Combined chemical analyses and biological measurements were utilized to investigate potential toxicological effects and possible mechanisms involved in risk assessment of rare earth elements （REEs） on Viciafaba L. s...Combined chemical analyses and biological measurements were utilized to investigate potential toxicological effects and possible mechanisms involved in risk assessment of rare earth elements （REEs） on Viciafaba L. seedlings, which were hydroponically cultivated and exposed to various concentrations of lanthanum （La） for 15 days. The results showed that La contents in both the solution and roots increased with the increase of extraneous La, contributing to hormetic dose responses of superoxide dismutase （SOD）, catalase （CAT）, guaiacol peroxidase （GPX）, ascorbate peroxidase （APX） and endoprotease （EP） isozymes activities, and HSP 70 production enhanced at low doses but suppressed at higher doses of La. These physiological responses constituted antioxidant and detoxification systems against La-induced oxidative stress. The elevated La levels also contributed to oxidatively modified proteins, which were most responsible for subsequent cell death and growth retardation of the roots. By combination of hormetic and traditional threshold dose levels, the threshold dose range was deduced to be 108-195 μg La/g dry weight in the roots, corresponding to 0.90-3.12 mg/L of soluble La in the culture solution. It suggests that persistent applications of REEs may lead to potential ecological risk in the environment.展开更多
A new method for the determination of trace non-rare earth elements (NREEs) impurities in high-purity lanthanum oxide by HPLC combined with ICP-AES is proposed. The chromatographic retention behaviors of matrix (La) a...A new method for the determination of trace non-rare earth elements (NREEs) impurities in high-purity lanthanum oxide by HPLC combined with ICP-AES is proposed. The chromatographic retention behaviors of matrix (La) and NREEs were studied using 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (P507) chelating resin as the stationary phase and dilute nitric acid as the mobile phase. It is found that the use of pH 1.7 nitric acid enables effective elution of NREEs from HPLC column, but the lanthanum remains on the column. The experimental results show that a favorable separation between matrix lanthanum and NREEs can be obtained within 15 min. The method proposed is applied to the determination of 8 NREEs impurities in high-purity La2O3. The recoveries of 8 NREEs are in the range of 90 % similar to 110 %.展开更多
The present work aimed at using rare earth lanthanum salt and trimethoxy（viny）silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate.The corrosion...The present work aimed at using rare earth lanthanum salt and trimethoxy（viny）silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate.The corrosion resistance was assessed by electrochemical impedance spectroscopy（EIS） and neutral salt spray tests（NSS）.Scanning electron microscopy（SEM） was used to characterize the sample surfaces.The organic coating adhesion on the panel was also investigated via varnishes-cross cut tests.The results indicated that rare earth and silane two-step treatment gave more effective anticorrosion performance than Cr, which also provided good paint adhesion.The coating formation mechanism was also discussed.展开更多
New polyoxometalate α-K 12H 3[Y(BW 11O 39) 2]·25H 2O was synthesized and treated by high temperature gaseous rare earth permeation to prepare tungsten bronze K 0.475WO 3. XRD, TG-DTA, XPS, ...New polyoxometalate α-K 12H 3[Y(BW 11O 39) 2]·25H 2O was synthesized and treated by high temperature gaseous rare earth permeation to prepare tungsten bronze K 0.475WO 3. XRD, TG-DTA, XPS, 183W-NMR,CV and AC impedance spectra were used to characterize the resulting material. The results of XPS indicate that La has permeated and diffused into the body of the sample and exists in the forms of binding with other components. The crystal structure parameters of K 0.475WO 3 were obtained by the analysis of XRD, which shows tetragonal crystal system with lattice parameters: a=12 28 nm, c=3.833 nm, V=578.48 nm -3. The conductivities calculated from the results of AC impedance spectra of the material increase with the increasing of temperature, which shows a semiconductor character.展开更多
On the basis of investigated enhancement effect of La, Nd, Eu, and Y on Sm determination with monoxide molecular emission spectrometry, La was selected as enhancement agent and chemical interference inhibitor. In the ...On the basis of investigated enhancement effect of La, Nd, Eu, and Y on Sm determination with monoxide molecular emission spectrometry, La was selected as enhancement agent and chemical interference inhibitor. In the presence of La, dual wavelength mothod was introduced to eliminate the spectral interference on Sm by other elements. A new method was established to determine samarium in high yttrium rare earth samples with satisfactory results.展开更多
The adsorption characteristics of rare earth ion La(Ⅲ) on Yunnan bowl tea surface from aqueous solution and effects of various surfactants on the adsorption were studied. It was found that Yunnan bowl tea can adsorb ...The adsorption characteristics of rare earth ion La(Ⅲ) on Yunnan bowl tea surface from aqueous solution and effects of various surfactants on the adsorption were studied. It was found that Yunnan bowl tea can adsorb strongly La(Ⅲ) and pH may affect drastically the adsorption amount of La(Ⅲ). The adsorption law of La(Ⅲ) on Yunnan bowl tea surface follows the Langmuir equation. The maximum adsorption amount of La(Ⅲ) can reach 15 mg·g (-1). A comprehensive adsorption model is suggested according to the experimental results.展开更多
White nano-titanium organic compound-gel with steady performance was synthesized by sol-gel method. This gel has good absorbency to ultraviolet rays. Specially, the absorption wavelength of the organic gel shifted fro...White nano-titanium organic compound-gel with steady performance was synthesized by sol-gel method. This gel has good absorbency to ultraviolet rays. Specially, the absorption wavelength of the organic gel shifted from 250.9 to 254.3 nm(doped with La) and 257.8 nm(doped with Ce), respectively and the absorption peak broadened. The broadening extent has direct ratio with the doping content. It is indicated that when the thickness of the organic gel coat is 60 μm, 98.8% ultraviolet with radiation intensity of 17.2 μW·cm -2 is blocked off. The TEM test shows that the diameter of the titanium organic gel doped with lanthanum is about 5 nm and the granules are uniform. It is indicated that by X-ray this organic substance is amorphous state and it will form nano-TiO_2 with anatase structure calcined at 450 ℃.展开更多
The interaction relation between lanthanum and the constituent elements of Sn-Pb alloy system was analyzed by using the thermodynamic models including Miedema formation energy model for binary system, Tanaka modificat...The interaction relation between lanthanum and the constituent elements of Sn-Pb alloy system was analyzed by using the thermodynamic models including Miedema formation energy model for binary system, Tanaka modification by excess entropy and the Chou geometric model for ternary system. The thermodynamic calculaton results show that lanthanum has higher affinity for Sn in the Sn-Pb system. This is an important foundation for the improvement of the metallurgical properties of Sn-Pb solder alloy by adding rare earth elements.展开更多
The effects of exogenous La on the fertility parameters such as cation exchange capacity ( CEC), exchangeable basic cations, and exchangeable acidity in red soil and paddy soil were studied with soil column simulation...The effects of exogenous La on the fertility parameters such as cation exchange capacity ( CEC), exchangeable basic cations, and exchangeable acidity in red soil and paddy soil were studied with soil column simulation. The results show that with increasing amount of the added La, the proportion of exchangeable La in soils increases and there is more exchangeable La in red soil than in paddy soil. When the concentration of La is more than 600 mg(.)kg(-1) the proportion of exchangeable La almost remains constant. When the concentration of La is less than 1200 mg(.)kg(-1) there is no significant effect on CEC in red soil. But when the concentration of La is more than 1200 mg(.)kg(-1,) it has significant effect on CEC in paddy soil. The application of La resulted in increasing exchangeable aluminum, Ca and Mg in soil solution, and decreasing exchangeable Ca and Mg retained in soils. But when the concentration of La is less than 150 mg(.)kg(-1), it has no significant influence on CEC, exchangeable Ca and Mg, and exchangeable acidity in red soil and paddy soil.展开更多
The effect of La 3+ and Eu 3+ on the rooting of Eriobotrya japonica Lindl. plantlet in vitro was studied with adding La 3+ and Eu 3+ to the rooted medium. The rooting rate, the number of root and the lengt...The effect of La 3+ and Eu 3+ on the rooting of Eriobotrya japonica Lindl. plantlet in vitro was studied with adding La 3+ and Eu 3+ to the rooted medium. The rooting rate, the number of root and the length of root were studied after transplanting 20 d. The activity of peroxidase, nitrate reductase and fresh weight of roots were determined after transplanting 44 d. The results show that the optimum concentration range of La 3+ (1.0～3.0 μmol·L -1), Eu 3+ (2.0～3.0 μmol·L -1) in the rooted medium can increase the rooting rate and the fresh weight of roots, and promote the length of root and raise the activities of peroxidase and nitrate reductase significantly. La 3+ has more effect in improving the rooting rate, root length and the activities of peroxidase and less effect in promoting root fresh weight and the activities of nitrate reductase than Eu 3+.展开更多
The effects of La on some hydrolytic enzyme activities in red soil were studied in incubation and pot culture experiments. In the incubation experiment, La slightly stimulates the activities of urease and acidic phosp...The effects of La on some hydrolytic enzyme activities in red soil were studied in incubation and pot culture experiments. In the incubation experiment, La slightly stimulates the activities of urease and acidic phosphatase in soil and strongly stimulates sucrase activity in soil. In the pot culture experiment, La stimulates the activities of urease, acidic phosphatase and sucrase to different degrees. The stimulative effects of rare earth elements (REE) on hydrolytic enzyme activities in soil may result in increasing yield of crops.展开更多
The paper briefly dealt with relieving toxic effects of La on high aquatic plant-Hydrocharis dubia B L. Backer growing in the solution containing different concentration of Ni. The results show that La can relieve the...The paper briefly dealt with relieving toxic effects of La on high aquatic plant-Hydrocharis dubia B L. Backer growing in the solution containing different concentration of Ni. The results show that La can relieve the reduction of chlorophyll content, the accumulation of MDA(malondiadehyde) and the elevation of relative membrane penetrability (RMP). After adding 10 mg . L-1 La to the solution, the activities of SOD and CAT in the leaves of Hydrocharis dubia B L. Backer increases compared with those of the single treatment of Ni, while the activity of POD decreases. It reveals that la enhances the abilities of scavenging the activated oxygen in the plant and alleviates the damage to the membranes. The soluble protein content with Ni and La compound treatment is higher than that of single Ni does, and proline content is contrary to the soluble protein content. So La improves the resistance of Hydrocharis dubia B. L. Backer to the stress of Ni. However, La can aggravate the damage to the cells under the extremely high concentration of Ni treatment.展开更多
The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that ...The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that the valence of lanthanum changes during the activation processes. As the temperature increases, the lattice oxygen in La 2O 3 is dissociated, resulting in partial reduction of the lanthanum to LaO x(x <3/2). In addition, the lanthanum rich phase diffuses from bulk into the surface of the sample. The lack of lattice oxygen in this phase has a favorable effect on emission, which leads to a lower work function for the Mo La 2O 3 cathode.展开更多
基金supported by the National Natural Science Foundation of China (No. 20877032)the Foundation of State Key Laboratory of Pollution Control and Resources Reuse of China (No. PCRRF08011)
文摘Combined chemical analyses and biological measurements were utilized to investigate potential toxicological effects and possible mechanisms involved in risk assessment of rare earth elements （REEs） on Viciafaba L. seedlings, which were hydroponically cultivated and exposed to various concentrations of lanthanum （La） for 15 days. The results showed that La contents in both the solution and roots increased with the increase of extraneous La, contributing to hormetic dose responses of superoxide dismutase （SOD）, catalase （CAT）, guaiacol peroxidase （GPX）, ascorbate peroxidase （APX） and endoprotease （EP） isozymes activities, and HSP 70 production enhanced at low doses but suppressed at higher doses of La. These physiological responses constituted antioxidant and detoxification systems against La-induced oxidative stress. The elevated La levels also contributed to oxidatively modified proteins, which were most responsible for subsequent cell death and growth retardation of the roots. By combination of hormetic and traditional threshold dose levels, the threshold dose range was deduced to be 108-195 μg La/g dry weight in the roots, corresponding to 0.90-3.12 mg/L of soluble La in the culture solution. It suggests that persistent applications of REEs may lead to potential ecological risk in the environment.
文摘A new method for the determination of trace non-rare earth elements (NREEs) impurities in high-purity lanthanum oxide by HPLC combined with ICP-AES is proposed. The chromatographic retention behaviors of matrix (La) and NREEs were studied using 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (P507) chelating resin as the stationary phase and dilute nitric acid as the mobile phase. It is found that the use of pH 1.7 nitric acid enables effective elution of NREEs from HPLC column, but the lanthanum remains on the column. The experimental results show that a favorable separation between matrix lanthanum and NREEs can be obtained within 15 min. The method proposed is applied to the determination of 8 NREEs impurities in high-purity La2O3. The recoveries of 8 NREEs are in the range of 90 % similar to 110 %.
文摘The present work aimed at using rare earth lanthanum salt and trimethoxy（viny）silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate.The corrosion resistance was assessed by electrochemical impedance spectroscopy（EIS） and neutral salt spray tests（NSS）.Scanning electron microscopy（SEM） was used to characterize the sample surfaces.The organic coating adhesion on the panel was also investigated via varnishes-cross cut tests.The results indicated that rare earth and silane two-step treatment gave more effective anticorrosion performance than Cr, which also provided good paint adhesion.The coating formation mechanism was also discussed.
文摘New polyoxometalate α-K 12H 3[Y(BW 11O 39) 2]·25H 2O was synthesized and treated by high temperature gaseous rare earth permeation to prepare tungsten bronze K 0.475WO 3. XRD, TG-DTA, XPS, 183W-NMR,CV and AC impedance spectra were used to characterize the resulting material. The results of XPS indicate that La has permeated and diffused into the body of the sample and exists in the forms of binding with other components. The crystal structure parameters of K 0.475WO 3 were obtained by the analysis of XRD, which shows tetragonal crystal system with lattice parameters: a=12 28 nm, c=3.833 nm, V=578.48 nm -3. The conductivities calculated from the results of AC impedance spectra of the material increase with the increasing of temperature, which shows a semiconductor character.
文摘On the basis of investigated enhancement effect of La, Nd, Eu, and Y on Sm determination with monoxide molecular emission spectrometry, La was selected as enhancement agent and chemical interference inhibitor. In the presence of La, dual wavelength mothod was introduced to eliminate the spectral interference on Sm by other elements. A new method was established to determine samarium in high yttrium rare earth samples with satisfactory results.
文摘The adsorption characteristics of rare earth ion La(Ⅲ) on Yunnan bowl tea surface from aqueous solution and effects of various surfactants on the adsorption were studied. It was found that Yunnan bowl tea can adsorb strongly La(Ⅲ) and pH may affect drastically the adsorption amount of La(Ⅲ). The adsorption law of La(Ⅲ) on Yunnan bowl tea surface follows the Langmuir equation. The maximum adsorption amount of La(Ⅲ) can reach 15 mg·g (-1). A comprehensive adsorption model is suggested according to the experimental results.
文摘White nano-titanium organic compound-gel with steady performance was synthesized by sol-gel method. This gel has good absorbency to ultraviolet rays. Specially, the absorption wavelength of the organic gel shifted from 250.9 to 254.3 nm(doped with La) and 257.8 nm(doped with Ce), respectively and the absorption peak broadened. The broadening extent has direct ratio with the doping content. It is indicated that when the thickness of the organic gel coat is 60 μm, 98.8% ultraviolet with radiation intensity of 17.2 μW·cm -2 is blocked off. The TEM test shows that the diameter of the titanium organic gel doped with lanthanum is about 5 nm and the granules are uniform. It is indicated that by X-ray this organic substance is amorphous state and it will form nano-TiO_2 with anatase structure calcined at 450 ℃.
文摘The interaction relation between lanthanum and the constituent elements of Sn-Pb alloy system was analyzed by using the thermodynamic models including Miedema formation energy model for binary system, Tanaka modification by excess entropy and the Chou geometric model for ternary system. The thermodynamic calculaton results show that lanthanum has higher affinity for Sn in the Sn-Pb system. This is an important foundation for the improvement of the metallurgical properties of Sn-Pb solder alloy by adding rare earth elements.
文摘The effects of exogenous La on the fertility parameters such as cation exchange capacity ( CEC), exchangeable basic cations, and exchangeable acidity in red soil and paddy soil were studied with soil column simulation. The results show that with increasing amount of the added La, the proportion of exchangeable La in soils increases and there is more exchangeable La in red soil than in paddy soil. When the concentration of La is more than 600 mg(.)kg(-1) the proportion of exchangeable La almost remains constant. When the concentration of La is less than 1200 mg(.)kg(-1) there is no significant effect on CEC in red soil. But when the concentration of La is more than 1200 mg(.)kg(-1,) it has significant effect on CEC in paddy soil. The application of La resulted in increasing exchangeable aluminum, Ca and Mg in soil solution, and decreasing exchangeable Ca and Mg retained in soils. But when the concentration of La is less than 150 mg(.)kg(-1), it has no significant influence on CEC, exchangeable Ca and Mg, and exchangeable acidity in red soil and paddy soil.
文摘The effect of La 3+ and Eu 3+ on the rooting of Eriobotrya japonica Lindl. plantlet in vitro was studied with adding La 3+ and Eu 3+ to the rooted medium. The rooting rate, the number of root and the length of root were studied after transplanting 20 d. The activity of peroxidase, nitrate reductase and fresh weight of roots were determined after transplanting 44 d. The results show that the optimum concentration range of La 3+ (1.0～3.0 μmol·L -1), Eu 3+ (2.0～3.0 μmol·L -1) in the rooted medium can increase the rooting rate and the fresh weight of roots, and promote the length of root and raise the activities of peroxidase and nitrate reductase significantly. La 3+ has more effect in improving the rooting rate, root length and the activities of peroxidase and less effect in promoting root fresh weight and the activities of nitrate reductase than Eu 3+.
文摘The effects of La on some hydrolytic enzyme activities in red soil were studied in incubation and pot culture experiments. In the incubation experiment, La slightly stimulates the activities of urease and acidic phosphatase in soil and strongly stimulates sucrase activity in soil. In the pot culture experiment, La stimulates the activities of urease, acidic phosphatase and sucrase to different degrees. The stimulative effects of rare earth elements (REE) on hydrolytic enzyme activities in soil may result in increasing yield of crops.
文摘The paper briefly dealt with relieving toxic effects of La on high aquatic plant-Hydrocharis dubia B L. Backer growing in the solution containing different concentration of Ni. The results show that La can relieve the reduction of chlorophyll content, the accumulation of MDA(malondiadehyde) and the elevation of relative membrane penetrability (RMP). After adding 10 mg . L-1 La to the solution, the activities of SOD and CAT in the leaves of Hydrocharis dubia B L. Backer increases compared with those of the single treatment of Ni, while the activity of POD decreases. It reveals that la enhances the abilities of scavenging the activated oxygen in the plant and alleviates the damage to the membranes. The soluble protein content with Ni and La compound treatment is higher than that of single Ni does, and proline content is contrary to the soluble protein content. So La improves the resistance of Hydrocharis dubia B. L. Backer to the stress of Ni. However, La can aggravate the damage to the cells under the extremely high concentration of Ni treatment.
文摘The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that the valence of lanthanum changes during the activation processes. As the temperature increases, the lattice oxygen in La 2O 3 is dissociated, resulting in partial reduction of the lanthanum to LaO x(x <3/2). In addition, the lanthanum rich phase diffuses from bulk into the surface of the sample. The lack of lattice oxygen in this phase has a favorable effect on emission, which leads to a lower work function for the Mo La 2O 3 cathode.
