Computational study on the interactions of mustard gas with cucurbituril macrocycles

The study on the absorption of toxic gases such as mustard gas by organic host is essential to the development of inexpensive detection and decontamination equipments. Using quantum chemical methods, we propose cucurbituril as an effective host to capture mustard gas. It was found that stable complexes are formed with the inclusion of the toxic gas molecules inside the cucurbituril cavity, compared with the lateral and exterior interactions. Oxygen mustard has a comparable binding energy with sulfur mustard and hence can be used during experimental investigation. Additionally, during the inclusion complex formation, the presence of heteroatoms helps the guest molecules to undergo a larger structural reorganization to get accommodated inside the cucurbituril macromolecule. Atoms‐in‐molecules analysis shows the existence of strong intermolecular CH…O bonding between the guest molecules and cucurbituril macromolecule. The presence of an intramolecular CH…Cl type of bonding accounts for the higher stabilization of sulfur mustard inside the cucurbituril macromolecule. © 2015 Wiley Periodicals, Inc.     

Thermal decomposition of red-oil/nitric acid mixtures in adiabatic conditions

Formation and thermal decomposition of red-oil during unit operations of nuclear fuel cycle process flowsheets is a severe risk. In the literature, red-oil formation has been investigated thoroughly in general and in detail after Tomsk-7 incident on 6th April 1993. However there is no information on the thermal decomposition of formed red-oil. In this work, results of unique experiments on adiabatic thermal decomposition of red-oil, red-oil equilibrated with excess of 4N nitric acid and 100% TBP equilibrated with excess of 4N nitric acid have been discussed.     

Speciation studies of nitric acid and U(VI) third phases in <Emphasis Type="Italic">n</Emphasis>,<Emphasis Type="Italic">n</Emphasis>-dialkyl amides/<Emphasis Type="Italic">n</Emphasis>-dodecane systems

Conventionally composition of the actinide-extractant solvate is assumed to be the same in the unpartitioned organic phase and the formed third phase. For example, if a m:n solvate has formed during extraction, the solvate is expected to be in the same state even during the third phase condition. However contemporary analysis, based on the spectroscopy measurements and empirical observations, has indicated the presence of an extended solvate. In this article, the proposed speciation in nitric acid and U(VI) third phase formation in n–n dialkyl amide/dodecane-nitric acid systems has been modeled with empirical correlations.     

Measurement of dispersion numbers for 36 and 100% tri-isoamyl phosphate solvents equilibrated with aqueous nitric acid solutions

The cross sections for the ¹¹⁸Sn (n, α)¹¹⁵Cd, ¹²⁰Sn (n, α)^117gCd and ¹²⁰Sn (n, α)^117mCd reactions have been measured in the neutron energy range of 13.5–14.6 MeV using the activation technique and a coaxial HPGe γ-ray detector. The fast neutrons were produced by the T (d, n) ⁴He reaction. The neutron energies in the measurements were determined by cross section ratios for ⁹³Nb(n,2n)^92mNb and ⁹⁰Zr(n, 2n)^89m+gZr reactions. The results of present work were discussed and compared with theoretical calculation data, measurement results found in the literature and with the comprehensive evaluation data in ENDF/B-VII.0, CENDL-3.1, JENDL-4.0 libraries.     

Direct dissolution of intact UO<Subscript>2</Subscript> pellet and in situ extraction by organic solutions of TBP-HNO<Subscript>3</Subscript> at atmospheric pressure: role of solvate composition

Recently authors demonstrated direct dissolution of g-level PHWR UO₂ fuel pellet fragments and in situ extraction by TBP-HNO₃ and TiAP-HNO₃ solutions at atmospheric pressures. Extending the work, similar studies were performed on intact unirradiated PHWR UO₂ fuel pellets (~15 g U) with varying compositions of organic solvate of tri-n-butyl phosphate (TBP). It was observed that extent of dissolution was a strong function of organic solution composition TBP·(HNO₃) _x (H₂O) _y . Complete dissolution of intact UO₂ pellet in a reasonable time was observed only in case of a particular solvate composition.     

Thermal stability of UNEX/HCCD-PEG diluent FS-13

Phenyl trifluoromethyl sulfone (FS-13) is an inert diluent used in HCCD/PEG process for isolation and recovery of cesium and strontium from highly radioactive raffinate waste. There is no experimental data available in open literature describing pressurization due to the thermal decomposition of FS-13 at elevated temperatures. Experiments were conducted for determination of flash point and heating of FS-13 under pressurized closed-vent conditions in an adiabatic calorimeter. During adiabatic experiments, negligible pressurization was observed.     

Two-dimensional surface properties of PEO-PPO-PEO triblock copolymer film at the air/water interface in the absence and presence of Tyr-Phe dipeptide, Val-Tyr-Val tripeptide, SDS and stearic acid

Two-dimensional surface properties of PEO-PPO-PEO triblock copolymer film (Mol.Wt. 2800) in the absence and presence of Tyr-Phe dipeptide, Val-Tyr-Val tripeptide, sodium dodecylsulfate and stearic acid have been investigated for the first time at the air/water interface using Langmuir film balance technique. It is observed that the above polymer forms fairly stable film at the air/water interface. There are no significant changes observed in the surface pressure-area (π-A) isotherms of polymer in the presence of SDS. However, more expanded film was formed in presence of SDS since the solubility of the polymer is more in SDS and the polymer network is disturbed in presence of SDS, which results in the increase in surface area of the polymer films. In the presence of dipeptide and tripeptide, the surface area of the polymer film decreased with a slight increase in the surface pressure indicating the binding of these peptides to polymer, which enhances the stability of the polymer film. Thermodynamic studies on the change in surface area (ΔA) and excess free energy of mixing (ΔG(mix)(E)) associated with the formation of the mixed film suggest the occurrence of a thermodynamically unstable mixed film. The presence of SDS slightly decreases the formation of mixed film of stearic acid with triblock copolymer and peptides due to the solubilization of these compounds in SDS. However, the hydrophobicity of the polymer films increases in the presence of stearic acid, leading to the increase in surface pressure. The positive deviation of ΔA and the positive ΔG(mix)(E) values show the non-ideality and incompatibility of thermodynamically unstable mixed films. The thermodynamic results suggest that the stability and compatibility of the polymer, peptides and their mixed films with stearic acid in the presence of SDS are decreased, which is in good agreement with the results obtained for other polymeric systems.     

Methotrexate intercalated ZnAl-layered double hydroxide

The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.