溶剂萃取PAN光度法测定茶叶水中铁形态

建立了溶剂萃取PAN光度法测定茶叶中铁形态的新方法。显色剂PAN与铁(Ⅱ)在pH1的介质中络合显色,Fe(Ⅲ)在此酸度下不显色,以甲基异丁酮为萃取剂,将Fe2 -PAN萃取到有机相,实现铁(Ⅱ)和Fe(Ⅲ)的分离。文中详细研究了铁(Ⅱ)的显色和萃取条件:在pH1.0显色10 m in后,用5 mL的甲基异丁酮振荡萃取15 m in,分液后测定机相的吸光度。体系中加入还原剂,测定总铁的量。铁在0~20μg/5mL范围内呈线性关系,摩尔吸光系数为1.51×104L.mol-1.cm-1。该法用于测定茶叶水中的形态铁结果令人满意。     

PAN树脂的制备及PAN树脂-微色谱柱分离富集ICP-AES法测定镉的研究

研究了PAN树脂的制备和PAN树脂—微色谱柱对镉的分离富集 ,然后用ICP -AES法测定镉。试验结果表明在pH10的缓冲溶液 (NH3 ·H2 O -NH4Cl)介质中 ,镉被树脂吸附 ,而样品中碱金属、碱土金属不被吸附 ,可用蒸馏水淋洗除去。再用 5mLφ =10 %热盐酸可完全解吸镉等元素 ,用ICP -AES法无干扰地测定ng·g-1级镉元素。     

Thermal conductivity and thermal expansion behavior of pseudo-unidirectional and 2-directional quasi-carbon fiber/phenolic composites

In the present paper, a variety of fiber reinforcements, for instance, stabilized OXI-PAN fibers, quasi-carbon fibers, commercial carbon fibers, and their woven fabric forms, have been utilized to fabricate pseudo-unidirectional (pseudo-UD) and 2-directional (2D) phenolic matrix composites using a compression molding method. Prior to fabricating quasi-carbon fiber/phenolic (QC/P) composites, stabilized OXI-PAN fibers and fabrics were heat-treated under low temperature carbonization processes to prepare quasi-carbon fibers and fabrics. The thermal conductivity and thermal expansion/contraction behavior of QC/P composites have been investigated and compared with those of carbon fiber/phenolic (C/P) and stabilized fiber/phenolic composites. Also, the chemical compositions of the fibers used have been characterized. The results suggest that use of proper quasi-carbonization process may control effectively not only the chemical compositions of resulting quasi-carbon fibers but also the thermal conductivity and thermal expansion behavior of quasi-carbon fibers/phenolic composites in the intermediate range between stabilized PAN fiber- and carbon fiber-reinforced phenolic composites.     

1-(2-吡啶偶氮)-2-萘酚与牛血清白蛋白相互作用研究

用荧光光谱法结合紫外可见吸收光谱法、圆二色谱法(CD)研究了1-(2-吡啶偶氮)-2-萘酚(PAN)与牛血清白蛋白(BSA)的相互作用。研究表明,PAN与BSA发生了生成复合物的静态猝灭作用;紫外可见吸收光谱辅证了PAN对牛血清白蛋白的猝灭机制属于静态猝灭;利用Van’t Hoff方程计算体系的热力学参数焓变(ΔH)和熵变(ΔS),ΔH和ΔS的值均小于0,表明两者主要以氢键和范德华力作用力结合;圆二色谱法研究表明,PAN指示剂引起BSA二级结构的改变。     

Homogeneity of the PAN/DMSO/H2O spinning solutions

The homogeneity of PAN/DMSO/H₂O spinning dopes with conventional PAN molecular weight and comparative high PAN concentration have been investigated using rheology method. The rheological results show that G′ and G″ of these solutions increase with increasing oscillation frequency. At lower temperature and higher H₂O content, higher viscous modulus and elastic modulus are observed, too. The homogeneity of PAN/DMSO/H₂O systems is reflected through the logG′-logG″ plots as well as gel point temperatures. The theoretical analysis indicates PAN/DMSO/H₂O spinning solutions with conventional PAN molecular weight are close to homogeneous systems, which are very suitable for gel spinning.     

Preparation and characterization of modified collagen/PAN blending fibers

Graft modification of collagen with acrylonitrile in concentrated aqueous solution of sodium thiocyanate (NaSCN) is developed in this paper. This modification can largely change it’s solubility in water and can be applied in fiber production. Grafting modified collagen is characterized by infrared spectrum and wide angle X-ray diffraction. Wet spinning of PAN fibers containing several content of modified collagen is performed. The tests about these fibers show that breaking strength and sonic orientation decrease as the amount of collagen is raised. The addition of collagen can largely improve the moisture regain of PAN fiber. Micro-appearance of fibers observed under scanning electron microscope (SEM) presents circular cross section and longitudinal grooves on surface, the depth of grooves increases with the increasing draw ratio.     

分光光度法测定伏牛山荷叶中微量元素锌

[目的]测定荷叶（FOLIUMNELUMBINIS）中微量元素锌的含量,为荷叶在医药及食品工业的深度开发利用提供科学依据。[方法]采用直接分光光度法,以1-（2-吡啶偶氮）-2-萘酚（PAN）为显色剂、锌标准液为对照品,在562 nm波长处测定吸光度。[结果]Zn（Ⅱ）与PAN形成红色的络合物,在0.48~5.03μg/ml范围内,吸光度值与含量线性关系良好（r=0.999 9）;平均回收率为99.8%,RSD为0.34%。伏牛山荷叶中锌元素的平均含量为87.44μg/g,RSD为1.02%。[结论]该方法简便、准确、重现性好,稳定性高,可用于荷叶中微量元素锌含量的测定。     

5个番石榴品种在南宁地区的引种试种初报

为给南宁地区引进番石榴优良品种并进行规模化推广栽培提供理论依据和技术支撑,对珍珠番石榴、西瓜番石榴、红宝石番石榴等5个番石榴品种的植株生长表现与植物学特征、农艺性状、果实品质性状进行了对比研究。结果表明,珍珠番石榴、红宝石番石榴、西瓜番石榴丰产稳产,口感酥脆、甜酸适宜,品质优,适合在南宁地区推广栽培;西瓜2号番石榴产量高,果肉嫩滑,口感好,但不耐储运;水晶无籽番石榴果肉酥脆,甜度适中,但产量低;因此,西瓜2号番石榴和水晶无籽番石榴不建议在南宁地区推广规模化栽培。