Preparation and properties of polyurethane networks based on α,ω-difunctional poly(hexafluoropropylene oxide)

Poly(hexafluoropropylene oxide), poly(HFPO), networks were prepared from functional polymers by end linking via urethane groups. The prepolymers were characterized by NMR spectroscopy and GPC. The networks were characterized by determination of the number of network chains from the shear modulus, and were snown to contain both trifunctional crosslinks and difunctional links. The properties of the networks were investigated by a range of techniques. Compared with fully-fluorinated networks formed via triazine cross-links, investigated previously, the urethane-linked networks were more readily prepared but were poorer elastomers, were less thermally stable, and were less resistant to swelling by common polar solvents. © 1995 John Wiley & Sons, Inc.     

南瓜籽烘烤前后化学成分的分析

对烘烤前后南瓜籽中的化学成分进行分析并对比。采用同时蒸馏萃取装置萃取南瓜籽中的挥发性成分,采取超临界CO2萃取技术萃取南瓜籽油脂,并将其分为酸、碱、中性三个部分,用气相色谱-质谱联用方法分析其中化学成分并进行对比。结果表明,南瓜籽挥发性成分中含有多种醛类和酯类化合物,烘烤后产生了大量的烷基吡嗪,其在碱性部分中的相对含量比烘烤前提高14倍多,不饱和醛类化合物含量也有明显提高。南瓜籽油脂中的主要化学成分是油酸、亚油酸及其酯类。还含有生物活性功能成分如植物甾醇、角鲨烯和维生素E等。烘烤后除角鲨烯含量有所降低,维生素E、植物甾醇、亚麻酸等均有提高。     

IClO2异构化反应机理及电子密度拓扑研究

利用密度泛函理论方法研究了IClO2异构化反应机理. 优化得到了七种异构体, 其中OIClO和IClOO还未见报道, 对各异构体的热力学稳定性进行了比较. 找到了异构化过程的过渡态, 并通过内禀反应坐标(IRC)计算确认了各个异构体之间的相互转化关系. 从量子拓扑学的角度, 对典型异构化反应通道IRC途径上的各点进行了电子密度拓扑分析, 讨论了反应过程中化学键的断裂、生成以及化学键的变化规律, 找到了反应途径上的能量过渡态(ETS)和结构过渡态(STS).     

云南菊科中草药中铅含量特征分析

论述了云南２７种菊科中草药及其水提取物中铅含量的特征。菊科植物及水提物中铅含量的频数分布为正偏态,两者的相关系数ｒ＝０．０９,未呈现显著的线性相关。提取率较高的山紫苑、佩兰、木香铅实际含量低;铅含量高的叶下花、狭叶兔耳风、臭灵丹提取率又较低,减少了人体对Ｐｂ的过量摄入。     

Reversed-phase high-performance liquid chromatographic, gel electrophoretic and size exclusion chromatographic studies of subunit structure of arachin and its molecular species

Arachin and its molecular species (arachin I and arachin II) were separated and isolated. The number and kind of subunits of arachin, arachin I and arachin II were determined. Studies were carried out under different experimental conditions using slab gel electrophoresis, size-exclusion chromatography and reversed-phase high-performance liquid chromatography. Gel electrophoresis was done under varying concentrations of resolving gel. Tube gel as well as slab gel electrophoresis were used and continuous as well as discontinuous buffer systems were used for both types of electrophoresis. In addition, the subunits were separated by reversed-phase HPLC using a gradient program. Arachin and arachin II were found to have 12 subunits each while arachin I showed six subunits. The subunits of arachin I were allowed to reconstitute by removing SDS. Eight combinations were tried for studying the reconstitution pattern. Molecular weight and weight ratio in each case were also determined.     

膜催化研究II. 多孔无要膜的制备与表征及其反应器对甲醇脱氢反应的促进作用

采用溶胶-凝胶法制备了多孔氧化铝膜, 并通过DSC、TGA、SEM、N~2吸附和气体透过率测定等手段, 对膜的性能进行了表征。结果表明, 用这种方法制备的多孔氧化铝膜是一种均匀无裂痕和具有较窄孔径分布(约4nm)的膜材料。将此多孔氧化铝膜制成膜反应器后, 用于甲醇催化脱氢制甲醛的反应, 发现甲醇转化率比常规反应器有较大幅度的提高。同时首次尝试采用溶胶-凝胶法将催化活性组分直接负载到多孔氧化铝膜上, 从而得到了一种具有催化活性的多孔膜, 并考察了它的反应活性。文中对由这两种多孔膜及钯/陶瓷复合膜制成的反应器的特点进行了比较。     

碳苷研究 V: 用Grignard试剂合成取代苯酚中酚羟基的保护及脱保护

本文报道了一些取代苯酚的合成, 并探讨了用Grignard试剂合成取代苯酚中酚羟基的保护及脱保护的问题. 利用苄基和甲基作为酚羟基的保护基, 对文献报道的切断醚键脱保护方法进行了评价. 找到了两种新体系能在更温和条件下切断醚键的方法, 指出了它们的适用条件. 实验结果符合硬软酸碱理论.     

等离子体发射光谱法测定茶水中无机元素的含量

采用电感耦合等离子体发射光谱法对茶水中的无机元素进行分析,对其中的Cu、Zn、Mn、P、Fe5种元素进行定量,讨论了等离子体发射光谱法最佳实验条件及影响茶叶中无机元素浸出量的因素。Cu、Zn、Mn、P、Fe的回收率为92．5％～103．5％,测定结果的相对标准偏差为1．34％-4．5％（n=5）。     

Trace elements in Taiwanese diet in different seasons

The trace element contents of Taiwanese diet were determined using conventional neutron activation analysis. Sample were prepared with duplicate portion technique by collecting food items ate and drank during a 3 day period in winter. Samples were homogenized, freeze-dried, and elemental concentration of trace elements were determined by instrumental neutron activation analysis. The interference from fast neutron induced reactions were corrected. Concentrations and daily dietary intake of the elements were compared with those collected in the summer, resulting less daily intake of K, Ca, Mn, Fe, and Zn among Taiwanese than the values recommended by WHO and RDA. Alarming low intake of Fe for females and Zn among Taiwanese were indicated.     

Manipulation of protein fingerprints during on-column fluorescent labeling: protein fingerprinting of six Staphylococcus species by capillary electrophoresis

Bacterial proteomes were analyzed by use of electrophoretically mediated microanalysis (EMMA) and field-enhanced stacking. A water-soluble protein fraction was injected onto a capillary. Next, a fluorogenic reagent was injected and allowed to react with the protein mixture, producing fluorescent products that were separated by submicellar capillary electrophoresis and detected by laser-induced fluorescence. By use of a low-ionic strength sample buffer and a brief electrophoretic step, slow moving anionic proteins were stacked at the reagent-sample interface and were preferentially labeled. By reversing the order of sample injection and labeling reagent, fast moving cationic proteins were preferentially labeled. By adjustment of the sample buffer pH, proteins with different isoelectric points were selectively labeled. Electrophoresis fingerprints were generated for the water-soluble protein fraction from six Staphylococcus species. The protein patterns produced were species-specific and were used to construct a phylogenetic tree.     

电感耦合等离子体质谱(ICP-MS)法测定玻纤滤筒中金属元素本底值的预处理方法探讨

探讨了不同预处理方法对国产玻纤滤筒本底值的降低效果,便于废气样品的分析测定。分别对空白滤筒、热硝酸、硝酸+硫酸和硝酸+EDTA、HCl处理后的滤筒进行分析,测得滤筒中金属元素的含量;对处理效果较好的一批滤筒进行空白加标,考察加标回收率,全程用电感耦合等离子体质谱(ICPMS)法对样品进行测定,结果发现空白滤筒中部分金属元素含量较高;热硝酸处理后,滤筒本底中铅含量有所降低,但其它元素去除效果不显著;硝酸+硫酸处理后,滤筒中铅含量剧增;硝酸+EDTA处理滤筒,铅可以得到较好的去除效果,大部分金属元素含量有了明显降低;基于HCl对金属有较好的溶出效果,浸泡可较好地降低滤筒中金属元素的含量,但大量氯离子存在对ICP-MS法测定的干扰较大。对硝酸+EDTA处理后的滤筒进行空白加标,大部分金属元素加标回收率75%。故以硝酸+EDTA处理玻纤滤筒可以使国产玻纤滤筒适用于废气样品的分析。     

Using fast gas chromatography-mass spectrometry with auto-headspace solid-phase microextraction to determine ultra trace residues of organophosphorus pesticides in fruits

Organophosphorus pesticides (OPs) in apple and tomato were determined by using fast gas chromatography-mass spectrometry (FGC-MS) coupled with auto-headspace solid-phase microextraction (SPME). The experimental conditions of FGC were investigated and developed. Three different fibers were studied and compared and it was found that the polydimethysiloxane (PDMS) was the best. Factors affecting the extract efficiency, such as extraction time, temperature, ion strength, agitator speed, and content of organic solvents, were investigated and optimized. The limits of detection (LOD) of OPs were achieved between 0.002 ng/g and 0.955 ng/g; the RSD was less than 20.9%, and the recoveries were from 79% to 117%. For most commercial fruit samples, ultra trace residues of OPs were found, mainly on the surface, and their concentrations were generally lower than LOD of conventional methods.     

幼儿身高、体重和头发、血液锌铅含量关系的研究

同步检测了151例3-4岁健康幼儿的身高、体重以及头和全血中的锌、铅含量。研究了身高、体重和锌、铅含量的关系,指出无论是发锌或血锌含量与身高、体重多数呈正相关,但发铅与身高、体重主要呈负相关,血铅与身高、体重的关系较为复杂,多为非线性的二次函数关系。     

芝罘湾表层沉积物中重金属的分布特征及潜在生态危害评价

为了解芝罘湾沉积物中重金属的污染状况,于2009年7月采集了黄海芝罘湾16个站位的表层沉积物并测定了其中的重金属含量.芝罘湾的重金属污染程度较低,所有测定值均低于国家海洋沉积物Ⅰ类质量标准.Hg、Cu、Pb、Cd、Zn、Ni、Co、Mn 8种重金属的平均含量分别为0.02、12.3、8.67、0.13、32.8、11....     

The determination of minor elements in steel by proton-induced prompt gamma-ray spectrometry

Pure elemental targets of Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo and W were irradiated with protons from 3.5 to 6.0 MeV, interference-free sensitivities were calculated for analysis by prompt gamma-ray spectrometry and sensitivity curves were plotted to show the variation of sensitivity with bombarding energy. Appropriate bombarding energies were selected for analysis and the extent of possible inter-element interferences and background effects were determined. Standard reference steels were used to evaluate this method for the determination of the minor elements Si, V, Cr, Mn and Co.     

玩具、铅笔中可溶性砷、锑、硒的形态分析

对玩具、铅笔中可溶性砷、锑、硒的形态分析方法进行了研究,对原子荧光光谱法测定不同价态砷、锑、硒的方法进行了优化,建立了砷、锑、硒的原子荧光光谱形态分析方法。该方法样品加标回收率为82.0%~110.0%,测定结果的相对标准偏差为1.35%~2.22%(n=10)。     

Determination of Geosmin and 2-Methylisoborneol in Water by Headspace Liquid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry

Geosmin (GSM) and 2-methylisoborneol (MIB) were extracted from water samples, adsorbed in organic solvent microdrop by headspace liquid-phase microextraction (HS-LPME), and were analyzed by gas chromatography-mass spectrometry (GC-MS). Influence factors such as the extraction solvent types, headspace and microdrop volumes, stirring rate, equilibrium and extraction time, and ionic strength for HS-LPME efficiency were thoroughly evaluated. Under optimized extraction and detection conditions, the calibration curves of GSM and MIB were linear in the range of 5–1000 ng/L. The detection limits of GSM and MIB were 1.1 and 1.0 ng/L, respectively. Average recoveries of 95.45–113.7% (n = 5) were obtained and method precisions were also satisfactory. Trace levels of the off-flavor compounds at ng/L in tap water and raw water were successfully quantified.     

电感耦合等离子体质谱法测定铁基体中稀土元素Nd和Dy

采用电感耦合等离子体质谱法测定铁基体中的稀土元素Nd和Dy,选择187Re作为内标以校正仪器的信号漂移,Nd和Dy元素的浓度与信号强度线性关系良好,相关系数(r2)分别为0.9998和0.9997,该方法测定Nd和Dy元素的检出限分别为0.02 ng/mL和0.006 ng/mL,平均回收率分别为99.5％和97.4％,测定结果的相对标准偏差分别为3.5％和4.3％.     

顶空-气相色谱-飞行时间质谱鉴定分析饮用水中的异味成分

使用顶空-气相色谱-飞行时间质谱结合差异化分析软件鉴定分析出了饮用水中的异味物质。质谱数据通过逐级筛查，降低化合物数量，通过T检验和倍数变化统计分析查找差异显著的化合物，利用结构解析确定异味成分为乙醛。通过正交试验优化了加热时间、加热温度、样品量和加盐量等因素。检出限和定量限分别为0.0033和0.010 mg/L，线性范围为0.010~0.500 mg/L，相关系数R²=0.997。对实际样品进行了检测，分析了产生异味的原因，并对相应的生产加工工艺提出了合理化建议。该方法简便、快速、灵敏，适用于鉴定分析饮用水中的异味成分。     

FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular geometry of biomolecule 5-aminouracil

FT-IR and FT-Raman spectra of the biomolecule 5-aminouracil were recorded in the regions 400–4000 cm⁻¹ and 10–3500 cm⁻¹, respectively. The observed vibrational wavenumbers were analyzed and assigned to different normal modes of vibration of the molecule. Density functional calculations were performed to support wavenumber assignments of the observed bands. A comparison with the molecule of uracil was made, and specific scale factors were employed in the predicted wavenumbers of 5-aminouracil. With the purpose of study the important molecule 5-aminouracil, its equilibrium geometry and harmonic wavenumbers were calculated for the first time by the B3LYP DFT method. The vibrational wavenumbers were compared with IR and Raman experimental data. Also good reproduction of the experimental wavenumbers is obtained and the % error is very small. All the tautomeric forms of 5-aminouracil were determined and optimized. The dimer forms were also simulated. The energy, atomic charges and dipole moments were discussed and several general conclusions were underlined.