Tribological Performance and Tribochemical Mechanism of Lanthanum Dialkyldithiophosphate

Lanthanum dialkyldithiophosphate (LaDDP) was synthesized. Its tribological behavior was evaluated with a four-ball machine. The results show that LaDDP possesses very good antiwear and friction reduction capacities. The boundary film composition, characterized by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy(AES), reveals that the antiwear and friction reduction layer containing metallic La, La2O3, phosphate, sulphate, tribopolmer and lanthanum tribodiffusion layer prevent the rubbing pairs from contacting directly and result in better extreme pressure and antiwear behavior. The microhardness of frictional surface increases by 25%. It indicates that the frictional surface is strengthened by La tribodiffusion layer. The tribological decomposition reactions of LaDDP are simulated through mass spectroscopy. Its tribological mechanism was suggested.     

Synthesis of Mesoporous, Nanocrystalline Lanthanum Phosphate in the Presence of Citric Acid and Stearic Acid

Lanthanum phosphate was prepared in the presence of citric acid and stearic acid under methanolic conditions at pH 4.5 and pH 7, respectively. The samples obtained were intensively characterized using X-ray diffraction, nitrogen adsorption-desorption isotherm study, transmission electron microscopy （TEM）, thermal gravimetric and differential thermal analysis, and Fourier transform infrared （FTIR） analysis . The as-synthesized samples prepared at pH 4.5 showed lamellar mesostruroned form with high crystallinity. Results showed that the pore size and pore volume changed when the materials were prepared under different pH conditions. Morphology of the samples was observed by using TEM, which showed that the samples possessed relatively small particles closely packed together. The as-synthesized samples were investigated using FTIR, and the mesopore formation mechanism was discussed.     

十二烷硫基硼酸铈的合成及摩擦学行为研究

合成了油溶性化合物十二烷硫基硼酸铈(简称CeDMB)，并用作润滑油添加剂。采用四球摩擦试验机和环—块试验机评价了其抗磨减摩性能。结果表明，十二烷硫基硼酸铈使HVI500基础油的抗磨性能得到明显改善，承载能力明显提高，摩擦系数明显降低。扫描电子显微镜(SEM)观察证实磨斑表面含有沉积物膜，结合X—射线光电子能谱(XPS)分析，可以推断添加剂在摩擦过程中发生摩擦化学反应，生成的Ce2O3、CeO2和B2O3沉积在摩擦副表面，形成润滑膜，从而改善其抗磨减摩性能。     

Toxic Effects of Lanthanum, Cerium, Chromium and Zinc on Potamogeton Malaianus

iththerapiddevelopmentofrareearthindustryandextensiveapplicationofrareearthinagriculture ,agreatmanyofrareearthelements (REEs)werere leasedintoenvironment ,especiallywaterenviron ment ,andtheconsequentseriousenvironmentpollu tionhasattractedpeople′satten…     

Influence of Lanthanum on Tribological Properties and Microstructure of Laser Clad B ＋ Fe ＋ Si Composite Coatings

The effects of rare earth ferrosilicon on the microstructure and anti-wear properties of laser-clad Fe-based alloy coating were investigated. The composition of Fe, B4C and rare earth ferrosillcon powders with different contents of lanthanum were clad onto a 45 # carbon steel substrate. Microstructural features, chemical compositions, phase structure,hardness, friction and wear properties by scanning electron microscopy (SEM), X-ray photoelectron microscopy (XPS),hardness tester, block-on-ring friction and wear tester of the clad coating were determined. Experimental results show that the friction coefficient of the clad coating doped with rare earth ferrosilicon is reduced while the wear resistance of clad coating doped with rare earth ferrosilicon is enhanced. When the content of lanthanum increases to 1.92%, the clad coating shows the best anti-wear ability, and as the content of lanthanum exceeds 1.92%, the wear weight loss increases quickly. The rare earth ferrosilicon to be doped in the clad coatings helps to disperse the boride phase (Fe2B, FeB, B4C)particles and refine the grain of boride phase. The enhancement of clad coating‘s wear resistance is due to the existence of dispersed boride phases.     

Low Temperature Phase Transition Behavior of Ca-Doped Lanthanum Chromites

Phase transition of LaCrO3 and doped-LaCrO3 was studied by DSC, TG and XRD, and thermal expansion during the transition was analyzed. It is found that phase transition of LaCrO3 begins at about 240℃ and ends at about 265 ℃. Temperatures of phase transition rise obviously with increasing Ca^2＋ content. The transition of LaCrO3 and Ca-doped LaCrO3 from orthorhombic to rhombohedral is accompanied with endothermic reaction. No obvious change occurs in mass, but remarkable shrinkage occurs during phase transition.     

Subchronic Toxicity of Lanthanum Nitrate on Liver in Rats

ｌｏｎｇｗｉｔｈｔｈｅｗｉｄｅｓｐｒｅａｄａｐｐｌｉｃａｔｉｏｎｏｆｔｈｅＲＥＥｉｎａｇｒｉｃｕｌｔｕｒｅ ,ａｎｉｍａｌｈｕｓｂａｎｄａｒｙａｎｄｍｅｄｉｃｉｎｅｏｆｏｕｒｃｏｕｎｔｒｙ ,ｔｈｅｉｎｃｒｅａｓｉｎｇｃｏｎｃｅｒｎｗｉｔｈｔｈｅＲＥＥｃａｌｌｓｆｏｒｔｈｅｘｔｅｎｓｉｖｅｓｔｕｄｉｅｓｏｎｔｈｅｉｒｍｅｔａｂｏｌｉｃａｃｃｕｍｕｌａｔｉｏｎａｎｄｂｉ ｏｌｏｇｉｃａｌｅｆｆｅｃｔｓ .ＴｈａｔｓｏｍｅｃｅｌｌｓｃａｎｔａｋｅｉｎＲＥＥｂｙｍｅａｎｓｏｆｐｈａｇｏｃｙｔｏｓｉｓｏｒｐｉ…     

Effects of Lanthanum Ion and Its Complexes on Permeability of Pollen Plasmalemma and Pollen Germination

Effects of Lanthanum Ion and Its Complexes on Permeability of Pollen Plasmalemma and Pollen Germination     

Corrosion Inhibition Synergism between Lanthanum （ Ⅲ ） Ion and 8-Hydroxyquinoline for Zinc in Hydrochloric Acid

The effects of La^3 ion and chelate reagent 8-hydroxyquinoline on the corrosion rate of zinc in hydrochloric acid were investigated by using weight loss method and electrochemical method. It is found that in a specific concentration range of La^3 ion and 8-hydroxyquinoline, the obvious corrosion inhibition synergism is obtained.The mechanism of corrosion inhibition synergism was discussed on basis of adsorption theory.     

Effects of Lanthanum on Hydrolytic Enzyme Activities in Red Soil

The effects of La on some hydrolytic enzyme activities in red soil were studied in incubation and pet 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 pet 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 eivps.     

Mechanochemical Reaction of Lanthanum Carbonate with Sodium Hydroxide and Preparation of Lanthanum Oxide Nanoparticle

Ｔｈｅｉｍｐｏｒｔａｎｃｅｏｆｎａｎｏｓｉｚｅｄｒａｒｅｅａｒｔｈｏｘｉｄｅｐｏｗｄｅｒｓｉｎｖａｒｉｏｕｓｔｅｃｈｎｉｃａｌａｐｐｌｉｃａｔｉｏｎｓｍａｋｅｓｔｈｅｉｒｐｒｅｐａｒａｔｉｏｎｔｅｃｈｎｏｌｏｇｙａｎｉｎｔｅｒｅｓｔ ｉｎｇｓｕｂｊｅｃｔｆｏｒｒｅｓｅａｒｃｈｗｏｒｋ[1 ] .Ｏｖｅｒｔｈｅｐａｓｔｄｅｃａｄｅｓ,ｍａｎｙｐｒｅｐａｒａｔｉｏｎｍｅｔｈｏｄｓｏｆｎａｎｏ ｓｉｚｅｄｒａｒｅｅａｒｔｈｏｘｉｄｅｓｈａｖｅｂｅｅｎｄｅｖｅｌｏｐｅｄ ,ｉｎｃｌｕｄｉｎｇｐｈｙｓｉｃａｌａｎｄ…     

Existing Forms of Lanthanum in Purity Steels

Adding lanthanum to carbon-manganese purity steel, the existing forms of lanthanum were investigated. The results show that enrichment on grain boundary and solid solution in cementite are two kinds of important existing forms of lanthanum relating to micro-alloyed action. As a result of enrichment of lanthanum, the concentration of lanthanum aggregated on somewhere of grain boundary reaches as high as tens of times of its average content although the average content is very low. In addition, lanthanum atoms can replace partial Fe atoms that constitute cementite to form alloyed cementite, the solid solution amount of lanthanum in alloyed cementite increases as the increase of its average content in purity steel.     

Structure and Growth Mechanism of Lanthanum Chromate

The unit cell of lanthanum chromate was constructed by calculating equivalent points. By means of calculation of the hole octahedrally surrounded by O^2- ions, it was considered that the sintered property of lanthanu,n chromate and the stability of Cr - O octahedron might be promoted by mixing a little Ca^2 ions. The growth mechanism was discussed in terms of structural ledge observed by SEM, the surfaces of the structural ledges parallel to (001), (010) and (110)planes, respectively. The misfit between (110) and (001) planes is only 0.0021 on common atomic plane, and the interconnection of the structured ledge may occur during crystal growth.     

Thermodynamic Assessment of Interaction Relation between Lanthanum and Constituent Elements in Sn-Pb Alloy

Ｂｙａｄｄｉｎｇｔｒａｃｅａｍｏｕｎｔｏｆｌａｎｔｈａｎｕｍ(0 0 2 4% ) ,ｔｈｅｍｉｃｒｏｓｔｒｕｃｔｕｒｅｏｆｔｒａｄｉｔｉｏｎａｌＳｎ6 0 Ｐｂ40ｓｏｌｄｅｒａｌｌｏｙｉｓｈｏｍｏｇｅｎｉｚｅｄ ,ｔｈａｔｉｓ ,ｔｈｅｃｏａｒｓｅＳｎ ｒｉｃｈｈａｌｏｗｈｉｃｈｓｕｒｒｏｕｎｄｓｔｈｅｐｒｉｍａｒｙＰｂ ｒｉｃｈｐｈａｓｅｉｓｄｅｐｒｅｓｓｅｄｏｂｖｉｏｕｓｌｙ .Ａｓａｒｅｓｕｌｔ,ｔｈｅｈｉｇｈ ｔｅｍｐｅｒａｔｕｒｅｔｅｎｓｉｌｅｓｔｒｅｎｇｔｈｏｆＳｎ6 0 Ｐｂ40ｓｏｌｄｅｒａｌｌｏｙｉｎｃｒ…     

Preparation of Lanthanum Nickel Oxide-Coated Ni Sheet Anodes and Their Application to Electrolytic Production of (CF3)3N in (CH3)4NF·4.0HF Melt

A new process for electrolytic production of a perfluorinated compound, (CF3)3N, using lanthanum nickel oxide-coated Ni sheet anode in the (CH3)4NF·4.0HF melt at room temperature, was developed. Thin films of the lanthanum nickel oxides were prepared on Ni sheets by sol-gel coating method using polyvinlylpyrrolidone(PVP). The main components of the thin films were La2O3, LaNiO3, and La2NiO4 at 500, 750 and 1000 ℃, respectively. The anode performance in the (CH3)4NF·4.0HF melt depends greatly on the main component of the thin film, and the LaNiO3-coated Ni sheet anode gives the best anode performance. The potential of LaNiO3-coated Ni sheet anode remains constant at 5.9 V during electrolysis at 20 mA·cm-2 in the (CH3)4NF·4.0HF melt for 100 h. This is because LaNiO3 and NiF3 and/or Ni2F5, the latter of which was formed during electrolysis, in the film give a high electronic conductivity to the surface film during electrolysis. The maximum mole fraction of (CF3)3N (21.4%) was obtained at 20 mA·cm-2 in (CH3)4NF·4.0HF melt using the LaNiO3-coated Ni sheet.     

Synthesis and Characterization of Lanthanum Complexes with Amino Acid Schiff Base

Ｉｎｔｈｅｌｉｖｉｎｇｂｅｉｎｇｓ ,ｃａｌｃｉｕｍｉｏｎｐｏｓｓｅｓｓ ｅｓｍａｎｙｋｉｎｄｓｏｆｉｍｐｏｒｔａｎｔｂｉｏｌｏｇｉｃａｌｆｕｎｃｔｉｏｎ .Ｔｈｅｒａｄｉｕｓａｎｄｔｈｅｃｏｏｒｄｉｎａｔｅａｃｔｉｏｎｏｆｌａｎ ｔｈａｎｕｍｉｏｎａｒｅｓｉｍｉｌａｒｔｏｔｈａｔｏｆｃａｌｃｉｕｍｉｏｎ .Ｃｏｎｓｅｑｕｅｎｔｌｙ ,ｌａｎｔｈａｎｕｍｉｏｎ ,ｗｈｉｃｈｅｎｔｅｒｓｔｈｅｂｏｄｙ ,ｗｉｌｌｒｅｐｌａｃｅｃａｌｃｉｕｍｉｏｎａｎｄｓｈｏｗａｓｅｒｉｅｓｏｆｂｉｏｌｏｇｉｃａｌｅｆｆｅｃｔｓ…     

Effect of Lanthanum on Plants under Supplementary Ultraviolet-B Radiation： Effect of Lanthanum on Flavonoid Contents in Soybean Seedlings Exposed to Supplementary Ultraviolet-B Radiation

The effects of solar ultraviolet-B (UV-B,280 ~320 nm) radiation on plants have been studiedintens-ively over the last two decades ,associated withthe re-search onthe biological i mpacts of stratospheric ozonedepletion .There are a large number of reports aboutthe effects of UV-B radiation on crops[1 ~5].Flavonoidcompounds , as secondary metabolites are consideredto play a major role in protecting plants from UV-Bdamage[6].These flavonoids generally absorbthe lightinthe region of 280 ~320 n…     

Effects of Lanthanum and Cerium on Acid Phosphatase Activities in Two Soils

To evaluate the security of using thulium, comparision between effects of La and those of Ce on acidic phosphatase activities in red soil and yellow soil in Zhejiang district was studied under conditions of ambient temperature and humidity. Results show that the acid phosphatase from different soil respondes to La and Ce differently. The activity of acid phosphatase in soil 1 declines with the increase of the concentration of La and Ce. The maximum inhibitory ratio of La and Ce reaches 69.8% and 71.0% respectively. But La and Ce have stimulative effect on the activity of acid phosphatase in soil 2.Under the effect of same concentration of the thulium, the acid phosphatase in two soils increases with the extending of culture time.     

Behavior and Mechanisms of Deformation in Intermetallic Compound Al_(66) Mn_9Ti_(25) La

Ｂｅｃａｕｓｅｔｈｅｂｉｎａｒｙｉｎｔｅｒｍｅｔａｌｌｉｃｃｏｍ ｐｏｕｎｄＡｌ3ＴｉｈａｓｔｈｅｔｅｔｒａｇｏｎａｌＤＯ2 2 ｓｔｒｕｃｔｕｒｅｗｉｔｈｔｈｅｌｏｗｓｙｍｍｅｔｒｙ ,ｉｔｉｓｅｘｔｒｅｍｅｌｙｂｒｉｔｔｌｅ .ＢｙｒｅｐｌａｃｉｎｇｏｆａｐａｒｔｏｆＡｌｗｉｔｈＭｎ ,ｉｎｔｅｒ ｍｅｔａｌｌｉｃｃｏｍｐｏｕｎｄＡｌ66Ｍｎ9Ｔｉ2 5 ｗｉｔｈｔｈｅｈｉｇｈｅｒｓｙｍｍｅｔｒｙＬ1 2 ｓｔｒｕｃｔｕｒｅｃａｎｂｅｏｂｔａｉｎｅｄ .Ａｓａｒｅｓｕｌｔ,ａｎｉｍｐｒｏｖｅｍｅｎｔｉｎｐｒｏｐｅｒｔ…     

Synthesis, Characterization and Antitumor Activity of Lanthanum(Ⅲ) Complex with Demethylcantharidate

A novel complex of lanthanum(Ⅲ) with demethylcantharidate group (DCA), Na[La(DCA)2(H2O)], was synthesized in aqueous solution and characterized by elemental analysis, molar conductance, IR, UV, 1H-NMR spectra and TG-DTA. The results suggest that lanthanum ion is seven-coordinated. Six oxygen atoms are from carboxyl groups and cyclic ethers of two DCA ligand, and on oxygen is from a H2O. The antitumor activities of the complex against HL-60 human leukemia, BGC-823 human gastric carcinoma, Bel-7402 human hepatic carcinoma, Hela human cervical carcinoma were investigated with MTT or SRB assays. Na[La(DCA)2(H2O)] exhibits stronger inhibition against certain kinds of cancer cells than Na2DCA in vitro.