Polyethylene and cobalt–chromium molybdenium particles elicit a different immune response in vitro

Periprosthetic osteolysis is a major clinical problem that limits the long-term survival of total joint arthroplasties. Particles of prosthetic material stimulate immune competent cells to release cytokines, which may cause bone loss and loosening of the prosthesis. This study examined the following hypothesis. Polyethylene and titanium particles elicit a different immune response in vitro. To test these hypotheses, we used the human bone marrow cell culture model that we have established and previously used to examine particle associated cytokine release. Ultra high molecular weight polyethylene (UHMW-PE) induced a proliferation of CD14 positive cells (monocytes/macrophages) whereas cobalt chromium molybdenium (CoCrMb) particles demonstrated an increased proliferation of CD66b positive cells (granulocytes). Light and scanning microscopic evaluation revealed that the UHMW-PE particles, which have built large clusters of particles (Ø7, 5 μm), were mainly surrounded by the cells and less phagocytosed. On the other hand the smaller particles from CoCrMb have been phagocytosed by the cells. These results provide strong support for our hypothesis: that wear particles derived from prosthetic materials of different material can elicit significantly different biologic responses. In summary the results suggest that the “in vitro” response to wear particles of different biomaterials should be investigated by culture systems of various lineages of cells.     

Water-soluble organo-silica hybrid nanowires

There has been growing interest in the past decade in one-dimensional (1D) nanostructures, such as nanowires, nanotubes or nanorods, owing to their size-dependent optical and electronic properties and their potential application as building blocks, interconnects and functional components for assembling nanodevices. Significant progress has been made; however, the strict control of the distinctive geometry at extremely small size for 1D structures remains a great challenge in this field. The anisotropic nature of cylindrical polymer brushes has been applied to template 1D nanostructured materials, such as metal, semiconductor or magnetic nanowires. Here, by constructing the cylindrical polymer brushes themselves with a precursor-containing monomer, we successfully synthesized hybrid nanowires with a silsesquioxane core and a shell made up from oligo(ethylene glycol) methacrylate units, which are soluble in water and many organic solvents. The length and diameter of these rigid wires are tunable by the degrees of polymerization of both the backbone and the side chain. They show lyotropic liquid-crystalline behaviour and can be pyrolysed to silica nanowires. This approach provides a route to the controlled fabrication of inorganic or hybrid silica nanostructures by living polymerization techniques.     

From Al2O3-supported Ni(II)-ethylenediamine Complexes to CO Hydrogenation Catalysts: Importance of the Hydrogen Post-treatment Evidenced by XPS

Ni (7 wt%)/Al₂O₃ catalysts prepared by decomposition of Ni(II)-ethylenediamine complexes in inert atmosphere initially contain a mixture of metallic and oxidized nickel. X-ray photoelectron spectroscopy shows that after a hydrogen treatment at 500 °C, the system contains more metallic nickel than catalysts prepared from the usual precursor, nickel nitrate. Carbonaceous species resulting from the partial oxidation of ethylenediamine are also eliminated. The catalyst post-treated in hydrogen exhibits a high metallic surface area accessible to reactants and is able to catalyze CO methanation.     

Assessing the impact of changes in landuse and management practices on the diffuse pollution and retention of nitrate in a riparian floodplain

In many European lowland rivers and riparian floodplains diffuse nutrient pollution is causing a major risk for the surface waters and groundwater to not achieve a good status as demanded by the European Water Framework Directive. In order to delimit the impact of diffuse nutrient pollution substantial and often controversial changes in landuse and management are under discussion. In this study we investigate the impact of two complex scenarios considering changes in landuse and land management practices on the nitrate loads of a typical lowland stream and the riparian groundwater in the North German Plains. Therefore the impacts of both scenarios on the nitrate dynamics, the attenuation efficiency and the nitrate exchange between groundwater and surface water were investigated for a 998.1 km(2) riparian floodplain of the Lower and Central Havel River and compared with the current conditions. Both scenarios target a substantial improvement of the ecological conditions and the water quality in the research area but promote different typical riparian landscape functions and consider a different grade of economical and legal feasibility of the proposed measures. Scenario 1 focuses on the optimisation of conservation measures for all natural resources of the riparian floodplain, scenario 2 considers measures in order to restore a good status of the water bodies mainly. The IWAN model was setup for the simulation of water balance and nitrate dynamics of the floodplain for a perennial simulation period of the current landuse and management conditions and of the scenario assumptions. The proposed landuse and management changes result in reduced rates of nitrate leaching from the root zone into the riparian groundwater (85% for scenario 1, 43% for scenario 2). The net contributions of nitrate from the floodplain can be reduced substantially for both scenarios. In case of scenario 2 a decrease by 70% can be obtained. For scenario 1 the nitrate exfiltration rates to the river drop even below the infiltration rates from the river, the riparian floodplain in that scenario represents a net sink for river derived nitrate. As the nitrate contributions from the investigated riparian floodplain represent only a small proportion of the total nitrate loads within the river (1% p.a.) the overall impact of the scenario measures on the nitrate loads at the river outlet remains small. However, during the ecologically most sensitive summer periods under current conditions nitrate contributions from the riparian groundwater of the Lower and Central Havel River (which covers only 5% of the area of the Havel catchment) represent more than 20% of the river loads. By the implementation of the investigated landuse changes within the research area the groundwater derived nitrate contributions could be halved to only 10% during summer baseflow conditions.     

Compact cw Terahertz Spectrometer Pumped at 1.5 μm Wavelength

A compact and low-cost continuous wave terahertz spectrometer operating at an optical wavelength of 1.5 μm is presented. The spectrometer employs high power distributed feedback (DFB) laser diodes in integrated “butterfly” packages. No further optical amplification of the beating signal is required. An integrated photodiode antenna with an output power of 5 μW at 500 GHz is used as efficient terahertz emitter. Employing low-temperature grown (LT-) InGaAs/InAlAs photoconductive receivers as coherent detectors, SNR values of the terahertz power up to 75 dB are attained at an integration time of 300 ms. Accurate characterization of the thermal tuning behavior of the DFBs and precise thermal control yield an absolute accuracy of 1 GHz and a resolution of better than 5 MHz, without any on-line monitoring of the optical frequency. Due to the high frequency resolution no delay line is needed to vary the terahertz phase.     

The new Chancellory

This paper originally accompanied the presentation of the project for the new Chancellory.     

A Two-Dimensional Electron Gas as a Sensitive Detector for Time-Resolved Tunneling Measurements on Self-Assembled Quantum Dots

A two-dimensional electron gas (2DEG) situated nearby a single layer of self-assembled quantum dots (QDs) in an inverted high electron mobility transistor (HEMT) structure is used as a detector for time-resolved tunneling measurements. We demonstrate a strong influence of charged QDs on the conductance of the 2DEG which allows us to probe the tunneling dynamics between the 2DEG and the QDs time resolved. Measurements of hysteresis curves with different sweep times and real-time conductance measurements in combination with an boxcar-like evaluation method enables us to unambiguously identify the transients as tunneling events between the s- and p-electron QD states and the 2DEG and rule out defect-related transients.     

Towards Autonomous Micro UAV Swarms

Micro Unmanned Aerial Vehicles (UAVs) such as quadrocopters have gained great popularity over the last years, both as a research platform and in various application fields. However, some complex application scenarios call for the formation of swarms consisting of multiple drones. In this paper a platform for the creation of such swarms is presented. It is based on commercially available quadrocopters enhanced with on-board processing and communication units enabling full autonomy of individual drones. Furthermore, a generic ground control station is presented that serves as integration platform. It allows the seamless coordination of different kinds of sensor platforms.     

Serum Phospholipid Transfer Protein Activity After a High Fat Meal in Patients with Insulin-Treated Type 2 Diabetes

Plasma phospholipid transfer protein (PLTP) mediates both net transfer and exchange of phospholipids between different lipoproteins. Animal studies have shown that it is closely related to the development of atherosclerosis. Although many studies have indicated that PLTP activity is increased in diabetes mellitus, the role of PLTP in diabetes is still unclear. To evaluate the influence of a high-fat meal on PLTP activity, 50 nondiabetic patients with coronary heart disease (CHD), 50 insulin-treated Type 2 diabetics, and 50 healthy controls were included. We determined PLTP activity before and 4 and 8 h after a high-fat meal. As expected, serum PLTP activity was significantly higher in CHD patients than in healthy controls (71.0 ± 46.2 vs. 54.0 ± 33.8 pmol/μl/h, P = 0.032) at baseline. More importantly, we found that serum PLTP activity increased to its maximum 4 h after fat loading and then decreased to nearly basal levels after 8 h both in controls and CHD patients. In contrast, PLTP activity continuously increased during this time period in the diabetic patients. With regards to the data from this study we hypothesize that serum PLTP is involved in the clearance of postprandial lipoproteins and this process is attenuated in diabetes. Since postprandial lipoproteins are atherogenic, the delay in clearance of these particles could play an important role in the development of atherosclerosis in patients with diabetes mellitus.