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21.
实验检测了波长为245nm的紫外光激发乙醚-水溶液的荧光光谱。在二阶导数分析的基础上,对乙醚-水溶液的荧光光谱作高斯分解,获得了7条高斯谱线并测定了各自的的中心波长、谱峰强度和半峰宽度。利用高斯基元参数进行了多峰高斯拟合,计算了各高斯谱线对应的基态中最高和最低振动能级差。研究发现,溶液中乙醚分子与水分子以不同的方式结合可以形成7种能发射荧光的缔合分子,其对应的最佳吸收波长不同,引起高斯谱线的半峰宽度各异,中心波长位于304nm的高斯谱线对应的能级差最大。研究结果为乙醚-水溶液中分子缔合结构的进一步研究提供了参考。 相似文献
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E.S. Shklavtsova S.A. UshakovaV.N. Shikhov O.V. Anishchenko 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Plants intended to be included in the photosynthesizing compartment of the bioregenerative life support system (BLSS) need to be studied in terms of both their production parameters under optimal conditions and their tolerance to stress factors that might be caused by emergency situations. The purpose of this study was to investigate tolerance of chufa (Cyperus esculentus L.) plants to the super-optimal air temperature of 45 ± 1 °C as dependent upon PAR (photosynthetically active radiation) intensity and the duration of the exposure to the stress factor. Chufa plants were grown hydroponically, on expanded clay, under artificial light. The nutrient solution was Knop’s mineral medium. Until the plants were 30 days old, they had been grown at 690 μmol m−2 s−1 PAR and air temperature 25 °C. Thirty-day-old plants were exposed to the temperature 45 °C for 6 h, 20 h, and 44 h at PAR intensities 690 μmol m−2 s−1 and 1150 μmol m−2 s−1. The exposure to the damaging air temperature for 44 h at 690 μmol m−2 s−1 PAR caused irreversible damage to PSA, resulting in leaf mortality. In chufa plants exposed to heat shock treatment at 690 μmol m−2 s−1 PAR for 6 h and 20 h, respiration exceeded photosynthesis, and CO2 release in the light was recorded. Functional activity of photosynthetic apparatus, estimated from parameters of pulse-modulated chlorophyll fluorescence in Photosystem 2 (PS 2), decreased 40% to 50%. After the exposure to the stress factor was finished, functional activity of PSA recovered its initial values, and apparent photosynthesis (Papparent) rate after a 20-h exposure to the stress factor was 2.6 times lower than before the elevation of the temperature. During the first hours of plant exposure to the temperature 45 °C at 1150 μmol m−2 s−1 PAR, respiration rate was higher than photosynthesis rate, but after 3–4 h of the exposure, photosynthetic processes exceeded oxidative ones and CO2 absorption in the light was recorded. At the end of the 6-h exposure, Papparent rate was close to that recorded prior to the exposure, and no significant changes were observed in the functional activity of PSA. At the end of the 20-h exposure, Papparent rate was close to its initial value, but certain parameters of the functional activity of PSA decreased 25% vs. their initial values. During the repair period, the parameters of external gas exchange recovered their initial values, and parameters of pulse-modulated chlorophyll fluorescence were 20–30% higher than their initial values. Thus, exposure of chufa plants to the damaging temperature of the air for 20 h did not cause any irreversible damage to the photosynthetic apparatus of plants at either 690 μmol m−2 s−1 or 1150 μmol m−2 s−1 PAR, and higher PAR intensity during the heat shock treatment enhanced heat tolerance of the plants. 相似文献
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J. Wang J.S. Deng J. Cui L. Cao Y.L. Qiu J.Y. Wei 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The potential effect of the lunar exosphere on the near-ultraviolet sky background emission is predicted for Lunar-based Ultraviolet Telescope (LUT: a funded Chinese scientific payload for the Chang’e-III mission). Using the upper limit on the OH concentration inferred from the recent MIP CHACE results, our calculations show that the sky brightness due to the illuminated exosphere is <8.7 photons−1 cm−2 arcsec−2 within the wavelength range 245–340 nm. By evaluating the signal-to-noise ratios of observations of an AB = 13 mag point source at a series of sky background levels, our analysis indicates that the detection performance of LUT can be moderately degraded by the lunar exosphere emission in most cases. An AB = 13 mag point source can still be detected by the telescope at a signal-to-noise ratio more than 8 when the OH concentration is less than 2 × 108 molecules cm−3. However, the effect on the performance is considerable when the exosphere is as dense as suggested by CHACE. 相似文献
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Gaohong Wang Zongjie Hao Ralf H. Anken Jinying Lu Yongding Liu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The higher plant Wolffia arrhiza is regarded to be well suited concerning the provision of photosynthetic products in the cycle of matter of a Controlled Ecological Life Support System (CELSS) to be established in the context of extraterrestrial, human-based colonization and long-term space flight. Since UV radiation is one major extraterrestrial environmental stress for growth of any plant, effects of UV-B radiation on W. arrhiza were assessed in the present study. We found that UV-B radiation significantly inhibited photosynthetic CO2 assimilation activity, and the contents of chlorophyll a, chlorophyll b (Chl a, Chl b) and carotenoids considerably decreased when plants were exposed to UV-B radiation for 12 h. High UV-B radiation also declined the quantum yield of primary photochemistry (φpo), the quantum yield for electron transport (φEo) and the efficiency per trapped excitation (Ψo) in W. arrhiza simultaneously, while the amount of active PSII reaction centers per excited cross section (RC/CS) and the total number of active reaction centers per absorption (RC/ABS) had comparative changes. These results indicate that the effects of UV-B radiation on photosynthesis of W. arrhiza is due to an inhibition of the electron transport and via inactivation of reaction centers, but the inhibition may take place at more than one site in the photosynthetic apparatus. 相似文献
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血药浓度在位检测仪的光路设计 总被引:1,自引:1,他引:0
介绍了血药浓度在位检测仪的光路设计,重点阐述发如何降低光能的损耗。该仪器利用Y型光纤束把紫外光照射到血液中的药物上,再把药物发出的荧光收集并送到检测器,其信号供计算机实时采集。 相似文献
30.
以数值仿真的结果作为参考,开展了基于PLIF(平面激光诱导荧光)技术、高速摄影技术等非接触光学燃烧诊断技术的气氧/气甲烷同轴剪切喷嘴试验研究。通过联合光学诊断对不同设计工况的燃烧流场进行诊断测量,获得燃烧室内OH分布,燃烧流场发展演化过程、火焰的结构等信息,对燃烧流场进行详细的分析。研究结果表明:气氧/气甲烷剪切燃烧火焰存在明显的剪切燃烧层,且随着轴向距离的增加,火焰逐渐失稳;随燃氧速度比的增加,流场涡旋作用明显加强,火焰根部稳定段变短,瞬时火焰结构卷曲和褶皱增多;仿真计算的OH分布与试验测得的OH分布相似,仿真模型能够合理预测气氧/气甲烷同轴剪切喷嘴的燃烧流场。 相似文献