Monooctyl-α-(4-carboxyanilino)benzylphosphonic acid as a new reagent for extraction and separation of lead(II) and bismuth(III)

Monooctyl--(4-carboxyanilino)benzylphosphonic acid (H₂L) was investigated as a novel reagent for the extraction and separation of lead(II) and bismuth(III) from nitrate solutions. Stoichiometric ionization constants of H₂L in ethanol — water mixtures determined by potentiometric NaOH titration had values pK_a1 2.25 and pK_a2 4.33. Ethanol and chloroform solutions of H₂L followed Beer's law at 300 nm and 296 nm, molar absorptivities being 2.94·10⁴ mol^–1·l·cm^–1 and 2.85·10⁴ mol^–1·l·cm^–1, respectively. HNO₃ and HCl were also extracted into chloroform solutions containing H₂L. Bismuth(III) was quantitatively transferred into the chloroform H₂L solution at pH 1, and lead(II) at 3.5. The value of the separation factor D_Bi/D_Pb is 160 at pH 1.     

Intramolecular cyclization of 5-aryl-3-arylamino-4-benzoyl-1h-3-pyrrolin-2-ones to pyrrolo[3,4-<Emphasis Type="Italic">b</Emphasis>]quinolines

It has been shown that 5-aryl-3-arylamino-4-benzoyl-1H-3-pyrrolin-2-ones cyclize in the presence of conc. H₂SO₄ to give pyrrolo[3,4-b]quinolines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1543–1545, October, 2004.     

Comparison of the fragility index of different eudragit polymers determined by activation enthalpies

The present study aimed to apply fragility index (m) of polymers in the determination of the optimal amount of plasticizer in polymer films. The fragility index of different Eudragit polymers (RS, RL, EPO) was assessed by differential scanning calorimerty (DSC), applying the Arrhenius connection (logq–1/T _g). The fragility of Eudragit EPO films proved to be the highest, while in the case of RS and RL, the increase of the alkyl-chain length caused the increase of fragility. Studying the effect of plasticizer (triethyl citrate, TEC) on the m value of Eudragit RL and RS films, a near linear reduction of the fragility index could be observed between 5–30% TEC concentration, but above 30%, this value leveled out to constant.     

Interfacial and micellar properties of binary mixtures of surfactant and phospholipid in an aqueous medium

Mixed micelles formed by zwitterionic surfactant dimethyldodecylammniopropane sulfonate and short-chain phospholipid 1,2-diheptanoyl-sn-glycero-3-phosphocholine in different proportions in an aqueous medium have been studied physicochemically at an air/water interface and in the bulk by using interfacial tension and pyrene fluorescence intensity measurements, respectively. The critical micellar concentration and free energies of micellization and of interfacial adsorption have been determined. The interfacial study reveals that a mixed monolayer is formed at the air/water interface by the adsorption of surfactant and phospholipid monomers. This has been confirmed by evaluating the interfacial parameters; the maximum surface excess, the minimum area per molecule of a surface-active compound, and the Gibbs surface excess related to surface pressure. The nonideality of mixing, expressed in the terms of the regular solution interaction parameter, #, has negative values over the whole mole fraction range. The negative # values indicate the mutual synergism between the surfactant and phospholipid monomers. The equilibrium distribution of components between micelle and monomer phases was evaluated using a theoretical treatment based on excess thermodynamics quantities evaluated by Motomura's formulation.     

A Large Volume Injection Procedure for GC-MS Determination of PAHs and PCBs

A simple on-column injection system for large volume of liquid samples for the GC-MS determination of traces of PAHs and PCBs has been investigated. A deactivated fused silica capillary 20 m × 0.53 mm I.D. and 2 meters of an HP5 column (0.53 mm,1 m film thickness) were used as retention gaps. Injection volumes of 80 L for PAHs and 90 L for PCBs, allow determination of 5–50 ng L^–1 PAHs and 11–44 ng L^–1 PCBs in hexane solution with an RSD of < 10%. The method has been used for the determination of PCBs and PAHs in soil sample.     

Configuration of MFI-type zeolite interacting with the probe molecule P(CH<Subscript>3</Subscript>)<Subscript>3</Subscript> – a theoretical study

With P(CH₃)₃ as the probe molecule adsorbed on titanium silicalite (TS-1) zeolite, the special and important role of T12 site in MFI-type zeolite was clearly elucidated. There are altogether three active sites present in TS-1 zeolite with Ti at the T12 site. Owing to the preferential adsorption of probe molecules on the first Brönsted acidic site, the Ti12 center will probably fail to show Lewis acidity. The ionic [HP(CH₃)₃]⁺ species can be stabilized by the first or second Brönsted acidic site, with the former energetically favored. The latter was formed through the transfer of the ionic [HP(CH₃)₃]⁺ species from the first to the second Brönsted acidic site.     

Seasonal variation and activity size distribution of <Superscript>7</Superscript>Be in ambient air

The seasonal variation of the ⁷Be activities in air and the size distribution of the ⁷Be aerosols were studied by using a continuous air sampler and a five stage cascade impactor. The mean monthly activity level of ⁷Be at the Korea Atomic Energy Research Institute (KAERI) site varied from 0.5 to 4.8 Bq·m⁻³ and revealed a seasonal variation, in which the ⁷Be activity levels were high in winter and low in summer. The mass size distribution showed a bi-modal distribution with a higher peak around 0.49 μm and a smaller peak between 3 μm and 7.2 μm. The activity median aerodynamic diameter (AMAD) decreased with increasing ambient ⁷Be concentrations. The mean residence times by using a mean growth rate of 0.004 μm·h⁻¹ were estimated to be 2.5–6.4 days. The AMAD has an increasing tendency with higher relative humidity. It seemed that the high humidity condition facilitated the growth of the aerosol, resulting in increased deposition rates of the aerosols and the low ⁷Be content in the surface air. The AMAD of the ⁷Be aerosols increased with an increasing temperature, but the temperature dependency of AMAD should be explained with geological and meteorological conditions.     

Behavior of radiocesium in atmospheric arerosol and fallout in Prague

Radiocesium in ground layer atmospheric aerosol and fallout in Prague has been examined. After a decline in 1986–1988, controlled by a sum of two negative exponentials,¹³⁷Cs aerosol concentration reached a constant level based on an equilibrium between its deposition and resuspension. Deposition velocity was compared to that of⁷Be and²²⁶Ra. It confirmed the supposed source of¹³⁷Cs as resuspension from the ground. Resuspension factor of the order of magnitude of 10^–9 was determined, reminding similar values found earlier in Prague as well as those found in Munich. It also agrees well with the USAEC resuspension model. Solubility of¹³⁷Cs was measured in combined wet and dry fallout. The average undissolved fraction of¹³⁷Cs was found to be about 70% which can be explained by the conditions of the¹³⁷Cs aerosol formation in Chernobyl.     

Measurement of the electron distribution function in flowing afterglow plasma by means of Langmuir probe

Conclusion In the present report an attempt has been made to use the second derivative method for measurements of the electron distribution function in flowing afterglow plasma. It has been shown that using the cross-correlation technique, this method seems to be a useful tool for flowing afterglow plasma investigation.