Abbeugung des Lichts durch kolloide Lösungen

Ohne Zusammenfassung übersetzt von A. Siehr (Leipzig). Herrn Prof. H. E. Watson, D. Sc., F. I. C., M. I. Chem. E., m?chte ich an dieser Stelle meinen herzlichsten Dank für seine wertvolle Hilfe und Anleitung bei der Durchführung dieser Arbeit aussprechen.     

Incorporating Mathematics into the Science Program of Students Labeled “At‐Risk”

Twenty three at‐risk high school female students who had failed mathematics and science in a traditional school setting were the subjects of this study that integrated mathematics and science lessons over a period of four weeks. Using a combination of direct instruction, calculations, graphing, hands‐on projects, and discussion, the topic of mechanical advantage was studied, to find out how well students understood the topic. The study found that these students who initially knew very little about mechanical advantage, and who did not see any need to use mathematics in the study of science, indicated an increased understanding of mechanical advantage, and also seemed to realize that integrating mathematics and science enhanced learning.     

Determination of electrical and solar cell parameters of FTO/CuPc/Al Schottky devices

A Schottky structure is fabricated using CuPc sandwiched between fluorinated tin oxide (FTO) and aluminium electrodes. The electrical properties of the device are measured at room temperature. Permittivity of the device is calculated from capacitance measurements. The saturation current density, , diode ideality factor, n=3.02 and barrier height, are determined for the Schottky juction. Reverse bias versus is interpreted in terms of Schottky emission. Solar cell parameters are determined from the J-V characteristics. Power conversion efficiency, η of 0.0024% is obtained for the cell. Band gap energy of the material is determined from UV-visible absorption spectrum.     

Extending the biocatalytic scope of regiocomplementary flavin-dependent halogenase enzymes

Flavin-dependent halogenases are potentially valuable biocatalysts for the regioselective halogenation of aromatic compounds. These enzymes, utilising benign inorganic halides, offer potential advantages over traditional non-enzymatic halogenation chemistry that often lacks regiocontrol and requires deleterious reagents. Here we extend the biocatalytic repertoire of the tryptophan halogenases, demonstrating how these enzymes can halogenate a range of alternative aryl substrates. Using structure guided mutagenesis we also show that it is possible to alter the regioselectivity as well as increase the activity of the halogenases with non-native substrates including anthranilic acid; an important intermediate in the synthesis and biosynthesis of pharmaceuticals and other valuable products.     

Improvement of some pharmaceutical properties of mycophenolate mofetil (MMF) by para sulphonatocalix[4]resorcinarene inclusion complex

As a part of our investigations to unfold the chemistry of calixresorcinarene, we have focused on the formation of inclusion complex of a poorly soluble (43 μg ml^?1 at pH 7) drug mycophenolate mofetil (MMF) an immunosuppressive agent and an inosine monophosphate dehydrogenase (IMPDH) inhibitor with para sulphonatocalix[4]resorcinarene (PSC4R). The complete complexation of the drug was achieved after 48 h of stirring with para sulphonatocalix[4]resorcinarene(PSC[4]R) in water and evaporation of water yield the solid complex. The interaction between para sulphonatocalix[4]resorcinarene(PSC[4]R) and MMF in solid state inclusion complexes was accomplished by aqueous phase solubility studies, Thermal Analysis, HPLC, PXRD, FT-IR, and UV–Vis spectroscopy. The results of the phase solubility experiments are in good conformity to signify the formation of 2:1 PSC4R: MMF complexes. The purpose of this study was to enhance solubility and resulting in high dissolution rate and bioavailability of this essentially water insoluble drug. The results of the in vivo study shows that there is a remarkable change in the toxicity of the pure drug MMF and complex did not produce any mortality up to 2200 mg kg^?1.     

Growth rate predictions of single- and multi-mode Richtmyer�CMeshkov instability with reshock

The single- and multi-mode Richtmyer–Meshkov instabilities (RMI) with reshock are numerically analyzed in two- and three-dimensional domains. Four different types of air/SF ₆ interface shapes are investigated in a shock tube configuration, and the predicted post-reshock growth rates are compared with available empirical models of Mikaelian’s (Physica D 36(3):343–347, 1989) and Charakhch’an’s (J Appl Mech Tech Phys 41(1):23–31, 2000). The simulation of 3D multi-mode RMI shows good agreement with a past experimental study, but other interface types (2D single-mode, 2D multi-mode and 3D single-mode) result in different growth rates after reshock. Parametric studies are therefore performed to investigate the sensitivities of the post-reshock growth rates to model the empirical parameters. For single-mode RMI configurations, the interface shape is found to be only a weak function of the post-reshock growth rate, as also predicted by previous reshock models. The post-reshock growth rate shows a linear correlation to the velocity jump due to reshock; however, it is only about a half of the prediction of Charakhch’an’s model even though the growth before reshock compares well with pre-reshock models. The 3D single-mode post-reshock RMI growth rate is nearly 1.6 times larger than the 2D single-mode RMI. The parametric studies of multi-mode RMI show two distinctly different growth rates depending on the mixing conditions at reshock. If the interface remains sharp at the time of reshock, the post-reshock growth rate is as large as the single-mode cases. However, if the interface is mixed due to non-linear interactions of bubbles and spikes, the growth rates becomes slow and independent of the interface shapes. Overall, this study provides new insights into the flow features of reshocked RMI for different initial perturbation types.     

Third-order elastic constants and pressure derivatives of the second-order elastic constants of β-tin

The second- and third-order elastic constants and pressure derivatives of second-order elastic constants of tetragonal β-tin have been obtained using the deformation theory. The strain energy density derived using the deformation theory is compared with the strain dependent lattice energy obtained from the elastic continuum model approximation to get the expressions for the second- and third-order elastic constants. Higher order elastic constants are a measure of the anharmonicity of a crystal lattice. The 12 non-vanishing third-order elastic constants and the six pressure derivatives of the second-order elastic constants in tetragonal β-tin are obtained in the present work and are compared with the available experimental values. The second-order elastic constant C₃₃ obtained in the present study is in reasonable agreement with the experimental values. The third-order elastic constants are generally one order of magnitude greater than the second-order elastic constants as expected of a crystalline solid. The third-order elastic constant C₃₃₃ is higher in magnitude than all other values. This shows a greater anharmonicity of β-tin along the c-axis direction of the crystal.     

The multicomponent reaction of dimethoxycarbene, dimethyl butynedioate and electrophilic styrenes: an unprecedented synthesis of highly substituted cyclopentenone acetals

The zwitterionic species generated by the addition of dimethoxycarbene to dimethyl butynedioate is trapped by arylidenemalononitrile to yield cyclopentenone derivatives.     

Ortho-tellurated derivatives of some arylamines and imines

A range of novel bi-, tri- and multidentate organotellurium ligands containing Te and N donor atoms and their derivatives have been synthesised. The synthetic strategy involves telluration of orthochelating, monoanionic substrates derived from the following arylamines: N,N-dimethylbenzylamine, (S)-(-)-N,Ndimethyl-1-phenethylamine, N,N-dimethylnaphthylamine, (N,N-di-methylaminomethy l) ferrocene, tricarbony1(N, N-dimethylbenzenemethanamine) chromium and 2-(3-thienyl)-pyridine. In addition novel chiral hybrid Schiff base ligands have been prepared by the condensation reaction of bis(o-formylphenyl) telluride ando-butyltellurobenzaldehyde with (R)-(+)-l-phenethylamine and (1R, 2S)-(-)-norephedrine.