Design comparison of experimental storm water detention systems treating concentrated road runoff

The aim was to assess the treatment efficiencies of experimental storm water detention (extended storage) systems based on the Atlantis Water Management Limited detention cells receiving concentrated runoff that has been primarily treated by filtration with different inert aggregates. Randomly collected gully pot liquor was used in stead of road runoff. To test for a 'worst case scenario', the experimental system received higher volumes and pollutant concentrations in comparison to real detention systems under real (frequently longer but diluted) runoff events. Gravel (6 and 20 mm), sand (1.5 mm), Ecosoil (inert 2 mm aggregate provided by Atlantis Water Management Limited), block paving and turf were tested in terms of their influence on the water quality. Concentrations of five-day at 20 degrees C ATU biochemical oxygen demand (BOD) in contrast to suspended solids (SS) were frequently reduced to below international secondary wastewater treatment standards. The denitrification process was not completed. This resulted in higher outflow than inflow nitrate-nitrogen concentrations. An analysis of variance indicated that some systems were similar in terms of most of their treatment performance variables including BOD and SS. It follows that there is no advantage in using additional aggregates with high adsorption capacities in the primary treatment stage.     

Volltr?nkung modifizierten Holzes mit Wachs

Acetylated timber, thermally modified timber (TMT) and timber modified with dimethylol-dihydroxy-ethylenurea (DMDHEU) was impregnated with wax. Subsequently, the influence of hydrophobic wax deposits on the capillary water uptake and the strength properties of the pre- modified timber were investigated. The water uptake in longitudinal direction decreased to 0.03?kg?m^?2?h^?0.5 for acetylated timber and 0.13?kg?m^?2?h^?0.5 for TMT. In tangential direction it was reduced to 0.02?kg?m^?2?h^?0.5 (acetylated wood) and 0.05?kg?m^?2?h^?0.5 (TMT). Thus, water uptake of acetylated timber was lowered by a maximum of factor 28 in longitudinal and factor 9 in tangential direction. For TMT, water uptake was reduced by factor 12 in both directions. For both cases, the pre-modified material without wax treatment was measured as reference. The bending and impact bending strength of TMT increased by a maximum of up to 45% and 64%, respectively. The Brinell hardness perpendicular to the grain rose by up to 420%. Consequently, strength losses due to thermal modification were partly compensated by subsequent wax impregnation. The compression strength increased by up to 47% and the modulus of elasticity by up to 66% for acetylated timber. For the same material, the hardness perpendicular to the grain peaked at 109?N/mm². The longitudinal water uptake of timber modified with DMDHEU decreased by a maximum of 45% after impregnation with wax, whereas Brinell hardness perpendicular to the grain increased by 150%. Besides diminished water uptake, a reinforcement of wood structure degraded after preceding modification can be accomplished by wax treatment.     

Transformations of carbon adsorbates on graphene substrates under extreme heat

We describe new phenomena of structural reorganization of carbon adsorbates as revealed by in situ atomic-resolution transmission electron microscopy (TEM) performed on specimens at extreme temperatures. In our investigations, a graphene sheet serves as both a quasi-transparent substrate for TEM and as an in situ heater. The melting of gold nanoislands deposited on the substrate surface is used to evaluate the local temperature profile. At annealing temperatures around 1000 K, we observe the transformation of physisorbed hydrocarbon adsorbates into amorphous carbon monolayers and the initiation of crystallization. At temperatures exceeding 2000 K the transformation terminates in the formation of a completely polycrystalline graphene state. The resulting layers are bounded by free edges primarily in the armchair configuration.     

Growth of self-assembled InP quantum islands for red-light-emittinginjection lasers

In order to achieve laser emission in the visible part of the spectrum, we have investigated the growth of self-assembled InP quantum dots on GaInP by low-pressure metal-organic vapor phase epitaxy (MOVPE) using the Stranski-Krastanow growth mode. Unlike the well-established InAs-GaAs system, when InP is deposited on GaInP, typically, two types of coherently strained islands with different sizes are formed. A high density of small islands is favored when using growth conditions with a reduced surface diffusion, i.e., low temperatures, high growth rates, and substrates with high misorientation angles. After the deposition of 3.4 monolayers of InP at 580°C on GaAs-substrates with a surface angle of 15° to the next (111)B-plane, 2.10¹⁰ InP dots per square centimeter with an average height of 4 nm were assembled. The emission of these InP islands at 1.72 eV (4.2 K) shows an inhomogeneous broadening of 42 meV because of the size fluctuation of the quantum dots. At 90 K, lasing from self-assembled InP quantum islands was observed above a threshold current density of 288 A/cm². The detected laser line is located at 1.8 eV, about 80 meV higher than is the ground-state transition energy. We attribute this behavior to lasing from excited states in agreement with power-dependent photoluminescence experiments. For temperatures above 150 K, the threshold current density increases dramatically because of a thermally activated escape of carriers up to 4.9 k17/cm² at room temperature, where the characteristic temperature is 35 K. Injection lasers containing stacked InP quantum islands and AlGaInP barrier layers with a higher band offset may exhibit an improved temperature dependence     

ESD On-Wafer Characterization: Is TLP Still the Right Measurement Tool?

The electrical characterization of devices and circuits regarding their electrostatic discharge (ESD) robustness is done by using several measurement tools. Transmission line pulsing (TLP) and human body model (HBM) testing are the commonly used methods. In this paper, TLP and HBM on-wafer setups are presented regarding their electrical schematics, the type of data that is obtained, and the required calibration methodologies. By using three case studies, both test methods are compared by showing their advantages and disadvantages. It is demonstrated that pulsed measurement methods like TLP testing are not always a suitable tool to fully assess the ESD performance of devices or circuits.     

Dust-generation characteristics of hardwoods during sanding processes

A study of the factors that influence dust-generation during the sanding process of Malaysian hardwoods was undertaken. It was found that the amount of wood removed during the sanding process predetermined dust-generation, although the wood density and abrasive grit used also played a role. Consequently, low density wood species produced higher dust-concentration due to its relative ease of sanding, and vice-versa. The results of the study suggest that minimizing dust-generation during the hardwood sanding process could be achieved by ensuring minimal amount of wood removal as well as the use of the coarsest possible abrasive grit in the process.