Method for the Determination of Sudan Dyes in Foods-High Performance Liquid Chromatography Jointly Issued by AQSIQ and SAC

Sudan Red are the chem osynthesisdyesofseriesofazo,w hich are m ainly used ascoloring additives in m a-nufacturing of som e products, such as the w ax, theoil-dyes,the petrol,and etc.In the process offood pro-duction,Sudan D yesare banned to be used asfood dyesin ourcountry.In Feb. 2005, the Food Standards A gency (FSA )declared the w ithdraw alofthe foodspolluted by the Su-dan D yes. A fter that, the G eneral A dm inistration ofQ uality Supervision, Inspection and Q uarantine of thePe…     

Predictions of Phase Distribution in Liquid–Liquid Two-Component Flow

Ground-based liquid–liquid two-component flow can be used to study reduced-gravity gas-liquid two-phase flows provided that the two liquids are immiscible with similar densities. In this paper, we present a numerical study of phase distribution in liquid–liquid two-component flows using the Eulerian two-fluid model in FLUENT, together with a one-group interfacial area transport equation (IATE) that takes into account fluid particle interactions, such as coalescence and disintegration. This modeling approach is expected to dynamically capture changes in the interfacial structure. We apply the FLUENT-IATE model to a water-Therminol 59^® two-component vertical flow in a 25-mm inner diameter pipe, where the two liquids are immiscible with similar densities (3% difference at 20°C). This study covers bubbly (drop) flow and bubbly-to-slug flow transition regimes with area-averaged void (drop) fractions from 3 to 30%. Comparisons of the numerical results with the experimental data indicate that for bubbly flows, the predictions of the lateral phase distributions using the FLUENT-IATE model are generally more accurate than those using the model without the IATE. In addition, we demonstrate that the coalescence of fluid particles is dominated by wake entrainment and enhanced by increasing either the continuous or dispersed phase velocity. However, the predictions show disagreement with experimental data in some flow conditions for larger void fraction conditions, which fall into the bubbly-to-slug flow transition regime. We conjecture that additional fluid particle interaction mechanisms due to the change of flow regimes are possibly involved.     

Advances in the Experimental Determination of the Uranium–Oxygen Phase Diagram at High Temperature

Due to its complex phase diagram and the employment of UO₂ as a nuclear fuel, the binary system U–O is of great interest both scientific and technological. Numerous experimental and theoretical studies have been carried out in the last 45 years in order to determine the properties of this system, leading to a precise definition of a considerable part of the state diagram in the region ranging from pure uranium to stoichiometric UO₂, and at temperatures lower than 1500 K, up to the oxide U₄O₉. However, due to the poor chemical stability of O–U compounds with high oxygen content at high temperature (O/U > 2, T > 2000 K), an important part of the phase diagram still lacks experimental data. In this work measurements are presented on the melting transition of the stoichiometric and hyperstoichiometric dioxide UO_2+x up to x=0.21, and on the melting point of the higher oxide U₃O₈. These measurements were performed under buffer gas pressures varying between 10 and 250 MPa, using a method based on subsecond laser heating developed to overcome experimental difficulties encountered by previous researchers. Paper presented at the Seventh International Workshop on Subsecond Thermophysics October 6–8, 2004, Orléans, France.     

Segregation of Liquid Phase in the Extruded Semisolid Metal

The influence of stress and strain on the solid/liquid segregation formed in deformed semisolid metal was studied. The compression experiment at a low constant strain rate was conducted on a Gleeble 1500 thermo-mechanical simulator.The stress and strain fields of the samples were calculated by finite element method. The experiment results and the modeling results prove that the hydrostatic pressure gradient is the driving force for solid/liquid segregation. The segregated liquid phase usually agglomerates in the micropores and shear bands are created by sliding of equiaxed dendrite grains. The sliding among the grains is influenced by the solid fraction and grain size of the semisolid slurry,so as the solid fraction and grain size change, the morphology of the segregated liquid changes.     

A Novel Fullerene Hydroxamic Acid for the Liquid–Liquid Extraction,Separation, Preconcentration,and Spectrophotometric and ICP‐AES Determination of Vanadium

Abstract

A new reagent N‐phenyl‐(1,2 methanofullerene C₆₀)61‐formohydroxamic acid (PMFFA) is reported for extraction and trace determination of vanadium(V) in nutritional and biological substrates. The extraction mechanism of vanadium from 6 M HCl media is investigated. The influence of PMFFA, diverse ions, and temperature on the distribution constant of vanadium examined. The over all stability constant (log β₂ K _e ) and extraction constant (K _ex) are 20.89 ± 0.02 and 8.0 ± 0.02 × 10^?15, respectively in chloroform. The thermodynamics parameters are calculated and kinetics of vanadium transport is discussed. The system obeys Beer's law in the range of 3.2–64.0 ng mL^?1 of vanadium(V). The molar absorptivity is 7.96 × 10⁵ L mol^?1 cm^?1, at 510 nm. The PMFFA–vanadium(V) complex chloroform extract in chloroform was directly inserted into plasma for ICP‐AES measurement, which increases the sensitivity by 50 folds and obey Beer's law in the range of 50–1200 pg mL^?1 of vanadium(V). The method is applied for determination vanadium in real standard samples, sea water, and environmental samples.     

Characterization of Dielectric Properties in Liquid–Solid Phase Transition

A method for determining the complex dielectric permeability of liquids based on the temperature changes in geometrical parameters (thickness) of samples and over the phase transition range is proposed. Allowing the measurements to be made in a wide temperature range (–190 to 60°C) at different frequencies (0.1–100 kHz), this technique is used for establishing the complex dielectric permeability of ethanol as a function of temperature. The accuracy of coincidence of the obtained values with the data reported in the literature is 3%.     

Metastable States in Liquid–Gas Phase Transition. Simulation by the Method of Molecular Dynamics

The method of molecular dynamics is used to investigate the p, , T-properties and the structural characteristics of the Lennard–Jones fluid in the stable and metastable states in the liquid–gas phase transition. The calculation results demonstrate the presence of phase separation in molecular models at close-to-spinodal supersaturation. The effect of the cut-off radius of the interparticle potential on the process of phase transformation is analyzed, and the position of spinodal of superheated liquid and supersaturated vapor is estimated.     

Study of (Solid–Liquid) Phase Equilibria for Mixtures of Energetic Material Stabilizers and Prediction for Their Subsequent Performance

Solid-liquid equilibria for three binary mixtures of 2-nitrodiphenylamine (1) + diphenylamine (2), ethyl centralite (1) + N-ethyl-4-nitro-N-nitrosoaniline (2), and 2,2 $^{\prime }$ -dinitrodiphenylamine (1) + N-ethyl-4-nitro-N-nitrosoaniline (2) were measured using a differential scanning calorimeter. Simple eutectic behaviors for these systems were observed. The experimental results were correlated by means of original and modified NRTL, Wilson, and UNIQUAC equations. The root–mean–square deviations of the solubility temperatures for all measured data vary from 0.63 K to 3.73 K and depend on the particular model used. The best solubility correlation was obtained with the UNIQUAC model.     

Transient Liquid Phase Bonding of Ni—base Single Crystal Superalloy

The Ni-base single crystal superalloy was bonded by the transient liquid phase(TLP) bonding,using a Ni-base flexible metal cloth as an insert alloy.TLP bonding of superalloy was carried out at 1473-1523K for 0.5-24h in vacuum.The [001] orientation of each test specimen was aligned perpendicular to the joint interface.The bonded region was observed by optical microscopy, and the microstructural and compositional analyses across the bonded interlayer were performed by using a scanning electron microscopy(SEM) .The electron back scattering diffraction(EBSD) method was applied to determine the crystallographic orientation.The resultsindicated that the chemical homogeneity across the bonded region can be achieved,and γˊphase both in the bonded interlayer and in the superalloy substrate is almost identical,while the bonded interlayer had almost matched the crystallographic orientation of the bonded substrates.     

Size Effect in the Phase Separation of Cr–W Solid Solutions

Size effects in phase transformations of nanoscale systems show up as significant changes in their phase diagram. Here, using a thermodynamic approach we demonstrate how the immiscibility region of Cr–W solid solutions is influenced by their particle size. For 40- and 70-nm-diameter particles, we consider two thermodynamically stable states with a core–shell configuration, differing in the composition of the core phase. It is shown that, in the nanometer range, one of these states becomes metastable and that the phase diagrams of the stable and metastable states differ significantly. Reducing the particle size leads to a decrease in the upper critical dissolution temperature (UCDP) by 300–400 K and marked changes in the mutual solubility of the components at temperatures comparable to the UCDP.     

Characterization and Performance of a New Direct Compression Excipient for Chewable Tablets: Xylitab®

Abstract

Xylitab® is a commercially available direct compression form of xylitol. Two grades of this material, Xylitab 200 and Xylitab 100, were evaluated for compaction, flow, lubrication requirements, and dilution potential. As expected, the products required lubrication for tableting, and a level of 0.5% magnesium stearate and 0.5% stearic acid was found to give the best performance. Compaction profiles were generated using both an instrumented single-punch press and a rotary tablet press. Tablets up to hardness values of 20 Kp were obtained on the single-punch press; the maximum hardness values on the rotary press was 11 Kp. Flow behavior on the tablet presses was excellent as shown by tablet weight uniformity data with less than 1% RSD values. Further evaluation by Heckel analysis showed that both products exhibit brittle and viscoelastic behavior, and undergo elastic recovery primarily in the die. To test dilution potential, powdered acetaminophen was selected as a severe test material. Under these conditions, 20% drug still produced an acceptable tablet, but hardness values were reduced as expected. With a directly compressible grade of acetaminophen, a complete chewable formulation was successfully produced using Xylitab 200 as the main direct compression excipient and sweetening agent. Xylitab exhibits acceptable properties as a direct compression chewable tablet excipient and warrants further study.     

Phase Stability, Kinetic Diagrams and Diffusion Path in High Temperature Oxidation of Binary Solid-Solution Alloys

The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kinetic diagrams,which are useful to predict the conditions for the stability of the two mutually insoluble oxides as the external scale, are then calculated on the basis of thermodynamic and kinetic data concerning both the alloys and the oxides, assuming the validity of the parabolic rate law. A combination of the two types of diagrams provides a more detail information about the oxidation behavior of binary alloys. The calculation of the diffusion paths, which relate the oxidant pressure to the composition of the system in terms of the alloy components both in the alloy and in the scale during an initial stage of the reaction in the presence of the parabolic rate law, is finally developed.     

QCM Operation in Liquids: An Explanation of Measured Variations in Frequency and Q Factor with Liquid Conductivity

Recently, several reports have shown that when one side of a quartz crystal microbalance (QCM) is exposed to a liquid, the parallel (but not the series) resonant frequency is influenced by the conductivity and dielectric constant of the liquid. The effect is still controversial and constitutes a serious complication in many applications of the QCM in liquid environments. One suggestion has been that acoustically induced surface charges couple to charged species in the conducting liquid. To explore this effect, we have measured the parallel and the series mode resonance frequencies, and the corresponding Q factors, for a QCM with one side facing a liquid. These four quantities have all been measured versus liquid conductivity, using a recently developed experimental setup. It allows the simultaneous measurement of the resonant frequency and the Q factor of an oscillating quartz crystal, intermittently disconnected from the driving circuit. Based on these results, a simple model together with an equivalent circuit for a quartz crystal exposed to a liquid is presented. The analysis shows that it is not necessary to infer the existence of surface charges (or other microscopic phenomena such as electrical double layers) to account for the influence of the liquid's electrical properties on the resonant frequency. Our results show that the contacting conductive liquid, in effect, enlarges the electrode area on the liquid side and thereby changes the parallel resonant frequency. By proper design of the QCM measurement, perturbing effects due to the liquid's electrical properties can be circumvented.     

Aluminum Fixed Point: Impact of the Time Spent in the Liquid Phase on the Liquid�CSolid Transition and Obviousness of the Pollution of the Ingot

In order to improve the uncertainty on the aluminum fixed point, a study was launched by Laboratoire Commun de Métrologie LNE-CNAM in the frame of the EURAMET Project 732 ??Toward more accurate temperature fixed points?? (coordinating laboratory: France, 17 partner countries). An earlier study completed in this laboratory showed that in regular realization of the melting?Cfreezing plateaus, there is no diffusion of impurities in the thickness of the ingot, or the diffusion is excessively slow and cannot allow a uniform distribution of the impurities. On the other hand, it is frequently noticed that the experimental conditions before the freezing plateau have an impact on its characteristics (value, slope,??). Up to now, no systematic study was performed on the influence of this parameter. So, the objective of the task started recently in this laboratory is to investigate the influence of the time spent in the liquid phase on the phase transition. As a final result, it is demonstrated that in order to reach the equilibrium of the concentration of impurities, it is necessary to ensure that the metal remains in the liquid phase at least 24 h before initiating the freeze. At the end of the process, the aluminum ingot was chemically analyzed. The analyses reveal large contaminations of the surface of the ingot (sodium, sulfur, and phosphorus). One of the important outputs of this study is that the conditions of usage of the cells should be given important attention since large contaminations can be brought by the furnace.     

Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

Standard models for simple metals and insulators often fail for systems based on elements with unstable d- or f-electron shells, where strong electronic correlations can generate new and unexpected states of matter. Such a scenario can often be induced when a magnetic phase transition is tuned to absolute zero temperature by an external control parameter such as chemical composition, pressure or magnetic field. At the resulting quantum critical point (QCP), emergent phenomena, such as unconventional superconductivity and novel magnetic phases are frequently observed. The temperature and energy dependences of the physical properties are also found to deviate from expectations for a simple Fermi liquid. This “non-Fermi-liquid” (NFL) behavior is commonly manifested as weak power laws and logarithmic divergences in the physical properties at low temperatures and is often found in a V-shaped region near a QCP, which has become the “classic” QCP phase diagram. However, there is also a growing number of materials where the NFL behavior either occurs far away from the QCP, within an ordered phase, or may not be associated with any putative QCP. Thus, after nearly 20 years of research, it remains unknown whether NFL physics is universal, or if a multitude of unique subclasses exist. In this article, we review research that has primarily been carried out in our laboratory on systems that exhibit NFL behavior that does not conform to the “classic” QCP scenario.     

Determination of macroconcentrations of platinum by combined application of gravimetry and inductively coupled plasma—Atomic emission spectrometry

A combined method for macroconcentrations of platinum determination in chloroplatinic acid and industrial concentrate obtained during processing of some types of electronic engineering scrap that is based on a combination of gravimetric precipitation of platinum by ammonium chloride with subsequent determination of a residual concentration of platinum in a filtrate using the ISP-AES method is developed. The errors at each stage of analysis, as well as the total error, are estimated. It is shown that the accuracy of macro-concentrations of platinum determination using the combined method is not inferior to the accuracy of classical gravimetric analysis (the relative standard deviation does not exceed 0.15% for 15–40% wt concentrations of platinum). The combined method of analysis based on a combination of gravimetry and ISP-AES makes it possible to decrease labor expenditures and the time of analysis as compared to the classical one.     

Enthalpy of Mixing of Liquid Al—Cr and Cr—Ni Alloys

The partial and the integral enthalpies of mixing of liquid Al-Cr and Ni-Cr binary alloys have been determined by high temperature isoperibolic calorimetry at 1723±5 K and 1729±5 K, respectively. The results were analytically described by the thermodynamically adapted power series (TAPS). The enthalpies of mixing values for both binary liquid melts are small and negative and in good agreement with the available literature data. Minima of the mixing enthalpies of liquid Al-Cr and Ni-Cr alloys are -7.0 kJ·mol-1 at 46 at. pct Cr and -3.0 kJ·mol-1 at 37 at. pct Cr, respectively.     

Determination of Uranium, Thorium, Plutonium, Americium, and Curium Ultratraces by Photon Electron Rejecting α Liquid Scintillation

The determination of activities of thorium, uranium, plutonium, americium, and curium at very low levels has been performed by a new α liquid scintillation system (PERALS, name registered to Ordela, Inc.). The limit of detection has been determined for these nuclides with calculated values often lower than those obtained by other methods, like ICPMS/HP/Mistral, time-resolved laser-induced spectrofluorometry, and α spectrometry. All the results obtained show that the PERALS system is a promising method for the determination of these activities at very low levels. However, its energy resolution is inferior in comparison to that obtained by α spectrometry. For this reason, we have developed a process for separation of the five actinides as quickly and easily as possible. For each actinide, the conditions required to obtain optimal extraction yields and a complete separation have been determined. It is possible to perform the separation in only six extraction steps and to measure activities as low as a few millibecquerels per liter independently. This process has been applied with success to French granitic mineral or doped water and to complex media (biological samples like urines). In this latter case, the extraction recoveries are not quantitative, and it is necessary to determine the recovery yields by labeling with spikes like (230)Th, (232)U, (236)Pu, (248)Cm, and (148)Gd.     

Role of Alloying Elements P, Cu in Liquid Phase Sintering of Short Cast Iron Fiber

The effects of alloying elements P and Cu on the sintering process and mechanical properties of short cast iron fiber compact have been studied. The experimental results show that the sintering can be enhanced obviously by addition of phosphorus. The radial crush strength of sintered compacts increases with P content up to 0.15%, but when P content is over 0.15%,eutectics formed at the interfaces of fibers cause the decrease in strength and quasi-cleavage fracture of the sintered compact. Addition of Cu could not only reduce the volume shrinkage effectively, but also increase the strength and hardness of the sintered compact.