Study on Mechanical Properties of High-Performance Concrete

In this paper the high-performance concretes with 56-day compressive strengths of 60 to 100 MPa (with or without silica fume) have been studied experimentally in order to develop information about the mechanical properties of high-performance concrete. Results and discussions are presented regarding compressive strength gain with time,effect of drying. A linear equation of static modulus of elasticity has been derived.The static modulus of elasticity and Poisson's ratio are calculated by regression with testing data of 20 specimens.     

早稻品种对二化螟的抗性及其生化基础研究

】对二化螟在早籼５１４３和中１０６１与杂交早籼新香Ａ／７１和优ＩＡ／６６上造成的枯鞘、枯心数,及对不同品种稻株的总糖量和氨基酸总量测定及叶鞘组织硅质化分析,研究了水稻不同品种与二化螟的抗虫性关系。结果表明,虽未出现高抗二化螟的品种,但品种间对二化螟的耐虫性差别明显,中１０６１对二化螟的耐虫性最强,５１４３和新香Ａ／７１居中,优ＩＡ／６６最弱。二化螟在不同品种上的种群消长与糖含量具有一定相关性,糖含量高的品种二化螟发生程度重。硅化细胞多,硅质化程度高的品种对二化螟的抗性强。     

根据机动细胞硅酸体形态性状判别籼粳的研究

 以中国和亚洲其他国家的水稻地方品种和改良品种为材料,研究了机动细胞硅酸体的形态性状在籼、粳亚种间的差异。通过主成分分析和判别分析,探讨并建立了以硅酸体形态性状为指标的籼粳判别式,其判别效率可达90%左右,明显优于粒型判别法,与佐滕等提出的基于酚反应、氯酸钾抗性和稃毛长的判别结果基本一致。由于植物蛋白石具有残留量多和抗风化等优点,作者认为在籼、粳稻起源和分化的研究中,根据植物蛋白石的形态进行籼粳判别的方法比基于炭化米的粒型判别法更加有效。     

毛竹施用硅肥的效应研究

探讨了在有效硅含量水平较低的流纹岩风化物发育的土壤上，中、低产毛竹林施用硅肥的效应。试验结果表明，在中、低产毛竹林中施用硅肥是没有增产效果的；土壤中有效硅的含量管较低，但足够毛竹生长对硅素的需要。综合诊断施肥法（DRIS）对硅素营养的诊断结果提示，即使在具有较高竹材产量的竹林中，无论施用N、P、K三要素肥料与否，硅的营养况仍然是接近适宜水平的。鉴于中因大多数竹林的实际情况，认为目前生产上尚无施用硅肥的必要。     

Immobilization of the pesticide 2,4‐dichlorophenoxyacetic acid on a silica gel surface

A route for the immobilization of 2,4‐dichlorophenoxyacetic acid (2,4‐D) on silica gel has been developed. In the first step the precursor was prepared by reacting the silylating agent 3‐(trimethoxysilyl)propylamine with silica gel. Nitrogen analysis of this anchored compound showed the presence of 1.16 mmol of amine groups per gram of support. The herbicide was covalently bonded to the amine groups previously anchored onto silica gel. Infrared, [¹³C] and [²⁹Si] NMR spectra supported the reaction between the nitrogen of the amine group of the anchored silica with the carbon on the para‐position of the aromatic ring of 2,4‐D. The reaction yield, 90.3%, was confirmed through elemental analysis. © 2000 Society of Chemical Industry     

吡唑醚菌酯/二氧化硅微球的释放行为与生物活性评价

为了对二氧化硅载药体系进行评价,以吡唑醚菌酯为模式农药,利用其与正硅酸乙酯在碱性条件下的水解缩合反应,以十六烷基三甲基溴化铵(CTAB)为模板剂,制备了吡唑醚菌酯/二氧化硅微球。通过扫描电子显微镜、Nicolet iS5傅里叶变换红外光谱及高效液相色谱等表征了微球的表面形态和化学结构,测定了其在水中的光解速率;并采用透析袋法探讨了该微球在不同pH值和不同温度下的缓释行为,通过菌丝生长速率法测定了该微球对稻瘟病菌的毒力,评价了其生物活性。结果表明:所制备的吡唑醚菌酯/二氧化硅微球外观形貌较为规整,粒径在0.998~1.428 μm之间,其最大载药量可达50.73%。该微球在碱性条件下的释药速率快于酸性条件下,且其释放均符合一级反应动力学方程,在中性条件下其释药符合Ritger-Peppas方程;与pH值相比,温度对其释药速率的影响较小。给药后第5天,所制备吡唑醚菌酯/二氧化硅微球的毒力与原药相近,给药后第9天,其毒力是原药的11.7倍,缓释效果显著。该吡唑醚菌酯/二氧化硅微球在紫外灯照射10 h后光解率为38.98%,明显低于吡唑醚菌酯原药的光解率(68.92%)。     

Adsorption of anionic surfactant (sodium dodecyl sulfate) on silica

The adsorption of an anionic surfactant sodium dodecyl sulfate (SDS) on a negatively charged silica was studied to provide a better understanding of surfactant adsorption phenomena in an electrostatic repulsion environment between surfactant and soil. The adsorption experiment was conducted under different electrolyte concentration and pH. Results indicated that adsorption happened with hydrophobic interaction, although electrostatic repulsion was generated between SDS and silica surface. The adsorption amount decreased with decreasing electrolyte concentration and increasing pH due to the increase of electrostatic repulsion. The influence of electric potential near the silica surface on the adsorption was confirmed with the modified Langmuir adsorption equation, 1-pK basic Stern model and zeta potential. Because silica is ubiquitous in soils and the water environment, the adsorption characteristics of an anionic surfactant is important when we consider the fate of an anionic surfactant in the environment. The result is also useful when considering the fate of agricultural chemicals which contain negative charge and hydrophobic sites.     

辐解产物2-十二烷基环丁酮的测定方法

 【目的】建立1种含脂辐照食品中特异性辐解产物2－十二烷基环丁酮的萃取分离以及定量分析的新方法。【方法】采用硅胶层析柱萃取分离、气相色谱－质谱联用检测,对淋洗剂浓度、硅胶活化程度、收集时间及气相色谱-质谱条件等技术参数进行优化。【结果】该方法对2－十二烷基环丁酮标准品的最低检出限为0.005 mg?L-1,0.1～2.0 mg?L-1的添加回收率为75.9%～103.9%,相对标准偏差（RSD）均小于5.7%。【结论】与欧盟标准方法EN1785进行比较,硅胶柱分离法具有成本低、提取效率高、重现性好、检出限低、承载样品量大等优点。     

柴胡皂苷硅胶柱层析分离方法的研究

为探讨柴胡单体皂苷的分离条件,采用超声波提取,正丁醇萃取,硅胶GH柱层析分离,层析检测方法。结果表明乙酸乙酯：95%乙醇（8：2）分离出三个单体化合物,说明硅胶柱层析可用于柴胡皂苷的制备性分离。     

介孔活性炭阿维菌素载药系统的性能研究

研究了介孔活性炭对阿维菌素的载药特性,以判断其作为阿维菌素载体的可能性。以扫描电子显微镜、比表面积分析仪和粒度分析仪对其进行了物理性状表征。将其负载阿维菌素的能力与常规农药载体进行比较,并进一步分析和评价了该载药系统的吸附动力学特性、缓-控释性能和抗紫外光降解能力。结果表明:供试活性炭载体为不规则球形颗粒状介孔材料,平均粒径为814 nm,比表面积为1 719.25 cm2/g,孔容积为0.043 cm3/g,孔径为4.80 nm。吸收动力学数据符合伪二级动力学模型,对阿维菌素的载药量为220.6 mg/g,显著高于其他常规农药载体,呈现了优良的吸附性能;载药系统的释药时间从90 h延长到672 h以上,表现出了良好的缓释效果;紫外光照射72 h后,阿维菌素原药的分解率为77%,而有活性炭载体保护的阿维菌素的分解率为30% ,表明该载药系统有效地减缓了阿维菌素的光降解速率。研究表明,以介孔活性炭作为阿维菌素载体,可显著改善药物的缓-控释特性以及分散性和光稳定性。