4-(2-吡啶偶氮)-间二苯酚光度法测定奶粉中的锌含量

研究了显色剂4-(2-吡啶偶氮)-间二苯酚与锌的显色反应.在pH=9.0的硼砂-盐酸缓冲溶液中,非离子表面活性剂OP存在下.锌与4-(2-吡啶偶氮)-间二苯酚反应形成红色配合物,其最大吸收波长为500nm,表观摩尔吸光系数为6.24×104L·,moL-1·cm-1.锌含量在0～60μg/50mL范围内符合比尔定律.该方法用于测定奶粉中的锌含量测定,加标回收率为97.8%～103.6%,相对标准偏差小于3.6%.     

4-(5-氯-2-吡啶)-偶氮-1,3-二氨基苯光度法测定电镀废水中的微量镍(Ⅱ)

4-(5-氯-2-吡啶)-偶氮-1,3-二氨基苯(5-Cl-PADAB)可与镍发生灵敏的显色反应,生成稳定的配位化合物。基于此建立了一种测定电镀废水中微量镍的光度法。结果表明:在2.0 mol/L HCl介质中,5-Cl-PADAB与Ni(Ⅱ)反应生成摩尔比2∶1的稳定配位化合物,其最大吸收波长为565 nm,表观摩尔吸光系数为6.42×104 L/(mol.cm),Ni(Ⅱ)含量在0～1.0 mg/L内符合比尔定律;该方法用于测定电镀废水中微量镍,结果与催化-分光光度法相符,相对标准偏差小于4.0%,加标回收率为98.5%～101.8%。     

化学共沉淀法制备γ′-(Fe_(1-x)Ni_x)_4N粉末的微结构及磁性研究

用化学共沉淀法和在NH3/H2气氛下氮化处理得到了一系列不同Ni含量的Fe-Ni-N多晶粉末。XRD测试的结果表明,随着Ni含量的增加,材料的晶格常数逐渐减小;制备出单相的γ′-(Fe1-xNix)4N条件主要与NH3/H2气流比、热处理温度及时间有关。从VSM测量的结果来看,随着Ni含量的增加,材料的饱和磁化强度(Ms)总体呈下降趋势。Ni含量在0.18-0.28之间较容易得到单相γ′-(Fe1-xNix)4N,并且磁性质比较稳定。通过研究不同Ni含量对磁性的影响,进一步分析了Ni的占位问题。     

用1-(2-苯并噻唑)-3-(3,5-二溴吡啶)-三氮烯荧光光度法测定电镀废水中的微量铜(Ⅱ)

目前,利用1-（2-苯并噻唑）-3-（3,5-二溴吡啶）-三氮烯（BTPYBT）与铜的荧光反应测定铜的研究未见报道。合成了BTPYBT,依据其与铜（Ⅱ）的荧光反应,建立了一种测定微量铜（Ⅱ）的新的荧光光度法。结果表明:在pH值9.2的Na₂B₄O₇-NaOH缓冲溶液中,该试剂与铜（Ⅱ）形成2:1稳定的配合物,体系的激发波长和发射波长分别为359 nm和401 nm;铜含量在0⁸0.0μg/L内与荧光响应值△F（配合物溶液和空白试剂荧光强度之差）呈良好的线性关系,其线性回归方程为△F=一0.177+1.19ρ,相关系数r=0.998 6,检出限为0.2μg/L,本方法用于测定电镀废水中的微量铜,与原子吸收光度法（AAS）结果相符,6次测定值的相对标准偏差小于3%,加标回收率为98.8%¹03.0%。     

4-(2-吡啶偶氮)-间二苯酚光度法测定奶粉中的锌含量

研究了显色剂4-(2-吡啶偶氮)-间二苯酚与锌的显色反应。在pH=9.0的硼砂-盐酸缓冲溶液中,非离子表面活性剂OP存在下,锌与4-(2-吡啶偶氮)-间二苯酚反应形成红色配合物,其最大吸收波长为500nm,表观摩尔吸光系数为6.24×104L·moL-1·cm-1。锌含量在0-60μg/50mL范围内符合比尔定律。该方法用于测定奶粉中的锌含量测定,加标回收率为97.8%-103.6%,相对标准偏差小于3.6%。     

化学共沉淀法制备γ''-(Fe1-xNix)4N粉末的微结构及磁性研究

用化学共沉淀法和在NH3/H2气氛下氮化处理得到了一系列不同Ni含量的Fe-Ni-N多晶粉末.XRD测试的结果表明,随着Ni含量的增加,材料的晶格常数逐渐减小;制备出单相的γ'-(Fe1-xNix)4N条件主要与NH3/H2气流比、热处理温度及时间有关.从VSM测量的结果来看,随着Ni含量的增加,材料的饱和磁化强度(Ms)总体呈下降趋势.Ni含量在0.18-0.28之间较容易得到单相γ'-(Fe1-xNix)4N,并且磁性质比较稳定.通过研究不同Ni含量对磁性的影响,进一步分析了Ni的占位问题.     

乳化液膜的制备及其在1-萘酚废水处理中的实验研究

在较低的转速下(720 r/min),将磁力搅拌和超声方法结合,制备煤油-Span80-NaOH乳化液膜,在较温和条件下制备了稳定性较高的乳化液膜.将制备的乳化液膜应用于1-萘酚废水溶液的处理.系统考察了液膜制备过程的影响因素,如NaOH浓度、超声时间、油内比等;废水处理的操作条件:外水相pH、接触时间和乳水体积比等因素对1-萘酚的去除效果.结果表明,NaOH浓度为2％、超声时间为5 min、油内比为1∶2、无需调节pH、接触时间为15min、乳水比为1∶5时,1-萘酚去除率可高达94％.     

增效试剂在动力学分析法中的应用研究锰(Ⅱ)—高碘酸钾—氨三乙酸—PAN—Triton X—100催化体系

本文报道了以 Triton X—100为增溶剂,高碘酸钾氧化 PAN 催化光度法测定痕量锰的新体系。方法的检出限为3.6×10~(-3)μg/mL,精密度为2.4%(n=9),线性范围为0.10～1.3μg/25mL,可用于谷物样品中锰的测定。     

纳米晶 Ni1-x ZnxFe2O4铁氧体粉料的制备及其磁性能研究

采用喷射-共沉淀法制备了纳米晶Ni1-xZnxFe2O4（0≤x≤1.0）铁氧体粉料.通过TG-DSC、XRD、SEM、TEM、BET等测试手段分析了其微观结构和形貌,用振动样品磁强计测量其室温下磁性能.结果表明：喷射-共沉淀法制备的粉料颗粒细小均匀、形状完整.600℃下煅烧1.5h,样品晶粒尺寸为30nm左右,平均颗粒尺寸＜100nm.室温下,样品比饱和磁化强度随Zn^2＋含量增加而变化,当x=0.5时,最大比饱和磁化强度σs为66.8A·m^2/kg.当晶粒大小为41nm时,纳米晶Ni0.5Zn0.5Fe2O4铁氧体矫顽力达到最大值5.06kA/m,随后又随晶粒尺寸增大而减小.这归因于纳米晶软磁材料中强烈的无序磁晶各向异性模式的影响.     

碳纤维用聚丙烯腈新型共聚物的制备

通过采用丙烯腈、衣康酸、甲基丙烯酸正丁酯共聚合方法合成了一种新型聚丙烯腈共聚物。通过改变引发剂的用量、反应温度、单体配比等 ,确定了最佳反应条件 ,合成的粘均分子量为 2 70×1 0 5的新型共聚物 ,可用于碳纤维的研究     

PVC/PAN共混膜的制备与性能

采用溶液相转化法制备了聚氯乙烯(PVC)/聚丙烯腈(PAN)共混膜,研究了(PVC)/(PAN)共混体系的相容性,并通过红外光谱(FT-IR)、扫描电子显微镜(SEM)等对PAN水解前后共混膜结构、形貌和性能进行了表征与分析。结果表明,(PVC)/(PAN)为部分相容体系,在成膜过程中产生明显界面微孔结构;共混膜中的PAN发生水解后,生成大量酰胺、羧酸、羧酸盐等亲水基团,改善了共混膜的亲水性(膜的水接触角从87.48°降低到65.12°),提高了共混膜的通透性(膜的纯水通量从84.17 L/(m2.h)升高到343.7 L/(m2.h))。     

以PAN为基膜的复合纳滤膜的制备研究

以NaOH溶液改性后的聚丙烯腈(PAN)超滤膜为基膜,对,对′-二氨基二苯甲烷(DDM)和均苯三甲酰氯(TMC)为单体,经过界面聚合反应制备复合纳滤膜。考察了胺浓度、酸接受剂浓度、界面聚合时间等对膜分离性能的影响。结合FTIR和环境扫描电镜(ESEM)研究复合膜的表面形态及断面结构,讨论了复合纳滤膜致密层的结构与其性能的关系。结果表明,采用界面聚合反应在PAN改性膜上已复合一层致密的表皮层,该致密表皮层是聚酰胺结构。     

Preparation of aminated-polyacrylonitrile nanofiber membranes for the adsorption of metal ions: comparison with microfibers

Polyacrylonitrile nanofibers (PAN-nFs) were produced using the electrospinning method. Subsequently, the electrospun fibers were modified by diethylenetriamine to produce aminated polyacrylonitrile (APAN) nanofibers. Finally, the adsorbability of copper ions on the surface of the nanofibers was examined in an aqueous solution. Attenuated total internal reflection (ATIR) analysis confirmed the surface amination of the produced PAN-nFs. The grafting yield was calculated by the gravimetric method. The optimum condition was determined to yield the maximum grafting of amine groups to PAN with no losses in sample flexibility. Atomic absorption spectroscopy (AAS) was used to measure the copper ion concentration in the solution. Results indicate that the adsorption process in nanofibers is three times faster in comparison with microfibers. Moreover, the pH effect was studied based on the adsorption behavior of copper ions on the APAN nanofibers. In addition, thermodynamic parameters were calculated, revealing that the process was endothermic and demonstrating that randomness increased at the solid-solution interface during the process. The obtained enthalpy value indicates that the chelation of copper ions among the aminated polyacrylonitrile can be regarded as a chemical adsorption process. The adsorption data fit well with the Langmuir isotherm. The saturation adsorption capacity obtained from the Langmuir model for Cu(II) ions was 116.522 mg/g which is five times more than the reported value for APAN microfibers [S. Deng, R. Bai, J.P. Chen, Aminated polyacrylonitrile fibers for lead and copper removal, Langmuir,19 (2003)5058-5064]. Analysis using atomic force microscopy (AFM) showed that the surface roughness increased upon adsorption of the metal ion. Scanning electron microscopy (SEM) examination demonstrated that there were no cracks or sign of degradation on the surface after amination.     

牵伸对湿纺聚丙烯腈纤维性能的影响

研究了牵伸对湿纺聚丙烯腈(PAN)纤维性能的影响,发现初期形成的PAN纤维的应力-应变曲线是典型的非晶高聚物应力-应变曲线,随着牵伸的进行,纤维应力-应变曲线的屈服点逐渐消失;牵伸对湿纺PAN纤维的性能具有主要影响,随着牵伸倍数的提高,纤维的线密度、断裂伸长率下降,强度增加.     

阳极磁屏蔽霍尔离子源磁场的数值模拟

为了提高离子束电流和离子束能量,进一步增加霍尔离子源的效率,对霍尔离子源阳极进行磁屏蔽,达到优化磁场位形,增强磁场对放电等离子体的约束。由磁场的数值模拟结果可知:阳极磁屏蔽后,有明显凸向阳极表面的弯曲磁场线,并且提高了磁镜磁场的磁镜比;大的正梯度磁场的存在,增强了磁场的径向分量,相对减弱了放电等离子体的震荡;不仅保留原有鞍形场的作用,而且还充分发挥了另外两个鞍形场的优势。最后通过实验结果和数值模拟结果的比较,验证了此数值模拟结果的正确性。     

静电纺丝法制备聚丙烯腈基纳米炭纤维及其表面结构表征

通过稳定化、炭化静电纺制的聚丙烯腈(PAN)前驱体纤维制备了直径为100nm～300nm的纳米炭纤维.用扫描电镜(SEM)、场发射扫描电镜(FESEM)、扫描隧道显微镜(STM)及扫描量热分析法(DSC)研究了纳米炭纤维及其前驱体纤维的形貌及结构.结果表明:纳米炭纤维及其前驱体纤维的直径表现为对数正态分布.静电纺制纤维的环化放热峰移向低温,表明静电纺制纤维可在较低的温度下引发环化.由于静电纺制纤维的粗糙表面及在热处理过程中的收缩行为,在纳米炭纤维表面形成了长度为10nm宽度为5nm的凹坑.     

聚丙烯腈(PAN)/TiO2超细纤维的制备与表征

利用静电纺丝法,采用TiO2凝胶实现了聚丙烯腈(PAN)/TiO2超细纤维的制备。应用TEM、SEM、红外光谱、X射线衍射光谱等方法对其进行了理化性能表征,并测试了其对金黄色葡萄球菌的抗菌性能。结果表明:随PAN溶液与TiO2凝胶质量比的降低,电纺纤维尺寸较均匀,珠状物逐渐减少;该比率(PAN溶液∶TiO2凝胶)为3.5∶1时对金黄色葡萄球菌的抗菌率达到82%。由此制备的超细纤维有望用于过滤膜、防护服及医用敷料等纺织材料领域。     

Selective activation of mechanosensitive ion channels using magnetic particles.

This study reports the preliminary development of a novel magnetic particle-based technique that permits the application of highly localized mechanical forces directly to specific regions of an ion-channel structure. We demonstrate that this approach can be used to directly and selectively activate a mechanosensitive ion channel of interest, namely TREK-1. It is shown that manipulation of particles targeted against the extended extracellular loop region of TREK-1 leads to changes in whole-cell currents consistent with changes in TREK-1 activity. Responses were absent when particles were coated with RGD (Arg-Gly-Asp) peptide or when magnetic fields were applied in the absence of magnetic particles. It is concluded that changes in whole-cell current are the result of direct force application to the extracellular loop region of TREK-1 and thus these results implicate this region of the channel structure in mechano-gating. It is hypothesized that the extended loop region of TREK-1 may act as a tension spring that acts to regulate sensitivity to mechanical forces, in a nature similar to that described for MscL. The development of a technique that permits the direct manipulation of mechanosensitive ion channels in real time without the need for pharmacological drugs has huge potential benefits not only for basic biological research of ion-channel gating mechanisms, but also potentially as a tool for the treatment of human diseases caused by ion-channel dysfunction.     

金属—PAN—S配合物的极谱研究——Ⅱ:Fe~(3+)—PAN—S—TEA—NH_3·H_2O—NH_4Cl体系配合吸附波

在NH_3·H_2O—NH_4Cl—三乙醇胺底液中Fe(Ⅲ)与PAN—S产生一灵敏的配合吸附波,峰电位在—0.50伏(vs.SCE)。峰电位与铁离子浓度在2.8×10~8～3.4×10~(-6)mol/L范围内线性良好,检出下限可达2.8×10~(-8)mol/L。该法用于乳粉、头发、血清等样品的测定,结果满意。