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961.
Gloria C. Lin Maria L. Tsoukas Margaret S. Lee Salvador González Chitralada Vibhagool R. Rox Anderson Nikiforos Kollias 《Photochemistry and photobiology》1998,68(4):575-583
In an ideal world, photodynamic therapy (PDT) of abnormal tissue would reliably spare the surrounding normal tissue. Normal tissue responses set the limits for light and drug dosimetry. The threshold fluence for necrosis (TFN) was measured in normal skin following intravenous infusion with a photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA) Verteporfin as a function of drug dose (0.25-2.0 mg/kg), wavelength of irradiation (458 and 690 nm) and time interval (0–5h) between drug administration and irradiation. The BPD-MA levels were measured in plasma and skin tissue to elucidate the relationship between TFN, drug kinetics and biodistribution. The PDT response of normal skin was highly reproducible. The TFN for 458 and 690 nm wavelengths was nearly identical and the estimated quantum efficiency for skin response was equal at these two wavelengths. Skin phototoxicity, quantified in terms of 1/ TFN, closely correlated with the plasma pharmacokinetics rather than the tissue pharmacokinetics and was quadratically dependent on the plasma drug concentration regardless of the administered drug dose or time interval between drug and light exposure. This study strongly suggests that noninvasive measurements of the circulating drug level at the time of light treatment will be important for setting optimal light dosimetry for PDT with liposomal BPD-MA, a vascular photosensitizer. 相似文献
962.
963.
The reproducibility, the small scale as well as the large scale variability of137Cs extracted sequentially from the soil by using a modified Tessier procedure was investigated at several grassland sites in Bavaria/Germany and in the Chemobyl area. Because undisturbed grassland soils are never homogeneous with respect to their soil properties, all sequential extractions at the German sites were carried out at each plot separately for different soil layers (e.g., 0–2, 2–5, 5–10, 10–15, 15–20 and 20–30 cm). The results show that the coefficients of variation (CV) for the reproducibility of the extraction procedure for137Cs was (with some exceptions) around 10–20% for all fractions. For the small scale variability of137Cs (samples within an area of 10×10m2) the values for theCV were (again with a few exceptions) in the same range. Compared to that, the large scale variability of extractable137Cs (random soil samples within an area of 100×200 km2) was higher for all fractions, even though only moderately. The implications of these results with respect to a sampling design are discussed. 相似文献
964.
Summary The effect of extraction cell dimensions (i.d.: length) on supercritical fluid extraction (SFE) efficiencies of polychlorinated biphenyls (PCBs) is shown to be dependent on the type of sorbent used. For octadecylsilane (C18) sorbents, there is a significant increase in observed SFE recoveries of PCBs when the cell dimensions are made more broad (increased i.d.: length); whereas, no effect of cell geometry is observed when the common adsorbent, Florisil, is utilized. Additionally, recoveries decreased in proportion to the chlorine number, for the PCBs studied, for octadecylsilane sorbents, while no such effect was observed for Florisil. These results illustrate the magnitude of the matrix effect in SFE, which generally dominated observed recoveries, even in the simplest analyte/sorbent systems such as the one studied here. 相似文献
965.
The effect of pH on the dilution enthalpies of D-p-hydroxyphenylglycine in phosphate buffer solutions has been investigated by isothermal titration microcalorimetry at 298.15 K. The corresponding homogeneous enthalpic interaction coefficients have been calculated according to the excess enthalpy concept. The results show that the enthalpies of dilution of D-p-hydroxyphenylglycine in phosphate buffer solutions at different pH are all positive. The overall trend is that enthalpies of dilution become more positive with an increase of pH, but there is a minimum of the enthalpy of dilution at pH = 7.0. The enthalpic pair interaction coefficients, h
2, all have negative values. The results are interpreted from the point of view of solute-solute and solute-solvent interactions involved in the solvent effects. 相似文献
966.
在用溶胶-凝胶方法成功制备纳米TiO2、纳米CeO2包覆纳米TiO2材料的基础上,进行了氧敏性能、阻抗谱的测试和对比,并且通过热力学和活化能计算对实验结果进行了分析.实验结果表明:纳米CeO2包覆纳米TiO2材料的氧敏性能优于纯TiO2材料,.当包覆4.9mol?O2时材料的氧敏性能最好.热力学计算证明:CeO2对TiO2起到催化作用,从而改善TiO2的氧敏性能.对材料活化能计算表明:包覆纳米CeO2后材料的晶粒、晶界活化能显著降低,TiO2的活性得到提高:并且随着CeO2包覆量降低活化能降低,说明活化能存在极小值,CeO2包覆量有最优值,从而解释了实验结果中出现极值的现象. 相似文献
967.
IntroductionThepreparativeapproachofaneffectivebilTldslliccatalystisalwaysasubjectofboortantsignificanceinheterogeneouscatalysis.InourrecentstUdies,wefoundthatthebAnetallitcarbonylclustercoCo3(CO)12favorablygivesthebAnetalliccoCo3clusterontheSiOZsubdueaft… 相似文献
968.
八十年代以来,海洋天然有机化学仍然继续发展,大量新的化合物,尤其是具有生理活性的化合物不断出现,海洋天然物的生物合成和人工合成研究也有新的进展。在海洋生物中,研究得最多的是海藻和海绵,其次便是珊瑚。 相似文献
969.
A series of phenyl modified polydimethylsiloxane (PDMS) / polyhydrogenmethylsiloxane (PHMS) random copolymers containing both internal Si‐H and terminal SiH2 and T (MeSiO3/2) units was synthesized in one step through n‐BuLi‐catalyzed ring‐opening polymerization of cyclic comonomers and characterized by GPC, IR and 1H and 29Si NMR. Sequential microstructures of these copolymers were determined by 29Si‐NMR spectroscopy. Epoxy‐modified polysiloxanes were prepared and used as comparable standards for the assignment of the NMR spectra. A hydride‐transfer mechanism has been proposed to account for the formation of terminal Si‐H and T group. Detailed sequential analyses and chemical shifts of 29Si‐NMR for various siloxane units are reported for the first time. 相似文献
970.
Zhan‐Xin Zhang Wei‐Dong Xie Ping‐Lin Li Yan‐Ping Shi Zhong‐Jian Jia 《Helvetica chimica acta》2006,89(12):2927-2933
Six new compounds were isolated from the whole plant of Sonchus uliginosus, including three eudesmane‐type sesquiterpenoids (1β,6α)‐1,6,14‐trihydroxyeudesm‐3‐en‐12‐oic acid γ‐lactone ( 1 ), (1β,6α)‐1,6,14‐trihydroxyeudesma‐3,11(13)‐dien‐12‐oic acid γ‐lactone ( 2 ), and (1β,6α)‐1,6‐dihydroxy‐14‐O‐[(4‐hydroxyphenyl)acetyl]eudesma‐3,11(13)‐dien‐12‐oic acid γ‐lactone ( 3 ), and three phenylpropane derivatives, 4‐hydroxy‐γ,3,5‐trimethoxybenzenepropanol ( 6 ), γ,3,4,5‐tetramethoxybenzenepropanol ( 7 ), and γ,3,4,5‐tetramethoxybenzenepropanol acetate ( 8 ), together with the two known compounds 4 and 5 . The new structures were elucidated by means of spectroscopic methods, such as IR, EI‐MS, HR‐ESI‐MS, 1D‐ and 2D‐NMR, and by comparison of the spectroscopic data with those reported for structurally related compounds. 相似文献