Kinetics of competitive crystallization of β- and α-modifications in β-nucleated iPP studied by isothermal stepwise crystallization technique

Crystallization kinetics of β-nucleated isotactic polypropylene (β-iPP) under isothermal conditions were investigated by differential scanning calorimetry. iPP was nucleated by a trisamide derivative, namely tris-2,3-dimethyl-hexylamide of trimesic acid (TATA). In the presence of TATA possessing dual nucleating ability, the formation of the α- and β-form occurs simultaneously. An isothermal stepwise crystallization method is suggested in this study, which can separate the crystallization process of β- and α-iPP and consequently their crystallization kinetics can be evaluated separately. The results indicated that the mechanism of crystallization changes in temperature especially in the vicinity of the upper critical temperature of the formation of the β-phase. In addition, it was found that the ratio of the growth rates of β- and α-modification determines the characteristics of crystallization and influences the apparent rate constant of crystallization of both polymorphs.     

Generation of 220 mJ nanosecond pulses at a 10 Hz repetition rate with excellent beam quality in a diode-pumped Yb:YAG MOPA system

A novel all-diode-pumped master oscillator power amplifier system based on Yb:YAG crystal rods has been developed. It consists of a Q-switched oscillator delivering 3 mJ, 6.4 ns pulses at a 10 Hz repetition rate and an additional four-pass amplifier, which boosts the output energy to 220 mJ, while a close to TEM(00) beam quality could be observed. Additionally a simulation of the amplification was written that allows for further scaling considerations.     

Moving boundaries in sodium dodecyl sulfate-polyacrylamide gel electrophoresis

In sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), moving boundaries I-IV (Table 1) form. They migrate isotachophoretically at displacement rates that increase in the order of I to II to III. Moving boundaries IV and V comprising Pyronin-SDS as a leading constituent are retarded at high gel concentrations in comparison with the isotachophoretically migrating species. Since analytes depending on their net mobilities stack within any of those moving boundaries, previous R(f) values and Ferguson plots may have to be revised.     

An electroelution apparatus for sequential transfer of sodium dodecyl sulfate-proteins into agarose and mass spectrometric identification of Li-Na-dodecyl sulfate-proteins from solubilized agarose

Separated protein bands are sequentially electrophoresed into low melting agarose plugs distributed in an apparatus of original design along the surface of a plastic drum. The rotation of the drum is synchronized to migration of electrophoretic bands to receive each band individually. Agarose plugs are dissolved enzymatically for transfer into the mass spectrometer. One microL of the agarose solution containing 1 pmol of each of three lithium and natrium salts of dodecyl sulfate (Li-Na-DS)-proteins were applied to matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) without any prepurification. It yields a signal indistinguishable from that obtained in the absence of agarose.     

On Weighted Kernels of Two Posets

A recent result of Aharoni Berger and Gorelik (Order 31(1), 35–43, 2014) is a weighted generalization of the well-known theorem of Sands Sauer and Woodrow (Theory Ser. B 33(3), 271–275, 1982) on monochromatic paths. The authors prove the existence of a so called weighted kernel for any pair of weighted posets on the same ground set. In this work, we point out that this result is closely related to the stable marriage theorem of Gale and Shapley (Amer. Math. Monthly 69(1), 9–15, 1962), and we generalize Blair’s theorem by showing that weighted kernels form a lattice under a certain natural order. To illustrate the applicability of our approach, we prove further weighted generalizations of the Sands Sauer Woodrow result.     

Selectivity of methylation of some new [1,2,3]triazolo[4,5-d]pyridazines and structure elucidation by H–N NMR spectroscopy

Alkylation of some selected [1,2,3]triazolo[4,5-d]pyridazines having five or more nitrogen atoms capable for alkylation was investigated. Pyridyl derivatives substituted also on the [1,2,3]triazole ring gave quaternary pyridinium salts, whereas in the case of the analogues compounds unsubstituted at the triazole moiety, the alkylation of the triazole ring was also observed. Unambiguous structure elucidation was provided by ¹H–¹⁵N HMBC experiments which also allowed the assignment of the ¹⁵N NMR shifts.