共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
Phase relations were determined in the systems of Li-(Mg,Zn,Ni) vanadates in the temperature range between 500° and 800°C. Each of the ternary systems Li2 O-(Mg, Zn, or Ni)O-V2 O5 is characterized by an orthovanadate: olivine-type LiMgVO4 , phenakite-type LiZnVO4 , and spinel-type LiNiVO4 . Mutual solid solutions form between them. Two solid solutions, a large region of the NiV2 O6 type and a complete series between MgV2 O6 and ZnV2 O6 , exist in the system (Mg,Zn,Ni)V2 O6 . The system (Mg,Zn,Ni)2 V2 O7 has an extensive solid-solution region based on Ni2 V2 O7 , whereas the system (Mg,Zn,Ni)3 V2 O8 is characterized by a complete series. 相似文献
3.
《Inorganic chemistry communications》2007,10(8):906-909
Vanadium complexes are extensively used in the chemical industry as oxidation catalysts. During the course of our investigations into vanadium oxidation catalysis, the rich reactivity of a vanadium(III) scorpionate analogue complex, (CpPOEtCo)VCl2(DMF) (1), was investigated. The octahedrally coordinated 1 was prepared by mixing vanadium(III) chloride with Na(CpPOEtCo) in DMF. The crystal structure of 1 has been determined through X-ray diffraction. Complex 1, C20H42Cl2CoNO10P3V, crystallizes in the monoclinic space group P21/c with a = 38.566(9) Å, b = 9.499(2) Å, c = 18.149(4) Å, and β = 100.485(4)° with Z = 8. Complex 1 was found to be an effective pre-catalyst for the oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone. The reactivity studies, oxidative catalytic ability, as well as X-ray structural characterization of (CpPOEtCo)VCl2(DMF) will be discussed. ((CpPOEtCo) = [η5-cyclopentadienyltris(diethylphosphito-κ1P) cobaltate(III)−; DMF = N,N-dimethylformamide). 相似文献
4.
5.
N,O,O′─三(对甲苯磺酰基)双(2─羟乙基)胺的合成 总被引:1,自引:0,他引:1
二乙醇胺和对甲苯磺酰氯在三乙胺存在下,反应生成N,0,O′-三(对甲苯磺酰基)双(2-羟乙基)胺,产率93%。从反应混合物中分离得副产物N,O-二(对甲苯磺酰基)双(2-羟乙基)胺。 相似文献
6.
7.
8.
9.
Tetsuya Asuke Robert West 《Journal of Inorganic and Organometallic Polymers and Materials》1995,5(1):31-42
Three polysilane polymers, (n-PrSiMe) n , (i-PrSiMe) n , and (sec-BuSiMe) n , were synthesized and characterized by DSC. UV spectroscopy, wide-angle X-ray diffraction, and optical microscopy, all at variable temperatures. The known thermochromic transition of (n-PrSiMe) n at ~48 C is associated with a change from an orthorhombic to an isotropic phase. (i-PrSiMe) n was examned as an insoluble and soluble (lowM w) fraction, both existing mainly in an orthohombic lattice at room temperature. (sec-BuSiMe) n has a mesophase structure at 25 C, undergoes a weak endothermic transition to a second (nematic) mesophase near 65 C, and becomes isotropic at ~160 C. 相似文献
10.
Ta/Sb掺杂的K0.5Na0.5Nb0.7TaxSb0.3-xO3(KNNSTx,x=0.06,0.09,0.12,0.15,0.18,0.21, 0.24)粉体经水热合成,Ta、Sb对粉体物相、微观结构的影响被系统研究,烧结后陶瓷的微观结构、介电性能表明:陶瓷物相均具有纯钙钛矿结构;随着Ta含量的增加陶瓷晶粒尺寸逐渐增大,x=0.09、0.12时较小粒径颗粒均匀分布在大颗粒的空隙之间,陶瓷密度增加;样品的介电常数随着Ta含量的增加x=0.06~0.12逐渐降低,x=0.15~0.24逐渐增加,居里温度均在350 ℃左右,且x=0.09、0.12时陶瓷介电损耗较小. 相似文献
11.
12.
N,N,N-三甲基-2,3-二(硬脂酰氧基)丙基氯化铵(CDESA)的生物降解性 总被引:1,自引:0,他引:1
采用活性环氧中间体失水甘油基三甲基氯化铵合成了一种阳离子双酯表面活性剂——N,N,N-三甲基-2,3-二(硬脂酰氧基)丙基氯化铵(CDESA),来代替传统的难降解的表面活性剂型柔软剂,如目前国内仍在大量使用的双十八烷基二甲基氯化铵(D1821)。对CDESA的好氧降解性能进行了研究:以天然环境中的生活沉降污泥作为微生物源,用河水稀释,经培养、驯化后用于测试降解时间和半衰期,并与D1821的好氧降解性能作了对比。结果表明,CDESA的半衰期为3 d,容易降解,而D1821半衰期为7 d,较难降解,CDESA生物降解性能优于D1821。 相似文献
13.
P. Ionita C. Ghica M. T. Caproiu G. Ionita 《Journal of Inorganic and Organometallic Polymers and Materials》2008,18(3):414-419
Water-soluble gold nanoparticles, capped with captopril, have been synthesized and characterized. Their average size is 2.3 nm,
with a spherical shape. These gold nanoparticles can be easily labeled with stable free radicals (4-amino-tempo) by a coupling
reaction performed in the presence of 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ). Both synthesized and spin-labeled
gold nanoparticles can be incorporated into much bigger (100 nm) silica nanoparticles using the Stober method, thus forming
hybrid metal (gold)-inorganic (silica) nanoparticles. These hybrid silica nanoparticles (containing or not spin-labeled gold
nanoparticles) can be easily spin-labeled with another stable free radical (4-isocyanato-tempo), leading to the formation
of a double spin-labeled material. In this way, some stable free radicals are attached on the gold surface while others are
attached on the silica surface. Three types of EPR spectra were recorded and discussed for the hybrid gold-silica nanoparticles:
(1) where the spin labels are attached to the embedded gold nanoparticles, (2) where the spin labels are attached to the silica
nanoparticles, and (3) in the case of the double spin labeled material where both gold and silica nanoparticles are spin-labeled.
Influence of different solvents on the EPR spectra is also discussed. 相似文献
14.
By introducing manganese to (Mg,Zn,Ni) divanadates, a series of thortveitite-type phases, Mn(Mg x Zn y Ni z )V2 O7 with x + y + z = 1, has been synthesized. The limits of x , y , and z can be represented by four phases: Mn(Mg0.2 Zn0.8 )V2 O7 , Mn(Mg0.5 Zn0.5 )V2 O7 , Mn(Mg0.1 Zn0.8 Ni0.1 )V2 O7 , and Mn(Mg0.4 Zn0.5 Ni0.1 )V2 O7 . Their cell dimensions are, respectively, a = 0.6734, 0.6737, 0.6749, and 0.6749 nm, b = 0.8806, 0.8819, 0.8816, and 0.8787 nm, c = 0.4748, 0.4750, 0.4752, and 0.4753 nm, and β= 102.16°, 102.15°, 102.23°, and 102.41°. 相似文献
15.
Up-conversion (Gd,Yb,Tb)PO(4) materials and their potential for bimodal imaging have received little attention in the literature. Herein, we report the first study on the up-conversion emission of (Gd,Yb,Tb)PO(4) nanocrystals synthesized via a hydrothermal method at 150 °C. These materials exhibit ultraviolet, blue and green up-conversion emissions upon excitation with a 980 nm continuous wave laser diode. The intensity of the blue-emission band at 479 nm, ascribed to the cooperative up-conversion emission of a pair of excited Yb(3+) ions, depends on the Yb(3+)/Tb(3+) concentration ratio, calcination temperature and particle size. Strong green up-conversion emission of Tb(3+) is observed at 543 nm for the (5)D(4)→(7)F(5) transition. Relaxometry measurements reveal that the nanocrystals are efficient T(2)-weighted (negative) contrast agents which, combined with visible-light emission generated by infrared excitation, affords them considerable potential for being used in bimodal, photoluminescence-magnetic resonance, imaging. 相似文献
16.
(S,S)-2,12-, (S,S)-2,13-, and (S,S)-2,14-diacetoxyheptadecanes: sex pheromone components of red cedar cone midge, Mayetiola thujae 总被引:1,自引:0,他引:1
Gries R Khaskin G Bennett RG Miroshnychenko A Burden K Gries G 《Journal of chemical ecology》2005,31(12):2933-2946
We identified, synthesized, and field-tested the sex pheromone of female red cedar cone midge Mayetiola thujae (Hedlin) (Diptera: Cecidomyiidae), a pest insect in red cedar Thuja plicata seed orchards. Coupled gas chromatographic (GC)-electroantennographic detection analyses of pheromone extract revealed three components (A, B, C) that elicited responses from antennae of males, all of which occurred below the detection threshold of the mass spectrometer and thus had to be identified without spectroscopic data. Taking into account (1) their retention indices (RI) on three GC columns (DB-5, DB-23, and DB-210), (2) intercolumn RI differentials, and (3) the molecular structures of known cecidomyiid pheromones, we synthesized seven candidate pheromone components: 2,10-, 2,11-, 2,12-, 2,13-, 2,14-, 2,15- and 2,16-diacetoxyheptadecanes. Of these, 2,12-, 2,13-, and 2,14-diacetoxyheptadecane had RIs on all columns consistent with those of A, B, and C and elicited strong antennal responses when tested at picogram levels. In field experiments with the twelve stereoselectively synthesized stereoisomers, only the SS-stereoisomers of 2,12-, 2,13-, and 2,14-diacetoxyheptadecane attracted male M. thujae. The three-component SS-stereoisomer blend was more attractive than the 12-component blend of all stereoisomers, suggesting that one or several nonnatural stereoisomers are inhibitory. One-, two-, and three-component lures of the SS-stereoisomers were equally effective in attracting male M. thujae, indicating redundancy in the pheromone. Identification of the M. thujae sex pheromone will allow development of pheromone-based monitoring, and possibly control, of M. thujae populations in T. plicata seed orchards. 相似文献
17.
《Journal of the European Ceramic Society》2006,26(9):1605-1610
Fifteen kinds of sodium rare earth silicate glasses and ceramics with (Na2O)35.7(RE2O3)7.2(SiO2)57.1 (RE = Y, Sm, Gd, Dy, Ho, Er and Yb) composition were synthesized from a mixture of Na2CO3, RE2O3 and SiO2. The densities of the glasses were in fairly good agreement with the theoretical densities and were 0.2–0.41 g cm−3 larger than those of the polycrystalline ceramics. The conductivities of the glasses are 1–2 orders lower than those of the ceramics and the highest electrical conductivity was achieved for the Yb ceramic sample with the smallest ion radius of RE3+. The electromotive force, EMF, of the potentiometric CO2 gas sensors using (Na2O)35.7(Y2O3)7.2(SiO2)57.1 glass and ceramic increased linearly with an increase in the logarithm of CO2 partial pressure, in accordance with Nernst's law. It was suggested from the slope of Nernst's equation that the two electron-transfer reaction associated with the carbon dioxide molecule takes place at the detection electrode above 450 °C. 相似文献
18.
分析了影响在桥梁上应用先进复合材料经济效益的因素,继之以考察正用于设计和建造先进复合材料结构物(包括桥梁)的设计方法和规范。介绍了不同的桥梁形式证明可采用先进复合材料(有时连同其它材料),并列举了对委托方和桥梁使用者的实惠。 相似文献
19.
Dielectric properties of (Sr1 - xPbx)TiO3-SPT (x = 0.05, 0.10 and 0.15) and phase transitions of SPT (x = 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) ceramic samples are investigated. At 10 kHz relative permittivity of SPT(x = 0.05) has one maximum, SPT(x = 0.10) and SPT(x = 0.15) show the main relative permittivity peaks and the secondary peaks at lower temperatures. The primary dielectric constant peaks could be due to the phase transitions from the paraelectric to ferroelectric phases on cooling and the source of the secondary peaks is not clear. Lattice parameter vs. composition, x shows a linear relation and phase transition has also a linear relation to the composition. 相似文献