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Qian Y Engel MH Macko SA Carpenter S Deming JW 《Geochimica et cosmochimica acta》1993,57(14):3281-3293
Dipeptide hydrolysis and amino acid decomposition appear to follow a first-order rate law. The hydrolysis rate increases exponentially with increasing temperature in aqueous solution at both 265 atm and water steam pressures over the temperature range of 100 to 220 degrees C. Dipeptide hydrolysis has a lower apparent activation energy at 265 atm (44.1 KJ/mol) than at water steam pressure (98.9 KJ/mol). At lower temperatures (<200-220 degrees C), the rate of peptide bond hydrolysis is faster at 265 atm than at water steam pressure. At higher temperatures (>200-220 degrees C), however, peptide bond hydrolysis is slower at 265 atm than at water steam pressure. In aqueous solution, amino acid decomposition rates also increase exponentially with increasing temperature. Amino acid decomposition rates are much higher at 265 atm than at water steam pressure over the entire temperature range investigated. 相似文献
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H2 is the most abundant molecule in the universe. We demonstrate that this molecule may be an important component of interstellar and possibly intergalactic ices, both because it can be formed in situ, within the ices, and because gas phase H2 can freeze out onto dust grains in some astrophysical environments. The condensation-sublimation and infrared spectral properties of ices containing H2 are presented. We show that solid H2 in H20-rich ices can be detected by an infrared absorption band at 4137 cm-1 (2.417 micrometers). The surface binding energy of H2 to H2O ice was measured to the delta Hs/k = 555 +/- 35 K. Surface binding energies can be used to calculate the residence times of H2 on grain surfaces as a function of temperature. Some of the implications of these results are considered. 相似文献
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The condensation and vaporization behavior of ices containing SO2, H2S, and CO2: implications for Io
In an extension of previously reported work on ices containing CO, CO2, H2O, CH3OH, NH3, and H2, measurements of the physical and infrared spectral properties of ices containing molecules relevant to Jupiter's moon Io are presented. These include studies on ice systems containing SO2, H2S, and CO2. The condensation and sublimation behaviors of each ice system and surface binding energies of their components are discussed. The surface binding energies can be used to calculate the residence times of the molecules on a surface as a function of temperature and thus represent important parameters for any calculation that attempts to model the transport of these molecules on Io's surface. The derived values indicate that SO2 frosts on Io are likely to anneal rapidly, resulting in less fluffy, "glassy" ices and that H2S can be trapped in the SO2 ices of Io during night-time hours provided that SO2 deposition rates are on the order of 5 micrometers/hr or larger. 相似文献
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1 前言在气象学各分支学科中,要研究或用到各种大气辐射过程。本文将只限于那些与大气中各辐射通量及其扰动的影响直接有关的研究。但是,对下列那些与大气辐射某些方面有关的领域进行评述也是必要的,尽管它们通常被认为是另外一些学科,即对诸如温度、湿度、云量、水物质及痕量气体浓度的有源和无源遥感;对海洋、冰雪圈及地质方 相似文献
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用中国数字地震台网(CDSN)记录到的来自中国周边地区中深源地震的长周期多重ScS波形,使用频域分析(相位归一和叠加)及时域分析(波形反演)技术,估算了多重ScS的衰减算子和走时差。理论计算和使用合成数据进行的数字实验表明,在大陆地区,频域分析可以得到比时域分析更稳定的关于整个地幔衰减(QScS)的结果,而时域分析对于整个地幔走时(TScS)的模拟效果更好。将这两者结合起来,可以得到关于大陆传播路 相似文献
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美国威斯康星麦迪逊大学研制的人-机对话数据存取系统(McIDAS)在气象部门得到了广泛的应用,特别是在中尺度天气研究和短时预报方面的应用有明显效果。最近,该大学为了增强MCIDAS的应用能力,又提出了研制新一代四维McIDAS工作站的设想。 相似文献
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本文讨论了巴基斯坦的地震构造,潜在震源和历史与现代地震,并在此基础上使用确定性和概率性两种方法计算了各发展断层50年内最大可能的地震在卡拉奇和海得拉巴两城市将引起的地面峰值加速度以及50年内超越概率为14%的等加速度区划图。 相似文献