酶澄清绿茶饮料研究

研究了不同种类酶对绿茶茶汤抗沉淀效果,并采用HPLC分析了经单宁酶处理后茶汤中酯型儿茶素的变化。结果表明,单宁酶、果胶酶、木瓜蛋白酶对绿茶茶汤抗沉淀影响达极显著水平。多酚类和咖啡碱都有不同程度地减少,但没有达到显著水平。经木瓜蛋白酶处理的茶汤蛋白质含量减少,氨基酸含量同其他处理样相比有一定的增加。结合方差分析和感官审评结果表明,单宁酶对绿茶茶汤抗沉淀效果最好,单宁酶最佳作用时间为2h。在一定范围内,随着单宁酶作用时间的延长,茶汤中酯型儿茶素的总量在不断减少,茶汤的透光率随着酯型儿茶素的减少在不断增大。     

Strengthening contribution of precipitates and anisotropy of yield strength in Al-Li alloys 2090 and 2090 Ce

1　ＩＮＴＲＯＤＵＣＴＩＯＮＭｏｓｔｉｎｖｅｓｔｉｇａｔｅｓｈａｖｅｄｅｍｏｎｓｔｒａｔｅｄｔｈａｔＡｌ Ｌｉａｌｌｏｙｓｗｉｔｈｔｅｘｔｕｒｅｓｈｏｗｏｐｔｉｍｉｚｅｄｓｔｒｅｎｇｔｈ ｔｏｕｇｈ ｎｅｓｓｃｏｍｂｉｎａｔｉｏｎｓ[1～ 3].Ｔｈｅｒｅｆｏｒｅ,ｔｈｅｒｍｏｍｅｃｈａｎｉ ｃａｌｔｒｅａｔｍｅｎｔｓｓｕｃｈａｓｒｏｌｌｉｎｇａｎｄｓｔｒｅｔｃｈｉｎｇａｒｅｃｏｍ ｍｏｎｌｙｅｍｐｌｏｙｅｄｔｏｉｍｐｒｏｖｅｔｈｅｏｖｅｒａｌｌｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓｏｆＡｌ Ｌｉａｌｌｏｙ…     

埋弧药芯焊丝Nb、V合金元素含量对堆焊熔敷金属耐腐蚀性能的影响

1Cr13马氏体不锈钢常用于制造冶金轧辊、汽轮机叶片、泵轴等零件,这些零件因腐蚀产生的表面微缺陷常导致零件断裂失效,向堆焊熔敷金属中过渡适量特定合金元素,可有效改善其耐腐蚀性能。文中在1Cr13药芯焊丝配方的基础上,通过添加不同含量的铌铁和钒铁(3.2 wt.%、6 wt.%、10 wt.%)制备了三种埋弧药芯焊丝进行堆焊试验,分析堆焊熔敷金属的显微组织,并研究Nb、V含量对堆焊熔敷金属耐腐蚀性能的影响。结果表明,随着药芯焊丝中铌铁和钒铁含量的增加,堆焊熔敷金属中析出相的数量逐渐增多,这些析出相为含Nb、V的碳氮化物,能有效抑制富Cr析出相的形成,提高基体中的有效Cr含量;大量均匀分布的析出相有利于腐蚀从多位置发生,促进了堆焊熔敷金属的均匀腐蚀,改善了堆焊熔敷金属的耐腐蚀性能。但含Nb和V的析出相过度析出会使基体中大量C、N原子脱溶,导致堆焊熔敷金属硬度下降。     

Influence of Electric Field on Mechanical Properties of Al-Li Alloy Containing Cerium and Electronic Mechanism

Ｒｅｃｅｎｔｌｙ ,ｍａｎｙｍａｔｅｒｉａｌｒｅｓｅａｒｃｈｅｒｓｈａｖｅｃｏｍｅｔｏｒｅａｌｉｚｅｔｈａｔｔｈｅｅｌｅｃｔｒｏｎｉｃｃｈａｒａｃｔｅｒｈａｓａｄｅｃｉｓｉｏｎａｌｒｏｌｅｏｎｍａｔｅｒｉａｌｐｒｏｐｅｒｔｉｅｓａｎｄｍｉｃｒｏｓｔｒｕｃｔｕｒｅ[1～ 3] .Ｔｈｅｓｅｗｏｒｋｓｒｅｖｅａｌａｎｅｗｍｅｃｈａｎｉｓｍｔｏｍａｔｅｒｉａｌｂｅｈａｖｉｏｒａｎｄａｎｅｗｕｎ ｄｅｒｓｔａｎｄｉｎｇｅｌｅｃｔｒｏｎｔｈｅｏｒｙｏｆａｌｌｏｙ .Ａｄｄｉｔｉｏｎ ａｌｙ,ｔｈｅｅｆｆｅｃｔｏｆａｎｅ…     

Pore Structure Evolution of Lanthana–Alumina Systems Prepared through Coprecipitation

Pure Al₂O₃ and different compositions of La₂O₃–Al₂O₃ samples have been prepared through coprecipitation. Even after heating at 1300°C, the compositions La₂O₃·11Al₂O₃ and La₂O₃·13Al₂O₃ had higher surface area compared to the pure Al₂O₃ and the La₂O₃·Al₂O₃ composition. Ethanol washing is an effective way for improving the textural stability of pure Al₂O₃ and La₂O₃–Al₂O₃ samples. The effect of steam on the thermal stability of La₂O₃·11Al₂O₃ has also been studied. La₂O₃·11Al₂O₃ sample is found to be stable in steam.     

高性能铜合金QBD-6

采用电磁搅拌水平连铸,破碎铸造组织并通过高温退火细化铸造组织中的析出物"Ni-P"化合物,经过20辊轧机的成品轧制,生产的QBD-6高性能铜合金板带材具有高强度、高弹性、高导电和高光洁度等特性,可替代进口合金,如:MF202、CAC5以及部分低强度的C7025。成功应用于引线框架材料、连接器、端子以及电动工具中的电机电刷部件。     

Zr—4合金中第二相的研究

应用透射电子显微镜研究了Zr-4合金经各种热处理后的微观结构,确定了第二相的晶体结构。经β相固溶处理后,板条α-Zr晶界上析出的第二相为C_(15)型Zr(Fe、Cr)_2Laves相,重新在α相区不同温度加热后存在C_(15)型私C_(14)型两种结构的Zr(Fe、Cr)_2Laves相。此外,本文对Zr-4合金中第二相的种类进行了讨论。     

Infrared transmission spectra of Cd<Subscript>1−x</Subscript>Zn<Subscript>x</Subscript>Te (x = 0.04) crystals

Three indicators (T₁₀₀₀, T₅₀₀₀, and T₁₀₀₀/T₅₀₀₀) are used to appraise the infrared (IR) transmission spectra for Cd_1−xZn_xTe (CZT) slices. By comparing the values of these three indicators, four typical types of IR spectra are characterized for CZT crystals. The CZT crystals possessing the four types of IR spectra are different in microstructures, especially the densities and sizes of Te precipitates, the free carrier concentrations, and the resistivities. Mechanisms for the elimination of tiny and dense Te precipitates are given by analyzing the variation of the IR transmittance in the range of 500–5000 cm⁻¹ during the annealing process.     

Ferrihydrite in water wells and bacterial enrichment cultures

The chemical and mineralogical composition of Fe(III)-precipitates formed in water wells and laboratory cultures was examined. Ferrihydrite, a poorly ordered Fe(III)-oxide of bulk formula 5Fe₂O₃ · 9H₂O, was detected by X-ray diffraction analysis in all samples. The crystallinity varied from one sample to another. Fe was the only major element detected by energy-dispersive X-ray spectrometry; several other elements were present at minor levels reflecting the chemical composition of the medium. The results suggest that the biologically-catalyzed iron encrustation of water wells begins with the initial formation of ferrihydrite.     

低碳钢中纳米尺度沉淀相的透射电子显微术研究

本文用电子显微镜技术对CSP工艺生产的普通低碳钢进行了研究，实验结果表明在试样中形成了大量细小的弥散沉淀粒子，电子衍射与XEDS分析证实这些沉淀是具有尖晶石结构的氧化铁以及硫化物，氧化物尺寸在20nm以下，大量分布在晶界和位错上。晶界上还有尺寸在100－400nm左右的硫化物粒子。这些沉淀使低碳钢的强度提高近一倍，同时塑性也大幅增高。