Synthesis and characterization of di‐polyester diamides

A series of di‐polyester diamides was synthesized via a nucleophilic ring opening polymerization process. FTIR investigations revealed the spectral characteristics evidencing the newly formed chemical bonds as well as the changes in the relative intensity of the characteristic peaks, due to the increasing side‐block lengths of the different members of the series. ¹H‐NMR analysis of the described materials confirmed the chemical structures seen by FTIR analysis. The side segment length of the different di‐polyester diamides was calculated from the integration ratios in the NMR spectra. The molecular weight results exhibited relatively small deviations from the stoichiometrically calculated values. All the members of the triblock series, with side blocks of up to 120 lactoyl units, were essentially amorphous and glassy at room temperature. The presence of two separate glass transitions indicated a segmented and microphase separated morphology. It was deducted that the amorphous nature of the relatively long poly(lactic acid) side blocks occurs due to the dominance of the hydrogen‐bonded central segment. Synthesis of a di‐polyester diamide containing a reduced number of hydrogen‐bond‐forming groups in the central segment yielded a partial side‐block crystallization. The di‐polyester diamide with 120 lactoyl unit‐long side blocks was eventually able to crystallize in solid state, following thermal treatment during thermal analysis. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins

Dinuclear nickelphenoxyiminato olefin polymerization catalysts based on rigid p-terphenyl frameworks are reported. Permethylation of the central arene of the terphenyl unit and oxygen substitution of the peripheral rings ortho to the aryl-aryl linkages blocks rotation around these linkages allowing atropisomers of the ligand to be isolated. The corresponding syn and anti dinickel complexes (25-s and 25-a) were synthesized and characterized by single crystal X-ray diffraction. These frameworks limit the relative movement of the metal centers restricting the metal-metal distance. Kinetics studies of isomerization of a ligand precursor (7-a) allowed the calculation of the activation parameters for the isomerization process (ΔH(?) = 28.0 ± 0.4 kcal×mol(-1) and ΔS(?) = -12.3 ± 0.4 cal×mol(-1)×K(-1)). The reported nickel complexes are active for ethylene polymerization [TOF up to 3700 (mol C(2)H(4))×(mol Ni)(-1)×h(-1)] and ethylene/α-olefin copolymerization. Only methyl branches are observed in the polymerization of ethylene, while α-olefins are incorporated without apparent chain walking. These catalysts are active in the presence of polar additives and in neat tetrahydrofuran. The syn and anti isomers differ in polymerization activity and polymer degree of branching and molecular weight. For comparison, a series of mononuclear nickel complexes (26, 27-s, 27-a, 28, 30) was prepared and studied. The effects of structure and catalyst nuclearity on reactivity are discussed.     

Human rectal mucosal gene expression after consumption of digestible and non-digestible carbohydrates

The effect of regular consumption of the low-digestible and prebiotic isomalt versus the digestible sucrose on gene expression in rectal mucosa was examined in a randomized double-blind crossover trial. Nineteen healthy volunteers received 30 g isomalt per day or 30 g sucrose as part of a controlled diet over two 4-week test periods with a 4-week washout period in between. At the end of each test phase rectal biopsies were obtained. After RNA extraction mucosal gene expression was assayed using GeneChip microarrays. In addition, expression of cathelicidin hCap18/LL37, cellular detoxification enzymes GSTpi, UGT1A1 and CYP3A4, cyclooxygenase 2 and barrier factors MUC2 and ZO-1 were determined by real-time RT-PCR. Microbiological analyses of fecal samples revealed a shift of the gut flora towards an increase of bifidobacteria following consumption of the diet containing isomalt. Isomalt consumption did not affect rectal mucosal gene expression in microarray analyses as compared to sucrose. In addition, the expression of cathelicidin LL37, GSTpi, UGT1A1, CYP3A4, COX-2, MUC2 and ZO-1 was not changed in rectal biopsies. We conclude that gene expression of the human rectal mucosa can reliably be measured in biopsy material taken at endoscopy. Dietary intervention with the low digestible isomalt compared with the digestible sucrose did not affect gene expression in the lining rectal mucosa.     

H∞ multiple objective robust controllers forinfinite-horizon single measurement single control input problems

A graphical method is introduced that solves the robust infinite horizon H_∞ multiple-objective control problem for single measurement, single control input systems. The solution is obtained by describing boundaries on the Nichols chart. Each boundary defines the set of all admissible gain and phase values for the loop transmission at a given frequency. These boundaries are obtained by using the well-known parameterization of all the solutions for a single objective H_∞ control problem. The new method links between the theories of H_∞ and quantitative feedback theory (QFT). It can be used to design robust H_∞ controllers with almost no overdesign, and it provides a convenient solution of H_∞ multiple-objective problems that are difficult to solve by the standard four-block setting. It also extends the methods of SISO QFT to deal with a vector of disturbances. The latter may affect the controlled plant through any input coupling matrix and not necessarily through the controller input, or the measurement output     

Formation of glucosyl-deoxyosones from Amadori compounds of maltose

Summary Amadori compounds obtained from maltose were heated witho-phenylenediamine. The main reaction products were found to be the quinoxalines5b,6b, and7a. From the structures of the quinoxalines, it can be deduced that the deoxyosones2b,3b, and4a are formed from maltose. From the determination of some transformation products, it was found that the degradation of glucose in the presence of propylamine does not proceed exclusively with Amadori compound1a as an intermediate. On heating Amadori compound1d, the furane derivative11a was detected, confirming the formation of4a.

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Bildung von Glucosyl-Desoxyosonen aus Amadoriverbindungen der Maltose

Zusammenfassung Amadori-Verbindungen aus Maltose wurden mito-Phenylendiamin umgesetzt. Als wesentliche Reaktionsprodukte konnten die Chinoxaline5b,6b und7a isoliert und identifiziert werden. Die Versuche zeigten, daß bei der Maillard-Reaktion aus Maltose die Substanzen2b,3b und4a als Zwischen-stufen gebildet werden. Durch die Bestimmung von Folgeprodukten ließ sich zeigen, daß der Abbau von Glucose in Gegenwart von Propylamin nicht ausschließlich über das Amadoriprodukt1a erfolgt. Erhitzen der Aminoketose1d führte u. a. zur Bildung des Furanderivates11a, was die Bildung von4a bestätigt.

     

Coherent cold collisions with neutral atoms in optical lattices

By loading a Bose-Einstein condensate into a three-dimensional optical lattice potential, we have been able to demonstrate several fundamental aspects of coherent cold collisions between neutral atoms. We show experimentally how such collisions lead to a well-defined phase shift in the corresponding many-body wave function. The experimental realization of such interactions can be fundamental for the simulation of complex condensed-matter-physics Hamiltonians, for the creation of large-scale entanglement and for the realization of quantum gates with neutral atoms.