Drop profile analysis tensiometry with drop bulk exchange to study the sequential and simultaneous adsorption of a mixed β-casein /C12DMPO system

The formation of mixed protein/surfactant adsorption layers is studied by the drop profile analysis tensiometry equipped with a special tool for drop volume exchange during experiments. This arrangement allows investigating in the traditional way by simultaneous adsorption from a mixed solution and also by a subsequent adsorption of the protein followed by surfactant. The experiments are performed for β-casein as the protein in the presence of different amounts of the non-ionic surfactant C₁₂DMPO. The surface layers formed via the two routes show similar equilibrium surface properties. However, the dynamics of desorption of the protein complexes into the pure buffer solution deviate significantly, which is explained by the different locations of the protein/surfactant interaction. Although in both cases the complex formation is based on hydrophobic interaction, the accessibility of the hydrophobic parts of pre-adsorbed proteins due to unfolding is more favourable by the surfactant than in the solution bulk. Therefore, the amount desorbed from surface layers formed from mixed solutions is significantly less as compared to the displacement of proteins by subsequently injected surfactants interacting at the surface.     

Fourier holograms recorded and decoded in polychromatic light

This paper describes a recording and reconstruction method applied to two-dimension Fourier holography, in which the illumination at the recording stage is spatially coherent and temporally incoherent. The various chromatic components of the information to be recorded in the hologram are spread along a direction orthogonal to the entrance slit of a spectroscope that behaves as scanning pupil performing a chromatic coding. The message, both spatially and temporally coded, can be reconstructed by using a conventional process, the light source being still polychromatic.     

Ladder network characterization and Fibonacci numbers

Summary This paper illustrates a new method, proposed by the authors, which allows the direct determination of ladder networks characteristics, from both a numerical and a symbolic point of view, once the number of cells and their circuit elements are known. In particular, using a single treatment for the solution of all the possible ladder networks, the transfer function, node voltages and branch currents, Thevenin's model, input and output impedance, signal-to-noise ratio, transmission, quadrupole and scattering matrices are determined. In the particular case in which the longitudinal and transversal impedances are equal, these electrical characteristics are strictly and surprisingly related to Fibonacci numbers. Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction.     

A comparison of analytical methods for the quantification of a reactive β-cyclodextrin fixed onto cotton yarns

Cotton yarns bobbins were treated in a water bath with different concentrations of a reactive β-cyclodextrin derivative. To quantify the amount of cyclodextrin fixed on the fiber different analytical methods were tested but none of them was reliable enough in the concentration range under investigation. Therefore, a new analytical method, fast and effective, was developed. From the measurement of cyclodextrin bath exhaustion, the amount of cyclodextrin chemically fixed and that physically adsorbed on the textile substrate was estimated. Two washing cycles were carried out to investigate the cyclodextrin washing fastness.     

Preparation and characterization of hybrid nanoparticles based on chitosan and poly(methacryloylglycylglycine)

CeO₂–MnO _x composites possessing rod-like morphology (fixed mole proportion of Ce/Mn) were synthesized through hydrothermal method and chosen as supporters to load PdO nanoparticles (PdO/Ce _x Mn_1–x ). The size of loaded PdO nanoparticles is about 2 nm. The catalytic behaviors of supported catalysts were examined through the complete catalytic oxidation of benzene. The results illustrated that the activities of supported catalysts were enhanced greatly as compared to unsupported, and the completely conversion temperature of benzene was reduced to ca. 250 °C. The effect of noble metal species (PdO) addition on the catalytic property and crystal structure of composites was researched in detail. The data revealed that the interaction between PdO and supporter, and intrinsic properties of supporter resulted in the enhancement of catalytic abilities.     

Novel transformations in the quassin series

A series of remarkable rearrangement reactions involving (1β,9β)-1-methoxypicras-11-en-16-one and related derivatives are described.     

Novel routes to Cu(salicylaldimine) covalently bound to silica: combined pulse EPR and in situ attenuated total reflection-IR studies of the immobilization

Several novel routes for the immobilization of modified Cu(salicylaldimine) complexes on commercially available silica are described. New pulse electron paramagnetic resonance (EPR) and electron-nuclear double resonance sequences, which provide more detailed information than that available previously, in combination with continuous wave EPR, allow a definitive assignment of the geometry at the copper center in the immobilized Cu(salicylaldimine). Immobilization of the modified Cu(salicylaldimine) on silica was followed in situ by monitoring the intensity of the characteristic free- and metal-coordinated imine bands as a function of time using attenuated total reflectance IR spectroscopy. On the basis of these studies, the outcome of the Schiff base condensation of Cu-bis(salicylaldehyde) with gamma-aminopropyl-modified silica gel is shown to provide immobilized trans-O(2)N(2)- and O(3)N-coordinated immobilized Cu(salicylaldimine)-type compounds. In addition, trans-O(2)N(2)- or O(3)N-coordinated copper centers are selectively prepared on silica by controlling the aminopropyl modifier loading, thus opening a route to compounds not available by conventional synthesis. The O(3)N-coordinated Cu(salicylaldimine)-type compound on silica was investigated as a precursor for the synthesis of a tethered chiral Cu(salicylaldimine) via reaction of the coordinated carbonyl group with (R)-(+)-alpha-methylbenzylamine. Supported Cu(salicylaldimine) was also prepared via the immobilization of the appropriate silylethoxy-modified homogeneous precursor on silica gel. Precursors and silica-supported Cu(salicylaldimine) materials have been fully characterized. Comparisons are drawn with related Cu(salicylaldimine) immobilized in silica aerogels.     

New method for separation and determination of denatured caseins by hydrophobic interaction chromatography

A new method for the separation of denatured alpha-, beta- and kappa- caseins by hydrophobic interaction chromatography (HIC) is proposed. The method is based on an easy solubilization of commercial and real samples by 4.0 M guanidine thiocyanate (GdmSCN) and elution on a TSK-Gel(R) Phenyl-5PW column (TosoHaas) in the presence of 8.0 M urea in the mobile phase. The procedure, applied to commercial caseins and to real, raw samples (whole milk powder and fat-free yoghurt) is not expensive, it requires common high performance liquid chromatography (HPLC) instrumentation and allows the separation of caseins also in the presence of whey proteins. Quantitative results on the analysis of alpha-, beta- and kappa-caseins in real samples are also reported.