Effect of Ionic Strength on the Thermal Stability of DNA Origami Nanostructures

The stability of DNA origami nanostructures in aqueous media is closely tied to the presence of cations that screen electrostatic inter-helix repulsion. Here, the thermal melting behavior of different DNA origami nanostructures is investigated in dependence on Mg²⁺ concentration and compared to calculated ensemble melting temperatures of the staple strands used in DNA origami folding. Strong deviations of the measured DNA origami melting temperatures from the calculated ones are observed, in particular at high ionic strength where the melting temperature saturates and becomes independent of ionic strength. The degree of deviation between the measured and calculated melting temperatures further depends on the superstructure and in particular the mechanical properties of the DNA origami nanostructures. This indicates that thermal stability of a given DNA origami design at high ionic strength is governed predominantly not by electrostatic inter-helix repulsion but mostly by mechanical strain.     

Ortsaufgelöste Stromdichtemessung in PEM‐Elektrolyse‐Zellen

The present analysis shows the local distribution of current density and EIS measurements along the channel coordinate of a single‐channel proton‐exchange membrane water electrolysis cell. Measurements for operating modes with one sufficiently high and one insufficiently low stoichiometric water ratio were carried out, in order to observe effects on the current density distribution. Furthermore, global and local EIS measurements were performed to distinguish between the voltage loss differences in the two cases. The local analysis has shown that the level of membrane and catalyst hydration under low stoichiometric conditions can be distributed highly inhomogeneous in the longitudinal direction, with the most pronounced dehydration towards the end of the channel.     

Microstructural features of dynamic recrystallization in alloy 625 friction surfacing coatings

In friction surfacing (FS), material is deposited onto a substrate in the plasticized state, using frictional heat and shear stresses. The coating material remains in the solid state and undergoes severe plastic deformation (SPD) at high process temperatures (≈0.8 T_melt), followed by high cooling rates in the range of 30?K/s. Dynamic recrystallization and the thermal cycle determine the resulting microstructure. In this study, Ni-based alloy 625 was deposited onto 42CrMo4 substrate, suitable, for instance, for repair welding of corrosion protection layers. Alloy 625 is known to undergo discontinuous dynamic recrystallization under SPD, and the resulting grain size depends on the strain rate. The coating microstructure was studied by microscopy and electron backscatter diffraction (EBSD). The coatings exhibit a fully recrystallized microstructure with equiaxed grains (0.5–12?µm) and a low degree of grain average misorientation. Flow lines caused by a localized decrease in grain size and linear alignment of grain boundaries are visible. Grain nucleation and growth were found to be strongly affected by localized shear and nonuniform material flow, resulting in varying amounts of residual strain, twins and low-angle grain boundaries in different regions within a single coating layer’s cross section.

FS can be used to study dynamic recrystallization at high temperatures, strains and strain rates, while at the same time materials with a recrystallization grain size sensitive to the strain rate can be used to study the material flow during the process.     

Possibilities and limitations of preparing silica/collagen/hydroxyapatite composite xerogels as load-bearing biomaterials

The combination of silica and collagen was identified in natural composites and recently recognized to be a valuable system for the preparation of innovative biomaterials for bone substitution applications. The present study reports on the development of silica/collagen composites, investigation of the underlying formation processes as well as further interactions with hydroxyapatite as a third phase. The possibilities and limitations of the material concept based on the sol-gel strategy were screened and characteristic composition ranges were identified. The gelation determining the processing time is strongly linked to the pH of silicic acid and collagen suspension mixtures as well as the buffer used and collagen concentration. The templating activity of collagen for silica formation is driven by primary amine groups as suggested by biochemical analysis and scanning electron microscopy. A high solid concentration in the initial hydrogels is essential in order to maintain the sample shape during transformation into monolithic and compact xerogels. The presence of fibrillar collagen significantly enhances the compressive strength of the xerogels up to 200 MPa and strain to fracture of up to 11%. The modular concept of the composite xerogel formation process allows incorporation of further phases such as calcium phosphate phases or prospectively drugs for the treatment of local or systemic diseases, opening large perspectives for the development of multifunctional bone implants.     

Laparoscopic resection of a mesenteric cyst]

The authors report a case of an unusual abdominal tumor-mesenteric cyst. When it is found active surgical approach is recommended. Laparoscopic resection of the cyst is considered as the method of choice.     

Parallel optical interconnection for uncoded data transmission with1 Gb/s-per-channel capacity, high dynamic range, and low powerconsumption

The design, realization, and characterization of a multichannel dc-coupled ECL-voltage compatible parallel optical interconnection with a bit rate of up to 1 Gb/s-per-channel is reported. The transmitter module consists of an array of laser diodes with low threshold currents and the 50 Ω matching network, the receiver module of a photo diode array and an amplifier array. All the opto-electronic and electronic components are fabricated as arrays with a pitch of 250 μm. The total power consumption is 110 mW per channel, For a BER <10¹⁴ the dynamic range is 15 dB for a bit rate per channel of 200 Mb/s, 13 dB for 630 Mb/s, and 8 dB for 1 Gb/s. The channel crosstalk is below -48 dB (electrical). The size of the opto-electronic parts (12 channels, without electrical connectors) is only 10 mm (length)×5 mm (width)×4 mm (height)     

Ion channel are sensitive to gravity changes

The effects of gravity on alamethicin doped planar lipid bilayers and on reconstituted porins of Escherichia coli outer membrane, respectively, have been investigated in this paper. The aim of the study was to find out whether and how gravity influences the highly simplified system: membrane-ion channel, in order to provide a novel approach to the explanation of gravity effects on living systems. This is necessary, as even single cells can react to gravity changes without having perceptive organelles. The mechanism of this detection is not clear yet. One possibility might be the detection of gravity by the membrane itself, or by the interaction of integral membrane proteins with gravity. Here we show for the first time that gravity directly influences the integral open state probability of native ion channels (porins) incorporated into planar lipid bilayers. Under hypergravity, especially the open state probability of porins is increased, whereas it is decreased in the microgravity case. The dependency is sigmoidal with the steepest region at 1 to 1.3 g. In the light of these experiments, a general effect of gravity on ion channels and membranes seems to be reasonable, possibly providing an explanation for several impacts of gravity on living systems.