Shortage in phosphorus （P） resources and P wastewater pollution is considered as a serious problem worldwide. The application of modified biochar for P recovery from wastewater and reuse of recovered P as agricultur...Shortage in phosphorus （P） resources and P wastewater pollution is considered as a serious problem worldwide. The application of modified biochar for P recovery from wastewater and reuse of recovered P as agricultural fertilizer is a preferred process. This work aims to develop a calcium and magnesium loaded biochar （Ca-Mg/biochar） application for P recovery from biogas fermentation liquid. The physico-chemical characterization, adsorption efficiency, adsorption selectivity, and postsorption availability of Ca-Mg/biochar were investigated. The synthesized Ca-Mg/biochar was rich in organic functional groups and in CaO and MgO nanoparticles. With the increase in synthesis temperature, the yield decreased, C content increased, H content decreased, N content remained the same basically, and BET surface area increased. The P adsorption of Ca-Mg/biochar could be accelerated by nano-CaO and nano-MgO particles and reached equilibrium after 360min. The process was endothermic, spontaneous, and showed an increase in the disorder of the solid-liquid interface. Moreover, it could be fitted by the Freundlich model. The maximum P adsorption amounts were 294.22, 315.33, and 326.63 mg/g. The P adsorption selectivity of Ca-Mg/biochar could not be significantly influenced by the typical pH level of biogas fermentation liquid. The nano-CaO and nano-MgO particles of Ca-Mg/biochar could reduce the negative interaction effects of coexisting ions. The P releasing amounts of postsorption Ca-Mg/biochar were in the order of Ca-Mg/B600 〉 Ca-Mg/B4S0 〉 Ca-Mg/B300. Results revealed that postsorption Ca-Mg/biochar can continually release P and is more suitable for an acid environment.展开更多
Phosphorus bioavailability has long been a recurring problem in tropical acid soils. A pot experiment was carried out during three (3) successive rice production cycles at Adiopodoumé to evaluate the response of ...Phosphorus bioavailability has long been a recurring problem in tropical acid soils. A pot experiment was carried out during three (3) successive rice production cycles at Adiopodoumé to evaluate the response of the NERICA 5 rice accession to various doses of calcium, magnesium and phosphorous. The experiment was conducted using a randomized split-plot design. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg·Ca·ha<sup>-1</sup>) and magnesium sulfate (0, 25, 50 and 75 kg·Mg·ha<sup>-1</sup>) and Togo natural phosphate (0, 25, 50 and 75 kg·P·ha<sup>-1</sup>) were determined at each production cycle. The results showed that single-dose natural phosphate supplementation for three cropping cycles resulted in an average enrichment of around 2 mg·P·kg<sup>-1</sup> after each trial following its continuous dissolution, with an increase in DSP (33.31% to 70.52%). The study revealed one strategy for managing and enhancing native P with cations and another for exogenous P: there would be a synergy of Ca/Mg on native P, whereas an antagonism would characterize the two parameters in phosphate fertilization.展开更多
This study is a contribution to improving rice productivity on acidic plateau soils of the tropical rainforest zone. It is based on taking into account the cationic balances of the soil in order to optimize the phosph...This study is a contribution to improving rice productivity on acidic plateau soils of the tropical rainforest zone. It is based on taking into account the cationic balances of the soil in order to optimize the phosphorus (P) nutrition of rice on these acidic soils, where this nutrient constitutes a limiting factor for agricultural production. Three (3) pot trials were conducted in Adiopodoumé in the forested south of Côte d’Ivoire. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg Ca ha<sup>−1</sup>) and magnesium sulfate (0, 25, 50 and 75 kg Mg ha<sup>−1</sup>) were evaluated on the response of NERICA 5 rice at doses 0, 25, 50 and 75 kg P ha<sup>−1</sup> of natural phosphate from Togo, applied only once at the start of the experiment. Additional fertilizers of nitrogen (N) (100 kg N ha<sup>−1</sup>) and potassium (K) (50 kg KCl ha<sup>−1</sup>) were added to each of the tests in a split-plot device. The test results revealed a paddy production potential of approximately 3 to 5 t⋅ha<sup>−1</sup> for NERICA 5 on an acidic soil, under the effect of the interaction of P, Ca and Mg. The quadratic response of rice yield to the doses of these fertilizers would be more dependent on their balance, itself influenced by Ca nutrition. For the sustainability and maintenance of rice production in agro-ecology studied, it was recommended doses of 38 kg Ca ha<sup>−1</sup>, 34 kg Mg ha<sup>−1</sup> in a Ca/Mg ratio (1/1) with intakes of 41 kg P ha<sup>−1</sup>, overall in a ratio 1/1/1 (P/Ca/Mg) more favorable to the availability of free iron considered a guiding element of mineral nutrition. Thus, these promising results should be confirmed in a real environment for better management of the fertilization of rice cultivated on acidic plateau soils in Côte d’Ivoire.展开更多
The combined influence of Mg and Ca treatment on the properties of heat-affected zone (HAZ) of low-carbon steel after high heat input welding was systematically studied. Experimental steels deoxidized with different e...The combined influence of Mg and Ca treatment on the properties of heat-affected zone (HAZ) of low-carbon steel after high heat input welding was systematically studied. Experimental steels deoxidized with different elements were prepared, i.e., C-Mn steel with Al, Ti-Ca steel with Ti and Ca, Ti-Mg-Ca steel with Ti, Mg and Ca. Results showed that the inclusions in C-Mn steel were mainly Al2O3 and MnS with low density and large size. However, the average size was refined to only ~0.34 μm in Ti-Mg-Ca steel and the amount increased remarkably. Microstructure of simulated HAZ for 200 kJ/cm changed from ferrite side plates or upper bainite to acicular ferrite after treatment with Ti, Mg and Ca. Ca addition decreased the strain field around inclusions and enhanced the ability of acicular ferrite nucleation. In situ observation of Ti-Mg-Ca steel showed that the movement of austenite grain boundaries was retarded and nucleation sites of acicular ferrite were greater than Ti-Ca steel because of Mg addition. Impact energy of HAZ at — 40℃ was increased from 7 to 232 J and showed excellent stability because of Ti-Mg-Ca treatment. High volume fraction of acicular ferrite acted as obstacles toward cleavage cracks.展开更多
Hydrochemistry of underground brines along south coast of Laizhou Bay, Shandong, China has been analyzed. Brine samples were collected from 43 wells in this area. It was considered that the brines were originated from...Hydrochemistry of underground brines along south coast of Laizhou Bay, Shandong, China has been analyzed. Brine samples were collected from 43 wells in this area. It was considered that the brines were originated from seawater. However, whether they were formed by seawater evaporation or seawater freezing was not fully sure. We created a simple method by plotting Na/Cl vs. seawater concen-tration factor (SCF) and Ca/Mg vs. SCF to determine the brine formation geochemically. Comparison of our results to previous seawater freezing and evaporation experiments indicated that the brines were formed by seawater evaporation. The ratios of HCO3/Cl of some low salinity brines in the study area were relatively higher, indicating that the brines may have mixed with other waters after the generation. The Br/Cl ratios of the brines decreased annually in the past 20 to 30 years of exploitation, indicating down-ward permeation of the brine from which bromine was extracted.展开更多
The usefulness of limestone as an industrial raw material is dependent on the level of its purity, largely controlled by diagenesis and the depositional setting. Limestone samples (83) obtained from the Ewekoro Format...The usefulness of limestone as an industrial raw material is dependent on the level of its purity, largely controlled by diagenesis and the depositional setting. Limestone samples (83) obtained from the Ewekoro Formation exposed in quarry sections at Shagamu were analyzed using X-Ray Fluorescence spectrometry (XRF). A geochemical characterization of result was done to evaluate the purity levels and the implications on provenance, diagenesis, and depositional setting of the limestone. Five limestone beds from quarry sections (15 locations) were logged. Beds “E”, “D”, “C”, “B”, and “A” comprised sandy algal in sparry calcite cement, sandy biomicrite, algal biomicrite, sandy algal biomicrite, and the intra-sparite facies respectively. Results of major elements che- mistry indicated concentrations (in wt%) as follows: CaO (33.71 - 59.99), MgO (0.39 - 3.15), Al<sub>2</sub>O<sub>3</sub> (0.47 - 3.23), Fe<sub>2</sub>O<sub>3</sub> (0.51 - 3.43), SiO<sub>2</sub> (0.47 - 45.98), SO<sub>3</sub> (0.10 - 2.27), K<sub>2</sub>O (0.02 - 0.28), Na<sub>2</sub>O (0.00 - 10.0), TiO<sub>2</sub> (0.00 - 0.27), P<sub>2</sub>O<sub>5</sub> (0.02 - 0.92), MnO (0.01 - 0.06) and Loss on ignition (17.64 - 45.20). Geochemical result showed that the samples are enriched in CaO, while SiO<sub>2</sub> varies widely, likely due to hinterland input. Plots of SiO<sub>2</sub> versus CaO concentrations depicted a negative correlation attributable to chemical diagenetic processes. Diagenesis of the carbonate in form of reversible replacement of SiO<sub>2</sub> with CaO and vice versa occurred under a shallow marine condition. This negative correlation between these oxides (CaO and SiO<sub>2</sub>) dictates zones of high purity limestones that are of desirable industrial applications. Relatively high silica content in the northwestern part is possible indication of outlets to the continental or inland areas where clastic sediment source may have been prominent. Ratios of Ca/Mg and Mg/Ca indicated a relatively low rate of e展开更多
The leaf of Psidium guava is traditionally used in Asia to manage, control and treat diabetes. We designed this study to elucidate the effect of the administration of oral doses of aqueous and ethanol extract from Psi...The leaf of Psidium guava is traditionally used in Asia to manage, control and treat diabetes. We designed this study to elucidate the effect of the administration of oral doses of aqueous and ethanol extract from Psidium guava leaves on plasma glucose, lipid profiles and the sensitivity of the vascular mesenteric bed to Phenylephrine in diabetic and non diabetic rats. Animals were divided into 5 groups (n = 10): two groups served as non-diabetic controls (NDC), while the other groups had diabetes induced with a single injection of streptozotocin (STZ). Psidium guava-treated chronic diabetic (PSG-CD) and Psidium guava-treated controls (PSG-C) received 1g/l of Psidium guavaadded to the drinking water for 8 weeks. The mesenteric vascular beds were prepared using the McGregor method. Administration of Psidium guava caused Ca/Mg ratio, plasma glucose, high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), total cholesterol and triglyceride concentrations to return to normal levels, and was shown to decrease alteration in vascular reactivity to vasoconstrictor agents. Our results support the hypothesis that Psidium guava could play a role in the management of diabetes and the prevention of vascular complications in STZ-induced diabetic rats.展开更多
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120008120013)the National Natural Science Foundation of China (No. 31401944)+2 种基金the Beijing Natural Science Foundation (No. 6144026)the China Scholarship Council (No. 201206355006)the Chinese Universities Scientific Fund of China Agricultural University (No. 2011JS169)
文摘Shortage in phosphorus （P） resources and P wastewater pollution is considered as a serious problem worldwide. The application of modified biochar for P recovery from wastewater and reuse of recovered P as agricultural fertilizer is a preferred process. This work aims to develop a calcium and magnesium loaded biochar （Ca-Mg/biochar） application for P recovery from biogas fermentation liquid. The physico-chemical characterization, adsorption efficiency, adsorption selectivity, and postsorption availability of Ca-Mg/biochar were investigated. The synthesized Ca-Mg/biochar was rich in organic functional groups and in CaO and MgO nanoparticles. With the increase in synthesis temperature, the yield decreased, C content increased, H content decreased, N content remained the same basically, and BET surface area increased. The P adsorption of Ca-Mg/biochar could be accelerated by nano-CaO and nano-MgO particles and reached equilibrium after 360min. The process was endothermic, spontaneous, and showed an increase in the disorder of the solid-liquid interface. Moreover, it could be fitted by the Freundlich model. The maximum P adsorption amounts were 294.22, 315.33, and 326.63 mg/g. The P adsorption selectivity of Ca-Mg/biochar could not be significantly influenced by the typical pH level of biogas fermentation liquid. The nano-CaO and nano-MgO particles of Ca-Mg/biochar could reduce the negative interaction effects of coexisting ions. The P releasing amounts of postsorption Ca-Mg/biochar were in the order of Ca-Mg/B600 〉 Ca-Mg/B4S0 〉 Ca-Mg/B300. Results revealed that postsorption Ca-Mg/biochar can continually release P and is more suitable for an acid environment.
文摘Phosphorus bioavailability has long been a recurring problem in tropical acid soils. A pot experiment was carried out during three (3) successive rice production cycles at Adiopodoumé to evaluate the response of the NERICA 5 rice accession to various doses of calcium, magnesium and phosphorous. The experiment was conducted using a randomized split-plot design. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg·Ca·ha<sup>-1</sup>) and magnesium sulfate (0, 25, 50 and 75 kg·Mg·ha<sup>-1</sup>) and Togo natural phosphate (0, 25, 50 and 75 kg·P·ha<sup>-1</sup>) were determined at each production cycle. The results showed that single-dose natural phosphate supplementation for three cropping cycles resulted in an average enrichment of around 2 mg·P·kg<sup>-1</sup> after each trial following its continuous dissolution, with an increase in DSP (33.31% to 70.52%). The study revealed one strategy for managing and enhancing native P with cations and another for exogenous P: there would be a synergy of Ca/Mg on native P, whereas an antagonism would characterize the two parameters in phosphate fertilization.
文摘This study is a contribution to improving rice productivity on acidic plateau soils of the tropical rainforest zone. It is based on taking into account the cationic balances of the soil in order to optimize the phosphorus (P) nutrition of rice on these acidic soils, where this nutrient constitutes a limiting factor for agricultural production. Three (3) pot trials were conducted in Adiopodoumé in the forested south of Côte d’Ivoire. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg Ca ha<sup>−1</sup>) and magnesium sulfate (0, 25, 50 and 75 kg Mg ha<sup>−1</sup>) were evaluated on the response of NERICA 5 rice at doses 0, 25, 50 and 75 kg P ha<sup>−1</sup> of natural phosphate from Togo, applied only once at the start of the experiment. Additional fertilizers of nitrogen (N) (100 kg N ha<sup>−1</sup>) and potassium (K) (50 kg KCl ha<sup>−1</sup>) were added to each of the tests in a split-plot device. The test results revealed a paddy production potential of approximately 3 to 5 t⋅ha<sup>−1</sup> for NERICA 5 on an acidic soil, under the effect of the interaction of P, Ca and Mg. The quadratic response of rice yield to the doses of these fertilizers would be more dependent on their balance, itself influenced by Ca nutrition. For the sustainability and maintenance of rice production in agro-ecology studied, it was recommended doses of 38 kg Ca ha<sup>−1</sup>, 34 kg Mg ha<sup>−1</sup> in a Ca/Mg ratio (1/1) with intakes of 41 kg P ha<sup>−1</sup>, overall in a ratio 1/1/1 (P/Ca/Mg) more favorable to the availability of free iron considered a guiding element of mineral nutrition. Thus, these promising results should be confirmed in a real environment for better management of the fertilization of rice cultivated on acidic plateau soils in Côte d’Ivoire.
文摘The combined influence of Mg and Ca treatment on the properties of heat-affected zone (HAZ) of low-carbon steel after high heat input welding was systematically studied. Experimental steels deoxidized with different elements were prepared, i.e., C-Mn steel with Al, Ti-Ca steel with Ti and Ca, Ti-Mg-Ca steel with Ti, Mg and Ca. Results showed that the inclusions in C-Mn steel were mainly Al2O3 and MnS with low density and large size. However, the average size was refined to only ~0.34 μm in Ti-Mg-Ca steel and the amount increased remarkably. Microstructure of simulated HAZ for 200 kJ/cm changed from ferrite side plates or upper bainite to acicular ferrite after treatment with Ti, Mg and Ca. Ca addition decreased the strain field around inclusions and enhanced the ability of acicular ferrite nucleation. In situ observation of Ti-Mg-Ca steel showed that the movement of austenite grain boundaries was retarded and nucleation sites of acicular ferrite were greater than Ti-Ca steel because of Mg addition. Impact energy of HAZ at — 40℃ was increased from 7 to 232 J and showed excellent stability because of Ti-Mg-Ca treatment. High volume fraction of acicular ferrite acted as obstacles toward cleavage cracks.
基金Supported by NSFC (No. 40276026), and the Key Science and Tech-nology Plan of The Ministry of Education of China ([2000]156-00079)
文摘Hydrochemistry of underground brines along south coast of Laizhou Bay, Shandong, China has been analyzed. Brine samples were collected from 43 wells in this area. It was considered that the brines were originated from seawater. However, whether they were formed by seawater evaporation or seawater freezing was not fully sure. We created a simple method by plotting Na/Cl vs. seawater concen-tration factor (SCF) and Ca/Mg vs. SCF to determine the brine formation geochemically. Comparison of our results to previous seawater freezing and evaporation experiments indicated that the brines were formed by seawater evaporation. The ratios of HCO3/Cl of some low salinity brines in the study area were relatively higher, indicating that the brines may have mixed with other waters after the generation. The Br/Cl ratios of the brines decreased annually in the past 20 to 30 years of exploitation, indicating down-ward permeation of the brine from which bromine was extracted.
文摘The usefulness of limestone as an industrial raw material is dependent on the level of its purity, largely controlled by diagenesis and the depositional setting. Limestone samples (83) obtained from the Ewekoro Formation exposed in quarry sections at Shagamu were analyzed using X-Ray Fluorescence spectrometry (XRF). A geochemical characterization of result was done to evaluate the purity levels and the implications on provenance, diagenesis, and depositional setting of the limestone. Five limestone beds from quarry sections (15 locations) were logged. Beds “E”, “D”, “C”, “B”, and “A” comprised sandy algal in sparry calcite cement, sandy biomicrite, algal biomicrite, sandy algal biomicrite, and the intra-sparite facies respectively. Results of major elements che- mistry indicated concentrations (in wt%) as follows: CaO (33.71 - 59.99), MgO (0.39 - 3.15), Al<sub>2</sub>O<sub>3</sub> (0.47 - 3.23), Fe<sub>2</sub>O<sub>3</sub> (0.51 - 3.43), SiO<sub>2</sub> (0.47 - 45.98), SO<sub>3</sub> (0.10 - 2.27), K<sub>2</sub>O (0.02 - 0.28), Na<sub>2</sub>O (0.00 - 10.0), TiO<sub>2</sub> (0.00 - 0.27), P<sub>2</sub>O<sub>5</sub> (0.02 - 0.92), MnO (0.01 - 0.06) and Loss on ignition (17.64 - 45.20). Geochemical result showed that the samples are enriched in CaO, while SiO<sub>2</sub> varies widely, likely due to hinterland input. Plots of SiO<sub>2</sub> versus CaO concentrations depicted a negative correlation attributable to chemical diagenetic processes. Diagenesis of the carbonate in form of reversible replacement of SiO<sub>2</sub> with CaO and vice versa occurred under a shallow marine condition. This negative correlation between these oxides (CaO and SiO<sub>2</sub>) dictates zones of high purity limestones that are of desirable industrial applications. Relatively high silica content in the northwestern part is possible indication of outlets to the continental or inland areas where clastic sediment source may have been prominent. Ratios of Ca/Mg and Mg/Ca indicated a relatively low rate of e
文摘The leaf of Psidium guava is traditionally used in Asia to manage, control and treat diabetes. We designed this study to elucidate the effect of the administration of oral doses of aqueous and ethanol extract from Psidium guava leaves on plasma glucose, lipid profiles and the sensitivity of the vascular mesenteric bed to Phenylephrine in diabetic and non diabetic rats. Animals were divided into 5 groups (n = 10): two groups served as non-diabetic controls (NDC), while the other groups had diabetes induced with a single injection of streptozotocin (STZ). Psidium guava-treated chronic diabetic (PSG-CD) and Psidium guava-treated controls (PSG-C) received 1g/l of Psidium guavaadded to the drinking water for 8 weeks. The mesenteric vascular beds were prepared using the McGregor method. Administration of Psidium guava caused Ca/Mg ratio, plasma glucose, high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), total cholesterol and triglyceride concentrations to return to normal levels, and was shown to decrease alteration in vascular reactivity to vasoconstrictor agents. Our results support the hypothesis that Psidium guava could play a role in the management of diabetes and the prevention of vascular complications in STZ-induced diabetic rats.
