Lanthanum nitrate decomposition by both temperature programmed heating and citrate gel combustion

Thermal decomposition of lanthanum nitrate to lanthanum oxide was carried out by both temperature programmed heating (TPH) and citrate-gel combustion. The temperature programmed heating was carried out under flow of oxidizing (air), neutral (nitrogen) and reducing (25 vol.% hydrogen+argone mixture) gases, and the processes were controlled by simultaneous thermogravimetry and differential thermal analysis. It was shown that hydrogen atmosphere helps to reduce temperatures of all decomposition steps. The results of TPH were utilized to check the nature of residues in the products of lanthanum nitrate-to-oxide conversion performed via citrate-gel combustion technique.     

钯作基体改进剂FIA－HG－GFAAS法测定锗及其机理研究

采用钯，钯－镁作基体改进剂，ＦＩＡ－ＨＧ－ＧＦＡＡＳ法成功地测定了锗。灵敏度、精密度和分析速度都得到很大的提高。峰值吸收的特征质量８．０ｐｇ，检出限１０．９ｐｇ，相对标准偏差０．３４％，同时探讨了基体改进剂钯的稳定作用机理及锗在石墨管中的原子化机理。     

Independence of the brittle–ductile transition from the rubber particle size for impact‐modified poly(vinyl chloride)

A series of acrylic impact modifiers (AIMs) with different particle sizes ranging from 55.2 to 927.0 nm were synthesized by seeded emulsion polymerization, and the effect of the particle size on the brittle–ductile transition of impact‐modified poly(vinyl chloride) (PVC) was investigated. For each AIM, a series of PVC/AIM blends with compositions of 6, 8, 10, 12, and 15 phr AIM in 100 phr PVC were prepared, and the Izod impact strengths of these blends were tested at 23 °C. For AIMs with particle sizes of 55.2, 59.8, 125.2, 243.2, and 341.1 nm, the blends fractured in the brittle mode when the concentration of AIM was lower than 10 phr, whereas the blends showed ductile fracture when the AIM concentration reached 10 phr. It was concluded that the brittle–ductile transition of the PVC/AIM blends was independent of the particle size in the range of 55.2–341.1 nm. When the particle size was greater than 341.1 nm, however, the brittle–ductile transition shifted to a higher AIM concentration with an increase in the particle size. Furthermore, the critical interparticle distance was found not to be the criterion of the brittle–ductile transition for the PVC/AIM blends. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 696–702, 2006     

Synthesis and Structural Characterization of Adduct [La(NO_3)_3·4H_2O]·2(BQEB)

Differentkindsofopenchaincrownethershavebeensynthesizedasthemodelcompoundsofionophoresandtheirinteractionswithsodium,potassiumandrareearthionshavealsobeenstudiedl'z.PanshowedCe(III)yieldedalf1complexwithl,8-bis(8'-quinolyloxy)-3,6-dioxaandtheCe(IIl)ioncoordinatedbothtoetheroxygenandquinolinenitrogenatoms3.TUmInleridentifiedtwolanthanidenitratecomplexeshavingastoichiometryof3:2(3RE:2L)'.InordertostUdythefunctionsofbothquinolineandbenzenering,introducedintothepolyetherchain,a1inearpolyether…     

石墨炉原子吸收光谱法直接测定血样中硒

用石墨炉原子吸收光谱法，以硝酸铜和硝酸铵为基体改进剂，塞曼效应扣背景，采用标准加入法可直接测定血样中硒，回收率为95％～105％，相对标准偏差为5．8％，检出限为96pg，测定结果准确可靠。     

Trace elemental determination in alcohol automotive fuel by electrothermal atomic absorption spectrometry

Suitable analytical methodologies were developed allowing direct determination of As, Cu, Fe, Pb, Sb and Sn in alcohol fuel samples by electrothermal atomic absorption spectrometry. Different chemical modification approaches were tested and compared in terms of analytical performance and in practical terms. Experimental conditions were optimized allowing little sample dilution and use of calibration curves prepared with aqueous inorganic analyte standards. Methodologies were tested with analyte spiked alcohol samples. Good analyte recoveries from spiked alcohol samples, precision better than 10% and limits of detection in the sub μg l⁻¹ range were achieved.     

土壤微生物ATP、脱氢酶和尿素酶活性的ED50值评价外源镧的生物毒性

０IntroductionRareearthsarenowappliedwidelyinChina，whichcanimprovecropsyieldsandthetheirqualit－ies犤１犦．Thebeneficialeffectsmaybeduetothestimu－latoryeffectsoftheseelementsonthenutrientuptakebyplantsorontheincreasingofchlorophyllsynthesisintheplants犤２犦．Whilealotofresearcheshavebeendoneontheimprovednutritionofcropsafterapplica－tionofrareearths，muchlessattentionhasbeenpaidtothedeteriorationofsoilqualityduetotheapplicationofrareearthsforyears犤３犦．Scientistshavediscoveredthataccumula…     

分光光度法研究镧与间乙酰基偶氮氯膦(CPAmA)配合物的形成反应

本文用分光光度法研究了间乙酰基偶氮氯膦试剂在水溶液中的离解作用和质子化作用;镧与间乙酰基偶氮氯膦配合物的组成和β型配合物形成反应的条件和动力学特征,并测定了α型配合物的积累稳定常数     

Aromatization of methane over different Mo-supported catalysts in the absence of oxygen

Both acidity and structure of the support are important factors in converting methane to aromatics. Lower SiO₂/Al₂O₃ ratio seems to favor the aromatization of methane over the Mo/HZSM-5 catalyst. When Pt is added as a modifier the activity of Mo/HZSM-5 catalyst will decrease slightly, but coke formation will enhanced.