Effects of lanthanum nitrate on growth and chlorophyll fluorescence characteristics of Alternanthera philoxeroides under perchlorate stress

To investigate the effects of exogenous lanthanum (La) on Alternanthera philoxeroides (Mart.) Griseb under perchlorate stress, changes in the growth and physiological parameters were investigated in so...     

Effect of La3+ on seed germination and seedling growth of Salvia miltiorrhiza

The purpose of this study is to determine the effect of La³⁺ solution on seed germination and seedling growth of Salvia miltiorrhiza. Different concentrations of La³⁺ were used on seed by soaking treated to determine which concentration is the most suitable for the growth of S. miltiorrhiza. Results show that the low concentration of La³⁺ displays the promotion effect on S. miltiorrhiza seed germination rate and germination potential, and the promotion effect reaches the highest level when the concentration of La³⁺ solution is 30 mg/L, the germination index and vigor index are the highest in 20 mg/L, and it can also increase the contents of soluble sugar, soluble protein and chlorophyll. Meanwhile, the activity of antioxidant enzyme system (CAT and SOD) are improved, thus the photosynthesis and resistance of plant are enhanced. On the contrary, when the La³⁺ concentration is high, La³⁺ can inhibit plant growth. Thus La³⁺ displays the "homesis effect" on S. miltiorrhiza growth.     

Effects of La3＋ on yield and quality traits of wheat with different gluten types

To test the roles of La3＋ on yield and quality of wheat for different end uses, experiments were conducted using split-plot design for different La3＋ treatments as main plot and different gluten types of wheat as subplot, by foliar spraying La3＋ at jointing stage and filling stage. The results showed that spraying 0.5–1.5 mmol/L La3＋ increased the yield and 1000-kernel weight of wheat of different gluten types. The protein content of strong-gluten wheat Wanmai 33 increased after spraying 0.5–1.5 mmol/L La3＋, which made it achieve the good quality standard of strong-gluten wheat, whereas its LOX and PPO activity reduced, the carotenoid content increased. These La3＋ treatments prolonged the storage period of grain, improved flour nutritional value and the food processing quality. Spraying 0.5–1.5 mmol/L La3＋ also increased flour peak viscosity of medium-gluten wheat Yangmai 158, as improving its starch properties. Spraying La3＋ significantly decreased flour water absorption rate of weak gluten type variety Wanmai 48 to meet the weak-gluten flour standard. The total pentosan content reduced at 1–1.5 mmol/L La3＋, which would be good for making biscuit. Results suggested that spraying appropriate concentration of La3＋ increased wheat yield and benefited wheat quality for different end uses.     

Lanthanum: A novel inducer for enhancement of fungal laccase production by Shiraia bambusicola

Fungal laccases are industrially important inducible enzymes extensively used in the delignification of lignocellulosics, detoxification of environmental wastes and decolorization of textile dyes. The discovery of new inducers is crucial for laccase productivity by filamentous fungi. In this study, a novel laccase-producing strain S8 from a bambusicolous fungus Shiraia bambusicola was identified by using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) as laccase secretion indicator and native polyacrylamide gel electrophoresis. The corresponding full-length cDNA of laccase was cloned and characterized. The effect of lanthanum (LaCl₃) on extracellular laccase activity was tested at the concentration from 0.2 to 2.0 g/L and at different addition time (day 1–4) in the mycelium culture. In the presence of 1.0 g/L La³⁺ at the beginning of the mycelium cultures, the highest laccase activity (2.7 × 10⁴ U/L) is reached after 10 days of cultivation, about tenfold higher compared with non-induced cultures. La³⁺ is shown to be a very strong inducer for fungal laccase activity with no inhibitory effect on fungal growth at the optimized concentration. In vivo, La³⁺ added to the mycelium culture not only promotes a continuous and high expression of laccase gene (lcc1), but also induces a rapid generation of signaling molecules including reactive oxygen species (ROS) and nitric oxygen (NO). Both the NO donor sodium nitroprusside (SNP) and exogenous hydrogen peroxide (H₂O₂) potentiate La³⁺-induced laccase activity and increase membrane permeability of hyphal cells. Moreover, the scavengers such as 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) for NO and vitamin C for ROS suppress the induction. These results suggest that these signals can mediate La³⁺-induced laccase biosynthesis and its secretion. Our study provides a basis for understanding the induction mechanism of La³⁺ on laccase and a practical strategy for enhanced fungal laccase production.     

Induction of osteoblast differentiation in human adipose derived stem cells by lanthanum ions

Adipose derived stem cells represent a readily available source of adult stem cells for various biomedical applications. In this study, the proliferation and osteogenic differentiation potential of lanthanum nitrate（La3＋） on human adipose derived mesenchymal stem cells（hADSCs） were investigated for the first time and compared with that of dexamethasone（Dex）. Our results provided evidence that La3＋ at 50 μmol/L concentration promoted proliferation of hADSCs upto 2.4 fold when treated for 21 d in DMEM medium. Treatment of hADSCs with La3＋ containing osteogenic induction medium（α-MEM with ascorbic acid and β-glycerophosphate） for 7 d resulted in higher calcium deposition than that in the presence of Dex（0.1 μmol/L） as shown by Alizarin red S and von Kossa staining. Scanning electron micrographs also showed more extracellular matrix mineralization in the presence of La3＋. After 7 d of treatment with La3＋（10 μmol/L） the expression of RunX2, osteopontin（OP） and osteocalcin（OC） increased 3.4, 5.5 and 2.7 fold respectively. Our results provided evidence that in the presence of La3＋ osteogenic differentiation occurred earlier than that in the presence of Dex.     

Effects of CeCl3 and LaCl3 on callus and root induction and the physical response of tobacco tissue culture

La³⁺ and Ce³⁺ have positive effects on plant growth and production. Although it is well known that rare earth elements promote cell growth, the biological effects of La³⁺ and Ce³⁺ on callus, shoot and root induction in tobacco are still unclear. The relationships among callus induction, rooting, enzyme activities and stomatal characteristics in tobacco are unknown. The objectives of this study were to identify the relationships between the induction of calluses, shoots, roots, stomata and enzyme activities. The induction percentages of calluses, buds, roots were recorded at 5, 10, 15, 20 and 25 days after La³⁺ and Ce³⁺ treatments. Peroxidase isoenzyme activity was determined by electrophoresis. The characteristics of the stomata were observed under an optical microscope. Our results show that low concentrations of Ce³⁺ (<15 mg/L) result in increases in the induction percentages of calluses, buds and roots, but La³⁺ (>5 mg/L) inhibits the induction of calluses, buds and roots. There are more peroxidase isoenzyme bands in Ce³⁺ treatments than in La³⁺ treatments. This is consistent with the induction percentages of calluses, buds and roots in Ce³⁺ and La³⁺ treatments. High enzyme activities may promote the induction of calluses, buds and roots. The stomata area and stomata number of leaves are significantly different between La³⁺ treatments and Ce³⁺ treatments. La³⁺ improves the stomata area and number. Based on these results, we speculate that La³⁺ may promote the development of the photosynthetic system. Ce³⁺ may promote tobacco growth and rooting by improving enzyme activities.     

Effects of lanthanum on abscisic acid regulation of root growth in Arabidopsis

Rare earth elements(REEs) were reported to have adverse biology effects on plant growth and production. However, whether REEs are involved in plant hormone abscisic acid signal is not clear. Here we reported that REE lanthanum(La) interacted with abscisic acid(ABA) in the regulation of seed germination and root growth in model plant Arabidopsis. La3+at a concentration of 10 μmol/L alleviated ABA depression of seed germination and reversed ABA inhibition of root elongation growth in Arabidopsis. Previous studies showed that ABA could promote root hair development. In the present study, La3+inhibited root hair development promoted by ABA. Moreover, La3+inhibited H2 O2 generation induced by ABA in root cells. Therefore we inferred that La3+might interact with ABA upstream of H2 O2 generation.     

Nano-preparation promoting effectively luminescent properties of one-dimensional rare earth oxides

Rare earth (La,Nd and Tb) oxides with one-dimensional micro/nanostructures were synthesized hydrothermally under facile and mild conditions with two surfactants, and characterized by X-ray diffraction (XRD), thermal gravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence. The results showed that the synthesized rare earth oxides behaved regular nano-and micro-scale structures. And the morphologies of samples depended on the radii of rare earth ions, with the help of two surfactants of sodium dodecyl sulfonic and PEG 600. Nanocrystalline La2O3:Eu3+ possessed good photoluminescence (PL) property and might be used as a nanosized phosphor, its PL intensity was altered by the doping Eu3+ concentration and the optimum concentration of Eu3+ was 3 mol.%. In comparison with bulk Eu3+/La2O3, Eu3+/nano-La2O3 showed better photoluminescence property, nearly equal to that of nanocrtstal-line La2O3:Eu3+. Tb4O7 microwires showed interesting photoluminescence properties.     

Synthesis of 4-acylpyrazolone Schiff base ligand grafted silica and selectivity in adsorption of lanthanides from aqueous solutions

The Schiff base form of the 4-acylpyrazoione ligand was immobilized on the silica surface by reaction of 3-aminopropyl silica with 4-acetyl-5-methyl-2-phenyl-2,4-dihydro-pyrazol-3-one in 97% yield, producing grafted silica with 0.77 mmol/g ligand loading. This surface modified silica was shown to be selective in the adsorption of Yb3+ ions from dilute aqueous solutions, for which 98% adsorption was observed from a 1.0×10-5 mol/L aq. solution at pH 6.7, after 24 h at room temperature. Six other lanthanides studied Eu3+, Gd3+, Nd3+, Tb3+,Sm3+ and La3+ showed moderate to weaker adsorptions of 39%, 28%, 16%, 12%, 11% and 5% respectively under similar conditions.     

Adsorption behavior of rare earth elements using polyethyleneglycol (phosphomolybdate and tungstate) heteropolyacid sorbents in nitric solution

A new type of crystalline sorbent was prepared by the reaction of polyethyleneglycol (PEG) with phosphomolybdic (PMo) and phosphotungstic (PW) heteropolyacids. The morphology of the obtained sorbents was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It has been shown that a complexing reaction occurs between PEG and the heteropolyacids. By using these sorbents, the adsorption behaviors of rare earth elements in nitric solution were studied. The effects of temperature, contact time, nitric acid and initial metal ion concentration on the adsorption were investigated. In 0.1–5.0 mol L^− 1HNO₃, the adsorption percentage decreases with the increase of acid concentration. H,PEG400,PW and H,PEG400,PMo exhibited a different selectivity for rare earth metals, with H,PEG400,PW adsorbing in the order of La³⁺ > Y³⁺ > Pr³⁺ > Gd³⁺ > Sm³⁺, and H,PEG400,PMo in the order of Y³⁺ > La³⁺ > Pr³⁺ > Gd³⁺ > Sm³⁺. The experimental maximum adsorption capacities of the sorbents are in the range of 90–225 mg g^− 1 for Y³⁺, La³⁺, Pr³⁺, Sm³⁺ and Gd³⁺. In all cases, the maximum adsorption capacities of H,PEG400,PW are near to those of H,PEG400,PMo. The equilibrium data were evaluated according to the Freundlich and Langmuir isotherms and the Langmuir equation gave a better fit and modeled the adsorption well.     

Effects of cerium on growth and physiological characteristics of Anabaena flosaquae

In the present study, the effects of cerium (Ce) on the growth and physiological changes were investigated in the cyanobacterium Anabaena flosaquae (A. flosaquae) during a 17-day period. The results showed that the content of chlorophyll a (chl-a) and activity of anti-oxidase (e.g. superoxide dismutase, peroxidase, and catalase) increased with Ce3+ concentration in the range of 0.05 to 0.1 mg/L and the growth of A. flosaquae was stimulated. While at around 5 mg/L, the content of malondiadehyde (MDA) increased significantly but the activ-ity of antioxidase reduced, which resulted in the ruin of antioxidant defense system. Compared to the control (Ce3+-free), the population size of live cells declined significantly. Microcystin-LR (MC-LR), the most common and toxic cyanotoxins produced by A. flosaquae, was de-tected and the highest content of MC-LR was observed in 10 mg/L Ce3+ treatment. These results implied that the aqueous environment might suffer a more negative ecological impact when exposed to relatively low Ce3+ concentrations (<0.1 mg/L).)     

Trace detection of Ce3+ by adsorption strip voltammetry at a carbon paste electrode modified with ion imprinted polymers

To develop a convenient method for sensitive and selective determination of Ce3+ in aqueous phase with complicated matrices, a carbon paste electrode(CPE) modified with ion imprinted polymers(IIPs) were fabricated. The polymers were prepared by precipitation polymerization using Ce3+ as template, allyl phenoxyacetate(APA) as monomer, ethylene glycol dimethacrylate(EGDMA) as crosslinker and azobisisobutyronitrile(AIBN) as initiator under the molar ratio of Ce3+, APA and EGDMA as 1:4:40, respectively. Ce~(3+) was detected directly by differential pulse adsorptive stripping voltammetry(DPASV) and its oxidation peak appears at about 0.93 V. All parameters affecting the sensor's response are optimized and a calibration curve is plotted at a linear range of 1.0 × 10~(-6)-1.0 x 10~(-5) mol/L and 1.0×10~(-5)-2.0 × 10~(-4)mol/L with the detection limit of 1.5 × 10~(-7) mol/L. All other rare earth ions have no interference with the determination of Ce~(3+) even at a concentration 500 times higher than that of Ce~(3+).This sensor was successfully applied to determination of Ce~(3+) in two catalyst sample solutions with RSD≤3.3%(n = 5)and recoveries in the range of 99.2%-106.5% at our optimal conditions.     

Dissolution behaviour of a beryl ore for optimal industrial beryllium compound production

This study involves the leaching of the beryl ore with sulphuric acid (H₂SO₄) solution for predicting optimal beryllium extraction conditions with the aim of assessing the importance of leachant concentration, reaction temperature and particle size on the extent of dissolution. A kinetic model to represent the effects of these variables on the leaching rate was developed. It was observed that the dissolution of beryl ore increases with increasing H₂SO₄ concentration, temperature, decreasing particle size and solid to liquid ratio. At optimal leaching conditions, 89.3% of the ore was reacted by 1.25?mol/L at 75°C temperature and 120 minutes with moderate stirring, where 1612.0?mg/L Be²⁺, 786.7?mg/L Al³⁺, 98.1?mg/L Fe³⁺ and 63.4?mg/L Ag⁺ were found as major species in the leach liquor. The unleached products constituting about 10.7% were examined by X-ray diffraction (XRD) and found to contain primarily, siliceous compounds such as Xonotlite, Antigorite, Chrysolite and Kaolinite.     

White-light emitting single-phase phosphor La3Si6N11:Dy3+,Tb3+: Color tunable emission,thermal stability and energy transfer process

A novel white-light emitting single-phase phosphor La₃Si₆N₁₁:Dy³⁺, exhibiting two emission peaks centering at 475 and 575 nm, was prepared via conventional solid-state reactions. The structure and morphology of La₃Si₆N₁₁:Dy³⁺/Tb³⁺ were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The emission colors can be tuned from white to yellow-green through increasing the Tb³⁺ concentration in La₃Si₆N₁₁:Dy³⁺,Tb³⁺. The mechanism of energy transfer (ET) from Dy³⁺ to Tb³⁺ is confirmed according to the excitation, emission spectra and decay lifetimes curve. The temperature-dependent luminescence measurements of La_2.83Si₆N₁₁:0.1Dy³⁺,0.07Tb³⁺ were also performed, and a good thermal stability is shown, suggesting superior properties for the application as white light-emitting diodes (w-LEDs) phosphor.     

Green mediated synthesis of lanthanum doped zinc oxide: Study of its structural,optical and latent fingerprint application

The present paper summarises the synthesis of La³⁺ doped zinc oxide nanoparticles using Aloe vera gel by solution combustion method and the characterization using a powder X-ray diffractometer (PXRD), a transmission electron microscope (TEM), an X-ray photometric spectrometer (XPS), a Raman spectrometer and their applications in optical devices and latent fingerprinting. PXRD pattern confirms the crystallite size of La³⁺ doped ZnO varies from 13 to 20 nm. Crystallite size varies inversely with doping concentration. Photoluminescence properties are found to be the maximum for 2 mol% doping concentration. PL spectra extends the use of ZnO:La³⁺ nanoparticles in blue green LED. These nanoparticles also have superior property as a fluorescent labels in fingerprints.     

Prevention of La^3＋ on DNA Damage Caused by Hg^2＋ from Fish Intestines

Recent studies have shown that heavy metals havebecome the most important contaminants in the environ-ment.Some heavy metals ,such as Pb, Cd, Hg, As ,Co,and Cr have genetic toxicity. They disturb DNAmetabolismand lead to aberrance of chromosome andDNA[1].…     

A fluorescent probe based on a spiropyran for sensitive detection of Ce~(3+) ion

A spiropyran-based probe was developed.It serves as a fluorescence turn-on probe for selective detection of Ce~(3+) in both ethanol and aqueous(water/ethanol,1:9 or 9:1,v/v) media.Ce~(3+) can induce photochromism of the probe though the probe exhibits negligible photochromic property by itself.The probe is sensitive to Ce~(3+) and the detection limit reaches 1.7 μmol/L.It exhibits a high selectivity for Ce~(3+)ion over other common metal cations including Li~+,Na~+,Ag~+,Sr~(2+),Ni~(2+),Co~(2+),Hg~(2+),Zn~(2+),Cr~(3+),Al~(3+),Fe~(3+) and Bi~(3+) and lanthanide ions Nd~(3+),Yb~(3+) and La~(3+).The probe may be used for quantitative determination of the concentration of Ce~(3+) ion in a range of 1-10 μmol/L and for application to environmental water samples.Sensing mechanism of the probe towards Ce~(3+) ion is proposed.     

Effect of Li+ ion concentration on upconversion emission and temperature sensing behavior of La2O3:Er3+ phosphors

The effects of Li~+ co-doping concentration on the structure, upconversion luminescence and temperature sensing behavior of Er~(3+):La_2O_3 phosphors were investigated. X-ray diffraction and scanning electron microscopy observations reveal that Li~+ ion co-doping can change the lattice parameter of La_2O_3 host and increase the particle size of the samples. The optical investigation shows that co-doping of Li~+ ions can enhance the upconversion emission of Er~(3+) ions in La_2O_3 matrix effectively. Most importantly, the temperature sensing sensitivity of the samples is found to be dependent on Li~+ co-doping concentration,when the emission intensity ratio of the(~2H_(11/2)→~4 I_(15/2)) and(~4 S_(3/2)→~4 I_(15/2)) transitions of Er~(3+) is chosen as the thermometric index. Both of the optimum upconversion luminescence and temperature sensing sensitivity are obtained for 7 mol% Li~+ co-doped sample. When the Li~+ concentration is beyond 7 mol%,both the quenching in upconversion intensity and the degradation of temperature sensitivity are observed, which may be due to the serious distortion in local crystal field around Er~(3+) ions caused by the excess Li~+ ions.     

酶催化分光荧光法测定环境水中痕量铬(Ⅵ)

铬（Ⅳ）对血红蛋白模拟酶催化荧光体系具有强烈的猝灭作用, 据此建立了一种酶催化分光荧光法测定铬（Ⅳ）的新方法。研究了溶液酸度、L-酪氨酸浓度、血红蛋白浓度、H₂O₂浓度及反应时间等因素对体系的影响。在pH10.4的NH₃·H₂O-NH₄Cl缓冲溶液中, 当L-酪氨酸、血红蛋白和H₂O₂的浓度分别为1.4×10^-4mol/L、1.0×10^-6mol/L和3.5×10^-5mol/L时, 测定铬（Ⅳ）的线性范围为2.0×10^-6～1.0×10^-4mol/L, 检出限为1.1×10^-8mol/L。1000倍NO₃^-、SO₄^2-、Na⁺、K⁺、Cl^-、Br^-, 300倍PO₄^3-、Al³⁺、NH₄⁺, 50倍Mn²⁺、Mg²⁺、Fe²⁺、Cu²⁺, 1倍Fe³⁺对铬（Ⅳ）的测定没有干扰。干扰较大的Fe³⁺, 可加入过量的柠檬酸掩蔽。对浓度为4.8×10^-5mol/L的铬（Ⅳ）进行11次平行测定, 其相对标准偏差为2.8%。该法已成功地应用于环境水样中铬（Ⅳ）含量的测定。     

Structure and luminescence properties of color-tunable phosphor Sr2La3(SiO4)3F:Tb3+,Sm3+

A series of single-phase and color-tunable phosphors Sr₂La₃(SiO₄)₃F:0.15Tb³⁺,xSm³⁺(SLSOF:0.15Tb³⁺,xSm³⁺) was prepared using solid-state route.The X-ray diffraction(XRD) was used to characterize the phase of the as-prepared samples.The synthesized phosphors have apatite-type structure without other impurities.Sm³⁺ and Tb³⁺ ions substitute La³⁺ into the lattice and form a single...