The complex [Fe(C14H14NO2)3]2H2O has been prepared by reaction of N-p-methylphenyl-3-hydroxy-2-ethyl-4-pyridinone with FeCl36H2O. A single-crystal X-ray study shows that the iron atoms lie in a trigonally distorted oc...The complex [Fe(C14H14NO2)3]2H2O has been prepared by reaction of N-p-methylphenyl-3-hydroxy-2-ethyl-4-pyridinone with FeCl36H2O. A single-crystal X-ray study shows that the iron atoms lie in a trigonally distorted octahedral environment coordinated to the hydroxy and ketone oxygen atoms of three ligands in the mer configuration Mr=773.57(C42H46N3O8Fe). The crystal is hexagonal with space group P31c; a=15.943(2), c=17.612(4)? V=3877.0(12)?, Z=4, Dc=1.325g/cm3, m=0.445mm-1, F(000)=1634, R=0.0446, wR= 0.1154 for 3085 reflections with I >2s(I). The bond lengths from iron to oxygens are 1.980(1)?for the ketone oxygens and 2.071(1)?for the hydroxy oxygens. The molecule exhibits the expected propeller shape, and the angle of the trigonal twist is 48.37. The dihedral angles are 0.5(2)?between chelate ring plane and pyridine ring plane and 71.31(7)?between pyridine ring plane and benzene ring plane. The solvent H2O(O(3) and O(4)) molecules are linked with O(2) and O(1) by hydrogen bonds with bond lengths 2.900(1) and 2.999(1)? respectively.展开更多
A comparative thermal decomposition kinetic investigation on Fe(III) complexes of a antipyrine Schiff base ligand, 1,2-Bis(imino-4’-antipyrinyl)ethane (GA)), with varying counter anions viz. CIO4-, NO3-, SCN-, Cl-, a...A comparative thermal decomposition kinetic investigation on Fe(III) complexes of a antipyrine Schiff base ligand, 1,2-Bis(imino-4’-antipyrinyl)ethane (GA)), with varying counter anions viz. CIO4-, NO3-, SCN-, Cl-, and Br-, has been done by thermogravimetric analysis by using Coats-Redfern equation. The kinetic parameters like activation energy (E), pre-exponential factor (A) and entropy of activation (ΔS) were quantified. On comparing the various kinetic parameters, lower activation energy was observed in second stage as compared to first thermal decomposition stage. The same trend has been observed for pre-exponential factor (A) and entropy of activation (ΔS). The present results show that the starting materials having higher activation energy (E), are more stable than the intermediate products, however;the intermediate products possess well-ordered chemical structure due to their highly negative entropy of activation (ΔS) values. The present investigation proves that the counter anions play an important role on the thermal decomposition kinetics of the complexes.展开更多
It has previously been demonstrated that phenanthroline-based ligands used to make gold metallotherapuetics have the ability to exhibit cytotoxicity when not coordinated to the metal center. In an effort to help asses...It has previously been demonstrated that phenanthroline-based ligands used to make gold metallotherapuetics have the ability to exhibit cytotoxicity when not coordinated to the metal center. In an effort to help assess the mechanism by which these ligands may cause tumor cell death, iron binding and removal experiments have been considered. The close linkage between cell proliferation and intracellular iron concentrations suggest that iron deprivation strategies may be a mechanism involved in inhibiting tumor cell growth. With the creation of iron (III) phen complexes, the iron binding abilities of three polypyridal ligands [1,10-phenanthroline (phen), 2,9-dimethyl-1, 10-phenanthroline (methylphen), and 2,9-di-sec-butyl-1, 10-phenanthroline (sec-butylphen)] can be tested via a competition reaction with a known iron chelator. Therefore, iron (III) complexes possessing all three ligands were synthesized. Initial mass spectrometric and infrared absorption data indicate that iron (III) tetrachloride complex ions with protonated phen ligands (RphenH+) were formed: [phenH][FeCl4], [methylphenH][FeCl4], [sec-butylphenH][FeCl4]. UV-vis spectroscopy was used to monitor the stability of the complex ions, and it was found that the sec-butylpheniron complex was more stable than the phen and methylphen analogues. This was based on the observation that free ligand was observed immediately upon the addition of EDTA to the [phenH][FeCl4] and [methylphenH] [FeCl4] complex ions.展开更多
Background: Iron deficiency anemia in infants is the most common micronutrient deficiency worldwide. The main cause is low iron intake in the presence of accelerated physiologic growth rate. Objective: The current stu...Background: Iron deficiency anemia in infants is the most common micronutrient deficiency worldwide. The main cause is low iron intake in the presence of accelerated physiologic growth rate. Objective: The current study aimed at prospectively comparing the efficacy of iron III hydroxide polymaltose syrup (IPS) versus iron III hydroxide polymaltose drops (IPD) in treating iron deficiency among infants attending the hematology outpatient clinic. Our hypothesis was that IPS would be less effective possibly related to the difficulty of giving the medication. Methods: Participants diagnosed with iron deficiency anemia between 11-24 months were randomly assigned to receive either IPS or IPD for 3 months. The main outcome parameter was hemoglobin blood level, while the secondary outcome parameters were: 1) iron;2) ferritin;3) transferrin (i.e.?total iron binding capacity);4) mean corpuscular volume;and 5) red blood cell distribution width. Results: Out of the 104 recruited infants, 55 (52%) completed the study: 29 in the IPS group and26 inthe IPD group. There was no significant difference in the main outcome parameter at either 1 or 3 months of treatment: mean hemoglobin was 10.5 versus 10.7 g/dL within a 1 month treatment, P = 0.4;mean hemoglobin was 11.0 versus 11.1 g/dL within a 3 months of treatment, P = 0.59. Likewise, no significant differences were found with respect to the occurrence of side effects. Conclusion: Oral IPD and IPS are equally effective in treating iron deficiency anemia in infants aged 11 - 24 months.展开更多
Hydrotalcite-type anionic clays are a group of important materials used in adsorption processes, mainly for organic pollutants removal due the layered double hydroxide structure. The layer-interlayer interactions prov...Hydrotalcite-type anionic clays are a group of important materials used in adsorption processes, mainly for organic pollutants removal due the layered double hydroxide structure. The layer-interlayer interactions provide a structural memory even after dehydration and dehydroxylation process, since a very stable interlayer anions are part of material composition, like the carbonate one. A limited numbers of trivalent modifier cations can replace the aluminium cation due the ionic radii mismatch or oxidation state restrictions. Transition metal cations can replace the aluminium one in octahedral site of hydroxide lamellas in order to improve the adsorptive behaviors. In this work, we have investigate three compositions of carbonated magnesium-aluminium hydrotalcite with dif-ferent iron (III) contents through the co-precipitation method at pH 11 and aging step at 60°C for 6 hours. Thermal analysis was performed aiming the determination of the hydration water and hydroxyl amounts in dried precipitate samples, taking in account the results obtained for X-ray diffractometry, infrared spectroscopy, and nitrogen adsorption-desorption characterization for several thermally treated samples. All of synthesized samples showed high surface areas, even for high temperature of thermal treatment. The co-substitution with iron (III) reduced the temperature of dehydration and dehydroxylation process, but the co-substitution at 5 mol% provides other desirables characteristics, like a more amount of rhombohedral HDL phase and higher porosity, even after the thermal treatment at 500°C for 4 hours. This result makes that composition very applicable as a reusable adsorbent material in order to removal several types of micro-pollutant compounds in aqueous media.展开更多
As a common precursor for supercritical CO_(2)(scCO_(2))deposition techniques,solubility data of organometallic complexes in scCO_(2)is crucial for the preparation of nanocomposites.Recently,metal acetylacetonates hav...As a common precursor for supercritical CO_(2)(scCO_(2))deposition techniques,solubility data of organometallic complexes in scCO_(2)is crucial for the preparation of nanocomposites.Recently,metal acetylacetonates have shown great potential for the preparation of single-atom catalytic materials.In this study,the solubilities of iron(Ⅲ)acetylacetonate(Fe(acac)3)and nickel(Ⅱ)acetylacetonate(Ni(acac)2)were measured at the temperature from 313.15 to 333.15 K and in the pressure range of 9.5–25.2 MPa to accumulate new solubility data.Solubility was measured using a static weight loss method.The semi-empirical models proposed by Chrastil and Sung et al.were used to correlate the solubility data of Fe(acac)3 and Ni(acac)2.The equations obtained can be used to predict the solubility of the same system in the experimental range.展开更多
A new kinetic spectrophotometric method for the determinations of iron(III) has been developed based on its catalytic effects on the oxidation reactions of azocarmine B by KIO4.Under the optimum conditions,the linea...A new kinetic spectrophotometric method for the determinations of iron(III) has been developed based on its catalytic effects on the oxidation reactions of azocarmine B by KIO4.Under the optimum conditions,the linear range for the determination of Fe3+ by the proposed method is 0～08μg/25ml,and the detection limit is 695×10-10g/ml.The relative standard deviation for 11 replicate determinations of 04 μg Fe(III) is 15%.The results obtained from the studies on the effects by more than 30 kinds of foreign ions indicated that the method free from most interference.The method has been applied for the determination of iron in water,human hair and food samples with relative standard deviations between 08% and 34%,and the recovery between 96% and 104%.展开更多
This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsena...This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsenate varies from 0.5 to 200 mg/l. A kinetic model was considered to describe the arsenates sorption on ZVI material. The kinetics of the arsenate sorption processes were described by the Langmuir kinetic model. The sorption capacity increases with high initial concentration which obtained the maximum sorption 2.1 mg/g at 200 mg/l of arsenate initial concentration. The results show that the rapid initial sorption rates of arsenate were occurred at the beginning of experiments running time, followed by a slower removal that gradually approaches an equilibrium condition. The data from laboratory batch experiments were used to verify the simulation results of the kinetic model resulting in good agreement between measured and modeled results. The results indicate that ZVI could be employed as sorbent materials to enhance the sorption processes and increase the removal rate of arsenate from water.展开更多
Aerobic rice has the advantage of saving water. Most published work has focused on improving its yield, while few reported on its micronutrient status. In fact, Fe deficiency is a common nutritional problem in the pro...Aerobic rice has the advantage of saving water. Most published work has focused on improving its yield, while few reported on its micronutrient status. In fact, Fe deficiency is a common nutritional problem in the production of aerobic rice. Short- term hydroponic culture experiments were conducted to study the response of aerobic rice to Fe deficiency and the effect of root exudates from Fe-deficient wheat on its Fe uptake ability. The results indicate that the amount of phytosiderophores （PS） released from aerobic rice did not increase under Fe deficient conditions. The Fe（III） reducing capacity of Fe-deficient aerobic rice did not increase and the solution pH did not decrease significantly. What＇s more, no obvious swelling was observed in the root tips. Aerobic rice did not show special responses to improve their Fe nutrition under Fe deficiency as both strategy I and II plants though they were very sensitive to Fe deficiency. This may be a reason which causes Fe deficiency problem in aerobic rice. However, root exudates from Fe-deficient wheat （PSw） could improve its Fe nutrition in the presence of insoluble Fe（OH）3. This suggests that aerobic rice could utilize Fe activated by PSw.展开更多
Iron tetranitrosyl complex bearing the thiosulfate ligand (TNIC) is an efficient nitrogen monoxide donor (NO). He shows antitumor properties and may be used as an original drug for the therapy of acute coronary syndro...Iron tetranitrosyl complex bearing the thiosulfate ligand (TNIC) is an efficient nitrogen monoxide donor (NO). He shows antitumor properties and may be used as an original drug for the therapy of acute coronary syndrome. In this work, the reaction of the TNIC with adenosine triphosphoric acid (ATP) was studied. Formation of the products for the reaction of ATP with TNIC was shown by electronic microscopy. The kinetics of the reaction was controlled by spectrofluorometric method, and the complexation constant was measured. The mechanism of interaction of ATP with TNIC was proposed, and the relevant kinetic model satisfactorily described the experimental data, which permitted to calculate the rate constants for these process stages. NMR, IR, and M?ssbauer studies were used for determination of the reaction product structure. NMR study showed TNIC interaction only with adenine part of ATP. The method of IR spectroscopy identified both the absence NO in the reaction products and the occurrence of new Fe-S and Fe-N bonds. M?ssbauer study showed that iron in the reaction products was presented by two forms: Fe(II) and Fe(III). Thus, the structures for the [ATP-Fe2+S] and [ATP-Fe3+S] complexes were proposed.展开更多
This paper proposes an alternative analytical spectrophotometric method for the total polyphenol quantification in the aqueous extract of plants. When these extracts are added to solutions of Fe(III), in presence of 1...This paper proposes an alternative analytical spectrophotometric method for the total polyphenol quantification in the aqueous extract of plants. When these extracts are added to solutions of Fe(III), in presence of 1,10-phenanthroline, the absorbance values at 551 nm (A511nm) due to the complexes formed are proportional to the total polyphenol concentration expressed as pyrogallic acid (PA). A typical calibration graph of A511nm values vs. PA is linear from 0.16 to 0.64 mg L-1 (r = 0.994, n = 6) with a limit of detection 0.041 mg L-1. The results of the polyphenol content of the aqueous extracts of twenty medicinal Brazilian plants obtained with the proposed method were compared with values using the Folin-Ciocalteu reagent. A paired t-test revealed no statistically significant difference for the species analyzed. The total antioxidant capacity of the same twenty extracts was determined based on the scavenging of stable radical DPPH.展开更多
At room temperature(25 ℃), urea and ferric chloride hexahydrate(system Ⅰ) or f erric nitrate nonahydrate(system Ⅱ) in a mole ratio of 6∶1 were mixed and ground finely in an agate mortar for 6 hours, a direc t soli...At room temperature(25 ℃), urea and ferric chloride hexahydrate(system Ⅰ) or f erric nitrate nonahydrate(system Ⅱ) in a mole ratio of 6∶1 were mixed and ground finely in an agate mortar for 6 hours, a direc t solid state reaction occurred. IR and elemental analysis confirmed the products obtained are the com- plexes of urea with ir on(Ⅲ).展开更多
基金the Foundation of Returning Personal from Overseas Study of Jiangsu Education Department.
文摘The complex [Fe(C14H14NO2)3]2H2O has been prepared by reaction of N-p-methylphenyl-3-hydroxy-2-ethyl-4-pyridinone with FeCl36H2O. A single-crystal X-ray study shows that the iron atoms lie in a trigonally distorted octahedral environment coordinated to the hydroxy and ketone oxygen atoms of three ligands in the mer configuration Mr=773.57(C42H46N3O8Fe). The crystal is hexagonal with space group P31c; a=15.943(2), c=17.612(4)? V=3877.0(12)?, Z=4, Dc=1.325g/cm3, m=0.445mm-1, F(000)=1634, R=0.0446, wR= 0.1154 for 3085 reflections with I >2s(I). The bond lengths from iron to oxygens are 1.980(1)?for the ketone oxygens and 2.071(1)?for the hydroxy oxygens. The molecule exhibits the expected propeller shape, and the angle of the trigonal twist is 48.37. The dihedral angles are 0.5(2)?between chelate ring plane and pyridine ring plane and 71.31(7)?between pyridine ring plane and benzene ring plane. The solvent H2O(O(3) and O(4)) molecules are linked with O(2) and O(1) by hydrogen bonds with bond lengths 2.900(1) and 2.999(1)? respectively.
文摘A comparative thermal decomposition kinetic investigation on Fe(III) complexes of a antipyrine Schiff base ligand, 1,2-Bis(imino-4’-antipyrinyl)ethane (GA)), with varying counter anions viz. CIO4-, NO3-, SCN-, Cl-, and Br-, has been done by thermogravimetric analysis by using Coats-Redfern equation. The kinetic parameters like activation energy (E), pre-exponential factor (A) and entropy of activation (ΔS) were quantified. On comparing the various kinetic parameters, lower activation energy was observed in second stage as compared to first thermal decomposition stage. The same trend has been observed for pre-exponential factor (A) and entropy of activation (ΔS). The present results show that the starting materials having higher activation energy (E), are more stable than the intermediate products, however;the intermediate products possess well-ordered chemical structure due to their highly negative entropy of activation (ΔS) values. The present investigation proves that the counter anions play an important role on the thermal decomposition kinetics of the complexes.
文摘It has previously been demonstrated that phenanthroline-based ligands used to make gold metallotherapuetics have the ability to exhibit cytotoxicity when not coordinated to the metal center. In an effort to help assess the mechanism by which these ligands may cause tumor cell death, iron binding and removal experiments have been considered. The close linkage between cell proliferation and intracellular iron concentrations suggest that iron deprivation strategies may be a mechanism involved in inhibiting tumor cell growth. With the creation of iron (III) phen complexes, the iron binding abilities of three polypyridal ligands [1,10-phenanthroline (phen), 2,9-dimethyl-1, 10-phenanthroline (methylphen), and 2,9-di-sec-butyl-1, 10-phenanthroline (sec-butylphen)] can be tested via a competition reaction with a known iron chelator. Therefore, iron (III) complexes possessing all three ligands were synthesized. Initial mass spectrometric and infrared absorption data indicate that iron (III) tetrachloride complex ions with protonated phen ligands (RphenH+) were formed: [phenH][FeCl4], [methylphenH][FeCl4], [sec-butylphenH][FeCl4]. UV-vis spectroscopy was used to monitor the stability of the complex ions, and it was found that the sec-butylpheniron complex was more stable than the phen and methylphen analogues. This was based on the observation that free ligand was observed immediately upon the addition of EDTA to the [phenH][FeCl4] and [methylphenH] [FeCl4] complex ions.
文摘Background: Iron deficiency anemia in infants is the most common micronutrient deficiency worldwide. The main cause is low iron intake in the presence of accelerated physiologic growth rate. Objective: The current study aimed at prospectively comparing the efficacy of iron III hydroxide polymaltose syrup (IPS) versus iron III hydroxide polymaltose drops (IPD) in treating iron deficiency among infants attending the hematology outpatient clinic. Our hypothesis was that IPS would be less effective possibly related to the difficulty of giving the medication. Methods: Participants diagnosed with iron deficiency anemia between 11-24 months were randomly assigned to receive either IPS or IPD for 3 months. The main outcome parameter was hemoglobin blood level, while the secondary outcome parameters were: 1) iron;2) ferritin;3) transferrin (i.e.?total iron binding capacity);4) mean corpuscular volume;and 5) red blood cell distribution width. Results: Out of the 104 recruited infants, 55 (52%) completed the study: 29 in the IPS group and26 inthe IPD group. There was no significant difference in the main outcome parameter at either 1 or 3 months of treatment: mean hemoglobin was 10.5 versus 10.7 g/dL within a 1 month treatment, P = 0.4;mean hemoglobin was 11.0 versus 11.1 g/dL within a 3 months of treatment, P = 0.59. Likewise, no significant differences were found with respect to the occurrence of side effects. Conclusion: Oral IPD and IPS are equally effective in treating iron deficiency anemia in infants aged 11 - 24 months.
文摘Hydrotalcite-type anionic clays are a group of important materials used in adsorption processes, mainly for organic pollutants removal due the layered double hydroxide structure. The layer-interlayer interactions provide a structural memory even after dehydration and dehydroxylation process, since a very stable interlayer anions are part of material composition, like the carbonate one. A limited numbers of trivalent modifier cations can replace the aluminium cation due the ionic radii mismatch or oxidation state restrictions. Transition metal cations can replace the aluminium one in octahedral site of hydroxide lamellas in order to improve the adsorptive behaviors. In this work, we have investigate three compositions of carbonated magnesium-aluminium hydrotalcite with dif-ferent iron (III) contents through the co-precipitation method at pH 11 and aging step at 60°C for 6 hours. Thermal analysis was performed aiming the determination of the hydration water and hydroxyl amounts in dried precipitate samples, taking in account the results obtained for X-ray diffractometry, infrared spectroscopy, and nitrogen adsorption-desorption characterization for several thermally treated samples. All of synthesized samples showed high surface areas, even for high temperature of thermal treatment. The co-substitution with iron (III) reduced the temperature of dehydration and dehydroxylation process, but the co-substitution at 5 mol% provides other desirables characteristics, like a more amount of rhombohedral HDL phase and higher porosity, even after the thermal treatment at 500°C for 4 hours. This result makes that composition very applicable as a reusable adsorbent material in order to removal several types of micro-pollutant compounds in aqueous media.
基金financial support from the National Key Research and Development Program of China(2020YFA0710202)the National Natural Science Foundation of China(21978043,U1662130)+1 种基金Inner Mongolia University of Technology Scientific Research Initial Funding(DC2300001240)Talent Introduction Support Project of Inner Mongolia(DC2300001426).
文摘As a common precursor for supercritical CO_(2)(scCO_(2))deposition techniques,solubility data of organometallic complexes in scCO_(2)is crucial for the preparation of nanocomposites.Recently,metal acetylacetonates have shown great potential for the preparation of single-atom catalytic materials.In this study,the solubilities of iron(Ⅲ)acetylacetonate(Fe(acac)3)and nickel(Ⅱ)acetylacetonate(Ni(acac)2)were measured at the temperature from 313.15 to 333.15 K and in the pressure range of 9.5–25.2 MPa to accumulate new solubility data.Solubility was measured using a static weight loss method.The semi-empirical models proposed by Chrastil and Sung et al.were used to correlate the solubility data of Fe(acac)3 and Ni(acac)2.The equations obtained can be used to predict the solubility of the same system in the experimental range.
文摘A new kinetic spectrophotometric method for the determinations of iron(III) has been developed based on its catalytic effects on the oxidation reactions of azocarmine B by KIO4.Under the optimum conditions,the linear range for the determination of Fe3+ by the proposed method is 0～08μg/25ml,and the detection limit is 695×10-10g/ml.The relative standard deviation for 11 replicate determinations of 04 μg Fe(III) is 15%.The results obtained from the studies on the effects by more than 30 kinds of foreign ions indicated that the method free from most interference.The method has been applied for the determination of iron in water,human hair and food samples with relative standard deviations between 08% and 34%,and the recovery between 96% and 104%.
文摘This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsenate varies from 0.5 to 200 mg/l. A kinetic model was considered to describe the arsenates sorption on ZVI material. The kinetics of the arsenate sorption processes were described by the Langmuir kinetic model. The sorption capacity increases with high initial concentration which obtained the maximum sorption 2.1 mg/g at 200 mg/l of arsenate initial concentration. The results show that the rapid initial sorption rates of arsenate were occurred at the beginning of experiments running time, followed by a slower removal that gradually approaches an equilibrium condition. The data from laboratory batch experiments were used to verify the simulation results of the kinetic model resulting in good agreement between measured and modeled results. The results indicate that ZVI could be employed as sorbent materials to enhance the sorption processes and increase the removal rate of arsenate from water.
基金supported by National Basic Research Program of China (973 Program, 2009CB118605)the National Natural Science Foundation of China (30571106)the Innovative Group Grant of Natural Science Foundation of China (30821003)
文摘Aerobic rice has the advantage of saving water. Most published work has focused on improving its yield, while few reported on its micronutrient status. In fact, Fe deficiency is a common nutritional problem in the production of aerobic rice. Short- term hydroponic culture experiments were conducted to study the response of aerobic rice to Fe deficiency and the effect of root exudates from Fe-deficient wheat on its Fe uptake ability. The results indicate that the amount of phytosiderophores （PS） released from aerobic rice did not increase under Fe deficient conditions. The Fe（III） reducing capacity of Fe-deficient aerobic rice did not increase and the solution pH did not decrease significantly. What＇s more, no obvious swelling was observed in the root tips. Aerobic rice did not show special responses to improve their Fe nutrition under Fe deficiency as both strategy I and II plants though they were very sensitive to Fe deficiency. This may be a reason which causes Fe deficiency problem in aerobic rice. However, root exudates from Fe-deficient wheat （PSw） could improve its Fe nutrition in the presence of insoluble Fe（OH）3. This suggests that aerobic rice could utilize Fe activated by PSw.
文摘Iron tetranitrosyl complex bearing the thiosulfate ligand (TNIC) is an efficient nitrogen monoxide donor (NO). He shows antitumor properties and may be used as an original drug for the therapy of acute coronary syndrome. In this work, the reaction of the TNIC with adenosine triphosphoric acid (ATP) was studied. Formation of the products for the reaction of ATP with TNIC was shown by electronic microscopy. The kinetics of the reaction was controlled by spectrofluorometric method, and the complexation constant was measured. The mechanism of interaction of ATP with TNIC was proposed, and the relevant kinetic model satisfactorily described the experimental data, which permitted to calculate the rate constants for these process stages. NMR, IR, and M?ssbauer studies were used for determination of the reaction product structure. NMR study showed TNIC interaction only with adenine part of ATP. The method of IR spectroscopy identified both the absence NO in the reaction products and the occurrence of new Fe-S and Fe-N bonds. M?ssbauer study showed that iron in the reaction products was presented by two forms: Fe(II) and Fe(III). Thus, the structures for the [ATP-Fe2+S] and [ATP-Fe3+S] complexes were proposed.
基金financial support from Brazilian agencies FAPESP(Fundacao de Amparo a Pesquisa do Estado de Sao Paulo),CNPq(Conselho Nacional de Pesquisa e Desenvolvimento Tecnológi-co as CT-Agro and PPBio projects)and FAPEAM(Fundacao de AmparoàPesquisa do Estado do Amazonas)and CENBAM-CNPq-MCTI(Instituto Nacional de Ciencia e Tecnologia de Estudos Integra-dos da Biodiversidade Amazonica).
文摘This paper proposes an alternative analytical spectrophotometric method for the total polyphenol quantification in the aqueous extract of plants. When these extracts are added to solutions of Fe(III), in presence of 1,10-phenanthroline, the absorbance values at 551 nm (A511nm) due to the complexes formed are proportional to the total polyphenol concentration expressed as pyrogallic acid (PA). A typical calibration graph of A511nm values vs. PA is linear from 0.16 to 0.64 mg L-1 (r = 0.994, n = 6) with a limit of detection 0.041 mg L-1. The results of the polyphenol content of the aqueous extracts of twenty medicinal Brazilian plants obtained with the proposed method were compared with values using the Folin-Ciocalteu reagent. A paired t-test revealed no statistically significant difference for the species analyzed. The total antioxidant capacity of the same twenty extracts was determined based on the scavenging of stable radical DPPH.
文摘At room temperature(25 ℃), urea and ferric chloride hexahydrate(system Ⅰ) or f erric nitrate nonahydrate(system Ⅱ) in a mole ratio of 6∶1 were mixed and ground finely in an agate mortar for 6 hours, a direc t solid state reaction occurred. IR and elemental analysis confirmed the products obtained are the com- plexes of urea with ir on(Ⅲ).
