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121.
基于光波在宇称-时间(PT)对称波导中传输的理论模型, 数值研究了亮孤子在呈高斯分布的PT对称克尔非线性平板波导中的传输和控制. PT对称波导, 要求波导的折射率分布呈偶对称, 而增益/损耗分布呈奇对称. 结果表明: 当波导的折射率分布强度为正时, PT对称波导的中心折射率最大, 即使没有自聚焦克尔非线性效应, PT对称波导也可以束缚光波, 形成波浪形光束且长距离传输; 当折射率分布强度为负时, PT对称波导的中心折射率最小, 光波的传输方向发生偏移. 而增益/损耗分布可控制光波的偏移方向: 增益/损耗分布强度为正, 光波向左偏移; 强度为负, 光波向右偏移; 强度为零时, 光波被分为两束. 且当折射率分布强度为负时, 可以很好地抑制相邻亮孤子间的相互作用. 该研究结果可为未来PT对称波导在全光控制方面的应用提供一定的理论依据. 相似文献
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A new method of ionic liquids based cycle flow single drop microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) was proposed for the determination of trace Co, Hg and Pb with 1-(2-pyridylazo)-2-naphthol (PAN) as both extractant and chemical modifier and 1-butyl-3-methylimidazolium hexafluorophosphate as the extraction solvent. Several factors that influence the microextraction efficiency, such as sample pH, sample flow rate, microdrop volume and extraction time, were investigated and the optimized microextraction conditions were established. Co, Hg and Pb in the post-extraction ionic liquids phase were directly determined by ETV-ICP-MS with the use of PAN as chemical modifier. The chemical modification of PAN in ETV-ICP-MS was studied and the factors affecting the vaporization behaviors of target analytes were investigated. Under the optimized conditions, the detection limits of the method were 1.5, 9.8 and 6.7 pg/mL for Co, Hg and Pb, with the relative standard deviations for 0.5 ng/mL (n = 7) of Co, Hg and Pb were 7.7%, 5.2% and 12.0%, respectively. After 10 min of extraction, the enrichment factors were 350 (Co), 50 (Hg) and 60 (Pb). The proposed method was successfully applied to the determination of trace Co, Hg and Pb in human serum and environmental water samples. In order to validate the developed method, a certified reference material of human hair (GBW07601) was analyzed and the determined values were in good agreement with the certified values. 相似文献
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Guan SH Xia JM Lu ZQ Chen GT Jiang BH Liu X Guo DA 《Magnetic resonance in chemistry : MRC》2008,46(2):186-190
Three new lignan glycosides (1-3) were isolated from the stems of Akebia trifoliata. Their structures were elucidated as (7R,8R,7'R,8'R)3,3',5,5'tetramethoxy-4,4'dihydroxy-7,9':7',9-diepoxylignan-4-O-beta-D-glucopyranoside (1), (7S,8S,8'R)-4,4',9-trihydroxy-3,3',5,5'-tetramethoxy-7,9'-epoxylignan-7'-one 9-O-beta-D-glucopyranoside (2), (7R,8R,8'S)-4,4',9-trihydroxy3,3',5,5'-tetramethoxy-7,9'-epoxylignan-7'-one 9-O-beta-D-glucopyranoside (3) by spectral analyses, primarily NMR, MS and CD. The NMR assignments for the compounds were carried out using 1H, 13C, DEPT, COSY, HSQC, HMBC and ROESY NMR experiments. 相似文献
128.
对PPh2py配合物[M(CO)3(PPh2py)2](M=Fe, Ru)的三种构型的异构体1-6进行了研究. 其中PPh2py以两个P原子与M配位形成HH构型1(Fe)和4(Ru), 以一个P和一个N原子与M配位形成HT构型2(Fe)和5(Ru), 以两个N原子与M配位形成HH’构型3(Fe)和6(Ru). 结果表明, (1) PPh2py中P原子对HOMO轨道的贡献最大, PPh2py作为电子给体时易以P原子与金属原子结合. (2)从分子能量和相互作用能数据表明, 配合物中HH构型最稳定, HH'构型最不稳定, 这与合成产物为HH构型的结果一致. (3) 键长和Wiberg键级均表明P—M键比N—M键结合力强. P、M原子间存在σ键, 而N、Fe原子间仅存在nN→n*M或nN→σ*M-P的电荷转移作用. (4) HH构型中M对HOMO的贡献最大, PPh2py向M的电荷转移最强, 使M的负电荷最大, 故HH构型最易作为电子给体以M原子与第二个金属配位形成双核配合物. 相似文献
129.
Yong Tao Jing-Fu Liu Xia-Lin Hu Hong-Cheng Li Thanh Wang Gui-Bin Jiang 《Journal of chromatography. A》2009,1216(35):6259-6266
By using ionic liquid as membrane liquid and tri-n-octylphosphine oxide (TOPO) as additive, hollow fiber supported liquid phase microextraction (HF-LPME) was developed for the determination of five sulfonamides in environmental water samples by high-performance liquid chromatography with ultraviolet detection The extraction solvent and the parameters affecting the extraction enrichment factor such as the type and amount of carrier, pH and volume ratio of donor phase and acceptor phase, extraction time, salt-out effect and matrix effect were optimized. Under the optimal extraction conditions (organic liquid membrane phase: [C8MIM][PF6] with 14% TOPO (w/v); donor phase: 4 mL, pH 4.5 KH2PO4 with 2 M Na2SO4; acceptor phase: 25 μL, pH 13 NaOH; extraction time: 8 h), low detection limits (0.1–0.4 μg/L, RSD ≤ 5%) and good linear range (1–2000 ng/mL, R2 ≥ 0.999) were obtained for all the analytes. The presence of humic acid (0–25 mg/L dissolved organic carbon) and bovine serum albumin (0–100 μg/mL) had no significant effect on the extraction efficiency. Good spike recoveries over the range of 82.2–103.2% were obtained when applying the proposed method on five real environmental water samples. These results indicated that this present method was very sensitive and reliable with good repeatabilities and excellent clean-up in water samples. The proposed method confirmed hollow fiber supported ionic liquid membrane based LPME to be robust to monitoring trace levels of sulfadiazine, sulfamerazine, sulfamethazine, sulfadimethoxine and sulfamethoxazole in aqueous samples. 相似文献
130.
Li WY Chen XF Xuan CS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):1769-1775
A spectrofluorimetric method was discussed for the determination of three antibacterial quinolone derivatives, ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CIP) through charge-transfer complexation (CTC) with 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, TBBQ). The method was based on the reaction of these drugs as n-electron donors with the pi-acceptor TBBQ. TBBQ was found to react with these drugs to produce a kind of yellow complexes and the fluorescence intensities of the complexes were enhanced by 29-36 times more than those of the corresponding monomers. UV-vis, (1)H NMR and XPS techniques were used to study the complexes formed. The various experimental parameters affecting the fluorescence intensity were studied and optimized. Under optimal reaction conditions, the rectilinear calibration graphs were obtained in the concentration range of 0.021-2.42 microg mL(-1), 0.017-2.63 microg mL(-1) and 0.019-2.14 microg mL(-1) for OFL, NOR and CIP, respectively. The methods developed were applied successfully to the determination of the subject drugs in their pharmaceutical dosage forms with good precision and accuracy compared to official and reported methods as revealed by t- and F-tests. 相似文献