2A12铝合金粉末与TC4钛合金热等静压粉-固扩散连接北大核心

利用热等静压(Hot Isostatic Pressing,HIP)工艺实现2A12铝合金粉末和Ti-6Al-4V钛合金的HIP粉-固扩散连接,对比研究了Cu作为中间层材料对扩散连接性能的影响。结果表明:对于2A12铝合金粉末和Ti-6Al-4V钛合金直接HIP扩散连接其连接接头处生成了3种不同的金属间化合物,这些化合物的存在对扩散连接接头的连接质量有有害的影响;当以Cu作为中间层时,扩散主要发生在Cu/Al一侧,Cu/Al共晶反应生成的液相渗透到铝合金粉末颗粒之间。当以Cu作为中间层时,扩散连接区域的硬度下降,剪切强度增加,和直接扩散连接相比,剪切强度增加了64%,达到23 MPa。     

加热温度对镍中间层热轧钛钢复合板微观组织及力学性能的影响

以Ni为中间层制备钛/钢轧制复合板,借助扫描电镜、能谱仪、X射线衍射仪和Instron万能拉伸试验机等分析手段,研究了850～950℃加热温度对钛钢复合板力学性能和显微组织的影响。结果表明:当加热温度在850～900℃时,剪切强度随温度升高而升高;加热温度为900～950℃时,剪切强度随温度升高而降低,最高剪切强度都在900℃时获得。以Ni为中间层有效阻止了Fe和C等元素扩散到Ti侧形成金属间化合物,界面化合物种类不随温度变化,但化合物量随温度升高而增加。轧制温度为850℃时,界面上金属间化合物非常少,对应的剪切强度最低;轧制温度为900℃时,复合板界面剪切强度最优,与之相对应的界面结构是较为充分的元素扩散以及少量的金属间化合物;轧制温度为950℃时,金属间化合物层急剧变厚,TiNi_3和孔洞急剧增多,因而严重削弱了界面的剪切强度。     

锻造变形对扩散连接TC4钛合金的影响

本文开展了TC4钛合金棒材扩散连接及锻造工艺实验,研究了锻造变形量对扩散连接界面显微组织和力学性能的影响规律。结果表明,采用950℃、140 MPa、4 h的扩散连接工艺,TC4钛合金连接界面实现了冶金结合,合金强度达到母材强度的95%以上,延伸率为7%,合金在扩散区发生脆性断裂。扩散连接的TC4钛合金经过高温锻造后,扩散连接界面完全消失,显微组织由等轴α相、次生α相与少量的β相组成;随着锻造变形量的增加,等轴α相的尺寸逐渐降低、次生α相体积分数增大,合金强度呈现升高趋势;当变形量为40%时,等轴α相和次生α相含量达到较优匹配度,抗拉强度达到950 MPa,延伸率达到17.5%,锻造后合金的断裂方式转变为韧性断裂。     

Ti6Al4V和Al2A12的扩散连接界面组织及力学性能

采用热等静压(HIP)工艺连接Al12A12和Ti6Al4V两种不同的航空航天用材料.利用扫描电镜、能谱仪和X射线衍射仪观察连接过渡区的微观组织和组成的演化,并测试其主要的力学性能.结果表明:采用热等静压制备这两种材料的界面连接好;Ti/Al反应层界面处形成了不同的金属间化合物,例如,Al₃ Ti、TiAl₂和TiAl;连接接头处硬度为163 HV,界面连接处剪切强度达到了23 MPa,比只添加镀层而无中间层的连接强度提高了约17.9%,但低于带有中间层的连接强度.由于过烧和孔隙的形成使得断裂方式是脆性断裂.由此可知,在热等静压成形过程中异种材料的元素发生了相互扩散,在扩散连接处形成了不同的金属间化合物,这些金属间化合物影响连接处的力学性能.      

Ti6Al4V和Al2A12的扩散连接界面组织及力学性能

采用热等静压(HIP)工艺连接Al2A12和Ti6Al4V两种不同的航空航天用材料.利用扫描电镜、能谱仪和X射线衍射仪观察连接过渡区的微观组织和组成的演化,并测试其主要的力学性能.结果表明:采用热等静压制备这两种材料的界面连接好;Ti/Al反应层界面处形成了不同的金属间化合物,例如,Al_3Ti、TiAl_2和TiAl;连接接头处硬度为163 HV,界面连接处剪切强度达到了23 MPa,比只添加镀层而无中间层的连接强度提高了约17.9%,但低于带有中间层的连接强度.由于过烧和孔隙的形成使得断裂方式是脆性断裂.由此可知,在热等静压成形过程中异种材料的元素发生了相互扩散,在扩散连接处形成了不同的金属间化合物,这些金属间化合物影响连接处的力学性能.     

退火温度对TC4ELI钛合金大规格环材组织和力学性能的影响

采用光学显微镜、万能材料试验机和金属摆锤式冲击试验机研究了退火温度对TC4ELI钛合金大规格环材(Φ3384 mm/Φ3300 mm×1950 mm)的显微组织和力学性能的影响.显微组织分析结果表明:退火温度在850℃以下时,TC4ELI钛合金大规格环材退火后的显微组织与热加工态的显微组织基本相同;900℃退火后,TC...     

17-4PH不锈钢和钛固态扩散连接的组织结构和性能

本文以钛和17-4沉淀硬化不锈钢为对象进行了固态扩散连接试验,试验条件为真空、单向压力3.5MPa,800~1050℃(50℃步幅)保温30min以及950℃保温30~180min(30min步幅)。采用光学显微镜,场发射扫描电子显微镜和X射线衍射技术对连接试样进行检测。直到850℃保温30min时,扩散界面上才形成Fe Ti相;然而,在保温30min时高于850℃以及950℃的任意保温时间内,会形成a-Fe+X、x、Fe2Ti和Fe Ti相及混合相。在950℃保温30min和以30?180min步幅的试验中,试样在1000℃时获得扩散连接最高的抗拉强度~326MPa,最高的剪切强度~254MPa及最高的冲击初性~24J。保温120min时获得的最高抗拉强度为?323MPa,最高剪切强度?243MPa及最高冲击韧性~221。连接件的残余应力随连接温度的升高及时间的延长而增大。     

热等静压温度对V-4Cr-4Ti/HR2钢连接界面及性能的影响

以AuNi合金作为过渡层材料,采用热等静压(HIP)方法进行V-4Cr-4Ti/HR2钢(SS)扩散连接.利用扫描电镜(SEM)、能谱仪(EDS)及剪切试验分析了接头的扩散层显微组织、微区成分和力学性能.研究表明:采用AuNi过渡层材料,能够实现V-4Cr-4Ti/HR2的扩散连接;HIP温度为850℃时,接头质量良好,其剪切强度为39MPa;V、Fe、Ni等主要元素的平均扩散深度为20μm左右;在SS侧,扩散层较为均匀,在V-4Cr-4Ti侧,形成了Au的富集层和NixVy的富集层,两层呈相互交替的层状分布.     

2A12铝合金粉末与TC4钛合金热等静压粉-固扩散连接

利用热等静压(Hot Isostatic Pressing,HIP)工艺实现2A12铝合金粉末和Ti-6A1-4V钛合金的HIP粉-固扩散连接,对比研究了Cu作为中间层材料对扩散连接性能的影响.结果表明:对于2A12铝合金粉末和Ti-6A1-4V钛合金直接HIP扩散连接其连接接头处生成了3种不同的金属间化合物,这些化合...     

钛合金超塑成形/扩散连接的数值模拟及工艺研究

利用有限元软件Marc对钛合金TC4板的超塑成形/扩散连接(SPF/DB)进行数值模拟.通过模拟获得优化的压力-时间(p-t)曲线,为后续的超塑成形/扩散连接试验提供参考基础.经过试验得到钛合金TC4板超塑成形/扩散连接的最佳工艺参数为:超塑成形,θ=900 ℃、p=2.5 MPa、t=790 s;扩散连接,θ=900 ℃、p=3.0 MPa、t=80 min. 钛合金TC4;超塑成形/扩散连接(SPF/DB);数值模拟;工艺研究     

Simultaneous determination of polyamines, N-acetylated polyamines and the polyamine analogues BE-3-3-3 and BE-4-4-4-4 by capillary gas chromatography with nitrogen-phosphorus detection

IgM paraproteins from patients with CANOMAD (chronic ataxic neuropathy, ophthalmoplegia, M-protein, agglutination, anti-disialosyl antibodies) react with NeuAc(alpha 2-8)NeuAc epitopes on a wide range of gangliosides including GQ1b, GT1a, GD1b and GD3. The tissue distribution of reactive antigens in human peripheral nerve has not been addressed in detail. In addition, the origin of these antibodies is unknown. Here we report that purified anti-disialosyl paraproteins from two affected patients bind a wide array of human peripheral nerve structures including dorsal root ganglia, dorsal and ventral root axons, femoral and oculomotor nerves. We also show that these paraproteins bind lipopolysaccharides of Campylobacter jejuni isolates from 3/3 cases of Miller Fisher syndrome, and to a less frequent extent, from cases of Guillain-Barré syndrome and enteritis controls. In conjunction with our previous studies, these data provide a possible causal link between the origin and pathogenic effects of anti-disialosyl antibodies in human paraproteinaemic neuropathy.     

汽车青铜QSn4—42．5板材的试制

本文依据国内某用户的要求，对QSn4-4-2.5板材生产锭坯的熔铸工艺和加工工艺进行探索，并论述了该合金板材生产的工艺制度对期产品的性能的影响。     

(3R,4S)-3-[4-(4-fluorophenyl)-4-hydroxypiperidin-1-yl]chroman-4,7-diol: a conformationally restricted analogue of the NR2B subtype-selective NMDA antagonist (1S,2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)- 1-propanol

(1S,2S)-1-(4-Hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol (CP-101,606, 1) is a recently described antagonist of N-methyl-D-aspartate (NMDA) receptors containing the NR2B subunit. In the present study, the optimal orientation of compounds of this structural type for their receptor was explored. Tethering of the pendent methyl group of 1 to the phenolic aromatic ring via an oxygen atom prevents rotation about the central portion of the molecule. Several of the new chromanol compounds have high affinity for the racemic [3H]CP-101,606 binding site on the NMDA receptor and protect against glutamate toxicity in cultured hippocampal neurons. The new ring caused a change in the stereochemical preference of the receptor-cis (erythro) compounds had better affinity for the receptor than the trans isomers. Computational studies suggest that steric interactions between the pendent methyl group and the phenol ring in the acyclic series determine which structures can best fit the receptor. The chromanol analogue, (3R,4S)-3-[4-(4-fluorophenyl)-4-hydroxypiperidin-1- yl]chroman-4,7-diol (12a, CP-283,097), was found to possess potency and selectivity comparable to CP-101,606. Thus 12a is a new tool to explore the function of the NR2B-containing NMDA receptors.     

HV—4B分析仪的应用

本文介绍ＨＶ－４Ｂ型微机碳硫分析仪与ＨＢ－２Ｂ型高引燃炉配套使用,在分析测定钢铁中的碳、硫元素时取代传统的非水－碘量滴定法,针对传统的化学分析法存在的问题,进行分析,改造,引进了高速仪器分析法,并取得了较好的效果。     

Dual inhibition of human type 4 phosphodiesterase isostates by (R, R)-(+/-)-methyl 3-acetyl-4-[3-(cyclopentyloxy)-4-methoxyphenyl]-3- methyl-1-pyrrolidinecarboxylate

Purified recombinant human type 4 phosphodiesterase B2B (HSPDE4B2B) exists in both a low- and a high-affinity state that bind (R)-rolipram with Kd's of ca. 500 and 1 nM, respectively [Rocque, W. J., Tian, G., Wiseman, J. S., Holmes, W. D., Thompson, I. Z., Willard, D. H., Patel, I. R., Wisely, G. B., Clay, W. C., Kadwell, S. H., Hoffman, C. R., and Luther, M. A. (1997) Biochemistry 36, 14250-14261]. Since the tissue distribution of the two isostates may be significantly different, development of inhibitors that effectively inhibit both forms may be advantageous pharmacologically. In this study, enzyme inhibition and binding of HSPDE4B2B by (R, R)-(+/-)-methyl 3-acetyl-4-[3-(cyclopentyloxy)-4-methoxyphenyl]-3-methyl-1-pyrrolidin ecarboxylate (1), a novel inhibitor of phosphodiesterase 4 (PDE 4), were investigated. Binding experiments demonstrated high-affinity binding of 1 to HSPDE4B2B with a stoichiometry of 1:1. Inhibition of PDE activity showed only a single transition with an observed Ki similar to the apparent Kd determined by the binding experiments. Deletional mutants of HSPDE4B2B, which have been shown to bind (R)-rolipram with low affinity, were shown to interact with 1 with high affinity, indistinguishable from the results obtained with the full-length enzyme. Bound 1 was completely displaced by (R)-rolipram, and the displacement showed a biphasic transition that resembles the biphasic inhibition of HSPDE4B2B by (R)-rolipram. Theoretical analysis of the two transitions exemplified in the interaction of (R)-rolipram with HSPDE4B2B indicated that the two isostates were nonexchangeable. Phosphorylation at serines 487 and 489 on HSPDE4B2B had no effect on the stoichiometry of binding, the affinity for binding, or the inhibition of the enzyme by 1. These data further illustrate the presence of two isostates in PDE 4 as shown previously for (R)-rolipram binding and inhibition. In contrast to (R)-rolipram, where only one of the two isostates of PDE 4 binds with high affinity, 1 is a potent, dual inhibitor of both of the isostates of PDE 4. Kinetic and thermodynamic models describing the interactions between the nonexchangeable isostates of PDE 4 and its ligands are discussed.     

N-[4-(1,1''-biphenyl)methyl]-4-(4-thiomorpholinylmethyl) benzenamines as non-oxazolidinone analogues of antimycobacterial U-100480

Twenty-three patients underwent conventional arteriography and 3D contrast enhanced magnetic resonance angiography explorations. The study was limited to the iliofemoral arteries (13 segments for each patient). Each segment was classified as having 0-49%, 50-99% or 100% stenosis. Overall results were excellent with K = 0.822, sensitivity 92% and specificity 93%. Segment by segment analysis corroborated the overall results except for the internal iliac arteries and the deep femoral arteries, demonstrating the limitations of this technique in this series.     

特种铸造方式下QAl10-4-4铝青铜组织演变规律

采用OM、XRD、EDS及宏观硬度测试等手段研究了真空吸铸和离心铸造方式下QAl10-4-4铝青铜的组织演变规律。结果表明,两种铸造方式下组织中相的种类、析出顺序及初始析出温度有较大的不同。真空吸铸条件下,接近铸态的组织由α相、β’相、KⅡ和KⅢ相构成,其相的析出顺序为KⅡ→α→KⅢ;离心铸造条件下,接近铸态的组织中还含有KⅠ和KⅣ相,其相的析出顺序为α+KⅠ→KⅡ→KⅣ→KⅢ,对应的相初始析出温度整体高于真空吸铸,且α相的初始析出温度远高于真空吸铸。KⅠ相的析出与合金中Fe的含量及Fe/Ni值有关,两者越高,越容易析出KⅠ相。两种铸造方式下,随着淬火温度的降低,合金的硬度在整体上均呈现先快速降低后趋于稳定的趋势。但是,真空吸铸样品在淬火温度大于900℃时出现脆化。β→α+KⅢ共析分解对合金的硬度无明显影响。     

4-(对-甲氧基苯氨基重氮基)-4'-硝基偶氮苯的合成及其与汞(Ⅱ)的显色反应

合成了新显色剂4-(对甲氧基苯氨基重氮基)-4'-硝基偶氮苯(PMADNA),并研究了该试剂在Triton X-100存在下与汞的显色反应。结果表明,在pH 10.5的Na2B4O7-NaOH缓冲介质中,Hg(Ⅱ)与试剂形成稳定的1∶2红色络合物,最大吸收波长位于576 nm,表观摩尔吸光系数为1.25×105L.mol-1.cm-1,汞的质量浓度在0~0.8μg/mL范围内服从比尔定律,用酒石酸钠-焦磷酸钠-氟化钠作混合掩蔽剂,可以提高Fe3+,Ni2+,Cu2+,Cd2+的允许量。方法用于废水中微量汞     

1-(2,6-二氯-4-硝基苯)-3-(4-硝基苯)-三氮烯分光光度法测定钴

研究了新试剂1-(2,6-二氯-4-硝基苯)-3-(-4-硝基苯)-三氮烯(DCNPNPT)与钴(Ⅱ)显色反应的适宜条件.在表面活性剂Triton X-100存在下,Na2B4O7-NaOH缓冲液(pH.9.3)介质中,钴(Ⅱ)与DCNPNPT形成黄色络合物(12),其最大吸收波长为545nm,用双峰双波长法测定络合物的表观摩尔吸光系数ε=1.08×105,钴在0～240μg/L范围内符合比尔定律.此法已用于VB12针剂和矿样中微量钴(Ⅱ)的测定,结果满意.     

4-(trans-4-Methylcyclohexyl)-4-oxobutyric acid (JTT-608). A new class of antidiabetic agent

During an investigation of drugs for improving the beta-cell response to glucose, we found that 4-cyclohexyl-4-oxobutyric acid selectively improved glucose-stimulated insulin release and glucose tolerance in both normal and diabetic rats. A series of 4-cycloalkyl-4-oxobutyric acids and related compounds were synthesized and evaluated for their effects on the glucose tolerance test and fasting euglycemia. This study elucidated the structural requirements for drug activity and determined that the optimum compound was 4-(trans-4-methylcyclohexyl)-4-oxobutyric acid 7 (JTT-608). This compound improved glucose tolerance from an oral dose of 3 mg/kg and did not change fasting euglycemia even at an oral dose of 30 mg/kg. Selective improvement of glucose-induced insulin secretion was observed in studies using neonatal streptozotocin rats (nSTZ rats) and perfused pancreases isolated from nSTZ rats.