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.     

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...     

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.     

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.     

Magnetoelectric,Raman, and XPS Properties of Pb0.7Sr0.3[(Fe2/3Ce1/3)0.012Ti0.988]O3 and Pb0.7Sr0.3[(Fe2/3La1/3)0.012Ti0.988]O3 Nanoparticles

The Pb_0.7Sr_0.3[(Fe_2/3Ce_1/3)_0.012Ti_0.988]O₃ (PSFCT) and Pb_0.7Sr_0.3[(Fe_2/3La_1/3)_0.012Ti_0.988]O₃ nanoparticles were prepared by chemical synthesis route using polyvinyl alcohol as surfactant. X-ray diffraction pattern has been used to analyze the phase structure and average particles size. The phase structure is also confirmed by Raman spectra. The chemical states of Pb²⁺, Sr²⁺, Fe³⁺; Ti⁴⁺, Ce³⁺, La³⁺, and oxygen ions have been analyzed by X-ray photoelectron spectroscopy. The magnetoelectric coupling effect is confirmed by magnetic phase transition near ferroelectric phase-transition temperature. The magnetoelectric effect is also confirmed by measuring the value of magnetoelectric coefficient (α _E) as the function of applied dc magnetizing field under the influence of ac magnetic field of 10 Oe and frequencies of 847 and 997 Hz. The higher value of α _E is observed in PSFCT sample.     

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.     

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.     

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.     

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.     

Effects of chitosan-RE3+-bentonite on growth of Chlorella vulgaris

Bentonite was modified with chitosan and REIs (La³⁺, Ce³⁺) to form chitosan-RE³⁺-bentonite (CRB). CRB were characterized by DSC and FT-IR. And the inhibitory effects of CRB on the growth of Chlorella vulgaris were investigated. The results indicated that CRB could inhibit the growth of Chlorella vulgaris. The relative conductivity and the generation of malondialdehyde (MDA) increased. In addition, the superoxide dismutase (SOD) and peroxidase (POD) activities decreased. So CRB could be a promising algaecide agent.     

Synthesis and luminescence properties of novel Ce3+-doped Yb3Al5–xGaxO12 garnets with very fast decay time

A novel series of Ce~(3+)-doped Yb_3 Al_(5-x)Ga_xO_(12)(x = 0, 1,2, 3,4, 5) powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The ytterbium aluminum garnets were characterized by X-ray powder diffraction, UV-Vis diffuse reflectance spectra, photoluminescence spectra and decay curves. Moreover, the substitution effect for the Al~(3+) sites with Ga~(3+) in 0.5 at%Ce:Yb_3 Al_(5-x)Ga_xO_(12)(x = 0,1, 2, 3, 4, 5) garnets were discussed. With the increase of Ga~(3+) ion concentration, the visible absorption peaks within 400-450 nm have blue shift phenomenon,while the absorption peaks in the range of 330-350 nm and the absorption band edge red shifts.Furthermore, the short decay times are very short with less than 10 ns due to the Yb~(3+) + Ce~(3+)→ Yb~(2+) + Ce~(4+) electron transfer reaction.     

Electrical properties of iron doped apatite-type lanthanum silicates

The effect of Fe doping on the electrical properties of lanthanum silicates was investigated. The apatite-type lanthanum silicates La10Si6-xFexO27-x/2 (x=0.2, 0.4, 0.6, 0.8, 1.0) were synthesized via sol-gel process. The unit cell volume increased with Fe doping because the ionic radius of Fe3+ ion is larger than that of Si4+ ion. The conductivities of La10Si6-xFexO27-x/2first increased and then decreased with the in-creasing of Fe content. The increase of the conductivity might be attributed to the distortion of the cell lattice, which assisted the migration of the interstitial oxygen ions. The decrease of the conductivity might be caused by the lower concentration of interstitial oxygen ions. The op-timum Fe doping content in lanthanum silicates was 0.6. La10Si5.4Fe0.6O26.7 exhibited the highest ionic conductivity of 2.712×10-2 S/cm at 800 ℃. The dependence of conductivity on oxygen partial pressure p(O2) suggested that the conductivity of La10Si6-xFexO27-x/2 was mainly con-tributed by ionic conductivity.     

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...     

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.     

Energy transfer and 2 μm emission in Tm~(3+)/Ho~(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders

(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders doped with various concentrations of Tm~(3+) and Ho~(3+) were prepared by the citrate method. The standard cubic Y_2O_3 phase can be matched in the Tm~(3+)/Ho~(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2 O_3 nanopowders. The nanopowders exhibit average particle sizes of 40,60, 80 and 100 nm after calcinated at 900,1000,1100 and 1200℃,respectively. The energy transfer from Tm~(3+) to Ho~(3+) and the optimum fluorescence emission around 2 μm were investigated. Results indicate that the emission bands at around 1.86 and 1.95 μm correspond to ~3 F_4→~3 H_6 transition of Tm~(3+) and ~5 I_7→~5 I_8 transition of Ho~(3+), respectively.Better spectral properties were achieved in Tm~(3+)/Ho~(3+) co-doped(Y_(0.87)La_(0.1)Zr_(0.03))_2O_3 nanopowders with the average size of 100 nm obtained at the conditions of the treatment of precursors calcinated at 1200 ℃ for 2 h doped with 1.5 mol% Tm~(3+) and 1 mol% Ho~(3+).     

Influence of composition and sintering temperature on density of structure defects, phase transitions, and properties of magneto-resistive strontium-doped ceramic of manganate-lanthanum perovskites

Ceramic samples of La³ _1?x Sr²⁺ _x MnO^2? ₃ (x = 0, 0.1, 0.15, 0.2, 0.3, 0.4), sintered at different temperatures (1150, 1200, 1350, and 1500 °C) are investigated by means of methods of x-ray diffraction analysis and resistive and magnetic analysis. It is established that the perovskite structure parameter (a) and degree of its rhombohedric $(R\bar 3c)$ distortion (α) both decrease with increasing content of Sr²⁺ in La _1?x Sr _x MnO _3±δ (x = 0–0.4). The metal-semiconductor (T_ms) and ferromagnetic-paramagnetic (T_c) phase transition temperatures and magnetoresistive peak temperature (T_p) all increase, while the activation energy (E_a) decreases. The density of defects in the lattice which contains anion (V^(a)) and cation (in A and B positions) vacancies, average valency of manganese (ω), and tolerance factor (t) also increase. It is shown that with Sr²⁺ doping, charge compensation is achieved by two mechanisms, first, the Mn³⁺ → Mn⁴⁺ transition (～80%), and second, the formation of V^(a) vacancies (～20%), with the contribution of the second mechanism increasing with increasing sintering temperature. With increasing x the magnetoresistive effect decreases at T_p and the lowfield tunneling magnetoresistive effect increases slightly. It is established that the concentration dependence of the intracrystaline peak magnetoresistive effect at T_p is opposite to the concentration dependence of the intercrystalline magnetoresistive effect in the semiconductor region for T ? T_p.     

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].…     

Effect of grain size on thermal stability and oxygen storage capacity of Ce0.17Zr0.73La0.02Nd0.04Y0.04O2 solid solutions

Nanostructured CeO_2-ZrO_2 materials are an irreplaceable constituent in catalytic systems for automobile exhaust purification due to their unique oxygen storage capacity(OSC). However, traditional CeO_2-ZrO_2 materials are easy to sinter at high temperature, which causes a sharp decrease of OSC. In this paper,La~(3+) , Nd~(3+) and Y~(3+) are chosen as dopants for CeO_2-ZrO_2 to improve anti-sintering and OSC properties.The Ce_(0.17) Zr_(0.73) La_(0.02) Nd_(0.04) Y_(0.04) O_2 powders(CZLNY) were prepared by co-precipitation method. The effects of grain sizes with different mixed chlorinated solution concentrations on performances were investigated. X-ray diffraction(XRD) and transmission electron micrograph(TEM) were performed to calculate the grain sizes of CZLNY. The specific surfaces, OSC and redox properties were investigated by N_2 adsorption/desorption and temperature programmed reduction(H2-TPR). The results show that introducing La~(3+) , Nd~(3+) and Y~(3+) into CeO_2-ZrO_2 lattice can improve the stability of phase structure and anti-sintering ability. Moreover, low concentration of mixed chlorinated solution remarkably improves structural and textural properties of CZLNY. Relatively large fresh grain exhibits superior thermal stability and OSC under the condition of being calcined at 800℃ for 3 h. The specific surface and OSC are42.37 m~2/g and 333.13 mmol/g after calcining at 1000℃ for 10 h, respectively. This is owing to the low sintered driving force of large grain and long-range migration energy of large pores during the sintering process, which are beneficial to the stability of structure in CZLNY materials.     

Effects of lanthanum on POD expression and DNA methylation of purple pepper under salt stress

Pepper seedlings were hydroponically cultivated in 0-20 mg/L extraneous lanthanum chloride （La3＋） for different numbers of days to investigate its regulating effects under salt stress. The results showed that, depending on the salt stress of 0.75 g/L, a lower concentration of La3＋ （1.0 rag/L） might result in the lowest death rate, increase POD activity and change the band type of the stem and root on the 8th day. Furthermore, a methylation analysis by the methylation-sensitive amplified polymorphism （MSAP） technique indicated that a lower concentration of La3＋ （1.0 mg/L） triggered the lowest methylation level of 26.1%, of which the hypermethylation events were the primary type of methylation. In addition, the sequencing of 14 differ- entially expressed polymorphic fragments and the subsequent blast search revealed that La3＋ could induce methylation events in salt-tolerance sequences.     

Synthesis and luminescent properties of BaGd2O4:Eu3+ phosphors with highly efficient red-emitting

The BaGd_(2-2 x)Eu_(2 x)O_4(BG, x = 0.01-0.09) phosphors were successfully synthesized via the sol-gel method,and BaY_(2-2 y)Eu_(2 y)O_4(BY, y = 0.005-0.07) phosphors were included for comparison. The pure phase BG phosphors with the ordered CaFe_2 O_4-type structure are obtained by annealing at 1300℃ for5 h. The phosphors with uniform particle size of 120 nm and good dispersion display typical Eu~(3+)emission with the strongest peak at 613 nm(~5 D_0→~7 F_2 transition of Eu3+) under optimal excitation band at 262 nm(CTB band). The presence of Gd~(3+) excitation bands on the PLE spectra monitoring the Eu3+emission directly proves an evidence of Gd~(3+)-Eu~(3+) energy transfer. Owing to the concentration quenching, the optimum content of Eu3+ addition is 5 at%(x = 0.05), and the quenching mechanism is determined to be the exchange reaction between Eu3+. All the BG samples have similar color coordinates and temperature of(0.64 ± 0.02, 0.36 ± 0.01) and 2000 ± 100 K,respectively. The lifetime value of BaGd_(1.9)Eu_(0.1)O_4 for 613 nm is fitted to be 2.19 ± 0.01 ms, and the Eu~(3+) concentration does not change the lifetime significantly. Owing to the Gd~(3+)-Eu~(3+) energy transfer, the luminescent intensity of the BaGd_(1.9)Eu_(0.1)O_4 phosphor is better than BY system. The BG system served as a new type of phosphor is expected to be widely used in lighting and display areas.