Preparation and Electrorheological Property of NaNO3-Doped Y2O3 Material

Theelectrorheological(ER)fluidisasuspension ofpolarizablesolidparticlesdispersedinanon con ductingliquid,exhibitingdrasticandreversible changeinrheologicalpropertieswhenanexternalelec tricfieldisappliedviaorderingofthemicrostructure intoparticulatecolumns[1].Thisrapidandreversibleresponsehaspotentialapplicationinmanyelectrically controlledmechanicaldeviceswhichtransformelectri calenergyintomechanicalenergy,suchasclutches,valves,dampingdevices,andsoon[2,3].However,ERfluidhasnotbeenutilizedlarg…     

Thickness Effect on Electronic Transport in Single Crystal La0.67 Ca0.33 MnO3 Thin Films

Lattice strain in thin films induced by film-sub-strate mismatchis one source for variant magnetic andresistive behaviors especiallyfor the manganite perovs-kites for which the lattice effects are wellestablished[1~5].It has been also reported that low-fi…     

Effect of Y2O3 Content on Microstructure of Gradient Bioceramic Composite Coating Produced by Wide-Band Laser Cladding

Hydroxyapatite (HA) ,a kind of bioactive materi-al , has wide application prospect in hard tissue re-placemen and repairment due to its si milar chemicalcomposition and crystallographic structure to that ofbone mineral[1 ,2]. Since HA has lowstrength (50 …     

Synthesis of YAG∶Ce~(3+) Phosphor by Polyacrylamide Gel Method and Promoting Action of α-Al_2O_3 Seed Crystal on Phase Formation

Cerium activatedyttriumaluminumgarnet Y3Al5O12(YAG∶Ce3+)isknownasanefficientphos phor,whichhasstrongyellowluminescencewhenex citedbybluephotons.Therefore,YAG∶Ceisideally suitedforluminescenceconversionofbluelightemit tingdiodes[1,2],andusedintheassemblingofwhite lightemittingdiode(wLED),sinceblueandyellow arecomplementarycolors.Suchdiodesarenowcom merciallyavailable[2].HighluminancewhiteLEDhas beenarousedattentionaroundworldduetoitslighting withnohydrargyrum,highefficiencyandlonglife.…     

Preparation and Characterization of Red Luminescent Ca_(0.8)Zn_(0.2)TiO_3∶ Pr~(3+), Na~+ Nanophosphor

Pr dopedalkalineearthmetaltitanateswithper ovskitestructurehaverecentlybeenthesubjectof manyinvestigations.Thisisbecauseoftheirhigh chemicalstability,strongandsharpredemission,and longafterglowluminescence[1～13].CaTiO3∶Pr3+,asa relativelynewluminescencematerialofthatcategory,andexhibitsredcathodoluminescencelocatedatthe CIEcoordinate[8]ofx=0.680andy=0.311,very closeto“idealred”ofNTSC(NationalTelevision StandardsCommittee).Inaddition,itisapromising redlongpersistencephosphor,whichmayp…     

Preparation and Upconversion Luminescence of Y_3Al_5O_(12):Yb~(3+),Er~(3+)Transparent Ceramics

Crystalline Y3Al5O12(YAG) exists in the cubicform,having a garnet structure[1 ,2],and has excellentchemical stability ,good optical and high temperaturecreep chemical stability[3 ~5]. YAG single crystal hasdrawn considerable attention since the early 1960s ,asit isthei mportant crystal forfluorescent andsolid-statelasers . However ,it is hard to prepare large size sam-ples and dope high concentrationions in YAGcrystal .Conversely ,the fabrication of YAGtransparent ceram-ics is relatively…     

Characterization of Y_2O_2S∶Eu ~(3+), Mg~(2+), Ti~(4+) Long-Lasting Phosphor Synthesized by Flux Method

Long lastingphosphorescence(LLP)isaproper tyofphosphorswithlongdecaytime,rangingfroma fewminutestotensofhours[1].Inrecentyears,LLP materialshavebeenwidelyusedinmanyfieldssuch asroadsigns,emergencylighting,graphicarts,inte riordecoration,automobileinstrument,andoptical datastorage[2～4].Buttodate,theprogressonred phosphorescenceisveryslow.TheredLLPmaterialbasedonsulfide(CaS∶Eu3+)hasnearly3hafterglow.However,itisex tremelysensitivetomoistureandthuschemicallyun stable[5].CaTiO3∶Pr3+,BaT…     

Effect of microelements on microstructures and properties of Al-1. 2Mg-1. 3Si-0. 6Cu-0. 3Mn alloy

In order to save energy and protect environmentin automobile industry, one of the important methodsis to reduce the automotive weight[1 ～4]. Since the a-luminum alloys showsuch as high specific strength,good formability, good corrosion resistance, and re-cycling potential, they are said to be the ideal candi-date to replace heavier materials in the automotiveindustry[5 ～7].Recently, the heat -treatable 6000series aluminum alloys have been considered as theperfect light-weight material for au…     

Effect of Long-Term Intake of Y^3＋ in Drinking Water on Gene Expression in Brains of Rats

Rareearths(REs)includelanthanide,Sc,and Y.Withtheirwidespreadapplicationsinagriculture,industry,medicine,andstockbreeding,rareearth compoundsentertheecologicalenvironmentandhu manbodythroughfoodchains[1].Therefore,thelong termeffectsofREshavedrawntheattentionofmany researchers.Recentevidencesfrompublishedreports haveindicatedthattheneuraltoxicityofrareearthsis similartothatofAl3+[2],andthatrareearthsprobably impactthefunctionofbrain.Zhu[3],etal.foundthat rareearthshadacertaineffectontheinte…     

Thermochemical Study on Coordination Complex of Samarium with Salicylic Acid and 8-Hydroxyquinoline

It is knownthat rare earthions ,8-hydroxyquino-line and salicylic acid are antibacterial[1 ～5].Synthesisand characterization of the rare earth complexes withsalicylic acid were reported by Sun[6].Synthesis andcharacterization of the rare earth complexes …     

Effect of Fe2O3 Loading Amount on Catalytic Properties of Monolithic Fe2O3/Ce0.67Zr0.33O2 -Al2O3 Catalyst for Methane Combustion

Ce0.67Zr0.33O2-Al2O3 solid solution was prepared by the co-precipitation method. Fe2O3-based catalysts supported on the solid solution were obtained by the impregnation method. The article revealed that the optimal loading amount of Fe2O3 on Ce0.67Zr0.33 O2-Al2O3 in our experimental condition for catalytic combustion of methane was 8% （ mass fraction）. The prepared catalysts were characterized by BET, TPR, XRD analyses, and their catalytic activity was investigated after being calcined at 873 K and after being aged in water gas at 1273 K. When the loading amount of Fe203 was 8% （ mass fraction）, the catalyst held the highest activity, and the best temperature speciality and thermal stability. The complete-conversion temperature of methane for fresh and aged sample was 788 and 838 K, respectively. The range between the light-off temperature and the complete-conversion temperature was only 15 K. The characterization results of XRD indicated that Fe2O3 was well dispersed on the Ce0.67Zr0.33O2-Al2O3 matrix. The results of BET and TPR were in good harmony with the catalytic activity results.     

新型CeO2-Fe2O3联合催化剂用于催化CO还原NO

采用3种不同的方法合成新型的以Fe₂O₃颗粒为载体的Ce-Fe复合氧化物催化剂,探究不同制备方式的复合氧化物催化剂的催化CO还原NO性能,并通过X射线衍射(XRD)、拉曼光谱(Raman)、氢气-程序升温还原(H2-TPR)、X射线光电子能谱(XPS)表征来对催化剂进行探究。结果证明Ce-Fe复合氧化物具有较高的催化活性,硝酸水热法Ce-Fe复合氧化物在900℃时脱硝率可达到99%以上。XRD中显示硝酸水热样品中CeO₂峰向高角度偏移,并且晶格常数变小。Raman结果说明硝酸水热样品CeO₂的振动峰向左大幅度偏移,结合XRD说明硝酸水热法可以形成Ce-O-Fe固溶体。H2-TPR说明氧化还原性:硝酸水热法>硝酸浸渍法>普通浸渍法。XPS结果说明硝酸水热法形成的Ce-O-Fe固溶体可以促进Fe³⁺向Fe²⁺、晶格氧向吸附氧的转换,这体现出复合催化剂Ce、Fe之间的联合作用。在整个反应过程中Fe₂O₃作为载体可以提供大量晶格氧,Ce-O-Fe固溶体的存在决定了复合催化剂的高催化活性。     

Sol-gel processed Ce^3＋, Tb^3＋ codoped white emitting phosphors in Sr2Al2SiO7

Sr2Al2SiO7：Ce^3＋, Tb^3＋ white emitting phosphors were fabricated using the sol-gel method. X-Ray Powder Diffraction （XRD） analysis confirmed the formation of Sr2Al2SiO7：Ce^3＋, Tb^3＋. Scanning Electron Microscopy （SEM） observation indicated that the microstructure of the phosphor consisted of regular fine grains with an average size of about 0.5-1 μm. Luminescence properties were analyzed by measuring the photoluminescence spectra. The Ce^3＋, Tb^3＋-codoped Sr2Al2SiO7 phosphors showed four main emission peaks： one at 414 nm for Ce^3＋ and three at 482, 543, and 588 nm for Tb^3＋. The emission spectra of the samples with different doping concentrations showed that the Tb^3＋ emission was dominant because of the persistent energy transfer from Ce^3＋. The decay characteristic was better than that prepared by the solid-state process in the comparable condition. The codoped phosphor displayed long persistent white phosphorescence.     

Biochemical effects of gadolinium chloride in rats liver and kidney studied by ^1H NMR metabolomics

The biochemical effects of gadolinium chloride were studied using high-resolution IH nuclear magnetic resonance (NMR) spec-troscopy to investigate the biochemical composition of tissue (liver and kidney) aqueous extracts obtained from control and gadolinium chlo-ride (GdCl3) (10 and 50 mg/kg body weight, intraperitoneal injection, i.p.) treated rats. Tissue samples were collected at 48, 96 and 168 h p.d. after exposure to GdCl3, and extracted using methanol/chloroform solvent system. 1H NMR spectra of tissue extracts were analyzed by pat-tern recognition using principal components analysis. The liver damages caused by GdCl3 were characterized by increased succinate and de-creased glycogen level and elevated lactate, alanine and betaine concentration in liver. Furthermore, the increase of creatine and lactate, and decrease of glutamate, alanine, phosphocholine, glycophosphocholine (GPC), betaine, myo-inositoi and trimethylamine N-oxide (TMAO)levels in kidney illustrated kidney disturbance induced by GdCl3.     

Synthesis of neodymium modified CeO2-ZrO2-Al2O3 support materials and their application in Pd-only three-way catalysts

Ce-Zr-Al-Nd2O3 (CZAN) support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffraction (XRD), low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperature pro-grammed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The Pd-only three-way catalysts (Pd-TWC) supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd2O3 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox prop-erty. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified sam-ples possessed more Ce3+ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.     

Preparation of High-Surface Area Nano-CeO2 by Template-Assisted Precipitation Method

The high-surface area nano-CeO2 was prepared by Ce（NO3）3 by precipitation method, with surfactant cetyhrimethyl ammonium bromide （CTAB） as templating agent. The effects of the precipitating agents, reaction temperature, ageing time, and calcination temperature on the surface area, as well as the pore structure and the mean crystallite size of nano-CeO2 were studied. It was found that the reaction of Ce（NO3）3 with NaOH in the presence of CTAB at 90℃ for 12 h yieldsed a cerium oxide/surfaetant mixture, which after calcination at 400℃ resulted in high-surface area nano-CeO2. The mean crystallite size of CeO2 was approximately 6 nm, surface area was in excess of 200 m^2· g ^- 1, pore size was approximately 9 nm, and the pore distribution was concentrative. Moreover, the surface area can still reach 147 m^2·g^- 1 after calcination at 700 ℃, which showed the good thermal stability of the CeO2. The number of oxygen vacancies in the structure of CeO2 corresponded with the surface area of CeO2, and the high surface area was propitious to the formalion of oxygen vacancies.     

Synthesis kinetics and thermophysical properties of La_2（Zr_（0.7）Ce_（0.3））_2O_7 ceramic for thermal barrier coatings

La2(Zr0.7Ce0.3)2O7 (LZ7C3) ceramic was synthesized by solid state reaction with La2O3, ZrO2 and CeO2 as starting materials. The synthesis kinetics, phase structure, mass loss and microstructure were studied by thermo gravimetric-different thermal analyzer (TG-DTA), X-ray difference (XRD) and scanning electron microscopy (SEM). The thermal conductivity and thermal expansion coefficient were measured by laser-flash method and pushing-rod method, respectively. XRD results showed that LZ7C3 was a mixture of La2Zr2O7 (LZ, pyro- chlore) and La2Ce2O7 (LC, fluorite). The lowest synthesis temperature and time of LZ7C3 were 1400 oC and 5 h. There were no peaks of La2O3 when the powder granularity was about 0.82 μm in the synthesis process. The atom ratio La:Zr:Ce of prepared LZ7C3 powder was very close to 10:7:3 which was the theory value of LZ7C3. The thermal conductivity of LZ7C3 decreased gradually with the temperature increased up to 1200 oC, and was located within 0.79 to 1.02 W/(m·K), which was almost 50% lower than that of LZ, whereas its thermal expansion coefficient was larger and the value was 11.6×10-6 K-1.     

共沉淀法制备稀土石榴石Ln3Al5O12(Ln=Y, Ce, Yb)

以Y2O3、Yb2O3、Al(NO3)3.9H2O和Ce(NO3)3.6H2O为原料,NH4HCO3、NH3.H2O做复合沉淀剂,用共沉淀法制备纳米稀土石榴石Ln3Al5O12(LnAG,Ln=Y,Ce,Yb)粉体。用TG/DTA、XRD、SEM、TEM等手段对LnAG前驱体及煅烧后的粉体进行表征。结果表明,用上述方法在1 000℃煅烧3h可得到分散性好、形状规则且粒径为50nm左右的Y3Al5O12、Yb3Al5O12、Y2.9Ce0.1Al5O12石榴石粉体,但不能得到Ce3Al5O12石榴石,合成石榴石粉体的最佳煅烧温度为1 050℃以上。     

The effect of sample freezing on proton magic-angle spinning NMR spectra of biological tissue

Magic-angle spinning (MAS) has recently been shown to enhance spectral resolution in NMR examinations of intact biological tissue ex vivo. This work demonstrates that freezing certain tissue samples before examination by 1H MAS NMR can have a marked effect on their spectra. Spectra of rat kidney after freezing in liquid nitrogen, compared with spectra before freezing, showed a significant increase in signal intensities from alanine (>100%), glutamine (>40%), and glycine (>100%), and a decrease in signals assigned to lipids and other macromolecules. Some resonances--such as from leucine, valine, isoleucine, and aspartate--only became visible after freezing the tissue. These observations suggest that low temperature storage of tissue necropsies or biopsies might affect the results of a MAS NMR analysis, possibly resulting in the misinterpretation of metabolite changes to pathogen or disease effects.     

Photocatalytic activity of cerium-doped mesoporous TiO2 coated Fe3O4 magnetic composite under UV and visible light

A novel kind of magnetically separable photocatalyst of cerrium-doped mesoporous titanium dioxide coated magnetite (Ce/MTiO2/ Fe3O4) was prepared and its activities under UV and visible light were reported. The catalysts with Ce/MTiO2 shell and Fe3O4 core were pre-pared by coating photoactive Ce/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4, TBT) with pre-cursors of ammonium ceric nitrate and TBT in the presence of Fe3O4 particles. The MTiO2 shell was for photocatalysis, the Fe3O4 core was for separation by the magnetic field and the doped Ce was used to enhance the photocatalytic activity of MTiO2. The morphological, struc-tural and optical properties of the prepared samples were characterized by Brunauer-Emmett-Teller (BET) surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of cerrium-doped content on the photocatalytic activity was studied and the result revealed that 0.5 mol.% Ce/MTiO2/Fe3O4 exhibited highest photoactivity. The photocatalytic activities of obtained photocatalysts under UV and visible light were estimated by measuring the degradation rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxi-dation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Ce/MTiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by an external magnetic filed. So, the photocatalyst can be reused without any mass loss. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.