Microstructure characterization of short-chain branching polyethylene with differential scanning calorimetry and successive selfnucleation/annealing thermal fractionation

A series of the copolymers of ethylene with 1-hexene(M1–M9) synthesized by metallocene catalyst Et[Ind]2ZrCl2/MAO was studied by differential scanning calorimetry and successive self-nucleation and annealing(SSA) thermal fractionation. The distribution of methylene sequence length(MSL) in the different copolymers was determined using the SSA method. The comonomer contents of samples M4 and M5 are 2.04 mol% and 2.78 mol%, respectively. Both M4 and M5 have low comonomer content and their MSL distribution profiles exhibit a monotonous increase trend with their MSL. The longest MSL of M5 is 167, and its corresponding molar percent is 43.95%, which is higher than that of M4. Moreover, the melting temperature(Tm) of M5 is also higher than that of M4. The comonomer contents of samples M7, M8, and M9 are 8.73 mol%, 14.18 mol% and 15.05 mol%, respectively. M7, M8, and M9 have high comonomer contents, and their MSL distribution profiles display unimodality. M7 has a lower peak value of 33 and a narrow MSL distribution, resulting in a Tm lower than that of M8 and M9. The MSL and its distribution are also key points that influence the melting behavior of copolymers. Sometimes, MSL and its distribution of copolymers have a greater impact on it than the total comonomer contents, which is different from traditional views.     

差示扫描量热法测定比沙可啶的纯度

建立差示扫描量热法测定比沙可啶原料药样品纯度的方法。考察了炉体气氛、升温速率、称样量3个因素对差示扫描量热法测定结果的影响,确定差示扫描量热法最佳实验条件:升温速率为2.0 K/min,称样量为2.0~4.0 mg,炉内气体为静态空气。差示扫描量热法测定比沙可啶样品纯度为99.86%,测定结果的相对标准偏差为0.02%(n=6),差示扫描量热法测定比沙可啶样品纯度值与HPLC测定结果具有良好的一致性。该方法可以快速、准确地测定比沙可啶化学纯度,为比沙可啶纯度测定提供了一种新的分析方法。     

上转换发光免疫试纸条扫描检测系统研究

研制了一种以上转换发光材料作为标记物的扫描检测系统,有别于传统的测量方法,可做出定量和多重分析.扫描检测系统以扫描方式逐点测量经生物反应而结合上去的UCP颗粒的含量,记录整个免疫试纸条的信息,计算出被测样品中特定生物分子的浓度.实验结果表明,该系统对兔抗鼠疫免疫球蛋白（IgG）标准样品的检测灵敏度达到百ng/mL量级,且具有变异系数小于6%的重复性,符合生物免疫测定的要求.     

扫描隧道显微镜研究石墨表面的莫尔图

Moir patterns on HOPG were studied with scanning tunneling microscopy (STM). The results reveal that the observed Moiré patterms originate from the defects locating several layers below the surface ,which presents the first experimental evidence supporting the prediction that in HOPG the nanoscale electronic waves can propagate through several layers without obvious decay.     

Fe(Ⅲ)-KIO4-苋菜红体系催化动力学单扫描示波极谱法测定痕量铁

研究了在H2SO4介质中,痕量Fe(Ⅲ)催化KIO4氧化苋菜红的褪色反应.提出了催化动力学单扫描示波极谱法测定痕量铁的新方法.在1.6×10-3mol/L H2SO4介质中,苋菜红在汞电极上产生1个还原峰,峰电位为-0.186 V(vs.SCE)左右.氧化剂KIO4存在时,在-0.186 V处的峰电流的降低与加入Fe(Ⅲ)离子在0～0.04μg/mL范围内呈良好的线性关系,检出限4.2×10-9g/mL.同时研究了该方法适宜的反应条件,应用本方法测定中草药和水中铁的含量,回收率在98%～101%之间,结果满意.     

兔主动脉冻结过程中未冻水份额的研究

利用差示扫描量热仪(DSC)技术中的分步扫描(Stepwise scanning)法,研究了不同浓度的低温保护剂对主动脉血管冻结过程中未冻水份额的影响。研究结果表明:分步扫描量热技术可以用于血管材料冻结过程中未冻水份额的定量研究,而且具有较高楠度;随着低温保护剂二甲亚砜(DMSO)浓度的增大,血管的初始冻结点温度呈线性降低,但其冻结过程的未冻水份额显著增大,这是由于高浓度DMSO具有很强水合能力所致。     

冻干溶液的低温显微研究与热分析

利用低温显微系统研究了叔丁醇水溶液降温时的晶体形态,并利用差示扫描量热法(DSC)研究了溶液的反玻璃化结晶。低温显微实验表明:叔丁醇／水溶液结晶形状、大小与叔丁醇的浓度有关,浓度为10％时形成粗大的针状结晶, 有利于升华速率的提高。DSC实验表明:10％叔丁醇／10％蔗糖／水三元溶液的临界复温速率为250℃／min左右。     

硝普钠-铜(Ⅱ)体系的极谱法研究与应用

本文用单扫描极谱法研究了硝普钠(SNP)-铜(Ⅱ)体系的伏安行为。在pH3.0的克拉克-鲁布斯缓冲溶液中,SNP和SNP-Cu2 体系于-0.47 V(vs.SCE)处均有极谱还原峰,但SNP-Cu2 体系的灵敏度是SNP的100倍左右,其峰高与SNP浓度在2.0×10-7~4.0×10-5mol/L范围内呈线性关系,检出限为1.0×10-7mol/L。应用本法测定静脉注射到大白鼠中SNP的含量,结果满意。     

Fe(Ⅲ)-KIO4-胭脂红体系催化动力学单扫描示波极谱法测定痕量铁的研究

本文研究了在H2SO4介质中,痕量Fe(Ⅲ)催化KIO4氧化胭脂红的褪色反应;提出了催化动力学单扫描示波极谱法测定痕量铁的一种新方法。在1.6×10-3mol/LH2SO4介质中,胭脂红在汞电极上产生一个还原峰,峰电位为-0.102 V(vs.SCE)。当氧化剂KIO4存在时,在-0.102 V处的峰电流的降低与加入Fe(Ⅲ)的含量在0~0.025μg/mL范围内呈良好的线性关系,检出限可达1.05×10-10g/mL。应用本法测定了蕨菜、黄芪中铁的含量,结果令人满意。     

呋喃丹的薄层扫描定量分析研究

采用双波长反射吸收薄层扫描法对呋喃丹进行了定量分析方法的研究。方法的线性范围为2~200μg,线性相关系数为0.997;呋喃丹的检出限为0.3μg,回收率为96.94%~100.38%,相对标准偏差为1.73%。本方法快速、简单、易行。