脑蛋白水解物中氨基酸的柱前衍生高效液相色谱测定

通过升高色谱柱温度,结合线性梯度洗脱的分离模式调整色谱分离的选择性,提出了一种测定脑蛋白水解物注射液中氨基酸含量的2,4-二硝基氟苯(DNFB)柱前衍生高效液相色谱方法。本法采用Kromasil C18(250×4.6 mm i.d.,5μm)色谱柱,柱温44℃,在30 min内以3个线性梯度能完全分离17种氨基酸,定量线性范围为0.2~1.0mg/L;加标回收率为89%~108%。该法具有适用性好、稳定性高等特点,也可以应用于其它种类样品中氨基酸的测定。     

纳米镍-铁合金/膨胀石墨复合材料的制备、表征及其电磁屏蔽性能

The composites with nano-particles of Ni-Fe alloys dispersed on the nano-layers of expanded graphite (EG) were prepared by the impregnation of EG with ethanol solutions of nickel and iron acetates， followed by drying and reduction in H₂. The square nano-particles of Ni-Fe alloys with particle sizes of mainly 20～40 nm were found to be well spread on the layers of EG. The alloy nano-particles exhibited high shielding effectiveness (SE) for electromagnetic radiations at low frequencies due to their high magnetic conductivity. Since EG is electronically conductive and displayed high SE at high frequencies， the composites exhibited good SE at wide range of frequencies. The electric and magnetic conductivities of the composites could be monitored through regulating the loadings of alloy nano-particles on EG， and it was found that the composites with 20%～40% of the alloys exhibited good SE. Specifically， the composite 27%Ni-3%Fe-EG showed the excellent SE from 66 to 110 dB at the frequencies from 300 kHz to 1.5 GHz.     

利用聚合物乳液合成聚甲基丙烯酸甲酯/二氧化硅纳米杂化材料

通过正硅酸乙酯分别在聚甲基丙烯酸甲酯乳液和四氢呋喃溶液中的溶胶－凝胶反应制备出不同的聚甲基丙烯酸甲酯／二氧化硅复合材料。利用扫描电镜、透镜电镜、差热分析和热失重对试样进行了分析。结果表明，利用聚合物乳液可以获得纳米分散的聚甲基丙烯酸甲酯／二氧化硅复合材料，并且在某种程度上其分散尺度小于利用聚合物溶液获得的复合材料。同时，利用聚合物乳液来制备聚甲基丙烯酸甲酯／二氧化硅杂化材料更有利于凝胶过程中二氧化硅网络的形成。     

PS-b-P2VP/Fe_3O_4纳米复合材料的制备与表征

采用油酸表面改性的粒径均一的Fe3O4磁性纳米粒子(OA-Fe3O4)与具有微相分离结构的聚苯乙烯-b-聚2-乙烯基吡啶(PS-b-P2VP)嵌段共聚物通过溶液共混,得到具有超顺磁性的PS-b-P2VP/Fe3O4纳米复合材料.结果表明,在OA-Fe3O4质量分数为1%,3%,5%和10%时,纳米粒子分散在PS相区;但OA-Fe3O4含量为8%时,纳米粒子在嵌段聚合物基体中的分散状态发生突变,形成大尺寸聚集体并分散在整个基体中,此时复合材料的流变行为发生相应变化.     

Synthesis and Rheological Investigation ofModel Symmetric 3-Arm Star Polyethylene简

A variety of linear and 3-arm star polyethylene （PE） model polymers covering a wide range of molecular weight are synthesized by the living polymerization of butadiene and the subsequent hydrogenation. Several rheological parameters of these model linear and 3-arm star PE samples are analyzed for detecting the long chain branching （LCB） structure. It is found that the analyses based on zero shear viscosity, vGP plot and flow activation energy are very sensitive to the 3-arm star PEs. The information on the presence of LCB can be obtained with these methods even for low molecular weight samples, which can not be determined by GPC-MALLS. However the information about the LCB structure can not be obtained by the rheological methods alone.     

Synthesis of Star-like Polybutadienes by a Combination of Living Anionic Polymerization and “Click” Coupling Method

Three-arm and four-arm star-like polybutadienes(PBds) were synthesized via the combination of living anionic polymerization and the click coupling method. Kinetic study showed that the click reaction between the azido group terminated PBd-t-N3 and the alkyne-containing multifunctional linking reagent was fast and highly efficient. All coupling reactions were fully accomplished within 40 min at 50 °C in toluene in the presence of the reducing agent Cu(0), proven by 1H-NMR, FTIR and GPC measurements. For the coupling reactions between the PBd-t-N3 polymer and dialkyne-containing compound, the final conversion of the coupled PBd-PBd polymer was ca. 97.0%. When a PBd-t-N3 polymer was reacted with trialkyne-containing or tetraalkyne-containing compound, the conversion of three-arm or four-arm PBd was around 95.5% or 87.0%, respectively. Several factors influencing the coupling efficiency were studied, including the molecular weight of the initial PBd-t-N3, arm numbers and the molar ratio of the azido group to the alkynyl group. The results indicated that the conversion of the target products would be promoted when the molecular weight of the PBd-t-N3 was low and the molar ratio of the azido to alkynyl groups was close to 1.     

C18-磺酸基双改性液相色谱固定相的制备与评价

以十八烷基三氯硅烷和3-巯丙基三甲氧基硅烷为改性剂,采用一锅法对硅胶表面加以修饰,进一步将巯基氧化制备成C18-磺酸基双改性液相色谱固定相.在优化的反应条件下得到了十八烷基和磺酸基摩尔比为3∶7的固定相,分别采用扫描电镜、元素分析、红外光谱对固定相的形貌和特征加以表征.针对制备的固定相,在不同的分离模式下,系统考察其色谱分离性能.在反相色谱模式下,成功分离了5种烷基苯化合物;在亲水模式下,分离了3种核苷;进一步应用于牛血清白蛋白酶解产物的分离,得到了较好的结果.实验结果表明,制备的混合模式固定相同时具有多种分离机理,在分离复杂样品、调整选择性方面具有潜在的优势.     

折叠波导行波管切断匹配的设计

 利用电磁模拟软件,计算得到了H面渐变与E面渐变的楔形衰减器匹配效果,指出在相同渐变长度下,E面渐变匹配效果优于H面渐变。H面渐变衰减器反射主要来源于电场集中处,而E面渐变衰减器主要来源于渐变前部尖端处。在此基础上设计出了一种变形的匹配衰减器,即在E面渐变衰减器渐变开始处向前延伸一块薄片。计算结果与测试结果表明:与H面渐变和E面渐变的楔形衰减器相比,所设计衰减器在近截止频率处的匹配效果得到了明显的改善。     

Poly(vinyl alcohol)/GO-MMT nanocomposites: Preparation,structure and properties

A facile, efficient and environment friendly method is established to prepare poly(vinyl alcohol)(PVA) based graphene oxide-montmorillonite(GO-MMT) nanocomposites in aqueous media. GO-MMT nanohybrid is obtained by the combination of GO and MMT in water without any reducing or stabilizing agents. The formation of GO-MMT nanohybrid is due to the hydrogen bonding and crosslinking effects. The sodium ions within MMT sheets act as crosslinkers between GO sheets and MMT platelets. The resultant nanocomposites are characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM), differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and mechanical testing. Compared to that of pure PVA, PVA nanocomposites show enhanced thermal stabilities and mechanical properties, which results from strong interfacial adhesion of the nanoadditives in PVA matrix. The further increase in the tensile strength and modulus results from strong interaction between PVA chains and layered GO-MMT as well as good mechanical properties of GO-MMT hybrid, compared to PVA/GO and PVA/MMT nanocompsoites.     

超分子溶剂直提测定水中的多环芳烃

超分子溶剂是两亲化合物通过分子间有序的自组装过程形成的具有纳米结构的胶束聚集体,是一种高效提取溶剂。该文以高效液相色谱-荧光检测法为测试手段,系统地对超分子溶剂组成及用量进行了优化,发展了一种直接提取、快速测定水中多环芳烃的方法,并进行了方法学验证及实际样品检测。结果表明,采用四氢呋喃和1-辛醇制备的超分子溶剂对4种多环芳烃的回收率为89.08%~102.47%,相对标准偏差(RSD,n=5)为1.38%~3.92%。4种多环芳烃在一定范围内线性关系良好(相关系数R~20.999),检出限为1.26~9.23 ng/L。该方法前处理过程简单,有利于实现快速分析;溶剂使用量少,符合绿色化学的发展趋势,具有一定的推广价值。