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51.
52.
反相高效液相色谱法制备银杏叶中聚戊烯醇同系物单体 总被引:1,自引:0,他引:1
利用制备高效液相色谱法从银杏叶中分离制备了聚戊烯醇同系物单体。在HiQ sil C18柱上,以异丙醇-甲醇-正己烷-水(体积比为50∶25∶15∶4)为流动相,流速10 mL/min,采用等度洗脱方式,制备了8种化合物,经紫外光谱、红外光谱及质谱分析,确认它们分别为C70,C75,C80,C85,C90,C95,C100和C105聚戊烯醇,其中主要成分为C85及C90聚戊烯醇。高效液相色谱分析表明,制备的C75C105聚戊烯醇化合物的纯度均在96%(质量分数)以上。在该色谱条件下,各色谱峰达到了基线分离, 相似文献
53.
Hairui Liu Zheng Lou Hui Wang Jungang Miao 《Journal of Infrared, Millimeter and Terahertz Waves》2009,30(4):401-409
A method of designing high performance millimeter wave quasi-optical Faraday rotators (QOFR) is reported in this paper. First,
the dielectric and magnetic parameters for the ferrite sample are determined by fitting theoretical curves to the measured
data. These fitted parameters are then used in a precise numerical model to predict the rotation angle and insertion loss
of the QOFR. Finally, the parameters of the QOFR are optimized according to the requirements of devices. Examples are given
showing the performance of the QOFR with an isolation better than 20 dB and an insertion loss less than 0.6 dB from 75 GHz
to 95 GHz. 相似文献
54.
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The anti-friction and wear-resistant performances of bonded MoS2 solid lubricating films filled with nano-LaF3 filler were investigated under in drying wear conditions, the corrosion-resistant performances of bonded lubricating films was evaluated according to ASTM-B117, and the characteristics of the bonded lubricating films were examined by TEM and elemental x-ray map. The wear-resistant performance of the bonded lubricating films filled with nano-LaF3 filler increases with increasing content of nano-LaF3 filler within a content range between 0 and 5 wt%, whereas the bonded lubricating films filled with 0.5–1 wt% micro-LaF3 filler exhibit the better wear-resistant performances. The incorporation of both nano-LaF3 and micro-LaF3 filler leads the increase of the coefficient of friction of the bonded lubricating films. The LaF3 filler can improve the corrosion-resistant performance of the bonded MoS2 solid lubricating films, whereas the incorporation of nano-LaF3 filler is more effective to improve the corrosion-resistant performance of the bonded lubricating films than micro-LaF3 filler. The improvement in the wear-resistant and corrosion-resistant performances of the bonded lubricating films by the incorporation of the nano-LaF3 filler is attributed to the strengthened interfacial bonding among the nano-LaF3 and the MoS2 lubricant and the polymeric matrix. However, a too high mass fraction of the nano-LaF3 filler in the bonded lubricating films will increase surface and interface defects, and lead the worsening of corrosion-resistant performance of the bonded lubricating films. 相似文献
56.
Hyojin Lee Chi P. Huynh Stephen C. Hawkins Mustafa Musameh Dae Hyung Kim 《Liquid crystals》2013,40(3):322-327
We investigated the orientational and electro-optical properties of a nematic liquid crystal (LC) aligned with a directly spinnable carbon nanotube (CNT) web functioning both as an electrode and as an alignment layer. The LC molecules were uniformly oriented along the drawing direction of the CNT web and the spatially averaged birefringence was comparable to a rubbed polyimide sample. The CNT web sample also showed smaller residual DC and hysteresis compared to the polyimide sample. 相似文献
57.
Wan K. Jo Jong H. Lee 《International journal of environmental analytical chemistry》2013,93(15):1412-1424
A lesser degree of information is available with respect to microenvironments associated with potential exposure to naphthalene, in comparison with other volatile organic compounds. The current study investigated the levels of benzene as well as naphthalene, both in the indoor and outdoor air of apartments and in the cabins of passenger cars. Two groups of 20 apartment buildings (20 new and 20 old) were chosen on the basis of the selection criteria (apartment location and size). In addition, 10 actual commuters were recruited for this study. The equal number of drivers was recruited for the study for comparison of two types of fuels for vehicles (five drivers of gasoline-fuelled and five drivers of diesel-fuelled passenger cars). Indoor naphthalene concentrations were similar between old and new apartments, while the benzene concentrations in new apartments were significantly higher than those of old apartments. The naphthalene concentrations in bedrooms, where wardrobes with moth repellent (MRs) were placed, were significantly higher than those for living rooms where no MRs were present. In turn, these indoor concentrations were significantly higher than outdoor levels. It is noteworthy that the mean and median values of naphthalene measured in the bedrooms exceeded the USEPA RfC (inhalation reference concentration) of 3?µg?m?3, and the living room values were close to the RfC, while the residential benzene levels exceeded the European benzene limit of 5?µg?m?3. In contrast, the maximum outdoor levels were well below that of the RfC. The use of passenger cars appeared to be a significant daily activity for both naphthalene and benzene exposure. The naphthalene-to-benzene ratios varied with the type of microenvironments. Both the indoor naphthalene and benzene concentrations in the present study were much higher than those of other studies. 相似文献
58.
Nasrin Sabet Sarvestany Abdulali Farzad Massoud Mir 《Journal of Dispersion Science and Technology》2014,35(12):1745-1750
Although the compression ignition engines are a significant source of power, their detrimental emissions create considerable problems to the environment as well as to humans. The objective of the present experimental investigation is to examine the effects of the magnetic nanofluid fuels on combustion performance characteristics and exhaust emissions. In this regard, the Fe3O4 nanoparticles dispersed in the diesel fuel with the nanoparticle concentrations of 0.4 and 0.8 vol% were employed for combustion in a single-cylinder, direct-injection diesel engine. After a series of experiments, it was demonstrated that the nanoparticle additives, even at very low concentrations, have considerable influence in diesel engine characteristics. Furthermore, the results indicated that the nanofluid fuel with nanoparticle concentration of 0.4 vol% shows better combustion characteristics in comparison with that of 0.8 vol%. Based on the experimental results, NO x and SO2 emissions dramatically reduce, while CO emissions and smoke opacity noticeably increase with increasing the dosing level of nanoparticles. 相似文献
59.
Rapid quantitative analysis of individual anthocyanin content based on high‐performance liquid chromatography with diode array detection with the pH differential method 下载免费PDF全文
Huayin Wang 《Journal of separation science》2014,37(18):2535-2544
A new quantitative technique for the simultaneous quantification of the individual anthocyanins based on the pH differential method and high‐performance liquid chromatography with diode array detection is proposed in this paper. The six individual anthocyanins (cyanidin 3‐glucoside, cyanidin 3‐rutinoside, petunidin 3‐glucoside, petunidin 3‐rutinoside, and malvidin 3‐rutinoside) from mulberry (Morus rubra) and Liriope platyphylla were used for demonstration and validation. The elution of anthocyanins was performed using a C18 column with stepwise gradient elution and individual anthocyanins were identified by high‐performance liquid chromatography with tandem mass spectrometry. Based on the pH differential method, the high‐performance liquid chromatography peak areas of maximum and reference absorption wavelengths of anthocyanin extracts were conducted to quantify individual anthocyanins. The calibration curves for these anthocyanins were linear within the range of 10–5500 mg/L. The correlation coefficients (r2) all exceeded 0.9972, and the limits of detection were in the range of 1–4 mg/L at a signal‐to‐noise ratio ≥5 for these anthocyanins. The proposed quantitative analysis was reproducible with good accuracy of all individual anthocyanins ranging from 96.3 to 104.2% and relative recoveries were in the range 98.4–103.2%. The proposed technique is performed without anthocyanin standards and is a simple, rapid, accurate, and economical method to determine individual anthocyanin contents. 相似文献
60.