β-甘露聚糖酶理化性质与其最适pH的相关性

为了探究影响GH5家族β-甘露聚糖酶最适pH的各种因素,利用该酶的序列信息,构建了基于氨基酸组成的β-甘露聚糖酶理化性质与其最适pH的相关性模型。结果表明:该酶N端氨基酸序列是影响其最适pH的重要因素,在243个理化性质中有17个呈极显著相关,其中7个呈正相关。优化的转移能量参数相关性最高,为0.78:7个正相关的理化性质中,与螺旋相关的理化性质占3个。优化的转移能量参数和螺旋是影响pH稳定性的最重要的因素。所建立的模型为研究该酶酸碱适应性机理提供了一种简单有效的方法。     

Effects of urea fertigation of apple trees on soil pH,exchangeable cations and extractable manganese in a sandy loam soil in New Zealand

Changes in soil pH, exchangeable aluminium (Al), calcium (Ca), magnesium (Mg), and potassium (K) and extractable manganese (Mn) were investigated after urea fertigation of a sandy loam soil in an apple orchard in New Zealand. Urea at three rates (0, 25, 50 kg N ha^–1 yr^–1 or 0, 16.9, 33.8 g N emitter^–1 yr^–1) was applied in 4 equal fertigations. Soil cores at 4 profile depths (0–10, 10–20, 20–40 and 40–60 cm) directly below and 20 cm from the emitter were sampled approximately 4 weeks after each fertigation and in the following winter. Results obtained showed that the largest changes in soil pH and cations occurred in soils directly below the emitter in the 50 kg N ha^–1 yr^–1 treatment where the soil pH decreased by 1.6 pH units at all soil depths. The lowest pH of 4.3 was observed at a depth of 27 cm. Exchangeable Al and extractable Mn levels increased to 11 meq kg^–1 and 78µg g^–1 respectively. Estimated losses of Ca, Mg and K from the upper soil profile depth (0–10 cm) represented 23, 63 and 27% of their respective total exchangeable levels. At lower profile depths (>20 cm), accumulation of displaced K was evident. Variable, and generally non-significant, chemical changes recorded in soils 20 cm from the emitter were attributed to restricted lateral water movement, and therefore urea movement, down the profile.The present study showed that one season of urea fertigation by trickle emitters, applied to a sandy loam, at half the rate conventionally applied to apple orchards (50 kg N ha^–1 yr^–1) resulted in pH and mineral element imbalances which were potentially and sufficiently severe to inhibit tree growth.     

基于CRFs模型的敏感话题识别研究

条件随机场（CRFs）是一种判别式概率无向图学习模型,将其引入敏感话题识别中,提出了基于CRFs模型的敏感话题识别方法。将随机挑选出的一篇待检测文本s和剩余的待检测文本分别作为CRFs模型的观察序列和状态序列来计算文本s和其余待检测文本间的相关性概率值;然后将相关性最高的那篇文本和文本s合并表征一个类别;同时,将相关性最低的那篇文本作为另一个类别,将这两个类别作为CRFs模型新的状态序列,剩余的待检测文本作为新的观察序列进行迭代,据此实现敏感话题的识别。在数据集上进行的实验中,该方法的耗费函数的值为0.01943,宏平均F度量的值为0.8235,都取得了很好的效果。     

锌溴液流电池安全性研究

针对锌溴液流电池电解液中溴易挥发,充电过充时以及充电过程中温度过高易造成安全性隐患,通过对溴络合剂,电氧化聚合电解液添加剂,电压敏感隔膜,温度敏感电极等,这些影响因素进行实验分析,结果表明溴络合剂采用四丁基溴化铵,电氧化聚合电解液添加剂采用4-溴苄基异氰酸酯,电压敏感隔膜采用聚对苯和聚二苯胺复合膜,温度敏感电极采用环氧树脂-炭黑复合物的PTC材料,就能很好的控制锌溴液流电池的安全性。     

临界组成区域的热敏导电材料加工工艺

研究了开炼，密炼及双螺杆挤出３种不同塑炼方式及采用压制，注射，单螺杆挤出３种不同成型方法对临界组成区域的热敏导电材料电性能及力学性能的影响规律，并对开炼，密炼两种工艺的混炼条件，加料方式及加料顺序进行了考察，结果表明，采用密炼工艺，炭黑（ＣＢ）粒子能得到均匀分布，电阻率较低，拉伸强度及断裂伸长率高，适中的剪切速率及温度有利于ＣＢ粒子分散，采用压制成型法所得样品各向同性。     

聚苯胺/沸石分子筛复合材料的湿敏特性研究

酸化的聚苯胺是一种很有应用前途的感湿材料,沸石分子筛具有离子交换作用和较大比表面积的优良特性。将沸石分子筛与聚苯胺复合,可以增强聚苯胺的吸湿能力和载流子的移动性,进而改良感湿特性。利用结构导向剂法合成了沸石分子筛,与酸化的聚苯胺复合,并测量复合材料的感湿特性。与纯的聚苯胺相比,复合材料在低湿范围内有更好的灵敏度。     

Electrochemical copolymerization of aniline with m-aminophenol and novel electrical properties of the copolymer in the wide pH range

A copolymer, poly(aniline-co-m-aminophenol), has been synthesized using repeated potential cycling. The monomer concentration ratio, acid concentration and applied potential strongly affect the copolymerization rate and the properties of the copolymer. The optimum conditions for the copolymerization are that the scan potential range is controlled between −0.10 and 0.95 V (vs.SCE), and a solution consists of 0.34 M aniline, 0.012 M m-aminophenol and 2 M H₂SO₄. The IR spectra of the copolymers demonstrate that the m-aminophenol units are included in the copolymer chains. The cyclic voltammograms of the copolymers in 0.3 M Na₂SO₄ solution with various pH values were performed at the potential ranges from −0.20 to 0.80 V and at a scan rate of 60 mV s⁻¹. The results indicate that the copolymer still hold 41.7% of the electrochemical activity when the copolymer electrode was transferred from a solution of pH 5.0 to a solution of pH 11.0 in the potential range of −0.20 to 0.80 V. An impedance plot of the copolymer in a solution with pH 12.0 and at 0.40 V is constructed of a semicircle and a Warburg line with a slope of 1. This means that the electrode reaction of the copolymer at pH 12.0 is also under mass transfer control. The conductivity of the copolymer prepared under the optimum conditions is 1.42 S cm⁻¹, and slightly depends on the pH value. Thus, the pH dependence of the electrical properties of the copolymer is improved compared with poly(aniline-co-o-aminophenol), and is much better than that of the parent polyaniline.     

无苯溶剂型三元共聚丙烯酸酯类压敏胶的研制

以丙烯酸丁酯(BA)、醋酸乙烯(VAc)、丙烯酸(AA)为原料,乙酸乙酯为溶剂,过氧化苯甲酰为引发剂对三元共聚丙烯酸酯类压敏胶进行了研究,考察了引发剂的用量与加入方式、单体配比、AA用量、反应温度和反应时间对压敏胶性能的影响;得出了最佳的工艺条件为,引发剂采取分批加入方式、用量为0．45％,AA用量4．3％,V(BA)／V(VAc)为60:9,反应温度84℃,反应时间为8 h;制得了初粘力14(球号)、持粘力>24 h、180°剥离强度达15．33 N·(25mm)-1的具有优良综合性能的压敏胶。     

Shear Strength of Pressure Sensitive Adhesives and its Correlation to Mechanical Properties

Correlations between shear resistance and the mechanical properties of pressure sensitive adhesives are studied by measuring the deformation behaviour in the static and the dynamic shear test and determining the dynamic shear modulus of the adhesive. For polymers with low or moderate viscosities, the shear strain vs. time characteristics in a static shear test and, accordingly, the static shear strength, can be evaluated from the master curves of the dynamic shear modulus or the dynamic viscosity. The dynamic shear strength also can be calculated. These exact calculations cannot be applied to highly viscous or slightly crosslinked polymers. On the basis of the model experiments, empirical correlations between shear strength and the dynamic shear modulus are established which seem to be generally valid.     

化纤综合废水处理絮凝剂的筛选与应用

分别采用聚合氯化铝和聚合硫酸铝铁对化纤综合废水进行了絮凝反应对比实验,并对优选的聚合氯化铝的应用条件进行了研究。其最佳絮凝反应条件为:控制酸析反应的pH在2.20左右,絮凝反应前调节原水pH至5,絮凝剂最佳投加量为3‰,助凝剂选用阳离子型PAM,最佳投加量为3 ppm。絮凝反应使废水色度和COD分别下降67%和38%。