Search results for "engineering.material"
showing 10 items of 2352 documents
Review on Physiological Effects of Vermicomposts on Plants
2020
Vermicompost is a type of organic fertilizer produced by earthworms and their symbiotic microorganisms. In addition to nutrient-rich organic fraction, vermicomposts also contain plant-available soluble minerals as well as substances with plant growth-regulating activity. In order to promote understanding on beneficial effects of vermicompost in different farming systems, the aim of the present review is to analyze possible mechanisms of vermicompost action on plants. After overview of plant growth-affecting activity of vermicomposts at the level of seed germination and vegetative growth, detailed analysis is dedicated to physiological effects associated with mineral nutrition: changes in bo…
Carbohydrates as Chemical Constituents of Biowaste Composts and their Humic and Fulvic Acids
1995
The decomposition of organic matter of source-separated biowaste during composting was followed during 18 months. Compost samples were fractionated into three parts: (i) hot water soluble extract (HWE) (ii) bitumen fraction and (iii) humic substances (humic acids (HA) and fulvic acids (FA)). Original compost samples and the HA and FA fractions were hydrolyzed with sulfuric acid for hexoses and pentoses. Quantitative spectrophotometric and qualitative GC/MS analyses of monosaccharides as trimethylsilyl ethers of the corresponding alditols were carried out.During composting, the amount of HA in the organic matter of the compost increased, the amounts of HWE and bitumen decreased and the amoun…
Cation Diffusion and Segregation at the Interface between Samarium-Doped Ceria and LSCF or LSFCu Cathodes Investigated with X-ray Microspectroscopy
2017
The chemical compatibility between electrolytes and electrodes is an extremely important aspect governing the overall impedance of solid-oxide cells. Because these devices work at elevated temperatures, they are especially prone to cation interdiffusion between the cell components, possibly resulting in secondary insulating phases. In this work, we applied X-ray microspectroscopy to study the interface between a samarium-doped ceria (SDC) electrolyte and lanthanum ferrite cathodes (La0.4Sr0.6Fe0.8Cu0.2O3(LSFCu); La0.9Sr0.1Fe0.85Co0.15O3(LSCF)), at a submicrometric level. This technique allows to combine the information about the diffusion profiles of cations on the scale of several micromet…
Cu-B alloy - analysis of use possibility as fuel cell cathode catalyst
2016
In recent years there has been a development of non-conventional and renewable sources of energy. One such sources of energy are fuel cells. Fuel cells are ecological and high efficiency sources of electric energy. However, the use of fuel cells on a large scale is limited, mainly by the high cost of catalysts. Platinum is most commonly used as the catalyst. But due to the high price of platinum there’s a need for finding other catalysts. Replacement of platinum will contribute to the fast development of green energy sources. This paper presents a study of possibility of using Cu-B alloy as catalyst for oxygen electrode in fuel cells. Researches were done in glass vessel, on a copper electr…
Inhibitoren der Korrosion 27 (1). Inhibitoren der Korrosion von Kupfer - Gibt es eine Struktur-Wirkungsbeziehung?
1982
Mehr als 570 Verbindungen der unterschiedlichsten Struktur wurden unter Standardbedingungen im “Schuttelversuch” und pH-statisch auf ihre Korrosionsschutzwirkung gegenuber Kupfer getestet und mit Hilfe eines Computers ausgewertet. Die erhaltenen Ergebnisse stehen relativ haufig in Ubereinstimmung mit Dem “Hart-Weich-Konzept” von Pearson. Eine gezielte Synthese von Inhibitoren, die sich in diesem Konzept orientiert, ist jedoch nicht moglich. Inhibitors of corrosion 27 (1). Inhibitors of the corrosion of copper Does there exist a structure-effect-relation? Over 570 compounds of greatly varying structure have been tested under controlled conditions in agitation and pH-stat experiments designed…
Electro-conversion as sustainable method for the fine chemical production from the biopolymer lignin
2018
Lignin, one of the most abundant polymers in nature, qualifies itself by the polyphenolic structure as potential renewable feedstock for the production of bio-based aromatic fine chemicals. However, the natural complexity and degradation stability of lignin make the depolymerization a highly challenging task. Several efforts have been pursued for the selective degradation of the biopolymer into suitable compounds. However, there are only a few technical approaches for the degradation of lignin to aromatic fine chemicals. Organic electrosynthesis is the synthetic method that enables the direct use of electricity for the production of valuable compounds. Moreover, electro-organic synthesis re…
On Demand One-Pot Mild Preparation of Layered Double Hydroxides and Their Hybrid Forms: Advances through the Epoxide Route.
2019
Epoxide ring opening driven alkalinization process was explored with the aim of preparing layered double hydroxide (LDH) phases on demand, at room temperature. Employing iodide as nucleophilic agent, the precipitation reaction can be driven under much lower halide concentrations. This scenario favors the selective intercalation of concomitant bulky oxo anions as nitrate or perchlorate in the LDH products, allowing for the one-pot synthesis of an LDH able to delaminate in formamide. Even large dicarboxylic acids, - O2 C-(CH2 )n -CO2 - , with n up to 8, can be quantitively intercalated within the growing LDH phase, providing a versatile one-pot route for hybrid LDHs as well. Under the mild co…
Hydrothermal degradation of biobased poly(butylene succinate)/nanofibrillated cellulose composites
2021
Biobased polymers and composites have gained increased global attention due to their abundance, renewability, and biodegradability. Natural fillers such as cellulose-based fillers improve the mechanical properties of biopolymers, extending their application range, while maintaining the eco-friendly characteristics of the materials. Mowing towards engineering applications, requirements imposed on materials’ durability with regard to their environmental impact and high performance is necessary. Variations of ambient humidity and temperature could essentially reduce the service lifetime of biobased polymer composites. This study is focused on the hydrothermal degradation of poly(butylene succi…
Reactive surface coatings based on polysilsesquioxanes: defined adjustment of surface wettability.
2009
We have investigated a generally applicable protocol for a substrate-independent reactive polymer coating that offers interesting possibilities for further molecular tailoring via simple wet chemical derivatization reactions. Poly(methylsilsesquioxane)-poly(pentafluorophenyl acrylate) hybrid polymers have been synthesized by RAFT polymerization, and stable reactive surface coatings have been prepared by spin-coating on the following substrates: Si, glass, gold, PMMA, PDMS, and steel. These coatings have been used for a defined adjustment of surface wettability by surface-analogous reaction with various amines (e.g., glutamic acid to obtain hydrophilic surfaces (Theta(a) = 18 degrees) or per…
Substrate-Independent Stable and Adherent Reactive Surface Coatings and their Conversion with Amines
2007
To create stable, adherent and reactive surface coatings, a hybrid polymer composed of poly(methylsilsesquioxane) (PMSSQ) and poly(pentafluorophenyl acrylate) PFPA with a M n of 32000 g/mol was prepared by a RAFT polymerization procedure. These hybrid polymer has been used for coating experiments. The PFPA part enabled a variable functionalization of the coating afterwards. The stability on various substrates (e.g. glass, PMMA, steel) was tested in an ISO tape test. These reactive surface coatings were modified using different amines, such as amino-terminated PEG, dodecyl amine and N-isopropyl amine. The conversion was analyzed by FT-IR and contact angle measurements.