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101.
Lars Nilsson 《Drying Technology》2014,32(1):39-46
Dewatering on the paper machine takes place by gravity, suction, pressing, and evaporation. Optimizing the operation of the vacuum system is important, since the electricity consumption of the vacuum pumps might be one-fifth of the total electricity consumption of the paper machine. Vacuum dewatering involves large volumes of air penetrating the web. The present study presents four sets of measured air flow rates useful for designing industrial equipment. The mass flux of air increases with increasing applied vacuum and decreases with increasing basis weight. Paper technological parameters, such as fiber size and fiber flexibility, also influence the mass flux. 相似文献
102.
Dag Slotfeldt-Ellingsen Elisabeth Magnus Eric Ekern Egil Holtmon Lars Corneliussen 《Polymer Composites》1986,7(6):431-434
Entrapped air can commonly lead to large delaminations in thick walled sheet molding compound (SMC) products. In this work different sources of air entrapment in SMC are investigated. The critical process is shown to be the impregnation of the fibers. If no surface active additives are used, large volumes of air may be entrapped in this process, unless the viscosity of the compound is very low. In this situation of poor wetting, the viscosity of the compound during fiber impregnation will critically determine the interlaminar, tensile strength of the product. However, if surface active additives are used, the air escapes entrapment even at relatively high viscosities. The lowering of the viscosity, which is a side effect of the additives, has practically no importance under these conditions of good wetting. Large numbers of small air bubbles are also entrapped during the mixing of the components, but it is shown that these bubbles have very little effect on the mechanical properties of the finished part. 相似文献
103.
104.
Ann-Cathrine Lassas Lars E. Fagerholm Bengt G. Stelound Jan H. Nasman 《Polymer Composites》1993,14(1):1-6
The research reported in the article focuses on modifying glass fiber surfaces with polyacrylic acid (PAA) compounds. E-glass fibers were treated with aqueous polyacrylic acid solution. Polyacrylic acid exchanges its protons with the ions present in the glass surface. Hydrolyzed metal cations may form salt complexes with the dissociated polyacrylic acid. Angular dependent electron spectroscopy for chemical analysis (ESCA) demonstrated that the atomic concentrations of aluminum and calcium in the glass fiber surface were constant throughout the analyzed interval. The cation exchange property of glass fiber was studied using direct current plasma (DCP), which showed that both calcium and aluminum ions were extracted by low concentration polycrylic acid solutions. ESCA studies of were extracted by low concentrationb polyacrylic acid solutions. ESCA studies of the PAA-treated glass fiber showed that the amount of PAA of the glass surface increases with increased acid concentration. A broadened and shifted ESCA peak of the carbon (0 CO) indicates the formation of salt complexes between the polyacrylic acid and metal ions on the glass surface. Polyacrylie acid was modified by an esterification reaction with glycidyl acrylate (GA) in aqueous solution in order to insert organofuctional groups into the PAA chain. 相似文献
105.
Pengfei Liu Kacper Januchta Lars R. Jensen Mathieu Bauchy Morten M. Smedskjaer 《Journal of the American Ceramic Society》2020,103(2):944-954
Lithium aluminoborate glasses have recently been found to feature high resistance to crack initiation during indentation, but suffer from relatively low hardness and chemical durability. To further understand the mechanical properties of this glass family and their correlation with the network structure, we here study the effect of adding SiO2 to a 25Li2O–20Al2O3–55B2O3 glass on the structure and mechanical properties. Addition of silica increases the average network rigidity, but meanwhile its open tetrahedral structure decreases the atomic packing density. Consequently, we only observe a minor increase in hardness and glass transition temperature, and a decrease in Poisson's ratio. The addition of SiO2, and thus removal of Al2O3 and/or B2O3, also makes the network less structurally adaptive to applied stress, since Al and B easily increase their coordination number under pressure, while this is not the case for Si under modest pressures. As such, although the silica-containing networks have more free volume, they cannot densify more during indentation, which in turn leads to an overall decrease in crack resistance upon SiO2 addition. Our work shows that, although pure silica glass has very high glass transition temperature and relatively high hardness, its addition in oxide glasses does not necessarily lead to significant increase in these properties due to the complex structural interactions in mixed network former glasses and the competitive effects of free volume and network rigidity. 相似文献
106.
Janine Will Lars Schneider Dr. Jonathan Becker Jun.-Prof. Dr. Sabine Becker Andreas Miska Christopher Gawlig Prof. Dr. Siegfried Schindler 《Israel journal of chemistry》2020,60(10-11):999-1003
A new tripodal imine ligand tris(2-(propan-2-ylideneamino)ethyl)amine (imine3tren) was prepared in order to stabilize high valent iron-oxido complexes. Iron complexes were synthesized in template reactions from iron(II) salts, tris(2-aminoethyl)amine (tren) and acetone. Due to the reversibility of the imine formation, complexes with different ligands were obtained depending on the reaction conditions. Three complexes, [Fe(imine3tren)(OAc)2] ( 1 ), [Fe(imine3tren)(OAc)]OTf ( 2 ) and [(imine3tren)2Fe2(F)2](SbF6)2 ( 3 ), could be synthesized and structurally characterized. However, reactions with hydrogen peroxide, iodosobenzene or ozone did not lead to any kind of “oxygen adduct” complex that could be spectroscopically observed. 相似文献
107.
Photoreduction of Shewanella oneidensis Extracellular Cytochromes by Organic Chromophores and Dye‐Sensitized TiO2 下载免费PDF全文
Emma V. Ainsworth Dr. Colin W. J. Lockwood Dr. Gaye F. White Dr. Ee Taek Hwang Dr. Tsubasa Sakai Manuela A. Gross Prof. David J. Richardson Dr. Thomas A. Clarke Dr. Lars J. C. Jeuken Dr. Erwin Reisner Prof. Julea N. Butt 《Chembiochem : a European journal of chemical biology》2016,17(24):2324-2333
The transfer of photoenergized electrons from extracellular photosensitizers across a bacterial cell envelope to drive intracellular chemical transformations represents an attractive way to harness nature's catalytic machinery for solar‐assisted chemical synthesis. In Shewanella oneidensis MR‐1 (MR‐1), trans‐outer‐membrane electron transfer is performed by the extracellular cytochromes MtrC and OmcA acting together with the outer‐membrane‐spanning porin ? cytochrome complex (MtrAB). Here we demonstrate photoreduction of solutions of MtrC, OmcA, and the MtrCAB complex by soluble photosensitizers: namely, eosin Y, fluorescein, proflavine, flavin, and adenine dinucleotide, as well as by riboflavin and flavin mononucleotide, two compounds secreted by MR‐1. We show photoreduction of MtrC and OmcA adsorbed on RuII‐dye‐sensitized TiO2 nanoparticles and that these protein‐coated particles perform photocatalytic reduction of solutions of MtrC, OmcA, and MtrCAB. These findings provide a framework for informed development of strategies for using the outer‐membrane‐associated cytochromes of MR‐1 for solar‐driven microbial synthesis in natural and engineered bacteria. 相似文献
108.
Urban development and climate change are expected to have significant effects on urban stormwater runoff. In this study, the Dynamic Urban Water Simulation Model (DUWSiM) is applied to Dublin, Ireland, to explore urban runoff patterns under varying urban growth and climate scenarios. Results show that annual urban runoff could decrease by 3.0% from climate change and monthly runoff could increase by 30% in winter and decrease by 28% in summer. Results also indicate that urban growth could increase annual runoff by up to 15%. The combined effect of climatic and land-use change generated runoff may potentially increase annual totals from between 2.9% to 21%. Monthly changes in runoff totals could increase by up to 57%. Accommodating these variations in runoff between the scenarios, flexible decentralised systems such as green roofs and pervious pavements, have a vital role in increasing the adaptability and long term sustainability of water infrastructure. 相似文献
109.
Afaf Kamal-Eldin Lars Åke Appelqvist 《Journal of the American Oil Chemists' Society》1994,71(2):135-139
Seeds from different collections of cultivatedSesamum indicum Linn. and three related wild species [specifically,S. alatum Thonn.,S. radiatum Schum and Thonn. andS. angustifolium (Oliv.) Engl.] were studied for their oil content and fatty acid composition of the total lipids. The wild seeds contained
less oil (ca. 30%) than the cultivated seeds (ca. 50%). Lipids from all four species were comparable in their total fatty acid composition, with palmitic (8.2–12.7%), stearic
(5.6–9.1%), oleic (33.4–46.9%) and linoleic acid (33.2–48.4%) as the major acids. The total lipids from selected samples were
fractionated by thin-layer chromatography into five fractions: triacylglycerols (TAG; 80.3–88.9%), diacylglycerols (DAG; 6.5–10.4%),
free fatty acids (FFA; 1.2–5.1%), polar lipids (PL; 2.3–3.5%) and steryl esters (SE; 0.3–0.6%). Compared to the TAG, the four
other fractions (viz, DAG, FFA, PL and SE) were generally characterized by higher percentages of saturated acids, notably palmitic and stearic
acids, and lower percentages of linoleic and oleic acids in all species. Slightly higher percentages of long-chain fatty acids
(20∶0, 20∶1, 22∶0 and 24∶0) were observed for lipid classes other than TAG in all four species. Based on the fatty acid composition
of the total lipids and of the different acyl lipid classes, it seems thatS. radiatum andS. angustifolium are more related to each other than they are to the other two species. 相似文献
110.
Due to its high thermal stability and purely oxide ionic conductivity, yttria-stabilized zirconia (YSZ) is the most commonly used electrolyte material for solid oxide fuel cells (SOFCs). Standard electrolyte fabrication techniques for planar SOFCs involve wet ceramic techniques such as tape-casting or screen printing, requiring sintering steps at temperatures above 1300 °C. Plasma spraying (PS) may provide a more rapid and cost efficient method to produce SOFCs without sintering. High-temperature sintering requires long processing times and can lead to oxidation of metal alloys used as mechanical supports, or to detrimental interreactions between the electrolyte and adjacent electrode layers. This study investigates the use of spin coated sol gel derived YSZ precursor solutions to fill the pores present in plasma sprayed YSZ layers, and to enhance the surface area for reaction at the electrolyte-cathode interface, without the use of high-temperature firing steps. The effects of different plasma conditions and sol concentrations and solid loadings on the gas permeability and fuel cell performance have been investigated. 相似文献