Feedback shift register sequences versus uniformly distributed random sequences for correlation chromatography

Two alternative input sequences are commonly employed in correlation chromatography (CC). They are sequences derived according to the algorithm of the feedback shift register (i.e., pseudo random binary sequences (PRBS)) and sequences derived by using the uniform random binary sequences (URBS). These two sequences are compared. By applying the "cleaning" data processing technique to the correlograms that result from these sequences, we show that when the PRBS is used the S/N of the correlogram is much higher than the one resulting from using URBS.     

提高芯片毛细管电泳系统检测信噪比的哈达玛变换法

采用门控进样,在简单的十字通道微流控玻璃芯片上实现了假随机多次进样,研究了利用哈达玛变换提高微流控毛细管电泳分析系统信噪比的方法.在实验中,以7阶127步假随机二进制序列作为进样模板,将缓冲液和Cy₅衍生后的氨基酸试样交替注入到分离通道中,检测到的电泳信号经过哈达玛反变换还原使信噪比提高5倍(理论上5.6倍)的电泳谱,各组分的出峰时间、峰高和峰形均完全还原,毛细管电泳分离的采样频率不受影响.     

Correlation of gas solubilities in water and methanol at high pressure

A random—nonrandom—mixture equation for the Helmholtz energy of a fluid mixture is shown to correlate the solubility of inert and acidic gases in water and methanol quite accurately at pressures up to 300 bar. Further, the calculated Henry's law constants of the gases in water show good agreement with experimental data.The gas solubility models is a modification of our previous model. It contains three binary interaction parameters, one in the reduced density term and two in the attractive terms. When the nonrandom parameter vanishes the model reduces to the classical mixing rule. The model correlates vapour—liquid equilibria in binary and ternary hydrocarbon—methanol systems quite accurately.The results of the correlation are compared with results obtained using the classical van der Waals quadratic mixing rule. The random—nonrandom model is, in all cases, superior to the van der Waals model. Finally, a comparison of computer time consumption for the two models is given.     

基于伪随机二进制序列的阻抗谱快速重构及其在电化学能源领域的应用

阻抗谱的应用范围越来越广,其传统测试方法耗时长的问题也日益突出. 提高阻抗谱测量速度的各种尝试中,合成宽带激励信号和设计高效率估计算法被认为是最具潜力的解决方案,由于伪随机二进制序列（pseudo-random binary sequence,PRBS）具有功率谱平坦和易生成等优点,它在阻抗谱快速测试中具有独特优势. 本文综述了快速阻抗谱测试中三个核心问题：PRBS信号类型、不同快速算法及其在电化学能源领域的典型应用. 对于PRBS信号类型,即最大长度序列信号、混合PRBS、离散区间二进制序列和正交PRBS,本文讨论了它们各自的特点和应用范围;对于不同的PRBS激励信号的快速算法,即离散傅里叶变换/快速傅里叶变换、小波变换、快速m序列变换、基于系统辨识的参数估计算法以及这些算法各自的特点和应用范围,本文进行了深入的分析;对于PRBS阻抗谱快速测量的应用,本文以铅酸电池、锂离子电池、质子交换膜燃料电池和超级电容器等电化学能源为例,验证了其应用的可行性. 为促进技术的进一步完善,本文总结和分析了PRBS阻抗谱快速测量存在的挑战,并提出了克服这些挑战所必需的未来研究方略.     

Effect of molecular structure on the phase behaviour of some liquid crystalline compounds and their mixtures VIII. Quaternary mixtures of enantiotropes

Transition temperatures of quaternary mixtures prepared from the cyano and nitro derivatives of the two series, 4-hexadecyloxyphenyl 4-substituted benzoates (Ia,b) and 4-substituted phenyl 4-hexadecyloxy benzoates (IIa,b) have been determined by DSC and the transitions identified with polarized light microscopy. The cyano and nitro derivatives, in both series, were used because their molecules are enantiotropic. The method described before for the ternary system was extended to elucidate the eutectic composition of the quaternary system from the knowledge of either the eutectic compositions of the four possible ternary mixtures or of those of the six individual binary systems. A general equation was deduced to calculate the eutectic composition of any multi-component system from values determined for their individual binary systems. T_c values of binary, ternary, or quaternary mixtures were related to the polarizability anisotropy, Deltaalpha_X, of the individual C_Ar-X bonds. The mixture law was successfully applied.     

Modeling the effect of compatibilizers in the coarsening of ternary polymer blends with core‐shell morphology

Numerical simulations of the phase separation and coarsening of particulate, ternary polymer blends have been performed using a ternary form of the modified Cahn–Hilliard equation. The third component was chosen to be a compatibilizer, typically being a random copolymer of the major components. The results show that compatibilized blends follow the same Lifshitz–Slyozov coarsening law as binary systems. Slower coarsening rates, indicating system stabilization, were observed for blends containing ∼10% compatibilizer and exhibiting a core‐shell morphology. Larger amounts of compatibilizer resulted in significantly higher coarsening rates. This appears to be a result of the greater affinity of the compatibilizer for the major component and warrants further experimental investigation. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1301–1306, 2000     

Polymerization of coordinated monomers. XVIII. Sequence distribution in methyl acrylate–styrene copolymers prepared in the presence of zinc chloride

Methyl acrylate and styrene have been copolymerized in the presence of zinc chloride either by photoinitiation or spontaneously. The copolymerization mechanism is investigated by analyses of copolymers composition and monomer sequence distribution. The resulting copolymers are not always alternating, their composition being dependent especially on the monomer feed ratio. Appreciable deviation to higher methyl acrylate unit content from an equimolar composition occurs at monomer feed fractions of methyl acrylate over 0.7. The larger deviation is induced by higher temperature, by photoirradiation, and by greater dilution of the reaction mixture with toluene. The ¹³C-NMR spectrum of the alternating copolymer shows a sharp singlet at the carbonyl region, whereas the spectra of random copolymers prepared by benzoyl peroxide initiation at 60°C show a triplet splitting at the carbonyl carbon region, irrespective of copolymer composition. The relative intensities of the triplet peaks for the random copolymers are in good correspondence to the contents of triad sequences calculated by means of conventional radical copolymerization theory. These results clearly indicate that the carbonyl splitting is caused predominantly by variation of the monomer sequence and not by variation of the stereosequence. The monomer sequence distribution in the copolymers is thus directly and quantitatively measured from the split carbonyl resonance. Although the same triplet splitting appears in the spectra of methyl acrylate–rich copolymers prepared in the presence of zinc chloride at high feed ratios (>0.7) of methyl acrylate, the relative intensities of the split peaks do not fit the sequence distributions of random copolymers calculated by means of the Lewis–Mayo equation. The copolymerization yielding these peculiar sequences and the alternating sequence in the presence of zinc chloride is fully comprehended by a copolymerization mechanism proceeding between two active coordinated monomers, i.e., the ternary molecular complex composed of zinc chloride, methyl methacrylate, and styrene, and the binary molecular complex composed of zinc chloride and methyl methacrylate.     

Effect of molecular structure on the phase behaviour of some liquid crystalline compounds and their mixtures VIII. Quaternary mixtures of enantiotropes

Transition temperatures of quaternary mixtures prepared from the cyano and nitro derivatives of the two series, 4-hexadecyloxyphenyl 4-substituted benzoates (Ia,b) and 4-substituted phenyl 4-hexadecyloxy benzoates (IIa,b) have been determined by DSC and the transitions identified with polarized light microscopy. The cyano and nitro derivatives, in both series, were used because their molecules are enantiotropic. The method described before for the ternary system was extended to elucidate the eutectic composition of the quaternary system from the knowledge of either the eutectic compositions of the four possible ternary mixtures or of those of the six individual binary systems. A general equation was deduced to calculate the eutectic composition of any multi-component system from values determined for their individual binary systems. T_c values of binary, ternary, or quaternary mixtures were related to the polarizability anisotropy, Deltaalpha_X, of the individual C_Ar-X bonds. The mixture law was successfully applied.     

Rheological properties of ground tyre rubber based thermoplastic elastomeric blends

This work analyses the rheological behaviour of thermoplastic elastomeric blends (TPE) based on ground tyre rubber (GTR), more specifically the rheological behaviour of binary and ternary polypropylene (PP) based blends with different rubber materials: an ethylene propylene diene monomer (EPDM), an ethylene propylene rubber (EPR) and GTR. The study was developed under steady-shear rate conditions by capillary rheometry at three different temperatures. Time–Temperature Superposition Principle (TTSP) was applied to the viscosity curves using a temperature dependent shift factor, allowing the construction of master curves for the analysed blends. The Cross-WLF model was used to predict the rheological parameters, giving numerical results for viscosity similar to the experimental data. GTR increased the blends viscosity. EPR showed rheological behaviour similar to PP, and EPDM presented higher power law behaviour. Pseudoplastic behaviour was observed for all the analysed blends. Incorporation of GTR in TPE blends for injection moulding purposes was found to be a feasible strategy to upcycle this type of potentially wasted material.     

Comparison of PVDF/MWNT,PMMA/MWNT,and PVDF/PMMA/MWNT nanocomposites: MWNT dispersibility and thermal and rheological properties

Pristine multi-walled carbon nanotubes (MWNTs) were incorporated into poly(vinylidene fluoride) (PVDF), poly(methyl methacrylate) (PMMA), and PVDF/PMMA blends to achieve binary and ternary nanocomposites. MWNTs were more compatible with the PVDF matrix than with the PMMA-containing matrices. MWNT addition did not alter the development of α-form PVDF crystals in the binary/ternary composites. Nucleation and overall isothermal crystallization of PVDF were enhanced by the presence of MWNTs, and enhancements were optimal in the PVDF/MWNT binary composites. Avrami analysis revealed that addition of MWNTs led to more extensive athermal-type nucleation of PVDF, and that PMMA slightly decreased the crystal growth dimension of PVDF. The equilibrium melting temperature (T_m°) of PVDF increased in the binary composites but remained nearly constant in the ternary system. Thermal stability was enhanced in the binary/ternary composites, and enhancements were more evident in the air environment than in nitrogen. Rheological property measurements revealed that the intensely entangled chains of high-molecular weight PVDF dominated the rheological response of PVDF-included samples in the melt state. A (pseudo)network structure was developed in each of the PVDF-included samples as well as in the 1 phr MWNT-added PMMA/MWNT composite. The storage moduli of the PVDF, PMMA, and PVDF/PMMA:1/1 blend increased to 37%, 22% and 34%, respectively, at 40 °C after addition of 1 phr MWNT.     

Thermal diffusion in Lennard–Jones fluids in the frame of the law of the corresponding states

This work is related to the definition of a reduced thermal diffusion coefficient thanks to numerical microscale molecular dynamics simulations. This cross transport process, also called Soret effect, couples mass flux and thermal gradient and is still largely misunderstood. For this study, we have applied a boundary driven non-equilibrium molecular dynamics algorithm on Lennard–Jones spheres mixtures. Simulations have been performed at a constant reduced supercritical state, using a van der Waals’ one fluid approximation in order to fulfil the law of the corresponding states. In binary mixtures, we have studied the molecular parameters and the molar fraction influences on thermal diffusion separately and then combined. It is shown that, on pressure and on thermal conductivity, the corresponding states law is fulfilled for a wide range of molecular parameters ratios. In this frame, we have then constructed simple correlations which relate thermal diffusion factor to the mixture parameters. Combining the relations obtained, a reduced thermal diffusion factor taking into account all the various contributions has been defined. Finally, it is shown that this relation enables us to estimate thermal diffusion in various binary and ternary mixtures of Lennard–Jones spheres representing alkanes with a maximum deviation of 15%.     

Diphasic Domains Approach Method (DDAM)

If someone wants to plot an isobaric temperature-composition binary or an isobarothermal section of a ternary equilibria phase diagram he only needs to plot the limits of diphasic domains, it automatically gives the limits of the monophasic and triphasic fields. In such diagrams each diphasic domain is defined by two lines joining all the extremities of the tie-lines of the domain and limited by the first and the last one. These tie-lines are segments whose the extremities are in the plane of the diagram and can easily be determined by equilibria calculation codes. Then binary or ternary phase diagrams can be plotted only using conodes of the diphasic fields and the method used to determine the diphasic domains becomes the main point in binary and ternary phase diagrams plotting. A meshing of the surface of the diagram is certainly not the best way to obtain a rapid result. We propose an approach which consists to follow the curvature of the diphasic domains limits, the ‘Diphasic Domains Approach Method, DDAM’, which allows a rapid and robust determination of binary and ternary diagrams.     

The stability of ethanol in stored blood. II. The mechanism of ethanol oxidation

A new method for the i.r. analysis of zinc-dialkyldithiocarbamate mixtures has been developed. The identification and detection limits were improved, compared to the standard method, by the use of microtechniques (identification limit 2 μg, detection limit 30–80 μg). Binary and ternary mixtures can be analysed without preliminary separation, because the other components of the mixtures have very little influence on the measured absorption band. Beer's law was obeyed for the binary and two ternary mixtures. The relative standard deviations and the coefficients of correlation were calculated for the macro- and micromethods. A comparison of statistical data shows that i.r. spectroscopy is suitable for quantitative analysis even in the region of 80–10 μg of substance.     

Structural insights into the coordination and extraction of Pb(II) by disulfonamide ligands derived from o-phenylenediamine

The o-phenylenediamine-derived disulfonamide ligands 1 and 2 complex and efficiently extract Pb(II) from water into 1,2-dichloroethane via ion-exchange, in combination with 2,2'-bipyridine (97.5% and 95.0%, respectively, for 1:1 ligand-to-Pb ratios). The corresponding Pb(II)-sulfonamido binary complexes of ligands 1 and 2 (3 and 4, respectively), and ternary complexes with 2,2'-bipyridine (5 and 6, respectively), were isolated and characterized. (1)H NMR spectra of the organic phases after extraction show the formation of ternary Pb-sulfonamido-bipy complexes. X-ray characterization of 3, 4, and the ternary complex 5 consistently demonstrates four primary coordination sites and a stereochemically active lone pair on Pb. The X-ray structure of 3 shows a pseudo trigonal bipyramidal configuration on Pb, with the lone pair occupying one of the equatorial sites, and the formation of an unusual "hemidirected" coordination polymer via axial S=O-Pb coordination. The same axial S=O-Pb coordination pattern with two DMSO molecules is observed in the structure of 4.[2(CH(3))(2)SO)], thus rationalizing the high solubility of the binary complexes in strongly coordinating solvents. In contrast, the X-ray structure of the ternary complex 5 reveals a distorted four-coordinate configuration with only weak S=O-Pb coordination leading to dimer formation, thus explaining its higher solubility in weakly coordinating solvents. FT-IR spectroscopy confirms the X-ray data, since the ligand nu(S)(=)(O) stretching frequencies shift to lower values in the binary Pb(II)-sulfonamido complexes and are again altered upon formation of the ternary Pb(II)-sulfonamido-bipy complexes, as would be expected for 2,2'-bipy complexation and hindered S=O-Pb coordination.     

Vapor–liquid equilibria in the ternary system isobutyl alcohol + isobutyl acetate + butyl propionate and the binary systems isobutyl alcohol + butyl propionate,isobutyl acetate + butyl propionate at 101.3 kPa

Consistent vapor–liquid equilibrium (VLE) data at 101.3 kPa have been determined for the ternary system isobutyl alcohol (IBA) + isobutyl acetate (IBAc) + butyl propionate (BUP) and two constituent binary systems: IBA + BUP and IBAc + BUP. The IBA + BUP system show lightly positive deviation from Raoult's law and IBAc + BUP system exhibits no deviation from ideal behaviour. The activity coefficients of the solutions were correlated with its composition by the Wilson, NRTL, UNIQUAC models. The ternary system is very well predicted from binary interaction parameters. BUP eliminates the IBA–IBAc binary azeotrope. The change of phase equilibria behaviour is significant therefore this solvent seems to be an effective agent for that azeotrope mixture separation. In fact, the mean relative volatility on a solvent free basis is 1.8.The binary VLE data measured in the present study passed the thermodynamic consistency test of Fredenslund et al. [A. Fredenslund, J. Gmehling, P. Rasmussen, Vapor–Liquid Equilibria Using UNIFAC, A Group Contribution Method, Elsevier, Amsterdam, 1977], and were correlated by the Wilson, NRTL and UNIQUAC models to relate activity coefficients with mole fractions. The VLE data obtained for the ternary system passed both the Wisniak L–W [J. Wisniak, Ind. Eng. Chem. Res. 32 (1993) 1531–1533] and McDermott–Ellis [C. McDermott, S.R. Ellis, Chem. Eng. Sci. 20 (1965) 293–296] consistency test. The parameters obtained from binary data were utilized directly to predict the phase behaviour of the ternary system. The results showed an excellent agreement with experimental values.     

High-performance liquid chromatography of ternary nickel dithiocarbamate complexes derived from some sympathomimetic drugs

Summary Nickel dithiocarbamate complexes derived from some sympathomimetic drugs are examined on silica Radial-Pak columns using binary solvents containing a small percentage of an organic polar modifier. Both the type and concentration of this modifier was found to influence the separation of the ternary from the parent binary complexes. When the two ligands in a ternary complex are racemic to each other, separation of the ternary complex is only possible when certain structural requirements of the molecule are fulfilled. Ternary complexes which contain structurally similar, but nonracemic ligands, are shown to be readily separated from binary complexes. When two such complexes differ only in that one of the ligands in one is enantiomeric to a ligand in the second complex, then it can be shown that the ternary complex with the (+) enantiomer ligand elutes faster from the silica column than the one with the (–) enantiomer ligand. An example of the use of ternary complexes for the identification of optical and structurally related impurities in pharmaceutical products is also given.     

Adsorption of Sulfur Dioxide from Pseudo Binary Mixtures on Hydrophobic Zeolites: Modeling of the Breakthrough Curves

The adsorption of SO₂ from pseudo binary mixtures with water and CO₂ on hydrophobic zeolites (MFI and MOR type) was investigated using the breakthrough curve method. The SO₂ and water breakthrough curves were compared with theoretical ones based on an axially dispersed plug flow through the column and the linear driving force rate equation. In addition, different semi-predictive multi-component equilibrium equations were used for the breakthrough modeling: Langmuir 1, Langmuir 2 and Langmuir-Freundlich extended models. The overall mass transfer coefficients were derived by matching theoretical with experimental breakthrough curves for single component systems, i.e., water vapor or SO₂ in a carrier gas. They were also predicted from a simplified bi-porous adsorbent model and compared with experimentally derived values. The presence of CO₂ species in ternary mixtures with water vapor and SO₂, even at relatively high concentrations of 9 vol%, had no significant effect on the breakthrough behavior of the other two species. For that reason the CO₂ species was ignored in the analysis of the resulting pseudo binary mixtures. The breakthrough model was solved by finite element orthogonal collocation method using the commercial software gPROMS. Both extended Langmuir 1 and Langmuir 2 based models gave reasonable predictions of the water and SO₂ breakthrough curves for pseudo binary mixtures involving a mordenite sample for all water concentration levels used in this study (up to 3.5 vol%). However, the same models were successfully used to predict SO₂ breakthrough curves for a MFI sample only at low water concentrations, i.e., 1.5 vol%. At the higher water levels both models failed to describe equilibrium behavior in the MFI sample due to the introduction of multi-layer adsorption in the interstices between small MFI-26 crystals.     

Phase equilibria in the ternary system isobutyl alcohol + isobutyl acetate + 1-hexanol and the binary systems isobutyl alcohol + 1-hexanol,isobutyl acetate + 1-hexanol at 101.3 kPa

Consistent vapor–liquid equilibrium (VLE) data at 101.3 kPa have been determined for the ternary system isobutyl alcohol (IBA) + isobutyl acetate (IBAc) + 1-hexanol and two constituent binary systems: IBA + 1-hexanol and IBAc + 1-hexanol. The IBA + 1-hexanol system exhibits no deviation from ideal behaviour and IBAc + 1-hexanol system show lightly positive deviation from Raoult's law. The activity coefficients of the solutions were correlated with its composition by the Wilson, NRTL, UNIQUAC models. The ternary system is well predicted from binary interaction parameters. 1-Hexanol eliminates the IBA–IBAc binary azeotrope. However, the change of phase equilibria behaviour is small therefore this solvent is not an effective agent for that azeotrope mixture separation. In fact, the mean relative volatility on a solvent free basis is 1.28 (close to unity).     

Conductivity and structure of melt‐processed polyaniline binary and ternary blends

In the present study, conductive binary and ternary blends containing polyaniline (PANI) were developed through melt blending. The binary blends' investigation focused on the morphology, in light of the components' interaction, and the resulting electrical conductivity. Similar solubility parameters of a given doped PANI and a matrix polymer lead to dispersion of fine PANI particles within the matrix, and to formation of conducting paths at low PANI contents. A plasticizer acting also as a compatibilizer improves the matrix polymer/PANI interactions. In ternary blends consisting of PANI and two immiscible polymers, the PANI preferrentially locates in one of the components, affecting the blend's morphology. This “concentrating” effect leads to relatively high electrical conductivity at a low PANI content. The electrical conductivity of the studied ternary blends is almost independent of the components' sequence of addition into the hot melt mixing device, exhibiting the selectivity of PANI towards one of the components. Copyright © 2000 John Wiley & Sons, Ltd.     

Calculating binary and ternary multiphase equilibria: extensions of the integral area method

The area method was proposed in 1992 to calculate binary and ternary 2-phase equilibria. In its integral form, the method provides both the necessary and sufficient conditions required for the determination of the global minimum reduced Gibbs energy of mixing (Φ). The method has since been applied to the calculation of both pure component and ternary multiphase equilibria in a differential form. However, the extension of the original (2 point) integral area method to the direct calculation of both binary and ternary multiphase equilibria has not been completed. Direct 3 point and modified 2 point search methods have therefore been developed here and used to estimate the phase compositions of a representative binary vapour-liquid-liquid system. The 2 point area method principle has been extended and applied to the calculation of ternary multiphase equilibria using a net volume approach. However, this volume method was found to fail due to an underlying inconsistency in the bounding of the integrated Φ surface by the trial 3-phase region. A new method is proposed that overcomes this problem by minimising the area of intersection between a tangent plane and the Φ surface. This new method has successfully calculated the 3-phase compositions of two simple test systems from a variety of initial mixture starting points.