20#管线钢在役焊接HAZ的组织与性能研究

在役焊接过程中，管内流动介质的快速冷却，易使接头出现氢致裂纹。对20^#管线钢在不同冷却条件和不同焊接线能量下的HAZ的组织性能进行了模拟研究。结果表明，在流动水冷却下，HAZ出现较多的贝氏体、马氏体和MA组元等不平衡组织，使得HAZ的硬度高达330HvN5，性能最差。采用大的线能量焊接，形成较多的上贝氏体和粒状贝氏体组织，对改善接头性能有利。因此，在避免烧穿的前提下增大焊接线能量或减小管内介质的冷却能力，减少高硬度不平衡相的形成，可以降低HAZ氢致开裂敏感性。     

Separation of Monovinyl and Divinyl Protochlorophyllides Using C30 Reverse Phase High Performance Liquid Chromatography Column: Analytical and Preparative Applications

A new, high performance liquid chromatography method has been developed for the separation of monovinyl- and divinyl-protochlorophyllides, using commercially available, C₃₀ reverse phase column and isocratic elution. This method can be used both for analytical applications and preparative scale purification of monovinyl- and divinyl-protochlorophyllides using the same column where submilimolar concentrations of the crude protochlorophyllide extract can be separated in one run. The purity of the obtained protochlorophyllides was demonstrated by spectroscopic methods, as well by the formation of aggregates in toluene.     

Thermal transformations of selected transition metals oxyhydroxides

We investigated the features of the glass transition relaxation of two room temperature ionic liquids using DSC. An important observation was that the heat capacity jump, that is the signature of the glass transition relaxation, shows a particularly strong value in this type of new and promising materials, candidates for a range of applications. This suggests a high degree of molecular mobility in the supercooled liquid state. The study of the influence of the heating rate on the temperature location of the glass transition signal, allowed the determination of the activation energy at the glass transition temperature, and the calculation of the fragility index of these two ionic glass-formers. It was concluded that this kind of materials belong to the class of relatively strong glass-forming systems. This revised version was published online in July 2006 with corrections to the Cover Date.     

A novel greener glycosidation using an acid-ionic liquid containing a protic acid

The glycosidations of glucopyranosyl diethyl phosphite and alcohols using an ionic liquid, 1-n-hexyl-3-methylimidazolium trifluoromethanesulfonimidide (C₆mim[NTf₂]) containing a protic acid, trifluoromethanesulfonimide (HNTf₂), as a novel solvent-catalyst system, effectively proceeded under mild conditions to give the corresponding glycosides in good to high yields. Furthermore, this acid-ionic liquid combination could be reused many times for the glycosidations without any loss in efficiency.     

30MnNbXt钢组合匹配接头性能的研究

本文为新钢种30MnNbXt设计了一种独特的组合匹配接头,研究了底层奥氏体焊条的合金系统及填充层结构钢焊条的强度对抗裂性的影响,探讨了底层高组配、填充层低组配的组合匹配焊缝特征区的组织特点及接头的力学性能。在西德WS1.7—2.0/3.5型综采支架立柱中应用表明,组合匹配接头可使30MnNbXt钢在室温下焊接时不产生裂纹;接头在焊后状态的使用性能完全符合产品技术条件要求。     

硼铁矿高炉冶炼过程中铀的物化行为

硼铁矿中含有微量铀，采用液态核乳胶照相，铀的价态分析，Ｘ射线衍射分析，电子探针等手段，测定了矿石中的铀以晶质铀矿物形成存在。矿石经高炉冶炼大部分ＵＯ３被还原成ＵＯ２在渣中富集，渣中的铀仍以晶质铀矿物形式存在。铀与其它矿物镶嵌关系及颗粒度大小均发生了变化。     

Experimental Observables on Nuclear Liquid Gas Phase Transition

Progress on nuclear liquid gas phase transition （LGPT） or critical behavior has been simply reviewed and some signals of LGPT in heavy ion collisions, especially in NIMROD data, are focused. These signals include the power-law charge distribution, the largest fluctuation of the fragment observables, the nuclear Zipf law, caloric curve and critical exponent analysis etc.     

Synthesis and characterization of liquid crystalline side‐chain block copolymers containing luminescent 4,4′‐bis(biphenyl)fluorene pendants

A series of new liquid crystalline homopolymers, copolymers, and block copolymers were polymerized from styrene‐macroinitiator ( SMi ) and methacrylates with pendent 4,4′‐bis(biphenyl)fluorene ( M1 ) and biphenyl‐4‐ylfluorene ( M2 ) groups through atom transfer radical polymerization (ATRP). The number‐average molecular weights (Mn) of polymers P1 ‐ P4 were 10,007, 14,852, 6,275, and 10,463 g mol^?1 with polydispersity indices values of 1.21, 1.15, 1.31, and 1.22, respectively. All polymers exhibit the nematic phase. The thermal, mesogenic, and photoluminescent properties of all polymers were investigated. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4564–4572, 2007     

Liquid Chromatography-Mass Spectrometry Determination of Six 5-Nitroimidazoles in Animal Feedstuff

A liquid chromatography-mass spectrometry method for the determination of the coccidiostats metronidazole, ronidazole, dimetridazole, secnidazole, tinidazole and ipronidazole in feedstuff was developed. The 5-nitroimidazoles were extracted from animal feed with a pH 2 phosphate buffer solution followed by a solid phase extraction procedure based on HLB cartridges. The liquid chromatographic separation of the extracts was performed on a C₁₈ bonded silica column applying a gradient of elution with pH 4.3 ammonium acetate buffer solution and acetonitrile. Quantification for each 5-nitroimidazole was carried out monitoring its molecular ion [M + H]⁺ obtained by positive electrospray ionisation mode. A pool of feedstuffs was used to optimise and validate the method. Linearity, quantification limit, intra-day and inter-day reproducibility and accuracy were estimated using this pool of feedstuffs spiked with the drugs. For the confirmatory assay, several fragment ions from each 5-nitroimidazole were obtained and monitored. The method was applied successfully to determine 5-nitroimidazoles in feedstuff at level of 0.05 mg kg⁻¹.     

中碳钙硫易切削钢夹杂物形态控制

在实验室进行了1 kg坩埚实验,研究了中碳高硫结构钢钙处理前后夹杂物的形态、尺寸及组?结果表明:钢钙处理后获得了可以改善钢切削性的纺锤形夹杂物,夹杂物的平均纺锤形率为68.11%,并且随钢中[Ca]/[S]增加夹杂物纺锤形化趋势增加;钙处理后小于2.5 μm的夹杂物占夹杂物总量的76.05%,夹杂物细小、弥散分布于钢基体中;夹杂物类型以钙铝酸盐芯硫化物外壳的复合夹杂物、(Mn,Ca)S形式的硫化物为主,有少量的铝酸钙与CaS的复合夹杂物;含钙硫的45钢铸态钢锭比普通45钢铸态钢锭切削性能有所改善.