尼群地平晶型转变条件及其影响因素的确定

根据熔化数据推算相变稳定性理论计算了尼群地平不同晶型之间的相变温度, 并分别考察了高温、高温和高湿及高压条件下的晶型转变. 理论推导尼群地平I与II, 尼群地平I与III, 尼群地平II与III的转化温度分别为158.88, 160.50和158.65 ℃, 三者均为单变关系, 且在高温条件下尼群地平II, III都转变为尼群地平I, 在高压条件下, II易转变为I. 试验结果表明室温下尼群地平I为稳定型, II和III为亚稳定型, 3种晶型稳定性顺序为尼群地平I＞II＞III.     

固相微萃取/气相色谱-质谱联用技术测定燕窝中挥发性成分

该文以印尼产的燕窝为材料,使用固相微萃取(SPME)技术萃取燕窝中挥发性成分并以气相色谱-质谱(GC-MS)联用仪进行测定。考察了萃取头类型、萃取温度、萃取时间和解吸时间对固相微萃取(SPME)在燕窝挥发性成分测定中的影响。结果表明:以65μm聚二甲基硅氧烷/二乙烯基苯(PDMS/DVB)萃取头、在60℃下萃取60 min,解吸2 min的条件下,SPME/GC-MS技术可检出燕窝中挥发性成分醇、烃、醛、酯、醚类等化合物共82种。该方法具有操作简便、快速、重复性好和灵敏度高的特点,适用于燕窝中挥发性成分的测定。     

同时蒸馏萃取-气相色谱/质谱法分析烟草中挥发性成分

本文对云南12种烟叶中挥发性成分进行提取分离,气相色谱/质谱测定.系统地对同时蒸馏萃取条件和色谱分离条件进行优化,结合谱库检索和匹配度定性方法鉴定149种化合物,并对其中的35种重要香气成分进行了定量分析,包括酮类7种、醇类6种、烯烃类4种、烟碱类3种、烷烃类2种、醛类2种、酯类2种、呋喃类2种等.该方法具有81.09％～97.45％的高回收率.结果表明,同时蒸馏萃取集采样、萃取、浓缩于一体,操作简单快速,适合于烟草中挥发性成分的提取,结合气相色谱/质谱联用仪(GC-MS)分离测定,能准确对挥发性成分进行定性和定量分析.     

山核桃外蒲壳无机成分的分析研究

采用原子吸收分光光度法(AAS)对山核桃外蒲壳的无机成分进行分析. 结果表明, 山核桃外蒲壳中含有较高的K、Ca以及Fe、Mn、Zn、Mg、Cu等微量元素. 通过单因素试验, 得出最佳湿消化法条件为: 氧化性混酸V(HNO3)∶V(HClO4)＝4∶1、体积75 mL、消解时间36 h、加热温度180 ℃;最佳干消化法条件为: 灰化温度600 ℃, 煅烧时间5.5 h.     

微囊藻毒素-LR阻抗型电化学免疫传感器的研究

基于1,6-己二硫醇自组装技术和纳米金吸附作用相结合的方法固定微囊藻毒素抗体,采用循环伏安法及交流阻抗法研究了该修饰电极的电化学性质,并优化了微囊藻毒素-LR(MC-LR)的测定条件.结果表明,在优化条件下,阻抗变化值与MC-LR标准品质量浓度分别在0.25 ～2.0 μg/L和2.0 ～95 μg/L 范围内呈良好的线性关系,其线性相关系数分别为0.994 4和0.997 2,检出限达0.085 μg/L(S/N=3);电极的重现性及稳定性较好,连续测定12次,相对标准偏差为7.8%;4 ℃下储存60 d后阻抗响应信号无明显变化;应用于饮用水中MC-LR的测定,样品的回收率为93% ～118%;检测时间为15 min.该传感器无需标记、灵敏度高、稳定性好,可用于快速检测饮用水源水中的MC-LR.     

预辐照接枝丙烯酸、苯乙烯磺酸钠对聚全氟乙丙烯膜性能的影响

采用常温下γ射线预辐照引发接枝的方法,在聚全氟乙丙烯(FEP)上接枝了丙烯酸(AA)和对苯乙烯磺酸钠(SSS),制备了一种含羧酸基团和磺酸基团的接枝膜.傅立叶变换红外光谱(FT-IR)分析证明了磺酸基团和羧酸基团的成功引入.采用XRD、TGA和接触角研究了接枝率对FEP膜的结晶度、热学特性及亲水性等性能的影响.结果表明,随着制备的FEP膜接枝率的增加,膜的结晶度、热稳定性和接触角逐渐减小;与此相反,FEP膜的亲水性能随接枝率的增加而增加.接枝膜湿敏性能测定结果表明,在相对湿度从5%RH变化到98%RH时,接枝膜电阻线性变化范围接近3个数量级,具有响应速度快(吸附<1min,解吸<2min),湿滞小(<3%RH)的特点,具有应用于电阻型湿度传感器的广阔前景.     

顶空液液萃取-气相色谱-质谱法用于白术挥发性成分的分析

采用高温顶空液相萃取再转移的方法,对中药白术中挥发性成分进行萃取分离富集,采用顶空液液萃取/气相色谱-质谱(HS-LP-LPE/GC-MS)联用法进行测定,并与传统水蒸汽蒸馏法(SD)提取的挥发性成分进行对比。对各种测定条件和影响因素进行了考察,最佳萃取条件为:1.0 mL PEG 400为高温萃取剂,样品用量1.2 g,萃取温度120℃,萃取时间60 min,再将萃取剂用1.0 mL正己烷进行反萃取后进行GC-MS分析;采用HS-LP-LPE/GC-MS鉴定了33个组分,占总组分含量93.18%;SD鉴定了31个组分,占总组分含量97.12%。两种方法共同检测到的组分有29个,均以苍术酮(Atractylone)含量最高。结果表明,两种方法所提取的组分基本相同,可用于白术挥发性成分的测定。     

分子筛型声学增强材料的储存耐候性能

研究了湿度和有机物小分子等储存耐候条件对声学增强材料谐振频率偏移值的影响,探讨了由不同硅铝比分子筛组成的声学增强材料在不同湿度及有机物小分子气氛中储存后的谐振频率及偏移值的变化规律.研究结果表明,由既定硅铝比分子筛组成的声学增强材料在25℃/50%相对湿度(RH)和25℃/95%RH条件下储存后,其谐振频率偏移值未发生明显变化.氮气吸附实验结果表明, 25℃下氮气分子占据了较少的比表面积,水分子的存在不影响声学增强材料对氮气分子的吸附.在25℃/50%RH条件下放置后,声学增强材料在25℃/95%RH条件下吸附的水分子会逐渐脱附.声学增强材料在不同种类有机物小分子气氛中储存后,其谐振频率偏移值呈不同的变化趋势.对于尺寸较小的有机物小分子,由于存在可逆吸附,声学增强材料的谐振频率偏移值未有明显变化;对于尺寸较大或具有小尺寸端基基团的有机物小分子,由于存在嵌入式吸附,声学增强材料的谐振频率偏移值明显降低.     

羰基和砜基共交联磺化聚酰亚胺质子交换膜的制备及燃料电池性能

为提高磺化聚酰亚胺质子交换膜(SPI PEM)的高温耐水解稳定性及电池性能,用3,5-双(4-氨基苯氧基)苯甲酸(BAPBa)制备了一系列六元环型SPI PEM,利用甲磺酸/五氧化二磷溶液(PPMA)制备了羰基和砜基共交联的SPI PEM.测定了SPI PEM的质子传导率、耐水解稳定性、机械性能及电池性能.结果表明,羰基和砜基共交联提高膜交联度的同时减少了磺酸基的消耗,使SPI PEM保持较高的质子传导率.在相对湿度为50%RH时,羰基和砜基共交联SPI PEM的质子传导率为7.8 m S/cm,比同样条件下砜基交联的SPI PEM提高28%.羰基和砜基共交联的SPI PEM在130℃水中老化500 h后断裂伸长率为18%,质子传导率未明显降低.羰基和砜基共交联SPI PEM作为电池时,最大功率密度达到0.85 W/cm2,是砜基交联PEM的1.3倍.     

石墨炉-原子吸收光谱法测定含维生素B_(12)制品中铅量

提出了用石墨炉-原子吸收光谱法测定维生素B_(12)制品(例如含维生素B_(12)的保健食品及饲料等)中铅的含量。样品于压力罐中用硝酸及过氧化氢经在60℃～160℃范围内阶梯升温消解,所得溶液蒸缩至0.5mL后,加水定容至10mL,按选定的仪器工作条件测定其中铅量。采用热解涂层平台石墨管。用阶梯升温方式先后于350℃(5s)和550℃(2 s)进行灰化,并选择在1700℃进行原子化。方法的检出限(3S/N)为0.1ng。在20.0μg·L~(-1)浓度水平上重复测定8次做回收及精密度试验,测得平均回收率为100.2%,相对标准偏差为0.39%。     

Core Cross‐Linked Micelle‐Based Nanoreactors for Efficient Photocatalysis

Stable nanoscale cross‐linked polymer micelles containing Ru complexes (Ru‐CMs) were prepared from monomethoxy[poly(ethylene glycol)]‐block‐poly(L ‐lysine) (MPEG‐PLys) and [(bpy)₂Ru(fmbpy)](PF₆)₂ (bpy=bipyridine, fmbpy=5‐formy‐5′‐methyl‐2,2′‐bipyridine). To stabilize the micelles, bifunctional glutaraldehyde was used as a cross‐linker to react with the free amino groups of the PLys block. After that, the Ru‐CMs showed very good stability in common solvents. The Ru‐CMs showed photocatalytic activity and selectivity in the oxidation of sulfides that were as high as those of the well‐known [Ru(bpy)₃(PF₆)₂] complex, because the micelles were swollen in the methanol–sulfide mixture. Moreover, because of the nanoscale size of the particles and their high stability, the Ru‐CM photocatalysts can be readily recovered by ultrafiltration and reused without loss of photocatalytic activity. This work highlights the potential of using cross‐linked micelles as a platform for developing highly efficient heterogeneous photocatalysts for a number of important organic transformations.     

Highly sensitive and ultrafast response surface acoustic wave humidity sensor based on electrospun polyaniline/poly(vinyl butyral) nanofibers

Polyaniline (PANi) composite nanofibers were deposited on surface acoustic wave (SAW) resonator with a central frequency of 433 MHz to construct humidity sensors. Electrospun nanofibers of poly(methyl methacrylate), poly(vinyl pyrrolidone), poly(ethylene oxide), poly(vinylidene fluoride), poly(vinyl butyral) (PVB) were characterized by scanning electron microscopy, and humidity response of corresponding SAW humidity sensors were investigated. The results indicated that PVB was suitable as a matrix to form nanofibers with PANi by electrospinning (ES). Electrospun PANi/PVB nanofibers exhibited a core–sheath structure as revealed by transmittance electron microscopy. Effects of ES collection time on humidity response of SAW sensor based on PANi/PVB nanofibers were examined at room temperature. The composite nanofiber sensor exhibited very high sensitivity of ∼75 kHz/%RH from 20 to 90%RH, ultrafast response (1 s and 2 s for humidification and desiccation, respectively) and good sensing linearity. Furthermore, the sensor could detect humidity as low as 0.5%RH, suggesting its potentials for low humidity detection. Attempts were done to explain the attractive humidity sensing performance of the sensor by considering conductivity, hydrophilicity, viscoelasticity and morphology of the polymer composite nanofibers.     

Tradition- and science-based quality control of Chinese medicines--introducing the Phyto-True system

The current QC practice of quantifying presumed active chemicals or arbitrarily selected chemical markers is of doubtful value in assessing multicomponent complex traditional Chinese medicines (CMs) and often leads to an inconsistent or irreproducible research and clinical outcome. Consequently, the first and most important step in the QC of CMs (or other botanical medicines) whose exact active chemical components are unknown is to use analytical techniques that can comprehensively define the totality of the components/attributes making up their identity and quality. One of the most versatile techniques is HPTLC. Using HPTLC, along with other simple techniques such as FTIR spectroscopy and UV-Vis spectroscopy combined with complementary gene expression profiling, we have been able to correctly identify CM materials, detect adulterants, and differentiate closely related materials and botanical species. Our research has resulted in the introduction of the concept and specimens of Phyto-True Reference Material (PTRM), aka Representative Botanical Reference/Research Material (RBRM), now commercially available, and a novel patent-pending technology (Phyto-True system) that can serve as a starting point for the meaningful QC of traditional CMs so far not possible for these complex materials. Examples will be highlighted to demonstrate this new concept.     

Exploring fiber optic approach to sense humid environment over nano-crystalline zinc oxide film

A novel humidity sensor made up of nano-crystalline zinc oxide (ZnO) film, coated onto the U-shaped typical glass substrate as a wave guide, conjugated with an optical fiber and He-Ne un-polarized laser source. The nano-crystalline zinc oxide (ZnO) was synthesized using single molecular precursor method. The resulting material was characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), thermogravimetric-differential thermal analysis (TG-DTA) and scanning electron microscopy (SEM). In the thin film, ZnO particles exhibited the wurtzite phase structure with the particle size in a diameter range of 70-80 nm. The humidity sensing characteristic has been estimated by measuring the optical permeability (OP) as a function of percentage relative humidity (%RH) in the ranging from 5 to 90 inside a closed chamber. The OP decreases linearly with increase in %RH with a respond time of about 30 and recovery time of 35 s. The sensor exhibits the sensitivity of 0.45 in the %RH range 5-50 and 0.30 from 50 to 90.     

联合载体用于改善白藜芦醇固体分散体性能

通过载体聚乙烯吡咯烷酮(PVPk29/32)和羟丙基甲基纤维素(HPMC),采用溶剂法制备白藜芦醇(Res)二元及三元固体分散体。 用傅里叶变换红外光谱(FTIR)、调制式差示扫描量热(MDSC)和X射线粉末衍射(XRD)等技术手段来表征Res二元和三元固体分散体并考察其溶出度。 FTIR结果显示,Res与PVPk29/32及HPMC均存在氢键相互作用;溶出结果表明,二元和三元固体分散体均能提高药物的溶出度。 而XRD和MDSC结果表明,三元固体分散体的相容性优于二元固体分散体;3个月的加速实验(40 ℃,75%RH(relative humidity))中,XRD、MDSC及体外溶出结果表明,Res三元固体分散体的稳定性优于Res二元固体分散体。 HPMC的加入可以改善Res三元固体分散体的溶出及稳定性。     

预辐射接枝四氟乙烯-乙烯共聚物湿敏膜的制备及特性研究

利用2 MeV电子加速器, 在常温下采用预辐照引发接枝的方法, 在四氟乙烯-乙烯共聚物(ETFE)上接枝丙烯酸(AA)和对苯乙烯磺酸钠(SSS), 制备了一种含羧酸基团和磺酸基团的接枝膜. 傅里叶变换红外光谱(FTIR)分析结果证明了磺酸基团和羧酸基团的成功引入, 并对接枝膜的热力学和化学特性进行了研究. 结果表明, 随着接枝率的增加, 接枝膜的结晶度逐渐降低, 接触角逐渐减小, 接枝膜的亲水性逐渐增强. 利用制备的接枝膜构建了电阻型湿度传感器, 并测定了传感器的电学特性. 在相对湿度(RH)从5%变化到98%时, 传感器电阻线性变化范围接近4个数量级, 具有响应速度快(吸附<1 min, 解吸<2 min), 湿滞小(<2%RH)的特点.     

Ultra-thin CoAl layered double hydroxide nanosheets for the construction of highly sensitive and selective QCM humidity sensor

To achieve real-time monitoring of humidity in various applications, we prepared facile and ultra-thin CoAl layered double hydroxide (CoAl LDH) nanosheets to engineer quartz crystal microbalances (QCM). The characteristics of CoAl LDH were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectric spectroscopy (XPS), Brunauer–Emmett–Telle (BET), atomic force microscopy (AFM) and zeta potential. Due to their large specific surface area and abundant hydroxyl groups, CoAl LDH nanosheets exhibit good humidity sensing performance. In a range of 11.3% and 97.6% relative humidity (RH), the sensor behaved an ultrahigh sensitivity (127.8 Hz/%RH), fast response (9.1 s) and recovery time (3.1 s), low hysteresis (3.1%RH), good linearity (R² = 0.9993), stability and selectivity. Besides, the sensor can recover the initial response frequency after being wetted by deionized water, revealing superior self-recovery ability under high humidity. Based on in-situ Fourier transform infrared spectroscopy (FT-IR), the adsorption mechanism of CoAl LDH toward water molecules was explored. The QCM sensor can distinguish different respiratory states of people and wetting degree of fingers, as well as monitor the humidity in vegetable packaging, suggesting excellent properties and a promising application in humidity sensing.     

以硅藻土为硅源合成NaA分子筛及其质子传导性能研究

以硅藻土为硅源, 在Na₂O-Al₂O₃-SiO₂(硅藻土)-H₂O体系中, 采用水浴加热搅拌的方法在较低温度下快速合成了LTA型硅铝分子筛NaA. 通过调节温度和反应物的活性, 优化了NaA分子筛的合成过程, 实现了其在较短时间、 较低温度下的快速合成. 所合成的NaA分子筛展现出良好的质子传导性能, 在室温和100%相对湿度条件下, 其质子传导率为1.72×10^-3 S/cm, 且随着温度的升高其质子传导率逐渐增大, 在80 ℃和100%相对湿度条件下, 质子传导率可以达到5.96×10^-3 S/cm.     

Influence of angiography contrast media on viability of endotherial cells in cultures

We investigated the influence of angiography contrast media (CMs) on viability of bovine endothelial cells in culture. Six CMs used were iothalamate (IOT; Conray^® 400) of ionic monomer, ioxaglate (IOX; Hexabrix^® 320) of ionic dimer and iomeprol (IOM; Iomeron^® 300) of non-ionic monomer, and diatrizoate (DIA; Urografin^® 76%) of ionic monomer, iopamidol (IOP; Iopamiron^® 300) and iohexol (IOH; Omnipaque^® 300) of two non-ionic monomers. Endothelial cells, harvested from bovine aortae, were cultivated in MEM for the former three CMs of IOT, IOX and IOM, and in RPMI for the latter three CMs of DIA, IOP and IOH at 37 °C with 5% CO₂ at 100% humidity. Survival endotherial cells for the CMs were statistically compared with those for a physiological saline (SAL) at 0.9% NaCl (control) versus the volume and iodine concentrations of CMs, in which all the data were reproduced well by the reverse-S-shaped logistic curves and were also represented by a single master curve of the logistic equation with the non-dimension variables. In MEM, the effects to the endothelium were more adverse in the order of IOT>IOX>IOM, and in RPMI DIA>IOHIOP, i.e. the critical concentration of CM was the least for ionic monomers worse than all, moderate for ionic dimer and the greatest for non-ionic monomers.     

Cyclic voltammetry modeling, geometries, and electronic properties for metallofullerene complexes with mu3-eta2:eta2:eta2-C60 bonding mode

Reduction potential (E(red)) values have been calculated and compared with available cyclic voltammetry (CV) data for 10 metallofullerene complexes with the mu(3)-eta(2):eta(2):eta(2)-C(60) (M(3)-C(6)[C(60)]) bonding mode. Consideration of bulk solvent effects is essential for the calculation of the E(red) values. Scaling factors for the electrostatic terms of the solvation energies have been introduced to fully describe the experimental cyclic voltammograms with a small mean deviation of 0.07 V. Multiple electron reductions induce movement of the metal cluster moieties on the C(60) surface, which is accompanied with the changes in some M-C[C(60)] bonds from pi-type to sigma-type mode. However, the changes in M(3)-C(60) distances, as well as the geometric changes of M(3) and C(60), are small for the reductions, which is in harmony with the high chemical and electrochemical stability of the metallofullerenes. Our population analyses reveal that the added electrons are not localized at the C(60) moieties, and electron population in the metal clusters is significant, more than 20% (av. 37%), for all the reductions. Furthermore, we demonstrated that the two close one-electron redox waves in CV diagrams are strongly correlated with significant electron delocalization, about 40-80%, to the metal-cluster moieties in these metallofullerene complexes.