Magnesium and nickel(II) furan‐2,5‐dicarboxylate

The salts hexaaquamagnesium furan‐2,5‐dicarboxylate, [Mg(H₂O)₆](C₆H₂O₅), (I), and hexaaquanickel furan‐2,5‐dicarboxylate, [Ni(H₂O)₆](C₆H₂O₅), (II), provide the first crystallographic characterization of the furan‐2,5‐dicarboxylate dianion. Both structures exhibit extensive three‐dimensional hydrogen‐bonding networks between the octahedral coordinated hexaaquametal(II) ions and the dicarboxylate anions. Although the two structures are not isomorphous, they contain essentially identical two‐dimensional slabs. The distinction between the structures is that these slabs are related by translation in (II), whereas adjacent slabs in (I) are reflected relative to each other by the action of a glide plane. The reflection occurs so that the local contacts between slabs are not changed, and thus the hydrogen‐bond networks are identical except for the orientation of the water molecules at the interface between slabs.     

Visible-light photoredox catalyzed oxidative Strecker reaction

An aerobic photocatalytic oxidative cyanation of tertiary amines providing valuable α-aminonitriles in good to excellent yields was developed. Mild reaction conditions and low catalyst loading are attractive features of the protocol.     

Phase-to-phase and phase-to-amplitude transfer characteristics of a nondegenerate-idler phase-sensitive amplifier

For the first time to our knowledge, the phase-to-phase and phase-to-amplitude transfer functions of a nondegenerate-idler phase-sensitive fiber optic parametric amplifier are experimentally measured. Additionally, analytically and numerically obtained transfer curves show excellent agreement with the experimental curves. The experimental results were obtained by imposing a linear phase modulation onto the signal and idler wave simultaneously, and detecting the input and output signal using a self-homodyne coherent receiver.     

Irreversible investments with delayed reaction: an application to generation re-dispatch in power system operation

In this article we consider how the operator of an electric power system should activate bids on the regulating power market in order to minimize the expected operation cost. Important characteristics of the problem are reaction times of actors on the regulating market and ramp-rates for production changes in power plants. Neglecting these will in general lead to major underestimation of the operation cost. Including reaction times and ramp-rates leads to an impulse control problem with delayed reaction. Two numerical schemes to solve this problem are proposed. The first scheme is based on the least-squares Monte Carlo method developed by Longstaff and Schwartz (Rev Financ Stud 14:113–148, 2001). The second scheme which turns out to be more efficient when solving problems with delays, is based on the regression Monte Carlo method developed by Tsitsiklis and van Roy (IEEE Trans Autom Control 44(10):1840–1851, 1999) and (IEEE Trans Neural Netw 12(4):694–703, 2001). The main contribution of the article is the idea of using stochastic control to find an optimal strategy for power system operation and the numerical solution schemes proposed to solve impulse control problems with delayed reaction.     

Two-dimensional superdegeneracy and structure-magnetism correlations in strong ferromagnet, Mn2Ga5

The ferromagnetic intermetallic compound Mn2Ga5 has been synthesized and characterized by single-crystal X-ray diffraction study and by magnetic property measurements. The compound, with the Mn2Hg5-type structure, exhibits a saturated magnetic moment of 2.71 muB per formula unit with T(C) approximately = 450 K. The electronic structure of the compound was analyzed by employing FPLO, LMTO, and the extended Hückel tight-binding calculations. The nonmagnetic electronic structure of Mn2Ga5 reveals remarkably flat degenerate (superdegenerate) bands in the vicinity of the Fermi level but only in the a*b*-plane of the Brillouin zone. The resulting high density of the states at the Fermi level, DOS(E(F)), is consistent with the Stoner condition for the observed itinerant electron ferromagnetism. Detailed orbital analysis shows an intriguing structure-magnetism correlation, as the superdegeneracy is found to be a consequence of the unique atomic arrangement and bond angles in the structure.     

Activities and identification of aryl hydrocarbon receptor agonists in sediments from the Danube river

This study is a consequence of a distinct fish decline in the Danube river since the beginning of the 1990s. In contrast to the decline of fish population, former studies have repeatedly documented that the water quality along the Danube river is improving. However, the conclusion of a pilot study in 2002 was that a high hazard potential is associated with local sediments. The present study documents that sediment samples from the Danube river showed comparatively high aryl hydrocarbon receptor mediated activity in biotests, using the cell lines GPC.2D.Luc, H4IIE (DR-CALUX) and RTL-W1. The combination of chemical analysis, fractionation techniques and different in vitro tests revealed that priority pollutants could not explain the main induction, even though the concentrations of priority polycyclic aromatic hydrocarbons (PAHs) were very high (maximum in the tributary Schwarzach, sum of 16 EPA PAHs 26 mug/g). In conclusion, this investigation shows that nonpriority pollutants mainly mediate the high induction rates. Nevertheless, owing to the effects of PAHs towards fish and the connection between dioxin-like activity and carcinogenicity, the link between contamination and the fish population decline cannot be ruled out.     

Gold(I)-catalysed synthesis of cyclic sulfamidates by intramolecular allene hydroamination

Six-membered cyclic sulfamidates are prepared in high yields by treatment of allenic sulfamates with readily available gold(I) complexes. The reaction enables formation of N-substituted quaternary centres and complements existing processes for sulfamidate formation.     

Measurement of interaction forces between lignin and cellulose as a function of aqueous electrolyte solution conditions

The interaction between a lignin film and a cellulose sphere has been measured using the colloidal probe force technique as a function of aqueous electrolyte solution conditions. The lignin film was first studied for its roughness and stability using atomic force microscopy imaging and quartz crystal microbalance measurements, respectively. The film was found to be smooth and stable in the pH range of 3.5-9 and in ionic strengths up to and including 0.01 M. This range of ionic strength and pH was hence used to measure the surface force profiles between lignin and cellulose. Under these solution conditions, the measured forces behaved according to DLVO theory. The force-distance curves could be fitted between the limits of constant charge and constant potential, and the surface potential of the lignin films was determined as a function of pH. At a pH greater than 9.5, a short range steric repulsion was observed, indicating that the film was swelling to a large extent but did not dissolve. Thus, lignin films prepared in this manner are suitable for a range of surface force studies.     

Flow splitting at the inlet electrode as a method for decreasing the electric current in electric field assisted liquid chromatography

The combination of pressurized flow and electric field offers, with the use of capillary columns, several options for retention control. However, it has been shown that the utility of this technique is strongly limited by the high electric current that is generated at the high electric field strengths that are needed. We have earlier shown that the high current is a result of locally increased mobile phase ion concentration in the electric field, particularly around the inlet electrode. In this paper, we report that by splitting the mobile phase flow around the inlet electrode a relatively constant ion concentration around the electrode can be obtained and the high currents are there by reduced.