Zur argentometrischen Wertbestimmung von Theobromino-natrium salicylicum

Analytical and Bioanalytical Chemistry -     

Proteomic analysis of chicken eggshell cuticle membrane layer

The eggshell is a barrier that plays an important role in the defense of the egg against microbial and other infections; it protects the developing bird against unfavorable impacts of the environment and is essential for the reproduction of birds. The avian eggshell is a complex structure that is formed during movement along the oviduct by producing a multilayered mineral-organic composite. The extractable proteins of avian eggshells have been studied extensively and many of them identified, however, the insoluble (non-extractable) proteins have been sparsely studied. We studied the EDTA-insoluble proteinaceous film from the cuticle layer of eggshell. This film consists of three main areas: spots (cca 300 μm diameter), blotches (small spots with diameter only tens of μm), and the surroundings (i.e., the area without spots and blotches) where spots contain a visible accumulation of pigment. These areas were cut out of the membrane by laser microdissection, proteins were cleavaged by trypsin, and the peptides were analyzed by nLC/MS (Q-TOF). This study has identified 29 proteins and a further eight were determined by less specific “cleavage” with semitrypsin. The relative abundances of these proteins were determined using the exponentially modified protein abundance index (emPAI) where the most dominant proteins were eggshell-specific ones, such as ovocleidin-17 and ovocleidin-116. Individual areas of the cuticle membrane differ in their relative proportions of 14 proteins, where significant differences between the three quantification criteria (direct, after normalization to ovocledin-17, or to ovocledin-116) were observed in four proteins.     

Calorimetric study of melts in the system KF - K2TaF7

Enthalpy increment measurements on melts in the system KF-K₂TaF₇ were carried out by drop calorimetry at temperatures between 298 K and 1063, 1103 and 1143 K for selected compositions. Heat capacities of the melted mixtures and enthalpies of mixing have been determined. Careful calorimetric experiments showed small but distinct non-ideality of the melt. The molar heat capacity of melt exhibits small positive divergence from additivity. The molar enthalpy of mixing shows negative deviation from ideality which decreases with increasing temperature. The thermal effect at mixing was assigned predominantly to association reactions producing more complex fluorotantalate anions. The formation of complex anions with lower coordination number of Ta may not be excluded.      

Quantitative analysis of three phases of high-density polyethylene with 2D time-domain proton NMR

With two-dimensional time-domain NMR analysis in the proton spin rotating frame, three phases are identifiable in the solid polyethylene. The major proton magnetization fraction is due to the polymer's crystalline region, where the motion is least isotropic and slowest. A magnetization fraction with intermediate relaxation rate is also intermediate in magnitude. This component is proposed to comprise chain loops on the surfaces of crystallites and effectively entangled chain segments. The most mobile fraction, which is most liquid-like with a T₂ of near 1 ms at 120°C, is also the smallest. It is proposed that it is due to polymer chains in the amorphous phase. In the crystalline phase the chain motion is an unexpectedly effective relaxation mechanism at ∼50 KHz. This process, which involves propagation of a twisted region along the crystallite, as has been suggested before, is either not present in the other two phases of the HDPE or is less efficient because of the lower polymer density. The activation energies for the crystalline, intermediate and amorphous phases are estimated to be 34 ± 3, 13 ± 3, and 8 ± 2 Kcal/mol, respectively. The frequencies of the relaxation process at 120°C are 43 KHz, 350 KHz, and 1.5 MHz, respectively. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 2551–2558, 1997     

Study of thermal recrystallisation in Si implanted by 0.4-MeV heavy ions

A Si crystal layer on SiO₂/Si was implanted using 0.4-MeV Kr⁺, Ag⁺, and Au⁺ at ion fluences of 0.5 × 10¹⁵ to 5.0 × 10¹⁵ cm⁻². Subsequent annealing was performed at temperatures of 450° and 800° for 1 hour. The structural modification in a Si crystal influences ion beam channelling phenomena; therefore, implanted and annealed samples were investigated by Rutherford backscattering spectrometry under channelling (RBS-C) conditions using an incident beam of 2-MeV He⁺ from a 3-MV Tandetron in random or in aligned directions. The depth profiles of the implanted atoms and the dislocated Si atom depth profiles in the Si layer were extracted directly from the RBS measurement. The damage accumulation and changes in the crystallographic structure before and after annealing were studied by X-ray diffraction (XRD) analysis. Lattice parameters in modified silicon layers determined by XRD were discussed in connection to RBS-C findings showing the crystalline structure modification depending on ion implantation and annealing parameters.     

Antibacterial properties of Ag-doped hydroxyapatite layers prepared by PLD method

Thin hydroxyapatite (HA), silver-doped HA and silver layers were prepared using a pulsed laser deposition method. Doped layers were ablated from silver/HA targets. Amorphous and crystalline films of silver concentrations of 0.06 at.%, 1.2 at.%, 4.4 at.%, 8.3 at.% and 13.7 at.% were synthesized. Topology was studied using scanning electron microscopy and atomic force microscopy. Contact angle and zeta potential measurements were conducted to determine the wettability, surface free energy and electric surface properties. In vivo measurement (using Escherichia coli cells) of antibacterial properties of the HA, silver-doped HA and silver layers was carried out. The best antibacterial results were achieved for silver-doped HA layers of silver concentration higher than 1.2 at.%.     

High energy Au+ ion implantation of polar and nonpolar ZnO—Structure modification and optical properties

The paper presents a study of 5-MeV energy Au⁺ ion implantation in polar c-plane (0001), nonpolar a-plane (11-20) and m-plane (10–10) ZnO crystallographic cuts using fluences of 5 × 10¹⁴ and 1 × 10¹⁵ cm⁻². The implanted samples were subsequently annealed in O₂ atmosphere at 600°C. It was shown that a-plane ZnO exhibited a lowest level of Zn sublattice disorder evidenced by Rutherford backscattering spectroscopy in channelling mode (RBS-C); in contrast, m-plane ZnO showed the highest disorder. The disorder in the Zn sublattice grew progressively in the subsurface as well as in the implanted layer in c-plane and m-plane ZnO, while a-plane has shown slight increase of disorder just in the implanted layer. Angular scans provided using RBS-C have shown the preservation of channelling effect in the subsurface layer in a-plane ZnO. On the contrary, the narrowed and shallow angular scan dips were seen in m-plane ZnO. Raman spectroscopy has shown significant O-sublattice disorder and O rearrangement mainly in a-plane and m-plane ZnO compared to c-plane. After ion implantation, the exciton-related luminescence band at 375 nm vanished almost completely, and the defect-related band ‘shifted’ to shorter wavelengths. Annealing has beneficial influence on near-band-edge (NBE) luminescence recovery, whereas deep-level-emission (DLE) luminesce has been shifted to lower wavelengths than appeared after implantation.