Characterization of the molecular weight distribution of isotactic polypropylene by turbidity at the lower critical solution temperature (LCST)

The molecular weight distribution (MWD) of high-molecular-weight isotactic polypropylene is measured by a new method developed for polyethylene (PE) using the turbidity at the lower critical solution temperature (LCST). The attenuation of transmitted light h_i is measured at T_i as each fraction i is separated from the solution during a temperature increase ΔT_i. From the thermogram, the set of h_i (T_i), the MWD can be calculated through a relation M_i = f(T_i). The solvent chosen, a mixture of butane and 2-methylbutane, optimizes resolution and relatively rapid dissolution. Homogenization and absence of degradation are verified by different methods including calorimetry in solution. © 1992 John Wiley & Sons, Inc.     

Antibody-based surfaces: rapid characterization using two complementary colorimetric assays

Finding a general solution for optimizing the grafting of antibody on solid surfaces is difficult due to the variety of material, grafting principles and chemistries or surface formats available (beads, microplates, fibers, etc.). Pre-screening methods able to assess grafting efficiency (GE) and specific activity (SA) are required. In this context, we present here two colorimetric assays that can be used on a wide variety of surface format, chemistry, etc. The first one, ADECA (Amino Density Estimation by Colorimetric Assay) allows a rapid estimation of grafted antibodies and allows calculating the GE. The second one, A₂HRP (Antibody Anti-HorseRadish Peroxidase) provides a measure of the amount of active antibody, which, combined to ADECA, is used to determine the SA of grafted antibody. Analytical parameters (limit of detection, repeatability, linearity, etc.) of these two colorimetric assays are presented. Using two commercially available microplates, we demonstrated that, when used in parallel, these rapid and sensitive methods are well adapted to pre-screening of antibody grafting performances.     

Comparative Thermodynamic Analysis of Ga-GeSb0.855 Section in the Ternary System Ga-Ge-Sb

Thermodynamic investigations of Ga-GeSb_0.855 section in the ternary system Ga-Ge-Sb, which is of a practical importance in electric-industry, are presented in this paper. Results of a comparative thermodynamic analysis at 1273 K obtained by Oelsen calorimetry and predicting methods - general solution model and Hajra's method are also given. This revised version was published online in August 2006 with corrections to the Cover Date.     

Prediction of ternary excess enthalpy data by the UNIFAC Group Contribution method

The UNIFAC Group Contribution method is applied to predict ternary excess enthalpies H ^E . In order to improve previous predictions, values for the group interaction parameters are determined from binary excess enthalpy data. These parameters are used to estimate sixty-four sets of ternary H ^E data which are compared with data from the literature. Results are also compared with those obtained using methods to predict ternary excess enthalpies from the binary H ^E data for the three binary system involved.Communicated at the Festsymposium celebrating Dr. Henry V. Kehiaian's 60^th birthday, Clermont-Ferrand, France, 17–18 May 1990.     

Prediction of miscibility regions in ternary blends of poly(styrene-stat-acrylonitrile), poly(acrylonitrile-stat-methyl methacrylate), and poly(styrene-stat-methyl methacrylate)

The miscibilities of ternary copolymer blends prepared from poly(styrene-stat-acrylonitrile), poly(styrene-stat-methyl methacrylate), and poly(methyl methacrylate-stat-acrylonitrile) were predicted by calculating the interaction parameter, χ_blend, for various blend combinations, from the corresponding binary segmental interaction parameters estimated from previous work. Binodal and spinodal curves were calculated using the Flory-Huggins theory and it was observed that the most accurate estimate of the boundary between miscible and immiscible blends was given by the spinodal. It has also been demonstrated that in some of the ternary blends with fixed copolymer compositions the miscibility of the blend can be altered by changing the ratio of the three components in the mixture. Conditions for miscibility in this ternary system, and possibly a general feature of all such systems, are (a) that at least two of the binary interaction parameters χ_ij are less than the critical value χ_crit, while the third should not be too much larger, that is, one of the copolymers may act as a compatibilizer for the other two copolymers, (b) that the difference Δχ = /χ₁₂ ? χ₁₃/ is small. © 1992 John Wiley & Sons, Inc.     

Equilibrium studies on some heteroligand hydroxo complexes of lanthanons with iminodiacetic acid and citraconic or maleic acid

Mixed-ligand ternary complexes of La(III), Pr(III), Nd(III), Gd(III), and Dy(III) with iminodiacetic acid (IMDA) and citraconic (CCA) or maleic acid (MIA), have been studiedpH-metrically. Their formation takes place through the stepwise addition of the secondary ligand (IMDA) to the initially formed 1:1, Ln(III)—CCA/MIA binary species. The resulting ternary complexes undergo hydrolysis to form their hydroxo derivatives simultaneously. The stability constants of the hydroxo species are calculated for constant temperature (27 ± 1°C) and ionic strength (I=0.1M KNO₃). The relative order of stability is: La(III)

Gleichgewichtsuntersuchungen an einigen Heteroliganden-Hydroxo-Komplexen von Lanthanid-Ionen mit Iminodiessigsäure und Citracon- oder Maleinsäure

Zusammenfassung Es wurden ternäre Komplexe von La(III), Pr(III), Nd(III), Gd(III) und Dy(III) mit gemischten Liganden [Iminodiessigsäure (IMDA) und Citraconsäure (CCA) oder Maleinsäure (MIA)] mittelspH-metrischer Methoden untersucht. Diese Komplexe werden über die stufenweise Addition des Sekundärliganden (IMDA) zu den primär gebildeten 1:1 Ln(III)—CCA/MIA Spezies gebildet. Zugleich erleiden die resultierenden ternären Komplexe Hydrolyse und gehen in die entsprechenden Hydroxo-Komplexe über. Die Stabilitätskonstanten der Hydroxo-Komplexe wurden für konstante Temperatur (27 ± 1°C) und Ionenstärke (I=0.1M KNO₃) berechnet. Die relative Reihung bezüglich der Stabilitäten ergab sich folgendermaßen: La(III)     

Potentiostatic voltammetry at spherical electrodes and microelectrodes in the presence of product

An explicit analytical solution for the complete anodic–cathodic I–E–t response of a reversible electrode process in presence/absence of amalgamation under potentiostatic conditions is presented. To obtain this solution we have taken into account the electrode curvature, using in the case of amalgamation, Koutecký’s approximation (i.e. the finite electrode volume has not been considered). Explicit expressions for the concentration profiles and the surface concentrations have been also deduced. All the results are applicable to electrodes of any radius including ultramicroelectrodes when both species are soluble in the electrolytic solution for any value of the ratio D_O/D_R. When amalgamation takes place, analytical results were compared with the numerical ones deduced by using the rigorous condition of null net flux in the electrode centre, pointing out that Koutecký’s approximation remains valid even for electrode radius and time values at which the diffusion layer reaches the electrode centre. For high electrode sphericities the I–t curves present a cross-linking for applied potential values higher than the equilibrium potential which is the cause of the appearance of a “peak” near to the anodic limit of the I–E curve.     

Evaluation of statistical control charts for on-line radiation monitoring

Statistical control charts are presented for the evaluation of time series radiation counter data from flow cells used for monitoring of low levels of ⁹⁹TcO₄⁻ in environmental solutions. Control chart methods consisted of the 3-sigma (3σ) chart, the cumulative sum (CUSUM) chart, and the exponentially weighted moving average (EWMA) chart. Each method involves a control limit based on the detector background which constitutes the detection limit. Both the CUSUM and EWMA charts are suitable to detect and estimate sample concentration requiring less solution volume than when using a 3σ control chart. Data presented here indicate that the overall accuracy and precision of the CUSUM method is the best.     

Hypersensitivity and its application to structural analysis of lanthanide complexes

Hypersensitivity of the ternary complexes Ln(β-dik)4HMQ(where Ln=Nd, Ho, Er,β-dik=acetylacetonate(AA), dibenzoylmethanate(DBM) and MQ=4-methylquinoline) in acetone solution is studied based on the dynamic coupling model. The structures of these complexes in solution are deduced. Their coordination polyhedrons are all distorted square antiprism. Neodymium complexes have D2 symmetry, while holmium and erbium complexes have exact D2d symmetry.     

Preparation and Thermal Chemical Property of Complexes of Zinc Nitrate with Trytophan

IntroductionZincisanessentialtraceelementtothelife .Manydiseasesarousedfromadeficiencyofzincelementhavere ceivedconsiderableattention .L α Aminoacidsarebasicunitsofproteins .L α Trytophanisoneoftheeightspeciesofaminoacidsindispensableforlife ,whichhastobeab sorbedfromfoodbecauseitcannotbesynthesizedinthehumanbody .InviewofthecomplexesofL α trytophanandessentialelementsasaddictiveswidelyusedinsuchfieldsasfoodstuff,medicineandcosmetic ,1 3theyhaveabroadenprospectforapplications .Briefly ,ab…     

Thermochemical investigations of the systems KCl−KBr−H2O,K2SO4−(NH4)2SO4−H2O and KNO3−NH4NO3−H2O at 298.15 K

For the equilibrium solid phases occurring in the systems: KCl?KBr?H₂O, K₂SO₄?(NH₄)₂SO₄?H₂O and KNO₃?NH₄NO₃?H₂O, the concentration dependencies of differential solution enthalpies, Δ_sol H ₂ for several crystallization paths, were measured. The limiting differential solution enthalpies, Δ_sol H ₂ ⁰ , were determined by extrapolation of the above dependencies to the ionic strength,I _m ⁰ , corresponding to the appropriate binary solutions. For KCl?KBr?H₂O system only, the clear dependence between Δ_sol H ₂ ⁰ andI _m ⁰ values was found and discussed.     

Dynamical relaxations in mixtures of different polymers and nonsymmetrical copolymers in solution

Dynamical relaxation properties of nonsymmetrical mixtures of homopolymers and of copolymers in solution are examined. In particular, examples of bimodal mixtures in solution, ternary mixtures of two different homopolymers and a solvent, and nonsymmetrical diblock copolymers in solution are examined. The frequencies of the eigenmodes Γ and Γ′, those of the cooperative mode Γ_T and the interdiffuse mode Γ_I are calculated for these systems. It is found that the variations of T_T and T_I, with the scattering wave number q are practically identical to those of Γ_T and Γ_I, respectively. This identity is rigorous only for mixtures or copolymers where the two polymer components are identical except for their contrast factors (i.e., indices of refraction or scattering lengths). Here, it is argued that the identification of the eigenmodes with the cooperative and interdiffuse modes can be extended qualitatively to mixtures of different polymers and to nonsymmetrical copolymers in solution.     

In Situ Ternary Adduct Formation of Yttrium Polyaminocarboxylates Leads to Small Molecule Capture and Activation

In this work the chemistry of yttrium complexes is exploited for small molecule capture and activation. Nuclear magnetic resonance (NMR) and density functional theory (DFT) studies were used to investigate the in situ formation of solution state ternary yttrium-acetate, yttrium-bicarbonate, and yttrium-pyruvate adducts with a range of polyaminocarboxylate chelates. These studies reveal that [Y(DO3A)(H₂O)₂] (H₃DO3A – 1,4,7,10-tetraazacyclododecane-1,4,7-tricarboxylic acid) and [Y(EDTA)(H₂O)_q]⁻ (H₄EDTA – ethylenediaminetetraacetic acid, q = 2 and 3) are able to form ternary adducts with bicarbonate and pyruvate. In the latter, unusual decarboxylation of pyruvate to form acetic acid and CO₂ was observed and further studied using SABRE-hyperpolarised ¹³C NMR (SABRE – signal amplification by reversible exchange) to provide information about the reaction timescale and lifetime of intermediates involved in this conversion. The work presented demonstrates that yttrium complexes can capture and activate small molecules, which may lead to novel and useful applications of this metal in catalysis and medical imaging.     

A Novel Solution Method for Interpreting Binary Adsorption Isotherms from Concentration Pulse Chromatography Data

Adsorption separation of carbon dioxide from nitrogen (N₂, which represents air) was investigated by using H-ZSM-5 as the adsorbent with SiO₂/Al₂O₃ ratios of 30 and 280. Pure and binary isotherms at 40°C have been determined experimentally using concentration pulse chromatography.Presently available methods for determining binary isotherms from concentration pulse chromatography data have been reviewed and shown incapable of interpreting this particular binary system. A novel solution method is presented and shown to be superior to the other methods.The binary isotherms for the CO₂-N₂ system show an increase in CO₂ selectivity with increase in surface heterogeneity. The optimal separation factor for H-ZSM-5-30 was found to be 215 at 0.7% CO₂ in the feed, whereas, H-ZSM-5-280 has an optimal separation factor of 48 at 2.7% CO₂ in the feed.     

The Al-Zn-Ga Phase Diagram Part II

The first part of this paper presented five experimental isopletic cuts in the Al-Zn-Ga ternary phase diagram. On these cuts, two isobaric ternary invariant reactions were determined and a significant retrograde miscibility of Ga in a α′_SS solid solution was observed. In the second part, the two isobaric invariant reactions are studied more precisely. In particular, the composition of the invariant phases are given and the Ga miscibility in the α_SS ternary solid solution is studied. Isothermal sections are established. The results confirm the existence of a vanishing point in the liquidus area, conjugated with a ternary critical point at about 290°C. A general perspective shape of the equilibria in the diagram is proposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sound absorption studies of ternary systems

The peak sound absorption region of ternary systems of water-2-propanolurea, water-2-propanol-tetraethylammonium bromide, water-2-propanol-1,10-bis(triethylammonium)decane dibromide, and the binary system water-2-propanol has been studied at 10, 30, and 50 MHz, and in the temperature range 1.4 to 35°C. The results from the binary system show that the peak sound absorption composition (PSAC) is shifted to higher alcohol composition and (/f ²)_max decreases with increasing temperature. At constant frequency, increased urea concentration has the same effect on PSAC and (/f ²)_max values as does an increase in temperature for the binary system. All salts decrease /f ² values at low concentrations but differ remarkably at higher concentrations. The results are interpreted qualitatively as showing the excess sound absorption in the PSAC region to be intimately related to the structural characteristics of water.     

Liquid-Liquid Equilibria for Water + Nitromethane + (1-Propanol,or + Acetone,or + p-Dioxane) Ternary Systems at 303.15 K

Abstract

Liquid-liquid equilibria, distribution coefficients, and selectivities of ternary systems of the type: (water + K + nitromethane), where Kis 1-propanol, acetone, or p-dioxane, have been determined at (303.15 ± 0.05) K, in order to evaluate the suitability of nitromethane for extracting preferentially the second components from their aqueous solutions. The line data were satisfactorily correlated by the Othmer and obias method, and the plait point coordinates for the three systems were estimated. The experimental data were compared with values calculated using the NRTL and UNIQUAC models, and with those predicted by the UNIFAC group contribution method. This last method predicts qualitative and quantitative behaviour which are in disagreement with experimental results, while the values calculated using the other two models are in agreement but only when the concentration of component K is low. The three ternary systems studied have distribution coefficients higher than unity, and high selectivities. Therefore, nitromethane could be considered as a potential solvent for the extraction of K from its aqueous solutions     

On the interpretation of solubilization results obtained from semi-equilibrium dialysis experiments

The interpretation of intramicellar solubilization data obtained from semi-equilibrium dialysis (SED) experiments is described, and methods are presented for determining equilibrium constants for the solubilization of organic species by aqueous surfactant solutions as well as activity coefficients of both the organic solute and the surfactant within the micelle. The solubilization equilibrium constant of an organic solute in an aqueous micellar solution (K) is defined as the ratio of the mole fraction of organic solute in the micellar pseudophase (X) to the concentration of the unsolubilized monomeric organic solute in the aqueous phase (c ₀). Expressions compatible with the Gibbs-Duhem equation are used to represent the concentration dependence of activity coefficients of both the solubilizate and surfactant in the micellar pseudophase; the analysis leads to calculated values of the concentrations of free and intramicellar surfactant and organic solute in both compartments of the equilibrium dialysis cell. Solubilization equilibrium constants for many amphiphiles are well correlated by the simple expressionK=K ₀(1-BX)², whereB is an empirical constant andK ₀ is the limiting value ofK asX approaches 0.     

Solution‐Based Synthesis of Layered Intergrowth Compounds of the Homologous PbmBi2nTe3n+m Series as Nanosheets

Layered intergrowth compounds in the homologous Pb_mBi_2nTe_3n+m family are interesting because they are examples of natural heterostructures. We present a simple solution‐based synthesis of two‐dimensional nanosheets of PbBi₂Te₄, Pb₂Bi₂Te₅, and PbBi₆Te₁₀ layered intergrowth compounds, which are members of the Pb_mBi_2nTe_3n+m [that is, (PbTe)_m(Bi₂Te₃)_n] homologous series. Few‐layer nanosheets exhibit narrow optical band gaps (0.25–0.7 eV) with semiconducting electronic‐transport properties.     

Influence of concentration on the activation energy for diffusion in polymer-solvent systems

The self-diffusion of benzene, toluene, and ethylbenzene in polystyrene have been analyzed using the Vrentas/Duda free-volume diffusion model. Diffusion coefficient predictions suggest an exponential concentration dependence of the activation energy required to overcome attractive forces, E. Without the use of any diffusion data approximating E as zero over the entire concentration range yields self-diffusion coefficient predictions which are in good agreement with experimental data. © 1992 John Wiley & Sons, Inc.