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Organic Substances (organic + substance)
Selected AbstractsBook Review: Refractory Organic Substances in the Environment.INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3-4 2003B. Hock, By H. Frimmel, G. Abbt-Braun, H. D. Lüdemann, K. G. Heumann, M. Spiteller No abstract is available for this article. [source] Nanometer-Scale Mapping of Elastic Modules in Biogenic Composites: The Nacre of Mollusk ShellsADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Haika Moshe-Drezner Abstract In this study, a newly developed nanoscale modulus mapping is applied in order to visualize the 2D-distribution of mechanical characteristics in the aragonitic nacre layer of Perna canaliculus (green mussel) shells. Modulus maps provide lateral resolution of about 10 nm. They allow the aragonitic mineral (CaCO3) tablets and the interfaces between them to be clearly resolved, which are filled by an organic substance (mainly beta-chitin). The experimental data are compared with finite element simulations that also take into account the tip radius of curvature and the thickness of organic layers, as measured by means of scanning electron microscopy with back-scattered electrons. Based on this comparison, the Young modulus of beta-chitin is extracted. The obtained number, E, = 40 GPa, is higher than previously evaluated. The collected maps reveal that the elastic modules in the nacre layer change gradually across the ceramic/organic interfaces within a spatial range four times wider than the thickness of the organic layers. This is possibly due to inhomogeneous distribution of organic macromolecules within ceramic tablets. According to the data, the concentration of macromolecules gradually increases when approaching the organic/ceramic interfaces. A behavior of this type is unique to biogenic materials and distinguishes them from synthetic composite materials. Finally, three possible mechanisms that attempt to explain why gradual changes of elastic modules significantly enhance the overall resistance to fracture of the nacre layer are briefly discussed. The experimental findings support the idea that individual ceramic tablets, comprising the nacre, are built of the compositionally and functionally graded ceramic material. This sheds additional light on the origin of the superior mechanical properties of biogenic composites. [source] Exergetic efficiency and options for improving sewage sludge gasification in supercritical waterINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2007Edgar Gasafi Abstract The present article deals with an exergy analysis of a process under development for the gasification of biomass in supercritical water (supercritical water gasification, SCWG). This process is aimed at generating hydrogen out of the biogenic feedstock sewage sludge. The principle of the process is based on making use of the modifications of specific physical and chemical properties of water above the critical point (T=374°C, p=221 bar). These properties allow for a nearly complete conversion of the organic substance contained in the feed material into energy-rich fuel gases, containing hydrogen, carbon dioxide and methane. Based on a steady-state model of the process, exergy flow rates are calculated for all components and a detailed exergy analysis is performed. From the exergetic variables, options to improve the individual plant components as well as the overall plant are derived. The components with the highest proportion of exergy destruction in the complete process are identified and possibilities of improving them and the complete system in order to increase the overall efficiency are demonstrated. The combustion chamber necessary for heat supply is found to be the component with the highest proportion of exergy destruction of the complete plant. Moreover, the components of air preheater, reactor contribute significantly to the exergy destruction of the complete system. Copyright © 2006 John Wiley & Sons, Ltd. [source] Olive oil production on bronze age Crete: nutritional properties, processing methods and storage life of Minoan olive oilOXFORD JOURNAL OF ARCHAEOLOGY, Issue 1 2002F.R. Riley Archaeological studies on olive oil produced in Crete in the Bronze Age focus primarily on aspects such as the period when olive cultivation became widespread, the number of olive trees cultivated, or the quantity of oil stored in the Minoan palaces. Olive oil is however an organic substance, a perishable product, the nutritional and storage properties of which are determined by environmental, agronomic, processing and storage conditions. In this paper archaeological, environmental and biochemical evidence is combined to present a comprehensive picture of the potential quality, nutritional and storage properties of Minoan olive oil. The comparative evidence presented suggests that Minoan olive oil was equal in quality to the cold-pressed virgin olive oils produced today, and as such, the oil was nutritionally important in the Bronze Age and a valuable trade commodity. [source] Contrast in Fluid Metallogeny between the Tianmashan Au-S Deposit and the Datuanshan Cu Deposit in Tongling, Anhui ProvinceACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2003DU Yangsong Abstract, A comprehensive contrast of ore-forming geological background and ore-forming fluid features, especially fluid ore-forming processes, has been performed between the Tianmashan and the Datuanshan ore deposits in Tongling, Anhui Province. The major reasons for the formation of the stratabound skarn Au-S ore deposit in Tianmashan and the stratabound skarn Cu ore deposit in Datuanshan are analyzed in accordance with this contrast. The magmatic pluton in Tianmashan is rich in Au and poor in Cu, but that in Datuanshan is rich in Cu and Au. The wallrock strata in Tianmashan contain Au-bearing pyrite layers with some organic substance but those in Datuanshan contain no such layers. Moreover, the ore-forming fluids in Tianmashan are dominantly magmatic ones at the oxide and sulfide stages, but those with high content of Cu in Datuanshan are mainly groundwater fluids. In addition, differences in compositional evolution and physicochemical condition variation of the ore-forming fluids result in gradual dispersion of Cu or Au in the late stage of the fluid ore-forming process. This is also an important metallogenic factor for the stratabound skarn Au-S ore deposit in Tianmashan and stratabound skarn Cu ore deposit in Datuanshan. [source] Decomposition of a Lignin Model Compound under Hydrothermal ConditionsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2007Wahyudiono Abstract Lignin, which is the second most abundant polymeric aromatic organic substance in wood biomass after cellulose, and contains many oxygen-based functional groups, has been proposed as an alternative source of chemical compounds. Guaiacol, a model compound for lignin, was reacted in supercritical water using a batch-type reactor at temperatures of 653,673,K and various pressures under an argon atmosphere. The effects of temperature and reaction time at the same pressure were combined into a single severity parameter that was used to monitor the decomposition of guaiacol to its derived compounds. The main products in aqueous solution were catechol, phenol, and o -cresol. The amounts present approached 40.73,wt,%, 14.18,wt,%, and 4.45,wt,%, respectively. With an increase in the reaction time at the same conditions, the amount of guaiacol decreased and the quantity of derived compounds of guaiacol increased. Based on the experimental results, a reaction mechanism for the decomposition of guaiacol was proposed. The process investigated in this study may form the basis for an efficient method of wood biomass decomposition. [source] Application of a Carbon Paste Electrode Modified with a Schiff Base Ligand to Mercury Speciation in WaterELECTROANALYSIS, Issue 11 2005Montserrat Colilla Abstract A carbon paste electrode, modified with benzylbisthiosemicarbazone is used for mercury speciation in water samples. Mercury ion is selectively accumulated on the electrode surface at open circuit and its analysis was performed by cyclic voltammetry or square-wave voltammetry (SWV). A detection limit of 8,,g L,1 (3,) was found for 15,min of accumulation using SWV as measurement technique. The effect of several metallic ions and organic substances on voltammetric signal is examined. For speciation purposes, a ligand competition methodology between ligands in solution and electrode is used. Model mercury complexes are characterized as a function of their dissociation kinetics. The method was applied to mercury speciation in water samples from the Jarama River in Madrid. [source] Arsenic speciation in natural and contaminated waters using CZE with in situ derivatization by molybdate and direct UV-detectionELECTROPHORESIS, Issue 6 2009Olga S. Koshcheeva Abstract A simple and sensitive procedure for simultaneous determination of arsenate, arsenite, monomethylarsonate and dimethylarsinate (DMA) ions in waters using CZE with chemical derivatization in situ and UV-detection at 250,nm was developed. The separation was performed in a fused-silica capillary using solution containing sodium molybdate and sodium perchlorate as electrolyte. Molybdate forms heteropolycomplexes with arsenic species in low acidic media, while sodium perchlorate masks silicate ion. The analysis conditions were optimized; the best results were achieved with the electrolyte consisting of 10,mM Na2MoO4 and 10,mM NaClO4 at pH 3.0 using negative voltage and pneumatic injection of the sample. Nevertheless, the signal of arsenite ion was not detected, probably because of its instability. Arsenite ion was quantified as a difference between arsenate ion contents after and before oxidation by bromine water. The detection limits for the fresh water at the level of 5.0,,g/L for AsIII and AsV, 16,,g/L for DMA and 20,,g/L for MMA were achieved. The reproducibility varied in the range of 0.06,0.25 relative units. To reduce the interferences of the sample salinity an addition of organic substances and isotachophoretic effect were used. [source] Non-enzymatic hydrolysis of fluorescein diacetate (FDA) in a Mediterranean oak (Quercus ilex L.) litterEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008E. Alarcón-Gutiérrez Summary We show the presence of interfering substances when the total microbial activity in litter samples is measured with fluorescein diacetate (FDA), and we propose some methodological modifications to avoid such interference. Three distinct litter layers (the OhLn, the OhLv and the OhLf) of evergreen oak (Quercus ilex L.) were characterized by 13C CPMAS NMR and the spectra show that the recalcitrant aromatic and phenolic compounds increase with the degree of degradation of litter. A wide range of sources of interference in the hydrolysis of FDA was found. To understand the origin of this interference, sterilized litter materials (i.e. ,-irradiated or autoclaved) and a wide range of organic substances (i.e. amino acids, glucose, sorbitol and organic humic acids) were investigated. Insignificant differences on the FDA hydrolysis activity (FDA activity) were found in the ,-irradiated and non-irradiated OhLn litter, indicating that ,-irradiation does not destroy enzymes. Conversely, after heat-sterilization of litter, samples showed FDA activity corresponding to 60, 34.8 and 30.8% (in the OhLn, the OhLv and the OhLf layers, respectively) of that of control litters. This indicates the presence of non-enzymatic interfering substances in the FDA assays. As the humification and litter depth increased, hydrolysis of FDA due to interferences decreased, indicating degradation and/or chelation of interfering substances. We hypothesize that lysine, arginine, histidine and cysteine are mainly responsible for the hydrolysis of FDA. We suggest that the use of phosphate buffer (50 mm, pH 7.0) with incubation <,30 minutes, in combination with a temperature between 30 and 40°C, produces insignificant interference in the determination of the final FDA activity in litter samples. [source] Power Generation and Electrochemical Analysis of Biocathode Microbial Fuel Cell Using Graphite Fibre Brush as Cathode MaterialFUEL CELLS, Issue 5 2009S.-J. You Abstract To improve cathodic efficiency and sustainability of microbial fuel cell (MFC), graphite fibre brush (GFB) was examined as cathode material for power production in biocatalysed-cathode MFC. Following 133-h mixed culturing of electricity-producing bacteria, the MFC could generate a reproducible voltage of 0.4,V at external resistance (REX) of 100,,. Maximum volumetric power density of 68.4,W,m,3 was obtained at a current density of 178.6,A,m,3. Upon aerobic inoculation of electrochemically active bacteria, charge transfer resistance of the cathode was decreased from 188 to 17,, as indicated by electrochemical impedance spectroscopy (EIS) analysis. Comparing investigations of different cathode materials demonstrated that biocatalysed GFB had better performance in terms of half-cell polarisation, power and Coulombic efficiency (CE) over other tested materials. Additionally, pH deviation of electrolyte in anode and cathode was also observed. This study provides a demonstration of GFB used as biocathode material in MFC for more efficient and sustainable electricity recovery from organic substances. [source] Approaches for derivation of environmental quality criteria for substances applied in risk assessment of discharges from offshore drilling operationsINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 2 2008Dag Altin Abstract In order to achieve the offshore petroleum industries "zero harm" goal to the environment, the environmental impact factor for drilling discharges was developed as a tool to identify and quantify the environmental risks associated with disposal of drilling discharges to the marine environment. As an initial step in this work the main categories of substances associated with drilling discharges and assumed to contribute to toxic or nontoxic stress were identified and evaluated for inclusion in the risk assessment. The selection were based on the known toxicological properties of the substances, or the total amount discharged together with their potential for accumulation in the water column or sediments to levels that could be expected to cause toxic or nontoxic stress to the biota. Based on these criteria 3 categories of chemicals were identified for risk assessment the water column and sediments: Natural organic substances, metals, and drilling fluid chemicals. Several approaches for deriving the environmentally safe threshold concentrations as predicted no effect concentrations were evaluated in the process. For the water column consensus were reached for using the species sensitivity distribution approach for metals and the assessment factor approach for natural organic substances and added drilling chemicals. For the sediments the equilibrium partitioning approach was selected for all three categories of chemicals. The theoretically derived sediment quality criteria were compared to field-derived threshold effect values based on statistical approaches applied on sediment monitoring data from the Norwegian Continental Shelf. The basis for derivation of predicted no effect concentration values for drilling discharges should be consistent with the principles of environmental risk assessment as described in the Technical Guidance Document on Risk Assessment issued by the European Union. [source] Fluorous Surface-Active Distannoxane CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Akihiro Orita Abstract Fluorous distannoxanes (XRf2SnOSnRf2X)2,n,H2O (Rf=C6F13C2H4) (1: X=C8F17SO3, n=10; 4: X=Cl, n=0) (1) catalyze the Mukaiyama aldol reaction and the allylation of aldehydes with tetraallyltin at room temperature in fluorous/organic biphasic solvent systems, in which the reactions proceed more rapidly than in a single organic or fluorous solvent. Due to the unique surface activity of 1, the catalyst, organic substrate(s), and reagent(s) are distributed in both organic and fluorous phases to facilitate smooth reactions. Upon dilution with toluene after the reaction, the catalyst concentrates to the fluorous phase, while the organic substances migrate to the organic phase to effect facile catalyst recovery and recycling. By virtue of such a unique solvophilicity, a new version of fluorous biphase technology has been developed. [source] An effective iodide formulation for killing Bacillus and Geobacillus spores over a wide temperature rangeJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2004N. Kida Abstract Aims:, To develop a sporicidal reagent which shows potent activity against bacterial spores not only at ambient temperatures but also at low temperatures. Methods and Results:, Suspension tests on spores of Bacillus and Geobacillus were conducted with the reagent based on a previously reported agent (N. Kida, Y. Mochizuki and F. Taguchi, Microbiology and Immunology 2003; 47: 279,283). The modified reagent (tentatively designated as the KMT reagent) was composed of 50 mmol l,1 EDTA-2Na, 50 mmol l,1 ferric chloride hexahydrate (FeCl3·6H2O), 50 mmol l,1 potassium iodide (KI) and 50% ethanol in 0·85% NaCl solution at pH 0·3. The KMT reagent showed significant sporicidal activity against three species of Bacillus and Geobacillus spores over a wide range of temperature. The KMT reagent had many practical advantages, i.e. activity was much less affected by organic substances than was sodium hypochlorite, it did not generate any harmful gas and it was stable for a long period at ambient temperatures. The mechanism(s) of sporicidal activity of the KMT reagent was considered to be based on active iodine species penetrating the spores with enhanced permeability of the spore cortex by a synergistic effect of acid, ethanol and generated active oxygen. Conclusions:, The data suggest that the KMT reagent shows potent sporicidal activity over a wide range temperatures and possesses many advantages for practical applications. Significance and Impact of the Study:, The results indicate development of a highly applicable sporicidal reagent against Bacillus and Geobacillus spores. [source] Efficiency of naphthalene biodegradation by Pseudomonas putida G7 in soilJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2004Andrei E Filonov Abstract The efficiency of naphthalene degradation by Pseudomonas putida G7 in soil was assessed using a mathematical model. The number of microorganisms and the concentration of naphthalene in soil samples were monitored. The feasibility of a spectrofluorometric method for naphthalene assay in soil samples was compared with high pressure liquid chromatography. A proposed mathematical model described the growth of the naphthalene-degrading strains and the consumption of substrates (naphthalene, naphthalene degradation intermediates and soil organic substances) in soil. To describe the growth kinetics of microorganisms having high affinity to substrates with low solubility, two differential equations with substrate exponent 2/3 were proposed. These equations were used to describe utilization of soil organic matter. The model parameters characterize the growth rates for different substrates and respective yield coefficients, specific bacterial death and adaptation rates, and also the rates of PAHs degradation and evaporation. These characteristics can be used in choosing the bacterial strains for biopreparations and efficient clean-up biotechnology of polluted soils. Copyright © 2004 Society of Chemical Industry [source] Reactivation of spent Pd/AC catalyst by supercritical CO2 fluid extractionAICHE JOURNAL, Issue 9 2009Xiaoxin Zhang Abstract In this article, we reported a nondestructive and environmentally friendly method for the reactivation of a spent Pd/AC catalyst for the hydrogenation of benzoic acid by using supercritical CO2 (scCO2) fluid extraction. The effects of reactivation conditions, such as extraction temperature, pressure, CO2 flow rate, and time, on the activity of the reactivated Pd/AC catalyst, were presented. The catalyst was characterized by N2 physisorption, laser particle size analysis, and transmission electron spectroscopy, and the liquid extract was analyzed by GC-MS. It is found that scCO2 fluid extraction was very efficient in eliminating organic substances blocking the pores of the catalyst, while did not affect noticeably the granule size of the catalyst and the particle size of Pd. The reactivated Pd/AC catalyst regained more than 70% of the activity of the fresh 5.0 wt % Pd/AC catalyst, and has been successfully used in an industrial unit for the hydrogenation of benzoic acid. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Compound-specific stable-isotope (,13C) analysis in soil scienceJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2005Bruno Glaser Abstract This review provides current state of the art of compound-specific stable-isotope-ratio mass spectrometry (,13C) and gives an overview on innovative applications in soil science. After a short introduction on the background of stable C isotopes and their ecological significance, different techniques for compound-specific stable-isotope analysis are compared. Analogous to the ,13C analysis in bulk samples, by means of elemental analyzer,isotope-ratio mass spectrometry, physical fractions such as particle-size fractions, soil microbial biomass, and water-soluble organic C can be analyzed. The main focus of this review is, however, to discuss the isotope composition of chemical fractions (so-called molecular markers) indicating plant- (pentoses, long-chain n-alkanes, lignin phenols) and microbial-derived residues (phospholipid fatty acids, hexoses, amino sugars, and short-chain n-alkanes) as well as other interesting soil constituents such as "black carbon" and polycyclic aromatic hydrocarbons. For this purpose, innovative techniques such as pyrolysis,gas chromatography,combustion,isotope-ratio mass spectrometry, gas chromatography,combustion,isotope-ratio mass spectrometry, or liquid chromatography,combustion,isotope-ratio mass spectrometry were compared. These techniques can be used in general for two purposes, (1) to quantify sequestration and turnover of specific organic compounds in the environment and (2) to trace the origin of organic substances. Turnover times of physical (sand < silt < clay) and chemical fractions (lignin < phospholipid fatty acids < amino sugars , sugars) are generally shorter compared to bulk soil and increase in the order given in brackets. Tracing the origin of organic compounds such as polycyclic aromatic hydrocarbons is difficult when more than two sources are involved and isotope difference of different sources is small. Therefore, this application is preferentially used when natural (e.g., C3-to-C4 plant conversion) or artificial (positive or negative) 13C labeling is used. Substanzspezifische Stabilisotopenanalyse (,13C) in der Bodenforschung Dieser Artikel fasst den Stand der Forschung bezüglich der substanzspezifischen Stabilisotopenanalyse (,13C) zusammen. Innovative Anwendungen und ein Ausblick für künftige Forschungsaktivitäten werden anhand von Fallbeispielen gegeben. Zunächst wird die ökologische Bedeutung von stabilen C-Isotopen kurz erläutert. Daran schließt sich ein methodischer Teil an, in welchem die verschiedenen Techniken gegenüber gestellt werden. Analog zu ,13C-Messungen der Feinerde mittels Elementaranalysator-Isotopenverhältnis-Massenspektrometrie können physikalisch isolierte Fraktionen (z.,B. Korngrößenfraktionen, mikrobielle Biomasse, DOC) analysiert werden. Der Schwerpunkt dieses Übersichtsartikels liegt jedoch in der Diskussion der C-Isotopensignatur chemischer Fraktionen (sog. Biomarker), welche Rückschlüsse auf Herkunft und Dynamik pflanzlicher (Pentosen, langkettige n-Alkane, Ligninphenole) und mikrobieller Rückstände (Phospholipidfettsäuren, Hexosen, Aminozucker und kurzkettige n-Alkane) sowie anderer interessanter Substanzen im Boden erlaubt wie z.,B. ,Black Carbon" und polyzyklische aromatische Kohlenwasserstoffe. Zu diesem Zweck kommen innovative Techniken zum Einsatz wie z.,B. Pyrolyse-Gaschromatographie-Isotopenverhältnismassenspektrometrie, Gaschromatographie-Verbrennungs-Isotopenverhältnismassenspektrometrie und Flüssigkeitschromatographie-Oxidations-Isotopenverhältnismassenspektrometrie. Innovative ökologische Anwendungen werden erläutert, welche sich prinzipiell in zwei Kategorien einteilen lassen: (1) Quantifizierung der Sequestrierung und des Umsatzes dieser Verbindungen in der Umwelt; (2) Untersuchung der Herkunft spezifischer organischer Substanzen. Umsatzzeiten physikalischer (Sand < Schluff < Ton) und chemischer Fraktionen (Lignin < Phospholipidfettsäuren < Aminozucker , Zucker) sind generall kleiner als jene der gesamten organischen Substanz in der Feinerde und nehmen in der in Klammern angegebenen Reihenfolge zu. Die Untersuchung der Herkunft organischer Substanzen (z.,B. polyzyklischer aromatischer Kohlenwasserstoffe) ist problematisch, weil die Unterschiede der Isotopensignatur verschiedener Quellen gering sind und meist mehr als zwei Quellen zur Isotopensignatur des untersuchten Biomarkers beitragen. Deswegen sollte die Untersuchung der Herkunft organischer Substanzen auf Tracer-Experimente beschränkt werden, wie z.,B. nach natürlicher (C3-C4-Pflanzenwechsel) bzw. künstlicher (13C-An- oder -Abreicherung) Markierung. [source] "The principles of rational agriculture" by Albrecht Daniel Thaer (1752,1828).JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2003An approach to the sustainability of cropping systems at the beginning of the 19th century Abstract The identification of quantitative fertility indicators for evaluating the sustainability of cropping and farming systems has become a major issue. This question has been extensively studied by the German agronomist Albrecht Daniel Thaer at the beginning of the 19h century. In this paper Thaer's work is set in its historical background, from the end of the 16th century (Palissy, 1580) to the middle of the 19th century (Liebig, 1840). Then the paper focuses on Thaer's quantitative and complex fertility scale (expressed in "fertility degrees"), which was based on soil properties, on the requirement of nutrients by plants, and on the cropping system (including crop rotation). Thaer expressed soil fertility and economic results as a function of rye production in "scheffel of rye per journal" (ca. 200 kg per hectare). He also proposed a scale to describe the intrinsic fertility of soil. Thaer used this approach to assess the effect of major German cropping systems on soil fertility. He applied it to eight theoretical systems and nine existing systems in a true modeling approach. Thaer completed the fertility evaluation for the nine existing systems with a detailed economical analysis commenting the limits and potentialities of each system. Thaer's approach was used with success during half a century as it combined numerous empirical findings on soils and fertilization with organic substances in a sophisticated model. Unfortunately and despite effective practical applications, the scientific foundations of Thaer's "Humus Theory" proved definitively false as soon as 1840 when Sprengel and Liebig published on mineral nutrition of plants. Thaer's work deserves to be rediscovered since it approaches the modern issue of the sustainability of cropping and farming systems. "Grundsätze der rationalen Landwirtschaft" von Albrecht Daniel Thaer (1752,1828). Ein Ansatz zur Nachhaltigkeit von Anbausystemen zu Beginn des 19. Jahrhunderts Die Identifizierung von quantitativen Fruchtbarkeitsindikatoren, mit denen die Nachhaltigkeit von Anbau- und Bewirtschaftungssystemen evaluiert werden kann, ist ein wichtiges Thema geworden. Diese Frage wurde zu Beginn des 19. Jahrhunderts von dem deutschen Agronomen Albrecht Daniel Thaer intensiv untersucht. In diesem Beitrag wird die Arbeit von Thaer in ihren historischen Zusammenhang gestellt, d.h. vom Ende des 16. Jahrhunderts (Palissy (1580)) bis zur Mitte des 19. Jahrhunderts (Liebig (1840)). Anschließend wird Thaers komplexe quantitative Fruchtbarkeitsskala (ausgedrückt in "Fruchtbarkeitsgraden") vorgestellt, die auf Bodeneigenschaften, dem Nährstoffbedarf der Pflanzen und dem Anbausystem (einschließlich der Fruchtfolge) basierte. Thaer formulierte die Bodenfruchtbarkeit und ökonomische Resultate einer Kultur oder einer Fruchtfolge in "Scheffel Roggen pro Morgen" (ca. 200 kg pro Hektar). Thaer schlug auch eine Skala vor, um den inhärenten Wert des Bodens zu beschreiben. Er benutzte diesen Ansatz, um die Auswirkungen von in Deutschland verbreiteten Anbausystemen auf die Bodenfruchtbarkeit zu bestimmen. Er wandte diesen Ansatz auf acht theoretische und neun reale Systeme an, d.h. mit einem echten Modellierungs-Ansatz. Er vervollständigte die Beurteilung der Fruchtbarkeit der neun existierenden Systeme mit einer detaillierten wirtschaftlichen Analyse, wobei er die Grenzen und die Leistungsfähigkeit jedes Systems kommentierte. Thaers Ansatz wurde ein halbes Jahrhundert lang mit Erfolg benutzt, da er zahlreiche empirische Beobachtungen über Böden und Düngung mit organischen Substanzen in einem komplexen Modell vereinigt. Trotz erfolgreicher praktischer Anwendung erwiesen sich die wissenschaftlichen Grundlagen von Thaers "Humustheorie" schon 1840 definitiv als falsch, als Sprengel und Liebig ihre Arbeiten über die mineralische Ernährung der Pflanzen veröffentlichten. Thaers Werk verdient es, neu entdeckt zu werden, da es die aktuelle Frage nach der Nachhaltigkeit von Anbau- und Bewirtschaftungssystemen behandelt. [source] Production of Ceramic Green Bodies Using a Microwave-Reactive Organic BinderJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2007Kimiyasu Sato Because the pyrolysis of organic substances can result in the emission of harmful pollutant gases, a reduction in the use of organic binders is one aim of today's ceramics industry. A novel ceramic-forming process was developed that requires considerably less organic binder than conventional techniques. The process involves immobilizing reactive molecules on the surfaces of the particles, which on subsequent irradiation with microwaves, form bridges that bind the entire particle assembly together. The chemical forces involved produce strong bonds, resulting in a significant reduction in the amount of organic binder that is required to maintain the shape of the ceramic green body. This method will help to decrease emissions of harmful gases produced from pyrolysis of the binder. [source] Sediment dynamics and pollutant mobility in rivers: An interdisciplinary approachLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 1 2004Ulrich Förstner Abstract Characteristic dynamic features of sediment-related processes in rivers include dramatic effects of stormwater events on particle transport, rapid and far-reaching effects of sulphide oxidation during resuspension, and biological accumulation and potential release of toxic chemicals. Pollutant mobility is the net result of the stabilizing and mobilizing effects in both hydraulic and chemical fields. In practice, emphasis has to be given to fine-grained sediments and suspended matter as these materials exhibit large surface areas and high sorption capacities. Organic materials are highly reactive. Degradation of organic matter will induce oxygen depletion and might enhance formation of flocs and biofilms. Study of variations of sediment and water chemistry should predominantly include changes of pH and redox conditions, competition of dissolved ions and processes such as complexation by organic substances. Major questions relate to the potential reduction of sorption sites on minerals and degradation of organic carrier materials. All these processes will influence solution/solid equilibrium conditions and have to be studied prior to modelling the overall effects of pollutants on the water body and aquatic ecosystems. With respect to handling and remediation of contaminated river sediments, either in-place or excavated, a chemical and biological characterization of the material, of the (disposal) site and of the long-term processes is crucial. Passive techniques (e.g. in situ stabilization, subaqueous capping) provide economic advantages as there are no operation costs following their installation. However, the success of these ecological and geochemical engineering approaches is mainly based on an in-depth knowledge of the underlying processes. [source] Combination of Fragmental and Topological Descriptors for QSPR Estimations of Boiling TemperatureMOLECULAR INFORMATICS, Issue 8 2004Irina Abstract The novel QSPR equation for estimation of physicochemical properties of organic substances is proposed. This equation includes contributions depending on the counts of bonds and nonadditive contribution. The nonadditive term is represented as an explicit function of topological distances on the line graph of molecules. The original mathematical form for description of nonadditive contribution is suggested. The application of the derived equation to estimation of normal boiling temperatures for the saturated hydrocarbons (total number of compounds n=198; correlation coefficient r=0.9966; mean square deviation ,=3.4,K) has proved the effectiveness of the proposed approach. The modification of correlation equation is made for estimations of normal boiling temperatures for substances with OH and NH2 groups (n =139; r=0.9971; ,=3.9,K). [source] The glucose and nitrogen starvation response of Bacillus licheniformisPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 3 2007Birgit Voigt Abstract The glucose and nitrogen starvation stimulons of Bacillus licheniformis were determined by transcriptome and proteome analyses. Under both starvation conditions, the main response of B. licheniformis was a switch to the usage of alternative nutrient sources. This was indicated by an induction of genes involved in the metabolism of C-2 substrates during glucose limitation. In addition, B. licheniformis seems to be using other organic substances like amino acids and lipids as carbon sources when subjected to glucose starvation. This observation is supported by the induction of a high number of genes coding for proteins involved in amino acid and lipid degradation. During nitrogen starvation, genes for several proteases and peptidases involved in nitrate and nitrite assimilation were induced, which enables this bacterium to recruit nitrogen from alternative sources. Both starvation conditions led to a down-regulation of transcription of most vegetative genes, which was subsequently reflected by a reduced synthesis of the corresponding proteins. A selected set of genes was induced by both starvation conditions. Among them were yvyD, citA and the putative methylcitrate shunt genes mmgD, mmgE and yqiQ. However, both starvation conditions did not induce a general SigmaB-dependent stress response. [source] Proteins of calcified endoskeleton: II Partial amino acid sequences of endoskeletal proteins and the characterization of proteinaceous organic matrix of spicules from the alcyonarian, Synularia polydactylaPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 4 2005M. Azizur Rahman Abstract Calcified organic substances in the skeleton contain a protein-polysaccharide complex taking a key role in the regulation of bio-calcification. However, information concerning the matrix proteins in alcyonarian and their effect on calcification process is still unknown. For this reason, we have studied the organic matrix of endoskeletal spicules from the alcyonarian coral, Synularia polydactyla, to analyze the proteins with their sequences and investigate the functional properties by a molecular approach. The separated spicules from the colony were identified by scanning electron microscope (SEM). The soluble organic matrix comprised 0.04% of spicule weight. By recording decline of pH in the experimental design, the inhibitory effect of the matrix on CaCO3 precipitation was revealed. Prior to electrophoresis, our analysis of proteins extracted from the soluble organic matrix of the spicules revealed an abundance of proteins in molecular weight. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the preparations showed seven bands of proteins with an apparent molecular mass of 109, 83, 70, 63, 41, 30 and 22 kDa. The proteins were electrophoresed on Tricine-SDS-PAGE after electro-elution treatment, and then transferred to polyvinylidene difluoride (PVDF) membranes and their N -termini were sequenced. Two bands of proteins of about 70 and 63 kDa successfully underwent N -terminal amino acid sequencing. For the detection of calcium binding proteins, a Ca2+ overlay analysis was conducted on the extract by 45Ca autoradiography. The 109 and 63 kDa calcium binding proteins were found to be radioactive. Periodic acid schiff staining indicated that 83 and 63 kDa proteins were glycosylated. An assay for carbonic anhydrase, which is thought to play an important role in the process of calcification revealed low level of the activity. These findings suggest that the endoskeletal spicules of alcyonarian corals have protein-rich organic matrices, which might be related to the calcification process. [source] Investigation by solid-phase microextraction and gas chromatography/mass spectrometry of secondary metabolites in lichens deposited on stone monumentsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2003Francesco De Angelis Lichens are ubiquitous organisms formed by symbiotic associations of fungal hyphas and algae that also grow under often extreme environmental conditions. They produce secondary metabolites, the so-called lichen substances, whose structural characterization can give an important contribution to lichen taxonomy. Lichens are also widely employed as biomonitors of atmospheric pollution; being epiphyte organisms they tend, in fact, to accumulate exogenous compounds. Moreover, it could be questioned if the environmental stress alters their secondary metabolites production. Therefore, a new strategy for the analysis of the organic substances absorbed or metabolized by lichens has been developed. This method exploits the dry solid-phase microextraction (SPME) headspace technique coupled with gas chromatography/mass spectrometry (GC/MS). Lichens coating the stone surfaces of monuments, located in small towns between high mountains and far away from urban environments, have been investigated. In the field of cultural heritage, this study can contribute to the knowledge of the state of conservation of outdoor exposed historical monuments. Copyright © 2003 John Wiley & Sons, Ltd. [source] Lophine derivatives as versatile analytical toolsBIOMEDICAL CHROMATOGRAPHY, Issue 2-3 2003Kenichiro Nakashima Abstract Lophine (2,4,5-triphenylimidazole) derivatives as versatile analytical tools in biomedical sciences are described. Chemiluminescence (CL) and fluorescence (FL) properties of the lophine derivatives are first demonstrated including the CL reaction mechanism, effects of substituents on CL yields, FL spectral behaviors, etc. Next, analytical applications to the determination of metal ions such as cobalt (II) and chromium (VI) are discussed. Finally, the application studies of lophine derivatives as CL and FL reagents for the determination of organic substances in biological materials are presented. Among the derivatives, 2-(4-hydrazinocarbonylphenyl)-4,5-diphenylimidazole (HCPI) and 4-(4,5-diphenyl-1H -imidazol-2-yl)benzoyl chloride (DIB-Cl) are studied, with their excellent properties as labeling reagents for fatty acids and amines and/or phenols, respectively, in high-performance liquid chromatography. The utility of boronic acid derivatives as CL enhancers is also discussed in this review. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||