The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Wolfgang Maret - One of the best experts on this subject based on the ideXlab platform.
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Zinc-Buffering Capacity of a eukaryotic cell at physiological pZn
JBIC Journal of Biological Inorganic Chemistry, 2006Co-Authors: Artur Krężel, Wolfgang MaretAbstract:In spite of the paramount importance of zinc in biology, dynamic aspects of cellular zinc metabolism remain poorly defined at the molecular level. Investigations with human colon cancer (HT-29) cells establish a total cellular zinc concentration of 264 μM. Remarkably, about 10% of the potential high-affinity zinc-binding sites are not occupied by zinc, resulting in a surplus of 28 μM ligands (average K _d ^c = 83 pM) that ascertain cellular zinc-Buffering Capacity and maintain the “free” zinc concentration in proliferating cells at picomolar levels (784 pM, pZn = 9.1). This zinc-Buffering Capacity allows zinc to fluctuate only with relatively small amplitudes (ΔpZn = 0.3; below 1 nM) without significantly perturbing physiological pZn. Thus, the “free” zinc concentrations in resting and differentiated HT-29 cells are 614 pM and 1.25 nM, respectively. The calculation of these “free” zinc concentrations is based on measurements at different concentrations of the fluorogenic zinc-chelating agent and extrapolation to a zero concentration of the agent. It depends on the state of the cell, its Buffering Capacity, and the zinc dissociation constant of the chelating agent. Zinc induction of thionein (apometallothionein) ensures a surplus of unbound ligands, increases zinc-Buffering Capacity and the availability of zinc (ΔpZn = 0.8), but preserves the zinc-Buffering Capacity of the unoccupied high-affinity zinc-binding sites, perhaps for crucial physiological functions. Jointly, metallothionein and thionein function as the major zinc buffer under conditions of increased cellular zinc.
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zinc Buffering Capacity of a eukaryotic cell at physiological pzn
Journal of Biological Inorganic Chemistry, 2006Co-Authors: Artur Krezel, Wolfgang MaretAbstract:In spite of the paramount importance of zinc in biology, dynamic aspects of cellular zinc metabolism remain poorly defined at the molecular level. Investigations with human colon cancer (HT-29) cells establish a total cellular zinc concentration of 264 microM. Remarkably, about 10% of the potential high-affinity zinc-binding sites are not occupied by zinc, resulting in a surplus of 28 muM ligands (average Kd(c) = 83 pM) that ascertain cellular zinc-Buffering Capacity and maintain the "free" zinc concentration in proliferating cells at picomolar levels (784 pM, pZn = 9.1). This zinc-Buffering Capacity allows zinc to fluctuate only with relatively small amplitudes (DeltapZn = 0.3; below 1 nM) without significantly perturbing physiological pZn. Thus, the "free" zinc concentrations in resting and differentiated HT-29 cells are 614 pM and 1.25 nM, respectively. The calculation of these "free" zinc concentrations is based on measurements at different concentrations of the fluorogenic zinc-chelating agent and extrapolation to a zero concentration of the agent. It depends on the state of the cell, its Buffering Capacity, and the zinc dissociation constant of the chelating agent. Zinc induction of thionein (apometallothionein) ensures a surplus of unbound ligands, increases zinc-Buffering Capacity and the availability of zinc (DeltapZn = 0.8), but preserves the zinc-Buffering Capacity of the unoccupied high-affinity zinc-binding sites, perhaps for crucial physiological functions. Jointly, metallothionein and thionein function as the major zinc buffer under conditions of increased cellular zinc.
Jun Jiang - One of the best experts on this subject based on the ideXlab platform.
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mechanisms for increasing the ph Buffering Capacity of an acidic ultisol by crop residue derived biochars
Journal of Agricultural and Food Chemistry, 2017Co-Authors: Renyong Shi, Jun Jiang, Zhineng Hong, Abdulahaal M Baquy, Wei QianAbstract:The effects and underlying mechanisms of crop residue-derived biochars on the pH Buffering Capacity (pHbuff) of an acidic Ultisol, with low pHbuff, were investigated through indoor incubation and simulated acidification experiments. The incorporation of biochars significantly increased soil pHbuff with the magnitude of the increase dependent on acid Buffering Capacity of the biochar incorporated to the soil. Cation release, resulting from the protonation of carboxyl groups on biochar surfaces and the dissolution of carbonates, was the predominant mechanism responsible for the increase in soil pHbuff at pH 4.0–7.0 and accounted for >67% of the increased pHbuff. The reaction of protons with soluble silica (Si) in biochars derived from rice straw and corn stover also accounted for ∼20% of the pHbuff increase due to H3SiO4– precipitation. In conclusion, the incorporation of crop residue-derived biochars into acidic soils increased soil pHbuff with peanut stover biochar being the most effective biochar tested.
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pH Buffering Capacity of acid soils from tropical and subtropical regions of China as influenced by incorporation of crop straw biochars
Journal of Soils and Sediments, 2012Co-Authors: An-zhen Zhao, Jin-hua Yuan, Jun JiangAbstract:Purpose The key factors influencing pH Buffering Capacity of acid soils from tropical and subtropical regions, and effects of soil evolution and incorporation of biochars on pH Buffering Capacity were investigated to develop suitable methods to increase pH Buffering Capacity of acid soils.
Fortunata Lombardi - One of the best experts on this subject based on the ideXlab platform.
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characterisation of major component leaching and Buffering Capacity of rdf incineration and gasification bottom ash in relation to reuse or disposal scenarios
Waste Management, 2012Co-Authors: S Rocca, Andre Van Zomeren, J J Dijkstra, Rob N. J. Comans, G Costa, Fortunata LombardiAbstract:Thermal treatment of refuse derived fuel (RDF) in waste-to-energy (WtE) plants is considered a promising solution to reduce waste volumes for disposal, while improving material and energy recovery from waste. Incineration is commonly applied for the energetic valorisation of RDF, although RDF gasification has also gained acceptance in recent years. In this study we focused on the environmental properties of bottom ash (BA) from an RDF incineration (RDF-I, operating temperature 850-1000 degrees C) and a RDF gasification plant (RDF-G, operating temperature 1200-1400 degrees C), by evaluating the total composition, mineralogy, Buffering Capacity, leaching behaviour (both at the material's own pH and as a function of pH) of both types of slag. In addition, Buffering Capacity results and pH-dependence leaching concentrations of major components obtained for both types of BA were analysed by geochemical modelling. Experimental results showed that the total content of major components for the two types of BA was fairly similar and possibly related to the characteristics of the RDF feedstock. However, significant differences in the contents of trace metals and salts were observed for the two BA samples as a result of the different operating conditions (i.e. temperature) adopted by the two RDF thermal treatment plants. Mineralogy analysis showed in fact that the RDF-I slag consisted of an assemblage of several crystalline phases while the RDF-G slag was mainly made up by amorphous glassy phases. The leached concentrations of major components (e.g. Ca, Si) at the natural pH of each type of slag did not reflect their total contents as a result of the partial solubility of the minerals in which these components were chemically bound. In addition, comparison of total contents with leached concentrations of minor elements (e.g. Pb, Cu) showed no obvious relationship for the two types of BA. According to the compliance leaching test results, the RDF-G BA would meet the limits of the Italian legislation for reuse and the European acceptance criteria for inert waste landfilling. RDF-I BA instead would meet the European acceptance criteria for non hazardous waste landfilling. A new geochemical modelling approach was followed in order to predict the leaching behaviour of major components and the pH Buffering Capacity of the two types of slags on the basis of independent mineralogical information obtained by XRD analysis and the bulk composition of the slag. It was found that the combined use of data regarding the mineralogical characterization and the Buffering Capacity of the slag material can provide an independent estimate of both the identity and the amount of minerals that contribute to the leaching process. This new modelling approach suggests that only a limited amount of the mineral phases that control the pH, Buffering Capacity and major component leaching from the solid samples is available for leaching, at least on the time scale of the applied standard leaching tests. As such, the presented approach can contribute to gain insights for the identification of the types and amounts of minerals that control the leaching properties and pH Buffering Capacity of solid residues such as RDF incineration and gasification bottom ash.
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characterisation of major component leaching and Buffering Capacity of rdf incineration and gasification bottom ash in relation to reuse or disposal scenarios
Waste Management, 2012Co-Authors: S Rocca, Andre Van Zomeren, J J Dijkstra, Rob N. J. Comans, G Costa, Fortunata LombardiAbstract:Thermal treatment of refuse derived fuel (RDF) in waste-to-energy (WtE) plants is considered a promising solution to reduce waste volumes for disposal, while improving material and energy recovery from waste. Incineration is commonly applied for the energetic valorisation of RDF, although RDF gasification has also gained acceptance in recent years. In this study we focused on the environmental properties of bottom ash (BA) from an RDF incineration (RDF-I, operating temperature 850-1000 degrees C) and a RDF gasification plant (RDF-G, operating temperature 1200-1400 degrees C), by evaluating the total composition, mineralogy, Buffering Capacity, leaching behaviour (both at the material's own pH and as a function of pH) of both types of slag. In addition, Buffering Capacity results and pH-dependence leaching concentrations of major components obtained for both types of BA were analysed by geochemical modelling. Experimental results showed that the total content of major components for the two types of BA was fairly similar and possibly related to the characteristics of the RDF feedstock. However, significant differences in the contents of trace metals and salts were observed for the two BA samples as a result of the different operating conditions (i.e. temperature) adopted by the two RDF thermal treatment plants. Mineralogy analysis showed in fact that the RDF-I slag consisted of an assemblage of several crystalline phases while the RDF-G slag was mainly made up by amorphous glassy phases. The leached concentrations of major components (e.g. Ca, Si) at the natural pH of each type of slag did not reflect their total contents as a result of the partial solubility of the minerals in which these components were chemically bound. In addition, comparison of total contents with leached concentrations of minor elements (e.g. Pb, Cu) showed no obvious relationship for the two types of BA. According to the compliance leaching test results, the RDF-G BA would meet the limits of the Italian legislation for reuse and the European acceptance criteria for inert waste landfilling. RDF-I BA instead would meet the European acceptance criteria for non hazardous waste landfilling. A new geochemical modelling approach was followed in order to predict the leaching behaviour of major components and the pH Buffering Capacity of the two types of slags on the basis of independent mineralogical information obtained by XRD analysis and the bulk composition of the slag. It was found that the combined use of data regarding the mineralogical characterization and the Buffering Capacity of the slag material can provide an independent estimate of both the identity and the amount of minerals that contribute to the leaching process. This new modelling approach suggests that only a limited amount of the mineral phases that control the pH, Buffering Capacity and major component leaching from the solid samples is available for leaching, at least on the time scale of the applied standard leaching tests. As such, the presented approach can contribute to gain insights for the identification of the types and amounts of minerals that control the leaching properties and pH Buffering Capacity of solid residues such as RDF incineration and gasification bottom ash.
Hao Wu - One of the best experts on this subject based on the ideXlab platform.
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effect of ph Buffering Capacity and sources of dietary sulfur on rumen fermentation sulfide production methane production sulfate reducing bacteria and total archaea in in vitro rumen cultures
Bioresource Technology, 2015Co-Authors: Hao Wu, Qingxiang Meng, Zhongtang YuAbstract:Abstract The effects of three types of dietary sulfur on in vitro fermentation characteristics, sulfide production, methane production, and microbial populations at two different buffer capacities were examined using in vitro rumen cultures. Addition of dry distilled grain with soluble (DDGS) generally decreased total gas production, degradation of dry matter and neutral detergent fiber, and concentration of total volatile fatty acids, while increasing ammonia concentration. High Buffering Capacity alleviated these adverse effects on fermentation. Increased sulfur content resulted in decreased methane emission, but total Archaea population was not changed significantly. The population of sulfate reducing bacteria was increased in a sulfur type-dependent manner. These results suggest that types of dietary sulfur and Buffering Capacity can affect rumen fermentation and sulfide production. Diet Buffering Capacity, and probably alkalinity, may be increased to alleviate some of the adverse effects associated with feeding DDGS at high levels.
Xu Xinwu - One of the best experts on this subject based on the ideXlab platform.
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Study on acid-alkali Buffering Capacity of the castor stalks.
Journal of Nanjing Forestry University, 2009Co-Authors: Li Xiaoping, Zhou Ding-guo, Xu Zhongxiang, Han Shuguang, Xu XinwuAbstract:To establish a better manufacture craftwork for making castor stalks based board,the pH and acid-alkali Buffering Capacity of the castor stalks and its different parts were examined.Besides,the relationship among pH,acid alkali Buffering Capacity and the extracts content,ash content was analyzed with SAS software.The results showed that the pH and the Buffering Capacity of the castor oil plant and its different parts were different.There was some relation between them and the extracts content and ash content.Furthermore the pH and the Buffering Capacity changed with the extracts and ash content changed.The pH of the castor oil plant was(5.26±0.01),acidity,the acid Buffering Capacity was(19.5±1) and the alkali Buffering Capacity was(48.5±1) of the stalks.So their acid alkali character was near to the character of the wood and it was feasible to make castor stalks based with urea-formaldehyde resin.
