Five Years of Dispersive Liquid–Liquid Microextraction

Abstract: The present article offers a historical overview and a comprehensive collection of publications devoted to dispersive liquid–liquid microextraction (DLLME), including modifications made to it and techniques derived from it. The principle of DLLME is discussed, as are the detection techniques employed, their applications, and milestones in the development of DLLME. The applications and the most important parameters of dispersive liquid–liquid microextraction and related techniques are summarized in a table.     

Structural Characteristics of Liquid Sn

We investigate the structural properties of liquid Sn. With the help of the internal friction (tanФ) method, it is found that a peak appears in the tan Ф - T curve, suggesting that an anomalous discontinuous temperatureinduced structure change may take place in liquid Sn. From the experimental data of pair distribution functions, we calculate the viscosity η and the excess entropy S and it is found that there are a peak of viscosity in the η-T curve and a bend of excess entropy in the S - T curve, which give a positive support to the appearance of the internal-friction peak in the tan Ф- T curve.     

Flow Analyses of Liquid Metal First Wall

In fusion reactor design, first wall is one kind of plasma-facing components (PFCs),which will be irradiated by high energy neutrons and other particle, as well as work under high plasma heat flux. They should be considered carefully. Many experiments and     

Numerical Study of Luttinger Liquid Regime of Two-Leg Hubbard Ladders

We investigate two-leg Hubbard ladders in the Luttinger liquid regime by the density-matrix renormalization group method. Applicability of the bond concept in this region is discussed in a quantitative comparison of power-law decay exponents, energy components and anti-bond occupations between ladders and chains. The interaction between bond and anti-bond bands induced by finite Hubbard repulsion U is emphasized by our numerical results. Our quantitative results are useful for the justification of the validity of various analytical approaches.     

Stability of the Landau–Fermi Liquid Theory

The stability of the Landau–Fermi liquid theory is investigated. It has been shown that if the interaction function of the Fermi system is a finite function of the angle between the momenta of two particles at the Fermi surface, then the liquid can be stable. We have shown that the absolute value of the expansion coefficients of the interaction functions in Legendre polynomials are decreasing function of the coefficients indices. We solve the stability condition for one photon exchange (OPE) in an electron gas. The results show that we must use the massive boson propagator (higher order corrections to the photon propagator). Similar to previous works (Abrikosov et al. in Method of Quantum Field Theory in Statistical Physics, Pergamon, Elmsford, 1965), our result is proportional to g ². The density and temperature dependence of results is occulted in the effective mass of the system.     

Microscopic Theory of Blue Phases Ⅰ and Ⅱ of Liquid Crystal

The microscopic theory of the blue phases of chiral liquid crystal is proposed. Beginning with the potential between two molecules, by using the cell model of liquid, applying statistical physical method, the distribution function and the free energy of the system are obtained. By using variational approach and zero-order approximation, the differential equation that the order parameter tensor of the blue phase can satisfy is obtained. Then we change the differential equation to the eigenequation problem in quantum mechanics. Considering the symmetry of the blue phases, the order parameter tensors of blue phases Ⅰ and Ⅱ can be made up of the eigenvectors. Our results are the same as the results of Ginzberg-Landau‘s phenomenological theory. The parameters in the order parameter tensors that we calculate in the located system are close to the predecessors‘ results.     

Near-Field Birefringence Response of Liquid Crystal Molecules in Thickness Direction of Liquid Crystal Thin Film Orientated by Shear Force

Information of molecular orientation in nematic liquid crystal （LC） is attractive and important for applications in the field of display devices. We demonstrate a novel method using a birefringence scanning near-field optical microscope （Bi-SNOM） with a probe which is inserted into the LC thin film to detect the molecular orientation from its birefringence responses in the thickness direction of the LC thin film. The probe is laterally vibrated when going forward into the LC thin film, and the retardation and azimuth angle are recorded as the probe going down. Firstly, the thickness of the LC thin film is measured by the shear force detection. Since the shear force acts as a stimulation to reorientate the LC molecules above the substrate surface, we can detect the molecular orientation caused by a polyimide alignment substrate and the effect to molecular orientation caused by vibration of fibre probe. As a result, the orientation profiling of the LC film in depth direction is obtained in both the cases that the direction of probe vibrating is vertical/parallel to the rubbing direction of the alignment film. Furthermore, the thickness of completely orientated layers just above the substrate surface can also be obtained by either vibrating probe or no-vibrating probe. Ultimately, the LC thin film can be modelled in thickness direction from all the results using this method.     

A New Model for Microstructure of Liquid Metals

A nanocrystalline model for microstructures of liquid metals is constructed. According to the nanocrystalline model, the intensity curves of x-ray diffraction (XRD) on liquid Cu, A1 and Al65Cu20Fe15 alloy are derived by broadening the XRD peaks of these metals in some crystal structures. These broadening intensity curves are     

Steady States of a Plug Flow Reactor Operating on a Heterogeneous Liquid−Liquid System

A plug flow reactor operating on a heterogeneous liquid?liquid system in which an exothermic bimolecular reaction takes place is modeled. The effect of the main governing parameters (Peclet and Damkheler numbers and a dimensionless parameter P characterizing mass transfer between the liquid phases) on the thermal modes of the reactor is examined. Depending on the values of these parameters, one or three steady states can be realized in the reactor. It is established that, with increasing parameter P, the region of multiplicity of steady states expands and shift toward lower values of the Damkohler number. The phenomenon of hysteresis is observed in the region of multiplicity of steady states.     

Microscopic Theory of Blue Phases Ⅰ and Ⅱ of Liquid Crystal

The microscopic theory of the blue phases of chiral liquid crystal is proposed. Beginning with the potential between two molecules, by using the cell model of liquid, applying statistical physical method, the distribution function and the free energy of the system are obtained. By using variational approach and zero-order approximation, the differential equation that the order parameter tensor of the blue phase can satisfy is obtained. Then we change the differential equation to the eigenequation problem in quantum mechanics. Considering the symmetry of the blue phases,the order parameter tensors of blue phases Ⅰ and Ⅱ can be made up of the eigenvectors. Our results are the same as the results of Ginzberg-Landau‘s phenomenological theory. The parameters in the order parameter tensors that we calculate in the located system are close to the predecessors‘ results.     

Vortex-Assisted Liquid–Liquid Microextraction for the Determination of Residual Sulfonamides in Meat Samples with Spectrofluorophotometer

A simple and fast extraction termed vortex-assisted liquid–liquid microrextraction coupled with molecular fluorescence spectroscopy has been developed and used for the detection of three sulfonamides (sulfadiazine sodium, sulfamethoxazole, and sulfaguanidine) in the meat samples. In the vortex-assisted liquid–liquid microrextraction method, 400 µL of nonanoic acid was used as extractant and directly injected into 10 mL centrifuge tube containing a derivative, which sulfonamides derived with o-phthaladehyde. And the extraction solvent was dispersed into the water phase under mechanical force with the vortex-mix. The polar side was reduced and the strong fluorescence produced at λ_ex = 295 nm. Variable parameters affecting the derivatization and vortex-assisted liquid–liquid microrextraction procedure were evaluated and optimized. The vortex-mix substituted effect of disperser solvent in this procedure. The limits of detection were 2.0 ng mL^?1 for sulfadiazine sodium and sulfamethoxazole, 0.5 ng mL^?1 for sulfaguanidine with the relative standard deviations of the method ranging from 2.5% to 6.1%. And the calibration graph was linear from 5 to 5000 ng mL^?1 with coefficient of determinations more than 0.9995. Recoveries of the three sulfonamides on spiked meat samples at different levels were 92.2–102.5%. Finally, the method has been successfully applied to the determination of sulfonamides from meat samples.     

Resonant Response of Rectangular/kFM Cantilever in Liquid

Dynamic characteristics of atomic force microscopy （AFM） cantilevers can be influenced by their working media. We perform an experimental study on the resonant responses of rectangular AFM cantilevers with different sizes immersed in various viscous fluids. The measured resonance frequencies in liquids are used to valldate several theoretical models. Comparison shows the analytical model proposed by Sader [J. Appl. Phys. 84 （1998） 64] can give the best agreement with the experimental results with the maximum relative error nearly 16% for all the cantilevers in different liquids. The ratio between the resonant frequencies in air and water is almost independent of the cantilever length, which is consistent with the theoretical analyses.     

Liquid–Liquid Transition and Detrapping of Trapped Carriers of P(MMA/BA) Copolymers by Thermally Stimulated Depolarization Current

Poly (methyl methacrylate/butyl acrylate) [P(MMA/BA)] copolymers (M _η～2×10⁵) with different mass percentages of PMMA (100/0, 90/10, 81/19, and 75/25), were synthesized by the method of solution polymerization. In addition to the normal α and ρ peak, a third τ peak is observed in thermally stimulated depolarization current (TSDC) spectra of the copolymers in the high temperature region. The α peak‐corresponds to the glass transition, the ρ peak originates from the detrapping of trapped carriers in the bulk amorphous structure related with flexible side groups, and the τ peak can be attributed to the charge detrapping related to the liquid–liquid transition of the copolymers. The three peaks all move to lower temperature with an increase of the BA component, indicating that the flexible side groups of butyl acrylate not only have an effect of plasticization on the glass transition and liquid–liquid transition, but also make the trap depth shallower and the detrapping process easier for the ρ and τ peaks. The experimental results confirm that TSDC analysis is very sensitive for investigating the liquid–liquid transition of polymers. The liquid–liquid transition temperature (T _LL) of the copolymers follows a type of the Fox equation. Fitting the results gives a T _LL of 102°C for polybutyl acrylate.     

Equation of State of Dense Liquid Nitrogen in the Region of the Dissociative Phase Transition

We have measured the equation of state for liquid nitrogen compressed dynamically to a pressure of 10-60 GPa by employing a two-stage light-gas gun.The data show a continuous phase transition above the shock pressure of 33GPa,as indicated previously by shock wave experiments.A theoretical model has been derived to examine the experimental data by inducing a molecular dissociative fraction.According to theoretical and experimental date the phase transition was thought to be a molecular dissociative phase transition.     

Kinetics of Liquid Structure Transition of Sn-（40wt%）Bi Melt

The kinetics of temperature-induced liquid-liquid structure transition （TI-LLST） process in Sn-（40wt%）Bi melt is investigated in isothermal and continuous heating experiments with electrical resistivity method. The time evolution pattern of the electrical resistivity suggested the transition mechanism of TI-LLST for Sn-（40wt%）Bi melt in accordance with the autocatalytic reaction model, which is an indication of nucleation-growth type. With the calculated reaction rate constant KT and apparent activation energy Δ E, we deduce the reason for the characteristics of TI-LLST. The present result may be beneficial for further understanding of the nature of TI-LLST.     

Chiral Parameter of Transparent Films Containing Polymer Cholesteric Liquid Crystal-R

The transparent film containing a kind of polymer cholesteric liquid crystal-R was fabricated by the freezing method. The optical polarization response of the film was investigated by a self-manufactured apparatus and its optical rotatory dispersion was measured by a novel technique at the wavelength from 35Onto to 66Onto.At various wavelengths, the chiral parameter of the film has been obtained. The results show that the chiral parameter decreases as the wavelength increases. The maximum and minimum chiral parameters are 0.0343 at the wavelength of 350 nm and 0.0058 at the wavelength of 660 nm, respectively. The obtained data indicate that this kind of polymer cholesteric liquid crystal-R is a promising candidate host material for solid optical chiral waveguides.     

Liquid Nuclear Magnetic Resonance Implementation of Quantum Computation in Subspace

Based on the logical labelling method, we prepare an effective pure state in a subsystem of a three spin system via liquid nuclear magnetic resonance technique. Then with this subspace effective pure state we implement the Deutsch-Jozsa algorithm. The tomography for the subspace effective pure state and the corresponding spectrum of the output for the Deutsch-Jozsa algorithm agree with theoretical predictions, which shows that we have successfully implemented the Deutsch-Jozsa algorithm in a subsystem of a nuclear spin system and demonstrated a subspace quantum computation.     

Liquid–vapour equilibrium of n -alkanes using interface simulations

Molecular Dynamics simulations were performed to calculate liquid–vapour coexisting properties of n-alkane chains up to 16 carbon atoms using interface simulations. The lattice sum or Ewald method on the dispersion forces of the Lennard–Jones potential was applied to calculate the full interaction. The liquid and vapour coexisting densities were obtained for two flexible force field models, NERD and TraPPE-UA, where the intermolecular interactions are of the Lennard–Jones type. We have recently shown [P. Orea, J. López-Lemus, and J. Alejandre, J. Chem. Phys. 123, 114702 (2005)] that the liquid–vapour densities for simple fluids do not depend on interfacial area and therefore it is possible to use a small number of molecules in a simulation. We show that the same trend is found on the simulation of these hydrocarbon molecules. The phase diagram of ethane/n-decane binary mixtures is also obtained at 410.95 K for the NERD model. The simulation results from this work were compared with those obtained using methods with interfaces using large cut-off distances and with methods without interfaces for the same potential model. In both comparisons, excellent agreement was found. The results of liquid density from the TraPPE-UA model are in good agreement with experimental data while those from the NERD model are underestimated at low temperatures. Our findings are consistent with results published by other authors for small hydrocarbons.