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贻贝粉酶解液提取复合氨基酸 总被引：1，自引：1，他引：1
报道了以脱脂后的贻贝粉为原料，采用酶解法从其酶解液中分离提取复合氨基酸的工艺。其收率为２０％，纯度约为９０％。其中必需氨基酸（不计色氨酸）约占复合氨基酸总量的５５％，其氨基酸模式与ＦＡＯ／ＷＨＯ组织确定的模式及人乳模式进行了对照，通过适量添加个别氨基酸可使其配比接近人乳模式。 相似文献
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Summary The newly developed light sectioning method has been used to investigate some of the causes and costs of overbreak and underbreak. Investigations at the Aquamilpa Hydroelectric Project in Mexico have shown decreased overbreak and increased underbreak as a result of increased rock quality and decreased explosive energy. A new measure of explosive energy, the perimeter powder factor (PPF), has been defined and shown to be useful in the context of tunnel-wall rock damage. Tentative results indicate that explosive energy (PPF) may be a more important factor in producing underbreak, whereas rock quality may be a greater factor in producing overbreak. A site-specific equation is given for predicting overbreak or underbreak as a function of rock quality and explosive energy, with an evaluation of the cost of underbreak and overbreak. 相似文献
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Structural changes during dehydration and subsequent decomposition in thaumasite Ca3Si(SO4)(CO3)(OH)6·12 H2O were studied by in situ synchrotron powder diffraction between 303 and 1,098 K. Evolution of the crystal structure was observed through 28 structure refinements, by full profile Rietveld analysis performed in the P63 space group, between 300 and 417 K, whereupon the thaumasite structure was observed to breakdown. Within this temperature range, the cell parameters of thaumasite increased as a function of temperature in a nearly linear fashion up to about 393 K, at which temperature, a slight slope change was observed. Above 400 K, the thermogravimetric analysis revealed that the dehydration process proceeded very rapidly while the refined occupancy of water molecules dropped below a critical level, leading to instability in the thaumasite structure. At a same time, a remarkable change in the unit cell parameters occurring at about 417 K indicated that the crystal structure of thaumasite collapsed on losing the crystallization water and it turned amorphous. This result indicated that the dehydration/decomposition of thaumasite was induced by the departure of the crystallization water. At about 950 K, anhydrite and cristobalite crystallized from the thaumasite glass. 相似文献
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为探讨高原牌70kN和进口120，210kN瓷绝缘子的成分和结构性能，中采用原子吸收光谱（AAS）和X射线衍射（XRD）方法，对三类产品进行了检测。结果表明，有效成分除K2O外，70kN和210kN的SiO2,Al2O3,Fe2O3含量接近，主晶相基本相同，有刚玉，莫来石、石英和长石等；结晶相总量：70kN35%，120kN40%,210kN48%，这表明机械强度愈大，结晶相含量愈高，只需调整70kN原样的部分成分，粒度和工艺，即生产出高等级（如210kN)瓷绝缘子。 相似文献
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Kinetic study of the dehydroxylation of chrysotile asbestos with temperature by in situ XRPD 总被引：6，自引：0，他引：6
The kinetics of the dehydroxylation of chrysotile was followed in situ at high temperature using real-time conventional and
synchrotron powder diffraction (XRPD). This is the first time kinetics parameters have been calculated for the dehydroxylation
of chrysotile. The value of the order of the reaction mechanism calculated using the Avrami model indicates that the rate-limiting
step of the reaction is a one-dimensional diffusion with an instantaneous nucleation or a deceleratory rate of nucleation
of the reaction product. Hence, the rate-limiting step is the one-dimensional diffusion of the water molecules formed in the
interlayer region by direct condensation of two hydrogen atoms and an oxygen atom. The calculated apparent activation energy
of the reaction in the temperature range 620–750 °C is 184 kJ mol−1. The diffusion path is along the axis of the fibrils forming the fibers. The amorphous or short-range ordered dehydroxylate
of chrysotile is extremely unstable because forsterite readily nucleates in the Mg-rich regions. Moreover, it is less stable
than the dehydroxylate of kaolinite, the so-called metakaolinite, which forms mullite at about 950 °C. This difference is
interpreted in terms of the different nature of the two ions Mg2+ and Al3+ and their function as glass modifier and glass-forming ion, respectively.
Received: 10 April 2002 / Accepted: 7 January 2003
Acknowledgements This work is part of a COFIN project (04 Scienze della Terra, NR 17, 2000) supported by MURST. Dr Dapiaggi is kindly acknowledged
for help during the data collection at the Dipartimento di Scienze della Terra, University of Milan. 相似文献
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锇粉中杂质元素分析方法研究 总被引：2，自引：0，他引：2
利用ＩＣＰ＿ＭＳ技术建立了锇粉中痕量杂质元素的分析方法。在浓ＨＮＯ３介质中，锇以ＯｓＯ４形式挥发除去，分离锇基体后，可直接测定的痕量元素达５０余种。取样量０．１ｇ，测定限为０．２～２４６ｎｇ／ｇ，可实现质量分数ｗ（Ｏｓ）为９９．９９９９％锇粉中杂质元素测定。结合ＩＣＰ＿ＡＥＳ测定Ｋ、Ｎａ、Ｃａ、Ｍｇ、Ａｌ、Ｆｅ、Ｓｉ和Ｐ，可实现锇粉原料及产品的纯度分析。 相似文献