Chirality Induction through Nano-Phase Separation: Alternating Network Gyroid Phase by Thermotropic Self-Assembly of X-Shaped Bolapolyphiles.

The single gyroid phase as well as the alternating double network gyroid, composed of two alternating single gyroid networks, hold a significant place in ordered nanoscale morphologies for their potential applications as photonic crystals, metamaterials and templates for porous ceramics and metals. Here, we report the first alternating network cubic liquid crystals. They form through self-assembly of X-shaped polyphiles, where glycerol-capped terphenyl rods lie on the gyroid surface while semiperfluorinated and aliphatic side-chains fill their respective separate channel networks. This new self-assembly mode can be considered as a two-color symmetry-broken double gyroid morphology, providing a tailored way to fabricate novel chiral structures with sub-10 nm periodicities using achiral compounds.

Spontaneous self-assembly of partially fluorinated bolaamphiphiles into ordered layered structures.

We developed a simple method for preparation of well-defined films of X-, T- and anchor-shaped bolaamphiphiles. The compounds were judiciously chosen to investigate the influence of the general molecular structure on the self-assembly properties. Precisely calculated (on the basis of Langmuir π(A) isotherms) volumes of chloroform solutions of the compounds of known concentrations were spread (drop-casted) directly onto the surface of water or silicon wafer. During the solvent evaporation, regular thin films were spontaneously formed. With use of the drop-casting (DC) method, films of thickness of up to three molecular layers could be obtained. X-ray reflectivity (XRR) measurements gave insight into arrangement of the molecules within the films. Different models of molecular organisation in the films were confronted with the experimental results. Advanced fitting procedures allowed for precise determination of the structure of the films. Comparison of films of different compounds obtained using different methods (Langmuir-Blodgett, DC) allowed for a deeper insight into the process of self-assembly, providing guidelines for designing functional molecules spontaneously forming thin, regular films. The proposed DC procedure is a novel alternative to broadly used self-assembled monolayers (SAMs). Unlike SAMs, our method does not require specific molecule-surface interactions and allows formation of films thicker than a monolayer.

Aggregation and layering transitions in thin films of X-, T-, and anchor-shaped bolaamphiphiles at the air-water interface.

Aggregation in Langmuir films is usually understood as being a disorderly grouping of molecules turning into chaotic three-dimensional aggregates and is considered an unwanted phenomenon causing irreversible changes. In this work we present the studies of 11 compounds from the group of specific surfactants, known as bolaamphiphiles, that exhibit reversible aggregation and, in many cases, transition to well-defined multilayers, which can be considered as a layering transition. These bolaamphiphiles incorporate rigid π-conjugated aromatics as hydrophobic cores, glycerol-based polar groups and hydrophobic lateral chains. Molecules of different shapes (X-, T-, and anchor) were studied and compared. The key property of these compounds is the partial fluorination of the lateral chains linked to the rigid cores of the molecules. The most interesting feature of the compounds is that, depending on their shape and degree of fluorination, they are able to resist aggregation and preserve a monolayer structure up to relatively high surface pressures (T-shaped and some X-shaped molecules), or create well-defined trilayers (X- and anchor-shaped molecules). Experimental studies were performed using Langmuir balance, surface potential and X-ray reflectivity measurements.

Evaluation of the Use of Microtracers™ in a Proficiency Testing Program.

Background: An effective proficiency testing program must utilize accurate splitting procedures to ensure that customers receive equivalent (by some measure) test items. When test items are not equivalent, it becomes impossible to separate variation among laboratories from variation among test items, and the program cannot achieve its objectives. Therefore, there is a critical need to validate the splitting process used to manufacture test items. Objective: The incorporation of MicrotracersTM was investigated for validating the splitting process used in the Association of American Feed Control Officials Proficiency Testing Program and as a potential quality control event for a production run. Methods: Microtracers were incorporated into six production runs. From each run, 12 test items were randomly selected for evaluation. Proficiency test materials were prepared from commercially available feedstuffs using base animal feeds and feed additives. The tracers were incorporated into base feed with other additives, recovered, and counted from the randomly selected test items. Results: Uniformity of test items was evaluated with the following two statistical methods: (1) relative standard deviation (RSD) of particle counts according to a Poisson distribution and (2) a Pearson's Chi-square test. RSDs for counts (per mass basis) ranged from 2.49 to 4.13%, and Chi-square P values ranged from 0.0097 to 0.3740 over the six sets. Conclusions: Microtracers were determined to be a potential tool for validating the splitting process used to manufacture proficiency test items and a tool for incorporating quality control events into the manufacture of proficiency test items. Highlights: The authors offer suggestions for proficiency testing programs.

X-Shaped polyphilics: liquid crystal honeycombs with single-molecule walls.

X-Shaped ternary five-block molecules, composed of a rigid p-terphenyl core, two terminal glycerol groups and two flexible n-alkyl or semiperfluorinated chains fixed laterally to opposite sides of the terphenyl moiety, form liquid crystalline phases built up of honeycomb-like arrays of polygonal cylinders, where the rod-like aromatic cores form cylinder walls with a thickness equal to the width of a single molecule.

The changing role of quality assurance in the pharmaceutical industry.

ICH Q10. Pharmaceutical Quality System emphasizes that senior management is responsible for the quality system. Thus, it is not the quality assurance organization that has the primary responsibility for the quality system. With this shift of responsibilities, what can quality assurance do to help senior management fulfill their responsibility? How can quality assurance be more proactive, add more value? What new skills does quality assurance need to have in order to perform its new role? This article attempts to answer these questions.

Arrays of giant octagonal and square cylinders by liquid crystalline self-assembly of X-shaped polyphilic molecules.

Nanopatterning by molecular self-assembly has been a topic of intense research in pursuit of 'bottom-up' methods of generating structures for use in nanotechnology. The systems most widely studied have been two- and three-dimensional morphologies of block copolymers. However, T- and X-shaped polyphilic liquid crystals have recently been shown to have great potential for generating soft honeycomb-like structures, surpassing those of polymers in both complexity and degree of order. The cell cross-section of the liquid crystals honeycombs has so far been limited by small molecular size. Here we overcome this limitation by exploiting the inability of the polyphiles to simultaneously achieve optimal packing and complete nanophase separation. This frustration results in a two-dimensional periodic honeycomb consisting of giant octagonal and square cylinders with circumferences of 12 and 8 molecules, respectively. In addition to forming large cells, the two-molecule-long bendy walls give this structure extra versatility and stability.

Complex multicolor tilings and critical phenomena in tetraphilic liquid crystals.

T-shaped molecules with a rod-like aromatic core and a flexible side chain form liquid crystal honeycombs with aromatic cell walls and a cell interior filled with the side chains. Here, we show how the addition of a second chain, incompatible with the first (X-shaped molecules), can form honeycombs with highly complex tiling patterns, with cells of up to five different compositions ("colors") and polygonal shapes. The complexity is caused by the inability of the side chains to separate cleanly because of geometric frustration. Furthermore, a thermoreversible transition was observed between a multicolor (phase-separated) and a single-color (mixed) honeycomb phase. This is analogous to the Curie transition in simple and frustrated ferro- and antiferromagnets; here spin flips are replaced by 180° reorientations of the molecules.

Reversible aggregation of X-shaped bolaamphiphiles with partially fluorinated lateral chains at the air/water interface.

Langmuir films of four X-shaped bolaamphiphiles were studied using surface pressure and Kelvin potential measurements, Brewster angle microscopy and X-ray reflectivity. The partially fluorinated bolaamphiphiles exhibit an unusual reversibility and reproducibility of Langmuir isotherms, and create very stable and well defined single- or triple layers which can be transferred to solid substrates.