Application of satellite radar data suggest that the Kharga Depression in south-western Egypt is a fracture rock aquifer

SIR-C and Radarsat radar data have been used to map structural and fluvial features in south-western Egypt in order to identify new ground-water resources in fracture rock aquifer settings. These radar data show broad areas of the desert are dissected by a dense fluvial network of palaeochannels. Radar data are ideal for mapping palaeochannels since some are sand covered (L- band has the ability to penetrate to at least 2 m beneath the sand in arid areas) and many show pronounced structural control (radar clearly depicts the scarp faces of faults). Strong structural control of drainage is consistent with the development of fracture rock aquifers. Five types of channel morphologies have been identified. These are: channels with a stepwise pattern; braided channels; dendritic and trellis-like channels with pronounced structural control; and flood features that follow regionally extensive faults (up to 50 km length). The regionally extensive faults drain numerous wadis and extend for tens of kilometres in length, and likely reflect the existence of several connecting horizontal aquifers in the subsurface. These regional faults converge on the Kharga Depression, indicating a principal megawatershed in south-western Egypt leads to the subsurface here. The other fault types are more local in extent, thus reflect fracture rock aquifers of more limited areal extent.     

Evaluation of polycaprolactone − poly‐D,L‐lactide copolymer as biomaterial for breast tissue engineering

The potential of the copolymer polycaprolactone‐co‐ poly‐d ,l ‐lactic acid (PCLLA ) as a biomaterial for scaffold‐based therapy for breast tissue engineering applications was assessed. First, the synthesized PCLLA was evaluated for its processability by means of additive manufacturing (AM ). We found that the synthesized PCLLA could be fabricated into scaffolds with an overall gross morphology and porosity similar to that of polycaprolactone. The PCLLA scaffolds possessed a compressive Young's modulus (ca 46 kPa ) similar to that of native breast (0.5 ? 25 kPa ), but lacked thermal stability and underwent thermal degradation during the fabrication process. The PCLLA scaffolds underwent rapid degradation in vitro which was characterized by loss of the scaffolds' mechanical integrity and a drastic decrease in mass‐average molar mass (M _w) and number‐average molar mass (M _n) after 4 weeks of immersion in phosphate buffer solution maintained at 37 °C. The tin‐catalysed PCLLA scaffold was also found to have cytotoxic effects on cells. Although the initial mechanical properties of the PCLLA scaffolds generally showed potential for applications in breast tissue regeneration, the thermal stability of the copolymer for AM processes, biocompatibility towards cells and degradation rate is not satisfactory at this stage. Therefore, we conclude that research efforts should be geared towards fine‐tuning the copolymer synthesizing methods. © 2016 Society of Chemical Industry     

Erfahrungen bei der Bestimmung der Bindungsverhältnisse des Stickstoffs in Stählen durch Heißextraktion mit Wasserstoff

Untersuchung über die Nitridausscheidung in Stählen durch Bestimmung eines Stickstoffanteils, der durch Heißextraktion mit Wasserstoff ermittelt wird (N_H). Ergebnisse eines Ringversuches. Beschreibung des Verfahrens und Beurteilung von Fehlermöglichkeiten. Anwendungen.     

Dynamic force microscopy imaging of native membranes

We employed magnetic ACmode atomic force microscopy (MACmode AFM) as a novel dynamic force microscopy method to image surfaces of biological membranes in their native environments. The lateral resolution achieved under optimized imaging conditions was in the nanometer range, even when the sample was only weakly attached to the support. Purple membranes (PM) from Halobacterium salinarum were used as a test standard for topographical imaging. The hexagonal arrangement of the bacteriorhodopsin trimers on the cytoplasmic side of PM was resolved with 1.5nm lateral accuracy, a resolution similar to images obtained in contact and tapping-mode AFM. Human rhinovirus 2 (HRV2) particles were attached to mica surfaces via nonspecific interactions. The capsid structure and 2nm sized protein loops of HRV2 were routinely obtained without any displacement of the virus. Globular and filamentous structures on living and fixed endothelial cells were observed with a resolution of 5-20nm. These examples show that MACmode AFM is a favorable method in studying the topography of soft and weakly attached biological samples with high resolution under physiological conditions.     

Hydrodynamic damping of a magnetically oscillated cantilever close to a surface

We studied the frequency response of a magnetically driven atomic force microscope (AFM) cantilever close to a sample surface in liquids. Amplitude–frequency (tuning) curves showed pronounced differences in dependence on the tip–sample separation (from 1 to 50 μm), with significant shifts of the resonance peak. A model was developed in which the cantilever was described in a full shape manner and the hydrodynamic forces acting on the cantilever were approximately calculated. The slight inclination of the cantilever to the surface (15°) leads to a force profile along the cantilever. Therefore, the mathematical problem can be strictly solved only numerically. For an approximate analytical solution, the hydrodynamic force profile was approximated by a constant force along the cantilever for large separations and by a point force acting on the tip of the cantilever for small separations. The theoretical results calculated within this model agreed well with the experimental data and allowed to determine the cantilever mass in liquid M^*, the joint mass at the tip end m_t^*, and the coefficient of viscous interaction of the cantilever with free liquid, γ_∞.