Search results for "engineering.material"
showing 10 items of 2352 documents
Counter-propagating difference frequency mixing in diamond with terahertz waves
2013
We investigate four-wave mixing between terahertz and optical pulses in diamond. We observe the occurrence of sum and difference frequency generation, with the latter being phase-matched for terahertz pulses counter-propagating to the optical field.
Explicit cloud-top entrainment parameterization in the global climate model ECHAM5-HAM
2011
New developments in the turbulence parameterization in the general circulation model ECHAM5-HAM are presented. They consist mainly of an explicit entrainment closure at the top of stratocumulus-capped boundary layers and the addition of an explicit contribution of the radiative divergence in the buoyancy production term. The impact of the new implementations on a single column model study and on the global scale is presented here. The parameterization has a "smoothing" effect: the abnormally high values of turbulence kinetic energy are reduced, both in the single column and in the Californian stratocumulus region. A sensitivity study with prescribed droplet concentration shows a reduction i…
Magnetic Control of Convection in Liquid Metal Heated from Above
1999
We investigated experimentally the buoyancy driven convection induced by localized central heating from above in cylindrical tanks filled with liquid metal eutectic alloy (low-Prandtl-number liquid). The experiments were carried out for two aspect ratios A = (radius/height) = 4.125 and 0.333. Time-averaged local temperature distributions and radial and azimuthal velocity components in the liquid at different distances from heater axis were measured. It is shown that maximum temperature gradient is centered in vicinity heater. Temperature difference in radial direction creates pressure gradient between heater and cold wall regions. This gradient leads to upraising of liquid nearly heater and…
Impact of Green Manure and Vermicompost on Soil Suppressiveness, Soil Microbial Populations, and Plant Growth in Conditions of Organic Agriculture of…
2015
The impact of organic amendments on the soil microorganisms and plant growth and health in conditions of organic agriculture of Northern temperate climate was analyzed. Some case studies dealing with green manure or vermicompost amendments are discussed giving deeper analyses of the vermicompost impact on plant growth. The first case study is about the impact of green manure on soil microbial populations and soil suppressiveness against such pathogens as late blight, potato scab, and black scurf of potato in organic agriculture. The second case study is about the use of vermicompost in organic starch potato cultivation. Significantly higher numbers of all groups of analyzed cultivable micro…
Effect of spatial distribution of impurity ions on the signal of ‘C/O monitor for Wendelstein 7-X’ - an indicator of plasma wall interactions
2022
The ‘C/O monitor’ is a dedicated diagnostic system designed to monitor light impurities (B, C, N and O) in the Wendelstein 7-X (W7-X) stellarator. Its main goal is to provide fast (∼1 ms) information about the impurity level which is measured from a large plasma volume (high throughput). Its first subsystem dedicated to measure Lyman-α lines of H-like carbon (C5+ − 3.4 nm – used as PFC material) and oxygen (O7+ − 1.9 nm – common impurity absorbed by inner vessels’ walls) is going to be commissioned during the next Operational Phase of W7-X. Since the radiated photon intensity of a given impurity depends strongly on plasma kinetic parameters (Te, ne) and impurity transport, it is important t…
Stabilization of polar solid oxide surfaces: competition between adsorption and reconstruction
2002
Multi-cationic spinel compounds are solids that exhibit polar faces. X-ray Photoelectron spectroscopy revealed the main phenomena allowing the stabilization of these faces, carried out as a function of the material treatment, particularly the cooling rate after thermal treatment at a high temperature (1200°C). This study showed that, whatever the cooling rate, each sample is subject to a significant hydroxylation that reduces the polarity. Nevertheless, it appears that the hydroxyl group content at the surface is a strong function of the cooling rate. Indeed, whereas quenched materials are subject to high levels of hydroxylation, slowly cooled samples are sparingly hydroxylated. This phenom…
Potential Off-Flavour Compounds from Chloro-Bleaching of Pulp and Chlorodisinfection of Water
1983
Chlorobleaching of pulp is the most important source of organochlorine pollutants in the Finnish aquatic ecosystems. Similar types of pollutants are formed during chlorodisinfection of water. The model compound approach employed in our laboratory has revealed the structures and amounts of pollutants formed and has made the interpretation and assay of individual organochlorine compounds in the environment possible. Tainting of fish near chlorination plants is frequently observed. Especially chlorinated phenols and anisoles (microbial metabolites of the former) are chlorination products which are known to have a strong odour and taste at very low concentrations. Other chlorinated products, wh…
Salt accumulation and effects within foliage of Tilia × vulgaris trees from the street greenery of Riga, Latvia
2020
International audience; Green infrastructures within sprawling cities provide essential ecosystem services, increasingly undermined by environmental stress. The main objective in this study was to relate the allocation patterns of NaCl contaminants to injury within foliage of lime trees mechanistically and distinguish between the effects of salt and other environmental stressors. Using field material representative of salt contamination levels in the street greenery of Riga, Latvia, the contribution of salt contaminants to structural and ultrastructural injury was analyzed, combining different microscopy techniques. On severely salt-polluted and dystrophic soils, the foliage of street lime …
Toxicity and mutagenicity of waste waters from Baikalsk Pulp and Paper Mill: Evaluation of pollutant contamination in Lake Baikal
1998
Lake Baikal has no agricultural and only little municipal pollution. Instead a potential source of pollution is the Baikalsk Pulp and Paper Mill (BPPM). All waste waters of the mill are mechanically, biologically and chemically purified and there are sedimentation and aeration ponds at the final stage. In this study the efficiency of the waste water purification was detected by testing toxicity and mutagenicity. Waters and sediments were collected along the cellulose bleaching process and waste water treatment. Free and bound polychlorinated phenols, guaiacols, catechols, anisoles and veratroles were analysed. Cytotoxicity of diethylether-extracted waste waters was screened by measuring tot…
Chlorocymenes, cymenenes and other chlorohydrocarbons in pulp mill effluents, sludges and exposed biota
1992
Abstract Polychlorinated cymenes (PCYMS) and cymenenes (PCYMD) were analyzed by GC/LRMS/SIM in effluents and sludges of three different pulp mills and in fish and mussels exposed to pulp mill effluents. The levels of PCYMS+PCYMD were 0.3–4.8 μg/l in total effluents,