100 times more incompatible in pyroxenes (DClmineral/melt = 0.005-0.008 [±0.002-0.003]) than F (DFmineral/melt = 0.50-0.57 [±0.21-0.24]), which indicates that partial melting of mantle sources leads to strong depletions in Cl relative to F in the residues. The data set in this study suggests a strong control of melt composition on DCl,Fpyroxene/melt, in particular H2O contents and Al/(Al + Si), which is in line with recent experiments. Fluorine is compatible in Ca-amphibole in the 'wet' sub-arc mantle (DFamphibole/melt = 3.5-3.7 [±1.5]) but not Cl (DClamphibole/melt = 0.03-0.05 [±0.01-0.03]), indicating that amphibole may fractionate F from Cl in the mantle wedge. The inter-mineral partition coefficients for Cl and F in this study are consistent amongst different harzburgite samples, whether they contain glass or not. In particular, disseminated amphibole hosts much of the Cl and F bulk rock budgets of spinel harzburgites (DClamphibole/pyroxene up to 14 and DFamphibole/pyroxene up to 40). Chlorine and fluorine are variably enriched (up to 1500 ppm Cl and 750 ppm F) in the parental arc picrite and boninite melts of primitive pyroxenite veins (and related melt inclusions) crosscutting spinel harzburgites. Based on the data in this study, the main inferences on the behaviour of Cl and F during melting and metasomatic processes in the sub-arc mantle are as follow: (i) Melting models show that most depleted mantle protoliths

  19. Development of a decision tree to classify the most accurate tissue-specific tissue to plasma partition coefficient algorithm for a given compound.

    Yun, Yejin Esther; Cotton, Cecilia A; Edginton, Andrea N


    Physiologically based pharmacokinetic (PBPK) modeling is a tool used in drug discovery and human health risk assessment. PBPK models are mathematical representations of the anatomy, physiology and biochemistry of an organism and are used to predict a drug's pharmacokinetics in various situations. Tissue to plasma partition coefficients (Kp), key PBPK model parameters, define the steady-state concentration differential between tissue and plasma and are used to predict the volume of distribution. The experimental determination of these parameters once limited the development of PBPK models; however, in silico prediction methods were introduced to overcome this issue. The developed algorithms vary in input parameters and prediction accuracy, and none are considered standard, warranting further research. In this study, a novel decision-tree-based Kp prediction method was developed using six previously published algorithms. The aim of the developed classifier was to identify the most accurate tissue-specific Kp prediction algorithm for a new drug. A dataset consisting of 122 drugs was used to train the classifier and identify the most accurate Kp prediction algorithm for a certain physicochemical space. Three versions of tissue-specific classifiers were developed and were dependent on the necessary inputs. The use of the classifier resulted in a better prediction accuracy than that of any single Kp prediction algorithm for all tissues, the current mode of use in PBPK model building. Because built-in estimation equations for those input parameters are not necessarily available, this Kp prediction tool will provide Kp prediction when only limited input parameters are available. The presented innovative method will improve tissue distribution prediction accuracy, thus enhancing the confidence in PBPK modeling outputs.

  20. Hepatocyte composition-based model as a mechanistic tool for predicting the cell suspension: aqueous phase partition coefficient of drugs in in vitro metabolic studies.

    Poulin, Patrick; Haddad, Sami


    This study is an extension of a previously published microsome composition-based model by Poulin and Haddad (Poulin and Haddad. 2011. J Pharm Sci 100:4501-4517), which was converted to the hepatocyte composition-based model. The first objective was to investigate the ability of the composition-based model to predict nonspecific binding of drugs in hepatocytes suspended in the incubation medium in in vitro metabolic studies. The hepatocyte composition-based model describes the cell suspension-aqueous phase partition coefficients, which were used to estimate fraction unbound in the incubation medium (fuinc ) for each drug. The second objective was to make a comparative analysis between the proposed hepatocyte composition-based model and an empirical regression equation published in the literature by Austin et al. (Austin RP, Barton P, Mohmed S, Riley RJ. 2004. Drug Metab Dispos 33:419-425). The assessment was confined by the availability of experimentally determined in vitro fuinc values at diverse hepatocyte concentrations for 92 drugs. The model that made use of hepatocyte composition data provides comparable or superior prediction performance compared with the regression equation that relied solely on physicochemical data; therefore, this demonstrates the ability of predicting fuinc also based on mechanisms of drug tissue distribution. The accuracy of the predictions differed depending on the class of drugs (neutrals vs. ionized drugs) and species (rat vs. human) for each method. This study for hepatocytes corroborates a previous study for microsomes. Overall, this work represents a significant first step toward the development of a generic and mechanistic calculation method of fuinc in incubations of hepatocytes, which should facilitate rational interindividual and interspecies extrapolations of fuinc by considering differences in lipid composition of hepatocytes, for clearance prediction in the physiologically-based pharmacokinetics (PBPK) models.

  1. Solid/liquid partition coefficients (K{sub d}) and plant/soil concentration ratios (CR) for selected soils, tills and sediments at Forsmark

    Sheppard, Steve (ECOMatters Inc. (Canada)); Sohlenius, Gustav (Sveriges geologiska undersoekning (Sweden)); Omberg, Lars-Gunnar (ALS Scandinavia AB (Sweden)); Borgiel, Mikael (Sveriges Vattenekologer AB (Sweden)); Grolander, Sara (Facilia AB (Sweden)); Norden, Sara (Svensk Kaernbraenslehantering AB (Sweden))


    Solid/liquid partition coefficients (K{sub d}) are used to indicate the relative mobility of radionuclides and elements of concern from nuclear fuel waste, as well as from other sources. To indicate the uptake of radionuclides in biota concentration ratios (CR) between soil and biota are used. This report summarized K{sub d} data for regolith and marine sediments based on concentrations of 69 indigenous stable elements measured from samples collected at the Forsmark site and CR data concerning cereals growing on these soils. The samples included 50 regolith samples from agricultural land and wetlands, 8 samples of till collected at different depths, and two marine sediment samples. In addition, cereal grains, stems and roots were collected from 4 sites for calculation of CRs. The regolith samples represented the major 5 deposits, which can be used as arable land, at the site (clayey till, glacial clay, clay gyttja and peat (cultivated and undisturbed)). K{sub d} values were generally lower for peat compared to clay soils. There were also clear differences in K{sub d} resulting from differences in soil chemistry within each regolith type. Soil pH was the most important factor, and K{sub d} values for many elements were lower in acidic clay soils compared to basic clay soils. Although there were only a few samples of sandy till and marine sediment, the K{sub d} values were generally consistent with the corresponding regolith K{sub d} values. Of the different cereal parts the grain always had the lowest CR. In most cases, the root CR was significantly higher than the grain CR, whereas only for a few elements were the grain and stem CR values different

  2. 莫索尼定的电离常数和分配系数的测定%The determination of the ionization constant and partition coefficient of moxonidine

    张远杏; 武凤兰; 李玉珍


    The methods were described for determining the ionizationconstant and partition coefficient of moxonidine. The ionization constant was determined by the potential titration method,and the pKTa was 7.35±0.03.The partition coefficient was determined by the bottle-shaking method,and the P=12.02±0.13.%在25℃下,分别测定了莫索尼定的电离常数和分配系数。采用电位滴定法测得莫索尼定的电离常数pKTa值为7.35±0.03。采用摇瓶法测得莫索尼定的分配系数为P=12.02±0.13。

  3. Improved models for the prediction of activity coefficients in nearly athermal mixtures .2. A theoretically-based G(E)-model based on the van der Waals partition function

    Kontogeorgis, Georgios; Georgios, Nikolopoulos; Fredenslund, Aage


    of the generalized van der Waals partition function and attempts to account for all non-energetic effects of solutions of both short- and long-chain alkanes, including alkane polymers. Both the free-volume effects and the density-dependent rotational degrees of freedom are considered. The resulting G(E)-model which......, despite its derivation from a partition function resembles the Flory-Huggins formula, is suitable for vapor-liquid and solid-liquid equilibrium calculations for nearly athermal polymer solutions as well as for alkane systems. We show that using plausible assumptions for the free-volume and the external......-degree-of-freedom parameter, very good predictions are obtained for activity coefficients of asymmetric alkane systems at both concentration ends, for solid-liquid equilibrium calculations, as well as in extreme cases (polymer solutions, activity coefficients of heavy model alkane polymers in short-chain compounds recently...

  4. Synchrotron Micro-XANES Measurements of Vanadium Oxidation State in Glasses as a Function of Oxygen Fugacity: Experimental Calibration of Data Relevant to Partition Coefficient Determination

    Delaney, J. S.; Sutton, S. R.; Newville, M.; Jones, J. H.; Hanson, B.; Dyar, M. D.; Schreiber, H.


    Oxidation state microanalyses for V in glass have been made by calibrating XANES spectral features with optical spectroscopic measurements. The oxidation state change with fugacity of O2 will strongly influence partitioning results.

  5. Element composition of biota, water and sediment in the Forsmark area, Baltic Sea. Concentrations, bioconcentration factors and partitioning coefficients (K{sub d}) of 48 elements

    Kumblad, Linda; Bradshaw, Clare (Dept. of Systems Ecology, Stockholm Univ. (Sweden))


    In this study the elemental composition of biota, water and sediment from a shallow bay in the Forsmark region have been determined. The report presents data for 48 different elements (Al, As, Ba, Br, C, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Gd, Hg, Ho, I, K, Li, Lu, Mg, Mn, N, Na, Nd, Ni, P, Pb, Pr, Ra, Rb, S, Se, Si, Sm, Tb, Th, Ti, Tm, V, Yb, Zn, Zr) in all major functional groups of the coastal ecosystem (phytoplankton, zooplankton, benthic microalgae, macroalgae, macrophytes, benthic herbivores, benthic filter feeders, benthic detrivores, planktivorous fish, benthic omnivorous fish, carnivorous fish, dissolved and particulate matter in the water and the sediment) during spring 2005. The overall aim of the study is to contribute to a better understanding of ecological properties and processes that govern uptake and transfer of trace elements, heavy-metals, radionuclides and other non-essential elements/contaminants in coastal environments of the Baltic Sea. In addition, the data was collected to provide site-specific Bioconcentration Factors (BCF), Biomagnification Factors (BMF), partitioning coefficients (K{sub d}) and element ratios (relative to carbon) for use in ongoing SKB safety assessments. All these values, as well as the element concentration data from which they are derived, are presented here. As such, this is mainly a data report, although initial interpretations of the data also are presented and discussed. Reported data include element concentrations, CNP-stoichiometry, and multivariate data analysis. Elemental concentrations varied greatly between organisms and environmental components, depending on the function of the elements, and the habitat, ecosystem function, trophic level and morphology (taxonomy) of the organisms. The results show for instance that food intake and metabolism strongly influence the elemental composition of organisms. The three macrophytes had quite similar elemental composition (despite their taxonomic

  6. Quantification of surface area and intrinsic mass transfer coefficient for ultrasound-assisted dissolution process of a sparingly soluble solid dispersed in aqueous solutions.

    Durbha, Krishna Sandilya; Aravamudan, Kannan


    The efficacy of power ultrasound of 20 kHz in enhancing the volumetric mass transfer coefficient was investigated in this study. Breakage and dissolution of sparingly soluble benzoic acid dispersed in either water or 24% aqueous glycerol was monitored as a function of time and ultrasound power input. Particle size measurements were carried out at intermediate times during the experiment to estimate the mean particle size and surface area. Linear combination of lognormal distributions was found to fit the experimental particle size distribution data. The De Brouckere mean diameters (d(43)) obtained from the particle size distributions decreased with increase in the ultrasonic power level. Empirical correlations were developed for the evolution of surface area as a function of ultrasonic energy input per unit mass. The effect of ultrasound on the intrinsic mass transfer coefficient (k(c)) could be decoupled from the volumetric mass transfer coefficient (k(c)a) as the surface area was also estimated. Different approaches involving either constant or variable intrinsic mass transfer coefficients were employed when carrying out the delineation. Mass transfer rates were enhanced due to both higher ultrasound induced intrinsic convective mass transfer coefficient and additional surface area created from particle breakage. To delineate the effects of particle breakage from solid dissolution, experiments were also carried out under non-mass transfer conditions by pre-saturating the solvents with benzoic acid. Both the solid-liquid systems examined in the present study attained saturation concentration when the ultrasonic energy input per unit mass was approximately 60 kJ/kg, irrespective of the ultrasonic power level setting.

  7. 丁香苦苷解离常数及油水分配系数的测定%Determination of Dissociation Constants and Apparent OiL/Water Partition Coefficient of Syringopicroside

    曹颖; 李永吉; 吕邵娃; 王艳宏


    Objective: To determine the dissociation constants of syringopicroside and its partition coefficients for the n-octanol-water/buffer solution systems. Method: To determine the dissociation constants of syringopicroside were determined by UV-visible spectrophotometer, at the same time, the partition coefficients in the n-octanol-water /buffer solution systems of syringopicroside were determined by shaking flask method. Result; The pka value is 9.628 4 ± 0. 14, and the n-octanol/water partition coefficient Papp is 1.206 9 (logPapp =0.081 7). When the pH is 4. 5 , 5. 5 , 6. 5 , 7. 5 , 8. 5 , the n-octanol/water partition coefficient Papp is 1. 388 1, 1. 352 9, 1.335 8,1.370 4,1.133 3 respectively, indicating that there is little effect on the n-octanol/water partition coefficient of syringopicroside in different pH values buffer solution. Conclusion; In the physiological environment, drugs most existed as most molecular state. The syringopicroside has good hydrophilicity, but poor liposolubility, it maybe affect the absorption, distribution of syringopicroside and the design of dosage forms.%目的:测定丁香苦苷解离常数和油水分配系数.方法:采用紫外分光光度法,测得丁香苦苷解离常数,应用HPLC测定丁香苦苷的表观正辛醇/水分配系数.结果:丁香苦苷解离常数pKa为9.6284±0.14.油水分配系数Papp为1.2069(logPapp=0.0817),当pH 4.5,5.5,6.5,7.5,8 5时,油水分配系数Papp分别为1.3881,1.3529,1.3358,1.3704,1.133 3,表明丁香苦苷的表观正辛醇/缓冲溶液分配系数受缓冲溶液pH的影响不大.结论:在生理pH下,丁香苦苷大部分以未解离的分子状态存在,但丁香苦苷水溶性好,脂溶性较差,可能会对丁香苦苷的吸收分布及设计药物剂型产生影响.

  8. A strategy for the separation of diterpenoid isomers from the root of Aralia continentalis by countercurrent chromatography: The distribution ratio as a substitute for the partition coefficient and a three-phase solvent system.

    Lee, Kyoung Jin; Song, Kwang Ho; Choi, Wonmin; Kim, Yeong Shik


    Aralia continentalis (Araliaceae) is widely used as a medicinal plant in East Asia. Previous studies have indicated that diterpenoid isomers (kaurenoic acid, continentalic acid, and ent-continentalic acid) are the major bioactive compounds of this plant. A new strategy was developed to alleviate difficulties in the separation of these isomers from this plant. A three-phase solvent system was applied to separate the isomers, and furthermore, the distribution ratio (Kc) was introduced as a substitute for the partition coefficient (KD). For compounds exhibiting a single equilibrium, their distributions in two immiscible phases were only affected by the partition coefficient of each solute. However, compounds that have a dissociating functional group (e.g., -COOH) are involved in two types of equilibrium in the two-phase system. In this case, the partitioning behaviors of the solutes are greatly affected by the pH of the solution. A mathematical prediction was applied for adjusting the solutions to the proper pH values. To prevent non-used phase (medium phase) waste, both the stationary phase (upper phase) and mobile phase (lower phase) were prepared on-demand without pre-saturation with the application of (1)H NMR. Each fraction obtained was collected and dried, yielding the following diterpenoid isomers from the 50mg injected sample: kaurenoic acid (19.7mg, yield: 39%) and ent-continentalic acid (21.3mg, yield: 42%).

  9. Estimation of partition, free and specific diffusion coefficients of paclitaxel and taxanes in a fixed bed by moment analysis: experimental, modeling and simulation studies - doi: 10.4025/actascitechnol.v34i1.8060

    Marco Aurélio Cremasco


    Full Text Available Paclitaxel, as known Taxol®, is an important agent in cancer treatment, founded in mixture with many structural analogs, or taxanes, present in natural source or plant tissue culture broth. The adsorption techniques are used in the purification of placlitaxel from that complex mixture, but despite of the strategy it is important to know the basic parameters associated with any process, such as isotherms and mass transfer parameters. In this paper is presented a simple model to estimate these parameters by moment analysis. After to consider linear isotherm for adsorption, the partition coefficient, free and effective diffusion coefficients of paclitaxel and four major components, in a plant tissue culture broth, were estimated from the first and second moments of peaks in pulse-elution chromatograms. The experimental chromatograms at two flow rates are compared with those ones from model, also proposed in this work. The experimental results of free diffusion coefficient are compared with that ones from the Literature.

  10. Measurements of octanol-air partition coefficients, vapor pressures and vaporization enthalpies of the (E) and (Z) isomers of the 2-ethylhexyl 4-methoxycinnamate as parameters of environmental impact assessment.

    Pegoraro, César N; Chiappero, Malisa S; Montejano, Hernán A


    2-Ethylhexyl 4-methoxycinnamate is one of the UVB blocking agents more widely used in a variety of industrial fields. There are more than one hundred industrial suppliers worldwide. Given the enormous annual consumption of octinoxate, problems that arise due to the accumulation of this compound in nature should be taken into consideration. The GC-RT was used in this work with the aim of determining the vapor pressure, enthalpies of vaporization and octanol-air partition coefficient, for the BBP, DOP, E- and Z-EHMC esters. The results showed that Z-EHMC is almost five times more volatile than E-EHMC. Moreover, BBP, Z-EHMC and E-EHMC can be classified as substances with a relatively low mobility since they lie within the range of 810 and log(PL/Pa)<-4, therefore, a low mobility can be expected. From these parameters, their particle-bound fraction and gas-particle partition coefficient were also derived. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Chromatographic retention prediction and octanol-water partition coefficient determination of monobasic weak acidic compounds in ion-suppression reversed-phase liquid chromatography using acids as ion-suppressors.

    Ming, Xin; Han, Shu-ying; Qi, Zheng-chun; Sheng, Dong; Lian, Hong-zhen


    Although simple acids, replacing buffers, have been widely applied to suppress the ionization of weakly ionizable acidic analytes in reversed-phase liquid chromatography (RPLC), none of the previously reported works focused on the systematic studies about the retention behavior of the acidic solutes in this ion-suppression RPLC mode. The subject of this paper was therefore to investigate the retention behavior of monobasic weak acidic compounds using acetic, perchloric and phosphoric acids as the ion-suppressors. The apparent octanol-water partition coefficient (K" ow) was proposed to calibrate the octanol-water partition coefficient (K(ow)) of these weak acidic compounds, which resulted in a better linear correlation with log k(w), the logarithm of the hypothetical retention factor corresponding to neat aqueous fraction of hydroorganic mobile phase. This log K" ow-log k w linear correlation was successfully validated by the results of monocarboxylic acids and monohydrating phenols, and moreover by the results under diverse experimental conditions for the same solutes. This straightforward relationship not only can be used to effectively predict the retention values of weak acidic solutes combined with Snyder-Soczewinski equation, but also can offer a promising medium for directly measuring K(ow) data of these compounds via Collander equation. In addition, the influence of the different ion-suppressors on the retention of weak acidic compounds was also compared in this RPLC mode.

  12. The Effect of Changes in Acidity and Salinity on the Octanol Water Partition Coefficient of Monomethylmercuric Species Present in Aquatic Environments at High pE.


    Wiley & Sons. 3. Manahan , S.E. 1990. Environmental Chemistry . 4th ed. Chelsea, MI: Lewis Publishers, Inc. 4. Hem, J.D. 1970. Chemical behavior of... environmental monomethylmercury exists primarily as methylmercuric chloride and methylmercuric hydroxide. The carbon-mercury bond is stable in methylmercury...between 1-octanol and water (Kow) is important to environmental research. Such values can be used in predictive models to estimate solubility, transport

  13. Substituent effect on the thermodynamic solubility of structural analogs: relative contribution of crystal packing and hydration.

    Ozaki, Shunsuke; Nakagawa, Yoshiaki; Shirai, Osamu; Kano, Kenji


    Thermodynamic analysis of the solubility of benzoylphenylurea (BPU) derivatives was conducted to investigate the relative importance of crystal packing and hydration for improving solubility with minor structural modification. The contribution of crystal packing to solubility was evaluated from the change in Gibbs energy on the transition from the crystalline to liquid state. Hydration Gibbs energy was estimated using a linear free-energy relationship between octanol-water partition coefficients and gas-water partition coefficients. The established solubility model satisfactorily explained the relative thermodynamic solubility of the model compounds and revealed that crystal packing and hydration equally controlled solubility of the structural analogs. All hydrophobic substituents were undesirable for solubility in terms of hydration, as expected. On the other hand, some of these hydrophobic substituents destabilized crystal packing and improved the solubility of the BPU derivatives when their impact on crystal packing exceeded their negative influence on hydration. The replacement of a single substituent could cause more than a 10-fold enhancement in thermodynamic solubility; this degree of improvement was comparable to that generally achieved by amorphous formulations. Detailed analysis of thermodynamic solubility will allow us to better understand the true substituent effect and design drug-like candidates efficiently.

  14. Partition of polycyclic aromatic hydrocarbons on organobentonites


    A series of organobentonites synthesized by exchanging organiccation such as dodecyltri-methylammonium (DTMA),benzyldimethyltetradecylammonium (BDTDA), cetyltrimethyl-ammonium (CTMA), octodeyltrimethylammonium (OTMA) on bentonite. The optimal condition, properties and mechanisms for the organobentonites to sorb phenanthrene, anthracene, naphthalene, acenaphthene in water were investigated in detail. The partition behavior was determined for four polycyclic aromatic hydrocarbons (PAHs), such as naphthalene, phenanthrene, anthracene and acenaphthene, from water to a series of organobentonites. The interlayer spacings and organic carbon contents of organobentonites, removal rate and sorption capacities for organobentonites to treat phenanthrene,anthracene, naphthalene, acenaphthene were correlated to the length of alkyl chains and the amounts of cation surfactant exchanged on Foundation item: the bentonite. Phenanthrene, anthracene, naphthalene, and acenaphthene sorption to organobentonites were characterized by linear isotherms, indicating solute partition between water and the organic phase composed of the large alkyl functional groups of quaternary ammonium cations. PAHs distribution coefficients (Kd)between organobentonites and water were proportional to the organic carbon contents of organobentonites. However, the partition coefficients (Koc) were nearly constants for PAHs in the system of organobentonite-water. The Koc of phenanthrene, anthracene,naphthalene, acenaphthene were 2.621x105, 2.106x105, 2.247x104,5.085x104, respectively. The means Koc values on the organobentonites are about ten to twenty times larger than the values on the soils/sediments, what is significant prerequisite for organobentonite to apply to remediation of pollution soil and groundwater. The sorption mechanism was also evaluated from octanol-water partition coefficients and aqueous solubility of PAHs. The correlations between lgKoc and 1gkow, 1gKoc and 1gS for PAHs in the system of water

  15. Air-Liquid Partition Coefficient for a Diverse Set of Organic Compounds: Henry’s Law Constant in Water and Hexadecane

    The SPARC vapor pressure and activity coefficient models were coupled to estimate Henry’s Law Constant (HLC) in water and in hexadecane for a wide range of non-polar and polar solute organic compounds without modification to/or additional parameterization of the vapor pressure or...

  16. Buffer nitrogen solubility, in vitro ruminal partitioning of nitrogen and in vitro ruminal biological activity of tannins in leaves of four fodder tree species.

    Cudjoe, N; Mlambo, V


    This study explores the chemical composition, buffer N solubility, in vitro ruminal N degradability and in vitro ruminal biological activity of tannins in leaves from Gliricidia sepium, Leucaena leucocephala, Morus alba and Trichanthera gigantea trees. These tree leaves are a potential protein source for ruminants, but their site-influenced nutritive value is largely unknown. Leucaena leucocephala leaves had the highest N content (42.1 g/kg DM), while T. gigantea leaves had the least (26.1 g/kg DM). Leucaena leucocephala had the highest buffer solubility index (20%), while 10% of the total N in leaves of the other three species was soluble. The rapidly fermentable N fraction 'a' was highest in M. alba leaves (734.9 g/kg DM) and least in T. gigantea leaves (139.5 g/kg DM). The rate of fermentation (c) was highest for M. alba (7%/hours) leaves. No significant correlations were recorded between buffer solubility index of N and in vitro ruminal N degradability parameters: a, b, and c. The highest response to tannin inactivation using polyethylene glycol, in terms of percentage increase in 36-hours cumulative gas production, was recorded in M. alba (39%) and T. gigantea (38%) leaves. It was concluded that buffer solubility of N is not a good indicator of ruminal N degradation in the leaves of these tree species. Leaves of M. alba could be more valuable as a source of rapidly fermentable N when animals are offered low-protein, high-fibre diets compared with other tree species evaluated in the current study. However, when feeding M. alba leaves, the role of tannins must be considered because these secondary plant compounds showed significant in vitro ruminal biological activity.

  17. Coding Partitions

    Fabio Burderi


    Full Text Available Motivated by the study of decipherability conditions for codes weaker than Unique Decipherability (UD, we introduce the notion of coding partition. Such a notion generalizes that of UD code and, for codes that are not UD, allows to recover the ``unique decipherability" at the level of the classes of the partition. By tacking into account the natural order between the partitions, we define the characteristic partition of a code X as the finest coding partition of X. This leads to introduce the canonical decomposition of a code in at most one unambiguouscomponent and other (if any totally ambiguouscomponents. In the case the code is finite, we give an algorithm for computing its canonical partition. This, in particular, allows to decide whether a given partition of a finite code X is a coding partition. This last problem is then approached in the case the code is a rational set. We prove its decidability under the hypothesis that the partition contains a finite number of classes and each class is a rational set. Moreover we conjecture that the canonical partition satisfies such a hypothesis. Finally we consider also some relationships between coding partitions and varieties of codes.

  18. Estimation of Octanol-Water Partition Coefficient of Chloride Hydrocarbon by Group Contribution Method%基团贡献法估算氯代化合物正辛醇-水分配系数

    梁英华; 陈红萍


    A novel method named two-level group contribution (GC-K) method for the estimation of octanol-water partition coefficient (Kow) of chloride hydrocarbon is presented. The equation includes only normal boiling points and molecular weight of compounds. Group contribution parameters of 12 first-level groups and 7 second-level groups for Kow are obtained by correlating experimental data of three types including 57 compounds. By comparing the estimation results of the first-level with that of the two-level groups, it was observed that the latter is better with the addition of the modification of proximity effects. When compared with Marrero's three-level group contribution approach and atom-fragment contribution method (AFC), the accuracy of the average relative error of GC-K by first-level groups is 7.20% and is preferred to other methods.

  19. Effects of polar and nonpolar groups on the solubility of organic compounds in soil organic matter

    Chiou, C.T.; Kile, D.E.


    Vapor sorption capacities on a high-organic-content peat, a model for soil organic matter (SOM), were determined at room temperature for the following liquids: n-hexane, 1,4-dioxane, nitroethane, acetone, acetonitrile, 1-propanol, ethanol, and methanol. The linear organic vapor sorption is in keeping with the dominance of vapor partition in peat SOM. These data and similar results of carbon tetrachloride (CT), trichloroethylene (TCE), benzene, ethylene glycol monoethyl ether (EGME), and water on the same peat from earlier studies are used to evaluate the effect of polarity on the vapor partition in SOM. The extrapolated liquid solubility from the vapor isotherm increases sharply from 3-6 wt % for low-polarity liquids (hexane, CT, and benzene) to 62 wt % for polar methanol and correlates positively with the liquid's component solubility parameters for polar interaction (??P) and hydrogen bonding (??h). The same polarity effect may be expected to influence the relative solubilities of a variety of contaminants in SOM and, therefore, the relative deviations between the SOM-water partition coefficients (Kom) and corresponding octanol-water partition coefficients (Kow) for different classes of compounds. The large solubility disparity in SOM between polar and nonpolar solutes suggests that the accurate prediction of Kom from Kow or Sw (solute water solubility) would be limited to compounds of similar polarity.

  20. Determination of polydimethylsiloxane–water partition coefficients for ten 1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl)ethyl]benzene-related compounds and twelve polychlorinated biphenyls using gas chromatography/mass spectrometry

    Eganhouse, Robert P.


    Polymer-water partition coefficients (Kpw) of ten DDT-related compounds were determined in pure water at 25 °C using commercial polydimethylsiloxane-coated optical fiber. Analyte concentrations were measured by thermal desorption-gas chromatography/full scan mass spectrometry (TD–GC/MSFS; fibers) and liquid injection-gas chromatography/selected ion monitoring mass spectrometry (LI–GC/MSSIM; water). Equilibrium was approached from two directions (fiber uptake and depletion) as a means of assessing data concordance. Measured compound-specific log Kpw values ranged from 4.8 to 6.1 with an average difference in log Kpw between the two approaches of 0.05 log units (∼12% of Kpw). Comparison of the experimentally-determined log Kpw values with previously published data confirmed the consistency of the results and the reliability of the method. A second experiment was conducted with the same ten DDT-related compounds and twelve selected PCB (polychlorinated biphenyl) congeners under conditions characteristic of a coastal marine field site (viz., seawater, 11 °C) that is currently under investigation for DDT and PCB contamination. Equilibration at lower temperature and higher ionic strength resulted in an increase in log Kpw for the DDT-related compounds of 0.28–0.49 log units (61–101% of Kpw), depending on the analyte. The increase in Kpw would have the effect of reducing by approximately half the calculated freely dissolved pore-water concentrations (Cfree). This demonstrates the importance of determining partition coefficients under conditions as they exist in the field.

  1. Determination and estimation of partitioning properties for substituted phosphates and thiophosphates.

    Dong, Yuying; Ding, Guanghui; Cao, Ying; Wang, Zhuang; Sun, Cheng


    Substituted phenylglyoxylonitrile oximino phosphates and thiophosphates invested as a synergist of molluscicide killing snail eggs have been exposed to the environment with very little attention. The partitioning properties, aqueous solubility (S(w)), n-octanol-water partition coefficient (K(ow)) and soil organic carbon sorption coefficients (K(oc)) of 16 O, O'-dialkyl, O''-(substituted phenylglyoxylonitrile oximino) phosphates and thiophosphates, were determined by the traditional shaking flask method. The parameters of molecular fragment connectivity indices (MFCIs) and linear solvation energy relationships (LSERs) were used as molecular descriptors to establish a series of correlation equations successfully. The obtained correlation equations provided a quantitative method to predict the three partitioning properties for new exploited substituted phosphates and thiophosphates. More valuable, the successful application of MFCIs provides us with a good example and a good idea to improve traditional molecular connectivity indices (MCIs).

  2. Partitioning of the Suspended Particulate Spectral Scattering Coefficient in Poyang Lake%鄱阳湖水体悬浮颗粒物散射光谱分解方法研究

    陈莉琼; 陈晓玲; 田礼乔; 邱凤


    A model for partitioning the paniculate scattering coefficient into the contributions of suspended mineral particle and organic particle was proposed based on the measured data. The independent variables, I. E. The concentrations of mineral particles and organic particles in this study, were used to determine the mass-specific scattering cross section with the concurrent total suspended paniculate scattering coefficients collected during the field trip in Poyang Lake 2009. Results show that the scattering spectra of inorganic particles and organic particles can be successful derived by the proposed model, and the reconstructed total paniculate scattering coefficients are in better agreement with the measured values by the ordinary least square linear regressioa For the whole South Poyang Lake, mean absolute percentage errors between the measured scattering coefficients and reconstructed value were less than 25% over the main remote sensing effective wavebands such as 440, 532, 555 and 676 run. A remarkable lower predicted error, which can be controlled within 15%, were found at all stations with higher concentration of total suspended matters, while the spectral partitioning is less efficient at stations with total suspended particle concentration less than 15 mg ? L-1. Paniculate scattering spectrum retrieved by RMA shows that illite and montmorillonite are the major constituents of inorganic matters which dominate the light scattering properties of Poyang Lake. It is possible that scattering spectrum partitioned by the model could infer the major effective components in waters, and could be used to predict particulate scattering properties for highly turbid waters.%内陆水体复杂性为水体悬浮颗粒物散射光谱分解带来难题,也制约着水色遥感理论算法的发展.以2009年鄱阳湖秋季观测数据为基础,提出一种二元简化主轴(ranged major axis,RMA)方法的水体悬浮颗粒物散射光谱分解模型,对鄱阳湖水体中悬

  3. Determination of Sr and Ba partition coefficients between apatite and water from 5°C to 60°C: a potential new thermometer for aquatic paleoenvironments 1

    Balter, V.; Lécuyer, C.


    Apparent partition coefficients of Sr and Ba between calcium phosphate and water were measured experimentally for temperature ranging from 5°C to 60°C. Calcium phosphates were precipitated from an aqueous mixture of Na 2HPO 4 · 2H 2O (10 -2 M) and CaCl 2 · 2H 2O (10 -2 M). Spiked solutions of Sr or Ba were introduced into the CaCl 2 · 2H 2O solution at Sr/Ca and Ba/Ca ratios of 0.1. The experiment consisted in sampling the liquid and solid phases after 1, 6, 48, and 96 h of interaction. The amorphous calcium phosphate (ACP) precipitated early in the experiment was progressively replaced by hydroxylapatite (HAP), except at 5°C where brushite (di-calcium phosphate di-hydrate or DCPD) was formed. We observed that the crystallinity of the solid phase increased with time for a given temperature and increased with temperature for a given time of reaction. With the exception of the experiment at 5°C, yield (R%) and apparent partition coefficients (K a-wSr/Ca and K a-wBa/Ca) both decreased with increasing reaction time. After 96 h, R%, K a-wSr/Ca and K a-wBa/Ca were observed to be constant, suggesting that the solid phases were at steady-state with respect to the aqueous solutions. The thermodependence of Sr and Ba partitioning between apatite and water at low temperature could therefore be calculated: Log( Ka-wSr/Ca)=0.42±0.04(10 3T-1)-1.87±0.12( r2=0.94) Log( Ka-wBa/Ca)=1.96±0.06(10 3T-1)-7.19±0.20( r2=0.99) We also performed competition experiments between Sr and Ba. The thermodependence of the Sr/Ba partitioning between apatite and water was calculated after 96 h of reaction: Log( Ka-wSr/Ba)=-0.75±0.04(10 3T-1)+2.39±0.14( r2=0.97) This relationship reveals a discrimination of Ba in favor of Sr during their incorporation into HAP. Temperature trends deduced from the Ba/Ca of fish teeth recovered from the K/T boundary mimic those estimated from δ 18O(PO 4) measurements carried out on the same sample. Unless Sr, Ba and Ca contents of biogenic apatites are

  4. Experimental determination of salt partition coefficients between aqueous fluids, ice VI and ice VII: implication for the composition of the deep ocean and the geodynamics of large icy moons and water rich planets

    Journaux, Baptiste; Daniel, Isabelle; Cardon, Hervé; Petitgirard, Sylvain; Perrillat, Jean-Philippe; Caracas, Razvan; Mezouar, Mohamed


    The potential habitability of extraterrestrial large aqueous reservoir in icy moons and exoplanets requires an input of nutrients and chemicals that may come from the rocky part of planetary body. Because of the presence of high pressure (HP) water ices (VI, VII, etc.) between the liquid ocean and the silicates, such interactions are considered to be limited in large icy moons, like Ganymede and Titan, and water rich exoplanets. In the case of salty-rich oceans, recent experimental and modeling works have shown that aqueous fluids can be stable at higher pressures [1, 2]. This can ultimately allow direct interaction with the rocky core of icy moons. This effect is nevertheless limited and for larger bodies such as water rich exoplanets with much higher pressures in their hydrosphere, HP ice should be present between the rocky core and a putative ocean. Salts are highly incompatible with low pressure ice Ih, but recent experimental work has shown that alkali metal and halogen salts are moderately incompatible with ice VII, that can incorporate up to several mol/kg of salts [3, 4, 5]. As far as we know, no similar study has been done on ice VI, a HP ice phase expected inside large icy moons. We present here the first experimental data on the partition coefficient of RbI salt between aqueous fluids, ice VI and ice VII using in-situ synchrotron X-Ray single crystal diffraction and X-Ray fluorescence mapping (ESRF - ID-27 beam line [6]). Our experiment enable us to observe a density inversion between ice VI and the salty fluid, and to measure the values of salt partition coefficients between the aqueous fluid and ice VI (strongly incompatible) and ice VII (moderately incompatible). Using the volumes determined with X-Ray diffraction, we were able to measure the density of salty ice VI and ice VII and determine that salty ice VI is lighter than pure H2O ice VI. These results are very relevant for the study of water rich planetary bodies interior because the partition

  5. Apparent Oil-water Partition Coefficient and Aqueous Chemical Stability of Venlafaxine Hydrochloride%盐酸文拉法辛表观油水分配系数及其溶液化学稳定性的研究

    张嫒; 谷福根


    目的:测定盐酸文拉法辛(Ven)的表观油水分配系数(P)及其水溶液的化学稳定性,为今后研制Ven的黏膜吸收给药液体制剂奠定基础.方法:采用HPLC法测定Ven的浓度;测定Ven在正辛醇-水/pH 2~10磷酸缓冲液系统中的P值;测定Ven在pH 2~12磷酸缓冲液以及不同离子强度条件下的降解百分率.结果:Ven在正辛醇-水系统中的P值为0.16;在正辛醇-pH 2~10缓冲液系统中,当pH≤6.0时,Ven的P值接近于1,当pH>6.0时,随着pH的增加,药物的P值显著增大.Ven溶液在pH≤8.0时,其化学稳定性良好,在碱性pH下,化学稳定性较差;离子强度对Ven溶液的化学稳定性无影响.结论:Ven的油水分配系数及溶液的化学稳定性与pH密切相关.在pH约为7.0时,Ven具有较高油水分配系数及化学稳定性.%Objective:To investigate the apparent oil-water partition coefficient ( P) and aqueous chemical stability of venlafaxine hydrochloride ( Ven) and provide theoretical basis for the development of Ven transmucous absorption liquid preparation. Methods:The concentration of Ven was determined by HPLC. The P value was studied in n-octanol-water/phosphate buffers system with the pH range of 2-10. The degradation percentage of Ven was also determined in the phosphate buffer solutions with the pH range of 2-12 and different ionic strength. Results:The P value of Ven in the n-octanol-water system was 0. 16. When pH≤ 6. 0, the P value of the drug in n-octanol-phosphate buffer system was close to 1, and when the pH>6. 0,the P value significantly increased with the rise of pH. Ven aqueous solution showed good chemical stability when pH≤8. 0, however, the chemical stability of the drug aqueous solution became poor with alkaline pH value. Ionic strength showed no obvious effect on the chemical stability of Ven aqueous solution. Con-clusion: The apparent oil-water partition coefficient and aqueous chemical stability of Ven are closely related to pH values. The drug

  6. Predicting soil sorption coefficients of organic chemicals using a neural network model

    Gao, C.; Govind, R. [Univ. of Cincinnati, OH (United States). Dept. of Chemical Engineering; Tabak, H.H. [Environmental Protection Agency, Cincinnati, OH (United States)


    The soil/sediment adsorption partition coefficient normalized to organic carbon (K{sub oc}) is extensively used to assess the fate of organic chemicals in hazardous waste sites. Several attempts have been made to estimate the value of K{sub oc} from chemical structure or its parameters. The primary purpose of this study was to develop a nonlinear model for estimating K{sub oc} applicable to polar and nonpolar organics based on artificial neural networks using the octanol/water partition coefficient (K{sub ow}) and water solubility (S). An analytic equation was obtained by starting with a neural network, converging the bias and weight values using the available data on water solubility, octanol/water partition coefficient, and the normalized soil/sediment adsorption partition coefficient, and then combining the equations for each node in the final neural network. For the 119 chemicals in the training set, estimates using the neural network equation lie outside the 2{sigma} region (the standard deviation for the training set, {sigma} = 0.52) for only five chemicals, while all the chemicals in the test set lie within the 2{sigma} region. It was concluded that the neural network equation outperforms the linear models in fitting the K{sub oc} values for the training set and predicting them for the test set.

  7. Polymers as reference partitioning phase: polymer calibration for an analytically operational approach to quantify multimedia phase partitioning

    Gilbert, Dorothea; Witt, Gesine; Smedes, Foppe


    as the basis for a deeper insight into partitioning differences of HOCs between polymers, calibrating analytical methods, and consistency checking of existing and calculation of new partition coefficients. Polymer-polymer partition coefficients were determined for polychlorinated biphenyls (PCBs), polycyclic...... larger deviations from unity were indicated within the group of silicones and between silicones and LDPE. Uncertainty in polymer volume due to imprecise coating thickness or the presence of fillers was identified as the source of error for partition coefficients. New polymer-based (LDPE-lipid, PDMS......-air) and multimedia partition coefficients (lipid-water, air-water) were calculated by applying the new concept of a polymer as reference partitioning phase and by using polymer-polymer partition coefficients as conversion factors. The present study encourages the use of polymer-polymer partition coefficients...

  8. Complexos de inclusão de indometacina com hidroxipropil-beta-ciclodextrina: estudos de dissolução e coeficiente de partição Inclusion compounds of indomethacin with hydroxypropyl-beta-cyclodextrin: dissolution profile and partition coefficient evaluation

    Ana Cristina Ribeiro Rama


    Full Text Available A indometacina, antiinflamatório não-esteróide, é praticamente insolúvel em água. A hidroxipropil-beta-ciclodextrina confere aos fármacos nela incluídos melhores características de solubilidade. A formação de complexos com indometacina protege da hidrólise, aumentando a solubilidade. O objetivo desse trabalho foi estudar a influência da complexação por liofilização e por spray-dried, na dissolução e coeficiente de partição. Os resultados dos estudos de dissolução dos complexos de inclusão obtidos por liofilização quando comparados com os obtidos por spray-dryer, apresentam quer maior velocidade de dissolução quer melhor eficiência de dissolução. Os resultados da análise do coeficiente de partição, com ambos os métodos de complexação, confirmam a teoria de que são várias as forças intervenientes neste processo e não é só a fração livre de fármaco que condiciona o transporte para a fase orgânica, reforçando a importância do pH do meio. No estudo com o tampão fosfato pH 7,0, as variações no grau de transporte pela adição de ciclodextrina são muito pequenas, não ocorrendo alteração significativa dos valores de Log P*, verificando-se alterações mais significativas quando se utiliza o tampão fosfato pH 5,5. A complexação aumentou a capacidade de solubilização e dissolução da indometacina, a qual tem caráter lipófilo, sem alterar as características que lhe permitem ter boa capacidade de difusão através de membranas biológicas.Indomethacin, a non steroidal anti-inflamatory, is practically water insoluble. Hydroxypropyl-beta-cyclodextrin grants better solubility characteristics to included drugs. Indomethacin's complexation protects from hydrolysis, enhancing solubility and dissolution. The aim is to study the influence of complexation methods, freeze and spray-dryer, on indomethacin dissolution and partition coefficient. Dissolution results show that freeze-dried inclusion complex

  9. Metal partitioning and toxicity in sewage sludge

    Carlson-Ekvall, C.E.A.; Morrison, G.M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Sanitary Engineering


    Over 20 years of research has failed to provide an unequivocal correlation between chemically extracted metals in sewage sludge applied to agricultural soil and either metal toxicity to soil organisms or crop uptake. Partitioning of metals between phases and species can provide a better estimation of mobility and potential bioavailability. Partition coefficients, K{sub D} for Cd, Cu, Pb and Zn in a sludge/water solution were determined considering the sludge/water solution as a three-phase system (particulate, colloidal and electrochemically available) over a range of pH values, ionic strengths, contact times and sludge/water ratios and compared with the KD values for sludge/water solution as a two-phase system (aqueous phase and particulate phase). Partitioning results were interpreted in terms of metal mobility from sludge to colloids and in terms of potential bioavailability from colloids to electrochemically available. The results show that both mobility and potential bioavailability are high for Zn, while Cu partitions into the mobile colloidal phase which is relatively non-bioavailable. Lead is almost completely bound to the solid phase, and is neither mobile nor bioavailable. A comparison between K, values and toxicity shows that Zn in sludge is more toxic than can be accounted for in the aqueous phase, which can be due to synergistic effects between sludge organics and Zn. Copper demonstrates clear synergism which can be attributed to the formation of lipid-soluble Cu complexes with known sludge components such as LAS, caffeine, myristic acid and nonylphenol.

  10. Correlation of tissue-plasma partition coefficients between normal tissues and subcutaneous xenografts of human tumor cell lines in mouse as a prediction tool of drug penetration in tumors.

    Poulin, Patrick; Hop, Cornelis Eca; Salphati, Laurent; Liederer, Bianca M


    Understanding drug distribution and accumulation in tumors would be informative in the assessment of efficacy in targeted therapy; however, existing methods for predicting tissue drug distribution focus on normal tissues and do not incorporate tumors. The main objective of this study was to describe the relationships between tissue-plasma concentration ratios (Kp ) of normal tissues and those of subcutaneous xenograft tumors under nonsteady-state conditions, and establish regression equations that could potentially be used for the prediction of drug levels in several human tumor xenografts in mouse, based solely on a Kp value determined in a normal tissue (e.g., muscle). A dataset of 17 compounds was collected from the literature and from Genentech. Tissue and plasma concentration data in mouse were obtained following oral gavage or intraperitoneal administration. Linear regression analyses were performed between Kp values in several normal tissues (muscle, lung, liver, or brain) and those in human tumor xenografts (CL6, EBC-1, HT-29, PC3, U-87, MCF-7-neo-Her2, or BT474M1.1). The tissue-plasma ratios in normal tissues reasonably correlated with the tumor-plasma ratios in CL6, EBC-1, HT-29, U-87, BT474M1.1, and MCF-7-neo-Her2 xenografts (r(2) in the range 0.62-1) but not with the PC3 xenograft. In general, muscle and lung exhibited the strongest correlation with tumor xenografts, followed by liver. Regression coefficients from brain were low, except between brain and the glioblastoma U-87 xenograft (r(2) in the range 0.62-0.94). Furthermore, reasonably strong correlations were observed between muscle and lung and between muscle and liver (r(2) in the range 0.67-0.96). The slopes of the regressions differed depending on the class of drug (strong vs. weak base) and type of tissue (brain vs. other tissues and tumors). Overall, this study will contribute to our understanding of tissue-plasma partition coefficients for tumors and facilitate the use of physiologically

  11. The interaction of fiber, supplied by distillers dried grains with solubles, with an antimicrobial and a nutrient partitioning agent on nitrogen balance, water utilization, and energy digestibility in finishing pigs.

    Pilcher, C M; Arentson, R; Patience, J F


    The objective of this study was to determine if a higher-fiber diet alters the response of finishing pigs to an antimicrobial (tylosin phosphate [TP]) and a nutrient partitioning agent (ractopamine HCl [RAC]) in terms of N and water utilization and energy digestibility. Seventy-two gilts (initial BW = 107.4 ± 4.2 kg) were blocked by weight and allotted to 1 of 8 dietary treatments. Treatments were arranged as a 2 × 2 × 2 factorial: distillers dried grains with solubles (DDGS; 0 vs. 30%), RAC (0 mg of RAC/kg and 0.70% standardized ileal digestible [SID] Lys vs. 5 mg of RAC/kg and 0.95% SID Lys) and TP (0 vs. 44 mg of TP/kg). Pig was the experimental unit, with 9 replications per treatment. Pigs were housed in individual metabolism crates and fed treatment diets for 17 d. Feed was provided twice daily, as much as the pigs could consume within 1 h per meal, and water was provided to the pigs between feeding periods, ad libitum. Fecal and urine collection occurred on d 7 and 8 and on d 15 and 16, for sampling periods 1 and 2, respectively. Pigs fed the DDGS diets had reduced ADG ( interaction ( 0.10). Pigs fed DDGS diets had higher N intake ( < 0.01) and higher fecal ( < 0.0001) and urinary ( < 0.01) N excretion with no difference in N retention (g/d). Overall, RAC increased N retention by 33% ( < 0.0001) and the response to RAC was similar in both corn-soybean meal-based and corn-soybean meal-DDGS-based diets. Tylosin phosphate tended to improve growth performance in pigs fed corn-soybean meal-based diets but not in diets containing 30% DDGS; however, this response was not explained by changes in N balance or in energy digestibility.

  12. The Fibonacci partition triangles

    Fahr, Philipp


    In two previous papers we have presented partition formulae for the Fibonacci numbers motivated by the appearance of the Fibonacci numbers in the representation theory of the 3-Kronecker quiver and its universal cover, the 3-regular tree. Here we show that the basic information can be rearranged in two triangles. They are quite similar to the Pascal triangle of the binomial coefficients, but in contrast to the additivity rule for the Pascal triangle, we now deal with additivity along hooks, or, equivalently, with additive functions for valued translation quivers. As for the Pascal triangle, we see that the numbers in these Fibonacci partition triangles are given by evaluating polynomials. We show that the two triangles can be obtained from each other by looking at differences of numbers, it is sufficient to take differences along arrows and knight's moves.

  13. Polymers as Reference Partitioning Phase: Polymer Calibration for an Analytically Operational Approach To Quantify Multimedia Phase Partitioning.

    Gilbert, Dorothea; Witt, Gesine; Smedes, Foppe; Mayer, Philipp


    Polymers are increasingly applied for the enrichment of hydrophobic organic chemicals (HOCs) from various types of samples and media in many analytical partitioning-based measuring techniques. We propose using polymers as a reference partitioning phase and introduce polymer-polymer partitioning as the basis for a deeper insight into partitioning differences of HOCs between polymers, calibrating analytical methods, and consistency checking of existing and calculation of new partition coefficients. Polymer-polymer partition coefficients were determined for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) by equilibrating 13 silicones, including polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) in methanol-water solutions. Methanol as cosolvent ensured that all polymers reached equilibrium while its effect on the polymers' properties did not significantly affect silicone-silicone partition coefficients. However, we noticed minor cosolvent effects on determined polymer-polymer partition coefficients. Polymer-polymer partition coefficients near unity confirmed identical absorption capacities of several PDMS materials, whereas larger deviations from unity were indicated within the group of silicones and between silicones and LDPE. Uncertainty in polymer volume due to imprecise coating thickness or the presence of fillers was identified as the source of error for partition coefficients. New polymer-based (LDPE-lipid, PDMS-air) and multimedia partition coefficients (lipid-water, air-water) were calculated by applying the new concept of a polymer as reference partitioning phase and by using polymer-polymer partition coefficients as conversion factors. The present study encourages the use of polymer-polymer partition coefficients, recognizing that polymers can serve as a linking third phase for a quantitative understanding of equilibrium partitioning of HOCs between any two phases.

  14. Comparison of amino acid digestibility coefficients for corn, corn gluten meal, and corn distillers dried grains with solubles among 3 different bioassays.

    Kim, E J; Utterback, P L; Parsons, C M


    The objective of this study was to determine standardized AA digestibility of corn, corn gluten meal, and 3 distillers dried grains with solubles (DDGS) using the precision-fed cecectomized rooster assay (PFR), the standardized ileal AA broiler chicken assay (SIAAD), and a newly developed precision-fed ileal broiler chicken assay (PFC). For the PFR, cecectomized roosters were precision-fed approximately 30 g of feed sample, and excreta were collected 48 h postfeeding. For the SIAAD, 16-d-old broilers were ad libitum fed a semi-purified diet containing the feed samples as the sole source of protein from 17 to 21 d, with ileal digesta collected at 21 d. For the PFC, 22-d-old broiler chickens were precision-fed 10 g of feed and ileal digesta were collected at 4 h postfeeding. For corn, the PFC yielded significantly higher digestibilities than the SIAAD and PFR for several AA. For corn gluten meal, the PFR yielded significantly higher values than the PFC for the majority of the AA, with the SIAAD yielding intermediate values. When 3 DDGS samples were evaluated, the PFR produced higher digestibilities than the PFC for all 3 DDGS samples for most of the AA. When comparing the PFR and the SIAAD, the PFR yielded higher values than the SIAAD for one DDGS, whereas there was generally no significant difference between these 2 methods for the other 2 DDGS samples. The results of this study indicate there were differences among standardized AA digestibility values for the PFR, SIAAD, and PFC in some instances. The differences among methods were not consistent; however, the PFR yielded higher digestibility values than the PFC for 4 of the 5 ingredient samples.

  15. Measurements and Application of Partition Coefficients of Compounds Suitable for Tracing Gas Injected Into Oil Reservoirs Mesures et applications des coefficients de partage de composants utilisables comme gaz traceurs injectés dans des réservoirs de pétrole

    Dugstad O.


    Full Text Available Tracing of injection gas in oil reservoirs is a technique used to improve the description of permeability distributions in situ. Results from dynamic laboratory experiments of gas tracers are reported. Gas tracers are delayed when flooding through a reservoir by the partitioning into the oil phase. A knowledge of this effect is important to optimize the interpretation of field tracer tests. The partition is quantified by the partition coefficient K. Two chemical tracers perfluoromethylcyclopentane (PMCP and perfluoromethylcyclohexane (PMCH and the radioactive 14C labelled ethane have been studied here. The two chemical compounds are new as reservoir tracers and no field results with these tracers are reported in the open literature. Our group has, however, recently applied these compound successfully as tracers in a North Sea reservoir. Les traceurs représentent un outil précieux pour améliorer la description des gisements. On les a utilisés pour obtenir des renseignements sur la configuration de l'écoulement des fluides injectés et sur leur vitesse, sur l'instant de percé des venues d'eau et sur leur origine précise, sur les traitements d'amélioration du balayage, sur les hétérogénéités importantes telles que fractures, barrières d'écoulement et stratifications de la perméabilité. Dans les gisements importants comportant plusieurs puits de production et plusieurs puits d'injection, il est donc souhaitable de disposer de plusieurs traceurs afin de pouvoir injecter différents traceurs ou mélanges de traceurs dans les différents puits. L'article présenté ici est une contribution a l'effort fait pour étendre le nombre de gaz traceurs fiables applicables aux gisements. L'article présente les résultats d'essais dynamiques en laboratoires dans lesquels on injecte des traceurs à travers un milieu poreux. Lorsqu'ils traversent un réservoir, les gaz traceurs sont retardés du fait de leur ségrégation dans la phase huile. La

  16. Solubility properties of siloxane polymers for chemical sensors

    Grate, J.W. [Pacific Northwest Lab., Richland, WA (United States); Abraham, M.H. [University College, London (United Kingdom)


    This paper discusses the factors governing the sorption of vapors by organic polymers. The principles have been applied in the past for designing and selecting polymers for acoustic wave sensors; however they apply equally well to sorption of vapors by polymers used on optical chemical sensors. A set of solvation parameters (a table is presented for various organic vapors) have been developed that describe the particular solubility properties of individual solute molecules; they are used in linear solvation energy relationships (LSER) that model the sorption process. LSER coefficients are tabulated for five polysiloxanes; so are individual interaction terms for each of the 5 polymers. Dispersion interactions play a major role in determining overall partition coefficients; the log L{sup 16} (gas-liquid partition coefficient of solute on hexadecane) value of vapors are important in determining overall sorption. For the detection of basic vapors such as organophosphates, a hydrogen-bond acidic polymers will be most effective at sorbing them. Currently, fiber optic sensors are being developed where the cladding serves as a sorbent layer to collect and concentrate analyte vapors, which will be detected and identified spectroscopically. These solubility models will be used to design the polymers for the cladding for particular vapors.

  17. Software Partitioning Technologies


    1 Software Partitioning Technologies Tim Skutt Smiths Aerospace 3290 Patterson Ave. SE Grand Rapids, MI 49512-1991 (616) 241-8645 skutt_timothy...Limitation of Abstract UU Number of Pages 12 2 Agenda n Software Partitioning Overview n Smiths Software Partitioning Technology n Software Partitioning...Partition Level OS Core Module Level OS Timers MMU I/O API Layer Partitioning Services 6 Smiths Software Partitioning Technology n Smiths has developed

  18. Phase partitioning of trace metals in a contaminated estuary influenced by industrial effluent discharge.

    Wang, Wenhao; Wang, Wen-Xiong


    Severe trace metal pollution due to industrial effluents releases was found in Jiulong River Estuary, Southern China. In this study, water samples were collected during effluent release events to study the dynamic changes of environmental conditions and metal partitioning among dissolved, particulate and colloidal phases controlled by estuarine mixing. Intermittent effluent discharges during low tide caused decreasing pH and dissolved oxygen, and induced numerous suspended particulate materials and dissolved organic carbon to the estuary. Different behaviors of Cu, Zn, Ni, Cr and Pb in the dissolved fraction against the conservative index salinity indicated different sources, e.g., dissolved Ni from the intermittent effluent. Although total metal concentrations increased markedly following effluent discharges, Cu, Zn, Cr, Pb were predominated by the particulate fraction. Enhanced adsorption onto particulates in the mixing process resulted in elevated partitioning coefficient (Kd) values for Cu and Zn, and the particle concentration effect was not obvious under such anthropogenic impacts. Colloidal proportion of these metals (especially Cu and Zn) showed positive correlations with dissolved or colloidal organic carbon, suggesting the metal-organic complexation. However, the calculated colloidal partitioning coefficients were relatively constant, indicating the excess binding capacity. Overall, the intermittent effluent discharge altered the particulate/dissolved and colloidal/soluble phase partitioning process and may further influence the bioavailability and potential toxicity to aquatic organisms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Effect of Sulfur on Siderophile Element Partitioning Between Olivine and Martian Primary Melt

    Usui, T.; Shearer, C. K.; Righter, K.; Jones, J. H.


    Since olivine is a common early crystallizing phase in basaltic magmas that have produced planetary and asteroidal crusts, a number of experimental studies have investigated elemental partitioning between olivine and silicate melt [e.g., 1, 2, 3]. In particular, olivine/melt partition coefficients of Ni and Co (DNi and DCo) have been intensively studied because these elements are preferentially partitioned into olivine and thus provide a uniquely useful insight into the basalt petrogenesis [e.g., 4, 5]. However, none of these experimental studies are consistent with incompatible signatures of Co [e.g., 6, 7, 8] and Ni [7] in olivines from Martian meteorites. Chemical analyses of undegassed MORB samples suggest that S dissolved in silicate melts can reduce DNi up to 50 % compared to S-free experimental systems [9]. High S solubility (up to 4000 ppm) for primitive shergottite melts [10] implies that S might have significantly influenced the Ni and Co partitioning into shergottite olivines. This study conducts melting experiments on Martian magmatic conditions to investigate the effect of S on the partitioning of siderophile elements between olivine and Martian primary melt.

  20. Enzymatic hydrolysis of cellulose in aqueous two-phase systems. 1. Partition of cellulases from Trichoderma reesei

    Tjerneld, F.; Persson, J.; Albertsson, P.A.; Hahn-Haegerdal, B.


    The partitioning of endo-..beta..-glucanase, exo-..beta..-glucananse, and ..beta..-glucosidase from Trichoderma reesei QM 9414 in aqueous two-phase systems has been studied with the object of designing a phase system for continuous bioconversion of cellulose. The partitioning of the enzymes in two-phase systems composed of various water soluble polymeric compounds were studied. Systems based on dextran and polyethylene glycol (PEG) were optimal for one sidedly partitioning of the enzymes to the bottom phase. The influence of polymer molecular weights, polymer concentration, ionic composition of the medium, pH, temperature, and adsorption of the enzymes to cellulose on the enyzme partition coefficients (K) were studied. By combining the effects of polymer molecular weight and adsorption to cellulose, K values could be reduced for endo-..beta..-glucanase to 0.02 and for ..beta..-glucosidase to 0.005 at 20 degrees C in a phase system of Dvalues could be reduced for endo-..beta..-glucanase to 0.02 and for ..beta..-glucosidase to 0.005 at 20 degrees C in a phase system of Dextran 40-PEG 40000 in the presence of excess cellulose. At 50 degrees C, K values were increased by a factor of two. In a phase system based on inexpensive crude dextran and PEG, the partition coefficient for endo-..beta..-glucanase was 0.16 and for beta-glucosidase was 0.14 at 20 degrees C with excess cellulose present.

  1. Partitioning and lipophilicity in quantitative structure-activity relationships.

    Dearden, J. C.


    The history of the relationship of biological activity to partition coefficient and related properties is briefly reviewed. The dominance of partition coefficient in quantitation of structure-activity relationships is emphasized, although the importance of other factors is also demonstrated. Various mathematical models of in vivo transport and binding are discussed; most of these involve partitioning as the primary mechanism of transport. The models describe observed quantitative structure-ac...

  2. Thermodynamics of phenanthrene partition into solid organic matter from water

    CHEN Bao-liang; ZHU Li-zhong; TAO Shu


    The thermodynamic behavior of organic contaminants in soils is essential to develop remediation technologies and assess risk from alternative technologies. Thermodynamics of phenanthrene partition into four solids (three soils and a bentonite) from water were investigated. The thermodynamics parameters (Δ H, Δ G°, Δ S°, ) were calculated according to experimental data. The total sorption heats of phenanthrene to solids from water ranged from - 7.93 to - 17.1 kJ/mol, which were less exothermic than the condensation heat of phenanthrene-solid(i.e., - 18.6 k J/mol). The partition heats of phenanthrene dissolved into solid organic matter ranged from 23.1 to 32.2k J/mol, which were less endothermic than the aqueous dissolved heat of phenanthrene(i. e., 40.2 kJ/mol), and were more endothermic than the fusion heat of phenanthrene-solid (i. e., 18.6 kJ/mol). The standard free energy changes, Δ G°, are all negative which suggested that phenanthrene sorption into solid was a spontaneous process. The positive values of standard entropy changes,ΔS° , show a gain in entropy for the transfer of phenanthrene at the stated standard state. Due to solubility-enhancement of phenanthrene,the partition coefficients normalized by organic carbon contents decrease with increasing system temperature(i. e., In Koc = -0.284In S +9.82( n =4, r2 = 0.992)). The solubility of phenanthrene in solid organic matter increased with increasing temperatures. Transports of phenanthrene in different latitude locations and seasons would be predicted according to its sorption thermodynamics behavior.

  3. Unique Path Partitions

    Bessenrodt, Christine; Olsson, Jørn Børling; Sellers, James A.


    We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions.......We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions....

  4. Partition Equilibrium Between Charged Membrane and Single Electrolyte Aqueous Solution

    徐铜文; 杨伟华; 何柄林


    Ionic partition equilibrium in charged membrane immersed in solution of single electrolyte with monovalence or multi-valence is systematically investigated and several expressions are established for determination of partition coefficients. On this basis, the effects of the ratio of membrane charge density to hulk electrolyte solution concentration, the charge sign and valence of electrolyte ions and the type of membrane on the partition equilibrium were analyzed and simulated with in chosen parameters. It is revealed that ion partition is not related solely withthe respective concentrations but also definitely with the concentration ratio of fixed group to bulk solution in addition to the charge sign and the valence. For a counterion, the partition coefficient increases with this ratio and the valence; while for a coion, the partition coefficient decreases with this ratio and the valence. The theoreticalcal culations were compared with the experimental data and a good agreement was observed.

  5. Partition Equilibrium Between Charged Membrane and Single Electrolyte Aqueous Solution


    Ionic partition equilibrium in charged membrane immersed in solution of single electrolyte with mono valence or multi-valence is systematically investigated and several expressions are established for determination of partition coefficients. On this basis, the effects of the ratio of membrane charge density to bulk electrolyte solution concentration, the charge sign and valence of electrolyte ions and the type of membrane on the partition equilibrium were analyzed and simulated within chosen parameters. It is revealed that ion partition is not related solely with the respective concentrations but also definitely with the concentration ratio of fixed group to bulk solution in addition to the charge sign and the valence. For a counterion, the partition coefficient increases with this ratio and the valence; while for a coion, the partition coefficient decreases with this ratio and the valence. The theoretical calculations were compared with the experimental data and a good agreement was observed.

  6. 热力学数学模型对塑料中化学物向食品模拟液中迁移平衡时分配系数的预测研究%Study of predicting equilibrium partition coefficient of migrants in food simulants from plastic by thermodynamic mathematical modeling

    肖少军; 张钦发; 向红; 范小平; 岳淑丽


    目的:分配系数能够直接反映出塑料包装材料中有害化学物向食品迁移的水平,研究分配系数与塑料包装材料、迁移物及食品(模拟物)三者之间的关系有重要意义。方法以 Scatchard-Hildebrand 统计热力学理论为基础,从热力学平衡角度分析了化学物在包装材料/食品体系中的迁移和分配过程,建立了一个预测化学物迁移平衡时分配系数的热力学数学模型。通过所建立的初级数学模型对聚乙烯薄膜中四种抗氧化剂,即2,6-二叔丁基-4-甲基苯酚(BHT)、二丁基羟基茴香醚(BHA)、Irganox1010和 Irganox1076向脂肪类食品模拟物异辛烷迁移平衡时状态进行模拟计算,并与已公开发表的实验数据进行了对比。结果聚乙烯薄膜中四种抗氧剂向异辛烷中迁移平衡的分配系数模拟值与实验值随温度变化趋势一致。结论该热力学模型符合迁移理论,对PE/抗氧剂/脂肪类食品体系分配系数的预测有一定的适用性。%Objective Partition coefficient can directly reflect the migration level of the compounds from plastic package materials to food, it is important to study the relationship between the partition coefficient and plastic materials, the migrates and the food(simulant). Methods Being based on the Scatchard-Hildebrand sta-tistical thermodynamic theory, the processes of the compounds migrate and distribute in packaging material/food system were analyzed, and a thermodynamic mathematical model which can predict the equilibrium partition coefficient of migrants was established. The state of migration balance of four antioxidants (2,6-di-tert-butyl-4-methyl phenol, dibutyl hydroxyl anisole, Irganox 1010 and Irganox 1076) from PE to isooctane was simulated through the mathematical model, and the values were compared with the published experimental data. Results The trends with temperature of the simulate partition coefficients of four antioxidants in PE migrate to isooctane

  7. Low aqueous solubility of 11-cis-retinal limits the rate of pigment formation and dark adaptation in salamander rods.

    Frederiksen, Rikard; Boyer, Nicholas P; Nickle, Benjamin; Chakrabarti, Kalyan S; Koutalos, Yiannis; Crouch, Rosalie K; Oprian, Daniel; Cornwall, M Carter


    We report experiments designed to test the hypothesis that the aqueous solubility of 11-cis-retinoids plays a significant role in the rate of visual pigment regeneration. Therefore, we have compared the aqueous solubility and the partition coefficients in photoreceptor membranes of native 11-cis-retinal and an analogue retinoid, 11-cis 4-OH retinal, which has a significantly higher solubility in aqueous medium. We have then correlated these parameters with the rates of pigment regeneration and sensitivity recovery that are observed when bleached intact salamander rod photoreceptors are treated with physiological solutions containing these retinoids. We report the following results: (a) 11-cis 4-OH retinal is more soluble in aqueous buffer than 11-cis-retinal. (b) Both 11-cis-retinal and 11-cis 4-OH retinal have extremely high partition coefficients in photoreceptor membranes, though the partition coefficient of 11-cis-retinal is roughly 50-fold greater than that of 11-cis 4-OH retinal. (c) Intact bleached isolated rods treated with solutions containing equimolar amounts of 11-cis-retinal or 11-cis 4-OH retinal form functional visual pigments that promote full recovery of dark current, sensitivity, and response kinetics. However, rods treated with 11-cis 4-OH retinal regenerated on average fivefold faster than rods treated with 11-cis-retinal. (d) Pigment regeneration from recombinant and wild-type opsin in solution is slower when treated with 11-cis 4-OH retinal than with 11-cis-retinal. Based on these observations, we propose a model in which aqueous solubility of cis-retinoids within the photoreceptor cytosol can place a limit on the rate of visual pigment regeneration in vertebrate photoreceptors. We conclude that the cytosolic gap between the plasma membrane and the disk membranes presents a bottleneck for retinoid flux that results in slowed pigment regeneration and dark adaptation in rod photoreceptors.

  8. 替莫唑胺的平衡溶解度与油水分配系数的测定%Determination of equilibrium solubility and oil-water partition coefficient on temozolomide

    李梅; 刘俊丽; 王忠兰; 黄桂华


    目的 测定替莫唑胺的平衡溶解度和油水分配系数,为制剂的研究提供可靠依据.方法 采用摇瓶法测定替莫唑胺在水、不同 pH PBS中的平衡溶解度及油水分配系数.结果 替莫唑胺在水及pH 1.75、4.32、4.97、5.57、6.06的PBS中的平衡溶解度分别是5.26、6.83、6.67、4.59、3.47、3.53 mg·mL-1,在正辛醇-PBS中的油水分配系数分别为0.21、0.58、1.28、2.61、14.74.结论 该测定方法简单可行,37 ℃替莫唑胺微溶于水,平衡溶解度随pH的增加而降低,油水分配系数随pH的增加而增加.

  9. DFT and Position of Cl Substitution (PCS) Methods Studies on n-Octanol/water Partition Coefficients (lgKow) and Aqueous Solubility (-lgSw) of All PCDD Congeners


    Optimized calculations of 75 PCDDs and their parent DD were carded out at the B3LYP/6-31G* level by density functional theory (DFT) method. The structural parameters were obtained and significant correlation between the Cl substitution position and some structural parameters was found. Consequently, the number of Cl substitution positions was taken as theoretical descriptors to establish two novel QSPR models for predicting lgKow and -lgSw of all PCDD congeners. The two models achieved in this work contain two variables (Nα and Nβ), of which r = 0.9312, 0.9965 and SD = 0.27, 0.12 respectively, and t values are all large. The variation inflation factors (VIF) of variables in the two models herein are both less than 5.0, suggesting high accuracy of the lgKow and -lgSw predicting models, and the results of cross-validation test also show that the two models exhibit optimum stability and good predictive power. By comparison, the correlation and predictive ability of the present work are more advantageous than those obtained using semi-empirical AM1 and GC-RI methods.

  10. Deep eutectic solvents in countercurrent and centrifugal partition chromatography.

    Roehrer, Simon; Bezold, Franziska; García, Eva Marra; Minceva, Mirjana


    Deep eutectic solvents (DESs) were evaluated as solvents in centrifugal partition chromatography, a liquid-liquid chromatography separation technology. To this end, the partition coefficients of ten natural compounds of different hydrophobicity were determined in non-aqueous biphasic systems containing DES. The influence of the composition of DESs and the presence of water in the biphasic system on the partition coefficient were also examined. In addition, several process relevant physical properties of the biphasic system, such as the density and viscosity of the phases, were measured. A mixture of three to four hydrophobic compounds was successfully separated in a centrifugal partition extractor using a heptane/ethanol/DES biphasic system.

  11. The sulfur partition ratio and the sulfide capacity of Na2O-SiO2 slags at 1200 °C

    Chan, Allen H.; Fruehan, R. J.


    The sulfur partition ratio between carbon-saturated iron and Na2O-SiO2 slags and the sulfide capacity of these slags have been measured at 1200 °C. The two measurements are consistent with each other and the results are compared with other investigations. These slags have higher sulfide capacities and partition ratios than equivalent CaO-based slags and are thus attractive desulfurizers. Both the sulfide capacity and the partition ratio increase with increasing Na2O. The activity coefficient of Na2S has been calculated; it also increases with increasing Na2O. The solubility of sulfur in a slag of 0.4 mole fraction Na2O is estimated to be 5 pct.

  12. Fluorine partitioning between hydrous minerals and aqueous fluid at 1 GPa and 770-947 °C: A new constraint on slab flux

    Wu, Jia; Koga, Kenneth T.


    Mechanisms of volatile element transfer from subducting slab to the melting region beneath arc volcanoes are probably the least understood process in arc magma genesis. Fluorine, which suffers minimal degassing in arc primitive melt inclusions, is highly enriched in arc lavas and retains information about the role of volatiles during magma genesis at depth. Experimentally determined solubility of F in aqueous fluids, and partition coefficients of F between fluid and minerals provide first order geochemical constraints about the character of the volatile-transporting agent. We present experimentally determined F solubility in fluid in equilibrium with hornblende and a humite group mineral at 1 GPa, from 770 to 947 °C, and partition coefficients between these phases. The composition of the fluid is determined by mass-balance calculations and consistency is verified by high pressure liquid chromatography measurements of the quenched fluids. The partition coefficient DFFlu /Hb can be represented by a single value of 0.13 ± 0.03. The average F concentration in the fluid is 2700 ppm for F-rich experiments, constraining the maximum amount of F carried by fluid in the presence of amphibole. Where the initial natural F concentrations in the slab are much lower than in our experiments, the increase of F concentration in the sub-arc mantle by a fluid in equilibrium with hornblende is expected to be no more than a few ppm. Thus significant arc lava F enrichments cannot result from aqueous fluids deriving from an amphibole-bearing subducting slab.

  13. The effect of sulfide dissolved in silicate melts on enhancing the solubility of the Highly Siderophile Elements

    O'Neill, H. S.


    There are large inconsistencies among experimental studies of Highly Siderophile Element (HSE) partitioning relations between silicates and metal or sulfide phases, which has usually been attributed to "micronuggets", a general term for sub-optical (approximately HSE sulfide-melt/silicate-melt partition coefficients, where results range over several orders of magnitude. Moreover, nearly all the reported results of directly determined sulfide-melt/silicate-melt partition coefficients are considerably lower than values calculated by combining metal/silicate-melt with metal/sulfide-melt partition coefficients. This discrepancy has been attributed to large effects of S dissolved as sulfide in the silicate melts on HSE solubilities. As such large effects are not expected from the thermodynamic modeling of sulfide solubilities in silicate melts, it has been proposed that HSEs dissolve in sulfide-containing silicate melts by forming HSE-S complexes. This idea has been tested by experiments that compare the solubilities of Ir, Re and Ru in a high-TiO2 silicate melt both with and without dissolved sulfide at 1400 to 1600ºC at atmospheric pressure. The high TiO2 suppresses micronuggets. Experiments were analysed by LA-ICP-MS, with detection limits approaching 2 ppb. For Ir, the results show that at fO2 low enough to enable measurable sulfide in the melt, the presence of the sulfide just raises the level of dissolved Ir above detection limits. These results suggest a fairly large influence of the sulfide, but are not quantitative. By contrast, the experiments on Ru and Re clearly show only a modest effect of dissolved sulfide.

  14. Vasoconstriction Potency Induced by Aminoamide Local Anesthetics Correlates with Lipid Solubility

    Hui-Jin Sung


    Full Text Available Aminoamide local anesthetics induce vasoconstriction in vivo and in vitro. The goals of this in vitro study were to investigate the potency of local anesthetic-induced vasoconstriction and to identify the physicochemical property (octanol/buffer partition coefficient, pKa, molecular weight, or potency of local anesthetics that determines their potency in inducing isolated rat aortic ring contraction. Cumulative concentration-response curves to local anesthetics (levobupivacaine, ropivacaine, lidocaine, and mepivacaine were obtained from isolated rat aorta. Regression analyses were performed to determine the relationship between the reported physicochemical properties of local anesthetics and the local anesthetic concentration that produced 50% (ED50 of the local anesthetic-induced maximum vasoconstriction. We determined the order of potency (ED50 of vasoconstriction among local anesthetics to be levobupivacaine > ropivacaine > lidocaine > mepivacaine. The relative importance of the independent variables that affect the vasoconstriction potency is octanol/buffer partition coefficient > potency > pKa > molecular weight. The ED50 in endothelium-denuded aorta negatively correlated with the octanol/buffer partition coefficient of local anesthetics (r2=0.9563; P<0.001. The potency of the vasoconstriction in the endothelium-denuded aorta induced by local anesthetics is determined primarily by lipid solubility and, in part, by other physicochemical properties including potency and pKa.

  15. Spatially Partitioned Embedded Runge--Kutta Methods

    Ketcheson, David I.


    We study spatially partitioned embedded Runge--Kutta (SPERK) schemes for partial differential equations (PDEs), in which each of the component schemes is applied over a different part of the spatial domain. Such methods may be convenient for problems in which the smoothness of the solution or the magnitudes of the PDE coefficients vary strongly in space. We focus on embedded partitioned methods as they offer greater efficiency and avoid the order reduction that may occur in nonembedded schemes. We demonstrate that the lack of conservation in partitioned schemes can lead to nonphysical effects and propose conservative additive schemes based on partitioning the fluxes rather than the ordinary differential equations. A variety of SPERK schemes are presented, including an embedded pair suitable for the time evolution of fifth-order weighted nonoscillatory spatial discretizations. Numerical experiments are provided to support the theory.

  16. Applicability of Henry's Law to helium solubility in olivine

    Jackson, C.; Parman, S. W.; Kelley, S. P.; Cooper, R. F.


    Applicability of Henry's Law to helium solubility in olivine We have experimentally determined helium solubility in San Carlos olivine across a range of helium partial pressures (PHe) with the goal of quantifying how noble gases behave during partial melting of peridotite. Helium solubility in olivine correlates linearly with PHe between 55 and 1680 bar. This linear relationship suggests Henry's Law is applicable to helium dissolution into olivine up to 1680 bar PHe, providing a basis for extrapolation of solubility relationships determined at high PHe to natural systems. This is the first demonstration of Henry's Law for helium dissolution into olivine. Averaging all the data of the PHe series yields a Henry's coefficient of 3.8(×3.1)×10-12 mol g-1 bar-1. However, the population of Henry's coefficients shows a positive skew (skewness = 1.17), i.e. the data are skewed to higher values. This skew is reflected in the large standard deviation of the population of Henry's coefficients. Averaging the median values from each experiment yields a lower Henry's coefficient and standard deviation: 3.2(× 2.3)×10-12 mol g-1 bar-1. Combining the presently determined helium Henry's coefficient for olivine with previous determinations of helium Henry's coefficients for basaltic melts (e.g. 1) yields a partition coefficient of ~10-4. This value is similar to previous determinations obtained at higher PHe (2). The applicability of Henry's Law here suggests helium is incorporated onto relatively abundant sites within olivine that are not saturated by 1680 bar PHe or ~5×10-9 mol g-1. Large radius vacancies, i.e. oxygen vacancies, are energetically favorable sites for noble gas dissolution (3). However, oxygen vacancies are not abundant enough in San Carlos olivine to account for this solubility (e.g. 4), suggesting the 3x10-12 mol g-1 bar-1 Henry's coefficient is associated with interstitial dissolution of helium. Helium was dissolved into olivine using an externally heated

  17. The Solubility Parameters of Ionic Liquids

    Andrzej Marciniak


    Full Text Available The Hildebrand’s solubility parameters have been calculated for 18 ionic liquids from the inverse gas chromatography measurements of the activity coefficients at infinite dilution. Retention data were used for the calculation. The solubility parameters are helpful for the prediction of the solubility in the binary solvent mixtures. From the solubility parameters, the standard enthalpies of vaporization of ionic liquids were estimated.

  18. 多溴代联苯醚及其代谢产物的正辛醇-空气分配系数的预测模型❉%Predicting the n-octanol/air partitioning coefficients of selected polybrominated diphenyl ethers and their metabolites

    于海瀛; 陈伟; 梁淳淳; 袁泉; 林红军; 陈建荣


    基于目前多溴代联苯醚( PBDEs)及其代谢产物羟基多溴代联苯醚( HO-PBDEs)和甲氧基多溴代联苯醚(MeO-PBDEs)类物质的正辛醇-空气分配系数(KOA)值严重缺乏的现状,使用量子化学方法,建立了PBDEs及其代谢产物的log KOA预测模型,并分析了影响该类物质在正辛醇相和空气相间分配的分子结构参数。所建立的模型具有良好的统计学性能,可以用于同系列物质的log KOA的预测,进而为该类物质的生态风险评价提供基础数据。%Polybrominated diphenyl ethers ( PBDEs) was originally designed as essentially inert flame retard-ants and had become wide-spread contaminants in environment.They could be transformed to hydroxylated PBDEs and methoxylated PBDEs through biological metabolism or oxidation by hydroxyl radicals in the atmos-phere.These chemicals were persistent in environment, and had bioaccumulation and multiple endocrine-dis-rupting effects, resulted in adverse impact on ecological safety and human health.However, the n-octanol/air partition coefficient, KOA , which was recognized as the key descriptor to model the partitioning of chemicals between environmental organic phases and air, had been lacking for PBDEs and their metabolites.Thus it was developed a new prediction model for log KOA employing quantum chemical approach and identified the impor-tant molecular structure parameters that could govern their partition behavior between n-octanol and air.The derived model had good fitting performance and robustness, and could be used to predict the log KOA values of the other PBDEs and HO/MeO-PBDE congeners.

  19. Partitive descriptions in Korean

    Keun Young Shin


    Full Text Available This paper examines Korean partitive constructions to investigate the typology of the partitive structure. In Korean, a quantifier precedes the nominal in a non-partitive, but it follows the nominal in a partitive. The relative order between a quantifier and its associated nominal indicates that a quantifier in Korean partitive does not function as a NP adjunct but takes a DP as its argument. I argue that Korean postnominal (floating quantifier constructions can be interpreted as partitives or pseudo-partitives/quantitatives because a postnominal (floating quantifier denoting a part-of relation can occur with a kind-denoting DP as well as a definite DP. I also propose that a quantifier denoting a part-of relation is associated with the argument of a verb via composition with a verbal predicate in the floating quantifier construction. This approach can provide an account for several idiosyncratic properties of floating quantifier constructions, which are difficult to capture under the assumption that a floating quantifier construction is derived by moving a quantifier away from its associated nominal. This article is part of the Special Collection: Partitives

  20. Experimental Study on the Solubility of Cr2+ in Olivine,Orthopyroxene and Spinel Solid Solutions


    Experiments have been performed on the system MgO-SiO2-Cr-O at 0-2.88 GPa and 1100-1450℃,focusing on the stability of Cr2+ in olivine(O1),orthopyroxene(Opx) and spinel(Sp) and its partitioning between these phases.Analytical reagent grade chemicals,MgO,SiO2,Cr2O3.and Cr were used to make starting mixtures.Excess Cr(50%) was then added in these mixtures to ensure that the resultant phases were in equilibrium with the metal Cr.Flux of BaO+B2O3(%) was added for facilitating experimental equilibrium and crystal growth.Cr was used as capsule material.All phases in the product were identified by X-ray and analyzed by electron microprobe,The contents of CrO in the different phases(O1,Opx and Sp)were calculated according to stoichiometry.The obtained results of calculation indicate that Cr3+ in Ol and Opx is negligible.The experimental results show;(a) with increasing temperature and decreasing pressure,Cr2+ solubility in Ol,Opx and Sp increases;(b) with in creasing temperature,the partitioning coefficient of Mg and Cr2+ between Ol and Opx decreases,that between Opx and Sp increases,and that between Ol and Sp remains almost unchanged;(c) the effect of pressure on all partitioning coefficients is negligible.

  1. Combinatorics of set partitions

    Mansour, Toufik


    Focusing on a very active area of mathematical research in the last decade, Combinatorics of Set Partitions presents methods used in the combinatorics of pattern avoidance and pattern enumeration in set partitions. Designed for students and researchers in discrete mathematics, the book is a one-stop reference on the results and research activities of set partitions from 1500 A.D. to today. Each chapter gives historical perspectives and contrasts different approaches, including generating functions, kernel method, block decomposition method, generating tree, and Wilf equivalences. Methods and d

  2. Soluble NCAM

    Secher, Thomas


    The neural cell adhesion molecule (NCAM) is a membrane-bound glycoprotein involved in homophilic interactions that facilitate cell-cell adhesion. In addition to a number of membrane-bound isoforms, NCAM also exists in several soluble isoforms that have been identified in cerebrospinal fluid, bloo...

  3. Fuzzy Partition Models for Fitting a Set of Partitions.

    Gordon, A. D.; Vichi, M.


    Describes methods for fitting a fuzzy consensus partition to a set of partitions of the same set of objects. Describes and illustrates three models defining median partitions and compares these methods to an alternative approach to obtaining a consensus fuzzy partition. Discusses interesting differences in the results. (SLD)

  4. Bosonic Partition Functions

    Kellerstein, M; Verbaarschot, J J M


    The behavior of quenched Dirac spectra of two-dimensional lattice QCD is consistent with spontaneous chiral symmetry breaking which is forbidden according to the Coleman-Mermin-Wagner theorem. One possible resolution of this paradox is that, because of the bosonic determinant in the partially quenched partition function, the conditions of this theorem are violated allowing for spontaneous symmetry breaking in two dimensions or less. This goes back to work by Niedermaier and Seiler on nonamenable symmetries of the hyperbolic spin chain and earlier work by two of the auhtors on bosonic partition functions at nonzero chemical potential. In this talk we discuss chiral symmetry breaking for the bosonic partition function of QCD at nonzero isospin chemical potential and a bosonic random matrix theory at imaginary chemical potential and compare the results with the fermionic counterpart. In both cases the chiral symmetry group of the bosonic partition function is noncompact.

  5. Carbon partitioning in photosynthesis.

    Melis, Anastasios


    The work seeks to raise awareness of a fundamental problem that impacts the renewable generation of fuels and chemicals via (photo)synthetic biology. At issue is regulation of the endogenous cellular carbon partitioning between different biosynthetic pathways, over which the living cell exerts stringent control. The regulation of carbon partitioning in photosynthesis is not understood. In plants, microalgae and cyanobacteria, methods need be devised to alter photosynthetic carbon partitioning between the sugar, terpenoid, and fatty acid biosynthetic pathways, to lower the prevalence of sugar biosynthesis and correspondingly upregulate terpenoid and fatty acid hydrocarbons production in the cell. Insight from unusual but naturally occurring carbon-partitioning processes can help in the design of blueprints for improved photosynthetic fuels and chemicals production.

  6. 鸦胆子油油水分配系数及其乳剂大鼠在体肠吸收特性研究%O/W partition coefficient of brucea javanica oil and absorption characteristics of its emulsion in rat intestine in situ

    陈钢; 张晓; 卢刚; 刘广泉; 曾洁; 李晔; 魏少阳


    目的:测定鸦胆子油的油水分配系数,并考察鸦胆子油乳在大鼠的肠吸收性质及机制.方法:采用经典摇瓶法测定鸦胆子油的油水分配系数(P);采用在体单向肠灌流法模型研究不同浓度鸦胆子油乳在大鼠的十二指肠、空肠、回肠及结肠的吸收情况,并测定其吸收速率常数(Ka)、吸收率(Fa)和表观渗透系数(Papp).结果:鸦胆子油疏水常数logP的平均值为1.193.鸦胆子油乳在小肠(十二指肠、空肠、回肠)吸收较好,在结肠吸收较少且不规则.其Ka、Fa和Papp按十二指肠、空肠、回肠依次下降且差异显著(P<0.05),不同浓度在同一肠段随着浓度增加,吸收也随之增加,高浓度与低浓度相比,Fa和Papp差异显著(P<0.05),Ka没有显著性差异.结论:鸦胆子油透过生物膜的能力较强.鸦胆子油乳在十二指肠吸收最佳,在小肠内的吸收为一级动力学过程,并无自身浓度抑制作用,可能主要为被动转运机制.%Objective: To determine the O/W partition coefficient of brucea javanica oil and investigate the absorption characteristics and mechanism of its emulsion in rat intestine. Methods: The shake-flask method was employed to determine the O/W partition coefficient ( P) of brucea javanica oil. The absorptions of six concentrations of brucea javanica oil emulsion in different intestinal segments were studied by in situ rats single pass perfusion model, and the absorption rate constant (Ka), absorption rate (Fa) and apparent permeability coefficients (Papp) were determined. Results: The logP of brucea javanica oil was 1.193. Brucea javanica oil emulsion was absorbed at all intestinal segments. However, the absorption of small intestine was better than that of colon. The Ka, Fa and Papp of various intestinal segments decreased in rums in duodenum, jejunum and ileum (P< 0.05). Drug concentration had little significant effect on the Ka in the same intestinal segment. The uptake of the drug

  7. Apparent Oil/water Partition Coefficient of 20(S)-PPD and Its Intestinal Absorption in Rats%20(S)-原人参二醇油水分配系数测定和大鼠在体肠吸收的研究

    王冰; 王玉芹; 浦益琼; 徐本亮; 陶建生; 张彤


    目的 测定20(S)-原人参二醇[20 (S) -PPD]表现油水分配系数,并研究其在体肠吸收机理.方法 利用高效液相色谱法测定20 (S) -PPD浓度,采用摇瓶法测定其表观油水分配系数.采用大鼠在体单向肠灌流实验,按重量法计算动力学参数.结果 37℃条件下,20 (S) -PPD在正辛醇饱和水相中的表观油水分配系数为(1ogPapp=1.72),在不同pH磷酸盐缓冲液中的表观油水分配系数与水相中数值接近.20 (S)-PPD在整个肠段都有吸收,吸收速率常数按大小依次为十二指肠、空肠、回肠、结肠,结肠段的Ka和PApp与其他肠段比较相对较小,说明20 (S) -PPD的主要吸收部位在小肠.结论 不同pH值的介质对20 (S) -PPD表观油水分配系数影响不大;20 (S)-PPD在整个肠段均有良好的吸收,小肠为主要吸收部位.在该药物开发方面,应设法延长其在小肠内的滞留时间,以提高生物利用度.%Objective To determine the apparent oil/water partition coefficient of 20(S)-PPD and to investigate its absorption mechanism by in situ perfusion method in rat intestines. Methods The concentration of 20(S)-PPD was determined by HPLC. A shake flask method was established to determine oil/water partition coefficient of 20(S)-PPD. In situ perfused rat intestinal model was used to calculate the kinetic parameters by weight methods. Results At 37 ℃, the log Papp of 20(S)-PPD in octanol/water system was 1.72. Log Papp in different phosphate buffer solutions were close to that in aqueous phase. 20(S)-PPD was well absorbed in general intestinal tract, where its absorption rate constant (Ka) was duodenum>jejunum>ileum>colon. Ka and Papp in rat colon was relatively lower than in other intestinal tracts. It implied that the main absorption segment of 20(S)-PPD was small intestine. Conclusion The pH of buffer solution had no influence on its distribution coefficient. 20(S)-PPD was well absorbed in general intestinal tract with small intestine as

  8. Estimating Uranium Partition Coefficients from Laboratory Adsorption Isotherms

    Hull, L.C. (INEEL); Grossman, C.; Fjeld, R.A.; Coates, J.T.; Elzerman, A.W. (Clemson University)


    An estimated 330 metric tons of uranium have been buried in the radioactive waste Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL). An assessment of uranium transport parameters is being performed to decrease the uncertainty in risk and dose predictions derived from computer simulations of uranium fate and transport to the underlying Snake River Plain Aquifer. Uranium adsorption isotherms have been measured in the laboratory and fit with a Freundlich isotherm. The Freundlich n parameter was statistically identical for 14 sediment samples. The Freundlich Kf for seven samples, where material properties have been measured, is correlated to sediment surface area. Based on these empirical observations, a model has been derived for adsorption of uranium on INEEL sedimentary materials using surface complexation theory. The model was then used to predict the range of adsorption conditions to be expected at the SDA. Adsorption in the deep vadose zone is predicted to be stronger than in near-surface sediments because the total dissolved carbonate decreases with depth.

  9. Thermodynamics of partitioning of a series of chlorobenzenes to fish storage lipids

    Wezel, A.P. van; Opperhuizen, A. [National Inst. for Coastal and Marine Management, The Hague (Netherlands)]|[Utrecht Univ. (Netherlands)


    Lipid/water partition coefficients for storage lipids from the African catfish (Clarias gariepinus) (K{sub d,sl}) were determined for a series of chlorobenzenes at three different temperatures. k{sub d,sl} values were higher than lipid/water partition coefficients for phospholipids, that were measured previously for the same compounds. Based on results of the present study and studies reported in the literature, it is concluded that fish lipids cannot be considered as a uniform compartment. The distinct properties of the various-lipids result in different lipid/water partition coefficients. The partitioning of chlorobenzenes between storage lipid and water is enthalpy-driven. The entropy of the transfer from water to lipids is unfavorable for the tested compounds. The thermodynamics of partitioning of chlorobenzenes to storage lipids is compared with literature data on the thermodynamics of partitioning to phospholipids, n-octanol and biota.

  10. Dye solubility in supercritical carbon dioxide fluid

    Yan Jun


    Full Text Available Supercritical carbon dioxide fluid is an alternative solvent for the water of the traditional dyeing. The solubility of dyestuff affects greatly the dyeing process. A theoretical model for predicting the dye solubility is proposed and verified experimentally. The paper concludes that the pressure has a greater impact on the dyestuff solubility than temperature, and an optimal dyeing condition is suggested for the highest distribution coefficient of dyestuff.

  11. Fluid-melt partitioning of sulfur in differentiated arc magmas and the sulfur yield of explosive volcanic eruptions

    Masotta, M.; Keppler, H.; Chaudhari, A.


    The fluid-melt partitioning of sulfur (DSfluid/melt) in differentiated arc magmas has been experimentally investigated under oxidizing conditions (Re-ReO2 buffer) from 800 to 950 °C at 200 MPa. The starting glasses ranged in composition from trachyte to rhyolite and were synthesized targeting the composition of the residual melt formed after 10-60% crystallization of originally trachy-andesitic, dacitic and rhyodacitic magmas (Masotta and Keppler, 2015). Fluid compositions were determined both by mass balance and by Raman spectroscopy of fluid inclusions. DSfluid/melt increases exponentially with increasing melt differentiation, ranging from 2 to 15 in the trachytic melt, from 20 to 100 in the dacitic and rhyodacitic melts and from 100 to 120 in the rhyolitic melt. The variation of the DSfluid/melt is entirely controlled by the compositional variation of the silicate melt, with temperature having at most a minor effect within the range investigated. Experiments from this study were used together with data from the literature to calibrate the following model that allows predicting DSfluid/melt for oxidized arc magmas: where nbo/t is the non-bridging oxygen atoms per tetrahedron, ASI is the alumina saturation index, Al# and Ca# are two empirical compositional parameters calculated in molar units (Al # = XAl2O3/XSiO2 +XTiO2 +XAl2O3 and Ca # = XCaO/XNa2O +XK2O). The interplay between fluid-melt partitioning and anhydrite solubility determines the sulfur distribution among anhydrite, melt and fluid. At increasing melt polymerization, the exponential increase of the partition coefficient and the decrease of anhydrite solubility favor the accumulation of sulfur either in the fluid phase or as anhydrite. On the other hand, the higher anhydrite solubility and lower partition coefficient for less polymerized melts favor the retention of sulfur in the melt. At equilibrium conditions, these effects yield a maximum of the sulfur fraction in the fluid phase for slightly

  12. Predicting n-Octanol/Water Partition Coefficients of Polychlorinated Dibenzofurans with Artificial Neural Network%人工神经网络预测多氯代二苯并呋喃类化合物的正辛醇/水分配系数



    The structure parameters of the quantum chemistry for polychlorinated dibenzofurans (PCD-Fs) compounds were calculated by using the MOP AC-AMI method in Chemoffice 8. 0. Some parameters are selected as the structure descriptors of PCDFs compounds. The molecular structures and the model of w-octanol/water partition coefficients are constructed and predicted in terms of back-propagation network and radial basis function networks in artificial neural network. These results are compared with the results of multiple regression methods. It can be found that the results of back-propagation network and radial basis function networks are better than those of multiple regression methods.%采用Chemoffice8.0中的MOPAC-AM1算法对多氯代二苯并呋喃类(PCDFs)化合物的量子化学结构参数进行计算,并将筛选后的量化参数作为PCDFs分子的结构描述符.利用人工神经网络中的反向传播网络和径向基函数网络,建立分子结构与正辛醇/水分配系数间的相关模型并进行预测.将所得结果与多元回归方法的结果进行对比分析,发现反向传播网络和径向基函数网络所得结果均优于多元回归方法.

  13. Partition Function of Spacetime

    Makela, Jarmo


    We consider a microscopic model of spacetime, where spacetime is assumed to be a specific graph with Planck size quantum black holes on its vertices. As a thermodynamical system under consideration we take a certain uniformly accelerating, spacelike two-surface of spacetime which we call, for the sake of brevity and simplicity, as {\\it acceleration surface}. Using our model we manage to obtain an explicit and surprisingly simple expression for the partition function of an acceleration surface. Our partition function implies, among other things, the Unruh and the Hawking effects. It turns out that the Unruh and the Hawking effects are consequences of a specific phase transition, which takes place in spacetime, when the temperature of spacetime equals, from the point of view of an observer at rest with respect to an acceleration surface, to the Unruh temperature measured by that observer. When constructing the partition function of an acceleration surface we are forced to introduce a quantity which plays the ro...

  14. Partition density functional theory

    Nafziger, Jonathan

    Partition density functional theory (PDFT) is a method for dividing a molecular electronic structure calculation into fragment calculations. The molecular density and energy corresponding to Kohn Sham density-functional theory (KS-DFT) may be exactly recovered from these fragments. Each fragment acts as an isolated system except for the influence of a global one-body 'partition' potential which deforms the fragment densities. In this work, the developments of PDFT are put into the context of other fragment-based density functional methods. We developed three numerical implementations of PDFT: One within the NWChem computational chemistry package using basis sets, and the other two developed from scratch using real-space grids. It is shown that all three of these programs can exactly reproduce a KS-DFT calculation via fragment calculations. The first of our in-house codes handles non-interacting electrons in arbitrary one-dimensional potentials with any number of fragments. This code is used to explore how the exact partition potential changes for different partitionings of the same system and also to study features which determine which systems yield non-integer PDFT occupations and which systems are locked into integer PDFT occupations. The second in-house code, CADMium, performs real-space calculations of diatomic molecules. Features of the exact partition potential are studied for a variety of cases and an analytical formula determining singularities in the partition potential is derived. We introduce an approximation for the non-additive kinetic energy and show how this quantity can be computed exactly. Finally a PDFT functional is developed to address the issues of static correlation and delocalization errors in approximations within DFT. The functional is applied to the dissociation of H2 + and H2.

  15. Matrix string partition function

    Kostov, Ivan K; Kostov, Ivan K.; Vanhove, Pierre


    We evaluate quasiclassically the Ramond partition function of Euclidean D=10 U(N) super Yang-Mills theory reduced to a two-dimensional torus. The result can be interpreted in terms of free strings wrapping the space-time torus, as expected from the point of view of Matrix string theory. We demonstrate that, when extrapolated to the ultraviolet limit (small area of the torus), the quasiclassical expressions reproduce exactly the recently obtained expression for the partition of the completely reduced SYM theory, including the overall numerical factor. This is an evidence that our quasiclassical calculation might be exact.

  16. Distributed Evolutionary Graph Partitioning

    Sanders, Peter


    We present a novel distributed evolutionary algorithm, KaFFPaE, to solve the Graph Partitioning Problem, which makes use of KaFFPa (Karlsruhe Fast Flow Partitioner). The use of our multilevel graph partitioner KaFFPa provides new effective crossover and mutation operators. By combining these with a scalable communication protocol we obtain a system that is able to improve the best known partitioning results for many inputs in a very short amount of time. For example, in Walshaw's well known benchmark tables we are able to improve or recompute 76% of entries for the tables with 1%, 3% and 5% imbalance.

  17. Permeation of halide anions through phospholipid bilayers occurs by the solubility-diffusion mechanism

    Paula, S.; Volkov, A. G.; Deamer, D. W.


    Two alternative mechanisms are frequently used to describe ionic permeation of lipid bilayers. In the first, ions partition into the hydrophobic phase and then diffuse across (the solubility-diffusion mechanism). The second mechanism assumes that ions traverse the bilayer through transient hydrophilic defects caused by thermal fluctuations (the pore mechanism). The theoretical predictions made by both models were tested for halide anions by measuring the permeability coefficients for chloride, bromide, and iodide as a function of bilayer thickness, ionic radius, and sign of charge. To vary the bilayer thickness systematically, liposomes were prepared from monounsaturated phosphatidylcholines (PC) with chain lengths between 16 and 24 carbon atoms. The fluorescent dye MQAE (N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide) served as an indicator for halide concentration inside the liposomes and was used to follow the kinetics of halide flux across the bilayer membranes. The observed permeability coefficients ranged from 10(-9) to 10(-7) cm/s and increased as the bilayer thickness was reduced. Bromide was found to permeate approximately six times faster than chloride through bilayers of identical thickness, and iodide permeated three to four times faster than bromide. The dependence of the halide permeability coefficients on bilayer thickness and on ionic size were consistent with permeation of hydrated ions by a solubility-diffusion mechanism rather than through transient pores. Halide permeation therefore differs from that of a monovalent cation such as potassium, which has been accounted for by a combination of the two mechanisms depending on bilayer thickness.

  18. Soluble vs. insoluble fiber

    Insoluble vs. soluble fiber; Fiber - soluble vs. insoluble ... There are 2 different types of fiber -- soluble and insoluble. Both are important for health, digestion, and preventing diseases. Soluble fiber attracts water and turns to gel during digestion. ...

  19. Partitioning of halogens between mantle minerals and aqueous fluids: implications for the fluid flow regime in subduction zones

    Bernini, Diego; Wiedenbeck, Michael; Dolejš, David; Keppler, Hans


    We have performed phase equilibrium experiments in the system forsterite-enstatite-pyrope-H2O with MgCl2 or MgF2 at 1,100 °C and 2.6 GPa to constrain the solubility of halogens in the peridotite mineral assemblage and the fluid-mineral partition coefficients. The chlorine solubility in forsterite, enstatite and in pyrope is very low, 2.1-3.9 and 4.0-11.4 ppm, respectively, and it is independent of the fluid salinity (0.3-30 wt% Cl), suggesting that some intrinsic saturation limit in the crystal is reached already at very low chlorine concentrations. Chlorine is therefore exceedingly incompatible in upper-mantle minerals. The fluorine solubility is 170-336 ppm in enstatite and 510-1,110 ppm in pyrope, again independent of fluid salinity. Forsterite dissolves 1,750-1,900 ppm up to a fluid salinity of 1.6 wt% F. At higher fluorine contents in the system, forsterite is replaced by the minerals of the humite group. The lower solubility of chlorine by three orders of magnitude when compared to fluorine is consistent with increasing lattice strain. Fluid-mineral partition coefficients are 100-102 for fluorine and 103-105 for chlorine. Since the latter values are orders of magnitude higher than those for hydroxyl partitioning, fluid flow from the subducting slab through the mantle wedge will lead to an efficient sequestration of H2O into the nominally anhydrous minerals in the wedge, whereas chlorine becomes enriched in the residual fluid. Simple mass balance calculations reveal that rock-fluid ratios of up to >3,000 are required to produce the elevated Cl/H2O ratios observed in some primitive arc magmas. Accordingly, fluid flow from the subducted slab into the zone of melting in the mantle wedge does not only occur rapidly in narrow channels, but at least in some subduction zones, fluid pervasively infiltrates the mantle peridotite and interacts with a large volume of the mantle wedge. Together with the Cl/H2O ratios of primitive arc magmas, our data therefore constrain

  20. Recommended Partition Coefficient (Kd) Values for Nuclide Partitioning in the Presence of Cellulose Degradation Products

    Serkiz, S.M.


    This report documents the data analysis of the results of the described laboratory studies in order to recommend Kd values for use in Performance Assessment modeling of nuclide transport in the presence of CDP.

  1. Plutonium partitioning in water-granite and water-α-FeOOH systems: from a viewpoint of a three-phase system.

    Lin, Jianfeng; Dang, Haijun; Xie, Jinchuan; Zhou, Guoqing; Li, Mei; Zhang, Jihong


    Traditional sorption experiments commonly treat the colloidal species of low-solubility contaminants as immobile species when separated by centrifugation or ultrafiltration. This study shows that, from a viewpoint of a three-phase system, the mobile Pu species, especially the colloidal species, play an important role in Pu partitioning in water-granite and water-α-FeOOH systems. A new distribution coefficient term Ks/(d+c) was defined to take the mobile colloidal species into consideration, and it differs to the traditional distribution coefficient Ks/d by orders of magnitude in the water-granite and water-α-FeOOH systems. This term, Ks/(d+c), can quantitatively describe Pu partitioning in the suspension, in particular the fraction of mobile species that dominate Pu migration in the environment. The effects of ionic strength (I) and pH on the Pu partitioning in water-granite and water-α-FeOOH systems are well interpreted with respect to the zeta potential change of granite grains, α-FeOOH colloid particles and polymeric Pu. It is concluded that the presence of the α-FeOOH colloid with a low concentration (<10 mg L(-1)) is favorable for the stability of colloidal Pu and leads to large proportion of mobile Pu, especially colloid-associated Pu, which will migrate much faster than dissolved Pu in groundwater.

  2. Ion Association versus Ion Interaction Models in Examining Electrolyte Solutions: Application to Calcium Hydroxide Solubility Equilibrium

    Menéndez, M. Isabel; Borge, Javier


    The heterogeneous equilibrium of the solubility of calcium hydroxide in water is used to predict both its solubility product from solubility and solubility values from solubility product when inert salts, in any concentration, are present. Accepting the necessity of including activity coefficients to treat the saturated solution of calcium…

  3. New Aperture Partitioning Element

    Griffin, S.; Calef, B.; Williams, S.

    Postprocessing in an optical system can be aided by adding an optical element to partition the pupil into a number of segments. When imaging through the atmosphere, the recorded data are blurred by temperature-induced variations in the index of refraction along the line of sight. Using speckle imaging techniques developed in the astronomy community, this blurring can be corrected to some degree. The effectiveness of these techniques is diminished by redundant baselines in the pupil. Partitioning the pupil reduces the degree of baseline redundancy, and therefore improves the quality of images that can be obtained from the system. It is possible to implement the described approach on an optical system with a segmented primary mirror, but not very practical. This is because most optical systems do not have segmented primary mirrors, and those that do have relatively low bandwidth positioning of segments due to their large mass and inertia. It is much more practical to position an active aperture partitioning element at an aft optics pupil of the optical system. This paper describes the design, implementation and testing of a new aperture partitioning element that is completely reflective and reconfigurable. The device uses four independent, annular segments that can be positioned with a high degree of accuracy without impacting optical wavefront of each segment. This mirror has been produced and is currently deployed and working on the 3.6 m telescope.

  4. Partitions with Initial Repetitions

    George E. ANDREWS


    A variety of interesting connections with modular forms, mock theta functions and Rogers-Ramanujan type identities arise in consideration of partitions in which the smaller integers are repeated as summands more often than the larger summands. In particular, this concept leads to new interpre-tations of the Rogers-Selberg identities and Bailey's modulus 9 identities.

  5. Predicting cyclohexane/water distribution coefficients for the SAMPL5 challenge using MOSCED and the SMD solvation model

    Diaz-Rodriguez, Sebastian; Bozada, Samantha M.; Phifer, Jeremy R.; Paluch, Andrew S.


    We present blind predictions using the solubility parameter based method MOSCED submitted for the SAMPL5 challenge on calculating cyclohexane/water distribution coefficients at 298 K. Reference data to parameterize MOSCED was generated with knowledge only of chemical structure by performing solvation free energy calculations using electronic structure calculations in the SMD continuum solvent. To maintain simplicity and use only a single method, we approximate the distribution coefficient with the partition coefficient of the neutral species. Over the final SAMPL5 set of 53 compounds, we achieved an average unsigned error of 2.2± 0.2 log units (ranking 15 out of 62 entries), the correlation coefficient ( R) was 0.6± 0.1 (ranking 35), and 72± 6 % of the predictions had the correct sign (ranking 30). While used here to predict cyclohexane/water distribution coefficients at 298 K, MOSCED is broadly applicable, allowing one to predict temperature dependent infinite dilution activity coefficients in any solvent for which parameters exist, and provides a means by which an excess Gibbs free energy model may be parameterized to predict composition dependent phase-equilibrium.

  6. Hydrologic transport and partitioning of phosphorus fractions

    Berretta, C.; Sansalone, J.


    SummaryPhosphorus (P) in rainfall-runoff partitions between dissolved and particulate matter (PM) bound phases. This study investigates the transport and partitioning of P to PM fractions in runoff from a landscaped and biogenically-loaded carpark in Gainesville, FL (GNV). Additionally, partitioning and concentration results are compared to a similarly-sized concrete-paved source area of a similar rainfall depth frequency distribution in Baton Rouge, LA (BTR), where in contrast vehicular traffic represents the main source of pollutants. Results illustrate that concentrations of P fractions (dissolved, suspended, settleable and sediment) for GNV are one to two orders of magnitude higher than BTR. Despite these differences the dissolved fraction ( f d) and partitioning coefficient ( K d) distributions are similar, illustrating that P is predominantly bound to PM fractions. Examining PM size fractions, specific capacity for P (PSC) indicates that the P concentration order is suspended > settleable > sediment for GNV, similarly to BTR. For GNV the dominant PM mass fraction is sediment (>75 μm), while the mass of P is distributed predominantly between sediment and suspended (<25 μm) fractions since these PM mass fractions dominated the settleable one. With respect to transport of PM and P fractions the predominance of events for both areas is mass-limited first-flush, although each fraction illustrated unique washoff parameters. However, while transport is predominantly mass-limited, the transport of each PM and P fraction is influenced by separate hydrologic parameters.

  7. On partitions avoiding right crossings

    Yan, Sherry H F


    Recently, Chen et al. derived the generating function for partitions avoiding right nestings and posed the problem of finding the generating function for partitions avoiding right crossings. In this paper, we derive the generating function for partitions avoiding right crossings via an intermediate structure of partial matchings avoiding 2-right crossings and right nestings. We show that there is a bijection between partial matchings avoiding 2-right crossing and right nestings and partitions avoiding right crossings.

  8. The Hildebrand Solubility Parameters of Ionic Liquids—Part 2

    Andrzej Marciniak


    Full Text Available The Hildebrand solubility parameters have been calculated for eight ionic liquids. Retention data from the inverse gas chromatography measurements of the activity coefficients at infinite dilution were used for the calculation. From the solubility parameters, the enthalpies of vaporization of ionic liquids were estimated. Results are compared with solubility parameters estimated by different methods.

  9. C-depth method to determine diffusion coefficient and partition coefficient of PCB in building materials

    lIU, Cong; Kolarik, Barbara; Gunnarsen, Lars;


    Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs), due to their resistance to degradation and their bioaccumulation. Before banned in 1970s, the worldwide production of these compounds between 1930 and 1971 is estimated to be 1.5 million tons...

  10. C-depth method to determine diffusion coefficient and partition coefficient of PCB in building materials

    lIU, Cong; Kolarik, Barbara; Gunnarsen, Lars


    Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs), due to their resistance to degradation and their bioaccumulation. Before banned in 1970s, the worldwide production of these compounds between 1930 and 1971 is estimated to be 1.5 million tons......Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs), due to their resistance to degradation and their bioaccumulation. Before banned in 1970s, the worldwide production of these compounds between 1930 and 1971 is estimated to be 1.5 million tons...

  11. High Pressure/Temperature Metal Silicate Partitioning of Tungsten

    Shofner, G. A.; Danielson, L.; Righter, K.; Campbell, A. J.


    The behavior of chemical elements during metal/silicate segregation and their resulting distribution in Earth's mantle and core provide insight into core formation processes. Experimental determination of partition coefficients allows calculations of element distributions that can be compared to accepted values of element abundances in the silicate (mantle) and metallic (core) portions of the Earth. Tungsten (W) is a moderately siderophile element and thus preferentially partitions into metal versus silicate under many planetary conditions. The partitioning behavior has been shown to vary with temperature, silicate composition, oxygen fugacity, and pressure. Most of the previous work on W partitioning has been conducted at 1-bar conditions or at relatively low pressures, i.e. <10 GPa, and in two cases at or near 20 GPa. According to those data, the stronger influences on the distribution coefficient of W are temperature, composition, and oxygen fugacity with a relatively slight influence in pressure. Predictions based on extrapolation of existing data and parameterizations suggest an increased pressured dependence on metal/ silicate partitioning of W at higher pressures 5. However, the dependence on pressure is not as well constrained as T, fO2, and silicate composition. This poses a problem because proposed equilibration pressures for core formation range from 27 to 50 GPa, falling well outside the experimental range, therefore requiring exptrapolation of a parametereized model. Higher pressure data are needed to improve our understanding of W partitioning at these more extreme conditions.

  12. Partitional clustering algorithms


    This book summarizes the state-of-the-art in partitional clustering. Clustering, the unsupervised classification of patterns into groups, is one of the most important tasks in exploratory data analysis. Primary goals of clustering include gaining insight into, classifying, and compressing data. Clustering has a long and rich history that spans a variety of scientific disciplines including anthropology, biology, medicine, psychology, statistics, mathematics, engineering, and computer science. As a result, numerous clustering algorithms have been proposed since the early 1950s. Among these algorithms, partitional (nonhierarchical) ones have found many applications, especially in engineering and computer science. This book provides coverage of consensus clustering, constrained clustering, large scale and/or high dimensional clustering, cluster validity, cluster visualization, and applications of clustering. Examines clustering as it applies to large and/or high-dimensional data sets commonly encountered in reali...

  13. Generalised twisted partition functions

    Petkova, V B


    We consider the set of partition functions that result from the insertion of twist operators compatible with conformal invariance in a given 2D Conformal Field Theory (CFT). A consistency equation, which gives a classification of twists, is written and solved in particular cases. This generalises old results on twisted torus boundary conditions, gives a physical interpretation of Ocneanu's algebraic construction, and might offer a new route to the study of properties of CFT.

  14. BKP plane partitions

    Foda, Omar; Wheeler, Michael [Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3010 (Australia)


    Using BKP neutral fermions, we derive a product expression for the generating function of volume-weighted plane partitions that satisfy two conditions. If we call a set of adjacent equal height-h columns, h > 0, an h-path, then 1. Every h-path can assume one of two possible colours. 2. There is a unique way to move along an h-path from any column to another.

  15. Hadamard partitioned difference families

    Buratti, Marco


    We prove that every Hadamard difference set of order $u^2$ leads to a partitioned difference family of any order $v\\equiv4u^2$ (mod $8u^2$) and blocks of sizes $4u^2-2u$, $4u^2$ and $4u^2+2u$ provided that the maximal prime power divisors of $v\\over4u^2$ are all greater than $4u^2+2u$.

  16. Partitioning of L-methionine in aqueous two-phase systems containing poly(propylene glycol) and sodium phosphate salts

    Salabat, Alireza, E-mail: [Chemistry Department, Arak University, P.O. Box 38156-879, Arak (Iran, Islamic Republic of); Sadeghi, Rahmat [Department of Chemistry, University of Kurdistan, Sanandaj, Kurdistan 66135 (Iran, Islamic Republic of); Moghadam, Somayeh Tiani [Chemistry Department, Arak University, P.O. Box 38156-879, Arak (Iran, Islamic Republic of); Jamehbozorg, Bahman [Department of Chemistry, University of Kurdistan, Sanandaj, Kurdistan 66135 (Iran, Islamic Republic of)


    Highlights: > Thermodynamics parameters for partitioning of L-methionine in ATPS. > Investigation of different effects on partition coefficient of the amino acid. > Propose the best condition for L-methionine partitioning. - Abstract: The partitioning behavior of L-methionine has been studied in aqueous two-phase systems of (poly(propylene glycol) + sodium phosphate salts + H{sub 2}O) at different temperatures. The salts used were sodium di-hydrogen phosphate (NaH{sub 2}PO{sub 4}), di-sodium hydrogen phosphate (Na{sub 2}HPO{sub 4}) and tri-sodium phosphate (Na{sub 3}PO{sub 4}). The effects of tie line length, salt type, and temperature on the partition coefficient of this amino acid have been studied. In addition, thermodynamic parameters ({Delta}H{sup o}, {Delta}S{sup o} and {Delta}G{sup o}) as a function of temperature were calculated. The results showed that increasing tie line length led to decreasing of the partition coefficient. We also showed that the partition coefficients of the amino acid in the systems containing Na{sub 3}PO{sub 4} are greater than the other two salts. Moreover, it is verified that increasing temperature led to decreasing the partition coefficient. The experimental partition coefficient data are correlated using a modified virial-type model.

  17. Environmental Partitioning of Biomass Combustion Biomarkers in Arctic Rivers across the Spring Freshet Hydrograph

    Myers-Pigg, A.; Louchouarn, P.; Tananaev, N.; Teisserenc, R.


    A number of studies have recently documented that pyrogenic carbon (PyC) is an integral and significant proportion of DOM in worldwide rivers, and that this material originates from all fractions of the PyC continuum, from highly resistant PyC to more soluble, labile components. Understanding the transfer of PyC to river systems is paramount for Arctic regions, given the projected increase in frequency and intensity of forest fires in boreal ecosystems. Considering this potential increase in the production of boreal PyC, constraining the PyC-cycle in Arctic environments is essential. However, one of the parameters that affect the fate of PyC in river systems, the environmental partitioning between soluble and particulate phases (Kd), has so far been unstudied. This is particularly important to quantify for low-temperature PyC, due to the greater experimental solubility of this portion of the PyC continuum. Here, we present for the first time a study that analyzes phase partitioning of low-temperature PyC biomarkers in two Arctic Rivers: a small Canadian river, the Great Whale River in northern Quebec, and the largest Arctic River, the Yenisei River in north-central Siberia. During the spring freshet increases in discharge in each river, mass-normalized sorption coefficients (Kd) increase by two orders of magnitude, whereas organic carbon-normalized sorption coefficients (KOC) vary by a much smaller range. The former trend implies that spring discharge events export potentially fresher materials in the sorbed fractions, as the PyC components may not yet have fully equilibrated with the aqueous phase. The latter observation suggests an association of combustion biomarkers with particulate organic matter (char particles or sorbed soil organic matter). The present work confirms that low temperature PyC biomarkers sorb to particles at a high enough level to enter sedimentary deposits and record wildfire signatures. However, the Kd-KOC values for these rivers are 3

  18. In-Situ Characterization of Dense Non-Aqueous Phase Liquids Using Partitioning Tracers

    Gary A. Pope; Daene C. McKinney; Akhil Datta Gupta; Richard E. Jackson; Minquan Jin


    Majors advances have been made during the past three years in our research on interwell partitioning tracers tests (PITTs). These advances include (1) progress on the inverse problem of how to estimate the three-dimensional distribution of NAPL in aquifers from the tracer data, (2) the first ever partitioning tracer experiments in dual porosity media, (3) the first modeling of partitioning tracers in dual porosity media (4) experiments with complex NAPLs such as coal tar, (5) the development of an accurate and simple method to predict partition coefficients using the equivalent alkane carbon number approach, (6) partitioning tracer experiments in large model aquifers with permeability layers, (7) the first ever analysis of partitioning tracer data to estimate the change in composition of a NAPL before and after remediation (8) the first ever analysis of partitioning tracer data after a field demonstration of surfactant foam to remediate NAPL and (9) experiments at elevated temperatures .


    Lead (Pb) and cadmium (Cd) are two of the most common toxicants found in contaminated environments. Because solubilization of these metallic elements from the solid phase can influence their fate, transport and bioavailability, the partitioning coefficient (Kd) for these metals ...

  20. Volatile Solubilities in Mt. Somma-Vesuvius Phonolite Melt and New Insights on Degassing of Sulfur, Chlorine, and Water

    Webster, J. D.; Sintoni, M. F.; de Vivo, B.; Lima, A.


    To better understand volatile exsolution, degassing, and eruptive processes in subduction-related magmas, we have conducted thirty H2O plus S plus Cl solubility experiments with phonolite melt at 905 to 1000 deg. C, 200 MPa, and relatively oxidizing conditions. The experiments include an 8000-year old Mt. Somma-Vesuvius phonolite, distilled H2O, NaCl, KCl, and CaSO4, and they involve a new method of constraining the concentration of S in the run-product fluids. Unlike prior S-solubility experiments, the S concentration in fluid is determined as proportional to the mass loss of the anhydrite crystals in the starting charges of the experiments. This method provides accurate S contents of fluids. The H2O, Cl, and S concentrations of the phonolitic glasses of our experiments range from 4 to 8, 0.38 to 0.84, and 0.01 to 0.19 wt.%, respectively. Sulfur solubility increases with increasing CaO and FeO (total iron) in melt, decreasing Cl and K2O in melt, decreasing Cl in fluid(s), and with increasing oxygen fugacity values greater than NNO. Chlorine solubility in melt increases with decreasing S content of melt and decreasing S and H2O in the coexisting fluid(s). Water solubility in melt shows no systematic variation with melt composition, but varies strongly with the composition of fluids. The partition coefficients (wt.% of X in fluid[s]/wt.% of X in phonolitic melt) range from 40 to > 200 for S and from 12 to 87 for Cl. At pressure-temperature-oxygen fugacity conditions similar to those of this study, these partition coefficients are equivalent to those determined previously for natural equilibria involving andesite melt plus Cl-free, S-bearing aqueous fluid (Scaillet and Pichavant, 2003) and experimental equilibria with andesite melt plus S-free, Cl-bearing aqueous fluid (Webster et al., 1999), respectively. Our research also shows that these partition coefficients for S and Cl are inversely proportional to one another. Silicate melt inclusions in pyroxene phenocrysts

  1. Rational Design of Molecular Gelator - Solvent Systems Guided by Solubility Parameters

    Lan, Yaqi

    Self-assembled architectures, such as molecular gels, have attracted wide interest among chemists, physicists and engineers during the past decade. However, the mechanism behind self-assembly remains largely unknown and no capability exists to predict a priori whether a small molecule will gelate a specific solvent or not. The process of self-assembly, in molecular gels, is intricate and must balance parameters influencing solubility and those contrasting forces that govern epitaxial growth into axially symmetric elongated aggregates. Although the gelator-gelator interactions are of paramount importance in understanding gelation, the solvent-gelator specific (i.e., H-bonding) and nonspecific (dipole-dipole, dipole-induced and instantaneous dipole induced forces) intermolecular interactions are equally important. Solvent properties mediate the self-assembly of molecular gelators into their self-assembled fibrillar networks. Herein, solubility parameters of solvents, ranging from partition coefficients (logP), to Henry's law constants (HLC), to solvatochromic ET(30) parameters, to Kamlet-Taft parameters (beta, alpha and pi), to Hansen solubility parameters (deltap, deltad, deltah), etc., are correlated with the gelation ability of numerous classes of molecular gelators. Advanced solvent clustering techniques have led to the development of a priori tools that can identify the solvents that will be gelled and not gelled by molecular gelators. These tools will greatly aid in the development of novel gelators without solely relying on serendipitous discoveries.

  2. Predicting the partitioning of biological compounds between room-temperature ionic liquids and water by means of the solvation-parameter model.

    Padró, Juan M; Ponzinibbio, Agustín; Mesa, Leidy B Agudelo; Reta, Mario


    The partition coefficients, P(IL/w), for different probe molecules as well as for compounds of biological interest between the room-temperature ionic liquids (RTILs) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF(6)], 1-hexyl-3-methylimidazolium hexafluorophosphate, [HMIM][PF(6)], 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF(4)] and water were accurately measured. [BMIM][PF(6)] and [OMIM][BF(4)] were synthesized by adapting a procedure from the literature to a simpler, single-vessel and faster methodology, with a much lesser consumption of organic solvent. We employed the solvation-parameter model to elucidate the general chemical interactions involved in RTIL/water partitioning. With this purpose, we have selected different solute descriptor parameters that measure polarity, polarizability, hydrogen-bond-donor and hydrogen-bond-acceptor interactions, and cavity formation for a set of specifically selected probe molecules (the training set). The obtained multiparametric equations were used to predict the partition coefficients for compounds not present in the training set (the test set), most being of biological interest. Partial solubility of the ionic liquid in water (and water into the ionic liquid) was taken into account to explain the obtained results. This fact has not been deeply considered up to date. Solute descriptors were obtained from the literature, when available, or else calculated through commercial software. An excellent agreement between calculated and experimental log P(IL/w) values was obtained, which demonstrated that the resulting multiparametric equations are robust and allow predicting partitioning for any organic molecule in the biphasic systems studied.

  3. Relationship between swelling of hydroxypropylmethylcellulose and the Hansen and Karger partial solubility parameters.

    Navarro-Lupión, Francisco-Javier; Bustamante, Pilar; Escalera, Begoña


    A model that relates the equilibrium swelling of hydroxypropylmethylcellulose to the partial solubility parameters of both the polymer and the solvents is proposed to interpret and correlate the experimental data. The non-specific interactions are expressed as the dispersion delta(d) and polar delta(p) solubility parameters of Hansen, or as a combination of both. Hydrogen bonding is represented by the acidic delta(a) and the basic delta(b) Karger solubility parameters. The results are compared with models including the same parameters for non-specific interactions (delta(d) and delta(p)) and the Hansen hydrogen bonding parameter delta(h). Equilibrium swelling of this hydrophilic polymer that is widely used in drug formulation is measured in pure solvents covering a wide polarity range. In a qualitative way, swelling increases in solvents with higher Hildebrand solubility parameters and stronger hydrogen bonding capability, and it decreases in non-polar solvents. Single polarity indexes, such as the Hildebrand solubility parameter or the partition coefficient (PC), do not fit well the overall experimental data. The best correlations were obtained with the proposed model, providing at the same time an interpretation consistent with the physical meaning of the terms included in the equation. Swelling increases as the non-specific interactions of the polymer and the solvents become alike, and as the Lewis acid-base interactions of the polymer (1) and the solvent (2) represented by the products delta(1a)delta(2b) and delta(1b)delta(2a) become greater. Conversely, hydrogen bonding self association of the solvents (the product delta(1a)delta(1b)) lowers swelling. The results show that the Karger hydrogen bonding parameters provide a better approach than the Hansen hydrogen bonding parameter to correlate the swelling behavior of a hydrophilic polymer. (c) 2005 Wiley-Liss, Inc.

  4. Partitioning the Quaternary

    Gibbard, Philip L.; Lewin, John


    We review the historical purposes and procedures for stratigraphical division and naming within the Quaternary, and summarize the current requirements for formal partitioning through the International Commission on Stratigraphy (ICS). A raft of new data and evidence has impacted traditional approaches: quasi-continuous records from ocean sediments and ice cores, new numerical dating techniques, and alternative macro-models, such as those provided through Sequence Stratigraphy and Earth-System Science. The practical usefulness of division remains, but there is now greater appreciation of complex Quaternary detail and the modelling of time continua, the latter also extending into the future. There are problems both of commission (what is done, but could be done better) and of omission (what gets left out) in partitioning the Quaternary. These include the challenge set by the use of unconformities as stage boundaries, how to deal with multiphase records in ocean and terrestrial sediments, what happened at the 'Early-Mid- (Middle) Pleistocene Transition', dealing with trends that cross phase boundaries, and the current controversial focus on how to subdivide the Holocene and formally define an 'Anthropocene'.

  5. Experimental study of radium partitioning between anorthite and melt at 1 atm

    Miller, S; Burnett, D; Asimow, P; Phinney, D; Hutcheon, I


    We present the first experimental radium mineral/melt partitioning data, specifically between anorthite and a CMAS melt at atmospheric pressure. Ion microprobe measurement of coexisting anorthite and glass phases produces a molar D{sub Ra} = 0.040 {+-} 0.006 and D{sub Ra}/D{sub Ba} = 0.23 {+-} 0.05 at 1400 C. Our results indicate that lattice strain partitioning models fit the divalent (Ca, Sr, Ba, Ra) partition coefficient data of this study well, supporting previous work on crustal melting and magma chamber dynamics that has relied on such models to approximate radium partitioning behavior in the absence of experimentally determined values.

  6. The Effect of pH Difference Between Two Phases on the Partition of Lysozyme in Aqueous Two-Phase System


    In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases, and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.

  7. Molecular Thermodynamic Modeling of Mixed Solvent Solubility

    Ellegaard, Martin Dela; Abildskov, Jens; O’Connell, John P.


    A method based on statistical mechanical fluctuation solution theory for composition derivatives of activity coefficients is employed for estimating dilute solubilities of 11 solid pharmaceutical solutes in nearly 70 mixed aqueous and nonaqueous solvent systems. The solvent mixtures range from...... nearly ideal to strongly nonideal. The database covers a temperature range from 293 to 323 K. Comparisons with available data and other existing solubility methods show that the method successfully describes a variety of observed mixed solvent solubility behaviors using solute−solvent parameters from...

  8. The characterization of petroleum contamination in heterogenous media using partitioning tracer method

    Kim, E.; Rhee, S.; Park, J. [Seoul National Univ. (Korea, Republic of). Dept. of Civil and Environmental Engineering


    A partitioning tracer method for characterizing petroleum contamination in heterogenous media was discussed. The average saturation level of nonaqueous phase liquids (NAPLs) was calculated by comparing the transport of the partitioning tracers to a conservative tracer. The NAPL saturation level represented a continuous value throughout the contaminated site. Experiments were conducted in a 2-D sandbox divided into 4 parts using different-sized sands. Soils were contaminated with a mixture of kerosene and diesel. Partitioning tracer tests were conducted both before and after contamination. A partitioning batch test was conducted to determine the partition coefficient (K) of the tracer between the NAPL and water. Breakthrough curves were obtained, and a retardation factor (R) was calculated. Results of the study showed that the calculated NAPL saturation was in good agreement with determined values. It was concluded that the partitioning tracer test is an accurate method of locating and quantifying NAPLs.

  9. Partitioning of Potassium Between Fe-S and K-rich Silicate at High Temperature

    Kamada, S.; Sakai, T.; Ohtani, E.; Kondo, T.; Miyahara, M.; Nishijima, M.; Kikegawa, T.


    Partitioning of potassium between liquid iron and silicate melt at high pressure and temperature is important to estimate the amount of potassium in the Earth's core. In the previous works, the partitioning experiments were performed below 26 GPa using a large volume press (e.g. Ito et al., 1993; Gessmann et al., 2002; Murthy et al., 2003), except for the work by Hirao et al. (2006) using a laser heated diamond anvil cell (LHDAC). The aim of this work is to clarify the effects of pressure, temperature and sulfur content on the partitioning coefficients of potassium (DK) in a wide pressure and temperature range using LHDAC. We performed partitioning experiments at 50 GPa and the temperature range of 2500-3000 K using a LHDAC. The starting material was foil of Fe79S21, which was sandwiched by a natural Aduralia (KAlSi3O8). Powder X-ray diffraction experiments were carried out at the ambient pressure to identify the reaction phases at BL13A and BL18C Photon Factory, KEK. Chemical analysis was performed using EPMA and ATEM (Institute for Materials Research, Tohoku Univ.). DK increases from 0.011 to 0.136 with increasing temperature (2500-3000 K) at 50 GPa. This trend is consistent with previous studies (e.g. Gessmann and Wood, 2002; Murthy et al., 2003). Our result indicates that DK decreases with increasing pressure. DK at 50 GPa and 3000 K in the sulfur- bearing system is larger than that reported by Ito et al.(1993) at 26 GPa and 2900 K in the sulfur-free system. This results show that sulfur may increase the solubility of potassium into metallic iron melt. DK of 0.005-0.12 at 135 GPa and 3000-4000 K is estimated by extrapolation of the DK to the condition of the core-mantle boundary (CMB) using the dependence of temperature and pressure observed in this study. This value suggests that the total potassium content in the core is about 1.2-29 ppm assuming that a primitive mantle concentration of potassium is 240 ppm (McDounough and Sun, 1995). It can produce only the

  10. Determination of descriptors for polycyclic aromatic hydrocarbons and related compounds by chromatographic methods and liquid-liquid partition in totally organic biphasic systems.

    Ariyasena, Thiloka C; Poole, Colin F


    Retention factors on several columns and at various temperatures using gas chromatography and from reversed-phase liquid chromatography on a SunFire C18 column with various mobile phase compositions containing acetonitrile, methanol and tetrahydrofuran as strength adjusting solvents are combined with liquid-liquid partition coefficients in totally organic biphasic systems to calculate descriptors for 23 polycyclic aromatic hydrocarbons and eighteen related compounds of environmental interest. The use of a consistent protocol for the above measurements provides descriptors that are more self consistent for the estimation of physicochemical properties (octanol-water, air-octanol, air-water, aqueous solubility, and subcooled liquid vapor pressure). The descriptor in this report tend to have smaller values for the L and E descriptors and random differences in the B and S descriptors compared with literature sources. A simple atom fragment constant model is proposed for the estimation of descriptors from structure for polycyclic aromatic hydrocarbons. The new descriptors show no bias in the prediction of the air-water partition coefficient for polycyclic aromatic hydrocarbons unlike the literature values.

  11. Gas solubilities widespread applications

    Gerrard, William


    Gas Solubilities: Widespread Applications discusses several topics concerning the various applications of gas solubilities. The first chapter of the book reviews Henr's law, while the second chapter covers the effect of temperature on gas solubility. The third chapter discusses the various gases used by Horiuti, and the following chapters evaluate the data on sulfur dioxide, chlorine data, and solubility data for hydrogen sulfide. Chapter 7 concerns itself with solubility of radon, thoron, and actinon. Chapter 8 tackles the solubilities of diborane and the gaseous hydrides of groups IV, V, and

  12. Partitioning and diffusion of PBDEs through an HDPE geomembrane.

    Rowe, R Kerry; Saheli, Pooneh T; Rutter, Allison


    Polybrominated diphenyl ether (PBDE) has been measured in MSW landfill leachate and its migration through a modern landfill liner has not been investigated previously. To assure environmental protection, it is important to evaluate the efficacy of landfill liners for controlling the release of PBDE to the environment to a negligible level. The partitioning and diffusion of a commercial mixture of PBDEs (DE-71: predominantly containing six congeners) with respect to a high-density polyethylene (HDPE) geomembrane is examined. The results show that the partitioning coefficients of the six congeners in this mixture range from 700,000 to 7,500,000 and the diffusion coefficients range from 1.3 to 6.0×10(-15)m(2)/s depending on the congener. This combination of very high partitioning coefficients and very low diffusion coefficients suggest that a well constructed HDPE geomembrane liner will be an extremely effective barrier for PBDEs with respect to diffusion from a municipal solid waste landfill, as illustrated by an example. The results for pure diffusion scenario showed that the congeners investigated meet the guidelines by at least a factor of three for an effective geomembrane liner where diffusion is the controlling transport mechanism. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Instantons on ALE spaces and orbifold partitions

    Dijkgraaf, Robbert; Sułkowski, Piotr


    We consider Script N = 4 theories on ALE spaces of Ak-1 type. As is well known, their partition functions coincide with Ak-1 affine characters. We show that these partition functions are equal to the generating functions of some peculiar classes of partitions which we introduce under the name 'orbifold partitions'. These orbifold partitions turn out to be related to the generalized Frobenius partitions introduced by G. E. Andrews some years ago. We relate the orbifold partitions to the blended partitions and interpret explicitly in terms of a free fermion system.

  14. Instantons on ALE spaces and orbifold partitions

    Dijkgraaf, Robbert


    We consider N=4 theories on ALE spaces of $A_{k-1}$ type. As is well known, their partition functions coincide with $A_{k-1}$ affine characters. We show that these partition functions are equal to the generating functions of some peculiar classes of partitions which we introduce under the name 'orbifold partitions'. These orbifold partitions turn out to be related to the generalized Frobenius partitions introduced by G. E. Andrews some years ago. We relate the orbifold partitions to the blended partitions and interpret explicitly in terms of a free fermion system.

  15. Partition function zeros of an Ising spin glass

    Damgaard, P H


    We study the pattern of zeros emerging from exact partition function evaluations of Ising spin glasses on conventional finite lattices of varying sizes. A large number of random bond configurations are probed in the framework of quenched averages. This study is motivated by the relationship between hierarchical lattice models whose partition function zeros fall on Julia sets and chaotic renormalization flows in such models with frustration, and by the possible connection of the latter with spin glass behaviour. In any finite volume, the simultaneous distribution of the zeros of all partition functions can be viewed as part of the more general problem of finding the location of all the zeros of a certain class of random polynomials with positive integer coefficients. Some aspects of this problem have been studied in various branches of mathematics, and we show how polynomial mappings which are used in graph theory to classify graphs, may help in characterizing the distribution of zeros. We finally discuss the ...

  16. Approximation methods for the partition functions of anharmonic systems

    Lew, P.; Ishida, T.


    The analytical approximations for the classical, quantum mechanical and reduced partition functions of the diatomic molecule oscillating internally under the influence of the Morse potential have been derived and their convergences have been tested numerically. This successful analytical method is used in the treatment of anharmonic systems. Using Schwinger perturbation method in the framework of second quantization formulism, the reduced partition function of polyatomic systems can be put into an expression which consists separately of contributions from the harmonic terms, Morse potential correction terms and interaction terms due to the off-diagonal potential coefficients. The calculated results of the reduced partition function from the approximation method on the 2-D and 3-D model systems agree well with the numerical exact calculations.

  17. Partitioning ecosystems for sustainability.

    Murray, Martyn G


    Decline in the abundance of renewable natural resources (RNRs) coupled with increasing demands of an expanding human population will greatly intensify competition for Earth's natural resources during this century, yet curiously, analytical approaches to the management of productive ecosystems (ecological theory of wildlife harvesting, tragedy of the commons, green economics, and bioeconomics) give only peripheral attention to the driving influence of competition on resource exploitation. Here, I apply resource competition theory (RCT) to the exploitation of RNRs and derive four general policies in support of their sustainable and equitable use: (1) regulate resource extraction technology to avoid damage to the resource base; (2) increase efficiency of resource use and reduce waste at every step in the resource supply chain and distribution network; (3) partition ecosystems with the harvesting niche as the basic organizing principle for sustainable management of natural resources by multiple users; and (4) increase negative feedback between consumer and resource to bring about long-term sustainable use. A simple policy framework demonstrates how RCT integrates with other elements of sustainability science to better manage productive ecosystems. Several problem areas of RNR management are discussed in the light of RCT, including tragedy of the commons, overharvesting, resource collapse, bycatch, single species quotas, and simplification of ecosystems.


    The soil/sediment adsorption partition coefficient normalized to organic carbon (Koc) is extensively used to assess the fate of organic chemicals in hazardous waste sites. Several attempts have been made to estimate the value of Koc from chemical structure ...


    The soil/sediment adsorption partition coefficient normalized to organic carbon (Koc) is extensively used to assess the fate of organic chemicals in hazardous waste sites. Several attempts have been made to estimate the value of Koc from chemical structure ...

  20. Nonzero Solubility Rule

    尉志武; 周蕊; 刘芸


    A solubility-related rule, nonzero solubility rule, is introduced in this paper. It is complementary to the existing rules such as the "like dissolves like" rule and can be understood on the basis of classical chemical thermodynamics.

  1. Partition functions 1: Improved partition functions and thermodynamic quantities for normal, equilibrium, and ortho and para molecular hydrogen

    Popovas, Andrius


    Aims. In this work we rigorously show the shortcomings of various simplifications that are used to calculate the total internal partition function. These shortcomings can lead to errors of up to 40 percent or more in the estimated partition function. These errors carry on to calculations of thermodynamic quantities. Therefore a more complicated approach has to be taken. Methods. Seven possible simplifications of various complexity are described, together with advantages and disadvantages of direct summation of experimental values. These were compared to what we consider the most accurate and most complete treatment (case 8). Dunham coefficients were determined from experimental and theoretical energy levels of a number of electronically excited states of H$_2$ . Both equilibrium and normal hydrogen was taken into consideration. Results. Various shortcomings in existing calculations are demonstrated, and the reasons for them are explained. New partition functions for equilibrium, normal, and ortho and para hyd...

  2. Partitioning of Nanoparticles into Organic Phases and Model Cells

    Posner, J.D.; Westerhoff, P.; Hou, W-C.


    There is a recognized need to understand and predict the fate, transport and bioavailability of engineered nanoparticles (ENPs) in aquatic and soil ecosystems. Recent research focuses on either collection of empirical data (e.g., removal of a specific NP through water or soil matrices under variable experimental conditions) or precise NP characterization (e.g. size, degree of aggregation, morphology, zeta potential, purity, surface chemistry, and stability). However, it is almost impossible to transition from these precise measurements to models suitable to assess the NP behavior in the environment with complex and heterogeneous matrices. For decades, the USEPA has developed and applies basic partitioning parameters (e.g., octanol-water partition coefficients) and models (e.g., EPI Suite, ECOSAR) to predict the environmental fate, bioavailability, and toxicity of organic pollutants (e.g., pesticides, hydrocarbons, etc.). In this project we have investigated the hypothesis that NP partition coefficients between water and organic phases (octanol or lipid bilayer) is highly dependent on their physiochemical properties, aggregation, and presence of natural constituents in aquatic environments (salts, natural organic matter), which may impact their partitioning into biological matrices (bioaccumulation) and human exposure (bioavailability) as well as the eventual usage in modeling the fate and bioavailability of ENPs. In this report, we use the terminology "partitioning" to operationally define the fraction of ENPs distributed among different phases. The mechanisms leading to this partitioning probably involve both chemical force interactions (hydrophobic association, hydrogen bonding, ligand exchange, etc.) and physical forces that bring the ENPs in close contact with the phase interfaces (diffusion, electrostatic interactions, mixing turbulence, etc.). Our work focuses on partitioning, but also provides insight into the relative behavior of ENPs as either "more like

  3. Partitioning of Nanoparticles into Organic Phases and Model Cells

    Posner, J.D.; Westerhoff, P.; Hou, W-C.


    There is a recognized need to understand and predict the fate, transport and bioavailability of engineered nanoparticles (ENPs) in aquatic and soil ecosystems. Recent research focuses on either collection of empirical data (e.g., removal of a specific NP through water or soil matrices under variable experimental conditions) or precise NP characterization (e.g. size, degree of aggregation, morphology, zeta potential, purity, surface chemistry, and stability). However, it is almost impossible to transition from these precise measurements to models suitable to assess the NP behavior in the environment with complex and heterogeneous matrices. For decades, the USEPA has developed and applies basic partitioning parameters (e.g., octanol-water partition coefficients) and models (e.g., EPI Suite, ECOSAR) to predict the environmental fate, bioavailability, and toxicity of organic pollutants (e.g., pesticides, hydrocarbons, etc.). In this project we have investigated the hypothesis that NP partition coefficients between water and organic phases (octanol or lipid bilayer) is highly dependent on their physiochemical properties, aggregation, and presence of natural constituents in aquatic environments (salts, natural organic matter), which may impact their partitioning into biological matrices (bioaccumulation) and human exposure (bioavailability) as well as the eventual usage in modeling the fate and bioavailability of ENPs. In this report, we use the terminology "partitioning" to operationally define the fraction of ENPs distributed among different phases. The mechanisms leading to this partitioning probably involve both chemical force interactions (hydrophobic association, hydrogen bonding, ligand exchange, etc.) and physical forces that bring the ENPs in close contact with the phase interfaces (diffusion, electrostatic interactions, mixing turbulence, etc.). Our work focuses on partitioning, but also provides insight into the relative behavior of ENPs as either "more like

  4. Partitioning of Organic Compounds into Supercritical CO2 in Depleted Oil Reservoirs - A Review

    Burant, A.; Lowry, G. V.; Karamalidis, A.


    Depleted oil reservoirs, with enhanced oil recovery, will be one of the first adopters of carbon capture and storage (CCS), which is a promising mitigation strategy for global climate change. The large scale implementation of CCS mandates better understanding of the risks associated with CO2 injection, especially in regards to potential leakage of the stored CO2. Organics, in the residual oil and dissolved in the brine, can partition into supercritical CO2 (sc-CO2) and move with that phase if it leaks. This review presents an overview of the thermodynamic models and trends in experimental partitioning data needed to understand what compounds may be expected to move with the sc-CO2. There are two main types of thermodynamic models used for predicting the solubility of organic compounds in sc-CO2, equations of state and quantitative structure activity relationships. Both can predict the partitioning behavior of one compound in sc-CO2, however only equations of state can predict solubility in multicomponent systems. In addition, equations of state have been developed to determine the effect of electrolytes on the partitioning behavior of organics dissolved in brines. There are three main trends in the partitioning behavior of organics in sc-CO2: Pure phase solubility follows trends in vapor pressure; compounds with higher volatility have higher solubility in sc-CO2. Second, the partitioning from water to sc-CO2 follows trends in Henry's constants, which follow the relative solubility of a compound in both the sc-CO2 and aqueous phases. Thirdly, the solubility of a compound can be enhanced by the presence of another; highly volatile compounds enhance the solubility of compounds with lower volatility. Finally, the review presents the gaps in experimental research that can be used to improve the modeling of the partitioning behavior of organics in sc-CO2, specifically in regards to co-solvency effects and the effects of electrolytes on the partitioning of dissolved

  5. A general method to study equilibrium partitioning of macromolecules

    The distribution of macromolecules between a confined microscopic solution and a macroscopic bulk solution plays an important role in understanding separation processes such as Size Exclusion Chromatography (SEC). In this study, we have developed an efficient computational algorithm for obtaining...... the equilibrium partition coefficient (pore-to-bulk concentration ratio) and the concentration profile inside the confining geometry. The algorithm involves two steps. First, certain characteristic structure properties of the studied macromolecule are obtained by sampling its configuration space, and second those...... data are used for the computation of partition coefficient and concentration profile for any confinement size. Our algorithm is versatile to the model and type of the macromolecule studied, and is capable of handling three types of confining geometries (slit, rectangular channel and rectangular box...

  6. The evaluation of the equilibrium partitioning method using sensitivity distributions of species in water and soil or sediment

    Beelen P van; Verbruggen EMJ; Peijnenburg WJGM; ECO


    The equilibrium partitioning method (EqP-method) can be used to derive environmental quality standards (like the Maximum Permissible Concentration or the intervention value) for soil or sediment, from aquatic toxicity data and a soil/water or sediment/water partitioning coefficient. The validity of

  7. Wave Reflection Coefficient Spectrum

    俞聿修; 邵利民; 柳淑学


    The wave reflection coefficient frequency spectrum and directional spectrum for concrete face slope breakwaters and rubble mound breakwaters are investigated through physical model tests in the present study. The reflection coefficients of oblique irregular waves are analyzed by the Modified Two-Point Method (MTPM) proposed by the authors. The results show that the wave reflection coefficient decreases with increasing wave frequency and incident angle or decreasing structure slope. The reflection coefficient frequency spectrum and its variation with Iribarren number are given in this paper. The paper also suggests an empirical 3-dimensional reflection coefficient spectrum, i.e. reflection coefficient directional spectrum, which can be used to illustrate quantitatively the variation of reflection coefficient with the incident angle and the Iribarren number for oblique irregular waves.

  8. The partition function of a ferromagnet up to three loops

    Hofmann, C P, E-mail: [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima, Colima 28045 (Mexico)


    The low-temperature behavior of ferromagnets with a spontaneously broken symmetry O(3) {yields} O(2) is analyzed within the perspective of effective Lagrangians. The leading coefficients of the low-temperature expansion for the partition function are calculated up to three loops and the manifestation of the spin-wave interaction in this series is discussed. The effective field theory method has the virtue of being completely systematic and model-independent.

  9. Amyloid Fibril Solubility

    Rizzi, L G


    It is well established that amyloid fibril solubility is protein specific, but how solubility depends on the interactions between the fibril building blocks is not clear. Here we use a simple protein model and perform Monte Carlo simulations to directly measure the solubility of amyloid fibrils as a function of the interaction between the fibril building blocks. Our simulations confirms that the fibril solubility depends on the fibril thickness and that the relationship between the interactions and the solubility can be described by a simple analytical formula. The results presented in this study reveal general rules how side-chain side-chain interactions, backbone hydrogen bonding and temperature affect amyloid fibril solubility, which might prove a powerful tool to design protein fibrils with desired solubility and aggregation properties in general.

  10. Partitioning of Sulfur and Platinum at Core Formation Conditions.

    Suer, T. A.; Siebert, J.; Fiquet, G.; Remusat, L.


    Measuring the partitioning behavior of highly siderophile elements (HSE) at high pressures and temperatures is important for understanding the mantle's elemental reservoir and the core mantle differentiation process. Low solubility of HSEs in silicate melts and the small size of samples obtained from diamond anvil cell (DAC) experiments have prevented the experimental study of the partitioning of these elements at realistic deep magma ocean conditions. In this study, we present results for metal-silicate partitioning experiments of sulfur and platinum conducted at pressures between 45 and 80 GPa and at temperatures from 3500 to 4200 K. With the nanoSIMS as our main tool for measuring trace element concentrations, we have developed a protocol for studying the partitioning behavior of these elements from samples that underwent equilibration at high pressure and temperatures in a Laser-Heated DAC. The nanoSIMS has the spatial resolution and the required sensitivity to measure the low concentration of some HSEs in the quenched silicate glass. The results of this study will help to refine current core-mantle differentiation models. Furthermore they add constraints to the contribution of the late veneer to the mantle's elemental abundances.

  11. [Water-Sediment Partition of Polycyclic Aromatic Hydrocarbons in Karst Underground River].

    Lan, Jia-cheng; Sun, Yu-chuan; Xiao, Shi-zhen


    Based on polycyclic aromatic hydrocarbons (PAHs) field data of dissolved phase and sediment phase, partition coefficient K(p) in sediment-water interface from Laolongdong underground river was obtained. The concentration of PAHs in water and sediment and partition coefficient K(p) in sediment-water interface were studied. The results showed PAHs concentrations were 81.5-8 089 ng x L(-1) with a mean value (1 439 ± 2 248) ng x L(-1) in water and 58.2-1 051 ng x g(-1) with an average (367.9 ± 342.6) ng x g(-1) in sediment. The dominant PAHs were 2-3 rings PAHs in water and sediment. However, high rings PAHs obviously enriched in the sediment. Partition coefficients varied from 55.74 to 46 067 L x kg(-1) in sediment-water interface, increasing with the rise of PAH compounds. All the organic carbon partition in sediment-water interface were higher than predicate values based on typical model of equilibrium distribution indicated that PAHs were strongly adsorbed in sediment. The linear free-energy relationship coefficient between K(oc) value and octanol-water partition coefficient K(ow) was 0.75, but the slope was lower than 1, indicating that sediment in Laolongdong underground river had weakly lipophilic characteristics and adsorption ability for PAHs.

  12. Jacobi-Stirling polynomials and $P$-partitions

    Gessel, Ira M; Zeng, Jiang


    We investigate the diagonal generating function of the Jacobi-Stirling numbers of the second kind $ \\JS(n+k,n;z)$ by generalizing the analogous results for the Stirling and Legendre-Stirling numbers. More precisely, letting $\\JS(n+k,n;z)=p_{k,0}(n)+p_{k,1}(n)z+...+p_{k,k}(n)z^k$, we show that $(1-t)^{3k-i+1}\\sum_{n\\geq0}p_{k,i}(n)t^n$ is a polynomial in $t$ with nonnegative integral coefficients and provide combinatorial interpretations of the coefficients by using Stanley's theory of $P$-partitions.

  13. The Partitioning of Tungsten bwtween Aqueous Fluids and Silicate Melts

    许永胜; 张本仁; 等


    An experimental study has been carried out to determine the partition coefficients of tungsten between aqueous fluids and granitic melts at 800℃ and 1.5kb with natural granite as the starting material,The effects of the solution on the partition coefficients of tungsten show a wequence of P>co32->B>H2O.The effects are limited(generally KD<0.3)and the tungsten shows a preferential trend toward the melt over the aqueous fiuid.The value of KD increases with increasing concentration of phosphorus;the KD increases first and then reduces with the concentration of CO32-;when temperature decreases,the KD between the solution of CO32- and the silicate melt increases,and that between the solution of B4O72- and the silicate melt decreases.The partition coefficients of phosphorus and sodium between fluids and silicate melts have been calculated from the concentrations of the elements in the melts.The KD value for phosphorus is 0.38 and that for sodium is 0.56.Evidence shows that the elements tend to become richer and richer in the melts.

  14. The influence of the surface composition of mixed monolayer films on the evaporation coefficient of water.

    Miles, Rachael E H; Davies, James F; Reid, Jonathan P


    We explore the dependence of the evaporation coefficient of water from aqueous droplets on the composition of a surface film, considering in particular the influence of monolayer mixed component films on the evaporative mass flux. Measurements with binary component films formed from long chain alcohols, specifically tridecanol (C13H27OH) and pentadecanol (C15H31OH), and tetradecanol (C14H29OH) and hexadecanol (C16H33OH), show that the evaporation coefficient is dependent on the mole fractions of the two components forming the monolayer film. Immediately at the point of film formation and commensurate reduction in droplet evaporation rate, the evaporation coefficient is equal to a mole fraction weighted average of the evaporation coefficients through the equivalent single component films. As a droplet continues to diminish in surface area with continued loss of water, the more-soluble, shorter alkyl chain component preferentially partitions into the droplet bulk with the evaporation coefficient tending towards that through a single component film formed simply from the less-soluble, longer chain alcohol. We also show that the addition of a long chain alcohol to an aqueous-sucrose droplet can facilitate control over the degree of dehydration achieved during evaporation. After undergoing rapid gas-phase diffusion limited water evaporation, binary aqueous-sucrose droplets show a continued slow evaporative flux that is limited by slow diffusional mass transport within the particle bulk due to the rapidly increasing particle viscosity and strong concentration gradients that are established. The addition of a long chain alcohol to the droplet is shown to slow the initial rate of water loss, leading to a droplet composition that remains more homogeneous for a longer period of time. When the sucrose concentration has achieved a sufficiently high value, and the diffusion constant of water has decreased accordingly so that bulk phase diffusion arrest occurs in the monolayer

  15. Efficient FM Algorithm for VLSI Circuit Partitioning



    Full Text Available In FM algorithm initial partitioning matrix of the given circuit is assigned randomly, as a result for larger circuit having hundred or more nodes will take long time to arrive at the final partition if theinitial partitioning matrix is close to the final partitioning then the computation time (iteration required is small . Here we have proposed novel approach to arrive at initial partitioning by using spectralfactorization method the results was verified using several circuits.

  16. Correlation analysis on partition of rare earth in ion-exchangeable phase from weathered crust ores

    CHI Ru-an; DAI Zu-xu; XU Zhi-gao; WU Yuan-xin; WANG Cun-wen


    The rare earth(RE) in weathered crust ores mainly exists as ion-exchangeable phase, approximately 80%. The correlation analysis on partition of 376 samples in ion-exchangeable phase from weathered crust ores was conducted. The results show that partition both among heavy RE elements and light RE elements with high partition appears positive correlation, but partition sums between the heavy RE elements and the light RE elements appear close negative correlation obviously. Clear negative correlations exist between the light RE elements (except Ce) and yttrium(Y). Matrix of correlation analysis on this partition can be divided into three zones. The correlated coefficient variation from negative to positive in zones B and C occurs at Gd, so does that in zones B and A (except Ce, Eu, and Sm), suggesting that RE elements can be divided into two groups with Gd as border. This phenomenon is called Gadolinium-broken effect.

  17. Three phase partitioning leads to subtle structural changes in proteins.

    Rather, Gulam Mohmad; Gupta, Munishwar Nath


    Three phase partitioning consists of precipitation of proteins due to simultaneous presence of ammonium sulphate and t-butanol. The technique has been successfully used for purification and refolding of proteins. There are however indications that the structures of proteins subjected to three phase partitioning are different from native structure of proteins. Taking several proteins, the present work examines the structural changes in proteins by comparing their thermal stabilities, secondary structure contents, surface hydrophobicities, hydrodynamic radii and solubilities in the presence of ammonium sulphate. The results show that while the nature or extent of structural changes may vary, in all the cases the changes are rather subtle and not drastic in nature. Hence, the technique can be safely used for protein purification and refolding.

  18. Thermometry of the magma ocean: Controls on the metal-silicate partitioning of gold

    Bennett, N. R.; Brenan, J. M.; Fei, Y.


    We have performed experiments to investigate the solubility and metal-silicate partitioning of gold as a function of metal sulphur content (XS), silicate melt polymerization (NBO/T) and pressure (P). These experiments show that Au becomes less siderophile both with increasing pressure and as the metal phase becomes more sulphur-rich. For the studied range of compositions, melt polymerization has no effect on the solubility of Au. The reduction in the siderophile tendency of gold with increasing metal sulphur content is greater than expected on the basis of activity-composition relationships in the metal phase. This suggests a significant role for complexing between Au and S in the silicate melt. Our new experimental results are combined with literature data to yield a parameterisation for the exchange coefficient of Au (KdAuMet/Sil) as a function of P, T and XS: Using this relationship, alongside similar parameterisations for Ni and Co selected from the literature, we performed continuous accretion models to delineate regions of parameter space in which Au and moderately siderophile element (MSE) abundances in the primitive upper mantle (PUM) could be reproduced. These models suggest that for metal-silicate equilibrium at very high pressures, Au will be overabundant in the PUM if equilibrium also occurs at extreme temperatures. Instead, most successful models are found when equilibrium occurs at high pressure but sub-liquidus temperatures. This result is in keeping with the physical conditions expected for a scenario where core-forming metal ponds and equilibrates at the rheological base of a magma ocean (e.g. Wade and Wood, 2005).

  19. Solubility of guaifenesin in the presence of common pharmaceutical additives.

    Mani, Narasimhan; Jun, H W; Beach, J Warren; Nerurkar, Jayanti


    The aqueous solubility of guaifenesin, a highly water-soluble drug, in the presence of salts, sugars, and cosolvents was determined at 25 degrees C and 40 degrees C. The solubility of drug at both temperatures was reduced with increasing concentrations of salts and sugars. The extent of reduction in drug solubility was dependent on the type of salts and sugars used. The salting-out coefficient of additives was calculated by plotting log-linear solubility profiles of the drug against the concentrations of the additives. The solubility of guaifenesin, a neutral compound, was found to be higher at lower pH values, which could be due to hydrogen-bonding effects. At 25 degrees C, glycerin, PEG 300, and propylene glycol increased the solubility of drug at low solvent concentrations while the solubility was reduced at high concentrations. At 40 degrees C, the solubility of drug was reduced at all concentrations of cosolvents. The thermodynamic events accompanying the solubility process were discussed to explain the solubility phenomena observed in the presence of additives. The reduced aqueous solubility of guaifenesin in the presence of additives greatly improved the entrapment of drug into controlled-release wax microspheres.

  20. Classification algorithms using adaptive partitioning

    Binev, Peter


    © 2014 Institute of Mathematical Statistics. Algorithms for binary classification based on adaptive tree partitioning are formulated and analyzed for both their risk performance and their friendliness to numerical implementation. The algorithms can be viewed as generating a set approximation to the Bayes set and thus fall into the general category of set estimators. In contrast with the most studied tree-based algorithms, which utilize piecewise constant approximation on the generated partition [IEEE Trans. Inform. Theory 52 (2006) 1335.1353; Mach. Learn. 66 (2007) 209.242], we consider decorated trees, which allow us to derive higher order methods. Convergence rates for these methods are derived in terms the parameter - of margin conditions and a rate s of best approximation of the Bayes set by decorated adaptive partitions. They can also be expressed in terms of the Besov smoothness β of the regression function that governs its approximability by piecewise polynomials on adaptive partition. The execution of the algorithms does not require knowledge of the smoothness or margin conditions. Besov smoothness conditions are weaker than the commonly used Holder conditions, which govern approximation by nonadaptive partitions, and therefore for a given regression function can result in a higher rate of convergence. This in turn mitigates the compatibility conflict between smoothness and margin parameters.

  1. Correlations for the partition behavior of proteins in aqueous two-phase systems

    Schmidt, A.S.; Andrews, B.A.; Asenjo, J.A.


    of the overall protein concentration, by the ratio between the ''saturation'' equations of the two individual phases. Better correlations were obtained when an empirical sigmoidal Boltzmann equation was fitted to the data, since in virtually all cases the partition coefficient is constant at low protein...... concentration (true partitioning) and changes to a different constant value at a high overall protein concentration. (C) 1996 John Wiley & Sons, Inc....

  2. Soluble oil cutting fluid

    Rawlinson, A.P.; White, J.


    A soluble oil, suitable when diluted with water, for use as a cutting fluid comprises an alkali or alkaline-earth metal alkyl benzene sulphonate, a fatty acid diethanolamide, a mixed alkanolamine borate, a polyisobutenesuccinimide and a major proportion of mineral oil. The soluble oil is relatively stable without the need for a conventional coupling agent and some soluble oil emulsions are bio-static even though conventional biocides are not included.

  3. Gentile statistics and restricted partitions

    C S Srivatsan; M V N Murthy; R K Bhaduri


    In a recent paper (Tran et al, Ann. Phys. 311, 204 (2004)), some asymptotic number theoretical results on the partitioning of an integer were derived exploiting its connection to the quantum density of states of a many-particle system. We generalise these results to obtain an asymptotic formula for the restricted or coloured partitions $p_{k}^{s} (n)$, which is the number of partitions of an integer into the summand of th powers of integers such that each power of a given integer may occur utmost times. While the method is not rigorous, it reproduces the well-known asymptotic results for = 1 apart from yielding more general results for arbitrary values of .

  4. Extremal sizes of subspace partitions

    Heden, Olof; Nastase, Esmeralda; Sissokho, Papa


    A subspace partition $\\Pi$ of $V=V(n,q)$ is a collection of subspaces of $V$ such that each 1-dimensional subspace of $V$ is in exactly one subspace of $\\Pi$. The size of $\\Pi$ is the number of its subspaces. Let $\\sigma_q(n,t)$ denote the minimum size of a subspace partition of $V$ in which the largest subspace has dimension $t$, and let $\\rho_q(n,t)$ denote the maximum size of a subspace partition of $V$ in which the smallest subspace has dimension $t$. In this paper, we determine the values of $\\sigma_q(n,t)$ and $\\rho_q(n,t)$ for all positive integers $n$ and $t$. Furthermore, we prove that if $n\\geq 2t$, then the minimum size of a maximal partial $t$-spread in $V(n+t-1,q)$ is $\\sigma_q(n,t)$.

  5. Modeling of diffusion with partitioning in stratum corneum using a finite element model.

    Barbero, Ana M; Frasch, H F


    Partitioning and diffusion of chemicals in skin is of interest to researchers in areas such as transdermal penetration and drug disposition, either for risk assessment or transdermal delivery. In this study a finite element method is used to model diffusion in the skin's outermost layer, the stratum corneum (SC). The SC is considered to be a finite two-dimensional composite having different diffusivity values in each medium as well as a partition coefficient at the interfaces between media. A commercial finite element package with thermal analysis capabilities is selected due to the flexibility of this software to handle irregular geometries. Partitioning is accommodated through a change of variables technique. This technique is validated by comparison of model results with analytical solutions of steady-state flux, transient concentration profiles, and time lag for diffusion in laminates. Two applications are presented. Diffusion is solved in a two-dimensional "brick and mortar" geometry that is a simplification of human stratum corneum, with a partition coefficient between corneocyte and lipid. Results are compared to the diffusion in multiple laminates to examine effects of the partition coefficient. The second application is the modeling of diffusion with partitioning through an irregular geometry which is obtained from a micrograph of hairless mouse stratum corneum.

  6. Solubilities of krypton and xenon in dichlorodifluoromethane

    Shaffer, J.H.; Shockley, W.E.; Greene, C.W.


    The solubility behavior of krypton and xenon in dichlorodifluoromethane was investigated for the Consolidated Fuel Reprocessing Program (CFRP) in support of the fluorocarbon absorption process. The solubility data derived from solute radioisotopes had uncertainties of approx. 0.1%. Values for Henry's law constants were initially determined under equilibrium conditions at infinite solute dilution. Based on these results, the study was extended to finite solute concentrations. Nonidealities in the two binary systems were expressed as gas phase fugacity coefficients for each solute at 10/sup 0/ intervals over the range -30 to +50/sup 0/C. 22 references, 4 figures, 2 tables.

  7. Modeling of Salt Solubilities in Mixed Solvents

    Chiavone-Filho, O.; Rasmussen, Peter


    A method to correlate and predict salt solubilities in mixed solvents using a UNIQUAC+Debye-Huckel model is developed. The UNIQUAC equation is applied in a form with temperature-dependent parameters. The Debye-Huckel model is extended to mixed solvents by properly evaluating the dielectric...... constants and the liquid densities of the solvent media. To normalize the activity coefficients, the symmetric convention is adopted. Thermochemical properties of the salt are used to estimate the solubility product. It is shown that the proposed procedure can describe with good accuracy a series of salt...

  8. Modeling of Salt Solubilities in Mixed Solvents

    Chiavone-Filho, O.; Rasmussen, Peter


    A method to correlate and predict salt solubilities in mixed solvents using a UNIQUAC+Debye-Huckel model is developed. The UNIQUAC equation is applied in a form with temperature-dependent parameters. The Debye-Huckel model is extended to mixed solvents by properly evaluating the dielectric...... constants and the liquid densities of the solvent media. To normalize the activity coefficients, the symmetric convention is adopted. Thermochemical properties of the salt are used to estimate the solubility product. It is shown that the proposed procedure can describe with good accuracy a series of salt...

  9. Method for Predicting Solubilities of Solids in Mixed Solvents

    Ellegaard, Martin Dela; Abildskov, Jens; O'Connell, J. P.


    A method is presented for predicting solubilities of solid solutes in mixed solvents, based on excess Henry's law constants. The basis is statistical mechanical fluctuation solution theory for composition derivatives of solute/solvent infinite dilution activity coefficients. Suitable approximations...... are made for a single parameter characterizing solute/solvent interactions. Comparisons with available data show that the method is successful in describing a variety of observed mixed solvent solubility behavior, including nearly ideal systems with small excess solubilities, systems with solute......-independent excess solubilities, and systems deviating from these simple rules. Successful predictions for new solvent mixtures cat? be made using limited data from other mixtures....

  10. Designing lipids for selective partitioning into liquid ordered membrane domains.

    Momin, Noor; Lee, Stacey; Gadok, Avinash K; Busch, David J; Bachand, George D; Hayden, Carl C; Stachowiak, Jeanne C; Sasaki, Darryl Y


    Self-organization of lipid molecules into specific membrane phases is key to the development of hierarchical molecular assemblies that mimic cellular structures. While the packing interaction of the lipid tails should provide the major driving force to direct lipid partitioning to ordered or disordered membrane domains, numerous examples show that the headgroup and spacer play important but undefined roles. We report here the development of several new biotinylated lipids that examine the role of spacer chemistry and structure on membrane phase partitioning. The new lipids were prepared with varying lengths of low molecular weight polyethylene glycol (EGn) spacers to examine how spacer hydrophilicity and length influence their partitioning behavior following binding with FITC-labeled streptavidin in liquid ordered (Lo) and liquid disordered (Ld) phase coexisting membranes. Partitioning coefficients (Kp Lo/Ld) of the biotinylated lipids were determined using fluorescence measurements in studies with giant unilamellar vesicles (GUVs). Compared against DPPE-biotin, DPPE-cap-biotin, and DSPE-PEG2000-biotin lipids, the new dipalmityl-EGn-biotin lipids exhibited markedly enhanced partitioning into liquid ordered domains, achieving Kp of up to 7.3 with a decaethylene glycol spacer (DP-EG10-biotin). We further demonstrated biological relevance of the lipids with selective partitioning to lipid raft-like domains observed in giant plasma membrane vesicles (GPMVs) derived from mammalian cells. Our results found that the spacer group not only plays a pivotal role for designing lipids with phase selectivity but may also influence the structural order of the domain assemblies.

  11. The Partition Ensemble Fallacy Fallacy

    Nemoto, K; Nemoto, Kae; Braunstein, Samuel L.


    The Partition Ensemble Fallacy was recently applied to claim no quantum coherence exists in coherent states produced by lasers. We show that this claim relies on an untestable belief of a particular prior distribution of absolute phase. One's choice for the prior distribution for an unobservable quantity is a matter of `religion'. We call this principle the Partition Ensemble Fallacy Fallacy. Further, we show an alternative approach to construct a relative-quantity Hilbert subspace where unobservability of certain quantities is guaranteed by global conservation laws. This approach is applied to coherent states and constructs an approximate relative-phase Hilbert subspace.

  12. Partitions of generalized split graphs

    Shklarsky, Oren


    We discuss matrix partition problems for graphs that admit a partition into k independent sets and ` cliques. We show that when k + ` 6 2, any matrix M has finitely many (k; `) minimal obstructions and hence all of these problems are polynomial time solvable. We provide upper bounds for the size of any (k; `) minimal obstruction when k = ` = 1 (split graphs), when k = 2; ` = 0 (bipartite graphs), and when k = 0; ` = 2 (co-bipartite graphs). When k = ` = 1, we construct an exponential size spl...

  13. The complexity of string partitioning

    Condon, Anne; Thachuk, Chris


    Given a string $w$ over a finite alphabet $\\Sigma$ and an integer $K$, can $w$ be partitioned into strings of length at most $K$, such that there are no \\emph{collisions}? We refer to this question as the \\emph{string partition} problem and show it is \\NP-complete for various definitions of collision and for a number of interesting restrictions including $|\\Sigma|=2$. This establishes the hardness of an important problem in contemporary synthetic biology, namely, oligo design for gene synthesis.

  14. Homomorphic Hashing for Sparse Coefficient Extraction

    Kaski, Petteri; Nederlof, Jesper


    We study classes of Dynamic Programming (DP) algorithms which, due to their algebraic definitions, are closely related to coefficient extraction methods. DP algorithms can easily be modified to exploit sparseness in the DP table through memorization. Coefficient extraction techniques on the other hand are both space-efficient and parallelisable, but no tools have been available to exploit sparseness. We investigate the systematic use of homomorphic hash functions to combine the best of these methods and obtain improved space-efficient algorithms for problems including LINEAR SAT, SET PARTITION, and SUBSET SUM. Our algorithms run in time proportional to the number of nonzero entries of the last segment of the DP table, which presents a strict improvement over sparse DP. The last property also gives an improved algorithm for CNF SAT with sparse projections.

  15. An Efficient and Scalable Image Codec Based on Binary Set Partitioning

    CHENJunhua; ZHANGWenjun; ZHANGZhenghua


    An image codec based on binary set partitioning is presented, where the discrete wavelet transformed coefficients are represented by zeroblocks instead of the conventional zerotrees. Binary trees are built before coding whose nodes are associated with blocks (sets) of coefficients from individual subbands. The significant blocksare partitioned in a binary tree splitting way to locate significant coefficients. Even without utilizing arithmetic coding which is time-consuming and sensitive to errors, the scheme achieves high coding efficiency due to the effective set partitioning algorithm. All subbands are coded independently in bitplanes, resulting in spatial and rate scalability. With the assistance of the list facility, the algorithm can be implemented very fast. Experimental results show that the proposed scheme outperforms the SPIHT in binary mode and gets similar coding efficiency to the SPIHT utilizing arithmetic coding, especially in very low bitrate.

  16. Modified Biserial Correlation Coefficients.

    Kraemer, Helena Chmura


    Asymptotic distribution theory of Brogden's form of biserial correlation coefficient is derived and large sample estimates of its standard error obtained. Its relative efficiency to the biserial correlation coefficient is examined. Recommendations for choice of estimator of biserial correlation are presented. (Author/JKS)

  17. Determination of apparent oil-water partition coefficient and equilibrium solubility of levonorgestrel and gestodene by RP-HPLC%RP-HPLC测定左炔诺孕酮与孕二烯酮表观油水分配系数及平衡溶解度

    曾佳; 黄婷; 李芳; 朱芷涵; 陈良康; 俸灵林


    目的:分别测定第2代和第3代避孕药代表性药物左炔诺孕酮(levonorgestrel,LNG)与孕二烯酮(gestodene,GES)的表观油水分配系数及平衡溶解度,为长效避孕微球注射剂制备工艺及体外释放介质的选择提供坚实的处方前研究基础.方法:采用RP-HPLC测定LNG与GES在正辛醇-水、正辛醇-pH 1.2~8.0磷酸盐缓冲液等9种体系中的表观油水分配系数及在水、缓冲液、常用有机溶剂等19种介质中的平衡溶解度.结果:LNG与GES在水中的lgPapp值分别为3.62和3.43;在不同pH值PBS中该值相近,但在pH3.0时例外,LNG与GES的该值均增大.此外,两药均难溶于水,易溶于二氯甲烷、三氯甲烷等有机溶剂;GES的水溶性是LNG的8~ 10倍,且GES比LNG更易溶于有机试剂;两者在pH 3.0时溶解度均有下降趋势,而在其他pH值条件下无明显差别,该情况与两者表观油水分配系数的变化规律相一致.结论:表观油水分配系数结果提示:LNG与GES在微球制备过程中可获得较好的包封率,同时将延长微球在体内的释药周期.平衡溶解度结果提示:在微球体外释放评价时应添加合适的增溶剂以增加药物溶解度来满足漏槽条件;制备微球采用常规工艺的水包油(O/W)型乳剂-液中干燥法微囊化具有可行性.

  18. Chemical composition analysis of the essential oil of Melissa officinalis L. from Kurdistan, Iran by HS/SPME method and calculation of the biophysicochemical coefficients of the components.

    Taherpour, Avat Arman; Maroofi, Hossein; Rafie, Zeinab; Larijani, Kambiz


    The volatile constituents of the essential oil of wild Melissa officinalis L. obtained from the Kurdistan province of Iran were extracted by headspace/solid-phase micro-extraction and were analysed by gas chromatography and gas chromatography/mass spectrometry. Of a total of 14 compounds in the oil, 12 (85.7%) were identified. The main components were as follows: (E)-citral (37.2%), neral (23.9%) and citronellal (20.3%). Some physicochemical properties, such as the logarithm of calculated octanol-water partitioning coefficients (log K (ow))(,) total biodegradation (TB (d) in mol h(-1) and g h(-1)), water solubility (S (w), mg L(-1) at 25°C) and median lethal concentration 50 (LC(50)), were calculated for compounds 1-14 from M. officinalis L.

  19. Hildebrand solubility parameter to predict drug release from hydroxypropyl methylcellulose gels.

    Bustamante, P; Navarro-Lupión, J; Peña, M A; Escalera, B


    An equation including the Hildebrand solubility parameter δ of the drugs is used for the first time to model drug release from hydroxypropyl methylcellulose (HPMC) gels: l nM = -21.578 + 2.102 δ-0.037 δ(2)+0.48 ln t + 1.028 ln C(i) (r(2) = 0.94 for a total of 286 cases). The experimentally determined release data of six drugs having different polarity (caffeine, theophylline, paracetamol, salicylic acid, naproxen and diclofenac) at several initial concentrations C(i) were included in the equation. In general, the amount of drug delivered is linear at the first 5-6h of the release profiles and the zero order constants K(o) increase as the solubility parameter of the drugs become larger. The Peppas exponential law M/M(∞) = Kt(n) is applicable to larger fractional release, until 67-87% (48-51 h) for the less polar drugs (diclofenac and naproxen, lower δ values) and more than 80% (26-28 h) for the more polar drugs (higher δ values, theophylline, salicylic acid, caffeine and paracetamol). The Peppas release rate (lnK) shows a parabolic relationship with the drug solubility parameter. The diffusional exponent n varies between 0.40 and 0.58 indicating that drug release is mainly controlled by diffusion. An extended form of the Peppas equation is also tested for each drug including all the initial concentrations: lnM = a + b ln t + c ln C(i) (r(2) = 0.88-0.94). The logarithm of the octanol-water partition coefficients can also be used in combination with the drug concentrations. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Extended Hansen solubility approach: naphthalene in individual solvents.

    Martin, A; Wu, P L; Adjei, A; Beerbower, A; Prausnitz, J M


    A multiple regression method using Hansen partial solubility parameters, delta D, delta p, and delta H, was used to reproduce the solubilities of naphthalene in pure polar and nonpolar solvents and to predict its solubility in untested solvents. The method, called the extended Hansen approach, was compared with the extended Hildebrand solubility approach and the universal-functional-group-activity-coefficient (UNIFAC) method. The Hildebrand regular solution theory was also used to calculate naphthalene solubility. Naphthalene, an aromatic molecule having no side chains or functional groups, is "well-behaved', i.e., its solubility in active solvents known to interact with drug molecules is fairly regular. Because of its simplicity, naphthalene is a suitable solute with which to initiate the difficult study of solubility phenomena. The three methods tested (Hildebrand regular solution theory was introduced only for comparison of solubilities in regular solution) yielded similar results, reproducing naphthalene solubilities within approximately 30% of literature values. In some cases, however, the error was considerably greater. The UNIFAC calculation is superior in that it requires only the solute's heat of fusion, the melting point, and a knowledge of chemical structures of solute and solvent. The extended Hansen and extended Hildebrand methods need experimental solubility data on which to carry out regression analysis. The extended Hansen approach was the method of second choice because of its adaptability to solutes and solvents from various classes. Sample calculations are included to illustrate methods of predicting solubilities in untested solvents at various temperatures. The UNIFAC method was successful in this regard.

  1. The Solubility of struvite

    Aage, H. K.; Andersen, Bertel Lohmann; Blom, A.


    The solubility of magnesium-amonium-phosphate (struvite) has been studied emloying the radioisotope 32P as tracer. The amount of sample in solution is determined by measuring the Cherenkov radiation due to the beta-particles emitted from this radionuclide. The thermodynamic solubility product...

  2. Assimilate Partitioning and Plant Development

    Yong-Ling Ruan; John W.Patrick; Hans Weber


    @@ It has been a pleasure to organize this special issue of Molecular Plant on 'Assimilate Partitioning and Plant Development'. Assimilate, a collective term describing organic carbon (C) and nitrogen (N), is of paramount importance for plant development and realization of crop productivity.

  3. Gershgorin domains for partitioned matrices

    Sluis, A. van der


    Inclusion domains for the eigenvalues of a partitioned matrix are specified in terms of perturbations of its diagonal blocks. The size of such perturbations is measured using the Kantorovitch-Robert-Deutsch vectorial norms. The inclusion domains obtained thereby are compared with inclusion domains o

  4. Unsupervised segmentation of MRI knees using image partition forests

    Marčan, Marija; Voiculescu, Irina


    Nowadays many people are affected by arthritis, a condition of the joints with limited prevention measures, but with various options of treatment the most radical of which is surgical. In order for surgery to be successful, it can make use of careful analysis of patient-based models generated from medical images, usually by manual segmentation. In this work we show how to automate the segmentation of a crucial and complex joint -- the knee. To achieve this goal we rely on our novel way of representing a 3D voxel volume as a hierarchical structure of partitions which we have named Image Partition Forest (IPF). The IPF contains several partition layers of increasing coarseness, with partitions nested across layers in the form of adjacency graphs. On the basis of a set of properties (size, mean intensity, coordinates) of each node in the IPF we classify nodes into different features. Values indicating whether or not any particular node belongs to the femur or tibia are assigned through node filtering and node-based region growing. So far we have evaluated our method on 15 MRI knee images. Our unsupervised segmentation compared against a hand-segmented gold standard has achieved an average Dice similarity coefficient of 0.95 for femur and 0.93 for tibia, and an average symmetric surface distance of 0.98 mm for femur and 0.73 mm for tibia. The paper also discusses ways to introduce stricter morphological and spatial conditioning in the bone labelling process.

  5. Partitioning of phthalates among the gas phase, airborne particles and settled dust in indoor environments

    Weschler, Charles J.; Salthammer, Tunga; Fromme, Hermann


    . The particle concentration, C-particle, of a given phthalate was calculated from its total airborne concentration and the concentration of airborne particles (PM4). This required knowledge of the particle-gas partition coefficient, K., which was estimated from either the saturation vapor pressure (p......(s)) or the octanol/air partition coefficient (K-OA). For each phthalate in each apartment, the ratio of its particle concentration to its dust concentration (C-particle/C-Dust) was calculated, The median values of this ratio were within an order of magnitude of one another for five of the phthalate esters despite...

  6. Transport Coefficients of Fluids

    Eu, Byung Chan


    Until recently the formal statistical mechanical approach offered no practicable method for computing the transport coefficients of liquids, and so most practitioners had to resort to empirical fitting formulas. This has now changed, as demonstrated in this innovative monograph. The author presents and applies new methods based on statistical mechanics for calculating the transport coefficients of simple and complex liquids over wide ranges of density and temperature. These molecular theories enable the transport coefficients to be calculated in terms of equilibrium thermodynamic properties, and the results are shown to account satisfactorily for experimental observations, including even the non-Newtonian behavior of fluids far from equilibrium.

  7. Optimized Local Trigonometric Bases with Nonuniform Partitions

    Qiao Fang LIAN; Yong Ge WANG; Dun Yan YAN


    The authors provide optimized local trigonometric bases with nonuniform partitions which efficiently compress trigonometric functions. Numerical examples demonstrate that in many cases the proposed bases provide better compression than the optimized bases with uniform partitions obtained by Matviyenko.

  8. Partitioning of selected antioxidants in mayonnaise

    Jacobsen, Charlotte; Schwarz, K.; Stockmann, H.


    This study examined partitioning of alpha-, beta-, and gamma- tocopherol and six polar antioxidants (Trolox, ferulic acid, caffeic acid, propyl gallate, gallic acid, and catechin) in mayonnaise. Partitioning of antioxidants between different phases was determined after separation of mayonnaise by...

  9. On free fermions and plane partitions

    Foda, O; Zuparic, M


    We use free fermion methods to re-derive a result of Okounkov and Reshetikhin relating charged fermions to random plane partitions, and to extend it to relate neutral fermions to strict plane partitions.

  10. Bitplane Image Coding With Parallel Coefficient Processing.

    Auli-Llinas, Francesc; Enfedaque, Pablo; Moure, Juan C; Sanchez, Victor


    Image coding systems have been traditionally tailored for multiple instruction, multiple data (MIMD) computing. In general, they partition the (transformed) image in codeblocks that can be coded in the cores of MIMD-based processors. Each core executes a sequential flow of instructions to process the coefficients in the codeblock, independently and asynchronously from the others cores. Bitplane coding is a common strategy to code such data. Most of its mechanisms require sequential processing of the coefficients. The last years have seen the upraising of processing accelerators with enhanced computational performance and power efficiency whose architecture is mainly based on the single instruction, multiple data (SIMD) principle. SIMD computing refers to the execution of the same instruction to multiple data in a lockstep synchronous way. Unfortunately, current bitplane coding strategies cannot fully profit from such processors due to inherently sequential coding task. This paper presents bitplane image coding with parallel coefficient (BPC-PaCo) processing, a coding method that can process many coefficients within a codeblock in parallel and synchronously. To this end, the scanning order, the context formation, the probability model, and the arithmetic coder of the coding engine have been re-formulated. The experimental results suggest that the penalization in coding performance of BPC-PaCo with respect to the traditional strategies is almost negligible.

  11. Effects of Sequence Partitioning on Compression Rate

    Alagoz, B Baykant


    In the paper, a theoretical work is done for investigating effects of splitting data sequence into packs of data set. We proved that a partitioning of data sequence is possible to find such that the entropy rate at each subsequence is lower than entropy rate of the source. Effects of sequence partitioning on overall compression rate are argued on the bases of partitioning statistics, and then, an optimization problem for an optimal partition is defined to improve overall compression rate of a sequence.

  12. Vapor-liquid partitioning of alkaline earth and transition metals in NaCl-dominated hydrothermal fluids: An experimental study from 360 to 465 °C, near-critical to halite saturated conditions

    Pester, Nicholas J.; Ding, Kang; Seyfried, William E.


    Multi-phase fluid flow is a common occurrence in magmatic hydrothermal systems; and extensive modeling efforts using currently established P-V-T-x properties of the NaCl-H2O system are impending. We have therefore performed hydrothermal flow experiments (360-465 °C) to observe vapor-liquid partitioning of alkaline earth and first row transition metals in NaCl-dominated source solutions. The data allow extraction of partition coefficients related to the intrinsic changes in both chlorinity and density along the two-phase solvus. The coefficients yield an overall decrease in vapor affinity in the order Cu(I) > Na > Fe(II) > Zn > Ni(II) ⩾ Mg ⩾ Mn(II) > Co(II) > Ca > Sr > Ba, distinguished with 95% confidence for vapor densities greater than ∼0.2 g/cm3. The alkaline earth metals are limited to purely electrostatic interactions with Cl ligands, resulting in an excellent linear correlation (R2 > 0.99) between their partition coefficients and respective ionic radii. Though broadly consistent with this relationship, relative behavior of the transition metals is not well resolved, being likely obscured by complex bonding processes and the potential participation of Na in the formation of tetra-chloro species. At lower densities (at/near halite saturation) partitioning behavior of all metals becomes highly non-linear, where M/Cl ratios in the vapor begin to increase despite continued decreases in chlorinity and density. We refer to this phenomenon as "volatility", which is broadly associated with substantial increases in the HCl/NaCl ratio (eventually to >1) due to hydrolysis of NaCl. Some transition metals (e.g., Fe, Zn) exhibit volatility prior to halite stability, suggesting a potential shift in vapor speciation relative to nearer critical regions of the vapor-liquid solvus. The chemistry of deep-sea hydrothermal fluids appears affected by this process during magmatic events, however, our results do not support suggestions of subseafloor halite precipitation

  13. Octanol-solubility of dissolved and particulate trace metals in contaminated rivers: implications for metal reactivity and availability.

    Turner, Andrew; Mawji, Edward


    The lipid-like, amphiphilic solvent, n-octanol, has been used to determine a hydrophobic fraction of dissolved and particulate trace metals (Al, Cd, Co, Cu, Mn, Ni, Pb, Zn) in contaminated rivers. In a sample from the River Clyde, southwest Scotland, octanol-solubility was detected for all dissolved metals except Co, with conditional octanol-water partition coefficients, D(ow), ranging from about 0.2 (Al and Cu) to 1.25 (Pb). In a sample taken from the River Mersey, northwest England, octanol-solubility was detected for dissolved Al and Pb, but only after sample aliquots had been spiked with individual ionic metal standards and equilibrated. Spiking of the River Clyde sample revealed competition among different metals for hydrophobic ligands. Metal displacement from hydrophobic complexes was generally most significant following the addition of ionic Al or Pb, although the addition of either of these metals had little effect on the octanol-solubility of the other. In both river water samples hydrophobic metals were detected on the suspended particles retained by filtration following their extraction in n-octanol. In general, particulate Cu and Zn (up to 40%) were most available, and Al, Co and Pb most resistant (metal to octanol-soluble dissolved metal were in the range 10(3.3)-10(5.3)mlg(-1). The presence of hydrophobic dissolved and particulate metal species has implications for our understanding of the biogeochemical behaviour of metals in aquatic environments. Specifically, such species are predicted to exhibit characteristics of non-polar organic contaminants, including the potential to penetrate the lipid bilayer. Current strategies for assessing the bioavailability and toxicity of dissolved and particulate trace metals in natural waters may, therefore, require revision.

  14. Solving set partitioning problems using lagrangian relaxation

    van Krieken, M.G.C.


    This thesis focuses on the set partitioning problem. Given a collection of subsets of a certain root set and costs associated to these subsets, the set partitioning problem is the problem of finding a minimum cost partition of the root set. Many real-life problems, such as vehicle routing and crew s

  15. Anhydrite solubility in differentiated arc magmas

    Masotta, M.; Keppler, H.


    The solubility of anhydrite in differentiated arc magmas was experimentally studied at 200 MPa and 800-1000 °C over a range of oxygen fugacities, from 0.5 log units above the Ni-NiO buffer to the hematite-magnetite buffer. Anhydrite is stable only at oxidizing conditions (fO2 ⩾ Re-ReO2), whereas sulfides only form under reducing conditions. The solubility of anhydrite in the melt ultimately regulates the amount of sulfur available to partition between melt and fluid phase during the eruption. At oxidizing conditions, the solubility product of anhydrite increases with temperature, nbo/t and melt water content. We provide a new calibration of the anhydrite solubility product (KSP = XCaO * XSO3), which reproduces all available experimental data with greatly improved accuracy: In this equation, the molar fractions XCaO and XSO3 in the melt as well as the number of non-bridging oxygen atoms per tetrahedron (nbo/t) are calculated on an anhydrous basis (H2O refers to the melt water content, T is temperature in Kelvin). We apply our model to estimate the sulfur yield of some recent volcanic eruptions and we show that the sulfur yield of the 1991 Mt. Pinatubo dacite eruption was unusually large, because only a small fraction of the sulfur was locked up in anhydrite. In general, high sulfur yields are expected when anhydrite solubility in the melt is high, i.e. for somewhat depolymerized melts. For rhyolitic systems, most of the available sulfur will be locked up in anhydrite, so that even very large eruptions may only have a small effect on global surface temperatures. Our model therefore allows improved predictions of the environmental impact of explosive volcanic eruptions.

  16. Numerical solution for 5-layer laminate technique to determine saturation solubility of a drug in a thin film of pressure sensitive adhesive.

    Bänsch, Eberhard; Reismann, Simone; Lee, Geoffrey


    A numerical solution of the one-dimensional diffusion equation is presented to describe the 5-layer laminate technique for estimating the saturation solubility of a drug in a thin polymer film. The boundary and initial conditions encompass a donor layer, a separating membrane, and an acceptor layer. Alteration of the drug's partition coefficient between donor and separating membrane has little influence on drug accumulation with the acceptor. The diffusivity in the separating membrane should be high to promote a short experimental time to achieve saturation equilibrium in the acceptor layer. The essential parameter to give rapid equilibrium is the thickness of the acceptor polymer film. For values of diffusivity typical for drugs of molecular weight around 500 an acceptor layer thickness of 10 µm-20 µm is required to achieve equilibrium within less than 10 d. These simulations allow the selection of suitable experimental conditions to make the 5-layer laminate technique a viable method for routine use.

  17. Existing State and Partitioning of Rare Earth on Weathered Ores


    The existing state and partitioning of rare earth (RE) on weathered ores in Longnan County (LN), Xingfeng County(XF) and Ninghua County(NH) were characterized systematically by standard geological analytical methods. It is found that RE in the weathered rare earth ores exist as four phases: (a) water soluble, (b) ion-exchangeable, (c) colloidal sediment (oxides), (d) minerals, in which mainly as ion exchangeable phase, accounting for nearly 80% of total RE,with about 20% in the form of colloid sediment phase and mineral phase, but very little as aqueous soluble phase. These rare earth partitioning were mainly chosen mid-heavy RE elements, occupying above 60%, but not equal in the four phases. The mid-heavy RE elements were primarily enriched in the ion exchangeable phase up to 40%, while the containment of cerium dioxide is below 2%. The cerium deficiency occurs in the ion exchangeable phase in weathered ore. It results from that the Ce3+ is oxidized into Ce4+ and changes into CeO2. For LN ore, the containment of Y is high in weathered ore because Y-minerals are abundant in original rock.

  18. The partitioning of Cu, Au and Mo between liquid and vapor at magmatic temperatures and its implications for the genesis of magmatic-hydrothermal ore deposits

    Zajacz, Zoltán; Candela, Philip A.; Piccoli, Philip M.


    The partition coefficients of Cu, Au and Mo between liquid and vapor were determined at P = 130 MPa and T = 900 °C, and P = 90 MPa and T = 650 °C and redox conditions favoring the dominance of reduced S species in the fluid. The experiments at 900 °C were conducted in rapid-quench Molybdenum-Hafnium Carbide externally-heated pressure vessel assemblies, whereas those at 650 °C were run in René41 pressure vessels. The fluids were sampled at run conditions using the synthetic fluid inclusion technique. The host quartz was fractured in situ during the experiments ensuring the entrapment of equilibrium fluids. A new method was developed to quantify the composition of the vapor inclusions from LA-ICPMS analyses relying on the use of boron as an internal standard, an element that fractionates between vapor and liquid to a very small degree. The bulk starting fluid compositions closely represented those expected to exsolve from felsic silicate melts in upper crustal magma reservoirs (0.64 m NaCl, 0.32 m KCl, ±0.2 m HCl and/or 4 wt% S). The experiments were conducted in Au97Cu3 alloy capsules allowing the simultaneous determination of apparent Au and Cu solubilities in the liquid and the vapor phase. Though the apparent metal solubilities were strongly affected by the addition of HCl and S in both phases, all three elements were found to preferentially partition to a liquid phase at all studied conditions with an increasing degree of preference for the liquid in the following order Au < Cu < Mo. The presence of HCl and S did not have a significant effect on the liquid/vapor partition coefficients of either Au or Cu, whereas the presence of HCl slightly shifted the partitioning of Mo in favor of the vapor. Ore metal partition coefficients normalized to that of Na (Ki-Naliq/vap =Diliq/vap /DNaliq/vap) fall in the following ranges respectively for each studied metal: KAu-Naliq/vap = 0.20 ± 0.07-0.50 ± 0.19 (1σ); KCu-Naliq/vap = 0.36 ± 0.12-0.76 ± 0.22; KMo

  19. Soil-Air Partitioning of Polychlorinated Biphenyls and Total Dichloro-Diphenyl-Trichloroethanes

    Yaping Zhang; Erping Bi; Honghan Chen


    Soil-air partitioning is an important diffusive process that affects the environmental fate of organic compounds and human health. In this review, factors affecting the soil-air partitioning of polychlorinated biphenyls (PCBs) and total dichloro-diphenyl-trichloroethanes (p,p’-and o,p’-isomers of DDT, DDD, and DDE) are discussed. Hydrophobicity is an important factor that influences soil-air partition coefficients (KSA), and its effect can be explained through enthalpy of phase change for soil-air partitioning transfer (ΔHSA). For more hydrophobic compounds, a sharp increase in the KSA of PCBs and organochlorines can be seen in the early aging period. During the aging period, the temperature has a significant effect on the more hydrophobic organic compounds. The content and properties of soil or-ganic matter influence the KSA of the target compounds. Generally, KSA decreases with increasing rela-tive humidity in soils. The linear trend between KSA and temperature (T) changes at 0 °C. Freezing the air or soil in experiments would change the research results. On the basis of factors influencing soil-air partitioning, a multipleparameter (T, organic carbon fraction (fOC), and octanol-air partition coefficient (KOA)) model is put forward to predict the KSA values for PCBs and total DDTs.

  20. Molecular features determining different partitioning patterns of papain and bromelain in aqueous two-phase systems.

    Rocha, Maria Victoria; Nerli, Bibiana Beatriz


    The partitioning patterns of papain (PAP) and bromelain (BR), two well-known cysteine-proteases, in polyethyleneglycol/sodium citrate aqueous two-phase systems (ATPSs) were determined. Polyethyleneglycols of different molecular weight (600, 1000, 2000, 4600 and 8000) were assayed. Thermodynamic characterization of partitioning process, spectroscopy measurements and computational calculations of protein surface properties were also carried out in order to explain their differential partitioning behavior. PAP was observed to be displaced to the salt-enriched phase in all the assayed systems with partition coefficients (KpPAP) values between 0.2 and 0.9, while BR exhibited a high affinity for the polymer phase in systems formed by PEGs of low molecular weight (600 and 1000) with partition coefficients (KpBR) values close to 3. KpBR values resulted higher than KpPAP in all the cases. This difference could be assigned neither to the charge nor to the size of the partitioned biomolecules since PAP and BR possess similar molecular weight (23,000) and isoelectric point (9.60). The presence of highly exposed tryptophans and positively charged residues (Lys, Arg and His) in BR molecule would be responsible for a charge transfer interaction between PEG and the protein and, therefore, the uneven distribution of BR in these systems.

  1. Ontology Partitioning: Clustering Based Approach

    Soraya Setti Ahmed


    Full Text Available The semantic web goal is to share and integrate data across different domains and organizations. The knowledge representations of semantic data are made possible by ontology. As the usage of semantic web increases, construction of the semantic web ontologies is also increased. Moreover, due to the monolithic nature of the ontology various semantic web operations like query answering, data sharing, data matching, data reuse and data integration become more complicated as the size of ontology increases. Partitioning the ontology is the key solution to handle this scalability issue. In this work, we propose a revision and an enhancement of K-means clustering algorithm based on a new semantic similarity measure for partitioning given ontology into high quality modules. The results show that our approach produces meaningful clusters than the traditional algorithm of K-means.

  2. Study on Solubility and Stability of Rifapentine%利福喷丁的溶解性与稳定性考察

    折胜利; 罗兰; 吕顺忠; 古丽再努尔·吐尔逊; 蒋岳华; 宋兴华


    OBJECTIVE: To study the solubility and stability of rifapentine, and to lay a good foundation for the further development of new dosage form of it. METHODS: The solubility of rifapentine in 11 solvents was determined by UV spectrophotome-try, and solubilization effects of 4 kinds of solubilizers on it were investigated. The apparent oil/water partition coefficients of hex-ane and n-caprylic alcohol were investigated, and the stability of it was determined under high temperature, high humidity and light. RESULTS: Rifapentine showed good solubility in chlorofoim with solubility of 13.076 mg·L‐1; it showed poor solubility in water with solubility of 3.046 mg·L‐1. Tween-80 played strong solubilization roles and the solubility was up to 823 mg·L‐1. The apparent oil/water partition coefficients in hexane and n-caprylic alcohol were 4.778 ± 0.41 and 17.441 2 ± 2.79. Color and the content of main components among stability index had changed. CONCLUSION: Rifapentine shows strong fat-solubility and poor water-solubility, and suitable solubilizer can improve the solubility of it. It is not stable under high temperature, high humidity and light.%目的:考察利福喷丁的溶解性及其稳定性,为开发其新剂型奠定基础.方法:采用紫外分光先度法测定利福喷丁在11种溶剂中的溶解度及研究4种增溶剂对其的增溶作用;考察其在正己烷和正辛醇中的表观油水分配系数及在高湿、高温、光照条件下的稳定性.结果:利福喷丁在三氯甲烷中溶解性较好,溶解度为13.076 mg·L-1,在水中溶解性较差,为3.046 mg·L-1;吐温-80对其增溶作用较强,溶解度达到823 mg·L-1;在正已烷和正辛醇中的表观油水分配系数分别为4.778±0.41、17.441 2±2.79;稳定性指标中色泽和主药含量在考察期内均有变化.结论:利福喷丁的脂溶性强、水溶性差,合适的增溶剂对其有一定的增溶作用,其在高温、高湿、光照条件下不太稳定.

  3. Optimizing solubility: kinetic versus thermodynamic solubility temptations and risks.

    Saal, Christoph; Petereit, Anna Christine


    The aim of this study was to assess the usefulness of kinetic and thermodynamic solubility data in guiding medicinal chemistry during lead optimization. The solubility of 465 research compounds was measured using a kinetic and a thermodynamic solubility assay. In the thermodynamic assay, polarized-light microscopy was used to investigate whether the result referred to the crystalline or to the amorphous compound. From the comparison of kinetic and thermodynamic solubility data it was noted that kinetic solubility measurements frequently yielded results which show considerably higher solubility compared to thermodynamic solubility. This observation is ascribed to the fact that a kinetic solubility assay typically delivers results which refer to the amorphous compound. In contrast, results from thermodynamic solubility determinations more frequently refer to a crystalline phase. Accordingly, thermodynamic solubility data--especially when used together with an assessment of the solid state form--are deemed to be more useful in guiding solubility optimization for research compounds.

  4. Discretized configurations and partial partitions

    Abrams, Aaron; Hower, Valerie


    We show that the discretized configuration space of $k$ points in the $n$-simplex is homotopy equivalent to a wedge of spheres of dimension $n-k+1$. This space is homeomorphic to the order complex of the poset of ordered partial partitions of $\\{1,\\...,n+1\\}$ with exactly $k$ parts. We also compute the Euler characteristic in two different ways, thereby obtaining a topological proof of a combinatorial recurrence satisfied by the Stirling numbers of the second kind.

  5. Metal-silicate Partitioning and Its Role in Core Formation and Composition on Super-Earths

    Schaefer, Laura; Jacobsen, Stein B.; Remo, John L.; Petaev, M. I.; Sasselov, Dimitar D.


    We use a thermodynamic framework for silicate-metal partitioning to determine the possible compositions of metallic cores on super-Earths. We compare results using literature values of the partition coefficients of Si and Ni, as well as new partition coefficients calculated using results from laser shock-induced melting of powdered metal-dunite targets at pressures up to 276 GPa, which approaches those found within the deep mantles of super-Earths. We find that larger planets may have little to no light elements in their cores because the Si partition coefficient decreases at high pressures. The planet mass at which this occurs will depend on the metal-silicate equilibration depth. We also extrapolate the equations of state (EOS) of FeO and FeSi alloys to high pressures, and present mass–radius diagrams using self-consistent planet compositions assuming equilibrated mantles and cores. We confirm the results of previous studies that the distribution of elements between mantle and core will not be detectable from mass and radius measurements alone. While observations may be insensitive to interior structure, further modeling is sensitive to compositionally dependent properties, such as mantle viscosity and core freeze-out properties. We therefore emphasize the need for additional high pressure measurements of partitioning as well as EOSs, and highlight the utility of the Sandia Z-facilities for this type of work.

  6. Liposome and protein-water partitioning of polybrominated diphenyl ethers (PBDEs).

    Endo, Satoshi; Mewburn, Ben; Escher, Beate I


    Bioaccumulation of polybrominated diphenyl ethers (PBDEs) in marine and terrestrial organisms is of great environmental concern. Understanding the partitioning of PBDEs to biological phases is crucial for elucidating their bioaccumulation behavior. In this study, partitioning coefficients of PBDEs from water to phospholipid liposomes (K(lipw)) and to bovine serum albumin (BSA) (K(BSAw)) were measured using a polymer depletion method. K(lipw) values measured in two laboratories are in an excellent agreement (within 0.14 log units), indicating a high method repeatability. The values of log K(lipw) and log K(BSAw) are in the range of 6.3-8.2 and 5.1-7.0, respectively, representing the highest of these partition coefficients measured to date. Log K(lipw) values for PBDEs are similar to the log of the octanol-water partition coefficients (K(ow)) (log K(lipw)-log K(ow)=-0.06±0.23; mean±SD of 7 congeners), consistent with the data of chlorobenzenes and polychlorinated biphenyls (PCBs) reported in the literature. No hydrophobicity cutoff was observed for partitioning to the liposome membrane. Log K(BSAw) values for PBDEs increase linearly with log K(ow) and do not follow the non-linear trend observed for polycyclic aromatic hydrocarbons (PAHs). This difference between PBDEs and PAHs suggests specific binding mechanisms to serum albumin even for hydrophobic compounds.

  7. Soluble CD163

    Parkner, Tina; Sørensen, L P; Nielsen, A R


    Soluble CD163 (sCD163) was recently identified as a strong risk marker for developing type 2 diabetes. We hypothesised that sCD163 independently associates with insulin resistance.......Soluble CD163 (sCD163) was recently identified as a strong risk marker for developing type 2 diabetes. We hypothesised that sCD163 independently associates with insulin resistance....

  8. On higher spin partition functions

    Beccaria, M


    We observe that the partition function of the set of all free massless higher spins s=0,1,2,3,... in flat space is equal to one: the ghost determinants cancel against the "physical" ones or, equivalently, the (regularized) total number of degrees of freedom vanishes. This reflects large underlying gauge symmetry and suggests analogy with supersymmetric or topological theory. The Z=1 property extends also to the AdS background, i.e. the 1-loop vacuum partition function of Vasiliev theory is equal to 1 (assuming a particular regularization of the sum over spins); this was noticed earlier as a consistency requirement for the vectorial AdS/CFT duality. We find that Z=1 is also true in the conformal higher spin theory (with higher-derivative d^{2s} kinetic terms) expanded near flat or conformally flat S^4 background. We also consider the partition function of free conformal theory of symmetric traceless rank s tensor field which has 2-derivative kinetic term but only scalar gauge invariance in flat space. This non...

  9. Aqueous solubilities of five N-(diethylaminothiocarbonyl)benzimido derivatives at T = 298.15 K.

    Schröder, Bernd; Martins, Mónia A R; Coutinho, João A P; Pinho, Simão P


    N-(diethylaminothiocarbonyl)benzimido derivatives are polar multifunctional substances. A set of these compounds was synthesised by successive substitution on the enamine side, resulting in similar substances with different polarities, providing a set of model compounds with respect to the study of substituent effects on physico-chemical properties. Experimental aqueous solubility data, at T = 298.15 K, of N-(diethylaminothiocarbonyl)benzamidine, PhCNH2NCSNEt2 (1),N-(diethylaminothiocarbonyl)-N'-phenylbenzamidine, PhCNHPhNCSNEt2 (2), N-(diethylaminothiocarbonyl)-N'-monoethylbenzamidine, PhCNHEtNCSNEt2 (3), N-(diethylaminothiocarbonyl)-N',N'-diethylbenzamidine, PhCNEt2NCSNEt2 (4), and N-(diethylaminothiocarbonyl)benzimido ethylester, PhCOEtNCSNEt2 (5) were measured at T = 298.15 K. The obtained data are supplemented by COSMO-RS aqueous solubility predictions as well as other environmentally important partition coefficients. This information is shown in a two-dimensional chemical space diagram, providing indications about the compartment into which the bulk of the compounds is likely to concentrate. The expected quality of COSMO-RS predictions for this type of screening exercise is illustrated on a set of pesticides with established thermophysical property data.

  10. Partitioning regularity of non-ionic organic mixtures in organic phase/water system


    The partitioning regularity of nonionic organic mixtures in organic phase/water system is revealed. The equation for calculating the partition coefficients of mixtures (KMD), together with the determination model, is derived from the equilibrium partitioning models (EPMs). Based on these derived equations, the KMD values of 20 mixtures conraining halogenated benzenes are obtained. The results show that stronger hydrophobicity of an individual chemical in the mixture results in the stronger hydrophobicity of the mixture and the greater the proportion of this chemical, the stronger the hydrophobicity of the mixture will be. This partitioning regularity is helpful to the study of the toxicity for mixtures and the environmental behavior, such as transfer or accumuiation, for mixed organic pollutants.``

  11. Partition Equilibrium on the Interface Between a Charged Membrane and a Mixed Electrolyte Aqueous Solution


    Ionic partition equilibrium on a charged membrane immersed in a mixed electrolyte solution was systematically investigated and several models were established for the determination of partition coefficients. On the basis of theoretical models, the effects of the concentration ratio λ of the fixed group(charged density) to reference electrolyte, the concentration ratio η between the two electrolytes existing in the solution and the valence of the electrolyte ions on the partition equilibrium in a positively charged membrane were analyzed and simulated within the chosen parameters in detail. The obtainable results can also be applicable to a sytem of mixed electrolytes contacting with a negatively charged membrane. The theoretical calculations were confirmed with the experimental data of model mixed electrolytes, NaCl+HCl and CaCl2+NaCl partitioned in the system of self-made negatively charged membrane-sulphonated poly(phenylene oxide)(SPPO) with different charge densities.

  12. The influence of aerosol size and organic carbon content on gas/particle partitioning of polycyclic aromatic hydrocarbons (PAHs)

    Offenberg, J.H.; Baker, J.E. [University of Maryland, Solomons, MD (United States). Chesapeake Biological Lab.


    Concentrations of polycyclic aromatic hydrocarbons (Paths) were measured on size segregated airborne particulate matter and in the gas phase during 12h periods in urban Chicago and over southern Lake Michigan during July 1994 and January 1995 as part of the atmospheric exchange over lakes and oceans (AEOLOS) project. In the 19 paired gas phase and size segregated particle samples, partition coefficients of polycyclic aromatic hydrocarbons are well correlated with the sub-cooled liquid vapor pressure, (p{sub l}{sup 0}) within an aerosol size class. However, partition coefficients differ systematically according to particle size and aerosol organic carbon content. Approximately 68% of the observed variability in measured PAH partition coefficients is explained by a three dimensional multiple linear regression that includes vapor pressure of the compound of interest, aerosol particle aerodynamic equivalent diameter, aerosol organic carbon content and interaction terms. However, addition of both particle size and the fraction organic carbon terms, while statistically significant, appear to be of minimal importance in improving our ability to model gas/particle partitioning in the atmosphere. The influence of either particle size or fraction organic carbon is nearly as large as the calculated random error in partition coefficients, and suggests that an important factor in predicting gas/particle partitioning has not yet been incorporated in the current model. [author].

  13. Partitioning of hydrophobic organic contaminants between polymer and lipids for two silicones and low density polyethylene

    Smedes, Foppe; Rusina, Tatsiana P.; Beeltje, Henry


    concentrations in other (defined) media, which however requires appropriate polymer to media partition coefficients. We determined thus polymer-lipid partition coefficients (KPL) of various PCB, PAH and organochlorine pesticides by equilibration of two silicones and low density polyethylene (LDPE) with fish oil...... and Triolein at 4 °C and 20 °C. We observed (i) that KPL was largely independent of lipid type and temperature, (ii) that lipid diffusion rates in the polymers were higher compared to predictions based on their molecular volume, (iii) that silicones showed higher lipid diffusion and lower lipid sorption...... compared to LDPE and (iv) that absorbed lipid behaved like a co-solute and did not affect the partitioning of HOC at least for the smaller molecular size HOC. The obtained KPL can convert measured equilibrium concentrations in passive sampling polymers into equilibrium concentrations in lipid, which...

  14. Multidimensional extremal dependence coefficients


    Extreme values modeling has attracting the attention of researchers in diverse areas such as the environment, engineering, or finance. Multivariate extreme value distributions are particularly suitable to model the tails of multidimensional phenomena. The analysis of the dependence among multivariate maxima is useful to evaluate risk. Here we present new multivariate extreme value models, as well as, coefficients to assess multivariate extremal dependence.

  15. Predicting sediment sorption coefficients for linear alkylbenzenesulfonate congeners from polyacrylate-water partition coefficients at different salinities.

    Rico Rico, A.; Droge, S.T.J.; Hermens, J.L.M.


    The effect of the molecular structure and the salinity on the sorption of the anionic surfactant linear alkylbenzenesulfonate (LAS) to marine sediment has been studied. The analysis of several individual LAS congeners in seawater and of one specific LAS congener at different dilutions of seawater wa

  16. Evidence for equilibrium conditions during the partitioning of nickel between olivine and komatiite liquids.

    Budahn, J.R.


    Olivine-liquid partition coefficients for Ni(DNi), calculated from Ni vs MgO abundance variations in komatiite series basalts, compare favourably with experimentally determined values, if Ni variations in olivine-controlled basalts can be modelled with an equation that assumes equilibrium between the entire olivine crystal and its coexisting liquid.-J.A.Z.

  17. Biorelevant solubility of poorly soluble drugs: rivaroxaban, furosemide, papaverine and niflumic acid.

    Takács-Novák, Krisztina; Szőke, Vera; Völgyi, Gergely; Horváth, Péter; Ambrus, Rita; Szabó-Révész, Piroska


    In this work the biorelevant solubility of four drugs representing different acid-base property, wide range of lipohilicity and low aqueous solubility was studied. The equilibrium solubility of rivaroxaban (non-ionizable), furosemide (acid), papaverine (base) and niflumic acid (ampholyte) was determined in simulated gastric fluid (SGF pH 1.2), in simulated intestinal fluid fasted state (FaSSIF pH 6.5) and fed state (FeSSIF pH 5.0) and their corresponding blank buffers at a temperature of 37 °C using saturation shake-flask method. The concentration was measured by optimized HPLC analysis. The solubilizing effect of bile acid/lipid micelles as additive components of biorelevent media (BRM) is expressed with the solubility ratio (SR: SBRM/Sblank buffer) and the food effect was estimated from SFeSSIF/SFaSSIF coefficient. It was revealed that ionization plays primarily role in solubility of compounds which undergo ionization in BRM. The solubilizing effect in FaSSIF was marginal for the neutral compound (rivaroxaban) and for molecules are anionic at pH 6.5 (furosemide and niflumic acid). The higher concentration of solubilizing agents in FeSSIF improved the solubility of papaverine carrying positive charge and niflumic acid being partially zwitterionic at pH 5.0.

  18. Solubility of drugs in aqueous polymeric solution: effect of ovalbumin on microencapsulation process.

    Aziz, Hesham Abdul; Tan, Yvonne Tze Fung; Peh, Kok Khiang


    Microencapsulation of water-soluble drugs using coacervation-phase separation method is very challenging, as these drugs partitioned into the aqueous polymeric solution, resulting in poor drug entrapment. For evaluating the effect of ovalbumin on the microencapsulation of drugs with different solubility, pseudoephedrine HCl, verapamil HCl, propranolol HCl, paracetamol, and curcuminoid were used. In addition, drug mixtures comprising of paracetamol and pseudoephedrine HCl were also studied. The morphology, encapsulation efficiency, particle size, and in vitro release profile were investigated. The results showed that the solubility of the drug determined the ratio of ovalbumin to be used for successful microencapsulation. The optimum ratios of drug, ovalbumin, and gelatin for water-soluble (pseudoephedrine HCl, verapamil HCl, and propranolol HCl), sparingly water-soluble (paracetamol), and water-insoluble (curcuminoid) drugs were found to be 1:1:2, 2:3:5, and 1:3:4. As for the drug mixture, the optimum ratio of drug, ovalbumin, and gelatin was 2:3:5. Encapsulated particles prepared at the optimum ratios showed high yield, drug loading, entrapment efficiency, and sustained release profiles. The solubility of drug affected the particle size of the encapsulated particle. Highly soluble drugs resulted in smaller particle size. In conclusion, addition of ovalbumin circumvented the partitioning effect, leading to the successful microencapsulation of water-soluble drugs.

  19. Radionuclide Partitioning in an Underground Nuclear Test Cavity

    Rose, T P; Hu, Q; Zhao, P; Conrado, C L; Dickerson, R; Eaton, G F; Kersting, A B; Moran, J E; Nimz, G; Powell, B A; Ramon, E C; Ryerson, F J; Williams, R W; Wooddy, P T; Zavarin, M


    : chemical volatility effects that occur during the initial plasma condensation, and groundwater remobilization that occurs over a much longer time frame. Fission product partitioning is very sensitive to the early cooling history of the test cavity because the decay of short-lived (t{sub 1/2} < 1 hour) fission-chain precursors occurs on the same time scale as melt glass condensation. Fission product chains that include both volatile and refractory elements, like the mass 99, 125, and 129 chains, can show large variations in partitioning behavior depending on the cooling history of the cavity. Uranium exhibits similar behavior, though the chemical processes are poorly understood. The water temperature within the Chancellor cavity remains elevated (75 C) more than two decades after the test. Under hydrothermal conditions, high solubility chemical species such as {sup 125}Sb and {sup 129}I are readily dissolved and transported in solution. SEM analyses of melt glass samples show clear evidence of glass dissolution and secondary hydrothermal mineral deposition. Remobilization of {sup 99}Tc is also expected during hydrothermal activity, but moderately reducing conditions within the Chancellor cavity appear to limit the transport of {sup 99}Tc. It is recommended that the results from this study should be used together with the IAEA data to update the range in partitioning values for contaminant transport models at the Nevada National Security Site (formerly known as the Nevada Test Site).

  20. Intrinsic energy partition in fission

    Mirea M.


    Full Text Available The intrinsic energy partition between two complementary fission fragments is investigated microscopically. The intrinsic excitation energy of fission fragments is dynamically evaluated in terms of the time-dependent pairing equations. These equations are corroborated with two conditions. One of them fixes the number of particles and the other separates the pairing active spaces associated to the two fragments in the vicinity of the scission configuration. The excitation energy in a wide distribution of fission fragments is calculated for the 234U parent nucleus.

  1. Prestarlike functions with negative coefficients

    H. Silverman


    Full Text Available The extreme points for prestarlike functions having negative coefficients are determined. Coefficient, distortion and radii of univalence, starlikeness, and convexity theorems are also obtained.

  2. Solubility Advantage (and Disadvantage) of Pharmaceutical Amorphous Solid Dispersions.

    Huang, Siyuan; Mao, Chen; Williams, Robert O; Yang, Chia-Yi


    The solubility of a drug is ultimately governed by its chemical potential as it is present in the undissolved solute. For a pharmaceutical amorphous solid dispersion (ASD), its solubility depends on the state and composition of the undissolved solute when the ASD is equilibrated with water. Concerning the undissolved solute phase that can contain up to 3 components (drug, polymer, and water), we developed a complete thermodynamic model to calculate the chemical potential of a drug in the multicomponent, amorphous system. This approach enables the estimation of the true solubility advantage of ASD from calorimetric measurements and moisture sorption isotherms. Both theoretical estimation and experimental studies, using indomethacin (IMC)/Eudragit E ASD systems, show that the solubility advantage of the amorphous IMC is significantly reduced through ASD formation and water partitioning. For the ASD with 70% drug loading, the solubility of IMC is lower than its crystalline counterpart. Our results show that stabilization through the ASD formation and water sorption can be manifested by the lowering of drug solubility; they demonstrate that the core property in ASD development is the drug chemical potential, which is essentially the thermodynamic driving force and can be quantitated using the model presented in this work.

  3. Effect of demulsifier partitioning on the destabilization of water-in-oil emulsions

    Kim, Y.H.; Wasan, D.T. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering


    The factors affecting the demulsification and interfacial behavior of water-in-oil emulsions in the presence of oil-soluble demulsifiers were investigated. Using both model water-in-oil and water-in-crude oil emulsion systems with demulsifiers with different chemical structures, the effects of demulsifier partitioning on the interfacial and film rheological properties were studied. The experimental results were compared and related with the demulsifier performance. There is a one-to-one correlation between the performance of demulsifier and the interfacial activity of the partitioned demulsifier; the partitioned demulsifier components exhibit an increase in static and dynamic interfacial activity, low dynamic interfacial and film tension, and a low film dilational modulus with a high adsorption rate - low interfacial tension gradient (Marangoni-Gibbs stabilizing effect) and have excellent demulsification performance.

  4. Gorenstein Hilbert Coefficients

    Khoury, Sabine El


    We prove upper and lower bounds for all the coefficients in the Hilbert Polynomial of a graded Gorenstein algebra $S=R/I$ with a quasi-pure resolution over $R$. The bounds are in terms of the minimal and the maximal shifts in the resolution of $R$ . These bounds are analogous to the bounds for the multiplicity found in \\cite{S} and are stronger than the bounds for the Cohen Macaulay algebras found in \\cite{HZ}.

  5. On the partition dimension of unicyclic graphs

    Rodriguez-Velazquez, Juan A; Fernau, Henning


    Given an ordered partition $\\Pi =\\{P_1,P_2, ...,P_t\\}$ of the vertex set $V$ of a connected graph $G=(V,E)$, the \\emph{partition representation} of a vertex $v\\in V$ with respect to the partition $\\Pi$ is the vector $r(v|\\Pi)=(d(v,P_1),d(v,P_2),...,d(v,P_t))$, where $d(v,P_i)$ represents the distance between the vertex $v$ and the set $P_i$. A partition $\\Pi$ of $V$ is a \\emph{resolving partition} if different vertices of $G$ have different partition representations, i.e., for every pair of vertices $u,v\\in V$, $r(u|\\Pi)\

  6. On the partition dimension of trees

    Rodriguez-Velazquez, Juan A; Lemanska, Magdalena


    Given an ordered partition $\\Pi =\\{P_1,P_2, ...,P_t\\}$ of the vertex set $V$ of a connected graph $G=(V,E)$, the \\emph{partition representation} of a vertex $v\\in V$ with respect to the partition $\\Pi$ is the vector $r(v|\\Pi)=(d(v,P_1),d(v,P_2),...,d(v,P_t))$, where $d(v,P_i)$ represents the distance between the vertex $v$ and the set $P_i$. A partition $\\Pi$ of $V$ is a \\emph{resolving partition} of $G$ if different vertices of $G$ have different partition representations, i.e., for every pair of vertices $u,v\\in V$, $r(u|\\Pi)\

  7. Geological and physicochemical controls of the spatial distribution of partition coefficients for radionuclides (Sr-90, Cs-137, Co-60, Pu-239,240 and Am-241) at a site of nuclear reactors and radioactive waste disposal (St. Petersburg region, Russian Federation).

    Rumynin, Vyacheslav G; Nikulenkov, Anton M


    The paper presents a study of the sorption properties of sediments of different geological ages and lithological types, governing radionuclide retention in the subsurface (up to 160 m beneath the surface) within the area of potential influence of the Northwestern Center of Atomic Energy (NWCAE), St. Petersburg region, RF. The focus of this work is mostly on the sedimentary rocks of two types, i.e., weakly cemented sandstone and lithified clay formations of Cambrian and Vendian series. The first lithological unit is associated with a groundwater reservoir (Lomonosov aquifer), and the second one, with both a relative aquitard in the upper part of the Vendian formation (Kotlin clay) and a regional aquifer (Gdov aquifer) in the lower part of the formation. The main mechanisms responsible for the variability of the sorption distribution coefficient (Kd, defined as the ratio of the concentration of solute on solid phase to its concentration in solution at equilibrium) was identified for radionuclides such as Sr-90, Cs-137, Co-60, Pu-239,240, and Am-241. It was shown that the main factors contributing to the chemical heterogeneity of the Cambrian sandstone were related to the presence of secondary minerals (iron and magnesium oxides and hydroxides produced by the weathering process) in trace amounts, forming correlated layer structures. The statistical analysis of nonlinear isotherms confirmed this conclusion. For the Vendian formation, a determinate trend was established in the Kd change over depth as a result of temporal trends in the sedimentation process and pore-water chemistry. The geostatistical characteristics and the spatial correlation models for describing linear sorption of different radionuclides are not identical, and the exhibition of chemical heterogeneity of sedimentary rock of a particular lithological type depends on radionuclide chemistry. Moreover, variogram analysis for some Kd data sets (both in Cambrian and Vendian formations) demonstrates the

  8. Hardware/software partitioning in Verilog.


    We propose in this paper an algebraic approach to hardware/software partitioning in Verilog HDL. We explore a collection of algebraic laws for Verilog programs, from which we design a set of syntax-based algebraic rules to conduct hardware/software partitioning. The co-specification language and the target hardware and software description languages are specific subsets of Verilog, which brings forth our successful verification for the correctness of the partitioning process by algebra of Ver...

  9. Data Partitioning View of Mining Big Data

    Zhang, Shichao


    There are two main approximations of mining big data in memory. One is to partition a big dataset to several subsets, so as to mine each subset in memory. By this way, global patterns can be obtained by synthesizing all local patterns discovered from these subsets. Another is the statistical sampling method. This indicates that data partitioning should be an important strategy for mining big data. This paper recalls our work on mining big data with a data partitioning and shows some interesti...

  10. Evolution of Task Partitioning in Swarm Robotics

    Ferrante, Eliseo,; Duenez-Guzman, E.; Turgut, A. E.; Wenseleers, Tom


    International audience; Task-partitioning refers to the process whereby a task is divided into two or more sub-tasks. Through task partitioning both efficiency and effectiveness can be improved provided the right environmental conditions. We synthesize self-organized task partitioning behaviors for a swarm of mobile robots using artificial evolution. Through validation experiments, we show that the synthesized behaviors exploits behavioral specialization despite being based on homogeneous ind...

  11. The grand partition function of dilute biregular solutions

    Nagamori, Meguru; Ito, Kimihisa; Tokuda, Motonori


    It has been demonstrated that the grand partition function (GPF) of biregular solutions contains in one single equation such thermodynamic principles as Henry's law, Raoult's law, the Gibbs-Duhem relation, Raoultian activity coefficients and their finite power series, Wagner's rec-iprocity, Schenck-Frohberg-Steinmetz's interchange, Lupis-Elliott's additivity, Mori-Morooka's disparity, and Darken's quadratic formalism. The logarithm of the Raoultian activity coefficient of species i, In γi should not be expressed by the Taylor series expansion, lest its truncation infringe the Gibbs-Duhem equation. The GPF methodology establishes that In γi, is not a vector but a scalar point function, free from any path dependence. While Darken's quadratic formalism employs three parameters to describe a ternary solution, the present biregularity approximation offers an alternative using seven empirical parameters, in case better accuracy is needed.

  12. Solid-liquid two-phase partitioning bioreactors (TPPBs) operated with waste polymers. Case study: 2,4-dichlorophenol biodegradation with used automobile tires as the partitioning phase.

    Tomei, M Concetta; Annesini, M Cristina; Daugulis, Andrew J


    Used automobile tire pieces were tested for their suitability as the sequestering phase in a two-phase partitioning bioreactor to treat 2,4-dichlorophenol (DCP). Abiotic sorption tests and equilibrium partitioning tests confirmed that tire "crumble" possesses very favourable properties for this application with DCP diffusivity (4.8 × 10(-8) cm(2)/s) and partition coefficient (31) values comparable to those of commercially available polymers. Biodegradation tests further validated the effectiveness of using waste tires to detoxify a DCP solution, and allow for enhanced biodegradation compared to conventional single-phase operation. These results establish the potential of using a low-cost waste material to assist in the bioremediation of a toxic aqueous contaminant.

  13. Compositional controls on the partitioning of U, Th, Ba, Pb, SR and Zr between clinopyroxene and haplobasaltic melts: Implications for uranium series disequilibria in basalts

    Lundstrom, C. C.; Shaw, H. F.; Ryerson, F. J.; Phinney, D. L.; Gill, J. B.; Williams, Q.


    The partitioning of U, Th, Pb, Sr, Zr and Ba between coexisting chromian diopsides and haplobasaltic liquids at oxygen fugacities between the iron-wustite buffer and air at 1285 C has been characterized using secondary ion mass spectrometry. The partition coefficients for Th, U and Zr show a strong dependence on the Al and Na content of the clinopyroxene. A good correlation between Al-IV and DTh exists for all recent Th partitioning studies, providing a simple explanation for the two order of magnitude variation in DTh observed in this and previous studies. Because mantle clinopyroxenes generally have greater than 5 wt% Al2O3, we suggest that the relevant partition coefficients for U and Th are between 0.01 and 0.02. While variations in Al and Na in clinopyroxene affect the absolute value of the Th and U partition coefficients, they have no effect on their ratio, DTh/DU. Our results reinforce the inference that equilibrium partioning of U and Th between clinopyroxene and melt cannot explain the observed Th-230 excesses in basalts. Indeed, under the oxygen fugacities relevant to mid-ocean ridge basalts (MORB) petrogenesis, clinopyroxene has little ability to fractionate U from Th (DTh/D(sub U less than 2), implying that chemical disequilibrium between melt and wall rock during transport is not required to preserve Th-230 excess generated in the garnet stability field. If the Ba partition coefficient serves as an analog for Ra and the partition coefficient of U(5+) serves as an analog for Pa(5+), then Ra-226 and Pa-231 excesses can be generated by clinopyroxene-melt partitioning. Using compositionally dependent partition coefficients, a melting model is used to show that equilibrium porous flow can explain variation in uranium series activities from the East Pacific Rise by varying the depth of melting.

  14. Partitioning Behavior of Organic Contaminants in Carbon Storage Environments: A Critical Review

    Burant, Aniela; Lowry, Gregory V; Karamalidis, Athanasios K


    Carbon capture and storage is a promising strategy for mitigating the CO{sub 2} contribution to global climate change. The large scale implementation of the technology mandates better understanding of the risks associated with CO{sub 2} injection into geologic formations and the subsequent interactions with groundwater resources. The injected supercritical CO{sub 2} (sc-CO{sub 2}) is a nonpolar solvent that can potentially mobilize organic compounds that exist at residual saturation in the formation. Here, we review the partitioning behavior of selected organic compounds typically found in depleted oil reservoirs in the residual oil–brine–sc-CO{sub 2} system under carbon storage conditions. The solubility of pure phase organic compounds in sc-CO{sub 2} and partitioning of organic compounds between water and sc-CO{sub 2} follow trends predicted based on thermodynamics. Compounds with high volatility and low aqueous solubility have the highest potential to partition to sc-CO{sub 2}. The partitioning of low volatility compounds to sc-CO{sub 2} can be enhanced by co-solvency due to the presence of higher volatility compounds in the sc-CO{sub 2}. The effect of temperature, pressure, salinity, pH, and dissolution of water molecules into sc-CO{sub 2} on the partitioning behavior of organic compounds in the residual oil-brine-sc-CO{sub 2} system is discussed. Data gaps and research needs for models to predict the partitioning of organic compounds in brines and from complex mixtures of oils are presented. Models need to be able to better incorporate the effect of salinity and co-solvency, which will require more experimental data from key classes of organic compounds.

  15. Combinatorial set theory partition relations for cardinals

    Erdös, P; Hajnal, A; Rado, P


    This work presents the most important combinatorial ideas in partition calculus and discusses ordinary partition relations for cardinals without the assumption of the generalized continuum hypothesis. A separate section of the book describes the main partition symbols scattered in the literature. A chapter on the applications of the combinatorial methods in partition calculus includes a section on topology with Arhangel''skii''s famous result that a first countable compact Hausdorff space has cardinality, at most continuum. Several sections on set mappings are included as well as an account of

  16. Solubility Part 1

    Tantra, Ratna; Bolea, Eduardo; Bouwmeester, H.; Rey-Castro, Carlos; David, C.A.A.; Dogné, Jean Michel; Laborda, Francisco; Laloy, Julie; Robinson, Kenneth N.; Undas, A.K.; Zande, van der M.


    This chapter gives an overview of different methods that can potentially be used to determine the solubility of nanomaterials. In general, the methods presented can be broadly divided into four categories: separation methods, methods to quantify free ions, methods to quantify total dissolved

  17. Atmospheric occurrence, transport and gas-particle partitioning of polychlorinated biphenyls over the northwestern Pacific Ocean

    Wu, Zilan; Lin, Tian; Li, Zhongxia; Li, Yuanyuan; Guo, Tianfeng; Guo, Zhigang


    Ship-board air samples were collected during March to May 2015 from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) to explore the atmospheric occurrence and gas-particle partitioning of polychlorinated biphenyls (PCBs) when the westerly East Asian Monsoon prevailed. Total PCB concentrations in the atmosphere ranged from 56.8 to 261 pg m-3. Higher PCB levels were observed off the coast and minor temperature-induced changes showed that continuous emissions from East Asia remain as an important source to the regional atmosphere. A significant relationship between Koa (octanol-air partition coefficient) and KP (gas-particle partition coefficient) for PCBs was observed under continental air masses, suggesting that land-derived organic aerosols affected the PCB gas-particle partitioning after long-range transport, while an absence of this correlation was identified in marine air masses. The PCB partitioning cannot be fully explained by the absorptive mechanism as the predicted KP were found to be 2-3 orders of magnitude lower than the measured Kp, while the prediction was closely matched when soot adsorption was considered. The results suggested the importance of soot carbon as a transport medium for PCBs during their long-range transport and considerable impacts of continental outflows on PCBs across the downwind area. The estimated transport mass of particulate PCBs into the ECS and NWP totals 2333 kg during the spring, constituting ca. 17% of annual emission inventories of unintentionally produced PCB in China.

  18. Partition Behavior of Penicillin in Three-liquid-phase Extraction System

    谭显东; 季清荣; 常志东


    Partition behavior of penicillins G and V was studied in a novel three-liquid-phase extraction system, which is composed of butyl acetate (BA), polyethylene glycol (PEG), ammonia sulfate [(NH4)2SO4] and water (H2O). The main components in the top, middle and bottom phases are butyl acetate, polyethylene glycol aqueous solution and ammonia sulfate aqueous solution, respectively. Some parameters such as partition coefficients Di/j and mass fractions Ei ofpenicillins G and V were determined at the room temperature, respectively. Experimental efforts have been made to investigate the partition behavior of penicillin in the three-liquid-phase extraction system, including initial concentrations of phase-forming components [PEG and (NH4)2SO4], PEG molecular weight, pH, initial concentration of penicillin. The results indicated that penicillins G and V have the similar partition behavior. They preferentially distribute into the middle phase with the increase of initial concentration of phase-forming components and into the top phase with the decrease of pH, while partition coefficient Dm/b is hardly affected by pH value. The variation of PEG molecular weight has little effect on mass fractions of penicillin. The increase of initial concentration of penicillins G and V could lead to the increase of Dt/b, Dm/b and the decrease of Dt/m, while their mass fractions in all phases were almost independent on their initial concentrations.

  19. The Truth About Ballistic Coefficients

    Courtney, Michael


    The ballistic coefficient of a bullet describes how it slows in flight due to air resistance. This article presents experimental determinations of ballistic coefficients showing that the majority of bullets tested have their previously published ballistic coefficients exaggerated from 5-25% by the bullet manufacturers. These exaggerated ballistic coefficients lead to inaccurate predictions of long range bullet drop, retained energy and wind drift.

  20. Partition functions. I. Improved partition functions and thermodynamic quantities for normal, equilibrium, and ortho and para molecular hydrogen

    Popovas, A.; Jørgensen, U. G.


    Context. Hydrogen is the most abundant molecule in the Universe. Its thermodynamic quantities dominate the physical conditions in molecular clouds, protoplanetary disks, etc. It is also of high interest in plasma physics. Therefore thermodynamic data for molecular hydrogen have to be as accurate as possible in a wide temperature range. Aims: We here rigorously show the shortcomings of various simplifications that are used to calculate the total internal partition function. These shortcomings can lead to errors of up to 40 percent or more in the estimated partition function. These errors carry on to calculations of thermodynamic quantities. Therefore a more complicated approach has to be taken. Methods: Seven possible simplifications of various complexity are described, together with advantages and disadvantages of direct summation of experimental values. These were compared to what we consider the most accurate and most complete treatment (case 8). Dunham coefficients were determined from experimental and theoretical energy levels of a number of electronically excited states of H2. Both equilibrium and normal hydrogen was taken into consideration. Results: Various shortcomings in existing calculations are demonstrated, and the reasons for them are explained. New partition functions for equilibrium, normal, and ortho and para hydrogen are calculated and thermodynamic quantities are reported for the temperature range 1-20 000 K. Our results are compared to previous estimates in the literature. The calculations are not limited to the ground electronic state, but include all bound and quasi-bound levels of excited electronic states. Dunham coefficients of these states of H2 are also reported. Conclusions: For most of the relevant astrophysical cases it is strongly advised to avoid using simplifications, such as a harmonic oscillator and rigid rotor or ad hoc summation limits of the eigenstates to estimate accurate partition functions and to be particularly careful when