Structure of KLa(WO4)2 with a novel isolated La polyhedron

The compound KLa(WO₄)₂ crystallizes in the tetragonal with space group 14(l)/a (C_4h ⁶) and cell parameters a=b=5.447 ?, c=12.080 ?, Z=1, V=358.41 ?³, D=3.121 g/cm³, F(000)=288, final R=0.079. R_w=0.082 for 208 observed reflections with I ≥ 3 σ > (I). The structure consists of WO₄ tetrahedron, KO₈ and LaO₈ polyhedrons. LaO₈ polyhedrons are isolated from each other, with La³⁺ ions joined by means of La-O-W-O-La. This structural characteristic will result in a weak interaction between active ions and a lower fluorescence concentration quenching effect. Electronic Publication     

川西坳陷雷口坡组常量元素特征及其意义

通过对川西坳陷丰卤1井雷口坡组岩屑样品的常量元素分析,研究K含量,w(FeO)/w(Fe₂O₃)值特征以及w(MnO)/w(FeO+ Fe₂O₃)值特征,发现雷口坡组K含量变化与深度成正比关系,K含量整体偏小,未能达到钾盐沉积的标志线;w(FeO)/w(Fe₂O₃)值整体小于1,反映出沉积环境为氧化环境,有着干燥、炎热的气候条件;极小的w(MnO)/w(FeO+ Fe₂O₃)值（<1）不仅反映了氧化的沉积环境和干热的气候条件,还反映了较浅的水体环境。干燥炎热的气候条件以及浅水的次级构造条件都指示着川西坳陷雷口坡组具备良好的钾盐沉积条件,最后建立w(FeO)-w(Fe₂O₃)-w(MnO)判别图,判别图包含3个区域,分别为湿冷深水区、干热浅水区以及湿冷浅水区,发现雷口坡组属于干热浅水区。     

Effect of cation exchange on the distribution and movement of cations in soils with variable charge. I. Effect of lime on potassium and magnesium exchange equilibria

The influence of Ca(OH)₂ on K and Mg exchange equilibria in three New Zealand soils was studied. Calcium hydroxide was mixed with each soil to raise the pH to about 6 or 7. For each Ca(OH)₂ treatment, K and Mg exchange isotherms were determined, from which the equilibrium activity ratios were derived. Exchange coefficients and solution activity ratios were calculated according to the Gapon convention.The addition of Ca(OH)₂ produced varying effects in the Gapon exchange coefficient for both K and Mg. The magnitude and direction of change in the exchange coefficient were related to the cation initially dominating the exchange sites, rate of Ca(OH)₂ addition, soil colloids contributing to the CEC and specific interactions of Ca with these soil colloids.Addition of Ca(OH)₂ reduced the equilibrium activity ratio of all soils. Changes in the bonding strength of K and Mg with increasing CEC were suggested as a possible mechanism for this decrease.     

低钾胁迫对大豆叶片膜脂过氧化及保护酶活性的影响

以在大田筛选的钾高效型大豆品种沈农6号和钾低效型品系铁95068-5为试材,研究了不同供钾水平对大豆膜脂过氧化作用及保护酶活性的影响。试验结果表明,随着钾浓度的降低,2个品种在各生育时期的相对电导率和MDA含量均有所增加,但沈农6号增加幅度不大,而铁95068-5则增幅较大。在每个生育时期,2个品种各保护酶活性均随着钾浓度的降低而增强,说明适度低钾胁迫会激发大豆的保护酶活性;不同钾浓度下,沈农6号和铁95068-5叶片SOD活性均随着大豆的生长发育逐渐下降;CAT和POD活性先逐渐增强,随后下降：2个品种CAT活性到开花盛期（R2）达到峰值,POD活性分别在鼓粒期（R6）和盛荚期（R4）达到峰值。沈农6号各生育时期SOD、CAT和POD活性均高于同期的铁95068-5,表明大豆钾效率的高低与其体内保护酶系统对活性氧的清除能力直接相关。     

Effects of food preservatives on Alternaria alternata growth and tenuazonic acid production

The effects of different organic acids on Alternaria alternata growth and tenuazonic acid production (TeA) were evaluated. Both TeA pure toxin solution and TeA production in solid medium were considered. Sodium benzoate, potassium sorbate and sodium propionate, all preservatives commonly used by food industry in Argentina, were tested. TeA was stable as pure toxin solution when was treated with the salts of organic acids used. A differential effect was observed when the preservatives were evaluated in relation to A. alternata growth and TeA production in solid medium. L evels above 10mg/kg of sodium benzoate and potassium sorbate produced a total inhibition of fungal development and toxin biosynthesis. Sodium propionate produced a 59% decrease in A. alternata growth and total inhibition of TeA production only at the highest concentration of preservatives used.     

Hot air expansion of potato starch pellets with different water contents and salt concentrations

The expansion and puffing kinetics of commercial potato starch pellets were examined using a hot air fan oven in order to determine the puffing kinetics. The time for the onset of expansion showed uni-molecular type kinetic behaviour and was modelled by an Arrhenius plot. A pseudo-activation enthalpy for pellet expansion was also determined. The initial moisture content of the commercial pellets was controlled and the changes in the extent of puffing and the pseudo-activation enthalpy were found. The effect of type and quantity of cation in the formulation was then investigated. Expansion occurred even when no cation was added although the presence of cation did improve pellet expansion. The ratio of the native and pre-gelatinized starch in the pellets was also varied and showed to have limited effect on the extent of expansion. The puffing mechanism is discussed in light of these observations.     

硫酸钾钻井液体系的室内评价与应用

受加拿大皇朝公司在宋芳屯油田州13区块采用硫酸钾钻井液成功进行油层保护的启发,在室内优选出的硫酸钾钻井液体系的基本配方为:5%膨润土 0.4%Na2CO3 5.0%K2SO4 1000mg/LDCL 200mg/LDesco 100mg/LAlcome 500mg/LSAP 1000mg/LLT 1000mg/LKEL,K 含量为50000mg/L时,钻井液具有合适的粘度、切力和滤失量,页岩滚动回收率大于85%,岩心静态膨胀率小于2%,岩心伤害率小于20%。其保护油气层的机理为:K 抑制粘土水化膨胀的能力、油层保护剂的吸附能力、K 与油层保护剂的协同作用。     

界面反应对K_2O·STiO_2(W)/ZL109复合材料高温强度的影响

K_2O·8TiO_2(W)/ZL109复合材料在500℃下热暴露20h后高温强度最高,热暴露时间超过20h,随着热暴露时间的延长,其高温强度逐渐下降。界面反应是导致其高温强度下降的原因。     

干湿交替过程对黄土高原几种主要土壤钾有效性的影响

室内模拟试验研究不同温度条件下干湿交替对黄土高原区四种土壤有效钾的影响,结果表明:(1)土壤钾有效性受干湿交替过程影响较大,干湿交替次数与有效钾含量间具有y=a blogx函数关系;(2)温度升高,增强了干湿交替的剧烈程度,提高土壤钾的固定量,显著降低了土壤钾的有效性;(3)建立了反映干湿交替次数、土壤物理性粘粒和粘粒含量比值、以及钾固定量三者之间的关系方程。     

油类对COD测定结果影响的探讨

本文通过对重油、15号机油、正已烷3种有机物质的加入实验,查明了以上物质在标准重铬酸钾法中的氧化情况,并得出在钢铁企业含油废水中,用重铬酸钾法所测得的COD值不能全部包括废水中油类(机油、重油)的有机物质的结论。