聚甲基[3-(2-羟基-5-氟)苯基]丙基硅氧烷的合成及其应用

以对氟苯酚和3-溴丙烯为原料,无水乙醇为溶剂,经O-烷化、克莱森重排和硅氢加成得到了有机磷毒剂敏感材料聚甲基[3-(2-羟基-5-氟)苯基]丙基硅氧烷.研究了各因素对各步反应的影响,得到的较佳工艺条件为将对氟苯酚和溴丙烯于55℃回流4 h得到中间产物对氟烯丙基苯基醚(Ⅰ),接着将Ⅰ在200℃ 保温7 h得到2-烯丙基_4-氟苯酚(Ⅱ),然后将Ⅱ和含氢硅油在100℃反应4 h.利用FT-IR和1HNMR对各级反应产物结构进行了表征.将聚甲基[3-(2-羟基-5-氟)苯基]丙基硅氧烷料涂覆在QCM传感器上研究了其对有机磷毒剂模拟剂DMMP的响应特性.结果表明传感器响应迅速,对干扰气体、水和乙醇的响应低于含有苯酚官能团的聚合材料.     

Thermodynamics of the Ca(NO3)2 – NaNO3 system

Thermodynamic properties of the quasi binary Ca(NO₃)₂–NaNO₃ system are of interest with respect to thermal energy storage. In the present work the phase diagram as well as thermodynamic properties of the near eutectic mixture 45 mol% Ca(NO₃)₂ – 55 mol% (NaNO₃)₂ were determined experimentally and applied in the assessment of a new Gibbs energy dataset for thermochemical calculations. The enthalpy of fusion of the 45 mol% Ca(NO₃)₂ – 55 mol% (NaNO₃)₂ mixture is determined to be 24.7 ± 0.5 kJ/mol. The melting and crystallization enthalpy have good reproducibility, which makes it possible to use this mixture as a phase change material at temperature 225 °C. The assessed dataset describes liquid phase properties using a subregular solution model in the Redlich-Kister formalism with high accuracy. Therefore it can be used for the prediction of thermodynamic properties of different compositions in the whole Ca(NO₃)₂–NaNO₃ system and be included in databases for calculation of multicomponent systems including other components.     

C3N3(NH2)3、[C(O)NH]3和水双分子间的氢键相互作用

采用密度泛函理论,在B3LYP/6-311+G**水平上对C3N3(NH2)3、[C(O)NH]3、H2O 3种单体在气相中形成的双分了氢键作用体系进行构型优化和频率计算.通过几何优化得到一系列含多个氢键的复合物.频率分析表明,与单体相比,体系形成氢键作用后,参与氢键形成相关的键的红外谱带位置和振动强度都发生明显的变化,其中C3N3(NH2)3-[C(O)NH]3体系中N8-H9键的红移最明显.同时,通过B3LYP/6-311+G**和MP2/6-311+G**水平计算的含基组重叠误差(BSSE)校正的氢键相互作用能分析表明,C3N3(NH2)3-[C(O)NH]3氢键体系的相互作用能最大,其次是([C(O)NH]3)2体系,采用MP2/6-311+G**方法计算的相互作用能分别达到-14.171 kcal·mol-1和-10.217 kcal·mol-1.另外,通过自然键轨道理论揭示氢键相互作用的本质.     

镍(Ⅱ)配合物[Ni(Hpydc)_2]·3(H_2O)的合成结构和量子化学研究

氯化镍与吡啶-2,6-二甲酸(H_2pydc)反应,合成六配位镍配合物[Ni(Hpydc)_2]·3(H_2O),经元素分析、IR和X-射线衍射表征分子结构,该化合物晶体学参数:单斜晶系,空间群P2(1)/n,晶体学数据:a=1.36774(14)nm,b=1.00348(10)nm,c=1.375 87(14)nm,β=115.135 0(10)°,V=1.7096(3)nm~3,Z=4,Dc=1.729 g/cm~3,μ,(MoKα)=1.202 cm~(-1),F(000)=912,R_1=0.0362,wR_2=0.093 3[对I>2σ(I)的衍射]和R_1=0.0510,wR_2=0.1004(对所有的衍射)。共收集9064个数据,其中独立衍射点3018个,可观察衍射[I>2σ(I)]点2293个用于结构精修。配合物的Ni(Ⅱ)原子关于配基原子形成变形八面体。利用量子化学G98W软件,在Lan12dz基组对配合物的稳定性、前沿分子轨道组成及能量进行研究。     

不同浓度钙营养液对烟草矿质营养吸收与积累的影响

本文采用温室水培的方法,研究了不同的钙素供应水平对烟草各种矿质养分的吸收与积累的影响。结果表明,在其它养分形态与浓度一致条件下,随着钙浓度从75mgL-1提高到900mgL-1,烟草生长量呈抛物线型变化。钙浓度为150mgL-1时烟株干物质量最大。超过150mgL-1,随钙的增加而下降,当钙素达900mgL-1(K/Ca为1/6)时,烟株生长严重受抑。随着供钙水平由低到高,烟株氮、磷、钾、锌、锰含量均呈抛物线型变化,含钙量呈直线上升关系,而镁和铜含量则随钙浓度提高而显著下降。烟株各养分积累量均随营养液钙浓度提高呈抛物线型变化,但不同养分出现最大积累量时的营养液钙浓度却不相同。不同供钙水平上烟叶中各元素含量的变化特征与全株的结果基本一致。在低钙浓度范围(75~300mgL-1),钙对钾有协合关系,增钙促进提钾,大于300mgL-1后有拮抗作用,提钙导致降钾。钙与镁、锌、铜、锰间也存在明显的交互作用。烟叶中各元素含量与积累量的变化趋势与整株基本一致。     

铜配合物[Cu(AFO)2]2(SO4)的合成、结构和量子化学研究

硫酸铜与4,5-二氮芴-9-酮(AFO)反应合成四配位铜配合物[Cu(AFO)2]2(SO4),并经元素分析、IR和X-射线衍射表征分子结构,该化合物晶体学参数:单斜晶系,空间群P2(1)/c,晶体学数据:a=0.78885(14)nm,b=1.3358(2)nm,c=1.9292(3)nm,β=96.179(3)°,V=1.7096(3)nm3,Z=4,Dc=1.722 g/cm3,μ(MoKa)=1.236 cm-1,F(000)=1060,R1=0.0437,wR2=0.1225[对I＞2o(1)的衍射]和R1=0.0634,wR2=0.1362(对所有的衍射).共收集10795个数据,其中独立衍射点3576个,可观察衍射[1＞2o(1)]点2553个用于结构精修.配合物的铜原子关于配基原子形成变形平面四方型.利用量子化学G98W软件,在Lan12dz基组对配合物的稳定性、前沿分子轨道组成及能量进行了研究.     

铜(Ⅱ)配合物[Cu(pydc)(H2O)2]2合成、结构和量子化学的研究

合成标题配合物[Cu(pydc)(H2O)2]2(pyde=吡啶-2,6-二甲根),经元素分析、IR和X-射线衍射表征,该配合物晶体属三斜晶系,空间群P1,晶胞参数:a=0.47166(11)nm,b=0.8973(2)nm,c=1.0337(2)am,α=81.120(3)°,β=85.755(3)°,γ=83.352(3)°,V=0.42865(17)nm3,Z=1,Dc=2.051 g/cm3,μ(MoKα)=25.57 mm-1,F(000)=266,and R1=0.0250,wR2=0.0631[对I>2σ(I)的衍射]和R1=0.0313,wR2=0.0651(对所有的衍射).共收集数据2350个,其中独立衍射点1498个,可观察衍射[I>2σ(I)]点1311个用于结构精修.中心Cu原子与配基原子形成变形四棱锥,分子间通过氢键作用形成三维网络结构.利用量子化学G98W程序,在Lanl2dz基组研究配合物的稳定性、前沿分子轨道组成及能量.     

种植密度和施肥对马铃薯养分吸收及土壤肥力的影响

在普施２２５ｔ·ｈｍ－２农家肥和固定Ｎ：Ｐ２Ｏ５：Ｋ２Ｏ比例２：１：３的条件下，研究了不同种植密度和施肥量对马铃薯品种“川芋早”矿质养分吸收利用和土壤肥力的影响。结果表明：加大种植密度和提高施肥水平均使植株群体的每生产千公斤薯块的Ｎ，Ｐ２Ｏ５，Ｋ２Ｏ的吸收量增加，提高肥料的利用率，尤其是高密高肥和高密中肥处理显著。农家肥的施用可以增加土壤中有机质和速效养分的含量，特别是与无机化肥配合施用效果更好     

硼钙营养对不同品种柑桔糖代谢的影响

连续 2年对胡柚和柑桔进行叶面喷施硼 (B)、钙 (Ca)及硼加钙 (B Ca)溶液试验 ,以探讨B、Ca及其互作对柑桔果实糖酸代谢的影响。结果表明 ,硼 (B)、硼加钙 (B Ca)处理能提高柑桔果实成熟前的还原糖、滴定酸含量 ,降低果实收获期的还原糖和滴定酸含量 ,并提高了果实成熟期总糖含量 ;增强柑桔果实发育初期酸性转化酶活性和果实发育后期中性转化酶活性 ;钙 (Ca)处理对柑桔糖代谢的影响效果不明显     

不同作物管理技术对水稻氮素吸收和利用的影响

通过2年田间试验,以杂交粳稻甬优1号为材料,研究不同作物管理技术对稻株氮素吸收利用和产量形成的影响。结果表明,水稻超高产集成技术产量提高21.2%,在分蘖期和抽穗期总氮量低于高产管理,但在成熟期总氮量与高产管理相近;在成熟期叶片、茎鞘中氮滞留量及其占总吸氮量的比例减少;穗部吸氮量提高,其占总吸氮量的比例增加。因此,水稻超高产集成技术能促进水稻叶片和茎鞘中的贮藏性氮向穗部转运,在总氮吸收量变化不大情况下,氮素的吸收利用率、氮素的农学利用率、氮素的生理利用率和氮肥偏生产力等均显著提高。     

镉胁迫下磷供应对芥菜生长和镉吸收的影响

采用土培和水培试验,研究了镉胁迫下磷供应对芥菜生长和镉吸收的影响。土培试验表明:施磷可以提高镉胁迫下小叶芥菜和雪里蕻种子的发芽率,提高小叶芥菜的生物量,而对雪里蕻生物量影响不大;施磷可以减少土壤中有效态镉含量,明显降低植株体内镉含量;植株体内的全磷含量随外加磷浓度的提高而显著增加。水培结果表明:镉胁迫下,磷供应对雪里蕻植株生物量影响不大;随着磷供应水平的增加,植株体内的全磷含量明显增加,但植株地上部镉、锌、钙、镁、锰等元素的含量明显降低。     

N2O与HX(X=F,Cl,Br)分子间作用的电子密度拓扑研究

运用量子化学微扰理论MP2方法和密度泛函B3LYP方法,采用6-311++G(d,p)基组,对N_2O分子与HX(X=F,Cl,Br)分子形成的氢键复合物进行构型优化和能量计算。利用电子密度拓扑分析方法对氢键复合物的拓扑性质进行了分析,探讨了分子间氢键作用的本质。研究结果表明,N_2O分子与HX(X=F,Cl,Br)分子间可形成O…H-X和N…H-X 2类氢键;形成氢键后,作为电子受体的HX(X=F,Cl,Br)分子中的H-X键键长增加振动频率减小;氢键作用能按照NNO…HF、NNO…HCl、NNO…HBr和ONN…HF、ONN…HCl、ONN…HBr的顺序递减;氢键形成过程中存在从电子给体到电子受体的电荷转移。复合物体系中的氢键作用介于共价键和离子键之间,并且以静电作用为主。     

CO_2和CH_4分子在Ni(111)表面吸附的分子模拟研究

采用蒙特卡洛方法模拟退火计算了CH_4和CO_2在Ni催化剂表面竞争吸附的等量吸附热和等温吸附线,结果表明,较优的操作参数为:温度范围:1000 K~1150 K,压力:101.33 kPa,CO_2/CH_4:大于1.00。随后通过分子动力学模拟计算了CH_4和CO_2解离过程中产生的自由基在Ni(111)表面的吸附行为,其中CH_3、CH和C倾向于吸附在fcc位点,而H更易于在hcp位发生吸附,CH_2在桥位的吸附最优。同时吸附能的绝对值的顺序是:CH_2CH_4CH_3CHCH,吸附能的绝对值越大,相应的吸附构象越稳定。而CO_2和CO倾向于吸附在桥位,O更易于在顶位发生吸附,OH在hop位点的吸附最优。     

A review of the meta-analysis by Tingir and colleagues (2017) on the effects of mobile devices on learning

Tingir et al. (2017) concluded from their meta-analysis that the subject areas taught through mobile devices had significantly higher achievement scores (d = 0.48) than the ones taught with traditional teaching methods. Given the relatively high positive effect of mobile devices on student achievement, we carefully analysed the selected research in this meta-analysis. We reviewed Tingir et al.’s (2017) meta-analysis based on analysis of the methodology of the selected research, while drawing on the work of Slavin (2003), Cheung and Slavin (2016), and Sung et al. (2019). Twelve of the 14 (86%) studies included in the meta-analysis done by Tingir and his team (2017) present such major methodological flaws that they should not have been included. Our analysis leads us to believe that the conclusion of Tingir et al. (2017) is not justified. It is recognized that duration of experiment is negatively correlated with effect size: the shorter the duration, the higher the effect (Burston, 2015; Slavin & Lake, 2009). Although demanding more effort, the field of education must raise the bar if it is to have knowledge of acceptable value.     

Proposing a new integrated model based on sustainability balanced scorecard (SBSC) and MCDM approaches by using linguistic variables for the performance evaluation of oil producing companies

Using the balanced scorecard approach based on sustainable development parameters is a powerful and useful methodology to evaluate the sustainable performance of organization or company. In this paper, a new approach based on sustainability balanced scorecard (SBSC) and multi criteria decision making (MCDM) approaches is developed for evaluating the performance of oil producing companies in Iran. For reflecting the interdependent relationships among factors influencing the problem under consideration, analytical network process (ANP), a branch of the MCDM techniques, is employed. However, using the ANP method for calculating the preference ratings of alternatives is a time-consuming and bothersome process; therefore, COPRAS (COmplex PRoportional ASsessment) technique is adopted to prioritize the feasible alternatives in terms of linguistic variables. Based on this study, the results demonstrate the effectiveness of the proposed model. The performance evaluation model proposed by using a combination of the MCDM methods and the SBSC approach helps authorities to make an attempt for achieving a competitive advantage.     

Comment on “Option pricing under the Merton model of the short rate” by Kung and Lee [Math. Comput. Simul. 80 (2009) 378-386]

In this note, we correct the formula given in Ref. [3] for European call and put option under Merton's model of the short rate. We give a probabilistic derivation making use of the “change of numeraire” technique which is simpler and more standard.