Flow pattern maps for particle-fluid mixture transport in a horizontal pipe - application of a three-layer model

A modified three-layer model was applied to model particle-fluid mixture flow in a horizontal pipe, the viscoelastic properties of carrier polymer solution were taken into consideration, and the Deborah number was used to calculate solid-fluid friction factor. An energy equation was applied to determine temperature distribution of carrier fluid along a horizontal pipe to accurately represent the rheological properties of carrier fluid. During the transport process, particles quickly settle out of carrier fluid and accumulate on pipe bottom forming a particle bed, so a particle bed load flow is observed. The transport mechanisms of particles in moving particle bed are govern by fluidization, which causes the height of this layer to be small and equal to 2～5 times of particle diameter. In addition, the pressure drop is composed of solid-fluid and solid-solid friction loss, which dominate the hydrodynamic performance at different stages.     

Observation of new cycloisomerization pattern of 1,5-bisallenes. Catalyst and substituent effects

In this paper a new cycloisomerization pattern of 1,5-bisallenes based on the catalyst and substituent effects has been reported. A range of seven-membered cross-conjugated trienes 7 would be obtained efficiently via the beta-H elimination and reductive elimination of the intermediates formed via cycloisomerization.     

Observation of a sequence of wetting transitions in the binary water+ethylene glycol monobutyl ether mixture

A homemade pendant drop/bubble tensiometer was assembled and applied to perform the surface-interfacial tension measurements for the binary water+ethylene glycol monobutyl ether (C4E1) mixture over the temperature range from 50 to 128 degrees C at 10 bar. The symbol CiEj is the abbreviation of a nonionic polyoxyethylene alcohol CiH2i+1(OCH2CH2)jOH. The wetting behavior of the C4E1-rich phase at the interface separating the gas and the aqueous phases was systematically examined according to the wetting coefficient calculated from the experimental results of surface/interfacial tensions. It was found that the C4E1-rich phase exhibits a sequence of wetting transitions, nonwetting-->partial wetting-->complete wetting, at the gas-water interface in the water+C4E1 system along with increasing the temperature, consistent with the conjecture of Kahlweit and Busse [J. Chem. Phys. 91, 1339 (1989)]. In addition, the relationship of the mutual solubility and the interfacial tension of the interface separating the C4E1-rich phase and the aqueous phase is discussed.     

Electrohydrodynamic instability in a binary mixture of cyanobiphenyls in a d.c. field

Electrohydrodynamic instability in a homeotropically oriented liquid crystal mixture, with positive dielectric anisotropy, has been studied under a d.c. electric field. Various studies on textures at different voltage were also made. The existence of charge injection, charge diffusion and convective flow of liquid in the liquid crystal cells was found. The effect of viscosity, dielectric anisotropy and other physical parameters on electric current through the sample cells, is discussed. A small change in phase transition temperature on application of an electric field was found in the thin cell of the sample material.     

Quantitative F NMR method validation and application to the quantitative analysis of a fluoro-polyphosphates mixture

Quantitative ¹⁹F NMR (QNMR) was developed and employed to determine the amounts of four kinds of fluoropolyphosphates (FPPs) in a mixture containing sodium monofluoro-phosphate (MFP), sodium monofluoro-dipolyphosphate (MFDPP), sodium monofluoro-tripolyphosphate (MFTPP) and sodium difluoro-tripolyphosphate (DFTPP). The amounts of these ingredients cannot be measured by high-performance liquid chromatography (HPLC) because no high-purity standard samples are available. The main parameter “delay time (d1) between two scans” of affecting the response of NMR signal was determined by measuring longitudinal relaxation time (T1) to be 25 s. By using NaF as an internal reference to measure the amount of MFP solution with known concentration and then to compare the deviation between experiment value and real value, a simple and effective approach for checking out the validity of ¹⁹F QNMR method was carried out. Six experiments with different mole ratios of NaF/MFP over 200 times were repeated and the relative standard deviation (R.S.D.) of results is less than 2.0%, the limit of detection of ¹⁹F QNMR can reach to 1.0 mmol/L. NaF was used as an internal reference for the quantitative analysis of FPPs mixture. The amount of each FPP in FPPs mixture obtained by ¹⁹F QNMR was calculated and the R.S.D.s of results were less than 4.81%.     

Visible light induced DNA-protein crosslinking in DNA-histone complex and sarcoma-180 chromatin in the presence of methylene blue

Formation of DNA-protein cross-links by the action of visible light in the presence of methylene blue was studied in calf thymus DNA-calf thymus histone complex and sarcoma-180 chromatin. The extent of cross-link formation decreases with a decrease in the histone to DNA ratio in the DNA-histone complex. In chromatin, it is at a maximum (93%) at a dye to DNA nucleotide ratio (D/P ratio) of 0.04 and is appreciable even at a very low dye concentration (75% at a D/P ratio of 0.0033). Sepharose 4B-CL column chromatography indicates that methylene blue acts as a mediator in the cross-linking process, but not as a linker in the DNA-protein cross-link. Dodecylsulphate-polyacrylamide gel electrophoresis patterns reveal that both histone and non-histone proteins are involved in cross-linking, but to a varied extent. Competition experiments with ethidium bromide demonstrated the necessity of intercalative binding of methylene blue in the formation of DNA--protein cross-links. Viscometric studies in 2 M NaCl indicate that the compact structure of chromatin is stabilized by cross-linking.     

Microdetermination of calcium and magnesium in a mixture

Summary A procedure is presented for the chemical separation and determination of mg quantities of calcium and magnesium, which is based on the selective carrying of calcium by ignited strontium sulphate leaving magnesium in the solution phase; the carried calcium is recovered by leaching with alcoholic sulphuric acid solution. Calcium and magnesium in the separated fractions are determined complexometrically using Eriochrome Black T as the indicator.

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Zusammenfassung Ein Verfahren zur chemischen Trennung und Bestimmung von mg-Mengen Calcium und Magnesium wird vorgeschlagen, wobei Ca selektiv mit geglühtem Strontiumsulfat abgetrennt wird, während Mg in Lösung bleibt. Ca wird mit alkoholischer Schwefelsäure eluiert. Beide Metalle werden getrennt gegen Eriochromschwarz T komplexometrisch titriert.

     

The ripple phase in a DMPC-water mixture. A dielectric investigation

The dielectric behaviour of a DMPC-water mixture has been investigated in the frequency range from 1 kHz to 10 MHz and in the temperature interval from 0 to 40°C over the crystalline-liquid crystalline phase transition temperatures. A model to explain the dielectric characteristics of the DMPC-water mixture as a function of frequency, and in general for each DPL-water mixture which displays a ripple phase, is proposed. The model is based on the assumption that a particular contribution to the total polarizability comes from the ripple deformation of the bilayer. This contribution is evaluated supposing strong interactions between the lipid head groups with the formation of in-phase domains of correlated electric dipoles. A further assumption relates the extension of the domains to a set of spatial modes, called ripplons, thermally activated in the ripple phase. By the ripplon dispersion relation, the dipole domain extensions (hence the polarizability), were made frequency dependent. The final result shows that the anomalous peak which appears in the permittivity at the ripple phase temperature interval is qualitatively well fitted by our model.     

The ripple phase in a DMPC-water mixture. A dielectric investigation

Abstract

The dielectric behaviour of a DMPC-water mixture has been investigated in the frequency range from 1 kHz to 10 MHz and in the temperature interval from 0 to 40°C over the crystalline-liquid crystalline phase transition temperatures. A model to explain the dielectric characteristics of the DMPC-water mixture as a function of frequency, and in general for each DPL-water mixture which displays a ripple phase, is proposed. The model is based on the assumption that a particular contribution to the total polarizability comes from the ripple deformation of the bilayer. This contribution is evaluated supposing strong interactions between the lipid head groups with the formation of in-phase domains of correlated electric dipoles. A further assumption relates the extension of the domains to a set of spatial modes, called ripplons, thermally activated in the ripple phase. By the ripplon dispersion relation, the dipole domain extensions (hence the polarizability), were made frequency dependent. The final result shows that the anomalous peak which appears in the permittivity at the ripple phase temperature interval is qualitatively well fitted by our model.     

Dynamic mixture probabilistic PCA classifier modeling and application for fault classification

A dynamic classifier based on the mixture probabilistic principal component analyzer (MPPCA) is proposed for fault classification. Compared with traditional methods, both fault detection and diagnosis are combined into a single classification task. By introducing a state indicator, the conventional MPPCA model is first designed as a standard classifier. Then, the static MPPCA model based classifier is temporally extended to the dynamic form within the hidden Markov model framework. Both static and dynamic MPPCA classifiers are obtained by using the Expectation‐Maximization algorithm. For performance evaluation, case studies of the continuous stirred tank heater process and the Tennessee Eastman process are carried out. Results indicate that the dynamic MPPCA classifier performs better compared with the static MPPCA classifier and the hidden Markov model based classifier. Copyright © 2015 John Wiley & Sons, Ltd.     

Colloidal rings in a liquid mixture

We investigate the self-assembly of colloidal particles on microscopic decane droplets in water and show that, by use of paramagnetic colloids, it is possible to assemble ringlike structures that can be controlled with a magnetic field. Moreover, the use of paramagnetic colloids allows us to determine the attractive forces between the colloids located at the three-phase contact line between decane, water, and air. The attractive force is in the femtonewton range and is attributed to capillary interactions due to interface deformations. When the liquid emulsion dries on a glass slide, we observe solid deposits in the form of microscopic rings of varying diameters.     

Solubility of water in a benzene-cyclohexane mixture

The solubility of a water molecule in a binary mixture of nonpolar cyclohexane and quadrupolar benzene is studied with the ab initio method. A novel self-consistent reaction field theory that properly accounts for benzene quadrupole moments in the continuum solvent framework is used to describe the solvation effects of the solvent mixture. The free energy of transfer from pure cyclohexane to the mixture solvent is obtained with the neglect of nonelectrostatic contributions. A reasonable agreement with experiments indicates that the theoretical method presented here provides a promising approach to electronic structure calculations in quadrupolar solvents and their mixtures with nonpolar solvents.     

Identification of the individual polychlorinated biphenyls in a mixture by gas-liquid chromatography.

Retention indices were computed for all of the 210 possible chlorinated biphenyls on 13 gas chromatographic liquid phases. All possible pairwise comparisons of retention indices were made for each liquid phase, each pair of liquid phases and each set of three liquid phases. On the basis of a closeness criterion of 10 (deltaRI = RIa - RIb = 10), those combinations of three or fewer liquid phases which could distinguish between nearly all possible pairs of chlorinated biphenyls were selected. Further considerations such as column efficiencies, analysis time required, resolution achievable and availability led to the selection of several common liquid phases for the qualitative and, in some cases, quantitative analysis of the individual components of mixtures of polychlorinated biphenyls. A few specific applications are discussed.     

Ultrafiltration of a polymer-electrolyte mixture

We present a mathematical model to describe the ultrafiltration behaviour of polymer-electrolyte mixtures. The model combines the proper thermodynamic forces (pressure, chemical potential and electrical potential differences) with multicomponent diffusion theory. The model is verified with experimental data on the ultrafiltration of aqueous solutions of PEG-4000 and potassium phosphate. The single solute rejection of PEG-4000 goes through a maximum as also found by others. The single solute rejection of potassium phosphate depends on the ionic strength of the solution. At low ionic strength rejections are found of 50%. Solutions containing a high concentration of PEG-4000 and potassium phosphate show a negative rejection for potassium phosphate. This is caused by the strongly non-ideal behaviour of these aqueous solutions. The model predicts the behaviour of single solute experiments quite well, but some deviations are found with the mixed solute experiments. However, negative rejections found in the mixed solute experiments are predicted by the model.     

The application of elemental analysis to the determination of the composition of a mixture of pyridine compounds

The composition of a gross mixture of pyridine compounds was determined rapidly and inexpensively by the use of standard microanalytical techniques. Spectral data corroborated the elemental results.     

Topological differences in the interaction of human DNA topoisomerase I with DNA-histone complexes modified by cis- and trans-DDP

We show that the trefoil, figure-eight knot, and mini circular closed DNA are formed by the reaction of cis-DDP-modified psiX174DNA-histone(LNCaP) complexes as a new nucleosome model with human DNA topoisomease I. The yields from cis-DDP-modified complexes were far higher than that of trans-DDP. The topologically-distinct invariant DNA such as the trefoil and figure-eight knot are not produced in the reaction of DNA topo I with psiX174DNA-histone(LNCaP) complexes that are not modified by platinum. Therefore, the anti-cancer activity of cis-DDP may be related to the production of the trefoil, figure-eight knot, and mini circular closed DNA forms in the living cell. We subsequently demonstrate that the yield mechanism and identification of the topologically-distinct invariant DNA can be explained by the topological method using a Jones polynomial and recombination through the topo I path intra-twisted looped DNA model. These results suggest that the distinguishing of anti-neoplastic activity of cis- and trans-DDP can be partially explained by the distinct topologies of DNA, trefoil, figure-eight knot, and mini circular closed DNA that they produce.     

Determination of hydrogen sulphide and sulphur dioxide in a mixture

A method has been proposed for the determination of hydrogen sulphide and sulphur dioxide in a mixture. The method is based upon the quantitative oxidation of sulphide and sulphite with an excess of radiochloramine-T in alkaline medium /0.1N NaOH/. The released chloride activity is proportional to the total amount of sulphide and sulphite present. Addition of 1% CdSO₄ solution to the mixture of sulphide and sulphite precipitates sulphide, and sulphite in the filtrate determined by the reagent. From the difference in activities, the amount of sulphide can be calculated. This method can be employed for the determination of hydrogen sulphide and sulphur dioxide in air samples.