Effect of the Silicic Acid Polymerization Degree on the Coagulating Property of Polyalumium Silicate Chloride

Polyaluminum silicate is a new type of inorganic macromolecular flocculants, which is developed as a complex product in recent years on the base of polyalumium flocculant and polysilicic acid flocculant. Sodium silicate is diluted to the concentration of 3.0% SiO 2 with distilled water. The solution was adjusted to pH 4.5 with sulphate acid and kept at quiescency for different time to get polysilicic acid with different polymerization degrees. Using polysilicic acid prepared and aluminium chloride as materials, a series of polyaluminium silicate chlorides(PASC) with different basicities(B), Al/Si molar ratios and polymerization degree of silicic acid are prepared by copolymerization technique. The Al-Ferron timed complex colorimetric method is applied to characterize species distribution of PASC and to study its influence factors. The interaction between hydrolyzed aluminum species and polysilicic acid with different polymerization degrees in PASC is discussed.The flocculant prepared is applied to the treatment of commercial concrete wastewater. The turbidity removal of commercial concrete wastewater is up to 97% when a PASC, prepared with polysilicic acid of 145 min polymerization degree.     

Abscisic acid, gibberellin and cell viability in cereal aleurone

The aleurone layer of cereals is a secretory tissue whose activity is regulated by abscisic acid (ABA) and gibberellins (GAs). Whereas GA triggers enzyme synthesis and secretion and initiates a program that culminates in cell death, ABA prevents enzyme production and cell death. Reactive oxygen species (ROS) are key players in regulating cell viability and GA sensitizes the aleurone cell to ROS. Sensitivity of GA-treated cells results in part from a reduction in steady-state amounts of mRNAs encoding enzymes that scavenge ROS. mRNAs encoding catalase, superoxide dismutase and ascorbate peroxidase are almost undetectable in aleurone layers 24 h after incubation in GA. For layers incubated in ABA, however, the amounts of these mRNAs increase. Western blotting and enzyme activity assays confirm that GA but not ABA reduced the amount and activity of ROS scavenging enzymes (Fath et al., 2001b). Substantial amounts of ROS are produced by enzymes engaged in lipid metabolism, and by the electron transport chain in the mitochondria. Aleurone layers contain abundant stores of triglycerides and ROS are produced as these lipids are rapidly converted to sugars. We hypothesize that the ROS produced in GA-treated aleurone cells bring about cell death by disrupting the plasma membrane. Aleurone cells incubated in ABA, on the other hand, are better able to maintain redox balance. ABA does not initiate rapid triglyceride metabolism, and the activities of ROS-scavenging enzymes remain high in ABA-treated cells. We conclude that GA initiates a metabolic cascade in aleurone cells that results in death from ROS. ABA maintains viability by keeping ROS under control. This revised version was published online in August 2006 with corrections to the Cover Date.     

不同水分,温度条件下CO2浓度对大米品质的影响

试验选用当年新收获的稻谷加工成的水分为１３．９％、１４．７％和１６．０％的大米，在２３℃和３３℃的恒温室中，将７种不同浓度的ＣＯ２经减压调湿后通入粮堆。定期取样，测定大米的脂肪酸、水溶酸、还原糖、非还原糖、粘度和过氧化物酶活性的变化。试验结果表明：１３．９％水分的大米在２３℃下储藏，各种浓度ＣＯ２对大部分品质指标影响不显著，ＣＯ２的保质作用不明显；１４．７％水分的大米在２３℃储藏，ＣＯ２对个别品质     

生菜切块充气贮藏条件的研究

用23种不同的充气条件研究生菜切块的贮藏效果,通过感官质量评价和化学分析,观察颜色的变化、褐变程度及维生素C和叶绿素含量的差异,结果表明,采用O_2 20％+CO_240％+N_2 40％的贮藏条件是比较合适的.在上述条件及5℃的情况下,生菜切块的有效贮藏期大约在12～15d之间,这一结果在商业上有一定的实用价值.     

棱角山矾种子的休眠与萌发初探

棱角山矾种壳占种子风干重90.19%,种子透水性良好.浓硫酸处理1.5小时后,可使种壳减轻9.48%.硫酸处理增强了种子的透气性并减弱了种壳机械束缚力.添加500mg·L-1GA3溶液,经过1～5 ℃16h及20 ℃8h变温砂藏三个月后,可获得44%出苗率,而对照种子则颗粒不发.     

苹果酸处理水稻种子对秧苗根系及抗寒性影响的初探

水稻种子经苹果酸处理后,淀粉酶过氧化氢酶和脱氢酶活性均有提高。其幼苗根系发达,根/茎叶比重增加。幼苗经5C冷处理后,超氧化物歧化酶活性和叶绿素含量虽表现出下降,但明显高于对照。丙二醛含量和电解质渗漏率比对照为低。苹果酸处理在一定程度上提高了水稻秧苗素质及抗寒能力。     

人参胚后熟期间核酸、蛋白质、糖的变化及激素的影响

人参种子需经形态后熟和生理后熟才能萌发。在整个胚后熟期间,每粒种子总核酸、RNA量逐渐增加,DNA含量逐渐下降、类脂、总糖,淀粉含量也逐渐下降,胚缓慢增长。经激素处理后、总核酸,RNA量在形态后熟阶段快速增加,胚率迅速增长。在生理后熟期,出现一个淀粉的含量高峰,随后出现一个还原性糖的含量高峰,因此,认为生理后熟的作用可能是为种子萌发积累能量。     

Effects of Salicylic Acid on the Development and Root Nodulation of Soybean Seedlings

Salicylic acid (SA) is recognized as an endogenous regulator of plant metabolism, mainly involved in induction of systemic acquired resistance (SAR). Exogenous SA can also induce a SAR reaction and SAR gene expression. Excessive SAR-related activity can be an overall cost to the plant in terms of energy and materials expended unnecessarily. Elicitation of plant defence responses might also block beneficial plant-microbe interactions and result in negative effects on plant growth. The objective of this study was to investigate the effects of SA concentration (5, 1, 0.5, 0.1 and 0 m m ) on soybean seedling growth and nodulation by watering of soybean seedling roots or soaking of seedling leaves with SA solutions. It was found that 5 m m SA had negative effects on soybean seedling development, but other concentrations of SA did not affect the development of soybean seedlings. In addition, there were no negative effects on seedling development due to SA soaking of seedling leaves. Soybean seedling growth in sterile soil was reduced due to repressed nitrogen uptake following addition of 5 m m SA, indicating that some concentrations of SA can alter the N nutrition of seedlings. A model is presented that ties SA to nodule formation and plant growth.     

Physiological and Biochemical Responses of Hexaploid and Tetraploid Wheat to Drought Stress

An experiment was conducted to investigate the physiological and biochemical responses of two hexaploids viz., C 306 (water stress tolerant) and Hira (water stress susceptible), and two tetraploids, HW 24 (Triticum dicoccum) and A 9‐30‐1 (Triticum durum) wheat genotypes to water stress under pot culture condition. Water stress was imposed for a uniform period of 10 days at 50, 60 and 70 days after sowing (DAS) and observations were recorded at 60, 70 and 80 DAS. Total dry matter and plant height were recorded at harvest. Water stress caused a decline in relative water content (RWC), chlorophyll and carotenoid content, membrane stability and nitrate reductase activity and increased accumulation of proline at all stages and abscisic acid (ABA) at 80 DAS in all the genotypes. Both the tetraploids showed a lower reduction in RWC and highest ABA accumulation under water stress. Among the hexaploids Hira showed the most decline in RWC and the lowest ABA accumulation. The tetraploids also showed comparatively higher carotenoid content and membrane stability, closely followed by C 306, while Hira showed the minimum response under water stress. Nitrate reductase activity and chlorophyll content under irrigated conditions were highest in Hira but under water stress the lowest per cent decline was observed in C 306, followed by HW 24, A 9‐30‐1, and Hira. Proline accumulation under water stress conditions was highest in hexaploids C 306 and Hira and lowest in tetraploids HW 24 and A 9‐30‐1. Tetraploids HW 24, followed by A 9‐30‐1 maintained higher plant height and total dry matter (TDM) under water stress and also showed a lower per cent decline under stress than hexaploids C 306 and Hira. From the results it is clear that proline accumulation did not contribute to better drought tolerance of tetraploids than hexaploids. It is also apparent that water stress tolerance is the result of the cumulative action of various physiological processes, and all the parameters/processes may not be positively associated with the drought tolerance of a particular tolerant genotype.     

石榴发酵酸乳研制

将石榴汁引入酸奶中,研制富含保健功效石榴发酵酸乳.最佳工艺条件为石榴汁与牛奶配比1:5,砂糖加入量为8.0%,CMC添加量为0.06%.