Computer simulation for the convenient optimization of isocratic reversed-phase liquid chromatographic separations by varying temperature and mobile phase strength

The review summarizes the most recent developments in the field of enantioseparation of chiral drugs using capillary electromigration techniques. The basic principles of enantioseparations in CE are discussed. Recent developments in sample introduction, separation and detection in capillary electrophoresis and capillary electrochromatography are summarized. The applications are arbitrarily divided into the following three groups: (a) racemates and artificial mixtures of enantiomers, (b) drug forms and (c) chiral drugs and their metabolites in biological fluids. Among the various techniques involved the relatively new developments such as CEC in aqueous and nonaqueous buffers, on-line CE-MS coupling, etc. are emphasized.     

Cycloaddition reactions of thiazolium azomethine ylides: application to pyrrolo[2,1-b]thiazoles

Thiazolium azomethine ylides, equipped with a C-2 methanethiol group, participate in an efficient [3 + 2] cycloaddition reaction with acetylene derivatives to yield unique pyrrolo[2,1-b]thiazoles. The elimination of the methanethiol leaving group from the cycloadduct has replaced the need for a separate oxidation step and suppresses ring-opening side reactions. Products were obtained in short synthetic sequences to demonstrate their use as a scaffold for compound libraries.     

Role of long-range intermolecular forces in the formation of inorganic nanoparticle clusters

An understanding of the role played by intermolecular forces in terms of the electron density distribution is fundamental to the understanding of the self-assembly of molecules in the formation of a molecular crystal. Using ab initio methods capable of describing both short-range intramolecular interactions and long-range London dispersion interactions arising from electron correlation, analyses of inorganic dimers of As(4)S(4) and As(4)O(6) molecules cut from the structures of realgar and arsenolite, respectively, reveal that the molecules adopt a configuration that closely matches that observed for the crystal. Decomposition of the interaction energies using symmetry-adapted perturbation theory reveals that both model dimers feature significant stabilization from electrostatic forces as anticipated by a Lewis acid/Lewis base picture of the interaction. London dispersion forces also contribute significantly to the interaction, although they play a greater role in the realgar structure near equilibrium than in arsenolite.     

Characterisation of valves as sound sources: Fluid-borne sound

The sound pressure level in receiving rooms, caused by taps at the ends of pipe systems, is considered. The structure-borne sound power, from the pipes to the supporting wall, was obtained from intensity measurement of the fluid-borne sound power of the tap. The fluid-borne sound power is combined with a ratio of structure-borne sound power to fluid-borne sound power, obtained from laboratory measurements of similar pipe assemblies. Alternatively, a reception plate method is proposed, which avoids the necessity for intensity measurements. The structure-borne power into walls, to which the pipe work is attached, provides input to the standard building propagation model, which yields the predicted sound pressure level in the adjacent room.     

Synthesis and biochemical evaluation of 3,7-disubstituted farnesyl diphosphate analogues

Farnesyl diphosphate (FPP) analogues have proven to be both potent inhibitors of protein-farnesyltransferase (FTase) and valuable probes for the investigation of the function of prenylated proteins. Previously, we have demonstrated that certain 3-substituted and 7-substituted FPP analogues can act as inhibitors of FTase, while others are effective alternative substrates. We have now utilized our vinyl triflate-mediated route to synthesize the first seven FPP variants bearing substituents in both the 3- and 7-positions of the isoprene unit. Despite their exceptional steric bulk with respect to FPP itself, six of the seven analogues bind to FTase. Two of the analogues are potent inhibitors of the enzyme, but a more striking finding is that three FPP variants (4a, 4b, and 4f) are efficient alternative substrates for FTase.     

A Humanized In Vitro Model of Innervated Skin for Transdermal Analgesic Testing

Sensory innervation of the skin is essential for its function, homeostasis, and wound healing mechanisms. Thus, to adequately model the cellular microenvironment and function of native skin, in vitro human skin equivalents (hSE) containing a sensory neuron population began to be researched. In this work, a fully human 3D platform of hSE innervated by induced pluripotent stem cell-derived nociceptor neurospheres (hNNs), mimicking the native mode of innervation, is established. Both the hSE and nociceptor population exhibit morphological and phenotypical characteristics resembling their native counterparts, such as epidermal and dermal layer formation and nociceptor marker exhibition, respectively. In the co-culture platform, neurites develop from the hNNs and navigate in 3D to innervate the hSE from a distance. To probe both skin and nociceptor functionality, a clinically available capsaicin patch (Qutenza) is applied directly over the hSE section and neuron reaction is analyzed. Application of the patch causes an exposure time-dependent neurite regression and degeneration. In platforms absent of hSE, axonal degeneration is further increased, highlighting the role of the skin construct as a barrier. In sum, an in vitro tool of functional innervated skin with high interest for preclinical research is established.     

Synthesis and characterization of ultrathin WO3 nanodisks utilizing long-chain poly(ethylene glycol)

Metal oxide nanostructures hold great potential for photovoltaic (PV), photoelectrochemical (PEC), and photocatalytic applications. Whereas thin films of various materials of both nanoparticle and nanorod morphologies have been widely investigated, there have been few inquiries into nanodisk structures. Here, we report the synthesis of ultrathin WO3 nanodisks using a wet chemical route with poly(ethylene glycol) (PEG) as a surface modulator. The reported nanodisk structure is based on the interaction of the nonionic 10000 g/mol PEG molecules with tungsten oxoanion precursors. The WO3 nanostructures formed are dominated by very thin disks with dimensions on the nanometer to micrometer scale. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images reveal the structures to have dimensions on the order of 350-1000 nm in length, 200-750 nm in width, and 7-18 nm in thickness and possessing textured single-crystalline features. A number of analytical techniques were used to characterize the WO3 nanodisks, including selected-area electron diffraction (SAED), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), Raman scattering spectroscopy, UV-visible spectrophotometry, and cyclic voltammetry (CV). The growth of the WO3 nanodisks was inhibited in the [010] crystal direction, leading to ultrathin morphologies in the monoclinic crystal phase. The large flat surface area and high aspect ratio of the WO3 nanodisks are potentially useful in PEC cells for hydrogen production via direct water splitting, as has been demonstrated in a preliminary experiment with external bias.