838 research outputs found
Design Theory Manual For ARMORFORM® Erosion Protection Mats
No full text1.0 Determination Of Forces Generated By Moving Water 1 1.1 Forces Due To Flowing Water 1 1.2 Forces Due To Wave Action 8 2.0 Resisting Forces Provided By Erosion Proteetion 11 2.1 ARMORFORM Mat Characteristics 11 2.2 Resisting Forces On Channel Bottom 12 2.3 Resisting Force On Slopes 17 2.4 Additional Resisting Force Given By Anchors 18 3.0 Design Of ARMORFORM Mat Erosion Proteetion 20 3.1 Mats In Channels With Flowing Water 20 3.2 Proteetion Against Wave Action 22 3.3 Design Charts 28KWP-collectio
Supplemental Material - Author gender and text characteristics in contemporary Swedish fiction
No full textSupplemental Material for Author gender and text characteristics in contemporary Swedish fiction by Mats Dahllöf in Language and Literature</p
Supplemental Material - Author gender and text characteristics in contemporary Swedish fiction
No full textSupplemental Material for Author gender and text characteristics in contemporary Swedish fiction by Mats Dahllöf in Language and Literature</p
Short-chain n-alkanes in benthic mats and mosses from the Larsemann Hills, East Antarctica
No full textVariation in leaf colour (green, red and grey) of mosses and lake benthic mats in Antarctica is often linked to water stress and ultraviolet light (UV-B) exposure. Changes in the abundance of organic compounds, such as pectin and phenols, are associated with mechanisms protecting against desiccation and UV radiation. However, the function of n-alkanes, especially against UV radiation, is rarely examined. Here, gas chromatography–mass spectrometry and Fourier-transform infrared spectroscopy analyses were performed to study the variation in n-alkanes in freshwater lake benthic mats and mosses collected from the Larsemann Hills in East Antarctica. Stable isotopes of organic carbon and nitrogen, environmental DNA characterisation and microscopy-based analyses are used to estimate the presence of cyanobacteria, algae and diatoms in moss and benthic mat consortia. Variation in the short-chain (n-C17 to n-C20) versus long-chain (n-C21 to n-C30) n-alkanes in the mosses and benthic mats with their colour were noted. The research links the relative abundance of short-chain n-alkanes to the UV-B exposure and proposes that Antarctic mosses and benthic mats synthesise short-chain n-alkanes for protection against UV-B.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Sanitary Engineerin
Recycled carbon fibre mats for interlayer toughening of carbon fibre/epoxy composites
No full textExploring routes for the effective use of recycled carbon fibres (rCFs) is critical to close the loop in the life cycle of carbon fibres. This work demonstrated a potential of using rCFs for interlayer toughening of carbon fibre/epoxy composites. Nonwoven mats based on rCFs and commingled rCFs/Polyphenylene-sulfid (PPS) fibres were used to interlay a laminate, aiming to improve the mode-I and mode-II fracture toughness. The experimental results proved significant enhancements in the interlaminar fracture properties upon interleaving, with the rCF/PPS mats exhibiting a more prominent toughening effectiveness than the rCF mats. For example, the maximum increase in mode-I and mode-II fracture initiation energies of the laminates was 51% and 66%, respectively upon interleaving the rCF mats, and 220% and 105%, respectively by adding the rCFs/PPS mats. The fractography analysis proved that the main toughening mechanisms were fibre debonding and pulling-out for the rCF mats and fibre bridging for the commingled rCFs/PPS mats. The differences in the toughening mechanisms resulted in opposite effects of the interlayer/epoxy adhesion to the fracture toughness, i.e. an improved interlayer/epoxy adhesion increased the toughening effectiveness of the rCF mats, but negatively affected the toughening performance of the rCF/PPS mats.Structural Integrity & CompositesAerospace Manufacturing Technologie
Bioremediation of uranium contaminated waters using microbial mats, 2000
No full textMicrobial mats are complex, layered microbial communities dominated by cyanobacteria. Mats have been used successfully in the bioremediation of Pb, Cd, Cu, Zn, and Mn contaminated water. This study investigated the possible removal through reduction of soluble U( VI) present in the ionic complexed form in the presence of highly carbonated waters (240 mg/L) by microbial mats. Mats developed in the Bioremediation Laboratory at Clark Atlanta University were used in batch and water column studies. Preliminary studies showed optimum uranium uptake was produced by a 1:1:1 ratio of whole microbial mats, predominately cyanobacteria, and two bacterial groups isolated from the mats: Rhodospeudomonas and a mixed anaerobe group, dominated by sulfur reducers. X-ray absorption near-edge structure spectroscopy (XANES) revealed U(VI) was reduced to U(IV). Uranium removal rate was dependent on temperature, nutrients available, photosynthetic and reducing conditions, and amount of bacterial material per volume of solution
Remediation of mining water with cyanobacterial mats, 1992
No full textMicrobial mats, stimulated with ensiled grass clippings, have been developed to seguester heavy metals from contaminated water. Mixed populations of photosynthetic and heterotrophic bacteria, dominated by Oscillatoria, spp. were developed for metal tolerance and intergrated into a durable, self sustaining community of microbes attached to ensiled grass. Microbial components of the mat and water column effectively removed a number of toxic metals and metalloids from contaminated water by precipitation in the cell mass. Three applications of mats have been found to be effective in treating metal contaminated water. (1) Ponds with floating mats deposited metals at the surface removing 90 99% of the test metal. (2) Excised mats sequestered various metals from mixed solution (28 mg/1 per month of Cd). (3) Immobilized mats, composed of microbes attached to glass wool, in treatment systems employing flow through baffles and floater balls, removed 85 90% of the test metal
Stability of block mats under flow conditions
No full textBlock mattresses or block mats are, nowadays, very commonly applied as protection in a large range of applications either against flow or wave loads. Specifically, this large range of applications contains offshore pipeline protection and stabilization, erosion and scour protection, protection of embankments and river banks (slope protection). The reason why block mattresses are increasingly used in many applications as protection system is due to the following advantages compared to discrete-unit armour systems such as quarry stone or individually-placed blocks which are the enhanced stability that block mats have because of the virtue of connection between adjacent blocks and their properties of being able to be laid quickly and efficiently even under water.Civil Engineering and GeosciencesHydraulic Engineerin
Cellular and molecular mechanisms of bioremediation by microbial mats, 2000
No full textMicrobial mats were developed in the Bioremediation Laboratory at CAU and have been used successfully to remediate heavy metals from surface water. The cellular and molecular mechanisms involved in the bioremediation processes are not well understood. The objective of this study was to provide basic understanding of the cellular and molecular basis of heavy metal remediation by mats. The central hypotheses are: (1) that there are metal resistant and/or reducing bacteria in the mats; and (2) that mats produce specific biomolecules that bind to and sequester heavy metals from solution. The specific aims of this investigation were: (1) to isolate, identify, and characterize metal resistant and/or reducing bacteria from the mats, and (2) to isolate, purify, and characterize specific metal-binding biomolecules (bioflocculants) secreted by microbial mats. In this study a facultative, photoorganotrophic, purple, non-sulfur bacterium was isolated from the mixed-species microbial mats that were dominated by cyanobacteria and contained heterotrophic and purple autorophic bacteria. The isolated bacterium was a motile, gram negative rod. Electron micrographs of thin sections of the bacterium showed a lamellar intracytoplasmic membrane (1CM) system. Based on its morphology, nutrient requirements, absorption spectra, GC content, RAPD-PCR fingerprints, and partial sequences of 16 S rDNA, this isolate has been identified as a new strain of Rhodopseudomonas (Rhodopseudomonas mehrabi UME-1). This bacterium was resistant to high concentrations of several heavy metals (50-1000 mg/1) including As, Cd, Cr(III), Co, Cs, Cu(I), Cu(II), Fe, Hg(I), Mn, Pb, Sr, and Zn. The isolate reduced high concentrations (100 mg/1) of Cr(VI) and selenite. An extracellular, acidic polymer with metal binding and flocculating properties was also isolated from the microbial mats. Production of this acidic polysaccharide was highest at the end of the exponential growth phase, and decreased with increased formation of biofilm. The exopolymer has a high molecular weight (500,000 Dalton) and an isoelectric point of 4.2. Its carbohydrate composition was determined by GC/MS and fluorophore-assisted electrophoresis (FACE), and contained Arabinose, rhamnose, fticose, xylose, mannose, glucose, galactose, glucuronic acid, galacturonic acid, N-aetylglucosamine, and N-aetylgalactosamine. Rheological studies showed that bioflocculants produced a highly viscous solution, 1000 fold greater than the viscosity of glycerol at equivalent concentrations. Interaction of bioflocculant with mono- and divalent metals were examined using equilibrium and continuous flow dialysis. Bioflocculant was bound to 200-480 mg of metal per mg bioflocculant. Its strong metal binding and flocculating properties make this exopolysaccharide a good flocculating agent and may find useful commercial applications
Static and Dynamic Characteristics of Resilient Mats for Vibration Isolation of Railway Tracks
No full textAbstractThe paper presents essential static and dynamic properties characterizing resilient mats for vibration isolation of railway tracks. The attention was focused on under-ballast mats and slab-track mats used in the construction of railways. Referring to this type of mats, selected test procedures for determining the values of parameters describing static and dynamic characteristics were described. Basic classification of vibration isolation mats was presented in the paper. Moreover, the essential functional and operation features related to various types of mats were given. Some theoretical aspects concerning viscoelastic dynamic modelling of resilient track elements were also outlined. In order to characterize requirements and methodology of research for resilient mats in railway tracks, German Standards [1–3] were used herein
- …
