Spectroscopic study of plasmons in ion-irradiated single-walled carbon nanotubes

The electronic structure of single-walled carbon nanotubes was experimentally investigated using x-ray photoelectron spectroscopy, reflection electron energy-loss spectroscopy, and Auger electron spectroscopy. A shake-up satellite structure observed near the C 1s core-level lines in the x-ray photoelectron spectra at high binding energies in the range 284–330 eV due to excitation of π and π + σ plasmons was studied. The effect of irradiation by 1-keV argon ions on the shape of the spectra was analyzed. The shape of the C 1s satellite spectra was found to be sensitive to Ar⁺ irradiation in the electron energy loss range 10–40 eV corresponding to excitation of π + σ plasmons. Auger spectroscopy revealed the presence of argon on the surface of ion-irradiated samples. The argon content increased to ～4 at. % with increasing irradiation dose. An analysis of the results obtained and their comparison with the data available in the literature led to a qualitative conclusion that the bond angles of the carbon atoms making up the walls of single-walled carbon nanotubes are distorted at sites exposed to Ar⁺ irradiation.     

On the role of mechanical effects during dynamic fatigue of PbTiO3 single crystals

The details of the mechanical effects (twinning and microcracking) are clarified at various stages of dynamic fatigue of PbTiO₃ crystals using a polarization microscope and selective etching.     

Possibility of observing chiral-symmetry effects in ferromagnetic nanoparticles

The statistics of left-and right-handed vortical magnetization states in a system of submicron-sized ferromagnetic disks is studied experimentally. Lattices of elliptic cobalt particles with a planar size of 750 × 450 nm and a thickness of 25 nm were formed using high-resolution electronic lithography. To visualize the magnetization distributions in the disks, magnetic force microscopy was used. The experimental results indicate the conservation of magnetic chiral symmetry in cobalt ferromagnetic particles of the above size and shape.     

4-(Isoindolin-5-yl)amino-4-oxobutyryl-β-alkoxyphenyl-β-alanines, new RGDF mimetics. Synthesis, affinity to fibrinogen receptors, antiaggregatory properties, and their correlation with the hydrophobicity

A new series of RGDF mimetics, derivatives of 4-(isoindolin-5-yl)amino-4-oxobutanoic acid, was synthesized. The compounds obtained inhibit efficiently the thrombocytes aggregation in experiments in vitro; their biological targets are fibrinogen receptors. The antiaggregatory activity and the affinity correlate with the hydrophobicity of the compounds.     

Preparation and mechanical properties of layers made of recombinant spider silk proteins and silk from silk worm

Layers of recombinant spider silks and native silks from silk worms were prepared by spin-coating and casting of various solutions. FT-IR spectra were recorded to investigate the influence of the different mechanical stress occurring during the preparation of the silk layers. The solubility of the recombinant spider silk proteins SO1-ELP, C16, AQ24NR3, and of the silk fibroin from Bombyx mori were investigated in hexafluorisopropanol, ionic liquids and concentrated salt solutions. The morphology and thickness of the layers were determined by Atomic Force Microscopy (AFM) or with a profilometer. The mechanical behaviour was investigated by acoustic impedance analysis by using a quartz crystal microbalance (QCMB) as well as by microindentation. The density of silk layers (d<300 nm) was determined based on AFM and QCMB measurements. At silk layers thicker than 300 nm significant changes of the half-band-half width can be correlated with increasing energy dissipation. Microhardness measurements demonstrate that recombinant spider silk and sericine-free Bombyx mori silk layers achieve higher elastic penetration modules E_EP and Martens hardness values H_M than those of polyethylenterephthalate (PET) and polyetherimide (PEI) foils.     

Topology of N-Ethylmaleimide in normal human erythrocyte membrane

Normal human, hemoglobin free erythrocyte ghosts were labelled with¹⁴C–N-Ethylmaleimide and incubated at two different temperatures 4°C and 37°C. Gel electrophoresis, autoradiography and nuclear scintillation counting techniques were used in analysing which proteins were labelled. The results of the experiments with incubation at 4°C and 37°C indicated that 35% of the NEM was associated with spectrin and 50% was bound to spectrin- actin complex.