Persönlichkeit 2.0

Online Social Networks (OSNs) wie MySpace, Facebook und StudiVZ sind inzwischen zu einem wichtigen Bestandteil des allt?glichen Miteinanders geworden. Entgegen der weit verbreiteten Meinung vermitteln Profile in OSNs kein verf?lschtes, selbstidealisiertes, sondern ein sehr genaues Bild von der Pers?nlichkeit der Profilbesitzer. Dies k?nnte ein wichtiger Grund für die Beliebtheit sozialer Netzwerke sein: Sie bieten eine Plattform für reale soziale Interaktionen und erm?glichen den Ausdruck der eigenen Pers?nlichkeit. Implikationen für den Datenschutz in OSNs werden diskutiert.     

ELECTROPORATION: BIO-ELECTROCHEMICAL MASS TRANSFER AT THE NANO SCALE

This article provides a brief review of the field of electroporation and introduces a new microdevice that facilitates studies to test theories, gain understanding, and control this important biomedical technology. Electroporation, a bio-electrochemical process whose fundamentals are not yet understood, is a means of permeating the cell membrane by applying a voltage across the cell and forming nano-scale pores in the membrane. It has become an important field in biotechnology and medicine for the controlled introduction of macromolecules, such as gene constructs and drugs, into various cells. It is viewed as an engineering alternative to biological techniques for the genetic engineering of cells. To study and control electroporation, we have created a low-cost microelectroporation chip that incorporates a live biological cell with an electric circuit. The device revealed an important behavior of cells in electrical fields. They produce measurable electrical information about the electroporation state of the cell that may enable precise control of the process. The device can be used to facilitate fundamental studies of electroporation and can become useful in providing precise control over biotechnological processes.     

Structure and composition of aluminum oxide films in contact with the liquid In-Ga eutectic

The oxide layers on the surface of aluminum metal and the aluminum alloys AD-1 and A-5 have been studied by attenuated total reflection infrared spectroscopy. The Al-O and Al-OH surface vibrational modes and A-O modes of the AlO₄ and AlO₆ groups have been identified. The structural inhomogeneity of the surface oxide layers is shown to contribute to their disruption when the sample is brought into contact with the liquid In-Ga eutectic. In situ scanning electron microscopy and X-ray microanalysis have been used to follow the dynamics of oxide layer disruption and the morphological and compositional changes in the eutectic alloy and the surface layer of aluminum.     

Intermetallide catalysts for hydrogen storage on the basis of reversible aromatics hydrogenation/dehydrogenation reactions

New efficient intermetallide catalysts for hydrogen storage in reversible processes of aromatics hydrogenation and naphthene dehydrogenation were studied. These catalysts provide an enhanced activity in the dehydrogenation of saturated organic molecules, with no side reactions like cracking, hydrogenolysis, ring opening, or coke formation occurring on these catalysts. The use of intermetallides provides some hydrogen storage capacity in the low-temperature region, while their catalytic activity in the dehydrogenation affords the hydrogen supply in the high-temperature range.     

The microstructure of composite cermet coatings produced by carbo-vibroarc surfacing

The results of investigation of the microstructure of composite coatings produced by carbo-vibroarc surfacing using cermet pastes are presented. It is shown that the composite cermet coating consists of two zones – the main and transition. The main zone of the coating contains the Fe₂B hardening phase with nickel and chromium atoms implanted in the crystal lattice of the phase. The zone is situated in the matrix of the solid solution of iron and nickel Ni₃Fe. The transition zone of the coating is formed by the mutual diffusion of the coating and the substrate and consists of the (Fe, Ni)₂B hardening phase and the Ni₃Fe matrix. It is also shown that the hardening phases form plate-shaped grains with thicknesses of 1–4 μm and more than 100 μm long, distributed in the form of colonies throughout the entire volume of the coating zone. In the direction to the transition zone, the shape of the structural components changes to circular with the diameter of up to 5 μm.     

NICE—An explicit numerical scheme for efficient integration of nonlinear constitutive equations

The paper presents a simple but efficient new numerical scheme for the integration of nonlinear constitutive equations. Although it can be used for the integration of a system of algebraic and differential equations in general, the scheme is primarily developed for use with the direct solution methods for solving boundary value problems, e.g. explicit dynamic analysis in ABAQUS/Explicit. In the developed explicit scheme, where no iteration is required, the implementation simplicity of the forward-Euler scheme and the accuracy of the backward-Euler scheme are successfully combined. The properties of the proposed NICE scheme, which was also implemented into ABAQUS/Explicit via User Material Subroutine (VUMAT) interface platform, are compared with the properties of the classical forward-Euler scheme and backward-Euler scheme. For this purpose two highly nonlinear examples, with the von Mises and GTN material model considered, have been studied. The accuracy of the new scheme is demonstrated to be at least of the same level as experienced by the backward-Euler scheme, if we compare them on the condition of the same CPU time consumption. Besides, the simplicity of the NICE scheme, which is due to implementation similarity with the classical forward-Euler scheme, is its great Advantage.     

Wave interactions and wave-structure scattering in nonlinear patterned waveguides

The nonlinear interactions between discrete optical solitons that propagate in different regimes of diffraction, and the nonlinear scattering of dispersive waves by local optical potentials, were studied experimentally. It is well known in electromagnetism that when linear coherent waves meet they interfere without interactions. Linear waves also scatter through local optical structures without exchanging any power with guided and anti-guided modes of these structures. When a focusing Kerr nonlinearity is present, linearly inhibited phenomena, which break these rules, are shown to exist. Our studies were performed with Silica glass and semiconductor AlGaAs nonlinear planar modulated waveguides, excited by ultra-short pulses in the near infrared spectral regime.     

Expression of urokinase plasminogen activator receptor in resting and activated bovine neutrophils

Changes in urokinase-plasminogen activator (u-PA) and u-PA receptor (u-PAR) expression at the protein and mRNA level in resting neutrophils and in neutrophils activated by phorbol myristate acetate (PMA) were examined. Low amounts of u-PA were found intracellularly or membrane-bound in resting neutrophils. However, incubation of resting neutrophils with purified exogenous u-PA (10 IU/ml) revealed extensive binding of u-PA to cell membranes. Excess amino-terminal fragment of the u-PA molecule, a proteolytically inactive fragment of u-PA (amino acids 1-135) blocked binding of exogenous u-PA to the cell membrane. These results, collectively, indicate that the binding of u-PA is specific and that resting neutrophils have unoccupied u-PA receptors on their cell membrane. Addition of PMA led to an increase (P < 0.01) in total cell-associated, membrane-bound u-PA activity and u-PA mRNA expression by bovine neutrophils. In contrast. PMA increased u-PAR mRNA levels but this was accompanied by a decrease (2.5-fold; P < 0.01) in free, unoccupied u-PA binding sites. No significant effects on total cell-associated or membrane-bound u-PA were found when neutrophils were treated with 4-phorbol 12,13 didecanoate, a phorbol ester that does not activate protein kinase C (PKC). Furthermore, addition of 1-(5-isoquinolinesylphonyl)-2-methlylpiperazine dihydrochloride (H-7), a potent PKC inhibitor, blocked the effect of PMA on total cell-associated u-PA activity. Thus, PKC plays a role in the modulation of u-PA and u-PAR by PMA in bovine neutrophils.     

A feasibility study for electrical impedance tomography as a means to monitor tissue electroporation for molecular medicine

Molecular medicine involves the introduction of macromolecules, such as drugs or gene constructs, into specific cells of the body. Electroporation, which uses electric pulses to permeate cell membranes, is a method for achieving this. However, as with other molecular medicine procedures, it lacks a real-time mechanism to detect and control which cells have been affected. We propose and demonstrate, via computer simulation, that electrical impedance tomography has the potential for detecting and imaging electroporation of cells in tissue in real-time, thereby providing feedback for controlling electroporation.