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Spectroscopic investigations of Gd_3Sc_2Ga_3O_(12) garnet doped with cr^(3+) and Nd^(3+) ions

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Journal of Rare Earths 2009年第4期27卷 560-563页

作者： K.Lemański P.J.Dereń A.Gagor W.Strek Institute of Low Temperatures and Structure Research Polish Academy of Sciences

Absorption, excitation and emission spectra as well as decay time measurements at 10, 77, and 300 K were perfumed for Gd3Sc2Ga3O12 garnet single-crystal doped with cr^3＋ and Nd^3＋ ions. Strong reabsorption of cr3＋ emission by Nd3＋ absorption lines was ob- served. The assignments of f-f and d-d transitions were proposed. The broad emission band of chromium ions is an indication that weak/intermediate crystal field strength is present at the cr3＋ site.

关键词： Gd3Sc2Ga3O12 crystal reabsorption cr Nd rare earths

Three-liquid-phase extraction and separation of V(V) and cr(VI) from acidic leach solutions of high-chromium vanadium–titanium magnetite

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Chinese Journal of Chemical Engineering 2018年第7期26卷 1451-1457页

作者： Pan Sun Kun Huang Xiaoqin Wang Na Sui Jieyuan Lin Wenjuan Cao Huizhou Liu CAS Key Laboratory of Green Process and Engineering Institute of Process Engineering Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

A new method by liquid–liquid–liquid three phase system, consisting of acidified primary amine N1923(abbreviated as A-N1923), poly(ethylene glycol)(PEG) and (NH_4)_2SO_4 aqueous solution, was suggested for the separation and simultaneous extraction of V(V) and cr(VI) from the acidic leach solutions of highchromium vanadium–titanium magnetite. Experimental results indicated that V(V) and cr(VI) could be selectively enriched into the A-N1923 organic top phase and PEG-rich middle phase, respectively, while Al(III)and other co-existing impurity ions, such as Si(IV), Fe(III), Ti(IV), Mg(II) and Ca(II) in acidic leach solutions,could be enriched in the(NH_4)_2SO_4 bottom aqueous phase. During the process for extraction and separation of V(V) and cr(VI), almost all of impurity ions could be removed. The separation factors between V(V) and cr(VI) could reach 630 and 908, respectively in the organic top phase and PEG middle phase, and yields of recovered V(V) and cr(VI) in the top phase and middle phase respectively were all above 90%.Various effects including aqueous p H, A-N1923 concentration, PEG added amount and(NH_4)_2SO_4 concentration on three-phase partitioning of V(V) and cr(VI) were discussed. It was found that the partition of cr(VI) into the PEG-rich middle phase was driven by hydrophobic interaction, while extraction of V(V) by A-N1923 resulted of anion exchange between NO_3^- and H_2V_(10)O_(28)^(-4). Stripping of V(V) and cr(VI) from the top organic phase and the middle PEG-rich phase were achieved by mixing respectively with NaNO_3 aqueous solutions and Na OH-((NH_4)_2SO_4 solutions. The present work highlights a new approach for the extraction and purification of V and cr from the complex multi-metal co-existing acidic leach solutions of high-chromium vanadium–titanium magnetite.

关键词：钒钛磁铁矿分离因素 cr 抽取沥滤高铬杂质离子 N1923

制革污泥堆场中含cr污泥胶体在不同pH和离子强度条件下稳定性及迁移行为研究

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环境科学学报 2023年第3期43卷 244-254页

作者：徐铁兵师碧玲吕媛康子沨阎秀兰商建英杨潇河北省环境科学研究院石家庄050037 中国科学院地理科学与资源研究所地表格局与模拟重点实验室北京100101 中国科学院大学中丹学院北京100049 中国农业大学土地科学与技术学院北京100193 河北师范大学地理科学学院石家庄050000

制革污泥中含有大量的重金属cr,毒性大,易迁移,会威胁人类健康.本研究以某停用制革污泥露天堆场作为研究对象,在揭示制革污泥污染特征的基础上,提取污泥中的胶体颗粒,研究不同pH、离子强度下含cr污泥胶体稳定性及迁移情况.结果表明,堆... 详细信息

制革污泥中含有大量的重金属cr,毒性大,易迁移,会威胁人类健康.本研究以某停用制革污泥露天堆场作为研究对象,在揭示制革污泥污染特征的基础上,提取污泥中的胶体颗粒,研究不同pH、离子强度下含cr污泥胶体稳定性及迁移情况.结果表明,堆场污泥中cr含量为5170~25000 mg·kg^(-1),cr赋存形态以铁锰氧化物结合态为主,总cr含量表深层污泥之间无明显分异.表层污泥pH=4.35,处于有氧环境,好氧菌与嗜酸菌为优势菌群;深层污泥pH=7.30,处于无氧环境,厌氧菌为优势菌群.深层污泥中含有大量含cr污泥胶体(含cr量为7.851 mg·g^(-1)),在中性和碱性条件下较为稳定,迁移性强;在酸性条件下快速聚沉,迁移性弱.离子强度越高,污泥胶体越容易聚沉、移动性显著降低,且Ca^(2+)比Na^(+)更容易引起污泥胶体的聚沉和弱移动性,因此,向污泥胶体中引入Ca^(2+)可作为降低cr迁移风险的有效途径.本研究成果可为全面认识同类型制革污泥堆场的污染风险评估和修复方案设计提供重要的理论支撑.

关键词： cr 环境条件污泥胶体稳定性迁移行为

Shape Memory Effect of As-aged Fe-14Mn-5Si-8cr-4Ni-0.2C Alloy

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Journal of Materials Science & Technology 2000年第4期16卷 424-426页

作者： Yuhua WEN, Ning LI and Mingjing TU (Department of Materials Shaping and Controlling Engineering, Sichuan University, Chengdu 610065, China) Department of Materials Shaping and Controlling Engineering Sichuan University Chengdu 610065 China

The effects of aging temperature on shape memory effect, mechanical properties and microstruc-ture of Fe-14Mn-5Si-8cr-4Ni-0.2C shape memory alloy have been studied. The results showed that the second phase particles rich in chromium, manganese and silicon precipitate during aging, and thereby increase the hardness and strength of the alloy. The shape recovery ratio can be remarkably improved by aging and a maximum value can be obtained at 1223 K, which is 68% higher than that of the specimen in solid solution state. When the aging temperature is below 1223 K, the amount of second phase particles increases as the aging temperature increases. The size of austenite grain increases with increasing aging temperature. When the temperature is over 1223 K, the second phase particles can not precipitate. The lack of second phase particles and the increase of grain size make the hardness and shape recovery ratio drastically decrease, when the temperature is over 1223 K.

关键词： Mn Shape Memory Effect of As-aged Fe-14Mn-5Si-8cr-4Ni-0.2C Alloy As Fe cr Ni Si

Behavior of Zr-Rich Phase in a Cast NiAl-33.5cr-0.5Zr Alloy during Heat Treatment

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Journal of Materials Science & Technology 2001年第6期17卷 629-632页

作者： Hui LI, sJianting GUQ, Wanhui LAI and Shuhe WANG Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China [Manuscript received July 7, 2000, in revised form October 11, 2000] Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

There are many Zr particles in as-cast NiAl-33.5cr-0.5Zr (at. pct) alloy, which usually exist at the edge of eutectic of β-NiAl and α-cr. After air and furnace cooling solution treatments, for 14000C, 2 h and 1450℃, 1 h, pure Zr phase remains in the furnace cooling (F.C.) state alloys and Ni2AlZr phase forms in the air cooling (AC.) state alloys. During solution treatment at 14500C, bulk and "fish bone"shape Zr-rich phases form respectively in F.C. and AC. state alloys. A ’river’?shape Ni2AlZr phase forms after 14500C for lh F.C. and 8500C for 12 h, F.C.. The alloy has less pure Zr and Ni2AlZr phase after 14000C with both air and furnace cooling followed by 8500C and 9500C for 12 h, F.C. aging treatments, respectively. Additionally, there is a ternary eutectic of NiAIZr and a phase enriched Zr and cr forms at the edge of the eutectic of β-NiAl and α-cr in the alloy treated at 14000C, 2 h, F.C. and 9500C, 12 h, F.C.

关键词： NiAl Zr Behavior of Zr-Rich Phase in a Cast NiAl-33.5cr-0.5Zr Alloy during Heat Treatment cr Cast

寡氧单胞菌、水稻秸秆和蚯蚓协同修复cr(Ⅵ)污染土壤

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农业环境科学学报 2023年第11期42卷 2440-2452页

作者：沈松蓉陈云康茜琳向媛羚耿育红张伟韩颖西南科技大学生命科学与工程学院四川绵阳621010 西南科技大学分析测试中心四川绵阳621010

为探究水稻秸秆和蚯蚓联合抗cr细菌对cr污染土壤的修复效果和机制,本研究通过室内模拟试验探讨细菌(寡氧单胞菌,Stenotrophomonas sp.,F)、水稻秸秆(S)、细菌+水稻秸秆(SF)、水稻秸秆+蚯蚓(赤子爱胜蚓,Eisenia foetida,SE)和细菌+水稻秸... 详细信息

为探究水稻秸秆和蚯蚓联合抗cr细菌对cr污染土壤的修复效果和机制,本研究通过室内模拟试验探讨细菌(寡氧单胞菌,Stenotrophomonas sp.,F)、水稻秸秆(S)、细菌+水稻秸秆(SF)、水稻秸秆+蚯蚓(赤子爱胜蚓,Eisenia foetida,SE)和细菌+水稻秸秆+蚯蚓(SFE)对50、300 mg·kg^(-1) cr(Ⅵ)污染土壤的修复效果,生物有效态cr的变化及总cr和cr(Ⅵ)在各粒径团聚体中的分布。结果表明:在试验早、中、后期各处理的总cr和cr(Ⅵ)去除率逐渐增加,在50、300 mg·kg^(-1) cr(Ⅵ)暴露后期SFE处理的总cr和cr(Ⅵ)去除率最高,其总cr去除率分别为35.68%、35.29%,cr(Ⅵ)去除率分别为99.28%、75.33%。SFE处理显著降低了土壤氧化还原电位,增加了土壤p H和有机质含量,并促进了微团聚体凝聚胶结为大团聚体。在0、50、300 mg·kg^(-1) cr(Ⅵ)暴露下SE处理大团聚体的占比最高,与CK相比分别增加了14.57、9.51、9.85个百分点,与SFE相比分别增加了3.73、4.09、3.28个百分点。各处理对cr化学形态的影响为SFE>SF>SE>S>F,在整个试验过程中除F处理外,其余处理中各化学形态的占比都随试验时间的延长而稳定变化。与CK相比,在50、300 mg·kg^(-1) cr(Ⅵ)暴露后期SFE处理中可交换态的占比分别降低了35.55、21.02个百分点,残渣态的占比分别增加了22.45、12.51个百分点。总cr主要分布在大团聚体中,cr(Ⅵ)主要分布在微团聚体中,所有处理各粒径团聚体中的总cr和cr(Ⅵ)含量都随试验时间的延长而降低,SFE处理显著降低了大团聚体中总cr和微团聚体中cr(Ⅵ)的含量。研究表明,在50、300 mg·kg^(-1) cr(Ⅵ)暴露下水稻秸秆、蚯蚓和寡氧单胞菌协同处理显著增加了土壤总cr和cr(Ⅵ)的去除率,降低了生物有效态cr的占比并改善了cr在团聚体中的分布。

关键词： cr 寡氧单胞菌水稻秸秆蚯蚓土壤团聚体

Factors Affecting Transformation Temperatures in Fe-Mn-Si-cr-Ni Shape Memory Alloy

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Journal of Materials Science & Technology 2000年第5期16卷 537-539页

作者： Yuhua WEN+, ding LI and Mingjing TU (Department of Materials Shaping and Controlling Engineering, Sichuan University, Chengdu 610065, China) Department of Materials Shaping and Controlling Engineering Sichuan University Chengdu 610065 China

The effects of prestrain and annealing temperature on phase transformation temperatures in Fel4Mn5Si8cr4Ni shape memory alloy have been studied. The results showed that when the annealing temperature was 673 K, both the At and the Ms temperatures increased appreciably as the prestrain increased, the As temperature increased slightly with increasing prestrain; the resistivity difference at 303 K between the heating and cooling curve also increased with increasing prestrain, which agreed with the recovery strain. The shape memory effect in Fe-Mn-Si-cr-Ni shape memory alloy is caused by the stress-induced γ→ε martensite transformation and its reverse transformation. When the prestrain was 10%, the Ms temperature decreased remarkably as the annealing temperature increased.

关键词： Factors Affecting Transformation Temperatures in Fe-Mn-Si-cr-Ni Shape Memory Alloy Fe Mn cr Ni Si

Forming Mechanism of Gaseous Defect in Ti-48Al-2cr-2Nb Exhaust Valves Formed with Permanent Mold Centrifugal Casting Method

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Journal of Materials Science & Technology 2001年第5期17卷 569-571页

作者： Research Notes Wenbin SHENG, Jingjie GUO, Yanqing SU, Hongsheng DING and Jun JIA School of Materials Science and Engineering, Harbin Institute of Technology. Harbin 150001, China Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

A method combining theoretical analysis with experiment is adopted and the flowing process of Ti-48A1-2cr-2Nb alloy melt poured in a permanent mould during the centrifugal casting process has been analyzed. A mathematical model of the filling process is established and the forming mechanism of internal gaseous defect is summarized. The results of calculation show that the melt fills the mould with varying cross-section area and inclined angle. The filling speed of the cross-section is a function of filling time. The cross-section area is directly proportional to the filling speed and the inclined angle is inversely proportional to the filling speed at a given rotating speed of the platform. Both of them changes more obvious near the mould entrance. The gaseous defect can be formed in several ways and the centrifugal field has an important influence on the formation of the defect. In addition, the filling process in centrifugal field has been verified by wax experiments and the theoretical analysis are consistent with experimental results.

关键词： Forming Mechanism of Gaseous Defect in Ti-48Al-2cr-2Nb Exhaust Valves Formed with Permanent Mold Centrifugal Casting Method Mold Ti Al cr

Monitoring the Heavy Element of cr in Agricultural Soils Using a Mobile Laser-Induced Breakdown Spectroscopy System with Support Vector Machine

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Chinese Physics Letters 2016年第8期33卷 64-68页

作者：谷艳红赵南京马明俊孟德硕余洋贾尧方丽刘建国刘文清 Key Laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsChinese Academy of Sciences University of Science and Technology of China

Due to its complicated matrix effects, rapid quantitative analysis of chromium in agricultural soils is difficult without the concentration gradient samples by laser-induced breakdown spectroscopy. To improve the analysis speed and accuracy, two calibration models are built with the support vector machine method： one considering the whole spectra and the other based on the segmental spectra input. Considering the results of the multiple linear regression analysis, three segmental spectra are chosen as the input variables of the support vector regression （SVR） model. Compared with the results of the SVR model with the whole spectra input, the relative standard error of prediction is reduced from 3.18% to 2.61% and the running time is saved due to the decrease in the number of input variables, showing the robustness in rapid soil analysis without the concentration gradient samples.

关键词： of is on LIBS in Monitoring the Heavy Element of cr in Agricultural Soils Using a Mobile Laser-Induced Breakdown Spectroscopy System with Support Vector Machine SVR cr with