反式 -1,4-聚异戊二烯相对分子质量的调节

采用负载钛本体沉淀聚合法,以氢气作链转移剂,制备了不同相对分子质量的反式-1,4-聚异戊二烯(TPI),讨论了老化、氢气调节及塑炼对其相对分子质量的影响,以及不同相对分子质量TPI的结构与性能。结果表明,本体系合成TPI的数均相对分子质量为(5～15)×104,相对分子质量分布为2.00～3.00;门尼粘度为20～120时,随着TPI相对分子质量的降低,其结晶速度提高,结晶度无明显变化,拉伸强度明显降低,扯断伸长率、屈服强度和邵尔A型硬度无明显变化。     

悬浮法合成固体粒状丙烯酸树脂

研究了悬浮法合成固体丙烯酸树脂颗粒。讨论了不同软硬单体配比对丙烯酸树脂颗粒的玻璃化转变温度、相对分子质量及其分布的影响以及不同的引发剂及悬浮剂对其聚合过程、最终产物形态及上述性能的影响。制得的丙烯酸树脂的数均相对分子质量用凝胶渗透色谱(GPC)测定为3.9×104～6.2×104,相对分子质量分布为2.04～2.32;用红外光谱图表征了制得的丙烯酸树脂结构。差示扫描量热法(DSC)测定了聚合物的玻璃化转变温度(Tg)。     

Assessment of the relative agronomic effectiveness of phosphate rocks under glasshouse conditions

Six phosphate rocks (PRs) of varying reactivities were compared with monocalcium phosphate (MCP) in a glasshouse experiment growing perennial ryegrass (Lolium perenne cv. Nui) as the test plant on four soils of contrasting P sorption capacity and exchangeable Ca. The cumulative dry matter yield over 10 harvests showed a significant response to P application in all soils. Based on relative yield and P uptake, MCP was the most effective P fertilizer followed by the reactive phosphate rocks, which were superior to the unreactive rocks in all soils. The relative agronomic effectiveness (RAE) and substitution ratio (SR) of individual PR fertilizers, calculated with respect to MCP using the methods of vertical and horizontal comparison, respectively, were similar over a range of fertilizer rate. There was a decline or slight increase in the performance of PRs with time in the low P sorption soils but a consistent increase in the high P sorption soils. Some initial influence of exchangeable Ca content of the soils on the relative performance of PRs was also observed. Generally the PRs performed better in high P sorption soils than low P sorption soils and in low exchangeable Ca soils than high exchangeable Ca soils.     

UHMWPE混炼接枝马来酸酐研究

讨论了超高相对分子质量聚乙烯(UHMWPE)混炼接枝马来酸酐(MAH)过程中，单体MAH用量、引发剂DCP用量、交联抑制剂己内酰胺(CAILA)用量、流动改性剂硬脂酸钙(CaSt2)用量及混炼温度、时间等工艺条件对UHMWPE接枝率和凝胶含量的影响。用红外光谱表征了接枝物的存在。并用滴定分析法和重量分析法测定了接枝物UHMWPE～g～MAH的接枝率和凝胶含量。实验表明，MAH用量为5份、DCP为0．15份、CALA为0．1份、CaSt2为1份时。混炼温度175∽180℃。混炼时间14min时，可得到接枝率0．75％、凝胶含量1．48%的UHMWPE接枝物。     

带未知干扰的模块化航天器系统相对轨道的队形控制

基于多智能体系统一致性理论,在有向拓扑结构中对模块化航天器相对轨道的队形控制问题进行研究.考虑与状态相关的未知外部干扰,在存在模块质量不确定性的情形下,基于自适应增益技术,设计仅依赖模块自身及其邻近模块信息的分布式控制算法,并通过Lyapunov稳定性方法证明闭环系统是渐近稳定的.最后在Matlab/Simulink中对6个模块组成的模块化航天器系统的队形进行仿真分析,仿真结果表明所设计的控制律是有效且可行的.     

Stabilized heteropolyacid/Nafion composite membranes for elevated temperature/low relative humidity PEFC operation

Organic/inorganic composite membranes with different inorganic heteropolyacid (HPA) additives maintain sufficient proton conductivities for atmospheric pressure elevated temperature (>100 °C) polymer electrolyte fuel cell (PEFC) operation. However, membrane and membrane electrode assembly (MEA) processing is severely curtailed because of the solubility of the HPA additives in aqueous media. Composite membranes with the HPA (phosphotungstic acid; PTA) additive rendered insoluble by ion exchanging protons with larger cations such as Cs⁺, NH₄⁺, Rb⁺ and Tl⁺ were fabricated. The additive loss in aqueous media was lowered from nearly 100% (unmodified HPA) to about 5% (modified HPA). The membranes were robust, and demonstrated low H₂ crossover currents of around 2 mA/cm² for a 28 μm thick membrane. All membranes were evaluated at high temperatures and low relative humidities in an operating fuel cell. The conductivities of the composite membranes at 120 °C and 35% relative humidity were on the order of 1.6 × 10⁻² S/cm.     

国产SEBS流变性能评价

通过对国产SEBS(氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物)流变性能进行测试．分析不同结构、不同嵌段的S／B质量比值、不同相对分子质量、不同加工温度对SEBS产品流变性能的影响．促进用户对国产SEBS性能的了解。     

Agronomic evaluation of fertilizer products derived from Sukulu Hills phosphate rock

Partial acidulation of phosphate rock (PR) or compaction of PR with soluble P fertilizers can improve the usefulness of unreactive PR for use as P fertilizer. A greenhouse study was conducted to evaluate nonconventional phosphate fertilizers derived from a low reactive Sukulu Hills PR from Uganda. Raw PR (which contained 341.0 g kg^–1 Fe₂O₃), beneficiated or concentrate PR, partially acidulated PR (PAPR) and PR compacted with triple superphosphate (TSP) were evaluated. Compacted materials had a P ratio of PR:TSP = 50:50. PAPR materials were made by 50% acidulation with H₂SO₄. TSP was used as a reference fertilizer. Fertilizers were applied to an acidic (pH = 5.4) Hiwassee loam (clayey, kaolinitic, thermic Rhodic Kanhapludults) at rates of 0, 50, 100, 200, 300 and 400 mg P kg^–1 soil. Two successive corn (Zea mays L.) crops were grown for 6 weeks. Compacted concentrate PR + TSP and raw PR + TSP were 94.4 and 89.7% as effective as TSP, respectively, in increasing dry-matter yields for the first corn crop. PAPR from the concentrate was 54.8% as effective as TSP. Raw PR, concentrate PR and the PAPR from the raw PR were ineffective in increasing dry-matter yields. The same trends were obtained when P uptake was used to compare effectiveness. Ineffectiveness of the raw PR and its corresponding PAPR was attributed to a high Fe₂O₃ content in the raw PR. Bray I and Pi paper were found to be nearly equally suitable at estimating available P in the soils treated with responsive fertilizer materials. Mehlich 1 overestimated available P in soil treated with raw PR, concentrate PR or the PAPR from the raw PR.     

Agronomical evaluation of phosphate fertilizer as a nutrient source of phosphorus for crops: Isotopic procedure

The agronomic effectiveness of P fertilizers, as sources of phosphorus for crops, was evaluated using the quantities, P_f, of phosphorus taken up byLolium perenne grown on 14 soils during greenhouse experiments in pot cultures. The P_f quantities were determined using³²P-labelled fertilizers. Data were analysed using a new concept: the Isotopic Relative Agronomic Effectiveness (IRAE). The IRAE value was defined as the ratio of the P_f quantity, taken up by a crop, of a tested fertilizer over the P_f quantity, taken up by a crop, of a fertilizer used as standard. In our experiments diammonium phosphate (DAP) was used as standard P fertilizer and two rock phosphates, the North Carolina rock phosphate (NCPR) and a calcium-iron-aluminium phosphate (Phospal), were tested. As a linear relationship between P_f(NCPR) quantities and P_f(DAP) quantities was obtained, with r² = 0.95, when the application rates increased from 15 mgP (kg soil)^–1 to 200 mgP (kg soil)^–1, it is conciuded that IRAE values for a given fertilizer, other than the standard fertilizer, could be determined with a single rate of application. As regards soil pH in the range 4.7 to 8.2 the IRAE_NCPR is related to soil pH by a curvilinear relationship: log IRAE_NCPR = –(0.44) pH + 4.05 with r² = 0.89. The average of IRAE_phospal values was 0.15 with a standard error = 7% irrespective of soil pH. Then a logarithmic relationship was obtained between IRAE values of the two tested fertilizers and their water P-solubility determined at the soil pH where they were applied.     

基于R软件的金融资产收益波动率建模分析

金融资产收益波动率是金融计量分析的核心议题,该文考虑对其建模分析的计算机实现问题。利用R软件的强大计算与绘图功能,给出金融资产收益波动率各个模型的模拟实现以及对实际金融市场数据的各种建模分析。