Alkalien

Ohne Zusammenfassung     

Two‐fold Bioorthogonal Derivatization by Different Formylglycine‐Generating Enzymes

Formylglycine‐generating enzymes are of increasing interest in the field of bioconjugation chemistry. They catalyze the site‐specific oxidation of a cysteine residue to the aldehyde‐containing amino acid C^α‐formylglycine (FGly). This non‐canonical residue can be generated within any desired target protein and can subsequently be used for bioorthogonal conjugation reactions. The prototypic formylglycine‐generating enzyme (FGE) and the iron‐sulfur protein AtsB display slight variations in their recognition sequences. We designed specific tags in peptides and proteins that were selectively converted by the different enzymes. Combination of the different tag motifs within a single peptide or recombinant protein enabled the independent and consecutive introduction of two formylglycine residues and the generation of heterobifunctionalized protein conjugates.     

A hybrid Finite Integration–Finite Volume Scheme

A hybridized scheme for the numerical solution of transient electromagnetic field problems is presented. The scheme combines the Finite Integration Technique (FIT) and the Finite Volume Method (FVM) in order to profit from the computational efficiency of the FIT while taking advantage of the superior dispersive properties of the FVM. The scheme is based on the longitudinal–transverse (LT) splitting of the discrete curl operator. The FIT is employed for discretizing the two-dimensional subproblem while the one-dimensional problem is discretized according to the FVM. The scheme offers benefits for the simulation of multiscale setups, where the size of the computational domain along one preferred direction is electrically much larger than along the others. In such situations, the accumulation of dispersion errors within hundreds of thousands of time steps usually deteriorates the solution accuracy. The hybrid scheme is applied in combination with adaptive mesh refinement, yielding an efficient scheme for multiscale applications.     

Quasi-solitons as nonstationary self-similar solutions of the Korteweg-de Vries-Burgers equation

The Korteweg-de Vries-Burgers equation (KdV-B) is studied analytically and numerically for weak dissipation in the nonstationary case (self-similar solutions). Starting the analytical study from the system (S) of two kinetic equations equivalent to KdV-B equation in the exact adiabatic approximation of a symmetrically damped solitary pulse, we renormalize this system by taking into account the asymmetry produced by the damping (tail) and obtain a simple mechanical picture describing qualitatively and quantitatively the properties of the tailed quasi-solitons: the leading pulse is described by an oscillation in a potential well, while the asymmetry is obtained from a transition between two nearby energy levels located at the top of the well. The superposition properties of the quasi-solitons are discussed in the adiabatic approximation, using a Bäcklund transformation directly deduced from system (S). All these analytical results are checked by the numerical study which shows in particular that the tail, once built, becomes completely disconnected from its “mother” soliton and behaves like noise.     

The settling of suspensions promoted by rigid buoyant particles

When substantial numbers of buoyant particles are mixed with a sedimenting suspension of heavy particles, the two types of solids undergo rapid lateral segregation from each other. Streams 3–5 mm in diameter containing the less populous species form and flow through a concentrated continuum suspension of the more populous species. This buoyancy driven convection results in greatly enhanced sedimentation rates. A theory is developed on the premise that streams move in plug flow with all resistance to motion confined to a thin lubricating layer at the strean-continuum interface. The model is compared with experimental data and is shown to account correctly for the effect of each system parameter on the observed settling rates.     

Laser-induced incandescence: Development and characterization towards a measurement of soot-volume fraction

Laser-Induced Incandescence (LII) occurs when a high-energy pulsed laser is used to heat soot to incandescent temperatures. Theoretical calculations predict and experimental tests demonstrate the resulting incandescence to be a measure of soot-volume fraction. Practical implementation of the technique is detailed by examining the spectral character, temporal behavior, and excitation-intensity dependence of the resulting thermal emission from the laser-heated soot in both premixed and diffusion flames. Spatial and temporal capabilities of LII are demonstrated by obtaining one- and two-dimensional images of soot-volume fraction via laser-induced incandescence in both types of flames.     

Analyse de la pyrolyse menagee du bois par un couplage TG-DSC-IRTF

This paper deals whith thermal degradation of wood at low pyrolysis temperature. Chemical modifications are investigated in order to explain the new properties of treated wood.

     

Die colorimetrische Aluminiumbestimmung mit Eriochromcyanin

Zusammenfassung Der colorimetrische Nachweis kleinster Aluminiummengen mit Eriochromcyanin wurde zu einer quantitativen Bestimmungsmethode für Al-Mengen von 5–100 erweitert.Es wurde festgestellt, daß der Al-Lack mit Eriochromcyanin dem Beerschen Gesetz gehorcht und daß sowohl oolorimetrische Versuchswie Vergleichsmessungen zu befriedigenden Ergebnissen führen.Die Abscheidung der Phosphorsäure wurde mit Li^. in alkalischer Lösung, die Trennung des Aluminiums von störenden Kationen wurde mit Natronlauge durchgeführt.Es wurde eine genaue Arbeitsvorschrift zur Bestimmung kleinster Aluminiummengen nach dieser Methode gegeben