混凝土微波促凝技术的试验研究

为了快速预测普通混凝土和掺入硅粉的高性能混凝土的早期强度,增强对混凝土后期强度的控制,进行微波促凝混凝土试验。本试验采用微波加热混凝土的方法,对不同混凝土的促凝机制的试验研究。最后得出最优的微波加热制度,这种微波加热制度使普通混凝土和加入硅粉的高性能混凝土5~6h强度达到28d强度的10%左右。试验表明,采用有效的微波加热的方法,可以提高掺入硅粉的高性能混凝土的早期强度。     

不同利用方式棕壤的铝硅氧化物的分异特征

棕壤是我国重要的土壤资源,其特殊的气候地形条件决定了必须科学合理的开发利用才能保证该地区农业的可持续发展。本文对林地、蚕地、耕地3种利用方式下棕壤中铝硅氧化物的变化情况进行了研究。结果表明:(1)不同利用方式下,铝氧化物的无定形态在各层间差异较大。0~20 cm土层的游离硅、无定形铝均表现出随人为干预程度的提高而增加的趋势,反映出开垦的集约化加剧了土壤的风化作用。(2)从各形态氧化物在剖面间的分布来看,游离氧化硅、无定形铝的分布均呈向下富集的趋势,与粘粒在土体内的分布规律一致。活性硅与不同利用方式土壤的风化淋溶作用关系的规律性不明显,但可反映作物对硅的吸收特性。(3)开垦后土壤表层生物积累量的减少,影响了土壤表层活性硅的积累。     

浅谈稻壳的综合利用与开发

阐述了稻壳资源化利用的途径与方法。稻壳的主要成分是纤维素、木质素和二氧化硅。其纤维素可用于制造木糖醇、糠醛、饲料和肥料等;二氧化硅可用于制造高纯二氧化硅、水玻璃和电池材料;利用它的碳、氢元素,通过热解来获得能源。科学开发与利用稻壳,是保护环境,消除白色污染,发展新能源的有效途径。     

几种木材中硅石的研究

要实现木材-无机质复合材的人工模拟,其关键还是在于研究和探讨木材生物矿化的机理,因此要对木材中无机物的情况进行研究,从而获取生物矿化所形成的木材/无机质复合材料的形成机理,以此来指导木材的生物改性或木材/无机复合材的仿生合成。本文采用光学显微镜对几种木材/二氧化硅生物矿化复合材中硅石的分布进行观察发现:硅石主要分布在木射线细胞中,大量的晶体在木射线细胞以及轴向薄壁细胞中均有分布;采用重量法对几种木材/二氧化硅生物矿化复合材中二氧化硅含量情况进行测定表明:子京、山油柑、柚木、柠檬桉、山竹子等5种木材/二氧化硅生物矿化复合材中二氧化硅含量分别为1.5106%、0.8941%、0.8654%、0.2155%、0.1676%。     

不同方法对枣叶片总DNA提取效果的影响

以串杆枣的成熟鲜叶为试材,分别采用-20℃、-70℃和硅胶脱水干燥3种方法保存样品,采用简易CTAB法、高盐沉淀法与高盐低pH值法分别对3种方法保存的样品及对照样(鲜叶)进行了基因组DNA提取效果的比较分析。结果表明,3种方法均能有效地从枣叶片中获得质量较高的DNA,以高盐沉淀法所得的DNA纯度最高,高盐低pH值法次之。就DNA的产量而言,高盐沉淀法的DNA产量相对较低,低于其他的2种方法,但未达到显著水平。硅胶干燥法和-70℃超低温保存的样品与鲜叶相比,所提DNA的质量和产量均无明显差异,均能满足PCR扩增要求。硅胶保存法适于野外远距离采样。     

玉米淀粉树脂基砂轮片的制备与表征

以淀粉、糠醛与甲醛共缩聚合成淀粉基树脂为基质,二氧化硅颗粒为研磨材料制备新型天然可再生生物质砂轮片,分析了淀粉基树脂的主要化学结构、黏度和凝胶时间及砂轮片的微观形态和力学性能。结果表明：淀粉、糠醛与甲醛在弱酸性条件下发生了共缩聚反应,该淀粉基树脂的玻璃化转变温度较纯淀粉树脂高。用该树脂制备的砂轮片的硬度高于自制酚醛树脂砂轮片,且该生物质树脂基砂轮片的切割性能与自制酚醛树脂砂轮片相近。因此,未来用该砂轮片替代部分酚醛树脂基砂轮片是可行的。     

Estimating Sorption Affinities of Heavy Metals on Humic Acid and Silica using a Constant Capacitance Model

The adsorption of heavy metals [cadmium (Cd ²⁺), cobalt (Co²⁺), nickel (Ni²⁺), zinc (Zn²⁺), and lead (Pb)] and calcium (Ca²⁺) on humic acid and silica were investigated to understand the adsorptive selectivities of heavy metals on the constituents of soil. The experiments for the adsorption of Cd and Pb were carried out in a 0.1 mol L^?1 (M) sodium nitrate (NaNO₃) background solution, whereas those for the other metals were done in a 0.1 M sodium chloride (NaCl) solution. The adsorptive affinities of the metal ions on the humic acid and silica were ranked by the intrinsic surface complexation constants [K _m ¹(int)] that were calculated approximately from the adsorptive data using a constant capacitance model. The log [K _m ¹(int)] values of the metals were in the order Zn²⁺(?2.29) > Cd²⁺(?2.41) > Co²⁺(?2.74) > Ni²⁺(?2.92) ?> Ca²⁺ (?3.33) for the humic acid and Zn²⁺(?4.23) > Cd²⁺(?4.49) > Ni²⁺(?4.51) ? Co²⁺ (?5.99) > Ca²⁺(?6.37) for silica.     

水稻叶表皮硅体显微结构及其分布

在前期探讨水稻硅质化对稻草降解利用的阻碍关系基础上,利用扫描电镜比较了汕优63、谷秆两用水稻201、低纤维基因突变体嫩稻和其亲本的叶表皮硅质化细胞显微结构与分布.观察发现:不同水稻品种叶片上表皮硅细胞排列除致密程度略显差异,形状变化趋向一致;角质—硅—蜡层上分布着沉积形成的硅质化大分子不可溶的晶体结构,与气孔周边排列的硅质化爪状突起一样,可能与气孔水分蒸腾后的硅化物沉积有关.     

大熊猫粪便DNA纯化及其PCR检测

建立了二氧化硅法纯化大熊猫粪便中DNA的技术 ,所得DNA可用于PCR扩增 ,而传统的有机溶剂提取的DNA不能去除粪便中抑制PCR反应的成分 ,使扩增结果呈假阴性。     

Effects of Rice Straw Silicification and Characters of Extraction Biogenic Silicon on the Degradation of Fibrous Components in Rice Straw

Straw of seven rice varieties with early-, middle- and late maturity was collected from Huazhong Agricultural University in Hubei. A study was carried ont for rice straw in the aspects of the characters of straw silicification and extraction biogenic silica (EBSi), the relationship between characters of EBSi and kinetic characteristics of degradation of fibrous components in fistulated cows, as well as the effect of urea treatment on rice straw desilicification. Although total silica content (ADISi) in rice straw was similar, the efficiency of extraction biogenic silica (EEBSi) and cellulose in early varieties were significantly higher than those in middle (18.9% and 9.1%) and late ones (26.1% and 11.2%). The degradability of EBSi and cellulose of early varieties were higher than those of middle by 70.0% and 17.5%, and of late varieties by 47.8% and 23.7%, respectively. The in sacco degradability and in vitro VFA production of early varieties were also higher than those of middle by 14.5% and 19.0%, and late by 12.9% and 14.8%.Comparing the morphological fractions of the rice straws, EEBSi, cellulose content, and in vitro VFA production were different with the order of blade ＜ sheath ＜ stem. A significant correlation was found between the contents of EBSi and cellulose (r = 0.86), and the two contents were remarkably correlated with the potential straw degradability (a + b) by r = 0.90 and 0.84 respectively. Therefore, EBSi in rice straw was a main factor affecting the potential degradability of rice straw, rather than the ADISi of straw. Urea treatment improved rice straw degradability, degradation rate and potential degradability by 10.8%, 27.9%,and 10.1% respectively, compared to untreated straws.