Improved Melting Strength of Polypropylene by Reactive Compounding With Ultrafine Full-Vulcanized Polybutadiene Rubber (UFBR) Particles

Ultrafine full-vulcanized polybutadiene rubber (UFBR) in particle sizes of ca. 50-100 nm has been used for modifying mechanical and processing performances of polypropylene (PP), and PP-g-maleic anhydride (PP-MA) has been used as a compatibilizer for enhancing the interfacial adhesion between the two components. The results show that PP/UFBR possesses rheological behaviors such as highly branched PP when UFBR content in blends reaches 10 wt%, while in contrast, the much low content of UFBR combining small amount of PP-MA endows the material with rheological characteristics of high melt strength materials like highly branched PP.

Spontaneous formation of two-dimensional gold networks at the air-water interface and their application in surface-enhanced Raman scattering (SERS)

Two-dimensional (2-D) gold networks were spontaneously formed at the air-water interface after HAuCl4 reacted with fructose at 90 degrees C in a sealed vessel, in a reaction in which fructose acted as both a reducing and a protecting agent. Through fine-tuning of the molar ratio of HAuCl4 to fructose, the thus-formed 2-D gold networks can be changed from a coalesced pattern to an interconnected pattern. In the coalesced pattern, some well-defined single-crystalline gold plates at the micrometer-scale could be seen, while in the interconnected pattern, many sub-micrometer particles and some irregular gold plates instead of well-defined gold plates appeared. It is also found that the 2-D gold networks in the form of an interconnected pattern can be used as substrates for surface-enhanced Raman scattering (SERS) because of the strong localized electromagnetic field produced by the gaps between the neighboring particles in the 2-D gold networks.

Syntheses and properties of polyimides derived from diamines containing 2,5-disubstituted pyridine group

A Series of novel homo- and copolyimides containing pyridine units were prepared from the heteroaromatic diamines, 2,5-bis (4-aminophenyl) pyridine and 2-(4aminophenyl)-5-aminopyridine, with pyromelltic dianhydride (PMDA), and 3,3',4,4'-biphenyl tertracarboxylic dianhydride (BPDA) via a conventional two-step thermal imidizaton method. The poly(amic acid) precursors have inherent viscosities of 1.60-9.64 dL/g (c = 0.5 g/dL in DMAC, 30 degrees C) and all of them can be cast and thermally converted into flexible and tough polyimide films. All of the polyimides show excellent thermal stability and mechanical properties. The polyimides have 10% weight loss temperature in the range of 548-598 degrees C in air. The glass transition temperatures of the PMDA-based samples are in the range of 395-438 degrees C, while the BPDA-based polyimides show two glass transition temperatures (T(g)1 and T(g)2), ranging from 268 to 353 degrees C and from 395 to 418 degrees C, respectively. The flexible films possess tensile modulus in the range of 3.42-6.39 GPa, strength in the range of 112-363 MPa and an elongation at break in the range of 1.2-69%. The strong reflection peaks in the wide-angle X-ray diffraction patterns indicate that the polyimides have a high packing density and crystallinity.

两亲性线性-超支化多臂共聚物在水溶液中自组装为阳离子囊泡的研究

利用两亲性线性-超支化多臂共聚物聚乙二醇-聚乙烯亚胺-聚谷氨酸苄酯(PEG-PEI-PBLG)在水溶液中自组装为阳离子囊泡.利用透射电镜、动态光散射、静态光散射和zeta电位仪对囊泡结构进行了表征.PEG-PEI-PBLG囊泡具有双分子层结构,壁厚5~10nm,直径在100nm左右.由于PEI在水溶液中的质子化作用,囊泡表面携带有正电荷,其表面电势为+25.2mV,因此PEG-PEI-PBLG阳离子囊泡具有担载负电性蛋白的能力.

Luminescence of RE2+ (RE = Sm, Yb) in barium octoborate

The reduction process from trivalent to divalent state for Sm3+ and Yb3+ ions in barium berates (BaB8O13) prepared in air was observed. The luminescence properties of these divalent rare-earth ions were studied. Yb2+ shows an f-d broad emission band, due to the 4f(14) --> 4f(13)5d transition, while the Sm2+ ion shows an f --> f transition. From the spectra of Yb2+, and using the D-5(0) --> F-7(0) transition of Sm2+ as a structural probe, two crystallographic sites were found to be available for the cations in the host. Vibronic transitions of Sm2+ were observed at low temperature. BaB8O13 was found to be a good host for reducing the trivalent rare-earth ions to divalent state and to exhibit interesting spectroscopic properties,

The involvement of HSP22 from bay scallop Argopecten irradians in response to heavy metal stress

Heat shock protein 22 (HSP22) is an important member of small heat shock protein (sHSP) subfamily which plays a key role in the process of protecting cells, facilitating the folding of nascent peptides, and responding to stress. In the present study, the cDNA of HSP22 was cloned from Argopecten irradians (designated as AiHSP22) by rapid amplification cDNA end (RACE) based on the expressed sequence tags (ESTs). The full-length cDNA of AiHSP22 was of 1,112 bp, with an open reading frame of 588 bp encoding a polypeptide of 195 amino acids. The deduced amino acid sequence of AiHSP22 showed high similarity to previously identified HSP22s. The expression patterns of AiHSP22 mRNA in different tissues and in haemocytes of scallops exposed to Cd2+, Pb2+ or Cu2+ were investigated by real-time quantitative RT-PCR. The mRNA of AiHSP22 was constitutively expressed in all examined tissues, including haemocyte, muscle, kidney, gonad, gill and heart. The expression level in heart and muscle was higher than that in other tissues. The mRNA level of AiHSP22 in haemocytes was up-regulated after a 10 days exposure of scallops to Cu2+, Pb2+ and Cd2+. However, the expression of AiHSP22 did not increase linearly along with the rise of heavy metal concentration. Different concentrations of the same metal resulted in different effects on AiHSP22 expression. The sensitive response of AiHSP22 to Cu2+, Pb2+ and Cd2+ stress indicated that it could be developed as an indicator of exposure to heavy metals for the pollution monitoring programs in aquatic environment.

A simple and low-cost airlift photobioreactor for microalgal mass culture

A simple, low-cost, and efficient airlift photobioreactor for microalgal mass culture was designed and developed. The reactor was made of Plexiglas, and composed of three major parts: outer tube, draft tube and air duct. The fluid-dynamic characteristics of the airlift reactor were studied. The system proved to be well suited to the mass cultivation of a marine microalga, Chlorella sp. In batch culture, the biomass volumetric output rate of 0.21 g l(-1) d(-1) was obtained at the superficial gas velocity of 4 mm s(-1) in the draft tube.

牦牛暖季放牧对牧草消化率的影响

通过垂穗披碱草-星星草混播草地连续3个放牧季的牦牛放牧试验,对不同放牧强度下牧草的消化率进行了研究.结果表明:放牧强度对牦牛所食牧草中酸性洗涤纤维消化率的影响极显著(P＜0.01),对粗纤维消化率的影响显著(P＜0.05),而对所食牧草中的总能、粗蛋白、粗灰分和中性洗涤纤维的影响不显著(P＞0.05);放牧时间对中性和酸性洗涤纤维的影响极显著(P＜0.01),而对牧草总能、粗蛋白、粗纤维和粗灰分的影响不显著(P＞0.05).尽管牦牛的采食量均随放牧强度的增加而减小,但牦牛对采食牧草各营养成分的消化率并未出现规律性变化.

南海北部大陆边缘盆地热演化史及其与油气关系

This thesis focuses on the present-day thermal field features, evolution and their connections to hydrocarbon generation of the three continental margin basins-the Yinggehai (Yingge Sea), Qiongdongnan(southeast Qiong), and Pear River Mouth basins-in northern South China Sea, based on available data from drillings, loggings, seismic cross-sections, BHTs, thermal indicators (Ro%, inclusion, etc) and geopressure measurements. After studying of present-day distribution of geothermal field and thermal disturbance of fluid in the sedimentary strata, the author discovered that the distribution of gas fields in Yinggehai Basin are closely related to the distribution of anomalously high thermal gradient area, whereas it is not the case for the Pear River Mouse Basin. And detailed processing of the fluid inclusion data indicates that geothermal fluids activated frequently in this area, and they may mainly be derived upward from the overpressure and hydrocarbon-generating beds, 3000-4500 m in depth. Therefore, the abnormal gradients in sedimentary beds were mainly caused by the active geothermal fluids related to hydrocarbon migrating and accumulating in this area. Because of the effect of overpressure retarding on vitrinite reflectance, the thermal indicators for thermal history reconstruction should be assessed before put into use. Although some factors, such as different types of kerogen, heating ratio, activities of thermal fluids and overpressure, may have effects on the vitrinite reflectance, under the circumstance that thermal fluids and overpressure co-exist, overpressure retarding is dominant. And the depth and correction method of overpressure retarding were also determined in this paper. On the basis of reviewing the methods of thermal history studies as well as existing problems, the author believes that the combination of thermal-indicator-inversion and tectono-thermal modeling is an effective method of the thermal history reconstruction for sedimentary basins. Also, a software BaTherMod for modeling thermal history of basins was successfully developed in this work. The Yinggehai Basin has been active since Tertiary, and this was obviously due to its tectonic position-the plate transition zone. Under the background of high thermal flow, long-term quick subsidence and fluid activities were the main reasons that lead to high temperature and overpressure in this basin. The Zhujiangkou Basin, a Tertiary fault-basin within the circum-Pacific tectonic realm, was tectonically controlled by the motion of the Pacific Plate and resembles the other petroliferous basins in eastern China. This basin developed early, and characterized intensive extension in the early stage and weak activity in the later stage of its development. Whereas the Qiongdongnan Basin was in a weak extension early and intensity of extension increased gradually. The relative geographical locations and the extensional histories of three basins ilustrate that the northern continental margin of South China Sea spread from south to north. On the other hand, the Qiongdongnan and Yinggehai Basins may have been controlled by the same tectonic regime since later Tertiary, whereas the Zhujiangkou Basin was not meaningfully influenced. So, the tectono-thermal evolution character of the Qiongdonnan basin should be closely to the other two. It may be concluded that the three basins have been developed within the active continental margin since Tertiary, and the local lithosphere might undergo intensive extension-perhaps two or three times of episodic extension occurred. Extension lead to large tectonoc subsidence and extreme thick Tertiary sediments for hydrocarbon generation in the basins. In response to the periodic extension of the basins, the palaeothermal flow were also periodical. The three basins all have the characteristics of multi-phase thermal evolutions that is good for oil-gas generation. And the overpressure expands the depth range of oil-gas habitat, which is meaningful to petroleum exploration in this region.

封闭垃圾填埋场通过地表向大气释放汞的测定

利用动力学通量箱及自动测汞仪联用技术，于2004年3月中旬对贵阳市的一座封闭生活垃圾填埋场汞通过地表向大气释放的过程进行了研究。3个采样点的汞释放通量日均值分别为559．1、88．2、53．6ng·m^-2·h^-1，汞释放通量强度与表层基质中的汞含量密切相关，该测定值高于世界背景地区通量的1-2个数量级，说明封闭垃圾填埋场也是大气汞的潜在来源。汞释放通量呈现明显的昼夜变化规律，白天较高并在午间前后达到最大，而夜间降至最低。气相因子中光照强度与汞的释放过程相关性最高，其次分别是气温、相对湿度、地温和风速。氧化态汞的光致还原作用是可能垃圾填埋场Hg^0生成的主要途径，降雨初期能促进地表汞的释放。