利用富铈混合稀土改善工业纯铝中富铁相形貌的研究

利用金相分析方法研究了富Ce混合稀土变质对含不同Fe量的工业纯铝的组织和其中富铁相形貌的影响。试验结果表明,随着Fe含量的增加,富铁相由弥散细小的颗粒状向短棒状、长针状转变;富Ce混合稀土变质使铝中的富铁相由长针状变为弥散细小的颗粒状。随着稀土含量的增加,-αAl晶粒逐渐细化,富铁相尺寸及数量逐渐减小。添加0.5%稀土时,-αAl晶粒细化效果最佳,而且富铁相呈细小颗粒状均匀分布在-αAl基体的晶界处。本文还对稀土改善富铁相的机制进行了分析。     

混合稀土对共晶Al-2％Fe合金组织形态的影响

研究了富La混合稀土对共晶Al-2％Fe合金组织形态的影响。当混合稀土加入量较少时，合金中的α—Al相为明显的胞状枝晶；随着混合稀土加入量的增加，α-Al枝晶优先形核生长得到抑制，共晶Al3Fe相得到细化；当稀土加入量增至0．6％(质量分数)共晶Al3Fe相尺寸逐渐增大。并对混合稀土对共晶Al-2％Fe合金组织形态的影响机制进行了探讨。     

富铈混合稀土对AZ81合金组织与性能的影响

研究了富铈混合稀土对挤压铸造AZ81合金的显微组织和力学性能的影响。结果表明:加入不同含量富铈混合稀土的合金中都出现了一种新相Al11(Ce,La)3相,Al11(Ce,La)3相数量增多而Mg17Al12相则减少,能细化合金的组织晶粒,其细化作用在添加了1.5%富铈混合稀土的镁合金中尤为明显,但是当富铈混合稀土加入量大于2.0%时,合金中Al11(Ce,La)3相开始长大以粗大长杆状存在;在富铈混合稀土含量为1.5%时,AZ81合金的室温和150℃的综合力学性能达到最佳效果,超过2.0%时合金的室温和150℃综合力学性能开始下降;合金试样的拉伸断口带有局部韧窝的解理断裂和韧性断裂的混合特征。     

用改进回归正交试验法从混合稀土-偶氮胂Ⅲ-EDTA显色体系中测定四种单一稀土的研究

本文应用回归正交试验法,在混合稀土-偶氮胂Ⅲ-EDTA显色体系中,对La,Ce,Pr,Nd四种稀土进行四因子一次回归正交实验。在650nm处得到吸收峰高与稀土浓度间的回归方程。再用标准系列加入法得到各稀土浓度对吸收峰高的变化率(偏偏微)。由回归方程求得偏徽方程组,求解该方程组可得四种单一稀土的含量。这种新方法由于应用正交优化原理,故比其他单一稀土测定方法具有明显的优点:不必分离即可同时测定单一稀土。对包头和龙南混合稀土的测定结果表明,该法可靠,误差≤2％。     

混合稀土和镧施加后苗期玉米体内稀土元素分布的剂量／效应关系研究

以潮土和玉米分别为供试土壤和作物进行盆栽实验.当混合稀土或La与土壤混合后,苗期玉米根系和地上部分中稀土元素含量存在明显的剂量-效应关系.施加混合稀土时,玉米根系和地上部分中轻稀土和Gd含量分别在10和50mg@kg-1风干土时出现显著性聚集效应;在La施用量为5和10mg@kg-1风干土时,玉米根系和地上部分中La含量分别出现显著性聚集效应.施加较大剂量混合稀土或La时,玉米根系和地上部分中Gd含量均出现显著性正异常;当混合稀土施用量为50mg@kg-1时,玉米根系和地上部分中均出现显著性Ce负异常现象;苗期玉米地上部分和根系LaCe和LaSm比值均随混合稀土或La施用量增大而呈增加趋势;在高剂量稀土(＞50mg@kg-1),尤其在La作用时,玉米根系吸收的La向地上部分运移明显受到抑制.     

不同季节叶面喷施镧、铈对油菜产量及品质的影响

以油菜为试材,采用田间小区试验方法,研究了单一稀土La,Ce叶面喷施对同一土壤条件下、不同季节(春季和秋季)油菜产量和营养品质的影响,以期为单一轻稀土农用提供理论依据。结果表明:不同季节种植油菜其营养品质存在明显差异,秋季油菜可溶性糖和维生素C含量较高,可滴定酸和硝酸盐含量较低,糖酸比较高,而春季则相反;La,Ce处理促进春秋两季油菜茎叶干、鲜物重增加,增加干鲜比,增幅大小为Ce处理>La处理;La,Ce处理增加油菜茎叶中可溶性糖含量,降低可滴定酸含量,增加糖酸比,其中春秋两季分别以Ce和La处理作用明显;同时降低油菜茎叶中的维生素C和硝酸盐的含量,其中春秋两季分别以La和Ce处理作用明显;La,Ce处理降低油菜茎叶中的重金属Cu,Zn,Cd,Pb,Ni等元素的含量,降幅大小为Ce处理>La处理。     

铈及混合稀土对Fe-36Ni低膨胀合金凝固组织的影响

研究了Ce及混合稀土对Fe-36Ni低膨胀合金凝固组织的影响,结果表明:加Ce或者混合稀土处理后,合金中分别形成了大量高熔点的Ce2O3颗粒和(Ce,La)2O2S复合第二相颗粒,错配度理论计算表明,Ce2O3,Ce2O2S和La2O2S的(0001)面与Fe-36Ni的(100)面分别具有6.21%,5.77%和5.42%的较低错配度,因此Ce2O3和(Ce,La)2O2S可以作为有效的非均质形核核心,使凝固组织的等轴晶比例增加,等轴晶尺寸减小,合金凝固组织得到显著细化。     

钇和铈对AM50镁合金显微组织和力学性能的影响

为了开发低成本、高强度和耐高温的新型镁合金，研究了微量Y，Ce复合对AM50镁合金显微组织和力学性能的影响。结果表明：Y和Ce复合加入AM50镁合金，能明显细化晶粒，由于显微组织的改善，合金的室温和高温力学性能得到明显提高，当稀土加入量为0．6％Ce-0．3％Y（质量分数）时，合金晶粒细化效果较好，其室温和高温（150℃）力学性能比较理想。     

三异丙氧基混合稀土掺杂改性聚苯乙烯的研究

用廉价的三异丙氧基混合稀土杂改性聚苯乙烯，利用红外光谱，紫外与可见光吸收光谱，荧光光谱，X射线光电子能谱，扫描电镜等手段对其表下，并测定其冲击强度。证明了改性聚苯乙烯中存在着稀土金属离子与苯环的配位作用；改性聚苯乙烯的荧光强度比纯聚苯乙烯的高，其中以稀土含量为1．0％时其荧光强度最高，同时改性后聚苯乙烯抗冲性能显著提高，表明三异丙氧基混合稀土对聚苯乙烯有较好的增韧作用。     

稀土对LC4超硬铝组织性能的影响

系统地研究了La、Ce、Nd、Y和混合稀土对LC4超硬铝组织性能和时效行为的影响。结果表明,五种稀土均能不同程度地改善铸锭组织、提高再结晶温度和抗蚀性,其中只有镧能明显提高时效硬化效应并稍微提高强度,铈的作用恰好相反,其它稀土的作用不明显。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.