Ueber Elementaranalyse von Kohlen

Ohne Zusammenfassung(Mittheilung aus dem Chemisch-technischen Institut der Technischen Hochschule zu Karlsruhe.)     

Time-resolved streak camera system with solid state laser and optical parametric generator in different spectroscopic applications

Apparatus to study time-evolution of emission spectra over very wide time and spectral range is described. Excitation part of the equipment consists of solid state Nd:YAG laser and optical parametric generator. The heart of the detection system consists of spectrograph and streak camera. The significance of optics and electronics built in the system for proper, fast and convenient measurements is underlined. The results of donor-acceptor energy transfer in a rigid polyvinyl alcohol matrix serve here as an example of application our equipment to study complex systems.     

Dissipative effects on internal gravity waves in geophysical fluids

Summary In the present paper we develop a systematic analysis of the dispersion and dissipation effects on internal gravity waves in fluids of geophysical interest. Dissipation induces a cut-off in the short wavelengths, leading to an admissible range of waves. Defining a suitable criterion for detection of waves, an observable wave range results, in which the frequency dispersion is nearly the same as for the inviscid case, whereas the amplitude is damped. The peculiar behaviour displayed by the dispersion relationship for Prandtl number equal to one is discussed.     

Cryoscopic and dynamic study of the molten system fluoroacetamide-sodium trifluoroacetate

The behavior of the molten system acetamide-electrolyte, including the peculiarity of the structure and the consequent relevant properties, such as the megavalue of the dielectric constant, was reported earlier. The probable structure is a micellar system composed of salt micelles dispersed in an amorphous solvent. The present paper reports measurements in a related system: fluoroacetamide-sodium trifluoroacetate. The phase diagram, the ultrasonic absorption of both longitudinal and shear waves, and the longitudinal relaxation time of the nuclear magnetic momentum were measured at different temperatures. The most importnat result was thatT ₁ (NMR relaxation time) on the¹⁹F nucleus shows that the amide and salt participate in different environments. The amide environment is less rigid; this proves that the system must be considered microheterogeneous. Moreover, the present system exhibited: 1) a less extended concentration area where supercooling phenomena occur; 2) a much broader curve of the real part of the mechanical impedance versus frequency; 3) a higher bulk viscosity in comparison with the CH₃CONH₂?CF₃COONa supercapacitive system.     

Polynomial bounds for Large Bernoulli sections of ℓ 1 N

We present a quantitative form of the result of Bai and Yin from [2], and use to show that the section of ℓ ₁ ^(1+δ)n spanned byn random independent sign vectors is with high probability isomorphic to euclidean with isomorphism constant polynomial in δ⁻¹. Partially supported by BSF grant 2002-006. Supported by the National Science Foundation under agreement No. DMS-0111298. Supported in part by the Israel Science Academy.     

Zum Nachweis von Baryumverbindungen in Vergiftungsf?llen

Ohne Zusammenfassung     

Characterization and activity of sonochemically-prepared BSA microspheres containing Taxol--an anticancer drug

Proteinaceous microspheres of BSA (Bovine Serum Albumin) containing an anticancer drug, Taxol (paclitaxel) were fabricated using a sonochemical procedure and then assayed for chemical and biological activity. The sonochemical reaction did not compromise the drug, which became encapsulated in the BSA microspheres. The amount of the anticancer drug in the microspheres was determined by HPLC. Anticancer activity of the proteinaceous microspheres encapsulating the Taxol was tested on Mouse Multiple Myeloma cell line MPC-11. The influence of the Taxol microspheres on the cancer cells was different from pristine Taxol. It was found that Taxol in combination with the organic solvent causes the death of cancer cells.     

Effects of Periodic Excitation on the Flow Around a D-Shaped Cylinder at Low Reynolds Numbers

The baseline and forced flow around a bluff body with semi-elliptical D-shape was investigated by solving the 2D Navier–Stokes equations at low Reynolds numbers. A D-shape rather than the canonic circular-cylinder was selected due to the fixed separation points in the latter, enabling to study a pure wake rather than boundary-layer control. The correlation between Strouhal and Reynolds numbers, the mean drag, the lift and drag oscillations vs. the Reynolds number and wake structure were investigated and compared to experimental and numerical data. Effects of open-loop forcing, resulting from the influence of zero-mass-flux actuators located at the fixed separation points, were studied at a Reynolds number of 150. Fluidic rather than body motion or volume forcing was selected due to applicability considerations. The motivation for the study was to quantify the changes in the flow field features, as captured by Proper Orthogonal Decomposition (POD) analysis, due to open-loop forcing, inside and outside the “lock-in” regime. This is done in order to evaluate the suitability of low-order-models based on POD modes of this changing flow field, for future feed-back flow control studies. The evolution of the natural and the excited vortices in the Kármán wake were also investigated. The formation and convection regions of the vortex evolution were documented. It was found that the forcing causes an earlier detachment of the vortices from the boundary-layers, but does not affect their circulation or convection speeds. The results of the POD analysis of the near-wake flow show that the influence of the bluff body shape (“D”-shaped versus circular cylinder) on the baseline POD wake modes is small. It was found that the eigenfunctions (mode-shapes) of the POD velocity modes are less sensitive to slot excitation than the vorticity modes. As a result of the open-loop excitation, two types of mode-shape-change were observed: a mode can be exchanged with a lower-energy mode or shifted to a low energy level. In the latter case, the most energetic mode becomes the “actuator” mode. The evolution of one-slot excitation on still fluid (“Synthetic jet”) was studied and compared to published data and to “actuator” modes with external flow present. Based on the current findings, it is hypothesized that the cross-flow velocity POD modes are suitable for feedback control of wake flow using periodic excitation, due to their low sensitivity to the excitation as compared to the streamwise velocity or vorticity modes.     

Synthesis and photoelectrochemical properties of cyclometallated ruthenium(II) complex

A new ruthenium complex, (4-carboxy-1,10-phenantroline-7-carboxylate)(4,7-dicarboxy-1,10-phenantroline)(2-phenylpyridino-²C,N) ruthenium(II), was obtained for the application as a sensitizer in photoelectrochemical converters (PECC). Electrochemical and spectral characteristics of the compound were studied. It was found that the illumination of PECC with AM 1.5 100 mW/cm² solar spectrum simulator provides short circuit current density of 3.9 mA cm^?2 and broken circuit voltage of 0.47 V. PECC efficiency is 1.4% at fillfactor 76%. The lifetimes of charge carriers (electrons) and their transit time determined by modulation spectroscopy were found to be 28 and 4 ms, respectively.     

Conformational energetics of interpolyelectrolyte complexation between ι-carrageenan and poly(methylaminophosphazene) measured by high-sensitivity differential scanning calorimetry

The interaction of poly(methylaminophosphazene) hydrochloride (PMAP·HCl) of varying degrees of ionization (f) with the potassium salt of ι-carrageenan was studied by high-sensitivity differential scanning calorimetry at a KCl concentration of 0.15 M, which is included for the purpose of stabilizing the helix conformation of the polysaccharide up to 55 °C. The conditions of strong (pH 3.8, I = 0.15), moderate (pH 7.4, I = 0.15), and weak (pH 7.4, I = 0.25) electrostatic interactions of the polyelectrolytes were considered. The thermodynamic parameters of the helix-coil transition of ι-carrageenan were determined as a function of the polycation/polyanion ratio. We show that the interpolyelectrolyte reaction between PMAP·HCl and ι-carrageenan results in a complete unfolding of the polysaccharide helix under conditions of strong electrostatic interaction and increases its stability under conditions of medium and weak electrostatic interactions. The formation of stoichiometric PMAP-carrageenan interpolyelectrolyte complexes proceeded via a cooperative mechanism at pH 3.8 (f = 0.5) and pH 7.4 (f = 0.2) at an ionic strength of 0.15. In contrast, the complexation at pH 7.4 and an ionic strength of 0.25 could be considered to be a consecutive competitive binding of charged units of poly(methylaminophosphazene) to the oppositely charged polysaccharide matrix in the helix or coil conformation. Binding constants of the polycation to the helix and coil forms of ι-carrageenan were estimated. They revealed a preferential binding of the polycation to the helix form of the polysaccharide.