Interactions between benzyl benzoate and single- and double-chain quaternary ammonium surfactants

Interactions between benzyl benzoate and two different twin-tailed cationic surfactants have been studied. NMR diffusometry measurements have shown that cationic micelles grow in one dimension when benzyl benzoate is added. The location of benzyl benzoate in the micelles was evaluated by NOESY, showing that benzyl benzoate gave cross-peaks both to the hydrophobic groups in the surfactant and to the surfactant head group. Additions of benzyl benzoate to a lamellar phase of double-tailed quaternary surfactants revealed differences in responses. With an increasing concentration of benzyl benzoate, the structure of the dialkyl quat aggregate goes from lamellar to cubic, while the dialkyl ester quat forms a lamellar structure for all benzyl benzoate concentrations.     

4‐(4‐Bromo­phenyl)‐2‐methyl‐1,3‐thia­zole

In the structure of the title compound, C₁₀H₈BrNS, the dihedral angles between the planes of the thia­zole and aryl rings, viz. 4.2 (6) and 7.5 (6)° for the two independent mol­ecules, are consistent with insignificant molecular perturbation by the weak intermolecular contacts. The mol­ecules are close to being related by a non‐crystallographic inversion centre, with C—H⃛π and π–π intermolecular interactions observed.     

X‐ray photoelectron spectroscopy process optimization for characterization of trace contamination elements for extreme ultraviolet resist outgassing study

X‐ray photoelectron spectroscopy (XPS) is used for elemental identification and quantification in a number of fields, and the optimization of XPS performance can help in making better use of the limited XPS tool availability. In the field of extreme ultraviolet (EUV) lithography, one of the requirements is having a clean vacuum environment to minimize contamination of the EUV optics. EUV resist outgassing is viewed as one of the main issues that could affect the vacuum environment. There is a program underway to measure the relative contamination rates from different resists following the ASML (provider of lithography systems) approved protocols for witness plate testing. One of the key steps is the XPS measurement of residue on the optics after cleaning. The role of XPS in quantification of species that adhere to the ruthenium‐coated silicon witness plate sample is discussed. The various XPS tool parameters like the pass energy and source setting were optimized for our application of witness plate analysis. The statistics of our XPS tool were studied, and combined with the fundamental XPS equations, a simple mathematical model was developed to optimize the number of scans for the various elements of interest in our witness plate study. Using the optimized number of scans, the acquisition time to measure the contaminant elements to a precision better than 0.1 at.% was minimized. The model devised in the paper can be adapted to other XPS measurements requiring different levels of precision. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis of pyrrolo[1,3]diazepines by a dipolar cycloaddition—retro-Mannich domino reaction

Microwave irradiation facilitated the synthesis of 4-arylthio-3-oxazolin-5-ones from ethyl cyanoformate, thiophenol, and cyclic ketones. Subsequent decarboxylation and in situ [3+2] cycloaddition provided novel 2,3,4,5-tetrahydro-1H-pyrrolo[1,2-c][1,3]diazepine scaffolds after a spontaneous retro-Mannich domino reaction.     

Rapid measurements of neptunium oxidation states using chromatographic resins

The Savannah River Site’s (SRS) H-Canyon facility uses ceric ammonium nitrate (CAN) to separate impure neptunium (Np) from a nitric acid feed stream containing 0.5–1.0 M concentrations of iron, sodium and sulfate impurities. The material is processed using a two-pass solvent extraction purification which relies on CAN to oxidize Np to Np(VI) during the first pass prior to extraction. Spectrophotometric oxidation-state analyses normally used to validate successful oxidation to Np(VI) prior to extraction were compromised by this feed stream matrix. Therefore, a rapid chromatographic method to validate successful Np oxidation was developed using Eichrom Industries’ TRU and TEVA^® resins. The method was validated and subsequently transferred to existing operations in the process analytical laboratories.     

Monitoring of bentonite pore water with a probe based on solid-state microsensors

Repositories for the disposal of radioactive waste generally rely on a multi-barrier system to isolate the waste from the biosphere. This multi-barrier system typically comprises the natural geological barrier provided by the repository host rock and its surroundings and an engineered barrier system (EBS). Bentonite is being studied as an appropriated porous material for an EBS to prevent or delay the release and transport of radionuclides towards biosphere. The study of pore water chemistry within bentonite barriers will permit to understand the transport phenomena of radionuclides and obtain a database of the bentonite-water interaction processes. In this work, the measurement of some chemical parameters in bentonite pore water using solid-state microsensors is proposed. Those sensors are well suited for this application since in situ measurements are feasible and they are robust enough for the long periods of time that monitoring is needed in an EBS. A probe containing an ISFET (ion sensitive field effect transistor) for measuring pH, and platinum microelectrodes for measuring conductivity and redox potential was developed, together with the required instrumentation, to study the chemical changes in a test cell with compacted bentonite. Response features of the sensors’ probe and instrumentation performance in synthetic samples with compositions similar to those present in bentonite barriers are reported. Measurements of sensors stability in a test cell are also presented.     

Two new sesquiterpene lactones from the leaves of Laurus nobilis

As a part of our ongoing interest in new bioactive compounds from natural sources, we studied Laurus nobilis (Lauraceae). This plant is widespread in the Mediterranean area and is used for medicinal and economic purposes. Chromatographic separations on active extracts led to the isolation of two new sesquiterpene lactones, 5a,9-dimethyl-3-methylene-3,3a,4,5,5a,6,7,8-octahydro-1-oxacyclopenta[c]azulen-2-one (1) and 3beta-chlorodehydrocostuslactone (2). The structures of the new compounds were identified by 1D and 2D NMR experiments, as well as high resolution mass spectrometry. The cytotoxic activity was also evaluated against three different tumor cell lines of human origin.