Biomorphic Silicon Nitride Ceramics with Fibrous Morphology Prepared by Sol Infiltration and Reduction–Nitridation

Biomorphic silicon nitride (Si₃N₄) ceramics with fibrous morphology were fabricated by combining sol–gel infiltration with carbothermal reduction nitridation from wood precursor. Y₂O₃-incorporated silica sol was used as the infiltrated solution to promote the formation of fibrous Si₃N₄ grain at 1600°C under high nitrogen pressure (0.6 MPa). The influence of sintering conditions (additive and temperature) on the phase composition and microstructure of sintering bodies was analyzed, and the reaction mechanism is discussed.     

In vivo and in vitro lipid accumulation inBorago officinalis L.

Seeds of 13 accessions of borage (Borago officinalis) varied in total fatty acid content from 28.6 to 35.1% seed weight, with linoleic, γ-linolenic, oleic and palmitic as the predominant fatty acids, averaging 38.1%, 22.8%, 16.3% and 11.3% of total fatty acids, respectively. There was an inverse relation between γ-linolenic acid (25.0 to 17.6%) and oleic acid (14.5 to 21.3%). Fatty acid content of leaf tissues was 9.1% dry weight, with α-linolenic acid 55.2% and γ-linolenic acid 4.4% of total fatty acids. Cotyledons were the major source of fatty acids in seeds. Seed fatty acid content increased from <1 mg at six days postanthesis to about seven mg at maturity (22 to 24 days). Individual fatty acid content of seed was relatively constant after day 8. When immature embryos from 6 to 16 days postanthesis were cultured in a liquid or semisolid basal medium, fatty acid composition was similar to that of in vivo-grown seeds. Growth of cultured embryos decreased as sucrose concentration was increased from 3 to 20% in the basal medium, and most embryos did not survive 30% sucrose; fatty acid as a percentage of dry weight was maximal at 6% sucrose.     

节水型洗衣粉的研制

本文论述研制节水型洗衣粉的必要性及其制造过程。并对洗衣粉的表面活性剂、助剂、消泡剂进行配方优选，研制出去污力强的节水型洗衣粉。     

A new parallel lattice reduction algorithm for BKZ reduced bases

In order to implement the original BKZ algorithm in parallel,we describe it in terms of parallelism and give its parallel implementation scheme.Then we analyze the efficiency of algorithm’s parallel implementation and show that the speedup factor of BKZ algorithm in parallel is extremely low.Therefore we present a new parallel lattice reduction algorithm suitable for multiprocessor computer architecture.The new algorithm can obtain a BKZ reduced basis and the parallel speedup is effective.Also with the practical results,although the computational complexity increases compared with the original BKZ algorithm,we still indicate that the new algorithm performs well in parallel and the time cost in parallel is less.At the same time,we show that the length of the shortest vector is smaller.     

大型泵站自动化控制系统组成及管理

介绍大型泵站自动化系统的结构及组成,分析其微机自动化管理过程中出现的问题．并提出处理措施及注意事项。     

在硫酸化氧化物催化剂上二氯甲烷的低温催化降解

采用色谱微反联用技术研究了在硫酸化氧化物催化剂上二氯甲烷的低温催化降解。实验发现，硫酸化氧化物催化剂如ＴｉＯ２－（ＳＯ４）在较低反应温度（如２７５℃）时表现出较高的反应活性，转化率１００％，并且其催化活性次序为：ＴｉＯ２－（ＳＯ４）＞ＺｒＯ２－（ＳＯ４）＞ＣｅＯ２－（ＳＯ４）。实验结果还表明：催化剂的酸性关联降解二氯甲烷的催化活性。同时，水汽的存在明显降低了其催化活性。     

邻苯基苯酚的合成研究

以环己酮为原料，经过缩合得到环己酮二聚体，通过浸渍法制备γ—Al2O3负载Pt—K2SO4作为环己酮二聚体脱氢制备邻苯基苯酚的催化剂，通过讨论脱氢过程的各种影响因素以确定脱氢催化剂的组成和最佳反应条件，从而得到较高选择性和寿命的催化剂，进一步得到收率高，纯度好的产品。     

Thermogravimetric analysis of methyl methacrylate‐graft‐natural rubber

The thermal degradations of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates (B) in nitrogen were studied by thermogravimetric analysis. The results indicate that the thermal degradation of MG in nitrogen is a one‐step reaction. The degradation temperatures increase along with the increment of heating rates. The temperature of initial degradation (T₀) is 0.448B + 362.4°C, the temperature at maximum degradation rate, that is, the peak temperature on a differential thermogravimetric curve (T_p) is 0.545B + 380.7°C, and the temperature of final degradation (T_f) is 0.476B + 409.4°C. The degradation rate at T_p is not affected by B, and its average value is 48.9%; the degradation rate at T_f is not affected by B either, and its average value is 99.3%. The reaction order (n) is 2.1 and is not affected by B. The reaction activation energy (E) and the frequency factor (A) increase along with B, and the apparent reaction activation energy (E₀) is 254.6 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2952–2955, 2002     

Synthesis of novel functional polyolefin containing carboxylic acid via Friedel-Crafts acylation reaction

The strong polar group, carboxylic acid, has triumphantly been introduced into ethylene and allylbenzene copolymers without obvious degradation or crosslinking via Friedel-Crafts (F-C) acylation reaction with glutaric anhydride (GA), succinic anhydride (SA) and phthalic anhydride (PA) in the presence of anhydrous aluminum chloride in carbon disulfide. Some important reaction parameters were examined in order to optimize the acylation process. In the optimum reaction conditions, almost all of the phenyls can be acylated with any anhydride. The microstructure of acylated copolymer was characterized by FT-IR, ¹H NMR and ¹H-¹H COSY. All the peaks of acylated copolymers can be accurately attributed, which indicates that all the acylation reactions occur only at the para-positions of the substituent of the aromatic rings. The thermal behavior was studied by differential scanning calorimetry (DSC), showing that the melting temperatures (T_ms) of acylated copolymers with GA firstly decrease slowly and then increase significantly with the increase of the amount of carboxyl acid groups.     

超临界气体在聚合物加工中的应用

介绍了超临界气体的性质，以及近年来超临界CO2在聚合物加工中的应用，并对此技术住聚合物加工中存在的问题和未来的发展前景进行了总结和展望。