非对称扰动下热轧铝带跑偏过程三维数值模拟

基于大型工程分析软件MSC.Marc，设计了模拟Fi机架轧制过程的三维有限元模型，结合实验研究得到的1235铝合金高温本构方程，模拟出非对称性扰动下,热轧铝合金板带跑偏状态；研究了板带在来料厚度分布横向非对称、辊缝形状横向非对称及来料不对中扰动下，轧制力、板带运动轨迹等轧制参数的横向非对称性；探讨了板带跑偏与轧制力、压下率等轧制参数的横向分布特征的相关性.研究结果表明：不同扰动下板带的跑偏方向与两侧轧制力差的关系并不一致，不能根据轧制力差判断板带的跑偏方向；压下率差与跑偏方向具有一致性，板带由压下率大的一边向压下率小的一边跑偏，这一规律为无法明确扰动的板带纠偏策略提供了理论参考.     

2.25Cr-1Mo与铁铝合金高温抗氧化性能的对比研究

对2．25Cr-10钢与铁铝合金的高温抗氧化性能进行了对比研究。铁铝合金具有许多性能上的优点，尤其在其高温抗氧化性能方面。明显优于不锈钢、铬钼钢等传统的高温结构材料，并且随着温度的升高及铝含量的增加，其优势更加显著。     

苏打盐碱土结构性与持水特性的改良研究

采用硫酸铝对吉林省西部苏打盐碱土进行了改良,对改良后土壤的结构性及持水特性进行了测定。结果表明,施用硫酸铝后苏打盐碱土的土壤结构性与持水特性均有显著改善,土壤团聚体(>0.005 mm)的数量显著增加。当硫酸铝用量达0.4%(质量分数)时,土壤容重由1.35 g/cm3降至1.16 g/cm3,孔隙度由49.1%增至56.2%。随着硫酸铝用量的增加,膨胀度增大,土壤渗透性和持水能力增强。     

铝胁迫下根系分泌物对栝楼光合特性及耐铝性的影响

以耐铝性较强的安国栝楼和耐铝性较弱的浦江栝楼为对比试验材料,在土培条件下探究300μmol/L和800μmol/L铝胁迫下不同浓度(30,20,10ml/株)根系分泌物对2种栝楼的生长特性、光合特性和抗氧化酶活性的影响。结果表明,经过2个浓度的铝处理后,安国栝楼和浦江栝楼生长均受到一定抑制,生物量、叶绿素a/b含量、叶绿素荧光、CAT、POD、SOD酶活性均呈下降趋势,而MDA、初始荧光(F_0)呈相反的变化趋势,2种栝楼的各指标变化程度和敏感性表现出一定的差异性,表明2种栝楼的耐铝性存在差异。加入适宜浓度的根系分泌物能够促进2种栝楼的生长,提高叶绿素a、b含量以及各个荧光参数值和CAT、POD、SOD等抗氧化酶活性,从而缓解了铝胁迫。较低浓度的根系分泌物可以缓解铝胁迫对栝楼的伤害;浓度过高时,2种栝楼的生长均会受到抑制,20ml/株的根系分泌物对栝楼铝胁迫的缓解作用最佳。因此,今后在红壤地区栝楼的生产种植中,可以进一步开展根系分泌物对栝楼影响机制的研究工作,为栝楼品种的推广与应用奠定基础。     

低分子量有机酸对促进可变电荷土壤中铝溶解的影响

Low-molecular-weight （LMW） organic acids exist widely in soils and play an important role in soil processes such as mineral weathering, nutrient mobilization and A1 detoxification. In this research, a batch experiment was conducted to examine the effects of LMW organic acids on dissolution of aluminum in two variably charged soils, an Ultisol and an Oxisol. The results showed that the LMW organic acids enhanced the dissolution of A1 in the two investigated soils in the following order： citric 〉 oxalic 〉 malonic 〉 malic 〉 tartaric 〉 salicylic 〉 lactic 〉 maleic. This was generally in agreement with the magnitude of the stability constants for the Al-organic complexes. The effects of LMW organic acids on Al dissolution were greater in the Ultisol than in the Oxisol as compared to their controls. Also, the accelerating effects of citric and oxalic acids on dissolution of A1 increased with an increase in pH, while the effects of lactic and salicylic acids decreased. Additionally, when the organic acid concentration was less than 0.2 mmol L-I, the dissolution of A1 changed Iittle with increase in acid concentration. However, when the organic acid concentration was greater than 0.2 mmol L^-1,the dissolution of A1 increased with increase in acid concentration. In addition to the acid first dissociation constant and stability constant of Al-organic complexes, the promoting effects of LMW organic acids on dissolution of A1 were also related to their sorption-desorption equilibrium in the soils.     

Boron-Calcium Synergically Alleviates Aluminum Toxicity in Wheat Plants (Triticum aestivum L.)

The effects of B and Ca treatments on root growth, nutrient localization and cell wall properties in wheat ( Triticum aestivum L.) plants with and without Al stress were investigated. Seedlings were grown hydroponically in a complete nutrient solution for 7 d and then treated with B (0, 40 μM), Ca (0, 2,500 μM), and Al (0, 100 μM) in a 500 μM CaCl₂ solution for 8 d. The cell wall materials (CWM) were extracted with a phenol: acetic acid: water (2:1:1 w/v/v) solution and used for subsequent pectin extraction with trans -1,2-diami-nocyclohexane- N,N,N,N -tetraacetic acid (CDTA) and Na₂CO₃ solutions. Boron, Ca, and B + Ca treatments enhanced root growth by 19.5, 15.2, and 27.2%, respectively, compared to the control (pH 4.5). Calcium and B+Ca treatments enhanced root growth with Al stress by 43 and 54%, respectively, while B did not exert any effect. The amounts of CWM and pectin per unit of root fresh weight increased by Al treatment, whereas the Ca and B+Ca treatments slightly reduced the contents of these components. Seventy-four percent of total B, 69% of total Ca, and 85% of total Al were located in the cell wall in the B, Ca, and Al treatments, respectively and 32% of total B, 33% of total Ca, and 33% of total Al were located in the CDTA-soluble and Na₂CO₃-soluble pectin fractions. A more conspicuous localization of B was observed in the presence of Al. Aluminum treatment markedly decreased the Ca content in the cell wall as well as pectin fractions, mainly in the case of the CDTA-soluble pectin fraction. Boron + Ca treatment decreased the Al content in the cell wall and pectin fractions compared to the Ca treatment alone in the presence of Al. It is concluded that the B+Ca treatment enhanced root growth and, B and Ca uptake, and helped to maintain a normal B and Ca metabolism in the cell walls even in the presence of Al.     

Growth Characteristics of Tea Plants and Tea Fields in Japan

In 12th century, the Buddhist priest Eisai brought tea ( Camellia sinensis L.) seeds to Japan from China and now tea plants are cultivated all over Japan except in the Hokkaido and Tohoku districts. The quality (reflected in the price) of Japanese green tea is affected by the nitrogen content. Consequently in tea fields, for last three decades large amounts of fertilizer have been applied to produce high quality tea. As a result, problems such as acidification of soil have been caused. It is also known that the growth of tea plants is stimulated by the addition of aluminum (Al) under acidic conditions. In this keynote address, some problems caused by excess applications of fertilizer in tea fields and the growth characteristics of tea plants related to Al are presented.     

铝、氟及其复合处理对茶树根际土壤酶活性的影响

研究了铝、氟及其交互作用对白茶和智仁早茶根际土壤酶的生态效应。结果表明,在单独施铝处理中,脲酶和多酚氧化酶活性受到抑制,其它土壤酶活性均随铝浓度的升高呈现先升后降的趋势,当Al浓度高达400mg/kg时,对酶呈现出抑制作用,影响达显著或极显著水平;在单独氟处理下,磷酸酶、尿酸酶活性变化不大,随着氟浓度的升高,除多酚氧化酶活性受抑制外,其余的酶活性也呈现出先升后降的趋势,当F浓度高达120 mg/kg时,对酶产生抑制作用,总体上氟的影响不如铝显著;铝、氟复合处理条件下,铝与氟之间联合作用对脲酶、蛋白酶、过氧化物酶、过氧化氢酶、多酚氧化酶、尿酸酶和抗坏血酸氧化酶活性产生了显著或极显著的交互效应,其作用方式因铝、氟处理浓度组合、酶及茶树品种的不同而不同。研究还发现,铝、氟对茶树根际土壤酶的交互效应与铝氟浓度的比值有密切关系,且不同的酶活性达最高时的铝氟比值基本相同,表明在茶树体内代谢中铝、氟之间存在一定的相关性。根际土壤酶活性在两个茶树品种间存在较大的基因型差异,尤其以酸性磷酸酶和抗坏血酸氧化酶最为显著,总体上白茶根际土壤酶对铝、氟及其交互作用较智仁早茶更敏感,两茶树品种之间土壤酶活性的差异与茶树根际过程密切相关。     

酸铝胁迫下4个速生桉优良无性系的生长反应

采用砂土培育法研究不同的酸铝处理对几种桉树优良无性系（巨尾桉9号、巨尾桉12号、尾叶桉4号、韦赤桉3号）幼苗生长及膜透性等变化的影响。试验设: pH 3.0＋0 mg/L Al3+、 pH 3.0＋120 mg/L Al3+、 pH 4.0＋0 mg/L Al3+、 pH 4.0＋120 mg/L Al3+、 pH 4.8＋0 mg/L Al3+5个处理。结果表明,不同酸铝处理对4个桉树优良无性系形态、生长指标、含水率、叶绿素含量、质膜透性和脯氨酸含量等都产生不同的影响。与对照（pH 4.8＋0 mg/L Al3+）相比,pH 3.0＋120 mg/L Al3+处理对桉树幼苗的生长产生的抑制作用明显,叶、芽皱缩、变形,苗高、地径以及各器官含水率降低,质膜透性和叶绿素含量下降,桉树幼苗累积较多的脯氨酸。其中,巨尾桉广林9号对酸铝逆境的抗性优于其它3个无性系。4个桉树优良无性系抗酸铝逆境的能力强弱依次为: 巨尾桉9号巨尾桉12号 韦赤桉3号尾叶桉4号。因此,选育耐酸铝桉树无性系品系是改善南方富铝化酸性土壤林地生产力的重要策略之一。     

铝胁迫对酸性红壤中真菌种群多样性的影响

通过聚合酶链式反应-限制性片段长度多态(PCR-RFLP)技术构建了红壤真菌的内转录间隔区(Internal Transcribed Spacer,ITS)rDNAs文库,比较分析了红壤地区典型森林土和农田土真菌群落结构对铝胁迫的响应,构建了6个土壤样品的真菌ITS rDNAs文库。从这6个克隆文库中随机挑取克隆进行了PCR-RFLP指纹图谱分析,共获得77个独特的真菌操作分类单元(OperationalTaxanomicalUints,OTUs)。对77个OTUs的代表性克隆测序并利用Blast工具进行分析(相似性95%~100%)。研究结果表明森林土壤和农田土壤样品中真菌类群79.2%(61)属于子囊菌门(Ascomycota)、担子菌门(Basidiomycota)和球囊菌门(Glomeromycota),20.8%(16)属于未分类的簇(Unclassifiedfungi),其中担子菌门真菌在两种土壤中具有明显优势。物种多样性指数(Simpson、Shannon和Chao1)分析表明,铝胁迫降低了土壤真菌种群的多样性,农田土壤中真菌的种群多样性明显高于森林土壤。而且随着铝胁迫浓度的增加,担子菌门真菌在两种土壤中丰度明显下降,子囊菌门真菌的丰度显著上升,在高铝处理浓度处理的土壤中演变为优势种群。