Toxicological effects of rare earth yttrium on wheat seedlings（Triticum aestivum）

This study examined the biochemical responses of wheat（Triticum aestivum） to the stress of rare earth yttrium（Y） and showed that 25–100 mg/kg Y treatments evidently increased the biomass（root mass,shoot mass and leaf mass）,accompanied by a significant（p0.05） increase in the chlorophyll（CHL） content in wheat leaves.Increased malondialdehyde（MDA） levels were detected in wheat shoots（stem and leaf） and roots too,indicating the presence of poisoning active oxygen species（AOS）.The MDA content in wheat roots increased with the augmentation of Y concentration.These results indicated that there was a dose-dependent effect of Y on the changes of MDA content in wheat roots.Although the activities of superoxide dismutases（SOD）,peroxidases（POD） and catalases（CAT） in wheat shoots and roots irregularly fluctuated with the increase in Y concentration,25–100 mg/kg Y significantly（p0.01） increased the activities of SOD and POD.In general,the dose-dependent effects of Y on the activity of antioxidant enzymes were insignificant.Our data also indicated that the increase in SOD and POD activities could be used as a good biomarker for the stress induced by low concentrations of Y.     

Influence of partial substitution of cerium for lanthanum on magnetocaloric properties of La_(1–x)Ce_xFe_(11.44)Si_(1.56) and their hydrides

The structure and magnetocaloric properties of La1–xCexFe11.44Si1.56 and their hydrides La1–xCexFe11.44Si1.56Hy（x=0, 0.1, 0.2, 0.3, 0.4） were investigated.The samples crystallized mainly in the cubic Na Zn13-type structure with a small amount of α-Fe phase as impurity.The lattice constants and Curie temperature presented the same change tendency with increasing of Ce content.For the hydrides, the influence of Ce content on lattice constants was weakened and the values of H concentration y were approximate to be 1.56.The La1–xCexFe11.44Si1.56 compounds exhibited large values of isothermal entropy change –ΔSm around the Curie temperature TC under a low magnetic field change of 1.5 T.The value of –ΔSm increased and then decreased with increasing Ce content, reached the maximum, 26.07 J/kg·K for x=0.3.TC increased up to the vicinity of room temperature by hydrogen absorption for the Ce substituted compounds, but TC only slightly decreased with increasing Ce content.The first-order metamagnetic transition was still kept in the hydrides and the maximum values of –ΔSm were lower than those of the La1–xCexFe11.44Si1.56 compounds, but still remained large values, about 10.5 J/kg K under a magnetic field change of 1.5 T.The values of –ΔSm were nearly independent of the Ce content and did not increase with increasing x for the hydrides.The La1–xCexFe11.44Si1.56Hy（x=0–0.4） hydrides exhibited large magnetic entropy changes, small hysteresis loss and effective refrigerant capacity covered the room temperature range from 305 to 317 K.These hydrides are very useful for the magnetic refrigeration applications near room temperature under low magnetic field change.     

Control effect of lanthanum against plant disease

Effect of La on emergence, growth and development of Isatis indigotica Fort. and Festuca arundinacea seedlings was researched by pot experiments of inoculating Rhizoctonia solani and with the mixture ofRhizoctonia solani and Fusarium solani in disinfected soil after the seeds were soaked in the solution with different concentrations of La^3＋. The results indicated that infection rate decreased and there were significant disease controlling effects on seed rot, bud rot and root rot caused by pathogenic fungi when the seeds were soaked by La^3＋. Thus, the rates of emergence of Isatis indigotica Fort. and turfgrass Festuca arundinacea were increased, When La^3＋ concentration was in a proper range, the growth and development of plant seed/ings were promoted. Spraying La on rice plants showed a significant controling effect on Rhizoctonia solani. Furthermore, the EC50 of La^3＋performed 128.7 and 128.1 mg/L at 1 and 7 d after spraying La in rice plants, respectively. The EC50 of La^3＋ performed in vivo （in rice plant） was lower than that in vitro （171.9 mg/L）.     

Effects of lanthanum addition on microstructure and mechanical properties of as-cast pure copper

As-cast Cu-La alloys with La contents in the range of 0–0.32 wt.% were fabricated by vacuum melting method. The effects of La on microstructure and mechanical properties of as-cast pure copper were investigated using optical microscopy(OM), scanning electronic microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and tensile test. The results showed that La had obvious effects on the solidification microstructure and the grain refinement of as-cast pure copper. With the increase of La content, the ultimate tensile strength, the yield strength and the microhardness increased gradually, but the elongation increased first and then decreased while La content exceeded 0.089 wt.%. The improvement of mechanical properties was attributed to the effect of grain refinement strengthening, solid solution strengthening, second phase strengthening and purifying. However, excessive adding La would deteriorate the elongation owing to the excessive Cu6 La phases.     

The glucosinolate regulation in plant: A new view on lanthanum stimulating the growth of plant

The harmful effect of low-concentration lanthanum [La(Ⅲ)] on plants was investigated by choosing horseradish as a representative of plants and using the methods of physics, analytical chemistry and biology. The results show that the genetic expressions related to glucosinolates(GLS, the marker of plant resisting harmful effects) synthesis are significantly increased after the endocytosis in leaf cells is initiated by low-concentrations La(Ⅲ). Consequently, the activities in the key enzymes for catalyzing the GLS synthesis are promoted. Meanwhile, the contents of the precursors and substrates in GLS synthesis are increased. All the above changes accelerate the GLS synthesis and result in the maximum increase in GLS content by 14%. Finally, the uptake of nutrient elements in horseradish is enhanced, and the yield of horseradish is maximally increased by 25%. Therefore, low-concentration La(Ⅲ) is harmful to plants, and plants can promote growth to resist the harmful effects of low-concentration La(Ⅲ) by regulating GLS content. The results show a new insight into how rare earth elements stimulate plant growth, and provide a reference for the risk assessment of rare earth elements.     

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.     

Induction of Volatile Organic Compounds in Leaves of Lycopersicon Esculentum by Nd^3＋

The effects of Nd^3＋ on the quality and quantity of volatile organic compounds （VOCs） in the leaves of Lycopersicon esculentum were studied. The results demonstrate that Nd^3＋ can increase the total amount of VOC by 75% after treatment for 120 h, as compared with the control. Phyto-oxylipins, terpenoids and aromatic compounds were increased by 73%, 38% and 21%, respectively. （E）-2-hexenal, the most abundant constituent is increased by 74%, β- phellandrene and α-caryophyllene in terpenoids,     

Influence of welding-flux moisture on welding quality

A high hydrogen content in weld produces hydrogen embrittlement,welding cold cracks,and even blowholes,which seriously affect joint performance and welding quality.Submerged-arc-welding flux has a great influence on the hydrogen content of the final weld.To simulate different flux storage circumstances and prewelding treatments,the effects of different welding-flux states on the welding quality and hydrogen content in weld were compared,using moisture content determination test and hydrogen content in deposited metal determination test.The test results reveal that to ensure the quality of welding,it is necessary to strictly control the storage of welding flux and procedures followed when using it.     

Ce1–xSmxO2–δ-attapulgite nanocomposites：synthesis via simple microwave approach and investigation of its catalytic activity

Ce1–x Smx O2–δ-attapulgite（ATP） nanocomposites were successfully prepared via a facile microwave approach.This was a facile and rapid process requiring only low power of microwave irradiation（160 W）.The catalytic performance of the Ce1–x Smx O2–δ-ATP nanocomposites with different Sm contents for degradation of methylene blue（MB） was systematically evaluated.The Ce1–x Smx O2–δ-ATP nanocomposites showed enhanced catalytic activities compared with pure CeO2/ATP.Specifically,the catalytic activities of Ce1–x Smx O2–δ-ATP nanocomposites increased with increase in Sm content from x=0.0 to 0.3.The introduction of an optimal amount of Sm3＋into CeO2 contributed to the formation of structure defects and electronic defects in the oxide lattice,which could increase concentration of oxygen vacancies.However,further increasing Sm content to x=0.4 induced the formation of more agglomerates,leading to decreased catalytic activity.It was believed that this facile,rapid microwave-assisted strategy was scalable and could be applied to synthesize other nanocomposites for different applications.     

Effect of substitution of aluminum for nickel on electrochemical properties of La_(0.75)Mg_(0.25)Ni_(3.5–x)Co_(0.2)Al_x hydrogen storage alloys

La0.75Mg0.25Ni3.5–xCo0.2Alx (x=0–0.09) hydrogen storage alloys were prepared by induction melting and effect of Al substitution for Ni on phase constitution and electrochemical property was investigated.With the substitution of Al for Ni,LaNi5 and LaNi2 phases occurred and (La,Mg)2(Ni,Co,Al)7 phase with hexagonal Ce2Ni7-type structure replaced (La,Mg)2(Ni,Co)7 phase.The cell volumes of LaNi5 and (La,Mg)2(Ni,Co,Al)7 main phases increased with increasing Al content.Some electrochemical properties and kinetic parameters of the alloys,including discharge capacity,high rate discharge ability (HRD),loss angle (ψ),exchange current density (I0) and limiting current density (IL),decreased with increasing amount of substitution of Al for Ni.Substitution of Al for Ni could be favorable for positive shift in corrosion potential of the alloy electrode,and prolonged cyclic lifetime of La0.75Mg0.25Ni3.5–xCo0.2Alx (x=0–0.09) alloy electrodes.     

Sealing Glass of Barium-Calcium-Aluminosilicate System for Solid Oxide Fuel Cells

Glass-ceramic materials were developed as a sealant in the solid oxide fuel cell （SOFC） in the temperature range of 800 -850 ℃. The glass materials were based on the glass and glass-ceramic in the BaO-CaO-Al2O3-SiO2-La2O3-B2O3 system. The thermal expansion coefficient （TEC） decreased with lower Ba^2＋ content and higher Ca^2＋ content, but the glass transition temperature and crystallization temperature increased greatly with an increase in Ca^2＋ content and a decrease in Ba^2＋ content, when the other components in the sealant were invariable. The TEC of the sealant with Ba^2＋ content of 25.4% was 10.8 × 10^-6 K^- 1（temperature range from 25 to 850℃）, and its softening temperature was 950 ℃. The TEC of the sealant accorded well with that of La0.9Sr0.1Ga0.5Mg0.2o3- 6（LSGM） with a mismatch of only 3%. The sealant had superior stability and compatibility with the LSGM electrolyte during the process of operation in SOFC. The weight loss of the sealant with Ba^2＋ content of 25.4% was approfimately zero after heat-treated at 800℃ for 500 h in H2 and O2 atmosphere, respectively.     

Characterization of A-site excessive perovskite La0.7-xSmx＋0.02Ca0.3CrO3-δ

La0.7-xSmx+0.02Ca0.3CrO3-δ(0≤x≤0.4) powders with A-site excessive perovskite structure were synthesized by auto-ignition process and characterized. X-ray diffraction (XRD) patterns of samples after sintering at 1400℃ for 4 h were indexed as tetragonal structure. The relative densities were all above 96% although decreased slightly with the increasing content of samarium, indicating that the excessive A-site element was helpful to enhance their sinterability. Conductivities of the specimens in air increased with increasing content of samar-ium. The conductivity of La0.6Sm0.12Ca0.3CrO3-δ was 33.6 S/cm in air at 700 ℃ which was about 1.7 times as high as that of La0.7Ca0.3CrO3-δ (20.1 S/cm). Average thermal expansion coefficients (TECS) of the specimens increased from 11.06×10-6 to 12.72×10-6 K-1 when x in-creased from 0 to 0.4, and they were close to that of Y doped ZrO2 (YSZ). La0.7-xSmx+0.02Ca0.3CrO<3-δ>(0.1≤x≤0.3) were good choices for in-termediate temperature solid oxide fuel cells (IT-SOFCs) interconnect materials.     

Effect of annealing treatment on microstructure and mechanical properties of Al/Ni multilayer composites during accumulative roll bonding (ARB) process

Al/Ni multilayer composites are produced by accumulative roll bonding process and then annealed with different temperatures and time.Macroscopic images,microstructure and mechanical properties of Al/Ni multilayer composites are investigated.As for the macroscopic images,although there was an edge crack along the rolling direction at the third pass,the defect of composites was not serious and the forming quality of composites was relatively good.The yield strength and elongation of Al/Ni multilayer composites are improved after the annealing treatment;however,with the increase in annealing temperature and time,the yield strength and ciongation of Al/Ni multilayer composites are decreased.During the process of annealing treatment,aluminum atoms diffuse in the way of vacancy diffusion,which results in the formation of Al3Ni intermetallic phase at Al/Ni interface and Kirkendall void in the aluminum side.The content of Al3Ni intermetallic phase and Kirkenckill void would increase with the increase in annealing temperature and time.     

Propane catalytic cracking on pretreated La-ZSM-5 zeolite during calcination for light olefins production

The purpose of this study was to increase light olefins yield and selectivity in catalytic cracking of propane. Pretreatment of ZSM-5 zeolite was performed during calcination. First, lanthanum was loaded on the catalyst by wet impregnation method and then the effect of parameters, such as temperature(400–800 oC), time(120–480 min) and type of stream, on La-ZSM-5 zeolite was examined during calcination using central composite design(CCD) method. Based on the proposed models, the optimized condition for maximizing selectivity of light olefins for air stream was 680 oC and 310 min and for the nitrogen stream was 735 oC and 173 min that under these conditions, selectivity amount increased 24% for nitrogen stream and 19% for air stream as compared with H-ZSM-5 catalyst. The synthesized catalysts were characterized by X-ray diffraction(XRD) and temperature-programmed desorption(TPD) techniques. According to the results of NH_3-TPD, as the temperature increased, the number of strong acid sites(specially Bronsted acid sites) reduced and resulted in increased production of light olefins as well as catalyst stability. Accordingly, stability of the samples calcined with nitrogen stream was higher than the samples calcined with the air stream.     

Effects of Heat Treatment Process Parameters on Microstructure and Mechanical Properties of DP440Cold Rolled Strip

In order to optimize the production process, improve the production efficiency and accelerate the development and application of the domestic dual-phase steel, the effects of heat treatment process parameters on microstructure and mechanical properties of DP440 cold rolled strip were studied by the CAS-300 simulated continuous annealing equipment. When the heating rate increased from 5 to 100 ℃/s, both the tensile strength and yield strength increased because of the decreased grain size. When the intercritical annealing temperature increased from 780 to 850 ℃, the martensite content decreased so that the tensile strength decreased first, then increased, and the yield strength increased. When the rapid cooling rate increased from 25 to 100 ℃/s, because the martensite content increased, the tensile strength increased, while the yield strength decreased. When the overaging temperature increased from 260 to 400 ℃, the tensile strength decreased, while the yield strength increased. When the overaging time increased from 240 to 480 s, the tensile strength decreased a little, while the yield strength increased a little.     

Improved electrochemical kinetic performances of La-Mg-Ni-based hydrogen storage alloys with lanthanum partially substituted by yttrium

Yttrium(Y) has been used as the partial substitution element for lanthanum(La) to improve the electrochemical kinetic performances of La-Mg-Ni-based hydrogen storage alloys. La0.80–xYxMg0.20Ni2.85Mn0.10Co0.55Al0.10(x=0.00, 0.05 and 0.10) alloys were prepared by the inductive melting technique. The alloys were composed of La Ni5 and(La,Mg)2Ni7 phases, the introduction of Y promoted the formation of(La,Mg)2Ni7 phase, and thus the Y-substituted alloy electrodes exhibited higher discharge capacities. Y substitution was also found to be effective to improve the discharge kinetics of the alloy electrodes. When the Y content x increased from 0.00 to 0.10, the high-rate dischargeability of the alloy electrodes at a discharge current density of 1800 m A/g(HRD1800) increased from 23.6% to 39.7% at room temperature. In addition, the measured HRD1800 showed a linear dependence on both the exchange current density and the hydrogen diffusion coefficient at different temperatures, respectively.     

Flow Uniformity of Roller-Type Quenching Machine

 Abstract: Three dimensional finite element flow field model of spraying pipe of roller-type quenching machine is built. The flow field under different structural parameters is computed. After grouping the nozzles, the spraying uniformity is analyzed under different water inlet pipe diameter, different water inlet pipe distance, nozzle diameter, nozzle distance. And the spraying intensity absolute deviation and relative deviation are computed under different conditions. The effect rule of different structural parameters to cooling uniformity is obtained. The results provide theoretical support for improving production quality and optimizing cooling device design.     

Effects of Cobalt Content and Preparation on Electrochemical Capacity of AB5-Type Hydrogen Storage Alloys at Different Temperature

The effects of Co as a substituent for Ni on microstructure and electrochemical capacity of hydrogen storage alloys MI(NiCoMnAl)5.4 at -30～ 80 ℃, in which the content of Co was 0, 1.31%, 2.63%, 3.94%, 5.25%, and 6.56% (mass fraction), respectively, were reported. All of the alloys were prepared by vacuum induction melting followed by melt-spinning. It is found that the electrochemical capacity of alloys at different temperature depends upon the compositions and preparation methods. The electrochemical capacity of alloys increases at higher temperature (40 ～ 80 ℃ )and decreases at lower temperature ( - 30 ～ 0 ℃ ) with an increasing cobalt content. With an increasing temperature,melt-spinning is more favorable for improved capacity of the alloys than casting. Analyses of the charging/discharging potential curves illustrate that higher cobalt content and melt-spinning techniques are more effective to increase the capacity at higher temperature because of the higher hydrogen evolution potential. On the contrary, the capacity of alloys at lower temperature can be increased by decreasing cobalt content and casting, which is ascribed to higher hydrogen evolution potential and delayed hydrogen evolution reaction, as well as reduced potential drop in the charging/discharging process.XRD patterns confirm that all of the specimens present a single hexagonal CaCu5-type structure and an increased lattice parameters with increasing Co content. The FWHM of the main peak of melt-spun ribbons reduces because of more homogeneous composition and less lattice strain defects.     

Biosorption of La^3＋ and Ce^3＋ by Agrobacterium sp.HN1

The Agrobacterium sp.HN1 was isolated from the soil and used to adsorb rare earth ions La3+ and Ce3+.The results showed that the pretreatments of Agrobacterium sp.HN1 did not enhance the adsorption of La3+ and Ce3+.The pH,temperature,time and bacterial age affected the dynamics of adsorption of La3+ and Ce3+.The optimum adsorption conditions for Agrobacterium sp.HN1 were as follows:15 mg/L La3+ of initial concentration,10 mg/L Ce3+,300 mg/L(dry wt.cell) biomass for sorption,6.8 pH,30 oC temperature,150 r/min rotational speed,2 h adsorption time and 28 h bacterial age.The adsorption kinetics of La3+ and Ce3+ for Agrobacterium sp.HN1 followed the pseudo-second order equation.     

Lanthanum Modified Ni/y-Al2O3 Catalysts for Partial Oxidation of Methane

La modified Ni/T-Al2O3 catalysts prepared by co-precipitation method using NaOH-Na2CO3 as a precipitator show high activity and selectivity for the partial oxidation of methane （POM）. Meanwhile, the addition of La is beneficial for the formation of an active component and stability of support. We investigated some factors including calcining temperature, nickel content, and space velocity, which turned out to have a strong influence on catalytic activity and selectivity. By XRD and TPR, it is concluded that Ni^0 reduced from amorphous NiAl2O4 is the major active component for POM.