A pulsed light generator for high speed photography

A pulsed light generator for stroboscopic photography which makes use of LED's has been developed. The maximum light power which may be extracted from a single LED is approximately 1 Watt. The pulse repetition rate ranges up to 1 MHz and the length of the pulses is adjustable between 0.05 and 1 s. The light emitted from the diodes is especially suited for the observation of phase objects by interferometric methods due to its pronounced coherence. Results of the electrical and optical performance of the generator are presented.     

Novel extracellular polymeric substances produced by Cupriavidus necator IPT 027 grown on glucose and crude glycerol originated from biodiesel

The aim of this study was to evaluate the production and properties of novel extracellular polymeric substances (EPS) from glucose (EPS 1) and crude glycerol (CG) from castor beans oil (EPS 2). Cupriavidus necator IPT 027 cultivated with glucose and CG (35 °C, 150 rpm, 72 hr, pH 7, shaker) produced approximately 1.60 ± 0.01 and 2.83 ± 0.02 g l^?1 EPS, respectively, with high‐molecular weight (3.89 × 10⁵ and 1.89 × 10⁷ Da) and constituted of different functional groups such as uronic acid, monosaccharides (glucose, mannose, arabinose, and fucose) and primary amine group. The composition of the fermentable substrate influenced the melting temperature (221.11 and 230.18 °C), crystallinity (34.36% and 37.11%), degradation temperature (255.06 and 296.62 °C) and morphology. EPS showed pseudoplastic non‐Newtonian fluid behavior in the aqueous solutions, presenting potential applicability biotechnological and industrial mainly in food industry as emulsifiers and biosurfactants. This is the first study on the production and characterization of EPS obtained by C. necator IPT 027 in culture with glucose and CG. Copyright © 2016 John Wiley & Sons, Ltd.     

A convergent synthesis of the immunosuppressant FTY720 employing aqueous Wittig chemistry

A short, convergent synthesis of the immunosuppressant FTY720 is described involving the use of 4-hydroxymethylbenzaldehyde as a pivotal intermediate. A double Wittig strategy was developed to connect this dual-functional aldehyde with an alkyl-tether and to a readily available TRIS-derivative leading to an efficient synthesis of the target molecule.     

Directing/protecting groups mediate highly regioselective glycosylation of monoprotected acceptors

A directing/protecting group designed for regioselective functionalization of partially-protected glucopyrannosides has been successfully used to prepare disaccharides in high yields. Most importantly, it has been demonstrated that highly regioselective and stereoselective glycosylation can be achieved when disarmed donors are employed. This study demonstrates the ability of directing/protecting group to induce regioselective glycosylation of carbohydrates and opens the field to the design of other DPGs for other monosaccharides.     

Directed organization of C70 kagome lattice by titanyl phthalocyanine monolayer template

Controlled deposition of titanyl phthalocyanine (TiOPc) on Ag(111) produces a honeycomb monolayer phase consisting of TiOPc molecules with two distinctive tilt angles. This periodic arrangement of polar molecules is used to direct C(70) growth into low-density 3D films with novel C(70) kagome lattice arrangements. Structural models for the C(70) kagome lattice are determined from layer-by-layer scanning tunneling microscopy images and related to the dipolar TiOPc template and C(70)'s anisotropic polarizability. Molecular templates with designed electrostatic features offer a practical method to control 3D film organization on the nanoscale by harnessing anisotropic molecular interactions at the growth interface.     

Effect of cyclization of N-terminal glutamine and carbamidomethyl-cysteine (residues) on the chromatographic behavior of peptides in reversed-phase chromatography

N-terminal loss of ammonia is a typical peptide modification chemical artifact observed in bottom-up proteomics experiments. It occurs both in vivo for N-terminal glutamine and in vitro following enzymatic cleavage for both N-terminal glutamine and cysteine alkylated with iodoacetamide. In addition to a mass change of −17.03 Da, modified peptides exhibit increased chromatographic retention in reversed-phase (RP) HPLC systems. The magnitude of this increase varies significantly depending on the peptide sequence and the chromatographic condition used. We have monitored these changes for extensive sets (more than 200 each) of tryptic Gln and Cys N-terminated species. Peptides were separated on 100 Å pore size C18 phases using identical acetonitrile gradient slopes with 3 different eluent compositions: 0.1% trifluoroacetic acid; 0.1% formic acid and 20 mM ammonium formate at pH 10 as ion-pairing modifiers. The observed effect of this modification on RP retention is the product of increased intrinsic hydrophobicity of the modified N-terminal residue, lowering or removing the effect of ion-pairing formation on the hydrophobicity of adjacent residues at acidic pHs; and possibly the increased formation of amphipathic helical structures when the positive charge is removed. Larger retention shifts were observed for Cys terminated peptides compared to Gln, and for smaller peptides. Also the size of the retention increase depends on the eluent conditions: pH 10 ? trifluoroacetic acid < formic acid. Different approaches for incorporation these findings in the peptide retention prediction models are discussed.     

Self-doping of molecular quantum-dot cellular automata: mixed valence zwitterions

Molecular quantum-dot cellular automata (QCA) is a promising paradigm for realizing molecular electronics. In molecular QCA, binary information is encoded in the distribution of intramolecular charge, and Coulomb interactions between neighboring molecules combine to create long-range correlations in charge distribution that can be exploited for signal transfer and computation. Appropriate mixed-valence species are promising candidates for single-molecule device operation. A complication arises because many mixed-valence compounds are ions and the associated counterions can potentially disrupt the correct flow of information through the circuit. We suggest a self-doping mechanism which incorporates the counterion covalently into the structure of a neutral molecular cell, thus producing a zwitterionic mixed-valence complex. The counterion is located at the geometrical center of the QCA molecule and bound to the working dots via covalent bonds, thus avoiding counterion effects that bias the system toward one binary information state or the other. We investigate the feasibility of using multiply charged anion (MCA) boron clusters, specifically closo-borate dianion, as building blocks. A first principle calculation shows that neutral, bistable, and switchable QCA molecules are possible. The self-doping mechanism is confirmed by molecular orbital analysis, which shows that MCA counterions can be stabilized by the electrostatic interaction between negatively charged counterions and positively charged working dots.