长江中游城市群铁路客运联系及其空间格局演变

基于铁路客运交通流数据,借助社会网络分析方法,从外部连通、内部连通两方面分析长江中游城市群铁路客运联系及其空间格局的演变。结果表明:(1)2009年~2015年间,长江中游城市群内武汉、长沙、南昌3大中心城市在对外联系和对内联系方面均呈现"武汉最强,长沙次之,南昌最弱","马太效应"日益显著;(2)武汉、长沙、南昌三市的对外联系主导方向各异,存在明显的空间错位现象;(3)2009年~2015年间长江中游城市群内31个城市的铁路交通地位发生较大变化,武汉、长沙、南昌三市的铁路枢纽地位得到巩固与提升,与其作为三大战略支点的地位逐渐匹配;(4)长江中游城市群铁路客运网络中心化程度较低,集中趋势不明显,表现为较低水平的多中心格局;(5)2009年~2015年间,长江中游城市群铁路客运联系网络空间格局由五边形转变为"品"形,省际毗邻城市之间的联系有待进一步增强;南昌市和环鄱阳湖城市群的铁路网络建设也有待完善,以增强其在"中三角"中的支撑地位。     

Linear and cyclic aliphatic carboxamides of the Murchison meteorite: hydrolyzable derivatives of amino acids and other carboxylic acids

Analyses of fractionated aqueous extracts of the Murchison meteorite by gas chromatography-mass spectrometry after silylation with N-methyl-N (tert-butyldimethylsilyl) trifluoroacetamide have revealed an extensive series of linear and cyclic aliphatic amides. These include monocarboxylic acid amides, dicarboxylic acid monoamides, hydroxy acid amides, lactams, carboxy lactams, lactims, N-acetyl amino acids, and substituted hydantoins. Numerous isomers and homologues through at least C8 were observed in all cases, except for the N-acetyl amino acids and hydantoins. Carboxy lactams, lactams, hydantoins, and N-acetyl amino acids are converted to amino acids by acid hydrolysis, thus, these compounds qualitatively account for the earlier observation of acid-labile amino acid precursors in meteoritic extracts. Laboratory studies of the spontaneous decomposition of N-carbamyl-alpha-amino acids and their dehydration products, the 5-substituted hydantoins, have led to the recognition of a series of aqueous phase reactions by which amino acids and cyanic acid/cyanate ion in the primitive parent body might have given rise to several of the observed classes of amides, as well as to monocarboxylic acids, dicarboxylic acids, and hydroxy acids. A previously undescribed reaction of 5-substituted hydantoins with cyanic acid/cyanate ion to give carboxamides of the 5-substituent groups was observed in the course of these studies. The presence of an extensive suite of amides in a CM chondrite appears to be consistent with the interstellar-parent body formation hypothesis for the organic compounds of these meteorites. The presence of carboxy lactams and lactams along with free amino acids suggests the possibility of further chemical evolution of meteorite amino acids by thermal polymerization. The cyclic amides, given their potential for hydrogen-bonded pair formation, might be considered candidate bases for a primitive sequence coding system.     

Survival of microorganisms in smectite clays: implications for Martian exobiology

Manned exploration of Mars may result in the contamination of that planet with terrestrial microbes, a situation requiring assessment of the survival potential of possible contaminating organisms. In this study, the survival of Bacillius subtilis, Azotobacter chroococcum, and the enteric bacteriophage MS2 was examined in clays representing terrestrial (Wyoming type montmorillonite) or Martian (Fe(3+)-montmorillonite) soils exposed to terrestrial and Martian environmental conditions of temperature and atmospheric pressure and composition, but not to UV flux or oxidizing conditions. Survival of bacteria was determined by standard plate counts and biochemical and physiological measurements over 112 days. Extractable lipid phosphate was used to measure microbial biomass, and the rate of 14C-acetate incorporation into microbial lipids was used to determine physiological activity. MS2 survival was assayed by plaque counts. Both bacterial types survived terrestrial or Martian conditions in Wyoming montmorillonite better than Martian conditions in Fe(3+)-montmorillonite. Decreased survival may have been caused by the lower pH of the Fe(3+)-montmorillonite compared to Wyoming montmorillonite. MS2 survived simulated Mars conditions better than the terrestrial environment, likely due to stabilization of the virus caused by the cold and dry conditions of the simulated Martian environment. The survival of MS2 in the simulated Martian environment is the first published indication that viruses may be able to survive in Martian type soils. This work may have implications for planetary protection for future Mars missions.     

Porphyrin and chlorin distributions in a Late Pliocene lacustrine sediment

The tetrapyrroles in a highly immature Late Pliocene lacustrine sediment (Willershausen, Germany) show a simple distribution of both chlorin and porphyrin components as the free bases. The major components are C32 desoxophylloerythroaetioporphyrin (DPEP), a C33 bicycloalkano porphyrin, the chlorin analogue of the latter, and desoxophylloerythrin and its chlorin counterpart. The structure of the novel bicycloalkano chlorin was determined using a combination of two-dimensional phase-sensitive COSY NMR and nOe studies. Measurements of delta 13C and other data indicate that DPEP and the bicycloalkano porphyrin were derived from the chlorophyll(s) of photosynthetic organisms utilising a common source of CO2, probably diatoms. The occurrence of DPEP and other minor alkyl porphyrins indicates that the chlorophyll defunctionalisation pathway leading to these components can occur at low temperature and was probably biologically mediated, as was the condensation leading to the fused ring components.     

矿山遥感监测在采空区稳定性分析中的应用

针对采空塌陷区形变稳定性问题,基于矿山遥感监测技术方法,解译、对比了四川省筠连煤矿区2009年、2012年和2015年3期遥感影像,获取了采空塌陷、矿山开采点和矿山占地等动态变化信息;分析了矿山开发环境状态变化与采空塌陷区变化趋势的相关因素,认为煤矿开采状态的变化能够影响采空区形变的趋势。基于遥感监测结果,采用塌陷区稳定性分析方法,推算出采空塌陷区持续形变和新增形变信息,编制了采空塌陷区形变趋势分区预测图,并针对性地提出了下一步防治对策和建议。     

从足太阳膀胱经生理功能论治多汗症的理论探讨

多汗症归属于中医学“汗证”范畴,中医学认为,汗证的发病与阴阳营卫失衡、腠理开合失调密切相关。针灸是临床上治疗汗证的常用手段之一,但针灸治疗多汗症的机制仍有混淆。本文基于调和阴阳、腠理治疗原则,立足于经典文献,从以足太阳膀胱经发挥调和营卫表里、司膀胱津液气化、燮理五脏六腑等生理功能,结合针刺影响自主神经系统的现代研究来探讨多汗症的治疗机制,为临床实践提供参考。     

碎屑岩深水扇研究

由于认识到深水储层中富存烃类,碎屑岩深水扇引起了地质学家的兴趣。近年来,碎屑岩深水扇的研究取得了相当大的新进展,回顾和总结近年来该领域取得的进步和提出的新观点,总的来说,这些新的观点包括:碎屑岩深水扇不仅在低位体系域时产生,在沉积供给充足的高位体系域时也能够出现,但有时即使低位体系域时也不能形成深水扇;碎屑岩深水扇通常为浊流成因,但也有一些为碎屑流引起,其内部向上变粗或变厚的反韵律不明显。基于这些新观点,一些新的深水扇模式被提出,这些新的碎屑岩深水扇的模式对其形成和性质的因素,如海平面变化、构造、沉积速率、深水扇类型和性质等,考虑更加全面。结合这些新的认识,提出的深水扇模式包括:富砾、富砂、泥砂混合和富泥型模式,而每种又根据物源的性质分为点物源,线物源和多物源、这些模式考虑因素更加全面、精确,更能反映深水扇的实质,它是深水烃类勘探预测砂体分布有效的工具。