Chiral separation of amino-alcohols using extractant impregnated resins

The performance of extractant impregnated resin (EIR) technology for chiral separation of amino-alcohols has been investigated. Phenylglycinol was selected as an archetype model enantiomer and azophenolic crown ether was used as a versatile enantioselective extractant. 1-Phenyloctane was selected as a suitable solvent for this application because of its very low solubility in water. The extraction system was first evaluated by liquid-liquid equilibrium experiments. It was shown that crown ether dissolved in 1-phenyloctane has an intrinsic selectivity of 11.5. However, due to very low solubility of phenylglycinol in 1-phenyloctane, the overall capacity of the crown ether solution in 1-phenyloctane is limited. The extractant solution was immobilized in macroporous polypropylene particles. Competitive sorption isotherms were obtained from batch experiments and successfully described with a predictive model based on the complexation constants and partitioning ratios, either obtained from literature or from independent experiments. The equilibrium selectivity of these EIRs approaches the intrinsic selectivity for low phenylglycinol concentrations. The dynamic behaviour and stability of the system were examined in column experiments. Breakthrough profiles as well as the elution curves of the R enantiomer are less sharp than those of the S enantiomer proving that the R enantiomer is strongly retained on the column. Separation of phenylglycinol enantiomers is favoured by using lower feed flow rates. The column was regenerated by water with only atmospheric carbon dioxide dissolved which proved to be sufficient. After several cycles the breakthrough profiles remain unchanged suggesting that these EIRs will be sufficiently stable.     

Multispectral imaging of continuum emission for determination of temperature and density profiles inside implosion plasmas

In inertial confinement fusion experiments, implosion of a cryogenic hydrogen isotope-filled capsule produces a plasma with a high-temperature, low-density core (the hot spot) surrounded by a low-temperature, high-density main fuel layer. Experimental measurements of temperature and density profiles in the hot spot are critical for implosion diagnosis. In this paper, we propose a simple technique for measuring core temperature and density profiles in cryogenic implosion plasmas. This technique uses absolutely calibrated continuum emission spectroscopy coupled with two-dimensional imaging to allow temperature and density profiles to be measured directly. We develop the technique analytically, and validate it using synthetic data and hydrodynamics simulation results. We find that the technique should be sufficiently accurate to measure central temperatures and densities to better than 20%. The technique may also find application to the diagnosis of other types of plasmas.     

Kinetic derivation of the second virial coefficient for a quantum gas

A kinetic equation has been proposed earlier for an inhomogeneous quantum dilute gas obeying Boltzmann statistics. We show here that it leads to the correct equilibrium properties of the gas by computing the second virial coefficient as it can be deduced from the trace of the pressure tensor and by checking the result with the value deduced from various approaches.     

Mesons in the Eguchi Kawai model

Fermions in the fundamental representation of theSU(N) gauge group are incorporated into the Eguchi Kawai reduction scheme. The proof for the equivalence of reduced and extended theories is given. This equivalence can be used, to calculate chiral condensate and meson propagators from the fermion matrix of a partially reduced TEK model.     

Dominated variation and related concepts and Tauberian theorems for Laplace transforms

Some Abelian and Tauberian theorems are proved under conditions of dominated variation and related concepts. For example U is dominatedly varying if and only if its Laplace-Stieltjes transform is dominatedly varying.     

The role of linear electric field effects in halogen induced 13C chemical shifts in cyclohexanes and methylenecyclohexanes

The ¹³C NMR chemical shifts of methylenecyclohexane at low temperature are compared with those of 4-chloro- and 4-bromo-methylenecyclohexane under the same conditions. It is concluded that the halogen induced shift differences at the double bond are to be ascribed largely to linear electric field (LEF) effects. At the same time, doubt is expressed concerning similar explanations for C-4 in halo-substituted cyclohexanes. The large influence of using different values of longitudinal bond polarizabilities is demonstrated. Finally, some remarkable long-range shift effects on double bonds are described for geranyl chloride and geranyl bromide.     

Ionic liquids as silica deactivating agents in gas chromatography for direct analysis of primary amines in water

Analysis of primary amines in aqueous samples remains a challenging analytical issue. The preferred approach by gas chromatography is hampered by interactions of free silanol groups with the highly reactive amine groups, resulting in inconsistent measurements. Here, we report a method for direct analysis of aliphatic amines and diamines in aqueous samples by gas chromatography (GC) with silanol deactivation using ionic liquids (ILs). ILs including trihexyl(tetradecyl)phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (Cyphos IL-104), 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [pmim][Tf(2)N] and N″-ethyl-N,N,N',N'-tetramethylguanidinium tris(pentafluoroethyl)trifluorophosphate [etmg][FAP] were tested as deactivating media for the GC liner. Solutions of these ILs in methanol were injected in the system prior to the analysis of primary amines. Butane-1,4-diamine (putrescine, BDA) was used as a reference amine. The best results were obtained using the imidazolium IL [pmim][Tf(2)N]. With this deactivator, excellent reproducibility of the analysis was achieved, and the detection limit of BDA was as low as 1mM. The applicability of the method was proven for the analysis of two different primary amines (C4-C5) and pentane-1,5-diamine.     

Neutron reflectometry on Co-Cr layers

Polarized neutron reflection experiments were performed on a thin in-plane magnetized Co-Cr layer deposited on a quartz substrate. Data taken at a low magnetic field ( 0.1 T) clearly indicate the existence of an initial layer at the substrate side, whereas data at saturation ( 0.7 T) are consistent with a rather homogeneous magnetization.     

The dynamic calibration of a hot wire by means of a sound wave

Hot wires of various design, operated by the constant resistance method, were calibrated by means of a plane sound wave of 2500 Hz. This is achieved by locating a small open resonance tube axially in a homogeneous incompressible airflow. Its third harmonic is excitated by superimposing a coaxial, damped, progressive, plane wave on the main airstream. The hot wire to be calibrated is situated in an anti-node of the particle velocity. The amplitude at this station is known from the pressure gradient of the standing wave measured at two small holes in the wall by a probe microphone. This device in turn is calibrated in a specially developed “pistonphone”. Numerical results of the diverse designs are communicated; an absolute accuracy of ±2% is achieved.     

A new perturbative approach for the anharmonic oscillator

A new perturbative approach is presented and applied to the anharmonic oscillator. Estimating the large-order behaviour by means of the Lipatov method, the new perturbation expansion turns out to be convergent for the partition function at non-zero temperature. Although the new perturbation expansion is not convergent for the ground-state energy, it nevertheless provides accurate approximations, even in situations which cannot be treated by standard perturbation techniques, like the strong coupling regime.