Separation of twenty-one naphthalene sulfonates by means of capillary electrophoresis

The production and use of naphthalene sulfonates can easily cause pollution of surface and other types of waters. In the present study, capillary electrophoresis in combination with UV absorption detection was used to separate 21 amino- and hydroxy-substituted naphthalene sulfonates which included multiple isomeric compounds. The influence of various parameters such as pH (which turned out to be extremely important), temperature of the surrounding air flow, and the use of buffer additives (micelles, cyclodextrins, organic modifiers) was studied. Complete separation of all analytes including the isomers, was achieved in two runs with a 50 mM boric acid/borate buffer, containing either 100 mM sodium dodecylsulfonate or 15% acetonitrile. The limits of detection obtained for the individual compounds typically were 20μgI⁻¹. River water samples spiked at this concentration level could be analysed using a simple three-step sample clean-up procedure.     

Ruthenium Polypyridyl Complexes Hopping at Anionic Lipid Bilayers through a Supramolecular Bond Sensitive to Visible Light

The new ruthenium complex [Ru(terpy)(dcbpy)(Hmte)](PF(6) )(2) ([2](PF(6) )(2) ; dcbpy=6,6'-dichloro-2,2'-bipyridine, terpy=2,2';6',2"-terpyridine, Hmte=2-(methylthio)ethanol) was synthesized. In the crystal structure, this complex is highly distorted, revealing steric congestion between dcbpy and Hmte. In water, [2](2+) forms spontaneously by reacting Hmte and the aqua complex [Ru(terpy)(dcbpy)(OH(2) )](2+) ([1](2+) ), with a second-order rate constant of 0.025?s(-1) M(-1) at 25?°C. In the dark, the Ru?S bond of [2](2+) is thermally unstable and partially hydrolyzes; in fact, [1](2+) and [2](2+) are in an equilibrium characterized by an equilibrium constant K of 151?M(-1) . When exposed to visible light, the Ru?S bond is selectively broken to release [1](2+) , that is, the equilibrium is shifted by visible-light irradiation. The light-induced equilibrium shifts were repeated four times without major signs of degradation; the Ru?S coordination bond in [2](2+) can be described as a robust, light-sensitive, supramolecular bond in water. To demonstrate the potential of this system in supramolecular chemistry, a new thioether-cholesterol conjugate (4), which inserts into lipid bilayers through its cholesterol moiety and coordinates to ruthenium through its sulfur atom, was synthesized. Thioether-functionalized, anionic, dimyristoylphosphatidylglycerol (DMPG), lipid vesicles, to which aqua complex [1](2+) efficiently coordinates, were prepared. Upon exposure of the Ru-decorated vesicles to visible light, the Ru?S bond is selectively broken, thus releasing [1](2+) that stays at the water-bilayer interface. When the light is switched off, the metal complex spontaneously coordinates back to the membrane-embedded thioether ligands without a need to heat the system. This process was repeated four times at 35?°C, thus achieving light-triggered hopping of the metal complex at the water-bilayer interface.     

The impact of order batching and picking area zoning on order picking system performance

This paper proposes an approximation model based on queuing network theory to analyze the impact of order batching and picking area zoning on the mean order throughput time in a pick-and-pass order picking system. The model includes the sorting process needed to sort the batch again by order. Service times at pick zones are assumed to follow general distributions. The first and second moments of service times at zones and the visiting probability of a batch of orders to a pick zone are derived. Based on this information, the mean throughput time of an arbitrary order in the order picking system is obtained. Results from a real application and simulation show that this approximation model provides acceptable accuracy for practical purposes. Furthermore, the proposed method is simple and fast and can be easily applied in the design and selection process of order picking systems.     

Design and control of warehouse order picking: A literature review

Order picking has long been identified as the most labour-intensive and costly activity for almost every warehouse; the cost of order picking is estimated to be as much as 55% of the total warehouse operating expense. Any underperformance in order picking can lead to unsatisfactory service and high operational cost for the warehouse, and consequently for the whole supply chain. In order to operate efficiently, the order-picking process needs to be robustly designed and optimally controlled. This paper gives a literature overview on typical decision problems in design and control of manual order-picking processes. We focus on optimal (internal) layout design, storage assignment methods, routing methods, order batching and zoning. The research in this area has grown rapidly recently. Still, combinations of the above areas have hardly been explored. Order-picking system developments in practice lead to promising new research directions.     

Dislocation Structure of Grain Boundaries in Single Crystals Deforming in Simple Shear

A model for the formation of grain boundaries in single crystals having a single active slip system for the case of plane strain simple shear is proposed. It is shown that non-convexity of the condensed energy gives rise to the formation of a laminate structure, where sharp interfaces between laminate layers are interpreted as grain boundaries. Based on these results the dislocation structure of the boundaries is determined introducing a transition zone between laminate layers, where smooth functions of displacement and plastic slip connect adjacent layers. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ammonhaltiges doppeltkohlensaures Natron

Ohne Zusammenfassung     

μ+knight shifts and trapping in diluteSbSn alloys

Giant μ⁺ Knight shifts K_μ have been studied previously in Sb andSbBi alloys. Here we report μ⁺SR measurements on Sb with dilute heterovalent Sn impurities. A dramatic concentration dependence is observed: K_μ is increased slightly (relative to the value in pure Sb) by Sn concentrations of <0.1%, whereas larger concentrations cause a drastic reduction of K_μ. One concern could be that K_μ values in the alloy might reflect local band structure in trap sites near Sn impurities rather than the bulk “host” band structure of the alloy. This is indeed the case in bothSbSn (0.03%) andSbSn (0.06%), where a second, lower frequency TF-μSR signal begins to appear for T>60K. The amplitude of the low K_μ signal grows with increasing T at the expense of the amplitude of the high-K_μ, low-T signal, suggesting that the μ⁺ migrates through the host lattice to trap sites. A simple trapping model correctly describes the observed T-dependence of the amplitudes, phases and relaxation rates of the two signals. We conclude that the low-T Knight shift is truly characteristic of the host band structure while the much lower K_μ value of the high-T site is characteristic of a specific trap site, presumably adjacent to a Sn impurity.     

Development of frozen whale blubber and liver reference materials for the measurement of organic and inorganic contaminants

Summary Fresh frozen homogenates of pilot whale blubber and liver tissue were prepared for use as control materials for the determination of organic and inorganic contaminants in marine mammal tissue analyses. The blubber material was analyzed to determine 30 polychlorinated biphenyl congeners and 16 chlorinated pesticides using gas chromatography with electron capture detection and gas chromatographymass spectrometry. A total of 39 trace elements and methylmercury were determined in the liver homogenate using instrumental neutron activation analysis, voltammetry, and cold vapor atomic absorption spectroscopy. The preparation and analysis of these two tissue materials are part of the development of marine mammal tissue reference materials.