System Analysis of a DoD Print Head for Direct Writing of Conductive Circuits

The inkjet-printing principle is becoming more and more important for new applications besides conventional graphic printing. The target at our institute is to print conductive silver lines and areas of different widths and thicknesses. Based on a drop-on-demand (DoD) micro feeding system, a colloidal ink printer was developed to print conductive circuits. The printer has a stationary piezo-driven print head with a nozzle diameter of 100 μm. With such a nozzle, conductive paths with a width between 110 and 250 μm can be realized. A waveform generator is used to actuate the print head's piezo actuator. The most common control signal is a nearly rectangular voltage pulse. Shape, duration, and amplitude of the piezo control signal influence the stability of the printing process and thus the quality of the printed electrical structures significantly. Different rise and dwell times or pulse shapes can be considered to optimize the printing process. In this article, the piezo control signal's shape is analyzed, varied and the print head's system behavior is characterized. In a performance and signal analysis, the influence of the piezo input signal's shape on the transient behavior of the piezo output energy signal is identified. An optimized piezo control signal shall be achieved. In conclusion, a method is presented to measure droplet parameters such as radius, speed, and volume.     

The impact of a sewage treatment plant's effluent on sediment quality in a small bay in Lake Geneva (Switzerland–France). Part 2: Temporal evolution of heavy metals

The Bay of Vidy is the most contaminated area of Lake Geneva, Switzerland, as a result of the release of treated and untreated waste water from the municipal sewage treatment plant of the city of Lausanne and its surroundings. The reconstruction of the historical deposition of heavy metals in the sediment of the bay has been performed by the analysis of several dated (radiocaesium) sediment cores. The presence of sewage‐derived contaminants in the Bay of Vidy since the beginning of the sewage treatment plant's operations in 1964 is clearly observed, when a sharp increase in heavy metal contents is recorded, with maximum concentrations of cadmium, copper, zinc and lead occurring between the late 1960s and early 1970s. Despite considerable improvement in recent times, the present concentrations of the investigated heavy metals in sediments of the Bay of Vidy are still higher than concentrations measured at the centre of the lake, the latter close to Lake Geneva's natural background values. It is concluded that the quantity of heavy metals deposited in the bay is considerable and, because of sediment instability, will constitute a potential hazard for biota.     

Gravitational drainage of compressible organic materials

A model was developed to simulate drainage of compressible particle suspensions, and study how cake compression and volumetric load influence the process. The input parameters were settling velocity, cake resistance and compressibility. These parameters were found using a new experimental method. Dextran‐MnO₂ particle suspensions were drained as these resemble organic waste slurries with respect to settling and compressibility. It was demonstrated that cake compressibility must be taken into account to obtain adequate simulations. This implies that pressurized filtration resistances cannot be used for drainage simulations. In the filtration step, a distinct increase of dry matter from top to bottom of the cake was observed. During the subsequent consolidation, the cake compressed and a uniform dry matter profile was found. The final dry matter content of the cake increased with feed concentration and volumetric load. The drainage time increased proportionally with feed concentration and, more importantly, proportionally with squared volumetric load. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Cold Chemical Lamination—New Bonding Technique of LTCC Green Tapes

The low-temperature co-fired ceramic (LTCC) technology enables fabrication of sensors, actuators, microfludic devices² and fuel cells. The structures consist of screen-printed components, gas/liquid channels, reactive chambers and mixers. The lamination process determines the quality of such devices. Thermo-compression is the most popular bonding method. The LTCC green tapes are joined together at high temperature (up to 80°C) and high pressure (up to 30 MPa) for 2 to 15 minutes. The method allows good encapsulation of the LTCC structures, but the channels geometry is strongly affected by elevated temperature and pressure. Cold Chemical Lamination (CCL) is a new LTCC green tapes bonding technique, which allows for fabrication of 3D modules. A solvent-based method is used in the CCL lamination instead of the thermo-compression process. A special liquid agent is screen-printed on the green tape in the CCL method. The liquid melts the tape surface. Then the tapes are stacked and compressed at room temperature by a printing roll. The influence of the CCL and the thermo-compression methods on the chamber's geometry quality as well as basic electrical properties of screen-printed resistors (sheet resistance R_φ standard deviation of sheet resistance σ_R, variability coefficient of sheet resistance V_R, and long-term stability) are analyzed and compared in this paper. The bonding quality is examined by a scanning electron microscope (SEM).     

Synthesis and Biological Testing of N‐Aminoimidazole‐Based p38α MAP Kinase Inhibitors

The p38 mitogen‐activated protein (MAP) kinase α plays a central role in the regulation of cellular responses such as differentiation, proliferation, apoptosis, and inflammation. Inhibition of p38 results in decreased synthesis of pro‐inflammatory cytokines. To date, diverse p38α inhibitors are in phase II clinical trials for numerous cytokine‐dependent diseases. 2‐Sulfanylimidazole derivatives offer advantages over the prototype inhibitor SB 203580, including fewer cytochrome P450 interactions and better kinetic properties. The aim of this study was to develop novel 1,2,4,5‐tetrasubstituted pyridinylimidazoles with acyl residues at the imidazole N1 position that can interact with the kinase's hydrophobic region II (HR II) or sugar pocket (SP) to improve both selectivity and activity. The substitution pattern was optimized by variation of the acyl moiety at the N1 position of the N‐aminoimidazole core. Acylation of the amino function was used for optimization and led to potent p38α MAPK inhibitors.     

Low-pressure,thermo-compressive lamination

Lamination of green ceramic tapes is one of the most important technological processes in multilayer ceramic technology. Lamination affects the quality of all 3D structures (e.g., channels, chambers, membranes, etc.). Novel chemical methods of lamination reduce the deformation of 3D structures. However, these methods are useless in the fabrication of thin membranes and structures with thick-film electronic components or electric vias. Therefore, thermo-compressive lamination is still the best solution for the lamination of green ceramic tapes. Low-pressure thermo-compressive lamination with an insert material is presented in this paper. The influence of pressure and Low Temperature Cofired Ceramics (LTCC) material on the compressibility and shrinkage of LTCC, as well as the influence of the insert material on deflection and distortion of the membranes are presented and discussed in this paper.     

APPLICATION OF CONCENTRATED SOLAR RADIATION TO HIGH TEMPERATURE DETOXIFICATION AND RECYCLING PROCESSES OF HAZARDOUS WASTES

In many cases, hazardous wastes are subject to thermal treatment at elevated temperatures. Some types of wastes do not have a sufficient calorific value to cover the heat demand of the high temperature process. For thermal treatment of e.g. filter residues, dusts, sulfuric acid, aluminium dross, foundry sand, or waste water, supplementary energy supply is needed. The specific energy demand ranges from 0.5 to 2.5 kWh/kg (2–10 MJ/kg). An important aim of process optimisation is the reduction of (fossil) energy consumption and exhaust gas flow. Concentrated solar energy promises advantages when applied to high energy consuming waste treatment processes with regard to substitute fossil or electric energy consumption, to reduce CO₂ emissions, and exhaust gas flow. In parallel to conceptional studies, a solar-heated rotary kiln mini-plant has been designed and constructed for tests in the DLR solar furnace. The tests will give indications of boundary conditions for solar thermal treatment or conversion of selected hazardous materials.     

Ionic Space‐Charge Depletion in Lithium Fluoride Thin Films on Sapphire (0001) Substrates

Lithium fluoride thin films with various thicknesses have been grown on c‐plane sapphire substrates by radio‐frequency sputtering. The thin films are granular with a preferential [111] orientation of the grains. Thickness‐dependent measurements allow the separation of bulk and interface conductions. The normalized conductance decreases linearly with decreasing LiF layer thickness with a negative extrapolated intercept. DC polarization, AC impedance spectroscopy and electromotive force measurement indicate depletion of lithium ion vacancies as majority charge carriers and hence a negative space‐charge potential. A generalized Mott–Schottky approach within the model of heterogeneous doping fully explains the entire boundary defect chemistry.     

Rezente Mängel der Leichenschau und ihre historischen Ursachen: Eine Analyse aus medizingeschichtlicher Sicht

In recent years, the enactment of uniform national regulations concerning postmortem examination has become a persistent demand. There is strong criticism of the reliability of coroner's inquest: The education of most of the coroners in forensic medicine is found to be insufficient, and many experts report that medical examiners partly are neglectful for the inquest. The classification of the manner of death is also said to be deficient, the rate of misdiagnosis being only little below 50 %. Thus much emphasis is put on demanding a reinforced training of doctors in the field of the external examination of corpses. But only few of those reports make allowance for the fact that that most of the present deficiencies have their origin in the 19th century. As a matter of fact, from the outset the practise of coroner's inquest gave rise to criticism. Thus the present article traces the historical roots of postmortem examination in Germany. Special emphasis is placed on a comparison between the infancies of coroner's inquest and the current state. Actual and historical imperfections in the system of postmortem examination and striking similarities are pointed out.      

Simulation of Flow and Mass Transport in a Meander Microchannel Subject to Electroosmotic Pumping

We have investigated the flow and mass transport within an electroosmotically pumped incompressible liquid through a meander microchannel system. We employ two-dimensional, time-dependent finite element simulations in conjunction with a matched asymptotic treatment of the electrical double layers. The electroosmotic pumping is realized for two idealized and two realistic electrical fields, while a pressure-driven flow is used for comparison. We focus on the aspects of the electroosmotic transport.

We find for most of the electroosmotically driven cases rather complex flow fields, involving recirculation regions. These recirculation regions in all cases increase dispersion. (i) The least dispersion is associated with a plug-type velocity profile, which is obtained for an idealized purely wall-tangential orientation of the electrical field. (ii, iii) We find that both the idealized horizontal electrical field and the real electrical field between two vertical plates give considerably higher dispersion than the pressure-driven flow. Vertical plate electrodes, therefore, do not allow for a electrical field, which minimizes dispersion. (iv) The arrangement of two point electrodes at the in and out sections likewise proves to be no optimal means to reduce dispersion beyond the pressure-driven flow. Thus, meander geometries of channels, in general, cause severe problems if electroosmotic pumping needs to be achieved in combination with minimized dispersion.