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Adopting a systems approach, parental cancer has its impact on patients, spouses, and dependent children. The purpose of the current study was to examine family functioning dependent on parental disease [...]

Atomic force microscopy (AFM) was used to determine the mechanical properties as the indentation modulus of native and crosslinked poly(l-lysine) (PLL)/hyaluronic acid (HA) multilayer films by static force measurements. The influence of the surrounding medium on the mechanical properties of the films after preparation is investigated. The indentation modulus of native and crosslinked film was measured at different pH values, ionic strengths and temperatures. The native HA/PLL films, which behave like a physical gel, show the highest values of the indentation modulus for an intermediate pH value and low ionic strength. Any changes in the pH or an increase in the ionic strength/temperature decreases the measured indentation modulus. In contrast, the crosslinked films show an increase by a factor of 80 in the indentation modulus but no response to changes in the pH, ionic strength or temperature; they behave like a chemical gel. The pH, ionic strength and temperature used in this work are close to the in vivo conditions and thus give a fundamental point of view on the nanomechanical response of the PLL/HA films. Furthermore, information about the mechanical properties can be used for the understanding and manipulation of cell adhesion. [ABSTRACT FROM AUTHOR]

The article focuses on professor Gerhard Findenegg who was honored with a colloquium on his 75th birthday and mentions that colloquium was organized by the international graduate school (IRTG) which agreed to contribute for the periodical.

Using a recently developed crystal growth technique (see Fig. 1), we have succeeded in creating a two-dimensional (2D) electron system that is bent at an atomically sharp angle of 90°1. Naming the two 2D systems after their substrate (S) and precleave (P) facets, we can measure their densities ns and np. In the presence of a tilted magnetic field, this system realizes an abrupt junction between two quantum Hall effect (QH) systems with arbitrary filling factors2νs = nsh/eBcos(θ) and νp = nph/eBsin(θ). When the two filling factors are equal νs = νp, the corner junction represents a multimode wire with the maximum number of forward & reverse moving modes equalling the filling factor ν plus two spin degenerate modes from corner-accumulation wire. The conductance of this bent QH system dI/dV(V) or G(T) can be characterized with four-point measurements. As long as the excitation energy (V or T, respectively) is smaller than the QH gap energy, there is no scattering of electrons away from the wire system to the 2D bulk and the transport is truly one-dimensional. The devices studied here are from 0.4 - 4 mm long with ohmic contacts alloyed on both facets away from the junction. The resulting 1D wire at the corner junction has exhibited metallic, insulating, and critical phases depending on filling factor, with all 1D conductances of order 0.02e2/h or below. The insulating 1D behavior occurs for ν = 1 and ν = 2, and is manifest in a vanishing 1D conductance at low temperatures and low dc voltage biases. Metallic 1D behavior occurs for ν = 1/3 where the conductance rises with decreasing temperature and the dc bias shows a large zero-bias peak in the differential conductivity. The so-called critical behavior has only weak temperature dependence and a weak zero-bias dip in the dc bias voltage dependence. The conductance G at ν = 3 and ν = 4 goes inversely with the wire length L indicating that scattering is distributed equally along the wire length. These observations can be partly explained with Hartree calculations of the bent quantum Hall junction. Low magnetic fields (ν = 3 and 4) are expected to manifest a multimode wire, which provides a basis for understanding the critical phase. Higher magnetic fields (ν = 1 and 2) are expected to open up a gap in the 1D energy spectrum at the corner, resulting in the experimentally observed insulating phase. Alternatively, disorder may also explain the 1D insulating behavior via scaling theory of localization. The highest magnetic fields for the fractional state ν = 1/3 show the remarkable metallic phase which might be explained in terms of an antiwire between counterpropagating ν = 1/3 Luttinger liquid edges which are randomly coupled by electron back-scattering events3. [ABSTRACT FROM AUTHOR]

A technique for the fabrication of single-electron transistors (SETs) on tips for use in scanning probe microscopy is presented. The tips are micromachined out of an MBE-grown AlGaAs-GaAs heterostructure with a trench within each tip. The SETs are produced by aluminum evaporation and oxidation, and natural shadowing by the trench is used to separate the source and drain electrodes. By separating adjacent tips also by trenches, the concept allows the fabrication of tip arrays for parallel probing. [ABSTRACT FROM AUTHOR]

We fabricated laterally confined GaAs–AlGaAs superlattices with diameters between 500 nm and 2 μm. With decreasing device diameter, a gap evolves in the current–voltage curve around zero bias and steps show up at the onset of the current. This behavior is interpreted in terms of Coulomb blockade, a depletion of the center of the superlattice, and single-electron tunneling through donor levels. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Scanning force microscope measurements of the Hall potential distribution of a two-dimensional electron system (2DES) in the quantum Hall regime reveal the presence of a partial depletion along the border between the 2DES and the good ohmic metal contact: incompressible strips are formed in high magnetic fields along this border, decoupling the bulk region of the 2DES from the contact. This finding clarifies the role of potential probe contacts in Hall bar devices and might affect the interpretation of conductance measurements on Corbino devices. [Copyright &y& Elsevier]