Phase Equilibria in the Triethylene Glycol– and Tetraethylene Glycol–Supercritical Propane Systems

Phase equilibria in the triethylene glycol–propane and tetraethylene glycol–propane systems at 373, 378, and 383 K and 4 to 45 MPa were studied by IR spectroscopy. The compositions of the coexisting phases throughout the temperature and pressure ranges examined were calculated using the Soave equation with empirical binary interaction parameters. The critical lines for the binary systems likely have discontinuities in the vicinity of the critical point of propane.     

Extraction of Zirconium and Hafnium in Polyethylene Glycol‐Based Aqueous Biphasic System

Abstract

The behavior of zirconium and hafnium in PEG 2000‐Na₂SO₄‐HCl aqueous biphasic system has been investigated. The dependences of HCl concentration (0.185–0.55 M), extraction temperature (298–318 K), and extraction time (5–120 min) on distribution ratios have been determined. Extraction of this metals in PEG 2000‐Na₂SO₄‐H₂SO₄ and PEG 2000‐Na₃Cit‐HCl systems has been also studied. The sulfate and citrate complexes of Zr and Hf prefer salt‐rich phase in contrast to chloride complexes which pass into PEG rich phase in about 50% (w/w) to the greatest degree in room temperature and at short extraction time. The increase of distribution ratios (D*_Zr=3.75, D*_Hf=4.31) was observed after addition of water soluble organic ligand ‐ tiron (4,5‐dihydroxy‐m benzenedisulfonic acid disodium salt). The results obtained in studied conditions are not very useful for the separation of zirconium and hafnium.     

Sharp Demand Increase of Ethylene Glycol Phenyl Ether

Ethylene glycol phenyl ether is a typi-cal organic solvent with low volatil-ity and high boiling point.It is exten-sively used in solvents,Pharmaceuti-cals and daily-use chemicals.     

Effect of Polyethylene Glycol (PEG) Powder on Compressibility and Microstructural Properties of Sintered α-Alumina

This study examines the effect of various contents of polyethylene glycol (PEG) powders on density, compressibility, and microstructural properties of sintered α-alumina samples. Moreover, the effect of compaction pressure on the green density of the compacts is studied by applying different pressures ranging from 400 to 550 MPa. Samples were prepared by mechanical blending of alumina and various amounts of PEG powders in a Turbula mixer. The binder contents vary from 1 wt.% to 4 wt.%. The as-prepared mixture was compacted in a universal machine at room temperature under the pressure of 6 MPa to produce disk-shaped samples in a pre-compaction step. Experimental results revealed that adding various amounts of PEG powders has a detrimental effect on the green density of alumina pellets and decreases the green density from 1.95 to 1.87 g/cm³. The results also show that sintered density of samples increased by increasing the compaction pressure to pressures higher than 400 MPa. It is observed that a sudden increase in green density has been observed between 450 and 550 MPa.     

Solubility and Apparent Specific Volume of Some Pharmaceutical Salts in Propylene Glycol + Water Mixtures at 298.15 K

The equilibrium solubility of three pharmaceutical salts, namely, sodium naproxen (Na.NAP), procaine hydrochloride (PC.HCl), and lysine clonixinate (Lys.Clon), was determined in propylene glycol (PG) + water mixtures at 298.15 K. If the mole fraction concentration scale is considered, the mixtures’ composition-dependence on solubility was different for these drugs. Thus, the solubility of Na.NAP increased nonlinearly from pure water to pure PG. By contrast, the solubility of PC.HCl decreased nonlinearly from pure water to pure PG. In a different way, the solubility of Lys.Clon increased from pure water to the mixture with mass fraction of PG, w₁ = 0.80, and later, it decreased to reach a lower value in pure PG. A good correlation of the solubility data was obtained by using the modified NIBS/R-K model. Otherwise, the apparent specific volumes at saturation of these drugs were also calculated in all the mixtures under study.     

Performance of Composite Membranes of Poly(ether–block–amide) for Dehydration of Ethylene Glycol and Ethanol

Poly(ether–block–amide) (Pebax 2533) membrane was synthesized on a poly(vinylidene fluoride) (PVDF) ultraporous substrate to study the separation of synthetic ethylene glycol/water and ethanol/water mixtures by pervaporation. The membrane was characterized by FTIR spectroscopy, DSC, SEM, and XRD to assess intermolecular interactions, thermal stability, surface morphology, and crystallinity, respectively. Equilibrium sorption studies were carried out in pure liquids and binary alcohol-water mixtures of different compositions to assess polymer-liquid interactions. Pebax 2533 membrane exhibited the requisite potential for dehydration of the alcohols by showing a selectivity of 1254 and water flux of 0.05 kg m^?2 h^?1 for the ethanol azeotrope, whereas the corresponding selectivity for 95% ethylene glycol feed was 978 with a similar flux. The effect of operating parameters such as feed composition and permeate pressure on membrane performance was evaluated. The membrane exhibited considerable feasibility for scale-up with significant potential for alcohol dehydration.     

Preparation of Iminodiacetic Acid-Polyethlene Glycol for Immobilized Metal Ion Affinity Partitioning

1 INTRODUCTIONImmobilized metal ion affinity chromatography(IMAC) is a powerfu tool for the separation ofproteinsI1'2]. Metal amnity separation exPloits theaffinity of transition metal ions for electron-rich aminoacid residues, such as histidine and cysteine, which areaccessible on the surface of proteins. Metal recogni-tion can also be engineered into prOteins for aPplication such as protein purification[3]. Recelltly, immobi-     

Growth,doping and characterization of epitaxial thin films and patterned structures of AlN,GaN, and AlxGa1−xN

Advancements in the doping of GaN and Al_xGa_1−xN thin films, and the growth of GaN and Al_xGa_1−xN structures on patterned heterostructure substrates via metalorganic vapor phase epitaxy are reported. The acceptor-type behavior of Mg-doped GaN films grown in N₂ diluents is presented. Net ionized impurity concentrations up to 8×10¹⁸ cm⁻³ and Hall mobilities up to ≈14 cm² V⁻¹ s⁻¹ were measured for Mg-doped films grown in N₂ in the as-grown condition. Donor and acceptor doping of Al_xGa_1−xN alloys was performed. Acceptor doping of Al_xGa_1−xN for x≤0.13 and donor doping for x≤0.58 were achieved for films deposited at 1100 °C. Lateral epitaxial overgrowth of GaN and Al_xGa_1−xN layers was investigated. The growth and coalescence of GaN and Al_xGa_1−xN stripes patterned in SiO₂ and/or SiN_x masks deposited on GaN, including aligned second lateral epitaxial overgrowth on initial laterally overgrown GaN layers, are discussed.     

Preparation and Evaluation of Poly(Ethylene Glycol)–Poly(Lactide) Micelles as Nanocarriers for Oral Delivery of Cyclosporine A

A series of monomethoxy poly(ethylene glycol)–poly(lactide) (mPEG–PLA) diblock copolymers were designed according to polymer–drug compatibility and synthesized, and mPEG–PLA micelle was fabricated and used as a nanocarrier for solubilization and oral delivery of Cyclosporine A (CyA). CyA was efficiently encapsulated into the micelles with nanoscaled diameter ranged from 60 to 96 nm with a narrow size distribution. The favorable stabilities of CyA-loaded polymeric micelles were observed in simulated gastric and intestinal fluids. The in vitro drug release investigation demonstrated that drug release was retarded by polymeric micelles. The enhanced intestinal absorption of CyA-loaded polymeric micelles, which was comparable to the commercial formulation of CyA (Sandimmun Neoral®), was found. These suggested that polymeric micelles might be an effective nanocarrier for solubilization of poorly soluble CyA and further improving oral absorption of the drug.     

Shaped Refractory Products-Packing, Marking, Transportation and Storage

1 Scope
This standard specifies the technical requirement of the packing, marking, transportation and storage of shaped refractory products.     

Sillimanite,Kyanite and Andalusite in China and Their Applications Part Ⅰ:Their Reserve,Distribution and Characteristics

Sillimanite, kyanite and andalusite areadvantageous natural refractory raw materials foraluminosilicate refractories to attain improved keyproperties. This paper are divided into two parts tointroduce their resource and technical characteristicin the first part, and their applications in refracto-ries in the second part to be succeeded. In this part,based on authors' knowledge and sources, informa-tion on their reserve, distribution, composition and     

Sillimanite,Kyanite and Andalusite in China and Their Applications Part I .Their Reserve,Distribution and Characteristics

Sillimanite,kyanite and andalusite are advantageous natural refractory raw materials for aluminosilicate refactories to attain improved key properties.This paper are divided into parts to introduce their resource and technical characteristic in the first part,and their applications in refractories in the second aprt to be succeeded.In this part,based on authors‘ knowledge and sources,information on their reserve,distribution,composition and characteristic is provided,to bring it to light that China is rich in the reserve of them,in particular andalusite.The sillimanite group minerals are characterized by their phase transformation to form primary mullite and secondary mullite when added in high alumina system,accompanied by volume expansion,which can be taken use to improve creep resistances and thermal shock resistance of the related refractories.     

Oxidative degradation kinetics of lycopene, lutein, and 9-cis and all-trans β-carotene

The thermal and oxidative degradation of carotenoids was studied in an oil model system to determine their relative stabilities and the major β-carotene isomers formed during the reaction. All-trans β-carotene, 9-cis β-carotene, lycopene, and lutein were heated in safflower seed oil at 75, 85, and 95°C for 24, 12, and 5 h, respectively. The major isomers formed during heating of β-carotene were 13-cis, 9-cis, and an unidentified cis isomer. The degradation kinetics for the carotenoids followed a first-order kinetic model. The rates of degradation were as follows: lycopene>all-trans β-carotene≈9-cis β-carotene>lutein. The values for the thermodynamic parameters indicate that a kinetic compensation effect exists between all of the carotenoids. These data suggest that lycopene was most susceptible to degradation and lutein had the greatest stability in the model system of the carotenoids tested. Furthermore, there was no significant difference in the rates of degradation for 9-cis and all-trans β-carotene under the experimental conditions.     

Excess Molar Volumes and Viscosities of Binary Mixtures of p-Xylene with Cyclohexane, n-Heptane, n-Octane, Sulfolane, N-Methyl-2-pyrrolidone and Acetic Acid at 303.15 K and 323.15 K and Atmospheric Pressure

Experimental data on density and viscosity at 303.15 K and 323.15 K are presented for the binary mixtures of p-xylene with cyclohexane, n-heptane, n-octane, sulfolane, N-methyl-S-pyrrolidone and acetic acid. From these data, the excess molar volume and deviations in viscosity have been calculated. The computed quantities have been fitted to the Redlich-Kister Equation to derive coefficients and estimate the standard error values. Results are discussed in terms of intermolecular interactions.     

Effects of Zn, Cu, and K Promoters on the Structure and on the Reduction, Carburization, and Catalytic Behavior of Iron-Based Fischer–Tropsch Synthesis Catalysts

Zn, K, and Cu effects on the structure and surface area and on the reduction, carburization, and catalytic behavior of Fe–Zn and Fe oxides used as precursors to Fischer–Tropsch synthesis (FTS) catalysts, were examined using X-ray diffraction, kinetic studies of their reactions with H₂ or CO, and FTS reaction rate measurements. Fe₂O₃ precursors initially reduce to Fe₃O₄ and then to metallic Fe (in H₂) or to a mixture of Fe_2.5C and Fe₃C (in CO). Zn, present as ZnFe₂O₄, increases the surface area of precipitated oxide precursors by inhibiting sintering during thermal treatment and during activation in H₂/CO reactant mixtures, leading to higher FTS rates than on ZnO-free precursors. ZnFe₂O₄ species do not reduce to active FTS structures, but lead instead to the loss of active components; as a result, maximum FTS rates are achieved at intermediate Zn/Fe atomic ratios. Cu increases the rate of Fe₂O₃ reduction to Fe₃O₄ by providing H₂ dissociation sites. Potassium increases CO activation rates and increases the rate of carburization of Fe₃O₄. In this manner, Cu and K promote the nucleation of oxygen-deficient FeO _x species involved as intermediate inorganic structures in reduction and carburization of Fe₂O₃ and decrease the ultimate size of the Fe oxide and carbide structures formed during activation in synthesis gas. As a result, Cu and K increase FTS rates on catalysts formed from Fe–Zn oxide precursors. Cu increases CH₄ and the paraffin content in FTS products, but the additional presence of K inhibits these effects. Potassium titrates residual acid and hydrogenation sites and increases the olefin content and molecular weight of FTS products. K increases the rate of secondary water–gas shift reactions, while Cu increases the relative rate of oxygen removal as CO₂ instead of water after CO is dissociated in FTS elementary steps. Through these two different mechanisms, K and Cu both increase CO₂ selectivities during FTS reactions on catalysts based on Fe–Zn oxide precursors.     

Inhibition of β-Glucosidase and Esterase by Tannins from Betula, Salix, and Pinus Species

The reaction of tannin fractions isolated from the bark of Betula, Salix, and Pinus species with two enzymes, -glucosidase and esterase, was investigated. The influence of precipitation to the hydrolytic capacity of -glucosidase also was studied. All tannins studied precipitated -glucosidase and esterase, and moderate differences in the precipitating capacities of the tannins were observed. Interestingly, complex formation between -glucosidase and tannin did not markedly affect the activity of the enzyme. Therefore, complex formation during the insect/herbivore feeding does not necessarily change the defense activity of phenolic glycosides or decrease activity of digestive enzymes.